Abstract

Principles of bone preservation and restoration of biomechanical alignment should be followed during revision total hip arthroplasty (THA). Where possible, conservative femoral revision techniques and even reconstructive de-escalation involving using primary stems should be considered. This study aims to investigate the outcome of patients who have undergone conservative femoral revision THA in our Institution.

We retrospectively identified patients from our Institution's revision arthroplasty database who had cemented, or un-cemented primary stems implanted during revision THA of a previous stemmed femoral implant. Our primary outcome measure was all-cause re-revision THA with a secondary outcome measure of improvement in Oxford hip score (OHS). Radiographic evidence of stem loosening and post-op complications were recorded.

Between 02/12/2014 to 12/12/2019, there were 226 patients identified with a mean follow up of 2 years (1–5 years). The majority of cases were represented by Paprosky type 1 (63%) and type 2 (25%) femoral defects. There were 45 patients (20%) who underwent impaction bone grafting (IBG) and 43 patients (19%) who had a cement in cement (CinC) femoral revision and cemented primary stem in 137 (60%), 1 uncemented stem with no IBG or CinC revision. Kaplan Meier survival for all-cause re-revision THA was 93.7% (95% CI: 88.3 – 100) at 3 years. The reasons for re-revision included 4 periprosthetic fractures, 4 dislocations, 1 deep infection, 1 loosening of femoral component and 1 loosening of acetabular component. Pre- and post-operative OHS scores were available in 137 hips (60%) with a mean improvement of 13. Radiographic review revealed 7% of cases with evidence of loosening in 1 or more Gruen zones.

Our early results support the use of conservative femoral revision THA techniques where appropriate, with low complication and re-revision rates. Revisions using primary femoral components, where appropriate, should be considered in surgical planning to avoid unnecessary reconstructive escalation.

Background

Revision total hip arthroplasty (THA) is a challenging scenario following complex primary THA for developmental dysplasia of hip (DDH). This study envisages the long-term outcomes of revision DDH and the role of lateral structural support in socket fixation in these young patients who may require multiple revisions in their life-time.

Revision total hip arthroplasty (THA) is a challenging scenario following complex primary THA for developmental dysplasia of hip (DDH). Our study envisages the long-term outcomes of revision DDH and the role of lateral structural support in socket fixation in these young patients who may require multiple revisions in their life-time.

Hundred and eighteen consecutive cemented revision THAs with minimum follow up of 5 years following primary diagnosis of DDH operated between January 1974 and December 2012 were analysed for their clinical and radiological outcomes.

The mean follow-up of 118 patients was 11.0 years (5.1–39.6 years). The Kaplan Mier survivorship at 11 years with end point as revision for any reason was 89.8% (CI 81.1–98.4). Of 118 revisions, 88 acetabular revisions were for aseptic loosening. Out of the acetabular revisions, 21 had pre-existing structural bone grafts from primary surgery, of which only 3 needed structural re-grafting during revision. Amongst the remaining 18 hips, the lateral support from the previous graft facilitated revision with no requirement of additional structural graft. Sixty-three hips did not have any form of grafting during primary operation. Amongst them, 35 had bone grafting in revision surgery (18 structural grafting).

This study reports the largest number of revision THAs with primary diagnosis of DDH with the longest follow up. In our experience, the lateral support from the structural graft done in primary operation appears to have provided benefit in subsequent revision socket fixation.

Aims

The aim of this study was to determine whether patients with metal-on-metal (MoM) arthroplasties of the hip have an increased risk of cardiac failure compared with those with alternative types of arthroplasties (non-MoM).

Introduction: Revision hip arthroplasty for aseptic loosening of femoral component is successfully treated with impaction bone grafting technique. Owing to easier technique and shorter operative time, distally fixed non-cemented long stems have gained popularity in the present era. However, use of long stems could make subsequent re-revision difficult due to further bone loss. The standard length stem has been often critiqued due to apprehension of peri-prosthetic fracture.

This study aims to determine the long-term outcomes of the impaction bone grafting of the femur for aseptic loosening in revision hip arthroplasty using standard length C-stems. 168 total hip revisions of 162 patients with impaction bone grafting and cemented standard C-stem (done with standardized technique) between 1995 and 2008 at a tertiary referral centre were included. Revisions for infection and segmental bone defects were excluded.

Mean follow-up of the 168 revision hips was 10.5 years (range 5 – 19.1 years). 14 patients (8.3%) were re-revised, reasons being, persistent deep infection (1.8%), repeated dislocations (1.2%), cup loosening (4.8%) and stem loosening (1.2%). Only 1 patient (0.6%) was re-revised due to stem loosening alone. No peri-prosthetic fractures (intra-operative or post-operative) or stem breakage were identified.

Use of standard stem length in hip revisions with impaction bone grafting does not increase the risk of peri-prosthetic fractures, instead, reconstitutes the bone stock. This questions the conventional principle of bypassing the distal cavitation of femur by 2 cortical diameters with the use of long stem. In our experience, a good proximal femur support is key to performance of standard length cemented stems in revision for aseptic loosening irrespective of grade of distal cavitation for cavitatory defects of femur when treated with impaction bone grafting.

Background

One of the major concerns of hinge knees have been reported in literature is mechanical failure. Failure in the form of component fracture (2–10%) and hinge dislocation/ failure are worrisome. In addition, higher risk of aseptic loosening with hinge knee prosthesis has been attributed to stress transfer at bone cement interface.

In patients with primary hip replacement for previous infective arthritis the risk of recurrence of infection is of major concern. In addition, the safe time interval post infective arthritis for primary hip replacement is not known.

Clinical & radiological results of consecutive series of 80 primary hip replacements performed for septic / tuberculous arthritis at Wrightington hospital from 1970 to 2008. Data was collected till latest follow up. Re-infection or revision for any reason was considered as primary end point for survivorship.

Average age at primary hip replacement was 55.55 years (24 – 75). Mean follow up was 14.47 years (2–41). Twelve patients in septic hip group (n=42) needed revision out of which 6 (14%) were for infection. The survival rate for recent septic arthritis group (<10 years) was 60% at 7.5 years, whereas in old septic arthritis group (>10 years) it was 94.45% at 15.3 years, considering infection as end point. The survival rate was 60% for recent septic arthritis and 78.13% for old septic arthritis group over the same period of time considering revision for any reason as end point. In tuberculous group (n=38), the survival rate was 76.32% at 14.5 years of follow up, considering revision for any reason as end point.

Significantly high re-infection rate in patients with recent septic arthritis was noted. No recurrence of infection in patients with old septic arthritis. No reactivation of tuberculosis in tuberculous arthritis group.

This is the largest series with longest follow-up on primary total hip replacement for infective arthritis till date. Recent septic arthritis (<10Y) was a statistically high risk factor for recurrence of infection. Old septic arthritis is reasonably safe with 94.45% success rate at 15 years follow up. Old tuberculous arthritis is not a risk factor for hip replacement

The choice of stem length in total hip revision with impaction bone grafting of femur is essentially based upon the grade of cavitation of femur and surgeon's preference. The standard length stem has been often critiqued for the apprehension of peri-prosthetic fracture. Our study highlights the importance of proximal bone stock rather than distal cavitation in determining the length of femoral stem.

168 total hip revisions of 162 patients with impaction bone grafting and cemented standard C-stem (done with standardized technique) between 1995 and 2008 at a tertiary referral centre were included. Revisions for infection and segmental bone defects were excluded. Serial radiographs were retrospectively analysed by two people independently, using Endoklinik classification, Gruen zones and more and outcomes were analysed.

Mean follow-up of the 168 revision hips was 10.5 years (range 5 – 19.1 years). 14 patients (8.3%) were re-revised, reasons being, persistent deep infection (1.8%), repeated dislocations (1.2%), cup loosening (4.8%) and stem loosening (1.2%). Only 1 patient (0.6%) was re-revised due to stem loosening alone. No peri-prosthetic fractures or stem breakage were identified.

