Summary Sentence: Cementless solid tri-spiked titanium shells, with a polished inner surface and improved locking mechanism, demonstrated excellent fixation and survivorship at mid-term (minimum 5 years) follow-up.

Introduction: The tri-spiked Reflection cup (Smith & Nephew, Memphis) is a second-generation solid titanium shell with a polished inner surface, no screw holes and an improved locking mechanism. The purpose of this prospective study was to evaluate the minimum 5-year clinical & radiographic results and survivorship of this second-generation acetabular component.

Methods: Between 1997 and 2003, 659 primary THA were performed using the Reflection tri-spiked socket. None of the shells had adjuvant fixation with screws. The mean follow-up time was 7.0 years (5 to 11 yrs). The patients were followed prospectively using validated clinical outcome scores (WOMAC, SF-12, Harris Hip scores) and yearly radiographs.

Results: Twenty-seven patients had died before the minimum 5-year follow-up period. The mean Harris Hip and WOMAC scores were 89 and 79 respectively at last follow-up. Three sockets (0.6%) had been revised: two for infection, one for component malpositioning. No cup was revised for aseptic loosening. Six liners were exchanged: three for residual instability, 3 for wear associated with aseptic loosening of the stem. Radiographic review of remaining cups in-situ identified no cases of loosening and only a small number of cups (< 3%) with any osteolysis. The KM survivorship analysis with revision for any reason, was 97.5% and 97.4% at 5 and 10 years, while survivorship of the acetabular component was 99.8% at 5 and 10 years.

Conclusions: This second-generation cementless solid tri-spiked titanium shell, with a polished inner surface and improved locking mechanism, demonstrated excellent fixation and survivorship at mid-term follow-up.

Sixty four patients undergoing total hip replacement (THR) were randomized to receive a peri-articular intra-operative multi modal drug injection or to receive no injection. All patients received patient controlled analgesia (PCA) for 24 hours after surgery.

Patients receiving the peri-articular injection showed significantly less PCA consumption 6 hours postoperatively (P< 0.002). The 24 hour PCA requirement post surgery was also less (P< 0.009).

The VAS score for pain on activity in the post anaesthetic care unit (PACU) was significantly less for injected patients (P< 0.04). The VAS satisfaction score for injected patients in the PACU and 4 hours post-operatively showed no statistical difference.

Peri-articular intra-operative injection with multimodal drugs can significantly reduce post-operative patient controlled analgesia requirements and pain on activity in patients undergoing total hip replacement with no apparent increase in risk.

Background: Short-term cure rates of two stage revision for infection after TKR are approximately 90%. Little is known about the long-term reinfection-free survival or the mechanical durability of the reimplanted prostheses. The purpose of the study is to evaluate the mid to long term results of this technique with regards to persistence of infection, clinical and radiographic results. The hypothesis is that the success rate of the technique is maintained through long term follow-up, with a low rate of recurrent infection and mechanical implant failure.

Methods: from January 1990 to august 2002, 124 two stage revision TKR for infection were performed at Our Institution with mean follow-up of 9,8 years (5 to 17,5).

The clinical results were evaluated with SF12, WOMAC, and KSCRS performed preoperatively and postoperatively at 5 and 10 years. A radiographic analysis was performed using x-rays of the last available follow-up.

Results: the WOMAC and KSCRS significantly improved at the 5 years follow-up decreasing slightly at 10 years. The SF12 postoperative variation was not significant. The radiographic results showed possible loosening of the tibial or femoral components on 17% and 12% of patients respectively. There were 17 reoperations, 10 of which for persistent infection (85% of survival at 10 years).

Discusssion and conclusion: we are encouraged by the rate of eradication of infection at 10 or more years in these difficult cases. The long term clinical and radiographic results are satisfactory. The study supports the sustained use of this technique for infected total knee arthroplasties.

There is an increasing trend towards performing a high tibial osteotomy (HTO) with a medial opening wedge technique. Amongst the potential advantages is easier conversion to a total knee replacement (TKR), although literature regarding this is scarce. We report our early clinical and radiological results, along with the technical issues encountered.

From our database, we identified thirty-one patients who had undergone thirty-two TKRs after medial opening wedge HTOs. Clinic and operative records were reviewed, and our database used for knee society scores. Those patients not seen in the last twelve months were reviewed in clinic. All pre- and postoperative radiographs were reviewed. The average age of the patients was fifty-seven years, and the average time from HTO to TKR was 4.5 years.

Difficulties with patella eversion were seen in 12.5%, and the knee balanced easily in 85% of cases. The tibia had minimal deformity in most cases, and all osteotomies were healed at the time of conversion. A stem was used in ten cases, and only if metalwork was removed at the time of conversion (which was done in twenty-three of the thirty-two). Minimum one year follow-up was available for twenty-six patients, with a mean follow-up time of twenty-eight months (range twelve to ninety-three months). The average Knee Society knee score was eighty-eight, function score seventy-five, and total score one hundred and sixty-two. Compared to non-matched group of 1149 primary TKRs (of older average age), the knee score was significantly lower, and there was a higher percentage of patients in the poor category. Poor results correlated strongly to the presence of chronic pain or workers compensation issues, and also to whether the knee had undergone revision HTO prior to TKR.

We conclude that the conversion of a medial opening wedge HTO to a TKR is relatively straightforward technically, and some aspects are easier than performing a TKR after a lateral closing wedge osteotomy (using historical controls). The clinical results appear inferior to that of a TKR performed without a prior osteotomy, although the results in our osteotomy group were skewed by a small group of chronic pain and workers compensation cases.

The purpose of this study was to analyse the twenty to twenty-five year outcomes of one hundred and ninetyfive cemented, matte finish, HD-2 THRs performed in one hundred and sixty-six patients with osteoarthritis of the hip by two surgeons.

The one hundred and ninety-five THRs (one hundred and sixty-six patients) were followed prospectively by clinical assessment using the Harris Hip Score (HHS) and radiographic analysis.

One hundred and forty-nine patients (90%) died with their implant still functioning or still had a successful implant at twenty to twenty-five years follow-up. Ten patients (6%) underwent a revision for aseptic loosening of the acetabular (n=2, 1.2%) or femoral (n=4, 2.4%) component, or both (n=4, 2.4%), that was related to wear-induced osteolysis. 7 (4.2%) patients (eight hips) were lost to follow-up. The mean HHS at the latest follow-up (twenty to twenty-five years) was 88±9. Radiographically, twenty-nine (85%) of the acetabular components were well fixed and four (12%) were probably or possibly loose. Two hips (6%) had probable or possible loosening of the femoral component. At twenty five years, the calculated cumulative survival rate (Kaplan-Meier method) revealed excellent results for revisions (83%±6, any cause) and aseptic loosening (86%±6, femoral component, 93%±3, acetabular component).

The surviving patients had a good mean follow-up and radiographic fixation, proving the exceptional long-term success of this implant.

The purpose of this study is to compare the long-term clinical results of two total knee replacement designs (the SAL-II mobile-bearing implant and the fixed-bearing Genesis I implant) to see if there are any advantages to the use of a mobile-bearing design in the long-term.

One hundred and ninety-two patients with an age range between twenty-five to ninety who were implanted with either an SAL-II (Group A) or GEN I (Group B) at London Health Sciences Center, University of Western Ontario, were included in the study. Patients with a diagnosis of inflammatory arthritis or with previous high tibial osteotomy were excluded from the study. Demographic data as well as functional outcome measures such as range of motion, knee alignment, specific measures of activities with daily tasks, and composite knee scores such as the Knee Society Clinical Score and Functional Score were collected from the patients’ medical charts and compared. Data was analyzed using SPSS V14.0 statistical software.

Group A included eighty-three mobile-bearing platform arthroplasties in seventy-seven patients. There were forty-one males and thirty-six females. The average age of the patients at the time of surgery was 67.7. Average follow up time was 10.56 years from the date of surgery. Eleven patients were excluded from the study, ten due to previous HTO surgery and one due to rheumatoid arthritis. At latest follow-up, ten patients required revision, and fifteen patients died. Group B included one hundred and thirty-one fixed-bearing knee arthroplasties in one hundred and fourteen patients. There were forty-one males and seventy-three females. The average age of the patients at the time of surgery was 65.8. Average follow up time was 9.58 years from the date of surgery. Twenty five patients were excluded from the study, twenty three patients due to previous HTO surgery and two patients due to rheumatoid arthritis. At latest follow-up, thirteen patients required revision, and twelve patients had died. Include Results and p-values at this stage. No statistically significant difference was found between the groups, either for the knee score (p=0.536), the function score (p=0.115), the range of movement (p=0.718) and number of revisions. Ten years survivorship for mobile bearing group was significantly lower than the fixed bearing group (p=0.005) although this equalised at fifteen years.

This study is the first long-term study that compares the results of the mobile-bearing and fixed bearing designs performed by the same surgeons in the same period of time. The results of this study show no difference in these two designs at a mean of ten years follow-up although fixed bearing design demonstrated better overall ten years survivorship. This difference can be related to the earlier mobile bearing revisions due to aseptic loosening and instability. Mobile bearing designs have yet to prove their theoretical advantage in clinical practice.

This study reports the survivorship free of revision or radiographic loosening of one hundred and eight consecutive cemented Miller-Galante unicompartmental knee arthroplasties at a mean ten-year follow-up.

The purpose of this study was to report our experience with the Miller-Galante (MG) unicompartmental knee arthroplasty (UKA) at a mean ten-year follow-up in order to determine if this procedure can provide durable long-term clinical results.

