How to manage treatment failure in prosthetic joint infection.

BACKGROUND: Management for prosthetic joint infections remains a challenging area for both infectious diseases and orthopaedic surgery, particularly in the setting of treatment failure. This is compounded by a lack of level 1 evidence to guide approaches. The optimal management of prosthetic joint infections requires a multi-disciplinary approach combined with shared decision making with the patient. AIMS: This article describes the approach to prosthetic joint infections in the setting of treatment failure. SOURCES: Narrative review based on literature review from PubMed. There was no time limit on the studies included. In addition, the reference list for included studies were reviewed for literature saturation with manual searching of clinical guidelines. Management approaches described incorporate evidence- and eminence-based recommendations from expert guidelines and clinical studies, where applicable. CONTENT: The surgical and antimicrobial approaches for prosthetic joint infections are described for first-line treatment of prosthetic joint infections and approaches in the event of treatment failure. Management approaches are based on an understanding of the role the biofilm plays in the pathogenesis of prosthetic joint infections. The management of these infections aims to fulfil two key goals: to eradicate the biofilm-associated microorganisms and, to maintain a functional joint and quality of life. In treatment failure, these goals are not always feasible, and the role of the multi-disciplinary team and shared-decision making are prominent. IMPLICATIONS: Prosthetic joint surgery is a high-volume surgery, and the demand for this surgery is continually increasing. With this, the number of infections requiring expert care will also increase. Eminence-based management approaches have been established to guide treatment failure until knowledge gaps in optimal management are addressed by well-designed, clinical trials.

What Is the Risk of THA Revision for ARMD in Patients with Non-metal-on-metal Bearings? A Study from the Australian National Joint Replacement Registry.