Use of standard stem length in hip revisions with impaction bone grafting doesn't increase the risk of peri-prosthetic fractures even during long term follow up period. This questions the principle of bypassing the distal cavitation of femur by 2 cortical diameters with the use of long stem. In our experience, a good proximal femur support aids in the performance of standard length cemented stems in revision for aseptic loosening irrespective of grade of distal cavitation for cavitory defects of femur treated with impaction bone grafting.

Distal femoral replacement is an operation long considered as salvage operation for neoplastic conditions. Outcomes of this procedure for difficult knee revisions with bone loss of distal femur have been sparsely reported.

We present the early results of complex revision knee arthroplasty using distal femoral replacement implant, performed for severe osteolysis and bone loss.

Retrospective review of clinic and radiological results of 25 consecutive patients operated at single centre between January 2010 and December 2014. All patients had single type of implant. All data was collected till the latest follow up. Re-revision for any reason was considered as primary end point.

Mean age at surgery was 72.2 years (range 51 – 85 years). Average number of previous knee replacements was 2.28 (range 1 to 6). Most common indications were infection, aseptic loosening and peri-prosthetic fracture. Average follow up was 24.5 months (range: 3–63 months). 1 patient died 8 months post-op due to unrelated reasons. Re-revision rate was 2/25 (8%) during this period. One was re-revised for aseptic loosening and one was revised for peri-prosthetic fracture of femur. Two other peri-prosthetic fractures were managed by open reduction and internal fixation. All 3 peri-prosthetic fractures occurred with low energy trauma.

It is noteworthy that there was no hinge or mechanical failures of the implant. Peri-prosthetic fracture in 12% of patients in this series is of concern. There are no similar studies to compare this data with. The length of the stem, type of fixation of the stem, weight of the distal femoral component of implant can be postulated as factors contributing to risk of peri-prosthetic fracture.

Introduction

Limb Length discrepancy after total hip replacement has been reported to happen in 1–27% of cases with differences up to 70mm. Occasionally revision THR has been used to achieve limb length equalisation, especially when patients are symptomatic with hip/back pain, neurologic symptoms or instability. However, in presence of a well-functioning, pain free hip without hip symptoms, revision THR for shortening can lead to problems with decrease in offset or stability. An option in these cases would be a distal shortening osteotomy of femur.

Structural bulk autografts restore the severe bone loss at primary hip arthroplasty in dysplastic hips and have shown to have good long term outcomes. There are only a few reports of revision arthroplasty for these sockets that fail eventually. We report on a series of such primary hips which underwent cemented revision of the socket for aseptic loosening and their outcomes.

A retrospective review was performed from our database to identify fifteen acetabular revisions after previous bulk autograft. The mean age at revision was 53.9 years (range 31–72.1). The mean duration between the primary and revision arthroplasty was 12.4 years (range 6.6 – 20.3). All procedures were done using trochanteric osteotomy and three hips also needed the femoral component revision. All fifteen hips needed re-bone grafting at the revision surgery to restore the new socket to the level of the true acetabulum. Of these ten hips had morsellised impaction allograft, and the remaining five also needing a structural bulk allograft.

Two sockets underwent re-revision at mean 7.5 years for aseptic loosening. One patient had a dislocation that was reduced closed. At a mean follow up of 5.7 years, one socket showed superior migration, but was stable and did not need further intervention. Two other sockets also showed radiological evidence of loosening, and are being closely monitored.

The medium term results of cemented acetabular revision in this younger age group are satisfactory, with repeat bone grafting being required to restore the true acetabular position. Though the primary arthroplasty with bulk bone graft recreates the acetabular bone stock, significant bone loss due to the mechanical loosening of the socket needs to be anticipated in revision surgery.

Introduction

Primary hip replacement in young active patients is on the increase. Due to the demands set by the patient, implants used in this patient group should have a proven long-term clinical and radiological outcome. We report our results in patients under the age of 50 using the C-Stem femoral component – a cemented triple tapered polished stem.

Financial impact and patient satisfaction with four different anticoagulants for hip and knee arthroplasty in patients with a previous history of VTE- A prospective randomised trial

Introduction

We present the outcome of 297 acetabular revisions using bone grafting and cemented acetabular components in 297 patients, with a mean follow-up of 8 years 3 months (5–20 years).

Introduction

We aim to assess the functional outcome, patient perceived satisfaction and implant survival at a mean follow up of 13[10–16] years following revision knee replacement.

The C-Stem in its design as a triple tapered stem, is the logical development of the original Charnley flat-back polished stem. The concept, design and the surgical technique cater for a limited slip of the stem within the cement mantle transferring the load more proximally.

Five thousand two hundred and thirty three primary procedures using a C-stem have been carried out since 1993. We reviewed all 621 cases that had their total hip arthroplasty before 1998.

Sixty nine patients (70 hips) had died and 101 hips had not reached a ten-year clinical and radiological follow-up and had not been revised. Thirty-two hips had been revised before 10 years, none were revised for aseptic stem loosening and no stems. The indications for revision were Infection in 4, dislocation in 3, aseptic cup loosening in 24 and unexplained pain in 1.

The remaining 418 hips had a mean follow-up of 12 years (range 10–15 years). There were 216 women and 173 men, and 34 patients had bilateral LFAs. The patients' mean age at surgery was 53 years (range 16–83 years). Thirty four hips had been revised at the time of review. The reasons for revision were infection in 5, dislocation in 2, aseptic cup loosening in 24 and 1 for neuralgia paraesthetica where the stem was well fixed. Two hips were revised for stem fracture.

There were no revisions for stem loosening but 2 stems were revised for fracture - both with a defective cement mantle proximally. The clinical results are very encouraging and they support the concept of the Charnley cemented low friction arthroplasty, but place a demand on the understanding of the technique and its execution at surgery.

Introduction

We aim to assess the functional outcome, patient satisfaction and implant survival at a mean follow up of 13[10–16] years following revision for infected total knee replacement.

Introduction

Modern processing techniques in bone banking are thought to decrease the presence of allogenic material in bone. This project was performed to observe any changes in peripheral blood lymphocyte subsets in response to allografted bone used in revision hip replacement.

We describe the association between post-operative femoral stem radiological appearances and aseptic failure of THA (total hip arthroplasty) following a retrospective review of records and radiographs of all patients attending for follow-up between August 2002 and August 2003 who had a cemented Charnley femoral stem and either a cemented polyethylene acetabular cup inserted. Femoral stem aseptic loosening was defined either by findings at revision surgery, the definite radiographic loosening criteria of Harris or progressive endosteal cavitation across zones as described by Gruen. Well-fixed control THAs were defined as those that demonstrated none of the radiographic features of aseptic loosening or ‘at risk’ signs as described by Wroblewski. Parameters measured were: Alignment, Barrack grade of cementation, cement mantle width of the cement mantle and the presence and width of any radiolucent lines.

Sixty-three hips were entered into the aseptic failure group and 138 into the control group. The alignment of the femoral stem was not associated with failure (p=0.283). Thickness of the cement mantle was statistically associated with failure in Gruen zones 6 (p=0.040) and Gruen zone 7 (p=0.003). A significant association for the presence of radiolucent lines was found for Gruen zones 3 (p=0.0001) and 5 (p=0.0001). The grade of cementation as measured by the Barrack grade was strongly associated with failure for grades C (p=0.001) and D (p=0.001).

This study has demonstrated that easily applied radiological criteria can be used to identify ‘at risk’ Charnley THAs from the immediate post-operative AP radiograph.

The Osteoprotegerin/RANK/RANKL system has been implicated in the biological cascade of events initiated by particulate wear debris and bacterial infection resulting in periprosthetic bone loss around loosened total hip arthroplasties (THA). Individual responses to such stimuli may be dictated by genetic variation and we have studied the effect of single nucleotide polymorphisms (SNPs) within these genes.

We performed a case control study of the Osteoprotegerin, RANK and RANKL genes for possible association with deep sepsis or aseptic loosening. All patients included in the study were Caucasian and had had a cemented Charnley THA and polyethylene acetabular cup. Cases consisted of 91 patients with early aseptic loosening and 71 patients with microbiological evidence at surgery of deep infection. Controls consisted of 150 THAs that were clinically asymptomatic for over 10 years and demonstrated no radiographic features of aseptic loosening. DNA samples from all individuals were genotyped using Taqman allelic discrimination.