One hundred and eight cemented MG-UKAs in eighty-two patients performed by two surgeons between 1988 and 1997 were reviewed. There were one hundred and six medial and two lateral MG-UKAs performed. Mean age at surgery was sixty-seven years (range, thirty-nine to eighty-seven). There were forty-four males and thirty-eight females. Mean follow-up was ten years (range, five to thirteen). A Kaplan-Meier survivorship analysis using an end-point of revision surgery or radiographic loosening was employed to determine probability of survival at five and ten years.

Of the eighty-two patients (one hundred and eight knees), nine patients (eleven knees) died and one patient (two knees) was lost to follow-up. Eleven patients (eleven knees) were revised at a mean of four years (range, one to nine), and one patient demonstrated radiographic loosening of the tibial component at seven years. Of the eleven revisions, only two required use of revision components. Mean pre-operative and final follow-up Knee Society clinical and functional scores were forty-seven and fifty-three, and ninety and seventy-nine points, respectively. Kaplan-Meier survivorship analysis revealed a probability of survival free of revision or radiographic loosening of 93% at five years and 88% at ten years.

The results of this study demonstrate that the MG-UKA can provide reliable pain relief and restoration of function in selected patients. Our experience has shown that the survivorship of the MG-UKA approaches that of tricompartmental knee arthroplasty, and suggests that UKA may offer the advantage of ease of revision.

Isolated liner exchange in revision total hip arthroplasty for the treatment of polyethylene wear is an increasingly common surgical procedure. Twenty-four hips underwent this procedure via the direct lateral approach and were prospectively followed clinically and radiographically. Accessible osteolytic lesions were curetted and bone grafted. At a mean follow-up of forty months, a significant clinical improvement was observed. One cup collapsed into an osteolytic lesion postoperatively; all other lesions regressed. No dislocations have occurred. Isolated liner exchange via the direct lateral approach may reduce dislocation rates while avoiding the morbidity associated with the removal of well-fixed components.

The purpose of this study was to evaluate the clinical and radiographic results of isolated liner exchange in revision total hip arthroplasty (THA) for osteolysis and polyethylene wear via the direct lateral surgical approach.

Retention of well-fixed implants avoids unnecessary bone loss at revision surgery. Previous studies report a significant dislocation rate with isolated liner exchange. Revision via the direct lateral surgical approach may reduce the dislocation rate in surgery for acetabular osteolysis.

Twenty-four hips that underwent an isolated liner exchange revision procedure via the direct lateral approach were prospectively followed. Accessible osteolytic lesions were curetted and bone grafted. Harris Hip Score, WOMAC Index, and radiographic analysis were recorded. The area of osteolytic lesions was calculated using a computer imaging technique.

At mean follow-up of forty months, all except one of the osteolytic lesions had regressed in size. Mean Harris Hip scores improved from sixty-nine to eighty-three and WOMAC indices improved from thirty-seven to twenty-four. No dislocations have occurred. One cup collapsed into an osteolytic lesion postoperatively, requiring an acetabular revision procedure.

Isolated liner exchange is a promising technique that avoids the removal of well-fixed acetabular implants. The increased dislocation rate associated with revision THA may be reduced and osteolytic lesions may be debrided and bone grafted through the direct lateral approach.

Isolated liner exchange via the direct lateral approach reduces the dislocation rate in THA. Retention of wellfixed implants and bone grafting is a procedure that preserves bone stock and addresses osteolytic lesions at revision surgery.

The results of a randomized controlled clinical trial of ninety patients comparing resurfacing to non-resurfacing of the patella in total knee arthroplasty (TKA) are reported with a minimum of ten-years of follow-up. Using a cruciate retaining hybrid TKA, the outcome measures included Knee Society Clinical Rating scores, functional testing (stair climb and flexion extension torques), patient satisfaction, anterior knee pain, and a patellofemoral specific questionnaire. The results indicated no difference between the groups in all categories. Results at two and ten years postoperatively are compared. This study represents the longest follow-up to date comparing resurfacing to nonresurfacing of the patella.

Patellar resurfacing in TKA remains controversial.

Purpose: To evaluate the results of resurfacing/non-resurfacing of the patella in a randomized controlled clinical trial at a minimum of ten-years of follow-up.

One hundred knees (ninety patients) with osteoarthritis were enrolled in a prospective randomized controlled double-blinded trial using the same posterior cruciate retaining total knee replacement. Patients were randomized to resurfacing or nonresurfacing of the patella. Evaluations were performed preoperatively and yearly to a minimum ten years (range, 10.1–11.5 years) postoperatively. Disease specific (Knee Society Clinical Rating System), functional (stair climbing, knee flex-ion/extension torques, patellar examination) outcomes were measured. Patient satisfaction, anterior knee pain, and patellofemoral questionnaires were completed. Intraoperative grading of the articular cartilage was performed.

No patients were lost to follow-up; forty-six knees remained alive. Nine revisions (9/90-ten percent) were performed – 7/48 (fifteen percent) in the nonresurfaced and 2/42 (five percent) in the resurfaced group. Three knees in the nonresurfaced group were revised to a resurfaced patella for anterior knee pain. One resurfaced patella was complicated by AVN and fracture, requiring revision. No significant difference was found between the groups regarding revision rates, KSCR score, functional, satisfaction, anterior knee pain, patellofemoral, and radiographic outcomes. Intraoperative cartilage quality was not a predictor of outcome.

This study represents the longest follow up to date of a randomized controlled clinical trial to examine patellar resurfacing in TKA. The results showed no significant difference between the groups for all outcome measures at a minimum of ten-years.

The pathogenesis of osteolysis in failed total hip arthroplasty is not fully understood. The purpose of this study is to identify CD4+CD25+ Regulatory T cells in periprosthetic tissues in failed total hip replacements secondary to osteolysis. Intra-operative tissue samples and peripheral blood were collected from patients undergoing revision total hip arthroplasty surgery. Regulatory T cells were present in the tissues, and significantly increased in the peripheral blood in patients with failed total hips compared to normal controls. Further characterization of these regulatory T cells are warranted as they may play a role in osteolysis in loose total hip replacements.

Osteolysis remains the most common complication following total joint arthroplasty. To date, no authors have investigated the role of CD4+CD25+ regulatory T cells (T_REG) participating in the osteolytic pathogenesis. The purpose of this study is to quantitate the presence of T_REG cells in periprosthetic tissues in failed total hip replacements secondary to osteolysis.

Fifteen consecutive patients booked for revision total hip arthroplasty secondary to osteolysis were included. Tissue samples were collected: peripheral blood (PB), synovial fluid (SF), synovial tissue (ST), and interface tissue (IT) between the failed component and the bone defect. Total lymphocytes were isolated and analyzed using fluorescent-tagged antibody cell sorting (FACS) for the presence of T_REG cells. Frozen sections of ST and IT were analyzed with immunohistochemistry for T_REG cells.

T_REG cells were significantly upregulated (p< 0.01) in the PB (68%) of revision hip patients compared to normal controls PB (44%). In the synovial tissue (ST) and interface tissue (IT), 57% of the lymphocytes isolated were TREG cells. The presence of T_REG cells in the ST and IT were confirmed with immunohistochemistry.

T_REG cells are upregulated in the peripheral blood of patients with failed total hips secondary to osteolysis. The TREG cells are also present in the synovial tissue and interface tissue.

Evidence for involvement of regulatory T cells contribute to our understanding of this complex biologic response to artificial wear particles.

Functional studies of these T_REG cells are warranted as they are upregulated in patients with loose total hip replacements.

Fixed bearing and mobile bearing knee designs are both currently used in clinical practice with little evidence- based research available to determine superiority of one system. We performed a prospective, randomized, blinded clinical trial to compare a mobile bearing to two standard fixed bearing implants. A single observer was used to measure all range of motion scores. We evaluated the short and long- term outcomes of the SAL^® (mobile bearing) versus the AMK^® and Genesis II^® (fixed bearings) total knee joint replacements. Minimum two- year follow-up revealed no differences in the outcome measures (WOMAC, SF-12, Knee Society Clinical Rating System).

The purpose of this study was to compare the results between a cruciate retaining mobile bearing total knee (SAL^®, Sulzer) and two cruciate retaining fixed bearing total knee prostheses (AMK^®, Depuy and Genesis II^®, Smith and Nephew).

Ninety patients were randomized to receive a SAL, AMK, or GenesisII prostheses. Patients were evaluated pre-operatively, at three, twelve months and annually thereafter. Patient demographics, radiographs, and multiple outcome measures (WOMAC, SF-12 and the Knee Society Clinical Rating System) were evaluated.

No patients were lost to follow-up. One patient was withdrawn due to dementia before three months, one patient died prior to the two year follow up, and one patient was revised for infection at 6 months leaving eighty-seven patients at an average follow-up of 3.37 years (range 2.91 – 4.44 years). There were no significant differences in any outcome measures or radiographic findings. There were no differences in KSCRS at two years (SAL - 167, AMK – 158, GenesisII – 166). There were no differences in knee flexion at two years (SAL – 117^°, AMK – 115^°, GenesisII – 118^°).

No differences in multiple outcome measures were seen between a cruciate retaining mobile bearing and two cruciate retaining fixed bearing total knee prostheses.

In this prospective randomized clinical trial no differences could be seen between a mobile bearing and two fixed bearing designs at a minimum of two years follow-up. Long-term evaluation will be required to comment on differences in polyethylene wear and implant longevity.

