Introduction The accuracy of UCA implantation is an important prognostic factor in survivorship. Previously, conventional instrumentation was adapted for UCA, possibly contributing to a lower long-term survivorship. This study aims to assess UCA position on x-rays, performed through a minimally invasive approach, in comparison to UCAs utilising an open approach.

Methods Patients were selected for UCA according to strict criteria. In particular, a varus knee < 15 and correct-able,< 15 fixed flexion deformity, intact cruciate ligaments and weight bearing knee x-rays indicating osteoarthritis in the antero-medial region and relative lateral compartment sparing. Patello-femoral joint disease was not an exclusion criterion. Ultimately, the decision to proceed with UCA was made at the time of surgery where the cruciates and lateral compartment could be inspected directly. Data was retrieved retrospectively for a continuous cohort of patients. Radiographs of component alignment were measured by an independent observer not involved in the surgery. Radiographs were measured for 56 UCAs, performed by one of the authors. Twelve patients had bilateral UCAs at the same surgery and one patient had a combined UCA/TKR. Short knee x-rays (anterior-posterior and lateral views) were used to estimate the axes of the femur and tibia as the reference points for component measurements.

Results The femoral component varus/valgus angle was 5.6° (range: 2 to 10) and flexion/extension angle was 4.9° (range: 0 to 11). The tibial component varus/valgus angle was 86.4° (range: 80 to 89°) and the postero-inferior tilt angle was 83° (range: 80 to 85). There was no radiolucency at the tibial plateau interface greater than one millimetre. One patient was treated for deep vain thrombosis and two patients underwent manipulations due to reduced range of motion. There were no deep or superficial infections and no UCA revisions.

Conclusions Radiological analysis of Oxford UCAs using a minimally invasive technique demonstrates similar implant positioning compared to the open approach. Patients gain the advantage of earlier recovery due to less synovial and quadriceps disturbance and no patella dislocation. Ongoing follow-up is required to determine whether these benefits extend to improved prosthesis survivorship.

Introduction THR is a successful procedure with excellent long term results. With many patients requiring the procedure there is some advantage in rapid recovery and early discharge. This may require a change in the surgical approach and peri-operative management. We report the first series of a new minimally invasive surgical approach for THR.

Methods A two incision approach for THR has been developed after extensive cadaver tests. This consists of an anterior muscle splitting incision to insert the cup and a posterior incision for the stem insertion. The authors have undergone cadaver training and clinical surgery before embarking on clinical trials. Patients included in this study are those people awaiting THR who were selected for a cementless prothesis and who would benefit from early rehabilitation. Patients with previous surgery, hip dysplasia and significant obesity were excluded. An initial study group are presented with an average age of 59, average height 168 cms and average weight 71 kg.

Results Average length of stay was 3.7 days with an average operative time of 90 minutes. Average blood loss 505 mls with an average blood usage of 1.1 units. Early complications include lateral cutaneous nerve of thigh palsy (50% resolution at three months), two stable trochanter fractures, one infection and one anterior dislocation at eight weeks with a ceramic implant.

Conclusions The approach is technically difficult and initially time consuming. It does enable quicker mobilisation and appears to result in less need for analgesia post-operatively. We believe it is important to present the early results so the technique can be discussed and potential problems avoided. A randomised, prospective trial with clinical and RSA follow-up is underway.

Introduction: Persistent acetabular dysplasia is a recognized cause of premature hip arthritis. Treatment options include joint preservation (acetabuloplasty/osteotomy) or salvage procedures (THR). Presence of a deficient acetabulum and an elevated acetabular centre make THR technically demanding with uncertain outcome. Shelf ace-tabuloplasty is a viable option, however, most reports in the literature focus on results in children and adolescents.

Aim: To investigate the functional and radiological outcome of shelf acetabuloplasty in adults with significantly symptomatic acetabular dysplasia.

Material and Methods: 77 consecutive shelf procedures (68 patients) with an average follow-up of 10.9 years (range: 6–17) were reviewed. The Oxford hip score (OHS) was used for clinical assessment. Centre-edge angle (CEA) and acetabular angle (AA) were measured as indicators of joint containment.

Results: The average age at surgery was 33 years (range: 17–60). At the time of last follow-up; the mean OHS was 34 (maximum score: 48). Mean postoperative CEA was 59 (Pre-operatively: 16.2 degrees) while mean postoperative AA was 31 (Pre-operatively: 47.5 degrees). Thirty percent of hips needed THR at an average duration of 7.3 years. Pre-operative arthritis was present in 32 hips out of which 17 (53 percent) needed THR. Out of the remaining 45 hips, only 6 (13 percent) needed THR. No correlation was found between the acetabular indices and the outcome.