The A allele (p<0.001) and homozygous genotype A/A (p<0.001) for the OPG-163 SNP were highly associated with aseptic failure. Additionally, the RANK-575 (C/T SNP) T allele (p=0.004) and T/T genotype (p=0.008) frequencies were associated with aseptic failure. No statistically significant relationship was found between aseptic loosening and the OPG- 245 or OPG-1181 SNPs.

When the septic group was compared to controls, the frequency of the A allele (p<0.001) and homozygous genotype A/A (p<0.001) for the OPG-163 SNP were statistically significant. No statistically significant relationship was found between septic failure and the OPG- 245, OPG-1181 or RANK-575 SNPs.

Aseptic loosening and possibly deep infection of THA may be under genetic influence to candidate susceptibility genes. SNP markers may serve as predictors of implant survival and aid pharmacogenomic prevention of THA failure.

Aim: To identify the microbiology of infected knee arthroplasty, emerging patterns of resistance over the last decade, and suggest appropriate empirical treatment.

Methods: A retrospective analysis was conducted of 121 patients with microbiologically proven infection, who underwent revision TKA between 1994–2008. The causative organism was identified from microbiological samples and the corresponding sensitivities recorded. The data was then collated to determine the most common causative organisms, changing patterns of antibiotic resistance over the time frame, and the antibiotics currently most effective at treating deep infection. A theoretical model combining gentamicin with other antibiotics was used to determine the most effective antibiotics for use as empirical treatments.

Results: Coagulase negative Staphylococcus (CNS) was the most common causative organism (49%). Staphylococcus aureus (SA) accounted for 13% of cases. The prevalence of CNS appears to be increasing, while that of SA and other organisms is decreasing. Vancomycin and teicoplanin were the most effective antibiotics with overall sensitivity rates of 100% and 96% respectively. Levels of resistance were significantly higher among the antibiotics commonly used in the community. Antimicrobial resistance was higher when the causative organism was CNS, suggesting that MRSE is becoming a problem in knee arthroplasty. Our theoretical model showed that gentamicin combined with vancomycin would be the most effective empirical treatment.

Conclusion: Understanding the microbiology of deep infection of the knee allows surgeons to treat this complication as effectively as possible. Vancomycin and tei-coplanin appear to be the most effective antimicrobials, with relative invulnerability to the development of resistance. Given the effectiveness of these antibiotics, the use of vancomycin in gentamicin bone cement, combined with IV teicoplanin potentially allows for infected knee arthoplasties to be treated with a one-stage procedure. The rational use of antibiotics may help limit the amount of antibiotic resistance which develops in the future.

Patients with a history of septic arthritis or tuberculosis (TB) of the hip frequently develop secondary osteoarthritis (OA). These patients present a challenge for having joint replacement because of abnormal bone development, the possibility of re-infection, soft tissue problems and their life-style (more active than patients with old age arthritis). We retrospectively review a decent group of 55 cases where one stage cemented total hip arthroplasty was performed with history of old hip infection by a team of surgeons at Wrightington Hospital, Lancashire, UK from 1970 to 2008. The purpose of this study is to find the survival analysis with revision (for infection) as the end stage. There are 33 females and 22 males aged from 25 to 75 yrs (mean 52 years). 21 patients had proven or probable tuberculous infection, 29 had the past history of old septic hip, and the remaining 5 had recent septic hip (i.e., less than 5 years). The patients are followed for between 1 to 23 years (mean 10 years). Pre-operatively, 25 patients had arthrodesis while 24 patients had moderate to severe secondary OA. 3 patients had dysplastic acetabulum, 2 patients had shallow acetabulum and 1 had Avascular Necrosis (AVN). In 33 cases, intra-operative tissue samples didn’t grow any organism, 2 samples grew Staphylococcus aureus, 2 samples grew Coagulase Negative Staphylococcus (CNS), 1 grew pseudomonas, samples were not sent in 9 cases, laboratory did not process the sample in 1 case and no documentation found in 3 cases. Cement with antibiotics was used in 45 patients (Gentamicin alone in 37 cases, Gentamicin and Vancomycin in 3 cases, Gentamicin, Fucidic Acid and Eryth-romycin in 2 patients, Gentamicin, Vacncomycin and Streptomycin in 1 patient, Gentamicin and Streptomycin in 1 case and Gentamicin, Vacncomycin and Amoxycillin in 1 patient). Mostly intravenous antibiotics (3 doses of Cefuroxime) were given, but in few cases with old TB, anti-tuberculous treatment was started pre-operatively and continued for 3 months post-op. In 16 patients either antibiotics were not given or not documented to be given. Failure happened in 2 cases of positive intra-op sample culture with Staphylococcus aureus, 1 patient with pre-op aspiration which showed pseudomonas and in 2 cases where tissue sample showed no growth. 8 patients had revision of at least one of the components for aseptic loosening. The 2 failed cases with positive culture with Staphylococcus aureus had post operative antibiotics and extra antibiotics in cement. Both cases had early wound healing issues.

Conclusion: We can conclude that total hip arthroplasty is safe in old cases of septic or tuberculous hips, provided appropriate antibiotic cover. We have some evidence that total hip replacement can be carried out in cases of recent infection of hip but level of evidence is not very great as we don’t have a large sample of such patients.

‘Force-closed’, tapered, polished, collar-less stems, (e.g. C-stem, Exeter), are designed to subside in response to expansion of the cement/bone complex over time. Above a certain threshold, distal migration may predict medium-to-long-term failure of ‘shape-closed’ stems. However, no such threshold exists for ‘force-closed’ stems, and these may continue to migrate after 3 years. We believe that the tendency towards stabilisation 2–3 years postoperatively, could be the best predictor of good long-term performance.

Twenty OA patients (12F, mean age 66.6 years) were recruited for primary hip replacement with beaded C-stem femoral components. Tantalum marker beads were injected into the proximal femur, and stems were inserted using CMW1 cement and the latest generation cementing technique via a posterior approach: 17, and a lateral, trochanteric approach: 3. RSA X-ray examinations were performed at 1 week, 6 weeks, and at 3, 6, 12, 24 and 36 months postoperatively. The UmRSA system was used to measure and analyse the radiographs. At 36M the mean stem centroid subsidence was 1.05 mm and had levelled off to a low rate. The mean internal rotation of 2.5° at 36M had not significantly changed during the final year (p = 0.08).

At 36M the mean posterior migration of the stem centroid was 0.54 mm (rate of 0.11 mm/y) and posterior migration of the femoral head was 1.66 mm (rate of 0.25 mm/y).

At 36M the mean subsidence rate was very low and the mean posterior migration was about one third of that reported for another RSA study of the C-stem. Although the mean internal rotation was greater than that reported for the Exeter stem, there was no significant change during the final year. These low rates of migration at 3 years are consistent with the good results found in clinical studies of this femoral component.

Infection in total knee replacement is a devastating complication. Current literature supports two-stage revision as the gold standard treatment. The alternative single stage procedure has been reported to have favourable results. We assessed the early clinical results of single stage revision for infected total knee replacement.

Between February 2005 and August 2007, 12 patients had revision total knee replacement for infection by the senior authors at two centres. In the majority of the patients, the infective organism was isolated by arthroscopic synovial biopsy prior to revision. Standard single stage procedure included the explantation, debridement and re-implantation of the prosthesis. All the patients received intravenous antibiotics for six weeks and oral antibiotics were continued for further 6 weeks. All the patients had the inflammatory markers monitored during follow-up.

Significant improvement was noted in the SF-12 PCS, WOMAC pain and stiffness scores at the latest follow-up. None of these patients required re-revision. Radiological evaluation was done using the Knee Society system. None of the knees showed evidence of progressive loosening. Radio-opaque lines were found around the stems and were present on immediate post-operative radiographs; this did not indicate loosening or infection at a mean follow-up of two years.