Funding: London Health Sciences Centre Internal Research Fund

Fixed bearing and mobile bearing knee designs are both currently used in clinical practice with little evidence- based research available to determine superiority of one system. We performed a prospective, randomized, blinded clinical trial to compare a mobile bearing to two standard fixed bearing implants. A single observer was used to measure all range of motion scores. We evaluated the short and long- term outcomes of the SAL^® (mobile bearing) versus the AMK^® and Genesis II^® (fixed bearings) total knee joint replacements. Minimum two- year follow-up revealed no differences in the outcome measures (WOMAC, SF-12, Knee Society Clinical Rating System).

The purpose of this study was to compare the results between a cruciate retaining mobile bearing total knee (SAL^®, Sulzer) and two cruciate retaining fixed bearing total knee prostheses (AMK^®, Depuy and Genesis II^®, Smith and Nephew).

Ninety patients were randomized to receive a SAL, AMK, or GenesisII prostheses. Patients were evaluated pre-operatively, at three, twelve months and annually thereafter. Patient demographics, radiographs, and multiple outcome measures (WOMAC, SF-12 and the Knee Society Clinical Rating System) were evaluated.

No patients were lost to follow-up. One patient was withdrawn due to dementia before three months, one patient died prior to the two year follow up, and one patient was revised for infection at 6 months leaving eighty-seven patients at an average follow-up of 3.37 years (range 2.91 – 4.44 years). There were no significant differences in any outcome measures or radiographic findings. There were no differences in KSCRS at two years (SAL - 167, AMK – 158, GenesisII – 166). There were no differences in knee flexion at two years (SAL – 117^°, AMK – 115^°, GenesisII – 118^°).

No differences in multiple outcome measures were seen between a cruciate retaining mobile bearing and two cruciate retaining fixed bearing total knee prostheses.

In this prospective randomized clinical trial no differences could be seen between a mobile bearing and two fixed bearing designs at a minimum of two years follow-up. Long-term evaluation will be required to comment on differences in polyethylene wear and implant longevity.

Funding: London Health Sciences Centre Internal Research Fund

The Self Aligning (SAL I) total knee prosthesis (Sulzer, Winterthur) is a first generation cruciate retaining mobile bearing implant allowing unrestricted rotation and up to 5 mm. of translation. A consecutive series of two hundred and three SAL I components in one hundred and sixty- seven patients were implanted between 1990 and 1994 and were reviewed clinically and radiographically. Quality of life outcomes (SF-12 and WOMAC) were also reviewed pre-operatively and regular intervals. This first generation mobile bearing knee implant in this series, continues to function well at a minimum ten years follow-up, with a mechanical failure rate (8%) comparable to fixed bearing designs.

A consecutive series of SAL I total knee arthroplasties were performed between 1990 and 1994 and were reviewed clinically, radiographically and with standardized quality of life outcome tools, including the SF-12 and the Western Ontario MacMaster Osteoarthritis Index (WOMAC).

Patient demographics, radiographs, and multiple validated outcome measures (WOMAC, SF12, Knee Society Clinical Rating System) were evaluated pre-operatively, at three, twelve, and twenty-four months and every two years thereafter.

The series included two hundred and three SAL I implants in one hundred and sixy-sevenpatients. There have been sixty-nine patient deaths (eighty-five procedures), nine patients (eleven procedures) now reside in nursing homes and are unable to return due to medical complications, two patients (three procedures) could not be located. Nine-teen patients/procedures have had revision surgery. Therefore, seventy-six patients (ninety-three procedures) were evaluated with over ten year follow-up (average 10.89 years, range 10.03–13.72). Indications for revision included, sepsis (three), aseptic loosening (eight), instability (two) and poly-wear (six). The KSCRS was assessed for all remaining patients at greater than ten years including pain (45.83), function(65.60), range of motion extension(0.13) and flexion(113.82) as well as the results of the WOMAC (pain-4.36, joint stiffness-2.29, function-18.66, total- 15.92) and SF-12 (Mental-55.37 Physical- 34.99).

The SAL I mobile bearing implant continues to perform comparably to fixed bearing cruciate retaining designs.

This first generation mobile bearing knee implant continues to function well at a minimum ten years follow-up, with a mechanical failure rate (8%) comparable to fixed bearing designs.

The purpose of this study was to determine contact patterns in cementless acetabular cups using a novel computed tomography (CT) scan analysis technique. Eighteen embalmed cadaveric hemipelvis specimens were randomly assigned to receive one of three cup designs. A custom CT platform was designed to optimize imaging of the acetabular cups. After cup implantation, specimens were mounted on the platform and imaged in a spiral CT scanner. Contact analysis was preformed using custom-developed imaging software. The hemisphere, dual geometry and spiked cup designs analyzed using this CT analysis technique demonstrate differences in the amount and distribution of bone pros-thesis contact.

The purpose of this study was to determine contact patterns in cementless acetabular cups using computed tomography (CT) scan analysis.

Eighteen embalmed cadaveric hemipelvis specimens were randomly assigned to receive a hemispherical cup, a dual geometry cup, or a spiked cup. After radiographic templating, an experienced orthopaedic team prepared the specimens and implanted the acetabular cups. A custom CT platform was designed to optimize imaging of the acetabular cups. After cup implantation, specimens were mounted on the platform and imaged in a spiral CT scanner. Contact analysis was preformed using custom-developed imaging software. Contact was defined as a bone-prosthesis distance of 0.5 mm or less.

The mean amount of cup contact was 40.4% (SD=8.2%) in the hemisphere group, 24.7% (SD=2.3%) in the dual geometry group, and 29.7% (SD=9.5%) in the spiked group. Colour mapping of the bone-prosthesis gap was used to identify contact/non-contact regions along the acetabular contour for all cup designs.

Preliminary work with this CT analysis technique demonstrates differences in the amount and distribution of contact in the acetabular cup designs. Future work will involve development of an imaging phantom to clarify error, use of the technique with different cup designs and reaming techniques, and comparison of this technique with conventional CT scan techniques.

This study outlines a novel CT analysis technique for quantitatively determining bone-prosthesis contact for cementless acetabular cups.

The hemisphere, dual geometry and spiked cup designs analyzed using this CT analysis technique demonstrate differences in the amount and distribution of bone prosthesis contact.

Funding: Smith and Nephew

In recent years articulating cement spacers have been used to treat infected knee arthroplasty. The aim has been to better maintain tissue planes and joint mobility thereby improving second stage re-implantation surgery. Two groups of patients treated for infected knee arthroplasty were reviewed. Twenty-six patients with articulating and forty patients with static antibiotic-impregnated methyl-methacrylate spacers were compared. The articulating spacers demonstrated easier surgical exposure at second stage and improved range of knee motion after re-implantation. There was no compromise in the rate of infection eradication with articulating spacers. Bone loss at revision was independent of spacer type.

To compare the results of patients treated with articulating versus static antibiotic-impregnated spacers for infected knee arthroplasty.

Articulating cement spacers facilitate re-implantation surgery by maintaining tissue planes and joint mobility without compromising joint stability or eradication rate of infection. Patients demonstrate better range of motion and less complications related to the extensor mechanism with the articulated spacer.

Antibiotic impregnated methyl-methacrylate spacers have become a mainstay in two-stage revision arthroplasty for sepsis. It is thought that articulating cement spacers facilitate prosthesis re-insertion by better maintaining tissue planes and joint mobility between stages.

In the articulating group fewer extensile exposure methods were required at second stage prosthesis reimplantation (19% vs 36 %). No tibial tuberosity osteotomies have been required since using the articulating spacer. The articulating group demonstrated a significantly improved range of flexion compared to the static group(106 vs 97 degrees- p=0.045) and had fewer patients with significant loss of extension or quadriceps lag. Eradication of infection was improved in the articulating group (92% vs 82%) but at shorter average follow-up. The need for augments and stabilized prostheses at revision surgery as a measure of bone loss was no different between the groups but was related to the number of prior surgical procedures.

Twenty-six patients treated with articulating spacers were compared to a matched consecutive group of forty patients treated with static spacers. Minimum follow-up was twelve months from second stage re-implantation (average twenty-two months articulating, forty months static)

Funding: No direct funding from any commercial source has been received for this study. The primary author’s fellowship position is partially funded by Smith and Nephew Richards Inc.

The results of a randomized controlled clinical trial of ninety patients comparing resurfacing to non-resurfacing of the patella in total knee arthroplasty (TKA) are reported with a minimum of ten-years of follow-up. Using a cruciate retaining hybrid TKA, the outcome measures included Knee Society Clinical Rating scores, functional testing (stair climb and flexion extension torques), patient satisfaction, anterior knee pain, and a patellofemoral specific questionnaire. The results indicated no difference between the groups in all categories. Results at two and ten years postoperatively are compared. This study represents the longest follow-up to date comparing resurfacing to nonresurfacing of the patella.

Patellar resurfacing in TKA remains controversial. Purpose: To evaluate the results of resurfacing/non-resurfacing of the patella in a randomized controlled clinical trial at a minimum of ten-years of follow-up.

One hundred knees (ninety patients) with osteoarthritis were enrolled in a prospective randomized controlled double-blinded trial using the same posterior cruciate retaining total knee replacement. Patients were randomized to resurfacing or nonresurfacing of the patella. Evaluations were performed preoperatively and yearly to a minimum ten years (range, 10.1–11.5 years) postoperatively. Disease specific (Knee Society Clinical Rating System), functional (stair climbing, knee flexion/extension torques, patellar examination) outcomes were measured. Patient satisfaction, anterior knee pain, and patellofemoral questionnaires were completed. Intraoperative grading of the articular cartilage was performed.