BACKGROUND: There are increasing reports of corrosion between the femoral head and trunnion in primary conventional THA, resulting in metal particulate release often termed trunnionosis. There may be heightened awareness of this condition because of severe soft-tissue reactions initially thought to be solely attributable to prostheses with a metal-on-metal (MoM) bearing surface. It is unclear what percentage of revisions for THA with non-MoM bearing surfaces can be attributed to trunnionosis and to what extent adverse reaction to metal debris (ARMD) seen with MoM bearings may also be seen with other bearing surfaces in THA. QUESTIONS/PURPOSES: We analyzed data from a large national registry to ask: (1) What is the revision risk for the indication of ARMD in patients with conventional THA and modern non-MoM bearing surfaces such as metal or ceramic-on-cross-linked polyethylene (XLPE) or ceramic-on-ceramic? (2) What prosthesis factors are associated with an increased risk of such revision? (3) What is the relative revision risk for ARMD in THAs with large-head MoM bearings, small-head MoM bearings, and non-MoM modern bearing surfaces? METHODS: The Australian Orthopaedic Association National Joint Replacement Registry (AOANJRR) longitudinally maintains data on all primary and revision joint arthroplasties, with nearly 100% capture. The study population included all THAs using modern bearing surfaces (defined as metal or ceramic heads-on-XLPE and ceramic-on-ceramic bearing couples) revised because of ARMD between September 1999 and December 2018. Prostheses with modular necks were excluded. The cumulative percent revision (CPR) because of ARMD was determined. The study group consisted of 350,027 THAs with a modern bearing surface, 15,184 THAs with a large-head MoM bearing (≥ 36 mm), and 5474 THAs with a small head MoM bearing (≤ 32 mm). The patients in the group who received the modern bearing surfaces were slightly older than the patients in the groups who received the large- and small-head bearing surfaces, with a mean age 68 years (SD 12) versus a mean age 63 years (SD 12), and a mean age 62 years (SD 11), respectively. There was a higher proportion of women in the modern bearing surface group; 55% (193,312 of 350,027), compared with 43% (6497 of 15,184) in the large-head MoM group and 50% (2716 of 5474) in the small-head MoM group. The outcome measure was the CPR, which was defined using Kaplan-Meier estimates of survivorship to describe the time to the first revision for ARMD at 17 years. Hazard ratios (HR) from Cox proportional hazards models, adjusting for age and sex, were performed to compare the revision rates among groups. The registry defines a revision as a reoperation of a previous hip arthroplasty in which one or more of the prosthetic components is replaced or removed, or one or more components is added. RESULTS: The CPR for ARMD for patients with a modern bearing surface at 17 years was 0.1% (95% confidence interval 0.0 to 0.1). After controlling for age and sex, we found that cobalt chrome heads, two specific prostheses (Accolade® I and M/L Taper), and head sizes ≥ 36 mm were associated with an increased risk of revision for ARMD. Metal-on-XLPE had a higher risk of revision for ARMD than ceramic-on-ceramic or ceramic-on-XLPE (HR 3.4 [95% CI 1.9 to 6.0]; p < 0.001). The Accolade 1 and the M/L Taper stems had a higher risk of revision than all other stems (HR, 8.3 [95% CI 4.7 to 14.7]; p < 0.001 and HR 14.4 [95% CI 6.0 to 34.6]; p < 0.001, respectively). Femoral stems with head sizes ≥ 36 mm had a higher rate of revision for ARMD than stems with head sizes ≤ 32 mm (HR 3.2 [95% CI 1.9 to 5.3]; p < 0.001).Large-head MoM bearings had a greater increase in revision for ARMD compared with modern bearing surfaces. The CPR for patients with a large-head MoM bearing at 17 years for ARMD was 15.5% (95% CI 14.5 to 16.6) and it was 0.1% for modern bearing surfaces (HR 340 [95% CI 264.2 to 438.0]; p < 0.001). Modern bearing surfaces likewise had a lower HR for revision for ARMD than did THAs with small-head MoM bearings, which had a 0.9% (95% CI 0.7 to 1.4) CPR compared with modern bearings from 0 to 9 years (HR 10.5 [95% CI 6.2 to 17.7]; p < 0.001). CONCLUSIONS: The revision risk for ARMD with modern bearing surfaces in THA is low. The Accolade 1 and the M/L Taper stem have a higher risk of revision for ARMD and cobalt-chrome heads, and head sizes ≥ 36 mm have a higher rate of revision than ≤ 32 mm head sizes. ARMD is a rare failure mode for THA with non-MoM bearings, but in patients presenting with unexplained pain with no other obvious cause, this diagnosis should be considered and investigated further. LEVEL OF EVIDENCE: Level III, therapeutic study.

Greater risks of complications, infections, and revisions in the obese versus non-obese total hip arthroplasty population of 2,190,824 patients: a meta-analysis and systematic review.

BACKGROUND: Obesity is an epidemic, especially in developed countries. This affects the general health of these patients, especially when they are having a major surgical procedure such as total hip arthroplasty (THA). Several articles have described the effects of obesity on THA with varying conclusions. This meta-analysis aims to compare the outcomes, complications, and peri-operative parameters of THA in the obese (BMI≥30 kg/m2) vs non-obese (BMI<30 kg/m2) population as well as a subgroup analysis of morbidly obese (BMI≥40 kg/m2) vs non-obese population. METHODS: A multi-database search was performed according to PRISMA guidelines. Data from studies assessing the outcomes and complications of THA in the obese and non-obese population were extracted and analyzed. RESULTS: Sixty-seven studies were included in this meta-analysis, consisting of 581,012 obese and 1,609,812 non-obese patients. Meta-analysis could not be performed on patient reported outcome measures due to heterogeneous reporting methods. Obese patients had a higher risk of all complications (OR = 1.53, 95%CI: 1.30-1.80, P < 0.001), deep infections (OR = 2.71, 95%CI: 2.08-3.53, P < 0.001), superficial infections (OR = 1.99, 95%CI: 1.55-2.55, P < 0.001), dislocations (OR = 1.72, 95%CI: 1.66-1.79, P < 0.001), reoperations (OR = 1.61, 95%CI: 1.40-1.85, P < 0.001), revisions (OR = 1.44, 95%CI: 1.32-1.57, P < 0.001), and readmissions (OR = 1.37, 95%CI: 1.15-1.63, P < 0.001). When sub-group analysis of morbidly obese (BMI≥40 kg/m2) patients was performed, the risks of all these parameters were even greater. CONCLUSION: Obese and morbidly obese patients are at higher risks of complications post THA than non-obese patients. Surgeons should be aware of these risks in order to counsel patients and adopt prophylactic strategies to reduce these risks where applicable.