Early clinical and radiological results of the single stage revision for infected total knee replacement appear to be promising. One operation, one anaesthetic and quicker recovery are the advantages for the patient and with the reduced hospital stay it is cost-effective. The problems of stiffness in the knee and muscle wasting with cement spacer are avoided.

Background: Since Sir John Charnley introduced bio-clean air operating techniques such as the “body exhausting” system and a bio-clean air operating theatre to reduce the risk of infection3), total hip replacement has become one of the safest and most successful procedures in orthopaedic surgery and has benefited numerous people suffering from arthritis all over the world. However, deep infection is still undoubtedly one of the most serious complications after total hip arthroplasty (THA). It is still controversial whether one or two stage revision should be indicated for deeply infected hip replacement.

Purpose: The aim of this study was to identify the influential factors in one stage revision THA for deep infection with a long-term follow-up.

Methods: One stage revision THA for deep infection was carried out in 273 joints on 262 patients by the senior author between 1974 and 2000. All infected hip replacements were primarily treated with one stage revision THA regardless of micro organisms at the authors’ unit as far as sufficient bone stock for socket fixation was available in the acetabulum. This study included 162 revisions in 154 patients for which a minimum follow-up of five years (range 5 to 28 years; average 12.3 years) had been done. Fifty-two cases (32.1 %) had had discharging sinus by the time of revision surgery for infection.

Results: One hundred and thirty eight (85.2 %) hips were free of infection at the time of the latest follow-up. Twenty cases (12.3 %) had reoperation for recurrent infection. Four hips (2.5 %) maintained their implants with the evidence of infection. Twenty-two cases (13.6 %) showed radiological loosening. Thirteen cases (8.0 %) were revised again for reasons other than infection (12 for aseptic loosening and one for dislocation). Bone stock did not have significant influence on infection control while it did affect mechanical outcome. The cement-bone interface was an affecting factor for not only the mechanical survival of implants but also the cure of infection. Neither discharging sinus nor gram-negative microorganism was considered as a contraindication.

Conclusion: This study presented the longest follow-up with a large number of cases in revision THA for deep infection. The results suggested that shielding medullary space with antibiotic-loaded cement was important for treatment of infected THA.

Introduction: “Force-closed”, tapered, polished, collarless stems, (e.g. C-stem, Exeter), are designed to subside in response to a gradual expansion of the cement/bone complex.

Above a certain threshold, distal migration may predict medium-to-long-term failure of “shape-closed” (collared, textured) stems. However, no such threshold exists for “force-closed” stems, and these may continue to migrate after 3 years. We believe that the tendency towards stabilisation 2–3 years postoperatively could be the best predictor of good long-term performance.

Method: Twenty OA patients (12F, mean age 66.6 years) were recruited for primary hip replacement with beaded C-Stem femoral components. Tantalum marker beads were injected into the proximal femur, and stems were inserted using CMW1 cement and the latest generation cementing technique via: a posterior approach (17), and a lateral, trochanteric approach (3). RSA X-ray examinations were performed at 1 week, 6 weeks, and at 3, 6, 12, 24 and 36 months postoperatively. The UmRSA system was used to measure and analyse the radiographs.

Results: By 36M the mean stem subsidence (1.05 mm) had levelled off to a low rate, and the mean internal rotation (2.5°) had not significantly changed during the final year (p = 0.08). The mean posterior migration of the stem centroid was 0.54 mm and posterior migration of the femoral head was 1.66 mm (0.25 mm/y during final year).

Discussion: At 36M the mean subsidence rate was very low, and the mean posterior migration was about one third of that reported by Sundberg et al. (BHS Meeting, 2007). Although the mean internal rotation was greater than that reported for the Exeter stem, it had stabilised during the final year. These low rates of migration at 3 years are consistent with the good results found in clinical studies of this femoral component.

Introduction: The tribiological properties of bearing surfaces are one of the main topics in discussion in the orthopaedic research. Hard-on-hard bearings are one of the ways to reduce wear rates. Modern hard-on-hard bearing low wear rates depend on the correct pairing of bearing surfaces and strict manufacturing tolerances in surface roughness, clearance, and roundness.

There have been some concerns in using ceramic bearings, particularly regarding the fracture rate and their subsequent management. Hence, we present here 2 similar cases that highlight the catastrophic failure of metal head when used subsequently to treat the complication of ceramic fractures in Total Hip Arthroplasty (THA).

Case Details: Two patients underwent primary THA at different centres with ceramic-on-ceramic bearing. After an initial asymptomatic period of 2 years, ceramic fracture occurred in both the cases, which were subsequently replaced by metal-on-polyethylene bearings by the primary surgeons. One year after the revision of bearings, both the patients developed severe pain and discomfort, which on further investigation revealed massive metallosis, wear of the metal head and aseptic loosening of the acetabular components with cavitation in acetabulum.

Both the patients underwent revision THA under the senior author at our tertiary centre-Wrightington Hospital. Intraoperatively near total erosion of the metal head was noted with more than one litre of black, dense material collection in and around the hip joint revealing extensive metallosis. The acetabular cup was grossly loose and significant loss of bone stock was noted due to metallosis.

Single stage revision surgery was performed with impaction bone grafting for deficient acetabulum and cemented components were used. At one-year follow-up none of the cases have shown any further wear or complications.

Conclusion: One of the main objectives of successful THA is to improve implant longevity. To achieve this understanding the mechanisms of wear between the interacting surfaces is extremely important. The use of ceramic head is good, but there is always a risk of fracture. We do not recommend using metal heads in cases with prior ceramic fractures, as the wear of metal is most likely to occur as it is an ongoing process due to the residual ceramic debris. Hence in these difficult scenarios we recommend usage of ceramic-on-polyethylene as a safe option to prevent catastrophic erosion of metal head and improve implant longevity.

Introduction: The evolving pattern of bacterial resistance at septic revision surgery to the common antibiotics used during total hip arthroplasty is described.

Methods: A retrospective review of 72 case notes and microbiology data inclusive of bacterial sensitivity profiles was undertaken between January 2002 and April 2007. Data collected was combined with a previous study to demonstrate bacteriology trends over the last thirty years (327 cases). Antibiotic sensitivities to the two common infectious agents, Staphylococcus aureus and coagulase negative staphylococi were formulated into a hypothetical model combined with Gentamycin sensitivity, a constant factor (the sole antibiotic in bone cement), to assess the efficacy of the combination of antibiotics used in primary arthroplasty.

Results: When compared to previous microbiology data percentage isolates of each bacterium were found to be similar, confirming that the infectious agents at septic revision had remained the same, and were the common contaminants at primary surgery. The results also demonstrated an overall trend of increased resistance of the major organisms to the major classes of antibiotics used. Staphylococcus aureus and coagulase negative staphylococci were routinely tested against nine common antibiotics, inclusive of Gentamycin. Critical findings showed that the regimen used in routine primary surgery covers only 67% of staphylococcus infections (cefuroxine and Gentamycin); combinations that showed increased coverage included clindamycin and Gentamycin, and rifampicin plus Gentamycin, providing in excess of 100% coverage, and Erythromycin and Gentamycin, coverage in excess of 80%.

Discussion: Consequently we can recommend from prospective analysis of common infections at septic revision, that the antibiotic regimen at primary surgery is not sufficient to prevent infection (in isolation). Dynamic variations continuously develop in bacteria; genetic make up is regulated to optimise survival, continuously detrimentally affecting the efficacy of antibiotics against the power of super bugs, indicating a pattern in need of continuous monitoring and review.

Introduction: The triple tapered polished cemented C-stem has evolved from the study on long-term results of the Charnley design, when first fractures of the stem and then proximal strain shielding of the femur and stem loosening were identified as the continuation of the same process. The design utilises the common engineering principle of male (stem) and female (cement) tapers engaging under load, loading the proximal femur.

Methods and Results: The C-stem was tested extensively and introduced into clinical practice in December 1993. Up to the end of October 2007, 4558 have been implanted in primary operations.