No patients were lost to follow-up; forty-six knees remained alive. Nine revisions (9/90-ten percent) were performed – 7/48 (fifteen percent) in the nonresurfaced and 2/42 (five percent) in the resurfaced group. Three knees in the nonresurfaced group were revised to a resurfaced patella for anterior knee pain. One resurfaced patella was complicated by AVN and fracture, requiring revision. No significant difference was found between the groups regarding revision rates, KSCR score, functional, satisfaction, anterior knee pain, patellofemoral, and radiographic outcomes. Intraoperative cartilage quality was not a predictor of outcome.

This study represents the longest follow up to date of a randomized controlled clinical trial to examine patellar resurfacing in TKA. The results showed no significant difference between the groups for all outcome measures at a minimum of ten-years.

Constrained acetabular components are a useful adjunct for the potentially unstable hip arthroplasty. There have been concerns over implant failure and early acetabular component loosening secondary to the increased implant constraint. We report the results of a constrained ace-tabular component used as treatment for dislocating hips and as prophylaxis against dislocation in high risk primary and revision hip arthroplasty. At average 3.1 years follow-up only one insert of eighty-nine inserted had failed. No cups have demonstrated radiographic or clinical evidence of loosening. We conclude this implant is safe and effective for both the prevention and treatment of hip instability.

To review the effectiveness and durability of a constrained acetabular component used to treat and prevent recurrent dislocation after total hip arthroplasty

Constrained acetabular components of this type provide both an excellent treatment and preventative option in total hip arthroplasty. There is no evidence of accelerated cup loosening and the implant failure rate remains acceptable despite the increased constraint.

Constrained acetabular components have been mainly used as a salvage option for dislocating hip arthroplasty. There have been concerns over implant failure and early acetabular component loosening secondary to the increased implant constraint. Use of this implant can prevent dislocation in high risk patient groups (eg: revision surgery) without compromising implant longevity. This significantly reduces the potential morbidity associated with hip instability.

Eighty-nine patients received the tripolar constrained acetabular component. Fifteen were inserted for recurrent dislocation whilst seventy-two were inserted in patients felt to be at high risk of dislocation (forty-nine for intra-operative instability at revision surgery, twenty-five for primary THA in patients with poor compliance, neurological conditions or deficient abductor mechanism). One implant failed by component dissociation at eighteen months. All other recurrent dislocators remained stable. There was no evidence of accelerated component loosening at medium term review (range twelve – eighty three months, average thirty-seven months)

Radiographic and clinical data was prospectively collected on eighty-nine patients who had the constrained acetabular component inserted.

Funding: The primary author’s fellowship position is partially funded by Smith and Nephew Richards Inc.

Purpose: The young patient with hip arthritis remains one of the biggest challenges to arthroplasty surgeons. The difficulty of providing a long-lasting total hip arthroplasty (THA) has been clearly documented in the literature. The aim of this study was to assess the outcomes of uncemented THA’s performed in our unit in patients aged under 50.

Methods: In our unit information on all patients is recorded prospectively on an arthroplasty database. From this database we identified 273 uncemented THAs in 237 patients under the age of 50 performed in our unit between 1985 and 2000 with a minimum of 5 year follow up. Outcomes were assessed in terms of 10 and 15-year survival with revision for any reason as the endpoint. Hip scores at routine and most recent follow-up were also reviewed. All surviving implants were radiographically assessed for acetabular wear, component loosening and for the presence of osteolysis.

Results: The mean age of patients at the time of surgery was 41.1 years. 36 patients had bilateral THA. The overall 10 and 15 year survival was 88.7 ± 2.4% and 65.6 ± 4.8 % respectively. Femoral stem survival was significantly higher at 100 % and 98.4 ± 1.6% at 10 and 15 years. Acetabular component survival was 88.6 ± 2.5 % at 10 years and 65.9 ± 4.8 % at 15 years. In unrevised THA’s 56.9% had asymmetric polyethylene wear > 2mm. 2% had definite evidence of acetabular loosening. 25.5% had radiographic evidence of femoral cortical hypertrophy or spot-welds. The mean HHS pre–operatively, at 5 and 10-year follow-up was 46.4 ± 13, 90.7 ± 12.2 and 87.9 ± 14.7 respectively.

Conclusions: Uncemented THA is effective even in young active patients. The main challenges remain ace-tabular polyethylene wear and loosening. Femoral uncemented stems provide long-term functional fixation. Contemporary bearing surfaces in association with such stems may provide long lasting THA’s even in young active patients.

One hundred and thirty-one cemented femoral stems inserted during revision total hip arthroplasty were reviewed to determine component survival. Harris Hip scores and complete radiographs were analysed. Survival at 10.5 years was 86.9%. Radiographically, 76.9% of the remaining components were classified as stable or possibly loose. Chi-square analysis of demographic and surgical factors determined age < 60 years, male gender and stems > 200 mm in length contributed significantly to failure (p < 0.05). Contrary to published results, we found that longer stems were more susceptible to failure. Revision femoral THA to a cemented component is an effective procedure that exhibits good long-term survival.

The purpose of this study was to determine the long-term survival of cemented femoral components in revision total hip arthroplasty (THA) and to identify factors significant to implant failure.

Cemented femoral components demonstrate good long-term survival and remain a suitable option for revision THA for hips with an intact cortical tube.

We report high long-term survival for this increasingly popular procedure, and contradict published results regarding the relationship between stem length and failure.

A consecutive series of one hundred and thirty-one THA revisions using a cemented femoral component were reviewed. Ninety-four hips in eighty-five patients alive > six years post-operatively were studied with a mean follow-up of 10.5 years. Hips excluded from analysis were thirty deceased and seven lost to follow-up before six years post-operatively. Implant success was graded radiographically and by comparing pre-operative to recent Harris Hip scores.

Of the ninety-four hips, fifteen (16%) femoral components were subsequently revised; nine (9.6%) for aseptic loosening, three (3.2%) for periprosthetic fracture, and one (1.1%) for each of stem fracture, instability, and sepsis. Survival at 10.5 years was 86.9% for all reasons and 91.0% for aseptic loosening as an endpoint. 76.9% of the retained components were radiologically classified as stable or possibly loose at follow-up. Factors significant for failure included age at revision < sixty years (p = 0.003), male patients (p = 0.036) and stems > 200 mm in length (p = 0.024).

In recent years articulating cement spacers have been used to treat infected knee arthroplasty. The aim has been to better maintain tissue planes and joint mobility thereby improving second stage re-implantation surgery. Two groups of patients treated for infected knee arthroplasty were reviewed. Twenty-six patients with articulating and forty patients with static antibiotic-impregnated methyl-methacrylate spacers were compared. The articulating spacers demonstrated easier surgical exposure at second stage and improved range of knee motion after re-implantation. There was no compromise in the rate of infection eradication with articulating spacers. Bone loss at revision was independent of spacer type.

To compare the results of patients treated with articulating versus static antibiotic-impregnated spacers for infected knee arthroplasty.

Articulating cement spacers facilitate re-implantation surgery by maintaining tissue planes and joint mobility without compromising joint stability or eradication rate of infection. Patients demonstrate better range of motion and less complications related to the extensor mechanism with the articulated spacer.

Antibiotic impregnated methyl-methacrylate spacers have become a mainstay in two-stage revision arthroplasty for sepsis. It is thought that articulating cement spacers facilitate prosthesis re-insertion by better maintaining tissue planes and joint mobility between stages.

In the articulating group fewer extensile exposure methods were required at second stage prosthesis reimplantation (19% vs 36 %). No tibial tuberosity osteotomies have been required since using the articulating spacer. The articulating group demonstrated a significantly improved range of flexion compared to the static group(106 vs 97 degrees- p=0.045) and had fewer patients with significant loss of extension or quadriceps lag. Eradication of infection was improved in the articulating group (92% vs 82%) but at shorter average follow-up. The need for augments and stabilized prostheses at revision surgery as a measure of bone loss was no different between the groups but was related to the number of prior surgical procedures.

Twenty-six patients treated with articulating spacers were compared to a matched consecutive group of forty patients treated with static spacers. Minimum follow-up was twelve months from second stage re-implantation (average twenty-two months articulating, forty months static)

Funding: No direct funding from any commercial source has been received for this study. The primary author’s fellowship position is partially funded by Smith and Nephew Richards Inc.

This Blinded Randomized Clinical Trial outlines: how peri-articular intra-operative multimodal analgesia significantly reduces post-operative analgesia requirement. Sixty-four patients undergoing total knee replacement were randomised to receive a peri-articular intra-operative injection containing ropivacaine, ketorolac, epimorphine and epinephrine or nothing. Patients who received the injection demonstrated greater satisfaction and pain relief. Finally, patients in the injected group did not show any signs of cardio and central nervous system toxicity.

Post-operative analgesia can be associated with troublesome side effects. Good peri-operative analgesia facilitates rehabilitation, improves patient satisfaction and may reduce hospital stay. The purpose of this study was to assess a novel cocktail for peri-articular analgesia after total knee replacement.

Sixty-four patients undergoing total knee replacement were randomised to receive a peri-articular intra-operative injection containing ropivacaine, ketorolac, epimorphine and epinephrine or nothing. The anaesthetic analgesic regime was standardised. All patients received patient controlled analgesia (PCA) for twenty-four hours post surgery, followed by standard analgesia. VAS pain scores during activity and at rest and patient satisfaction scores were recorded pre and post operatively and at six week follow up. PCA consumption and overall analgesic requirement were measured.