Practice variation in total hip arthroplasty versus hemiarthroplasty for treatment of fractured neck of femur in Australia.

AIMS: Displaced femoral neck fractures (FNF) may be treated with partial (hemiarthroplasty, HA) or total hip arthroplasty (THA), with recent recommendations advising that THA be used in community-ambulant patients. This study aims to determine the association between the proportion of FNF treated with THA and year of surgery, day of the week, surgeon practice, and private versus public hospitals, adjusting for known confounders. PATIENTS AND METHODS: Data from 67 620 patients in the Australian Orthopaedic Association National Joint Replacement Registry (AOANJRR) from 1999 to 2016 inclusive were used to generate unadjusted and adjusted analyses of the associations between patient, time, surgeon and institution factors, and the proportion of FNF treated with THA. RESULTS: Overall, THA was used in 23.7% of patients. THA was more frequently used over time, in younger patients, in healthier patients, in cases performed on weekdays (adjusted odds ratio (OR) 1.27; 95% confidence interval (CI) 1.14 to 1.41), in private hospitals (adjusted OR 4.34; 95% CI 3.94 to 4.79) and by surgeons whose hip arthroplasty practice has a relatively higher proportion of elective patients (adjusted OR 1.65; 95% CI 1.49 to 1.83). CONCLUSION: Practice variation exists in the proportion of FNF patients treated with THA due to variables other than patient factors. This may reflect variation in resources available and surgeon preference, and uncertainty regarding the relative indication.

Cross-Linked Polyethylene for Total Hip Arthroplasty Markedly Reduces Revision Surgery at 16 Years.

BACKGROUND: Total hip arthroplasty (THA) is an effective operation for the management of end-stage hip osteoarthritis, but long-term success can be limited by wear of the polyethylene bearing surface. Cross-linking conventional polyethylene has resulted in lower wear rates and a reduction in bone lysis in both laboratory and clinical studies. The aim of this study was to compare the rates of revision between cross-linked polyethylene (XLPE) and conventional non-cross-linked polyethylene (CPE) at 16 years after THAs performed for the treatment of osteoarthritis. METHODS: We performed an observational study of data, from a national registry, on all patients who underwent THA for osteoarthritis in Australia from 1999 through December 31, 2016. The outcomes of THAs performed with CPE were compared with those of THAs performed with XLPE, along with an analysis of the effect of age, sex, femoral head size, the method of acetabular and femoral component fixation, and the reasons and types of revision. The principal outcome measure was the time to the first revision, determined using Kaplan-Meier estimates of survivorship. RESULTS: CPE was used in 41,171 procedures, and XLPE was used in 199,131. The mean ages of the men and women treated with CPE were 70.0 years (standard deviation [SD] = 9.9 years) and 72.5 years (SD = 9.7 years), respectively, whereas the men and women who received XLPE were slightly younger (mean age, 68.6 years [SD = 10.3 years] and 70.7 years [SD = 9.9 years], respectively. XLPE was associated with a lower rate of revision than CPE at 6 months, and this difference became more apparent with time. The 16-year cumulative percentage of revisions of the primary THAs was 11.7% (95% confidence interval [CI] = 11.1% to 12.3%]) in the CPE group and 6.2% (95% CI = 5.7% to 6.7%) in the XLPE group. The hazard ratio at 9 years was 3.02 (p = 0.001). CONCLUSIONS: The use of XLPE has resulted in a significant reduction in the rate of revision at 16 years following THA for osteoarthritis. This evidence suggests that the longevity of THA is likely to be improved, which may enable younger patients to undergo surgery, confident of a reduced need for revision in the long term. LEVEL OF EVIDENCE: Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

The use of femoral stems with exchangeable necks in primary total hip arthroplasty increases the rate of revision.