None of the 4558 stems have been revised for aseptic loosening or fracture.

The patient’s mean age at surgery was 48 years (range 15–76), and 171 hips with a mean follow-up of 11 years (range 10–13.7) have now passed 10 years. There were 97 females and 64 males in this group with 10 patients having bilateral C-stems. The main underlying pathologies were Primary Osteoarthritis 30%, Developmental Dysplasia of the hip 27% and Avascular Necrosis of the hip 19%.

Clinical outcome graded according to d’aubigne and postel for pain, function and movement has improved from 3.1, 3.1 and 2.9 to 5.9, 5.7 and 5.6 respectively.

A good quality proximal femur had been maintained in 47.1% and improved in a further 29.9%.

Discussion: The results achieved with the C-Stem design and technique are encouraging and support the concept of loading the proximal femur, but place a demand on the understanding of the technique and its execution at surgery.

Introduction: Revision arthroplasty using the impaction grafting technique is an increasingly popular technique. The lost bone stock is replaced rather than substituted with ever increasing amounts of metal. There have been many advances in the understanding of this technique in recent years. It has recently been shown that washing of the graft improves the biomechanical strength, bony ingrowth and biocompatibility of morsellised allograft bone. The aim of this study was to identify the most efficacious method of washing morsellised allograft in the operating room.

Methods: Fresh frozen femoral heads identified for research purposes were randomly divided into four groups. Group A was washed using a serial dilution technique at 37°C, group B serial dilution at 60 °C, group C pulsed lavage wash at 37°C and group D pulsed lavage wash at 60 °C. Three-gram samples of each femoral head were taken prior to washing. The heads were then washed according to the grouping. The unwashed and washed morsellised bone was then assessed for the presence of protein, haemoglobin, DNA and lipid using spectrophotometric analysis techniques. The removal of these marrow components from the femoral heads in each group was assessed as a proportion of the original content.

Results: All washing techniques removed a large proportion of the marrow load of the femoral heads. The most efficacious technique was washing by serial dilution (removal rate 67.5–87.4%). Washing by pulsed lavage removed less marrow (28.4–80.9%). Protein showed the highest removal rate (80.9–86.4%) and haemoglobin the lowest (28.4–67.5%). Removal of lipid was most affected by temperature with a larger proportion removed at 60°C as compared to 37°C.

Conclusion: We conclude that the most efficient method of washing morsellised allograft bone for impaction grafting is by serial dilution with fluid at 60°C. This information should improve the results of impaction grafting, as it is known that cleaner bone results in improved biomechanical stability, enhanced biological compatibility and accelerated bony ingrowth.

Hip arthroplasty has its true genesis in 1962 when the Charnley Total Hip was first implanted. The system comprised a stainless steel femoral stem with fixed 22,225mm head articulating against an all polyethylene acetabular cup. Both components were fixed in position with acrylic bone cement. There have been a number of changes in design, materials and surgical technique but the essential concept remains the same. The system was widely used by both senior and junior surgeons. Numerically implantations peaked at ~45,000 per annum in the late1980’s and is still at around ~25,000 per annum in the mid 2000’s. Geographically the system was used in all five continents. Patients varied widely both in age, activity, and diagnosis. It would therefore seem an appropriate vehicle to examine the variations in results of total hip replacement by patient profile, geography, and era of implantation.

A search was carried out on the US NCBI website for publications reporting on results with the Charnley system up to the end of 2002, and which comprised a follow-up of more than 10 years, and gave survivorship data. This resulted in 28 papers with 14 countries of origin available for review. For all studies basic data such as age and diagnosis, range implantation dates, likely specific design of prosthesis, origin of study and number in study was either reported or could be deduced. A ten year survivorship was reported in 16 studies for stem and cup and 7 for stem only. If the longest follow-up was considered for each study then 18 reported on stem and cup (9392 hips, implanted 1962–92) and 15 on stem only (4243 hips, implanted 1966–91). A total of 11 studies had four of more points on a survivorship curve, seven with stem and cup, four with stem only.

There are a number of points of interest in this data. The first is that with one exception the performance is remarkably consistent as shown by the survivorship curves. There is no significant difference in the survival rates from different centres, countries, and with implantation dates ranging from 1962 through to 1992. Secondly, there appears to have been little or no change in the average age of patients with implant date. There is some evidence to indicate from the 10 year data that failure rate per year is lower in older patients but does not seem to be affected by implantation date. The latter despite the fact that both surgical technique and component design changed over the 30 year implantation period. A further observation is that the failure rate per year is lower in studies with greater numbers of patients.

The general conclusion from this review is that the Charnley Total Hip is remarkably consistent in its performance both over time and location of implantation. Its performance also seems to have been affected very little by changes in technique or design.

Introduction: Freezing and storage of fresh frozen femoral heads destined for use in revision hip arthroplasty is thought to result in graft cell death. Washing of the graft following the morsellisation process also removes a large proportion of the marrow content of the allograft. However, the immunological load of the impaction allografting process remains unknown. The aim of this study was to investigate the immune response by observing any changes in peripheral blood lymphocyte subsets in response to allografted bone used in revision hip replacement

Methods: 87 patients were entered into this prospective study and grouped according to whether impaction allograft was used or not. Venous blood samples were collected pre-operatively and at set time intervals up to one year post-operatively. Using flow cytometry, analysis of venous blood allowed counts of the following cells: Helper T-lymphocytes, cytotoxic T-lymphocytes, memory T-lymphocytes, naïve T-lymphocytes, Natural Killer cells and B-lymphocytes.

Results: All patients had a successful outcome at one year. 50 patients with radiologically defined host-graft union were compared with 37 patients who did not receive allograft. Pre-operatively, a significant difference (p=0.03) was found between the groups of patients with respect to Natural Killer cells but other subsets showed no significant difference. Post-operatively the significant difference between Natural Killer cells resolved. T-helper lymphocytes, cytotoxic lymphocytes, memory T-lymphocytes and naïve T-lymphocytes in both groups showed decreases in values immediately post surgery, recovering to normal values within 6 weeks post-surgery. The allograft group showed significant increases from baseline in cytotoxic T-lymphocytes at 6 months (p< 0.01) and memory T-lymphocytes one year postoperatively (p=0.04). B-lymphocyte numbers did not alter significantly from baseline.

Conclusion: Cytotoxic T-lymphocytes recognise HLA-class I molecules which are present on all nucleated cells and have been implicated in having a role in osteoclast regulation. Memory T-lymphocytes are produced after a naïve T-lymphocyte is exposed to an antigen. The observed increases of these subsets were not observed in the non-grafting group suggesting the allografted bone had elicited an immunological response. At 12 months all grafts appeared radiologically stable and the immunological response may have been beneficial to the outcome.

Impaction grafting with morsellised allograft is becoming the treatment of choice for revision arthroplasty, especially in the younger patient. The optimum treatment of the graft prior to impaction has not been determined. Some groups wash the graft prior to impaction and others do not. Washing of graft has been shown to enhance bone ingrowth in an animal model, however the reasons for this remain unclear. The aim of this study was to identify any underlying cellular cytotoxicty of fresh frozen allograft bone before and after washing.

Paired samples of washed and unwashed morcellised FFH allograft were taken during revision hip arthroplasties. Washing was performed by 4 consecutive rinses in 300ml warmed saline, the bone being filtered between each exchange of saline. Contact cytotoxicity assays involved culture of cell lines in direct contact with bone samples. Quantitative cytotoxicity assays utilised culture media conditioned with the bone samples and subsequent assessment of cell metabolism and viability using both dimethylthiazol (MTT) and neutral red (NR) assays. Assays were performed with human osteoblastic (MG63) and fibroblastic (HSF) cell lines.

Nine pairs of samples were analysed. Contact assays demonstrated a clear zone of cellular inhibition around the unwashed bone samples. Quantitative assays were performed in triplicate for each cell type and both MTT and NR assays giving 108 paired assay results. 88.9% of pairs (92/108) showed cytotoxicity in the unwashed sample. No washed samples demonstrated cytotoxicity. When grouped by assay and cell type, analysis of means showed statistically significant differences between washed and unwashed samples in MG63-NR (p=0.0025), HSF-NR (p=0.0004) and MG63-MTT (p=0.008). The difference observed in the HSF-MTT assays did not reach statistical significance (p=0.06).