PCA use at six, twelve and over twenty-four hours post surgery was significantly less in patients receiving the injection (p< 0.01, p=0.016, p< 0.01). Patient satisfaction in PACU and four hours post operation was greater (p=0.016, p=0.013). VAS for pain during activity in PACU and at four hours were significantly less (p=0.04, p=0.007) in the injected group. The average ROM at six weeks was no different. Overall hospital stay and the incidence of wound complications were not different between the two groups.

Peri-articular intra-operative multimodal analgesia significantly reduces post-operative analgesia requirement. Patient satisfaction and pain relief is greater in the injection group. No cardio and central nervous system toxicity was observed.

Our novel cocktail of ketorolac, epimorphine, epinephrine and ropivacaine provides superior pain relief with no adverse side effects.

Despite favourable wear characteristics of compression molded HMWPE in vitro preliminary data show no statistical difference in wear between RAM extruded HMWPE and compression moulded polyethylene. This study reviews AP and lateral radiographs for wear using the Martell technique at two, five years and maximum follow up (mean 88.2 months).

Reduced implant survivorship due to aseptic loosening has prompted research into alternative bearing materials. Simulator testing is useful but clinical studies are the gold standard to evaluate the wear characteristics of new bearing materials.

On hundred and twelve patients matched for sex, age, body mass index, primary pathology, Charnley grade, and follow up underwent uncemented total hip replacement using an identical implant. Group One (sixty-four patients) had a RAM extruded liner (GUR 4150 HP) and Group Two (forty-eight patients) had a compression molded liner (Montell H 1900). HMWPE sterilisation regimes were identical. AP and lateral radiographs were analysed for wear using the Martell technique at two, five years and maximum follow up (mean 88.2 months).

Preliminary data show a linear and volumetric wear rate in Group One of 0.067 mm/yr and 26 mm3/year respectively between two years to maximum follow up. Similarly, the wear rates for Group Two were 0.132 mm/yr and 45 mm3/year respectively. There was no statistical difference in acetabular osteolysis between Group One (16.3%) and Group Two (15%) patients at maximum follow up.

Despite favourable wear characteristics of compression molded HMWPE in vitro preliminary data show no statistical difference in wear between RAM extruded HMWPE and compression moulded polyethylene. Quality of the wear debris is more likely to be important in producing aseptic loosening than actual wear rate.

The timing of liner exchange for retroacetabular oste-olysis in THA remains uncertain. Liner exchange should be done before the shell becomes loose. The purpose of this study was to determine the radiographic quantity of osteolysis that will predict impending loosening of the cementless shell. Osteolytic lesions were quantified radiographically using three different measures. Implant stability was confirmed intraoperatively. Percent of shell circumference with surrounding osteolysis appears to be more predictive of cementless shell loosening than the area of osteolysis. When greater than fifty percent of the shell circumference has osteolysis on AP or lateral films, liner exchange is necessary.

The timing of liner exchange for retroacetabular osteolysis in cementless THA remains uncertain. Liner exchange should be done before the shell becomes loose.

To determine the radiographic quantity of osteolysis that will predict impending loosening of the cementless shell.

Osteolytic areas differ between loose and stable shells.

Between 1992 to 2002, seventy-one cementless shells of the same design were revised at our institution; forty-six were for aseptic retroacetabular osteolysis. Radiographs and a computer-assisted technique were used to quantify osteolytic areas and percent of shell circumference associated with lesions. Implant stability was confirmed intraoperatively.

Of twenty-six stable and twenty loose shells, the average area of osteolysis on AP radiographs showed no significant difference (Stable 591mm², Loose 630 mm², p greater than 0.05); whereas, lateral radiographs demonstrated a significant difference (Stable 546 mm², Loose 837 mm², p 0.05). The percentage of shell circumference with associated osteolysis on AP and lateral films demonstrated a significant difference (AP: Stable 60, Loose 75, p 0.042; LATERAL: Stable 49, Loose73, p 0.016). Diagnostic criteria of fifty percent shell circumference associated with osteolysis on AP films has sensitivity 1, specificity 0.27 while the same criteria on lateral films has sensitivity 0.84, specificity 0.54 for shell loosening.

Percent of shell circumference with surrounding oste-olysis appears to be more predictive of cementless shell loosening than the area of osteolysis. When greater than fifty percent of the shell circumference has osteolysis on AP or lateral films, liner exchange is necessary.

Purpose: To assess the clinical utility of a computer-based program (discrete dynamic contour method of boundary refinement; Matlab®) to quantify the location and extent of periprosthetic osteolysis around cemented total knee arthroplasties.

Methods: The radiographs of 171 primary Anatomical Modular Knee arthroplasties were reviewed by three independent, blinded raters using Matlab® software program. The location, size (mm2), polyethylene sterilization technique, alignment, presence or absence of femoral osteolysis and patient characteristics was recorded.

Results: The mean duration of follow-up was 8.47 ± 1.10 years with minimum in vivo wear interval= 2.0 years. The overall incidence of radiographically apparent osteolysis was estimated at 30.41%. Furthermore, the average intra-class correlation coefficient for this measurement technique for three independent observers was found to be significant for medially and laterally located zones of osteolysis (I.C.C. value = .7801; 95% C.I. = .7161–.8316; (p< .05). There was a statistically significant trend towards higher rates of osteolysis occurring within the series of polyethylene inserts gamma irradiated in air. Lowest rates of osteolysis were measured in the series sterilized in gas plasma (27.09 mm2 per year vs. 16.24 mm2 per year respectively; p< .001).

Conclusions: The Discrete Dynamic Contour method of boundary refinement represents an acceptably reliable means by which one can quantify the location and extent of osteolysis based upon digitalized radiographs of total knee replacements.

Purpose: Post-operative analgesia using opioids or epidural analgesia can be associated with troublesome side effects. Effective peri-operative analgesia facilitates rehabilitation, improves patient satisfaction and may reduce hospital stay. Locally administered analgesia is effective, avoids systemic drug related side-effects and may be of benefit in minimally invasive joint replacement. This study compares the effects of a peri-articular injection cocktail in patients undergoing total knee and hip replacement surgery

Methods: 128 patients undergoing total knee (TKR) and hip (THR) replacement were randomised to receive a peri-articular intra-operative injection containing ropivacaine, ketorolac, epimorphine and epinephrine or nothing. The anaesthetic analgesic regime was standardised. All patients received patient controlled analgesia (PCA) for 24 hours post surgery, followed by standard analgesia. VAS pain scores during activity and at rest and patient satisfaction scores were recorded pre and post operatively and at 6 week follow up. PCA consumption and overall analgesic requirement were measured.

Results: Both TKR and THR patients used significantly less PCA 6 hours after surgery (p = 0.02 THR, p< 0.01 TKR). TKR patients receiving the injection used significantly less PCA use over 24 hours post surgery (p = 0.013). VAS for pain at 4 hrs post operation was significantly lower in the both groups (p = 0.003 TKR)(p = 0.017 THR). VAS for pain during activity at 24 hours was significantly less (p = 0.001) in the injected TKR group. Overall hospital stay and wound complications were not different between the groups.

Conclusions: Peri-articular analgesia significantly reduces post-operative analgesia requirement in TKR and THR patients. Greater satisfaction and pain relief was seen in TKR patients compared with THR.

Fifty-one prospectively followed Contour_ acetabular reconstruction cages, inserted through the direct lateral approach, were reviewed at three years minimum follow-up (range 3 to 6.4 yrs.). To date, four reoperations were required (two each for sepsis and instability) with no failures due to aseptic loosening. The Kaplan-Meier Survival Rate for any reoperation was 87% at 6.4 years. Short to mid-term follow-up of a single type of acetabular reconstruction cage, inserted through the lateral approach, demonstrated this to be a successful reconstruction option in the management of large acetabular bone defects.

This study reports the mid-term results of a single design of acetabular reconstruction cage inserted through the direct lateral approach.

At minimum three years follow-up (range 3 to 6.4 yrs.), there were no failures due to aseptic loosening with only four of fifty-one cases requiring reoperation (two sepsis, two instability).

This review supports the use of the reconstruction cage, inserted through the lateral approach, for large defects that cannot be managed with a hemispherical porous implant.

The use of the reconstruction cage in our center is reserved for large defects that cannot be managed with a hemispherical porous implant because of insufficient bone stock for initial implant stability and/or host bone contact for in-growth. Fifty-one consecutive prospectively followed Contour_ (Smith and Nephew) acetabular reconstruction cages, inserted through the direct lateral approach, were reviewed at three years minimum follow-up (range 3 to 6.4 yrs.). The majority of cases were AAOS Type Three and Four defects in which morsellized allograft was used in forty-nine cases and structural graft in three cases. Harris hip scores improved from 32.1±17.8 pre-op to 65.3±24.1 at most recent follow-up. Defining any acetabular reoperation as a failure, four of the fifty-one cages were considered to have failed giving a Kaplan-Meier Cumulative Survival Rate of 87% at 6.41 years. Two reoperations were for recurrent dislocation and the other two for sepsis. None of the fifty-one cages have been revised for aseptic loosening to date.

Introduction: Post-operative analgesia using parenteral opioids or epidural analgesia can be associated with troublesome side effects. Good peri-operative analgesia facilitates rehabilitation, improves patient satisfaction and may reduce hospital stay. Locally administered pre-emptive analgesia is effective, reduces central hyper-sensitisation and avoids systemic drug related side-effects and may be of benefit in minimally invasive joint replacement.