AIMS: Femoral stems with exchangeable (modular) necks were introduced to offer surgeons an increased choice when determining the version, offset and length of the femoral neck during total hip arthroplasty (THA). It was hoped that this would improve outcomes and reduce complications, particularly dislocation. In 2010, the Australian Orthopaedic Association National Joint Replacement Registry (AOANJRR) first reported an increased rate of revision after primary THA using femoral stems with an exchangeable neck. The aim of this study was to provide a more comprehensive up-to-date analysis of primary THA using femoral stems with exchangeable and fixed necks. MATERIALS AND METHODS: The data included all primary THA procedures performed for osteoarthritis (OA), reported to the AOANJRR between 01 September 1999 and 31 December 2014. There were 9289 femoral stems with an exchangeable neck and 253 165 femoral stems with a fixed neck. The characteristics of the patients and prostheses including the bearing surface and stem/neck metal combinations were examined using Cox proportional hazard ratios (HRs) and Kaplan-Meier estimates of survivorship. RESULTS: It was found that prostheses with an exchangeable neck had a higher rate of revision and this was evident regardless of the bearing surface or the size of the femoral head. Exchangeable neck prostheses with a titanium stem and a cobalt-chromium neck had a significantly higher rate of revision compared with titanium stem/titanium neck combinations (HR 1.83, 95% confidence interval 1.49 to 2.23, p < 0.001). Revisions were higher for these combinations compared with femoral stems with a fixed neck. CONCLUSION: There appears to be little evidence to support the continued use of prostheses with an exchangeable neck in primary THA undertaken for OA. Cite this article: Bone Joint J 2017;99-B:766-73.

Substantial rise in the lifetime risk of primary total knee replacement surgery for osteoarthritis from 2003 to 2013: an international, population-level analysis.

OBJECTIVE: To estimate and compare the lifetime risk of total knee replacement surgery (TKR) for osteoarthritis (OA) between countries, and over time. METHOD: Data on primary TKR procedures performed for OA in 2003 and 2013 were extracted from national arthroplasty registries in Australia, Denmark, Finland, Norway and Sweden. Life tables and population data were also obtained for each country. Lifetime risk of TKR was calculated for 2003 and 2013 using registry, life table and population data. RESULTS: Marked international variation in lifetime risk of TKR was evident, with females consistently demonstrating the greatest risk. In 2013, Finland had the highest lifetime risk for females (22.8%, 95%CI 22.5-23.1%) and Australia had the highest risk for males (15.4%, 95%CI 15.1-15.6%). Norway had the lowest lifetime risk for females (9.7%, 95%CI 9.5-9.9%) and males (5.8%, 95%CI 5.6-5.9%) in 2013. All countries showed a significant rise in lifetime risk of TKR for both sexes over the 10-year study period, with the largest increases observed in Australia (females: from 13.6% to 21.1%; males: from 9.8% to 15.4%). CONCLUSIONS: Using population-based data, this study identified significant increases in the lifetime risk of TKR in all five countries from 2003 to 2013. Lifetime risk of TKR was as high as 1 in 5 women in Finland, and 1 in 7 males in Australia. These risk estimates quantify the healthcare resource burden of knee OA at the population level, providing an important resource for public health policy development and healthcare planning.

Twelve-month mortality and functional outcomes in hip fracture patients under 65 years of age.