Unwashed FFH allograft can be cytotoxic to human osteoblastic and fibroblastic cell lines in vitro. This suggests that allograft should be washed prior to impaction in order to optimise the biological compatibility.

The Triple-tapered cemented polished C-Stem has evolved from the study of long-term results of the Charnley low-frictional torque arthroplasty when the first fractured stem and then proximal strain shielding of the femur and stem loosening were identified as the continuation of the same process- the lack or loss of proximal stem support.

The concept, design and the surgical technique cater for a limited slip of the C-stem within the cement mantle transferring the load more proximally. With a follow-up past 12 years and 4063 primary procedures there have been no revisions for aseptic stem loosening and no stem is radiologically loose.

We have reviewed 1008 primary C-Stem hip arthroplasties performed by 23 surgeons with a minimum of 5 years clinical and radiological follow-up. The mean follow-up was 7 years (range, 5 – 12) and the mean age at surgery was 57 years (range (15 – 85). In 58% the underlying pathology was primary osteoarthritis, 20% congenital dysplasia, 10% quadrantic head necrosis, 5% rheumatoid arthritis, 5% slipped upper femoral epiphysis and 4% protrusio acetabulae.

The concept of the triple tapered stem is validated radiologically with an improved proximal femoral bone stock in over 20% of cases and a maintained bone stock in 60%.

There were no post-operative complications within 1 year in 87% and no late complications (after 1 year) in 91%. The main late complications were 3.9% aseptic cup loosening, 1% infection and 0.8% dislocation. There were no aseptic loose stems.

Twenty-eight hips have been revised (2.8%), 3 for infection, 2 for dislocation and 23 for aseptic cup loosening. There were no revisions for aseptic stem loosening.

The results support the concept but place a demand on the understanding of the technique and its execution at surgery.

Introduction: The long term success of impaction grafting depends on the remodelling process during incorporation. This project was designed to characterise any differences in the biochemical markers of bone turnover following revision hip arthroplasty performed with or without impaction grafting.

Methods: 87 patients undergoing revision hip arthroplasty were entered into this prospective study and grouped according to whether impaction allograft was used or not. Biochemical markers of bone turnover were assessed pre-operatively and post-operatively on day 2, day 9, week 6, 6 months and 1 year. Osteocalcin, pro-collagen type-I N-terminal propeptide and bone specific alkaline phosphatase were measured as bone formation markers. C-telopeptide, pyridinoline and deoxypyridinoline were measured as bone resorption markers.

Results: All patients had a successful radiological and clinical outcome at one year. 50 patients with radiologically defined host-graft union were compared with 37 patients who did not receive allograft. Markers of bone formation tended to rise by day 9 but the rise in osteocalcin was delayed in the graft group and was significantly lower at 6 months in comparison to the non-graft group (p=0.002). Alkaline phosphatase levels remained significantly elevated at one year in the graft group (p=0.027) whilst levels in the non-graft group had normalised. Markers of bone resorption also rise in both groups but with no significant differences between the groups.

Discussion: Following impaction grafting, new bone formation may be delayed in comparison to revisions performed without graft. The pattern of markers of bone resorption did not differ significantly between the groups suggesting that there is no large scale resorption of the impacted allograft in these cases.

These results provide a biochemical insight into the bone formation and bone resorption processes during allograft incorporation.

Introduction: There is an increasing trend for autologous blood transfusion in hip and knee replacement and we therefore felt the need to properties of the fluid reinfused.

Objectives of the study: The study objective was to determine the volume and Haemoglobin content of the reinfused blood.

Materials and methods: We prospectively studied 108 patients with primary Hip and knee arthroplasty. The drained blood was reinfused within 6 hours as recommended by the manufacturer. The volume of the drained and reinfused fluid was measured in millilitres.. The Haemoglobin (Hb.) of the patient was measured preoperatively and postoperatively in recovery. The Hb. of the drained blood and reinfused blood were also measured.

Results : The mean volume of the drained blood in the hip replacement group was 180.6 ml. while that of the reinfused blood was 132.7 ml. The mean volume of the drained blood in the knee group was 372.78 ml. while that of the reinfused blood was 362.76 ml.

The mean Haemoglobin of the reinfused blood in the hip group was 6.9 gm/dl significantly lower (p< 0.05) than the drained blood Hb. of 10.9. Similarly the Haemoglobin of the blood reinfused in knee replacements was significantly lower at 6.8 gm/dl. (p< 0.001). This was less than half of the average Hb. content of homologous blood transfusion.

Conclusion: The Haemoglobin content of the reinfused blood in Hip and knee replacement was quite low to be considered as a replacement for homologous blood transfusion and further studies may be required to confirm the efficacy of reinfusion drainage compared to homologous blood transfusion.

Introduction: There is an increasing trend for autologous blood transfusion in hip and knee replacement and we therefore felt the need to properties of the fluid reinfused.

Objectives of the study: The study objective was to determine the volume and Haemoglobin content of the reinfused blood.

Methods: We prospectively studied 108 patients with primary Hip and knee arthroplasty. The drained blood was reinfused within 6 hours as recommended by the manufacturer. The volume of the drained and reinfused fluid was measured in millilitres.. The Haemoglobin (Hb.) of the patient was measured preoperatively and postoperatively in recovery. The Hb. of the drained blood and reinfused blood were also measured.

Results: The mean volume of the drained blood in the hip replacement group was 180.6 ml. while that of the reinfused blood was 132.7 ml. The mean volume of the drained blood in the knee group was 372.78 ml. while that of the reinfused blood was 362.76 ml.

The mean Haemoglobin of the reinfused blood in the hip group was 6.9 gm/dl significantly lower (p< 0.05) than the drained blood Hb. of 10.9. Similarly the Haemoglobin of the blood reinfused in knee replacements was significantly lower at 6.8 gm/dl. (p< 0.001). This was less than half of the average Hb. content of homologous blood transfusion

Discussion: The Haemoglobin content of the reinfused blood in Hip and knee replacement was quite low to be considered as a replacement for homologous blood transfusion and further studies may be required to confirm the efficacy of reinfusion drainage compared to homologous blood transfusion

Introduction: We performed a retrospective case control study in 80 patients who under went revision hip surgery at our unit.

Methodology: Group A (40 patients), received tranexamic acid and intra-operative cell salvage. Group B (40 patients) a matched control did not receive these treatments. Each group was divided into 4 sub groups; revision of both components, revision of components + bone grafting, revision acetabular component +/− bone grafting and revision femoral component +/− bone graft.

Results: In group A the total number of units transfused was 139 compared to 52 in group B. This represents a reduction in blood usage of 37%. The mean amount of blood transfused from cell salvage in each group was 858mls, 477mls, 228mls and 464mls. There was a significant difference in the amount of blood returned between the groups (p< 0.0001). In the control group 37 patients needed transfusion, in the study group 22 (p< 0.0001). At our unit a cost analysis calculation has shown total revenue saving of £88,000 and a potential saving throughout the trust of £316,688 per year.

Discussion: To our knowledge this is the first study to examine the use of cell salvage and tranexamic acid in revision hip surgery. Our results show that a significant reduction in blood transfusion can be made using this technique. It is vital that blood conserving strategies are developed so that future revision surgery can continue.

Fresh frozen femoral head (FFH) allograft is commonly used in impaction grafting for revision hip arthroplasty and long term success has been demonstrated by some groups. The optimum treatment of the graft prior to impaction has not yet been determined. Some groups wash the graft prior to impaction and others do not. Washing of the graft has been shown to improve bone ingrowth in a bone chamber animal model however the reasons for this remain unclear. The aim of this study was to identify any underlying cellular cytotoxicty of fresh frozen allograft bone before and after washing.