Materials and methods: 64 patients undergoing total knee replacement were randomised to receive a peri-articular intra-operative injection containing ropiva-caine, ketorolac, epimorphine and epinephrine. The anaesthetic analgesic regime was standardised. All patients received patient controlled analgesia (PCA) for 24 hours post surgery, followed by standard analgesia. VAS pain scores during activity and at rest and patient satisfaction scores were recorded pre and post operatively and at 6 week follow up. PCA consumption and overall analgesic requirement were measured.

Results: PCA use over 24 hours post surgery was significantly less in patients receiving the injection (P=0.013). Patient satisfaction at 4 hrs post operation was greater (P=0.003). VAS for pain during activity at 4 hrs and 24 hours were significantly less (P=0.001) in the injected group. The average ROM at 6 weeks was no different. Overall hospital stay and the incidence of wound complications was not different between the 2 groups.

Discussion: Peri-articular intra-operative multimodal analgesia significantly reduces post-operative analgesia requirement. Patient satisfaction is greater in the injection group. No cardio and central nervous system toxicity was observed.

Introduction and Aims: To compare the results of patients treated with articulating versus static antibiotic-impregnated spacers for infected knee arthroplasty.

Method: All patients undergoing two-stage revision knee arthroplasty for sepsis in the last five years were reviewed. Twenty-six patients had been treated with articulating spacers. This group was compared to 36 patients treated with static spacers. The articulating spacer technique had been adopted more recently than the static technique. Minimum follow-up was 12 months from second stage re-implantation (average 22 months articulating, 40 months static). Patients were compared in terms of the need for extensile exposures required for re-implantation, range of motion at most recent review, eradication of infection and augmentation required on revision implants.

Results: In the articulating group, fewer extensile exposure methods were required at second-stage prosthesis re-implantation (19% vs 36%). No tibial tuberosity osteotomies have been required since using the articulating spacer. The articulating group demonstrated a significantly improved range of flexion compared to the static group (106 vs 97 degrees – p=0.045) and had fewer patients with significant loss of extension or quadriceps lag. Eradication of infection was improved in the articulating group (92% vs 82%) but at shorter average follow-up. The need for augments and stabilised prostheses at revision surgery as a measure of bone loss was no different between the groups but was related to the number of prior surgical procedures.

Conclusion: Articulating cement spacers facilitate reimplantation surgery by maintaining tissue planes and joint mobility without compromising joint stability or eradication rate of infection. Patients demonstrate better range of motion and less complications related to the extensor mechanism with the articulated spacer.

Introduction and Aims: Cemented femoral revision total hip arthroplasty has been associated with early mechanical failure by aseptic loosening. This study was performed to determine the long-term survival of cemented femoral revision arthroplasty and to identify factors predictive of failure.

Method: One hundred and twenty-nine cemented femoral revision cases were reviewed to determine component survival. Ninety-seven hips with a minimum follow-up of five years were included for survival analysis and tests of significance. Harris hip scores were used to quantify clinical outcomes. Complete radiographic series were reviewed. Kaplan-Meier survival curves were calculated. Clinical and surgical factors were analysed to determine if they were predictive of failure.

Results: Individual Harris hip scores improved to a mean of 71 at the most recent follow-up from a mean pre-operative score of 52 (p< 0.001). Kaplan-Meier survival at 10 years was 91%, with revision for aseptic loosening of the femoral component as the endpoint and 71% with mechanical failure as the endpoint. Patients older than 60 years experienced greater long-term component survival and less pain than patients younger than sixty years (p< 0.05). Good quality post-operative cement mantles were associated with better long-term radiographic fixation (p< 0.001). Poor femoral bone quality was significantly associated with an increased rate of re-revision for aseptic loosening (p=0.021).

Conclusion: Revision femoral THA with cement remains an option in selected patients with acceptable 10-year survival and fair radiographic fixation. Patients demonstrated acceptable clinical outcomes at 10 years and few experienced significant pain. The best results may be achieved in older patients with adequate bone stock and modern cementing techniques.

Introduction and Aims: The use of porous coated femoral stems in revision hip arthroplasty has been associated with a high rate of complications including femoral fracture, femoral perforation and eccentric reaming. The purpose is to determine if using a distally slotted-fluted femoral stem is associated with lower incidence of the above three intra-operative complications.

Method: The intra-operative complications of 175 cementless revision total hip arthropasties (THA) using a distally slotted-fluted femoral stem were reviewed. Three categories of complications were recorded: femoral fracture, femoral perforation and eccentric reaming. Radiographic evaluation was based on standard antero-posterior and lateral views of the hip joint performed in the intra-operative or immediate post-operative period. Statistical analysis for factors associated with complications was performed using the chi-square test.

Results: Intra-operative complications occurred in 16 patients (9.1%). There was no statistically significant association between complication rate and type of surgical approach, stem length, stem diameter, or host bone quality. The complication rate was significantly lower than the 44% total complication rate previously reported utilising a long, solid, extensively coated revision stem without a slot or flute (p< .01). These results are consistent with laboratory testing, which revealed significantly lower bone strains at the isthmus when inserting a long cementless revision stem with a slot and flute compared to a solid fully coated stem of identical geometry.

Conclusion: The use of a distally slotted fluted porous coated femoral stem in revision hip arthroplasty results in a dramatically lower complication rate compared to rates previously reported for solid porous stems. These results strongly support the continued use of such a prosthesis for revision THA.

Introduction and Aims: Problem: The timing of liner exchange for retroacetabular osteolysis in THA remains uncertain. Liner exchange should be done before the shell becomes loose.

Purpose: To determine the radiographic quantity of osteolysis that will predict impending loosening of the cementless shell.

Hypothesis: Osteolytic areas differ between loose and stable shells.

Method: Between 1992 and 2002, 71 cementless shells of the same design were revised at our institution; 46 were for aseptic retroacetabular osteolysis. Radiographs and a computer-assisted technique were used to quantify osteolytic areas and percent of shell circumference associated with lesions. Implant stability was confirmed intra-operatively.

Results: Of 26 stable and 20 loose shells, the average area of osteolysis on AP radiographs showed no significant difference (Stable 591mm2, Loose 630 mm2, p greater than 0.05); whereas, lateral radiographs demonstrated a significant difference (Stable 546 mm2, Loose 837 mm2, p 0.05). The percentage of shell circumference with associated osteolysis on AP and lateral films demonstrated a significant difference (AP: Stable 60, Loose 75, p 0.042; LATERAL: Stable 49, Loose 73, p 0.016). Diagnostic criteria of 50 percent shell circumference associated with osteolysis on AP films has sensitivity 1.0, specificity 0.27, while the same criteria on lateral films has sensitivity 0.84, specificity 0.54 for shell loosening.

Conclusion: Percent of shell circumference with surrounding osteolysis appears to be more predictive of cementless shell loosening than the area of osteolysis. When greater than 50 percent of the shell circumference has osteolysis on AP or lateral films, liner exchange is necessary.

Introduction and Aims: The dilemma to retain or sacrifice the posterior cruciate ligament in a primary total knee arthroplasty continues to be an area of discussion. A randomised clinical trial was performed comparing clinical, radiographic and quality of life outcomes between patients receiving a posterior cruciate sparing versus posterior cruciate substituting knee implants.

Method: A multi-centred, prospective, randomised, blinded, clinical trial was performed to compare posterior cruciate retaining (CR) versus posterior cruciate substitution (PS) in osteoarthritic patients with an intact posterior cruciate ligament, undergoing total knee arthroplasty using the AMK^® (Depuy^®, Warsaw, Indiana) component. One hundred and fifty-two patients were randomised to receive one of the two devices. Patients were evaluated pre-operatively, at three, six, 12 months and annually thereafter. Patient demographics, radiographs, and multiple validated, outcome measures (WOMAC, SF-12, the Knee Society Clinical Rating System, and a stair climbing test) were evaluated. Patients and assessors were blinded to the implant design.

Results: One hundred and fifty-two patients were randomised at three centres; 72 in the CR group and 80 in the PS group. One patient was revised due to instability. Average follow-up was 5.14 years (range 2.97–6.99 years). There were no significant differences in baseline patient demographics between groups. There were no significant differences in outcome measures or radiographic findings. There were no significant differences in the Knee Society Clinical Rating System (CR- 159.18 versus PS- 156.49). There were no differences in knee extension at latest follow-up (CR- 1.02) and (PS- 1.10). There were no differences in knee flexion at latest follow-up (CR-111.00 ) and (PS- 113.61). No differences were noted in the WOMAC and SF-12 scores between the two groups.

Conclusion: In this prospective randomised clinical trial no significant differences involving radiographs and multiple outcome measures could be seen between a cruciate retaining versus a posterior stabilised total knee prostheses at a mean follow-up of 5.14 years. Long-term evaluation is necessary to comment on wear, osteolysis and implant longevity.

Introduction and Aims: Problem: Patellar resurfacing in TKA remains controversial. Purpose: To evaluate the results of resurfacing/non-resurfacing of the patella in a randomised controlled clinical trial at a minimum of 10 years of follow-up.

Method: One hundred knees (90 patients) with osteoarthritis were enrolled in a prospective randomised controlled double-blinded trial using the same posterior cruciate retaining total knee replacement. Patients were randomised to resurfacing or non-resurfacing of the patella. Evaluations were performed pre-operatively and yearly to a minimum of 10 years (range 10.1–11.5 years) postoperatively. Disease-specific (Knee Society Clinical Rating System), functional (stair climbing, knee flexion/extension torques, patellar examination) outcomes were measured. Patient satisfaction, anterior knee pain, and patellofemoral questionnaires were completed. Intra-operative grading of the articular cartilage was performed.