Conclusion: Shelf-acetabuloplasty offers symptomatic relief to adults with acetabular dysplasia and can delay the need for THR for over 10 years. Best results with shelf-acetabuloplasty were achieved in patients without preoperative arthritis.

Correct alignment is important for success in total knee replacement. Currently this is achieved by a combination of intramedullary and extramedullary alignment using jigs and cutting blocks. This multicentre study evaluates the use of computer assisted planning and the interactive guidance of instruments for total knee replacement.

Prior to surgery computer scans of the hip, knee and ankle were performed of patients enrolled in the study. Pre operative planning of the position and size of the knee components was performed by the surgeon using a CT based Vector Vision Navigation System (Brain LAB AG, Heimstetten, Germany). P.F.C.x (De Puy Leeds UK) knee replacements were then implanted in 38 patients. Surgery was carried out according to the standard surgical technique using traditional instruments. Information of the planned and intraoperatively recorded position of the cutting blocks were analysed to check varus/valgus alignment, flexion/extension alignment, the amount of planned resection from both the femoral and tibial bones and the size of the components. Information from all the separate centres was sent to a central data processing base for analysis.

Results were calculated comparing the differences between the planned and performed cuts for each of the different variables studied. Graphs demonstrate the differences in the alignment between that planned by the surgical navigation system and what was actually carried out by the instrumented cuts.

Based on the data obtained from the multicentre study we have concluded that the planned position of the implants using the standard instruments was similar to that using the Vector Vision Navigation System. We believe that it is safe to proceed with surgical navigation total knee arthroplasty using the P.F.C.x total knee prosthesis with Image Guided Surgery and a further multicentre study is currently underway evaluating this.

Before proceeding to longer-term studies, we have studied the early clinical results of a new mobile-bearing total knee prosthesis in comparison with an established fixed-bearing device. Patients requiring bilateral knee replacement consented to have their operations under one anaesthetic using one of each prosthesis. They also agreed to accept the random choice of knee (right or left) and to remain ignorant as to which side had which implant. Outcomes were measured using the American Knee Society Score (AKSS), the Oxford Knee Score (OKS), and determination of the range of movement and pain scores before and at one year after operation.

Preoperatively, there was no systematic difference between the right and left knees. One patient died in the perioperative period and one mobile-bearing prosthesis required early revision for dislocation of the meniscal component.

At one year the mean AKSS, OKS and pain scores for the new device were slightly better (p < 0.025) than those for the fixed-bearing device. There was no difference in the range of movement.

We believe that this is the first controlled, blinded trial to compare early function of a new knee prosthesis with that of a standard implant. It demonstrates a small but significant clinical advantage for the mobile-bearing design.

Aim: Failed primary hip arthroplasty often results in significant loss of host bone. Revision surgery may require bone grafting to restore bone stock prior to insertion of a new cup. A two to five year follow up of one method of acetabular revision for severe bone stock loss is presented

Materials and Methods: Seventeen patients had acetabular revision with the use of impacted morcellised bone and a cage reconstruction with a cemented cup. The average age at the time of revision was 62. All patients were followed prospectively with regular X-rays. A variety of cages were employed and bone graft was hand morcellised from femoral heads or cadaver distal femurs.

Introduction: Patient education and informed consent are areas of clinical practice that are taking an ever-increasing proportion of a surgeon’s time and effort. The expectation is that this trend will continue, as medical malpractice litigation becomes more commonplace. Patients are also requiring increased access to medical information to help facilitate decisions about their healthcare. With the increasing use of computers and improvements in technology modules to aid patients’ understanding have become available and may prove useful in patient education.

Method: A computer-based multimedia module of total hip replacement (THR) has been developed. These involve three-dimensional (3D), animated computer graphics with text and spoken word. A questionnaire based on educational models was designed to test ease of use and patients’ comprehension after viewing the module.

Results: A pilot study involved 20 patients each awaiting elective surgery for THR. The results showed a good comprehension and understanding of the nature of the surgery and the possible complications.

Conclusions: We have shown that a 3D-multimedia patient education module improved patients’ understanding of THR surgery and its possible complications. The use of 3D multimedia modules has the potential to save the surgeon time whilst ensuring that his/her patients have given informed consent to their forthcoming surgery. It is hoped that better-informed consent may equate to a reduction in medical malpractice activity and thus insurance premiums.

Introduction: There has been significant development in computer technology in recent years and this has led to applications in orthopaedic surgery. Of particular interest is computer assisted joint arthroplasty to enable accurate insertion of the components based on CT generated images of the patient’s bones.