Samples of morcellised FFH allograft were taken during revision hip arthroplasties prior to impaction grafting. Paired samples, taken before and after washing were taken from each case. Washing was performed by 4 consecutive washes in 300ml warmed saline, the bone being filtered between each exchange of saline. Cytotox-icity was assessed for all samples using both contact and extract assays. Contact assays involved culture of cell lines in direct contact with bone samples. Extract assays utilised culture media conditioned with bone samples and subsequent quantitative assessment of cell metabolism and viability using both dimethylthiazol (MTT) and neutral red (NR) assays. All assays were performed using both human osteoblastic (MG63) and fibroblastic (HSF) cell lines.

Nine pairs of samples were analysed for cytotoxicity using both cell lines. Contact assays demonstrated a clear zone of cellular inhibition around the unwashed bone samples. Extract assays were performed in triplicate for each cell type and both MTT and NR assays giving 108 paired assay results. 88.9% of pairs (92/108) showed cytotoxicity in the unwashed sample. No washed samples demonstrated cytotoxicity. When grouped by assay and cell type, analysis of means showed statistically significant differences between washed and unwashed samples in MG63-NR (p=0.0025), HSF-NR (p=0.0004) and MG63-MTT (p=0.008). The difference observed in the HSF-MTT assays did not reach statistical signifi-cance (p=0.06).

In conclusion, we have shown that unwashed FFH allograft can be cytotoxic to human osteoblastic and fibroblastic cell lines in vitro. This suggests that allograft should be washed prior to impaction in order to optimise the biological compatibility.

Introduction: The long term success of impaction grafting depends on the remodelling process during incorporation. This project was devised to characterise any differences in the biochemical markers of bone turnover following revision hip arthroplasty performed with or without impaction grafting.

Methods: 87 patients were entered into this prospective study and grouped according to whether impaction allograft was used or not. Biochemical markers of bone turnover were assessed pre-operatively and post-operatively on day 2, day 9, week 6, 6 months and 1 year. Osteocalcin, procollagen type-I N-terminal propeptide and bone specific alkaline phosphatase were measured as bone formation markers. C-telopeptide, pyridinoline and deoxypyridinoline were measured as bone resorption markers.

Results: All patients had a successful outcome at one year. 50 patients with radiologically defined host-graft union were compared with 37 patients who did not receive an allograft. Markers of bone formation tended to rise by day 9 but the rise in osteocalcin was delayed in the graft group and was significantly lower at 6 months in comparison to the non-graft group (p=0.002). Alkaline phosphatase levels remained significantly elevated at one year in the graft group (p=0.027) whilst levels in the non-graft group had normalised. Markers of bone resorption also rise in both groups but with no significant differences between the groups.

Discussion: Following impaction grafting, new bone formation may be delayed in comparison to revisions performed without graft. The pattern of markers of bone resorption did not differ significantly between the groups suggesting that there is no large scale resorption of the impacted allograft in these cases.

These results provide a biochemical insight into the bone formation and bone resorption processes during allograft incorporation.

Introduction: Bone stock and cement-bone interface in revision total hip replacement (THR) for deep infection have never been investigated in the literature, while they are known to be important for aseptic loosening. The purpose of this study was to assess preoperative bone stock and immediate postoperative cement-bone interface as factors affecting infection control and mechanical outcome after revision THR for deep infection.

Methods: This study included 115 cases in which revision THR with antibiotic-loaded cement was operated for infected hip replacement by a single surgeon with minimal follow-up of five years (range 5–27 years). Preoperative bone stock was classified into four grades (Grade 0: No bone loss, Grade 1: Demarcation, Grade 2: Localized cavitation, Grade 3: Extensive bone loss). The immediate postoperative cement-bone interface was also graded into four categories (Grade A: White-out, obscure interface, Grade B: Clear line, no measurable gap, Grade C: Gap> 1mm, Grade D< 1mm). These two factors were analysed with regard to infection control and mechanical survival of implants after surgery.

Results: Bone stock did not have significant influence on infection control while it affected mechanical outcome. The cement-bone interface was an affecting factor for not only the mechanical survival of implants but also the cure of infection.

Discussion: There was a good chance of curing the infection even with extensive bone loss. Good cement fixation was an important factor with regard to infection control as well as the mechanical survival of implants. The results suggested that it might be important to shield the medullary space from the infected joint space with antibiotic-loaded cement.

Introduction: In the United Kingdom, the wait for hip or knee joint replacement surgery can be particularly long. There are conflicting research accounts whether debilitating symptoms, such as pain and the effects on physical function and quality of life deteriorate or remain the same in individuals who are on the waiting list for hip or knee joint replacement. This study was conducted to investigate the severity of pain, level of physical function and quality of life amongst adults with osteoarthritis awaiting hip or knee joint replacement.

Methods: A longitudinal study was undertaken in the North West of England during 2003–2005. A total of 105 patients listed for primary hip or knee joint replacement were recruited, interviewed at baseline, and followed-up at three, six and nine months, or until their joint replacement. Measurement tools used were a visual analogue scale (VAS), Western Ontario McMaster’s University (WOMAC) Osteoarthritis Index and the Medical Outcomes Study Short Form Health Survey (SF-36).

Results: High levels of pain and poor physical function and quality of life were experienced by patients on the waiting list for joint replacement. At the three month follow-up (n=84) changes in VAS pain scores (0.6; 95% CIs mean difference 0.3,1.0); WOMAC pain scores (1.2 (95% CIs mean difference 0.7, 1.8) and WOMAC physical function scores (4.8; 95% CIs mean difference 2.8, 6.7) were significantly worse compared to baseline. However, there were minimal changes in quality of life as measured by the SF-36 while on the waiting list.

Discussion: The often long wait for joint replacement surgery and deterioration in pain and physical function has highlighted the need for active management by health professionals while patients are on the waiting list. There needs to be a clinical reassessment of patients by health professionals while on the waiting list for joint replacement.

Bone morphogenic proteins (BMPs) are members of the transforming growth factor beta (TGF-beta) family and play a central role in bone formation. These morpho-gens are known to be present in bone matrix however the characteristics of their release during the grafting process has not previously been defined. The aim of this study was to determine the release BMP-7 (osteogenic protein; OP-1) from cancellous allograft that occurs during impaction grafting for revision hip arthroplasty.

Forty, 10mm cubes of cancellous bone were accurately cut from the central region of 7 fresh frozen femoral heads. The cubes were centrifuged and washed to remove the marrow contents. The cubes were then individually washed and the fluid assayed for BMP-7 activity using a commercially available enzyme linked immuno-sorbent assay kit (Raybiotech Inc.). The cubes were then divided into 4 groups with samples from each femoral head in each group. Each group was subjected to strain of either 20%, 40%, 60% or 80% using a material testing machine. The cubes were then individually washed again and the wash fluid analysed for BMP-7 activity.

BMP-7 activity was found to be present in all groups. Release of BMP-7 was found to increase with increasing strain. At 80% strain the mean concentration of BMP-7 released (830 pg/g) was 58% greater than that released at 60% strain (527 pg/g), 150% greater than the concentration at 40% strain (333 pg/g) and 476% greater than at 20% strain (144 pg/g). The differences between release at 80% and 40% strain and between 80% and 20% strain were statistically significant (p=0.036, p=0.002).

Activity of BMP-7 in fresh frozen cancellous allograft bone has not previously been demonstrated. This study shows that the freezing and storage of femoral heads allows some maintenance of biological activity. Furthermore we have shown that BMP-7 may be released in proportion to the strain applied to the bone. This confirms that the process of impaction of bone morsels during revision hip arthroplasty may release BMPs that could aid in the incorporation and remodelling of the allograft.

Fifty-seven revision total knee arthroplasties were performed in our hospital using the TC3 system between 1995 and 1997. Twelve patients died. Forty-five patients were followed up for an average of 5.6 years (range 4 – 7 years). No patients were lost to follow-up.

All patients were clinically and radiologically evaluated. A postal patient satisfaction questionnaire was completed. Two patients were revised; one for infection and one for instability. Survivorship using revision as the end point was 93.3% at 7 years.