Results: No patients were lost to follow-up; 46 knees remained alive. Nine revisions (9/90–10%) were performed – 7/48 (15%) in the non-resurfaced and 2/42 (5%) in the resurfaced group. Three knees in the non-resurfaced group were revised to a resurfaced patella for anterior knee pain. One resurfaced patella was complicated by AVN and fracture, requiring revision. No significant difference was found between the groups regarding revision rates, KSCR score, functional, satisfaction, anterior knee pain, patellofemoral, and radiographic outcomes. Intraoperative cartilage quality was not a predictor of outcome.

Conclusions: This study represents the longest follow-up to date of a randomised controlled clinical trial to examine patellar resurfacing in TKA. The results showed no significant difference between the groups for all outcome measures at a minimum of 10 years.

Introduction and Aims: Polyethylene wear in total hip arthroplasty (THA) is frequently associated with wellfixed cementless implants. Purpose: To evaluate the clinical and radiographic results of the isolated liner exchange (ILE) procedure in revision THA via the direct lateral surgical approach.

Method: A prospective study of 24 hips that underwent an ILE revision procedure via the direct lateral approach was conducted. Accessible osteolytic lesions were managed with curettage and bone grafting. Clinical data including Harris hip score, WOMAC Index, SF-12, and radiographic analysis were recorded. The area of osteolytic lesions was calculated using a new software program.

Results: This is the first study to our knowledge to report on the results of the ILE procedure performed via the direct lateral surgical exposure. Twenty-three patients underwent 24 revisions with an ILE. At mean follow-up of 40 months, all osteolytic lesions had regressed. Harris hip scores improved from 69 to 83. WOMAC indices improved from 37 to 24. No dislocations have occurred. Two patients have required revision. Isolated liner exchange for polyethylene wear is a promising technique that avoids the removal of well-fixed acetabular implants. The increased dislocation rate associated with this revision THA procedure may be reduced and osteolytic lesions may be successfully debrided and bone grafted through the direct lateral approach.

Conclusion: The ILE procedure, when performed via the direct lateral surgical approach, may reduce the dislocation rate commonly reported via the posterolateral exposure with this procedure. Retention of well-fixed implants and bone grafting preserves bone stock and adequately addresses osteolytic lesions at revision surgery through this exposure.

Introduction and Aims: Polyethylene wear continues to be the most significant issue following total hip arthroplasty (THA), leading to the current increase in use of alternative bearing surfaces. We performed a prospective, randomised, blinded clinical trial comparing metal versus polyethylene bearing surfaces in patients receiving THA.

Method: Forty-one patients were randomised to receive a metal (23) or a polyethylene (18) insert with identical femoral and acetabular components. Patients were evaluated pre-operatively at three, six, 12 months and annually thereafter, including an evaluation of erythrocyte and 24-hour urine cobalt, chromium and titanium metal ion levels, validated outcome measures (WOMAC, SF-12, Harris Hip Score) and radiographs.

Results: No patients were lost to follow-up. One patient died of unrelated causes. At an average 4.4 (range 3.3–5.1) years follow-up there were no differences in any outcome measures or radiographic findings. Patients receiving metal liners had significantly elevated metal ion measurements. At the latest follow-up erythrocyte cobalt levels were seven times elevated (median 1.2μg/l (metal) Vs 0.18μg/l (poly), p< .001). Urine cobalt levels were 41 times elevated (median 11.9μg/day (metal) Vs 0.29μg/day (poly), p< .001) and urine chromium levels were 14 times elevated (median 4.9μg/day (metal) Vs 0.36μg/day (poly), p< .001). Erthrocyte chromium, titanium and urine titanium were not significantly different between groups. As well, contrary to previous reports, there was not a significant trend towards decreasing ion levels over time.

Conclusion: In this prospective randomised blinded clinical trail comparing metal to polyethyle bearing surfaces, both cobalt and chromium ion levels were significantly elevated in the blood and urine of the patients randomised to receive the metal on metal THA.

Introduction and Aims: While highly cross-linked polyethylene has achieved widespread clinical use based on laboratory testing showing significant wear reduction, there is little clinical information demonstrating its benefits in vivo. This study reports the early clinical and wear performance of a prospective randomised controlled trial comparing highly cross-linked to standard polyethylene.

Method: One hundred patients were enrolled in a prospective randomised controlled trial in which all patients received a hybrid THR (cemented Versys stem, Triology cementless acetabulum). The two groups were virtually identical in terms of age, weight, male/female ratio and received identical hip implants, except that one half (50 patients) randomly received a highly cross-linked polyethylene liner. Clinical outcomes were determined using Harris hip, WOMAC and SF-12 scores. Two-dimensional (2D) and three-dimensional (3D) wear rates were determined using a validated radiographic technique based on AP and lateral radiographs at six weeks and one, two and three years post-operatively.

Results: At two years minimum follow-up (range two to four years), there were no differences in Harris hip, WOMAC or SF-12 scores. No patients were lost to follow-up, although five patients had died of unrelated causes. There were no infections, dislocations or revisions to date. Wear analysis at one-year post-op showed high penetration rates for both groups (mean 3D wear approximately 0.25 mm/year) consistent with the bedding-in phenomena. At most recent radiographic follow-up (two or three years), there was a statistically significant although modest difference in wear rates between the two groups with a 2D and 3D wear rate of 0.14±0.10 mm/yr and 0.15±0.02 mm/yr respectively for conventional polyethylene compared to 0.09±0.04 mm/yr and 0.11±0.02 mm/yr for cross-linked polyethylene. This represented a 32 and 29 percent reduction in 2D and 3D wear rates respectively with cross-linked polyethylene.

Conclusion: At early follow-up, there were no clinical differences. There was a modest wear reduction (approximately 30%) with highly cross-linked polyethylene, considerably less than expected based on laboratory testing. Longer follow-up, after the bedding-in process is completed, is required to demonstrate the wear reduction afforded by highly cross-linked polyethylene.

Introduction and Aims: Fixed bearing and mobile bearing knee designs are currently used in clinical practice with little evidence based research available to determine superiority of one system. The purpose of this study was to compare the results between a cruciate retaining mobile bearing and two cruciate retaining fixed bearing total knee prostheses.

Method: We performed a prospective, randomised, blinded clinical trial to compare a mobile bearing to two standard fixed-bearing implants. We evaluated the short- and long-term outcomes of the SAL^® (Sulzer) mobile bearing versus the AMK^® (Depuy) and Genesis II^® (Smith & Nephew) fixed bearing, total knee joint replacements. Ninety patients were randomised to receive one of the three prostheses. Patients were evaluated pre-operatively, at three, 12 months and annually thereafter. Patient demographics, radiographs, and multiple outcome measures (WOMAC, SF-12 and the Knee Society Clinical Rating System) were evaluated. A single observer was used to measure range of motion scores.

Results and Discussion: No patients were lost to follow-up. One patient was withdrawn due to dementia before three months, one patient died prior to the two-year follow-up, and one patient was revised for infection at six months, leaving 87 patients at an average follow-up of 3.37 years (range 2.91–4.44 years). There were no significant differences in any outcome measures or radiographic findings. There were no differences in KSCRS at two years (SAL – 167, AMK – 158, GenesisII – 166 ). There were no differences in WOMAC scores or SF-12 survey scores. There were no differences in knee flexion at two years (SAL – 117^°, AMK – 115^°, GenesisII – 118^°). Therefore, no differences in multiple outcome measures were seen between a cruciate retaining mobile bearing and two cruciate retaining fixed bearing total knee prostheses.

Conclusion: In this prospective randomised clinical trial no differences could be seen between a mobile bearing and two fixed bearing designs at a minimum of two years follow-up. Long-term evaluation will be required to comment on differences in polyethylene wear and implant longevity.

Our aim was to evaluate the functional outcome of extensile revision knee exposure techniques.

166 revision total knee arthroplasties requiring an extensile exposure with 2 year minimum follow-up were prospectively studied {81 rectus snips (RS), 42 tibial tubercle osteotomies (TTO), and 43 quadriceps turn-downs (QT)}. Patients were clinically evaluated for knee society score, range of motion (ROM) and extensor lag comparing pre-op and 24 month follow-up appointment findings. Radiological evidence of avascular necrosis (AVN) pre & post operation was recorded. The TTO group was further examined for proximal migration of the tubercle post op.

Pre-operative knee motion (75° & 71°) and knee scores (74 & 70) were lower in revision total knee arthroplasties requiring QT & TTO than those requiring a RS (91° & 84). Post op flexion and knee scores were greater in the RS group (102° & 131) than in the QT (81° & 114) and TTO (84° & 111) groups in whom there was no significant difference. Avascular necrosis of the patella was most commonly seen following QT. In both QT & TTO groups performing a lateral release was significantly associated with AVN of the patella. Extensor lag (> 10°) was seen only in the QT & TTO groups (11% & 8%) in whom there was no significant difference. Tubercle escape (> 2mm) in the TTO group was significantly greater (54%) in those where circlage wires only had been used than in those where a proximal transfixation wire was used (11%).

In conclusion, both QT & TTO groups had similarly poor knee scores & ROM pre & post operation. AVN of the patella for both groups was similar and significantly associated with performing a lateral release. Finally we would conclude that the use of a through wire significantly reduces tubercle escape in TTO fixation.

We report on five-ten year results of AORI type two bone defects treated with modular augments in revision knee surgery.

102 revision knee arthroplasties with type two defects were treated with augments & stems and minimum five-year follow-up were prospectively studied.