INTRODUCTION: There has been a recent call for improved functional outcome reporting in younger hip fracture patients. Younger hip fracture patients represent a different population with different functional goals to their older counterparts. Therefore, previous research on mortality and functional outcomes in hip fracture patients may not be generalisable to the younger population. The aims of this study were to report 12-month survival and functional outcomes in hip fracture patients aged <65 years and predictors of functional outcome. METHODS: Hip fracture patients aged <65years (range 17-64) registered by the Victorian Orthopaedic Trauma Outcomes Registry over four years were included and their 12-month survival and functional outcomes (Extended Glasgow Outcome Scale) reported. Ordered multivariable logistic regression was used to identify predictors of higher function. RESULTS: There were 507 patients enrolled in the study and of the 447 patients (88%) with 12-month outcomes, 24 (5%) had died. The majority of patients had no comorbidities or pre-injury disability and were injured via road trauma or low falls. 40% of patients sustained additional injuries to their hip fracture. 23% of patients had fully recovered at 12 months and 39% reported ongoing moderate disability. After adjusting for all key variables, odds of better function 12-months post-fracture were reduced for patients with co-morbidities, previous disability or additional injuries, those receiving compensation or injured via low falls. CONCLUSIONS: While 12-month survival rates were satisfactory in hip fracture patients aged under 65 years, their functional outcomes were poor, with less than one quarter having fully recovered 12 months following injury. This study provides new information about which patients may have difficulty returning to their pre-injury level of function. These patients may require additional or more intensive post-discharge care in order to fulfil their functional goals and continue to contribute productively to society.

Geographical variation in incidence of knee arthroscopy for patients with osteoarthritis: a population-based analysis of Victorian hospital separations data.

BACKGROUND/AIM: To evaluate the frequency and geographical variation in knee arthroscopy for adults (>25 years) with a concomitant diagnosis of osteoarthritis. METHODS: This was a retrospective cohort study of hospital separations involving an elective knee arthroscopy in public and private hospitals in Victoria, Australia. Participants included patients receiving knee arthroscopies with a diagnosis code indicating osteoarthritis (OA) from 1 July 2008 to 30 June 2009. Records were excluded if the patient was under 25 years or their arthroscopy involved a ligament reconstruction. Crude rates per 100 000 population and negative binomial regression offset by total knee arthroscopy volume were used to analyse differences by region. RESULTS: There were 9620 arthroscopic procedures meeting the inclusion criteria. There were 5500 (57.2%) admissions where the principal diagnosis was knee OA (gonarthrosis) and 3510 (36.5%) where the principal diagnosis indicated a mechanical derangement and there was a primary or associated diagnosis of OA. When we examined the incidence rate ratios (IRR) by region, after adjustment for relevant factors and accounting for the total knee arthroscopy volume within each region, we identified significant variation in knee arthroscopy rates for patients with OA. The region with the highest adjusted IRR was Barwon South Western (IRR: 1.26, 95% confidence interval (CI): 1.16-1.36) and the region with lowest adjusted incidence rate ratio was the Gippsland region (IRR: 0.89, 95% CI: 0.80-0.98). CONCLUSIONS: We identified considerable geographical variation in arthroscopies for people with OA across Victoria. Further investigation is needed to understand whether this variation is a reflection of differences in OA prevalence, clinical decision-making or access.

Knee surgery recovery: Post-operative Quality of Recovery Scale comparison of age and complexity of surgery.