Indications for revision were infection (4;9%), instability (38;84%), pain and stiffness (3;7%). 32 (71%) patients were satisfied with their outcome, 7 (16%) were noncommittal and 6 (13%) were disappointed at 5 years. We have analysed the 13 dissatisfied patients and highlight the lessons learned.

Pain and stiffness are not good indications for revision; insert thickness of more than 17.5mm is suggestive of elevation of the joint-line; instead the femoral component should be distalised; step wedges should be used in preference to angular wedges; Always long stem the tibial implant if augments are used; stems should be canal filling with adequate grip on the diaphysis.

We suggest the above lessons we have learned from our initial revision arthroplasty learning curve may correlate to the clinical outcome of this small group of dissatisfied patients.

Introduction: In attempting to unravel the complex cellular responses leading to prosthetic loosening investigators have been limited to studying gene expression of extracellular molecules about which most is known whereas new microarray technology allows simultaneous expression profiling of thousands of genes from a complex sample such as the membrane formed around loosened hip prostheses.

Methods: Two groups of 8 patients were recruited who have undergone primary total hip arthroplasty for osteoarthritis and subsequently developed either septic or aseptic loosening +/− osteolysis. The control group consisted of one group of 5 patients with the same initial diagnosis who had undergone identical procedures, developed no clinical or radiological signs of aseptic or septic loosening, but had come to revision surgery for other complications as defined by the Swedish Hip register: fracture without previous osteolysis, dislocation, technical error, implant fracture, polyethylene wear or pain. Periprosthetic membrane was harvested at the time of revision surgery and subjected to RNA extraction. cDNA was then synthesized and hybridised to a Human Genome u95 Genechip ® array which contains a complete set of known human genes. Data normalisation, data filtering and pattern identification was performed using Genechip®3.1 software (Affymetrix, Santa Clara, CA).

Results: This has revealed the involvement of a large number of genes coding for transcriptional regulators upstream from the extracellular and cell-cell signalling molecules already known to be involved in osteolysis and deep infection and which may ultimately control the responses to wear particles and bacterial challenge. Differential expression of genes involved in cell survival and death, cell growth regulation, cell metabolism, inflammation and immune response was found. Most interestingly pathways for control of local bone resorption and inflammatory response have been shown to be highly activated.

Conclusions: The identification of these new pathogenetic mechanisms of total hip replacement failure make new indicators of disease susceptibility and prognosis plus new drug targets direct possibilities.

Introduction: We describe the association between postoperative femoral stem radiological appearances and aseptic failure of THA (total hip arthroplasty).

Methods: A retrospective review of records and radiographs of all patients attending for follow-up between August 2002 and August 2003 who had a cemented Charnley femoral stem and either a cemented polyethylene acetabular cup inserted. Femoral stem aseptic loosening was defined either by findings at revision surgery, the definite radiographic loosening criteria of Harris or progressive endosteal cavitation across zones as described by Gruen. Well-fixed control THA’s were defined as those that demonstrated none of the radiographic features of aseptic loosening or ‘at risk’ signs as described by Wroblewski. Parameters measured were: Alignment, Barrack grade of cementation, cement mantle width of the cement mantle and the presence and width of any radiolucent lines

Results: 63 hips were entered into the aseptic failure group and 138 into the control group. The alignment of the femoral stem was not associated with failure (p=0.283). Thickness of the cement mantle was statistically associated with failure in Gruen zones 6 (p=0.040) and Gruen zone 7 (p=0.003). A significant association for the presence of radiolucent lines was found for Gruen zones 3 (p=0.0001) and 5 (p=0.0001). The grade of cementation as measured by the Barrack grade was strongly associated with failure for grades C (p=0.001) and D (p=0.001).

Discussion and conclusion: This study has demonstrated that easily applied radiological criteria can be used to identify ‘at risk’ Charnley THA’s from the immediate post-operative AP radiograph.

Previous attempts to assess the comfort and protection afforded by surgical gowns have been extremely simplistic and limited in their nature relying on a single and subjective linear scoring system. We have performed a comfort assessment comparison between the Charnley exhaust suit, disposable gown plus visor and the Stryker Steri-Shield system using a newly developed objective multi-dimensional validated ergonomic tool.

A prospective, comparative study was conducted using a modification of the Comfort Rating Scales (CRS) designed to measure wearable comfort of computer devices during physical activity across 6 dimensions. These dimensions are emotion, attachment, harm, perceived change, movement and anxiety.

10 theatre staff were recruited to the study and completed modified CRS scores on three separate occasions after having worn a disposable surgical gown plus mask with visor, a Charnley exhaust suit and a Stryker Steri-Shield system. The total mean CRS for a disposable gown plus visor was 16.1 with a mean dimensional score of 2.7 (range: 0.2 – 8.4), for the Charnley system the values were 51.4 and 8.6 (range: 5.9 – 12.8) respectively and for the Stryker Steri-Shield 15.4 and 2.6 (range: 0.8–5.6).

Although disposable, impermeable gown plus visor or the Steri-Shield system provide a similar level of comfort, the modified CRS has demonstrated that over 6 dimensions of measurable comfort the Steri-Shield system provides the least variation in comfort and as such may offer the best combination of comfort, protective qualities and form or style of personal protection systems for lower limb arthroplasty operations.

Purpose Coagulase negative staphylococci (CNS) have been one of the major pathogens responsible for prosthetic joint infections, and are showing increasing multiple-antibiotics resistance. Intact cell mass spectrometry (ICMS), based on the analysis of bacterial surface proteins, has been recognised as a new technique for identification of micro-organisms. The aim of this study was to evaluate the ability of ICMS for species level identification of clinical CNS isolates.

Method A total of 50 CNS strains from revision joint replacement operations were studied. ICMS and commercial identification kits were used for identification of those CNS. The commercial kits were used following the manufacturer’s recommendations. For ICMS, single colonies were smeared onto five spots on a sample slide. After drying, a 1 μl of aliquot of matrix solution was added to each spot. Analysis of strains was performed using a Kompact MALDI 2 linear, time of flight mass spectrometer and 3-ns pulse width nitrogen laser light. Combined spectra were constructed from 100 shots at each spot on the sample slide.

Results In this study, the commercial kit did not require any special equipment, but required overnight incubation and could not identify at least seven strains. On the other hand, the ICMS method was rapid, accurate and highly reproducible. The mass: charge spectra produced by ICMS contained potential biomarker peaks that could be used for species level identification.

Conclusions ICMS has the potential as a powerful tool for species level identification of clinical CNS isolates in terms of rapidity, accuracy and cost effectiveness. This study suggested that ICMS is a possible new method of identifying causative organism in infected joint replacements.

Introduction: Non-steroidal anti-inflammatory drugs (NSAIDs) are inhibitors of cyclooxygenase activity and are potential therapeutic agents in the prevention of aseptic loosening. Cigarette smoking is a risk factor for decreased proximal femur bone density. We investigated whether the clinical variables of NSAID usage and cigarette smoking are possibly linked to aseptic loosening around total hip arthroplasty (THA).

Methods: Retrospective review of records and radiographs of all patients attending for follow-up between August 2002 and 2003 who had undergone THA. Age, gender, primary and revision surgery details, radiographic parameters as detailed above, smoking history and NSAID usage history were recorded. Logistic regression analysis was used to determine the presence of associations.

Results: 224 patients were recruited to the study: 143 to the control group with a mean time of THR survival of 14.6 years and 81 to the aseptic group with a mean time to THR failure of 5.1 years. 130 patients had never smoked, 69 were ex-smokers and 25 were smokers (average of 15.5 cigarettes/day). 13.6% of patients in the study group were smokers and 10.5% in the control group. The average duration of NSAID usage pre-operatively was 3.4 years and post-operatively was 4.4 years. Using the logistic regression model, amount of cigarettes smoked, years as a non-smoker and length of usage of NSAID were not found to be associated with aseptic loosening

Discussion and conclusions: We found no such statistically significant relationship with regards to smoking habit or NSAID usage as either protective or risk factors.