15 patients (16 knees) died with retention of their prosthesis, 7 knees had incomplete follow-up. There were 79 remaining knees with complete follow-up of 7+−2 years (range: 5 – 11). The presence of non-progressive radiolucent lines around the augment in 20% of knees was not associated with poorer knee scores, range of motion, component survival or type of insert used (p> 0.05). Kaplan-Meier survival of the components was 92+− 0.03% at 11 years (95%CI:10.3–11.2)

We support the use of modular augmentation devices to treat type 2 defects in revision knee surgery and conclude that theoretical concerns of fretting and loosening based on 5 – 10 year clinical data are unfounded.

Aim: unicompartmental Knee Arthroplasty (UKA) is experiencing a resurgence in popularity. In order to provide accurate indications for UKA it is essential to evaluate the long-term results and to determine which patients are appropriate candidates.

Methods: One hundred and seventeen cemented UKA were performed between 1988 and 1995 in 90 patients with osteoarthrosis. The cohort comprised 25 Brigham (BG) and 92 Miller-Galante (MG) implants performed in a sequential fashion in well-matched groups. The average age at the time of the surgery was 66.4 years (range: 39.5 years to 87.1 years). There were 72 males and 45 females. The surgery was performed by either one of two surgeons. The minimum follow-up period was five years and the maximum was 13.2 years. Data, including KSCRS scores and radiographic results, were collected prospectively for all patients.

Results: Six Patients died during the study period and two were lost to follow-up. The average time of death was eight years post-operatively, with average latest KSCRS prior to death of 184 points compared with 134.7 pre-operatively. Twelve knees were revised at an average of 4.25 years (range 1.0 – 11.8 years) after the initial surgery, with polyethylene wear and progression of arthrosis being the most common reasons. The surviving 97 implants had an average follow-up of 9.6 years, with an average KSCRS improving from 100 points pre-operatively to 172 points at latest follow-up. There was no radiographic evidence of prosthetic loosening. A survival analysis using revision as the end-point (Kaplan-Meier, 95% confidence interval) showed a 10 year survival of 89% for all prostheses, 85% for BG, and 90% for MG prostheses.

Conclusions: Relatively few reports of the long-term results of UKA are available. The results of this study are slightly inferior but still comparable to TKA after the same follow-up period, suggesting that, with proper patient selection, UKA can offer reliable relief of pain and restoration of function for patients with unicompartmental knee osteoarthrosis.

Introduction: The cement mantle is a critical factor in the longevity of cemented total hip arthroplasty (THA). Concern has been raised about the reliability of plain radiographs for its assessment. A new high-definition, three-dimensional (3-D), in vitro method of cement mantle evaluation has been developed.

Aim: To compare cement mantle quality in six contemporary stem designs.

Methods: Exact resin replicas of six contemporary stem designs were implanted into cadaver femora using third generation techniques. The specimens were imaged with a high-speed, helical, computerised, tomographic scanner. Computer-assisted, 3-D analysis of the cement mantle thickness was made. Comparisons were made between different stem designs and also with plain film assessments of the mantles.

Results: Standard radiographs overestimated mantle thickness (p< 0.05) and underestimated the deficiencies. The percentage area of cement mantle that was thinner than 2mm ranged from 9% to 28%. Slight malrotation or malalignment of the stem with respect to the broach envelope produced deficient mantles. Characteristic patterns of deficiencies were seen for different stem designs.

Conclusions: Plain x-rays overestimated the cement thickness, frequently missed areas of substandard cement, and should, therefore, be interpreted cautiously. The cement mantle varies widely depending on the stem design and surgical technique, and commonly used designs have significant deficiencies in their mantles by standard criteria despite proper surgical technique. Surgeons should be familiar with the stem that they use and its instrumentation to maximise outcomes. This is a valuable technique for the study of the cement mantle as it relates to implant design, surgical technique and patient anatomy.

Introduction: Range of motion is an invariable outcome -measure in studies on total knee arthroplasty (TKA) and other knee surgery. Concluding that a certain change in motion equals a corresponding change in outcome may be invalid if true accuracy of current measuring techniques is unknown. This is integral to many studies. Surprisingly little has been done to validate these techniques.

Methods: Maximum extension and flexion were measured in 32 TKAs by four independent observers using three common techniques: visual estimate (VE), pocket and universal goniometers (PG and UG). Lateral radiographs in reproducible positions were measured using computer analysis, providing a gold standard for comparison with clinical measurements. The correlation coefficients and coefficients of reliability were calculated.

Results: There were no significant differences between observers using any method. Significant differences were found between each technique and radiographic measure (paired t-test, p< 0.001). Correlation coefficients were lower for extension estimates (0.76–0.80) than flexion (0.91–0.96). Coefficients of repeatability varied from 11.6 degrees to 12.1 degrees for extension measurements and from 13.8 degrees to 19.2 degrees for flexion measurements, with UG being the most accurate. The VE accuracy approached that of UG only at easily visualised angles such as 90 degrees. The coefficient of repeatability for radiographic measure was significantly lower at 2.9 degrees.

Conclusions: Clinical measurements of range of motion vary significantly from radiographic measurement, with the computer assisted radiographic measurement providing high reliability as the gold standard. UG is most accurate, followed by PG and VE. However, coefficients of repeatability were surprisingly large, indicating the degree of accuracy of each measurement technique and the necessary magnitude of difference for this to be outside measurement error. This has relevance for all outcome studies and everyday clinical practice.

We randomised 250 patients undergoing unilateral, elective hip arthroplasty for osteoarthritis to receive either a cemented or a non-cemented Mallory Head prosthesis. Aspirin was used as prophylaxis against thromboembolism during the first half of the study and adjusted-dose warfarin during the second half. Postoperatively, all patients were asked to have bilateral venography and 80% agreed. All were evaluated clinically for pulmonary embolism.

There was no difference in the frequency of deep-venous thrombosis between the two groups (50% cemented v 47% non-cemented, p = 0.73; 95% CI of the difference −13.6% to 19.3%). Three of the 64 patients (5%) in whom venography had demonstrated isolated distal thrombi developed pulmonary emboli.

A retrospective review of 148 consecutive porous-coated hip arthroplasties (PCA) showed an incidence of thigh pain of 13% one year after surgery, and 22% at two years. Positive correlations were made with femoral stem subsidence (greater than 2 mm) and with distal periosteal and endosteal bone formation. No positive correlations were made with parameters of bone quality or component fit. Resolution of pain occurred in one-third and an anti-inflammatory agent produced partial relief in two-thirds of the patients. We conclude that thigh pain is secondary to stem instability with distal stress transfer in the absence of stable proximal fixation.

The results of 62 ankle arthrodeses, mostly performed for osteoarthritis, have been reviewed; of these, 39 were examined clinically and radiographically after an average follow-up period of seven years. Compression arthrodesis was associated with the highest incidence of complications, and an anterior sliding graft gave the most satisfactory results. Very few patients required modification of their footwear; most could walk independently with a slight limp and were able to return to their pre-operative work. However, after operation, the ability to run and to participate in vigorous sporting activities was limited. Complications included wound infection, non-union, and some change in midtarsal mobility, but excellent pain relief was reported by all patients.

Thirty-three Girdlestone's arthroplasties used to salvage infected total hip replacements were followed for a mean of 6.2 years to assess the efficacy of this procedure. Subjective and objective assessment was obtained at the time of review. Gram-negative organisms, retained cement, bony sequestra and secondary healing were common features of the five patients (15%) whose wounds discharged for more than four weeks after operation. Girdlestone's arthroplasty provided satisfactory pain relief in 91% of patients, and control of infection in 97%. Although leg-length discrepancy (mean 4 cm) and a Trendelenburg gait made walking difficult and tiring , 42% were satisfied with their functional ability; 85% needed walking aids, and 3 patients could not walk at all and were confined to bed or a chair. Overall, 79% were satisfied. Objectively, the mean Harris hip rating was 60; however, if patients with multiple joint problems were excluded, this score increased to 77. Girdlestone's arthroplasty seems a reasonable salvage procedure in the management of an infected total hip replacement and the results seem to improve with time.

Eighteen patients with acute compartment syndromes below the knee were treated with four-compartment fasciotomies using the double-incision technique. Pre-operative tissue pressure measurements ranged from 28 to 47 mmHg. If fasciotomy was performed within 24 hours of the onset of clinical symptoms and signs, a good result was almost always achieved. It is recommended that tibial fractures complicated with a compartment syndrome should be treated with some form of operative stabilisation of the fracture at the time of surgical fasciotomies.

The clinical results in a series of 131 patients with 134 brachial plexus injuries were analysed to determine the factors affecting prognosis. Isolated injuries to the upper trunk had the best prognosis, but the prognoses of isolated injuries to the cords, upper roots and lower trunk were not as good. Complete injuries of the plexus had the worst prognosis. Pain which persisted for more than six months was a bad prognostic sign for neurological recovery regardless of the location of the lesion. Horner's syndrome was not always accompanied by a bad prognosis. Operation did not affect the prognosis except in open lacerations. A pseudomeningocele detected by myelography usually precluded recovery in the root at the level of the pseudomeningocele.

Eighteen patients with acute dislocation of the patella had associated osteochondral fractures. This fracture complicates approximately 5% of all acute dislocations of the patella occurring in children. Three types of fracture patterns were noted. All patients who were treated by immediate arthrotomy and excision or replacement of the osteochondral fragment and repair of the acute dislocation of the patella made an uneventful recovery with no recurrence of the dislocation. In those patients in whom the osteochondral fragment was removed but with no repair the dislocation recurred.