BACKGROUND: Initial validation and feasibility for the Post-operative Quality of Recovery Scale (PQRS) was published in 2010. Ongoing validation includes studies to determine whether this scale can discriminate differences in recovery between cohorts. METHODS: A prospective cohort study included 61 patients, 18-40 years, and 61 patients, aged ≥ 65 years, undergoing knee arthroscopy under general anaesthesia; and 13 patients, aged ≥ 65 years, undergoing total knee replacement under general anaesthesia. Patients were assessed using the PQRS. Assessments were performed pre-surgery, at 15 and 40 min, 1 and 3 days, and 3 months after surgery. RESULTS: The effect of age was assessed by comparing young versus older arthroscopy patients. There were minimal differences in recovery profiles, other than for the nociceptive domain, where pain recovery was significantly better in the older arthroscopy patients (P < 0.001). The effect of surgery was assessed by comparing older patients undergoing knee arthroscopy with knee replacement patients. Recovery was significantly worse for the knee replacement group for cognition (P = 0.015), nociception (pain and nausea, P < 0.001), activities of daily living (P < 0.001), emotive recovery (P = 0.029), and all-domains recovery (P < 0.001). Despite differences in quality of recovery, satisfaction was high in all cohorts. CONCLUSIONS: Knee replacement had a large effect on recovery compared with knee arthroscopy. Age had minimal effect on recovery after knee arthroscopy. The study showed the ability of the PQRS to discriminate recovery in different domains.

The imaging and classification of severe pelvic ring fractures: Experiences from two level 1 trauma centres.

We describe the routine imaging practices of Level 1 trauma centres for patients with severe pelvic ring fractures, and the interobserver reliability of the classification systems of these fractures using plain radiographs and three-dimensional (3D) CT reconstructions. Clinical and imaging data for 187 adult patients (139 men and 48 women, mean age 43 years (15 to 101)) with a severe pelvic ring fracture managed at two Level 1 trauma centres between July 2007 and June 2010 were extracted. Three experienced orthopaedic surgeons classified the plain radiographs and 3D CT reconstruction images of 100 patients using the Tile/AO and Young-Burgess systems. Reliability was compared using kappa statistics. A total of 115 patients (62%) had plain radiographs as well as two-dimensional (2D) CT and 3D CT reconstructions, 52 patients (28%) had plain films only, 12 (6.4%) had 2D and 3D CT reconstructions images only, and eight patients (4.3%) had no available images. The plain radiograph was limited to an anteroposterior pelvic view. Patients without imaging, or only plain films, were more severely injured. A total of 72 patients (39%) were imaged with a pelvic binder in situ. Interobserver reliability for the Tile/AO (Kappa 0.10 to 0.17) and Young-Burgess (Kappa 0.09 to 0.21) was low, and insufficient for clinical and research purposes. Severe pelvic ring fractures are difficult to classify due to their complexity, the increasing use of early treatment such as with pelvic binders, and the absence of imaging altogether in important patient sub-groups, such as those who die early of their injuries.

Loss to follow-up after arthroplasty: a new use for registry data.

We assessed the outcome of patients who were lost to follow-up after arthroplasty by a single surgeon. The aim was to validate the surgeon's data set with the Australian Orthopaedic Association National Joint Replacement Registry and determine the outcome of those patients lost to follow-up. Prospective data on patient demographics, operative details and outcomes of the surgeon's 1192 primary unicompartmental knee arthroplasty (UKA) procedures were analysed. There were 69 knees in patients who were lost to follow-up, among whom the Registry identified 31 deaths and eight revisions. The cumulative percentage revision (CPR) at seven years using the additional Registry data was 8.8% (95% confidence interval (CI) 7 to 11). Using the surgeon's data, the CPR at seven years was 8% (95% CI 6.3 to 10.1) for the best-case scenario where loss to follow-up was excluded, and 16% (95% CI 13.8 to 19.4) for the worst-case scenario, where all patients lost to follow-up were deemed to have been revised. There was a significantly higher mortality rate in those patients lost to follow-up. This study demonstrates that a national joint registry can be used by individual surgeons to establish more accurate revision rates in their arthroplasty patients. This is expected to facilitate a more rigorous audit of surgical outcomes by surgeons and lead to more accurate and uniform reporting of the results of arthroplasty in general.

Ceramic-on-ceramic bearing surface and risk of revision due to dislocation after primary total hip replacement.