Methods: Twenty-five patients have undergone computer assisted total knee arthroplasty using a computer guidance system (Vector Vision, Brain Lab, Munich) implanting a PFC cruciate retaining total knee replacement (TKR) (Depuy, Leeds). Pre-operative CT scans were obtained from each patient and alignment and sizing were calculated before surgery. Intra-operatively, an infrared camera tracked the instruments and the patient’s limb was accurately mapped in space by surface matching the bone and comparing it with the CT scan. For the purpose of the study the computer generated alignments and sizing were evaluated along with the use of traditional instruments and stored in a database.

Results: These have been evaluated comparing computer assisted and instrumented knee arthroplasty. Variables measured include the AP femoral cuts, rotational femoral alignment, and tibial axis alignment in AP and lateral planes.

Conclusions: Computer assisted orthopaedic surgery has undergone a rapid development in the last 18 months to enable real-time intra-operative images to be viewed in a moving limb with a degree of accuracy previously not possible. The use of this technology may lead to more accurate alignment of hip and knee prostheses and therefor help to reduce wear in the long-term.

Introduction: Infected hip arthroplasties have usually been managed with either one or two stage revisions using antibiotic impregnated cement to fix the components. The use of cementless fixation has been less widely reported. The results on the femoral side have been less encouraging.

Aim: To present the short to medium term results of cementless revision for infected hip arthroplasty.

Methods: Ten patients who had undergone cementless revisions for infected hip arthroplasties have been followed prospectively. There were eight males and two females with an average age of 67 years. Nine of the 10 patients were treated with two-stage revisions with one female undergoing a one-stage revision for medical reasons. The diagnosis of sepsis was made on the basis of bacterial cultures and positive histology from all patients. Removal of the prosthesis was followed by the administration of intravenous antibiotics for six weeks and, in some, cases oral antibiotics for several months. The reconstructions were undertaken following the Girdlestone’s arthroplasties with a range from eight weeks to three years, (with the exception of the one stage exchange).

Results: The patients were examined from 18 to 64 months after the surgery with none lost to follow-up. All prostheses remained in situ with improvements in the Charnley and Oxford hip scores. There had been no recurrence of infection and no clinical or radiological evidence of loosening.

Discussion: Debate still exists about the merits of one-stage versus two-stage reconstruction for an infected hip arthroplasty. The use of antibiotic-impregnated cement has been recommended, especially for the femoral component. This series demonstrated that cementless reconstruction for infected hip arthroplasty was successful in providing an infection free, stable hip in the short to medium term.

Purpose: As part of the step-wise introduction of a meniscal-bearing total knee replacement (Oxford TMK) we needed to know, before proceeding to longer term studies, whether its early clinical results were at least as good as those of an established fixed bearing device (AGC).

Material and Methods: With ethical approval, patients requiring bilateral knee replacement for osteoarthritis consented to have the operations under one anaesthetic using one of each prosthesis; to accept random choice of knee; and to remain ignorant which side was which. American Knee Society Scores, Oxford Knee Scores, ROM and pain scores were to be recorded preoperatively and at one year. By January 2001, 40 patients had reached one year and data is available for 36.

Results: Preoperatively there was no difference between the two knees. One patient died in the peri-operative period.

Results at one year (TMK first): AKSS(Knee) 91.6 / 84.1 (p=0.003), OKS 39.8 / 37.6 (p=0.006), ROM 104 / 104 (p=0.364), Pain (AKSS) 47.3 / 41.7 (p=0.01), Pain (OKS) 3.5 / 2.9 (p=0.006).

Conclusion: The TMK performed as well as the AGC. Its AKSS, OKS and pain scores were significantly better. We believe this controlled, blinded trial is the first to have compared the function of a new knee prosthesis with a standard implant before marketing; and the first to have demonstrated a significant clinical advantage for a meniscal-bearing over a fixed bearing TKR. The comparison of bilateral implants in the same patient can reveal significant differences while putting at risk many fewer subjects than would be needed for a classical twocohort RCT.

We assessed the efficacy of intraoperative frozen-section histology in detecting infection in failed arthroplasties in 106 hips and knees. We found inflammatory changes consistent with infection (an average of one or more neutrophil polymorphs or plasma cells per high-power field in several samples) in 18 cases; there was a significant growth on bacterial culture in 20 cases. Compared with the bacterial cultures, the frozen sections provided two false-negative results and three false-positive results (sensitivity, 90%; specificity, 96%; and accuracy, 95%). The positive predictive value was 88%, the negative value, 98%. These results support the inclusion of intra-operative frozen-section histology in any protocol for revision arthroplasty for loose components.