Dislocation is a common reason for revision following total hip replacement. This study investigated the relationship between the bearing surface and the risk of revision due to dislocation. It was based on 110 239 primary total hip replacements with a diagnosis of osteoarthritis collected by the Australian Orthopaedic Association National Joint Replacement Registry between September 1999 and December 2007. A total of 862 (0.78%) were revised because of dislocation. Ceramic-on-ceramic bearing surfaces had a lower risk of requiring revision due to dislocation than did metal-on-polyethylene and ceramic-on-polyethylene surfaces, with a follow-up of up to seven years. However, ceramic-on-ceramic implants were more likely to have larger prosthetic heads and to have been implanted in younger patients. The size of the head of the femoral component and age are known to be independent predictors of dislocation. Therefore, the outcomes were stratified by the size of the head and age. There is a significantly higher rate of revision for dislocation in ceramic-on-ceramic bearing surfaces than in metal-on-polyethylene implants when smaller sizes (< or = 28 mm) of the head were used in younger patients (< 65 years) (hazard ratio = 1.53, p = 0.041) and also with larger (> 28 mm) and in older patients (> or = 65 years) (hazard ratio = 1.73, p = 0.016).

Cone femoral prosthesis for osteoarthritis of the hip with femoral dysplasia.

PURPOSE: To assess the clinical and radiological outcomes of total hip replacement (THR) using the cone femoral prosthesis. METHODS: Four men and 15 women (26 hips) aged 19 to 78 (mean, 45) years underwent THR for osteoarthritis of the hip with femoral dysplasia using the cone femoral prosthesis. Only 17 patients (24 hips) were available for review. Pain and functional limitation were assessed using the Oxford hip score. Stable fixation by bone ingrowth was defined as no subsidence or radiolucent lines around the prosthesis. RESULTS: The mean follow-up duration was 50 (range, 25-92) months. The mean Oxford hip score improved from 44 (range, 32-54) preoperatively to 17 (range, 12-28) at the latest follow-up. Prosthesis survival was 100%. All prostheses showed stable integration with bony ingrowth and no measurable subsidence. 15 hips had excessive anteversion of 25 to 90 degrees. No patient had venous thromboembolism, deep prosthetic infections or dislocations. CONCLUSION: The cone prosthesis is less complex and expensive than the modular prosthesis. The early functional and radiological outcomes were excellent, with marked improvement in pain and function. This constitutes effective treatment for osteoarthritis of the hip with femoral dysplasia.

Is there a place for shelf acetabuloplasty in the management of adult acetabular dysplasia? A survivorship study.

We followed up 76 consecutive hips with symptomatic acetabular dysplasia treated by acetabular shelf augmentation for a mean period of 11 years. Survival analysis using conversion to hip replacement as an end-point was 86% at five years and 46% at ten years. Forty-four hips with slight or no narrowing of the joint space pre-operatively had a survival of 97% at five and 75% at ten years. This was significantly higher (p = 0.0007) than that of the 32 hips with moderate or severe narrowing of the joint-space, which was 76% at five and 22% at ten years. There was no significant relationship between survival and age (p = 0.37) or the pre- and post-operative centre-edge (p = 0.39) and acetabular angles (p = 0.85). Shelf acetabuloplasty is a reliable, safe procedure offering medium-term symptomatic relief for adults with acetabular dysplasia. The best results were achieved in patients with mild and moderate dysplasia of the hip with little arthritis.

A mobile-bearing total knee prosthesis compared with a fixed-bearing prosthesis. A multicentre single-blind randomised controlled trial.

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.

Ultrasonically driven tools.

Ultrasonically driven tools have been employed extensively in revision hip surgery during the last 2 years at the Nuffield Orthopaedic Centre. In combination with hand revision instruments, the removal of cement, in particular the removal of the distal cement plug, has been made safer. One significant complication that has occurred with this device is reported and advice on its prevention offered.

Diagnosis of infection by frozen section during revision arthroplasty.

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.