Aims. Unicompartmental knee arthroplasty (UKA) is the preferred treatment for anterior medial knee osteoarthritis (OA) owing to the rapid postoperative recovery. However, the risk factors for UKA failure remain controversial. Methods. The clinical data of Oxford mobile-bearing UKAs performed between 2011 and 2017 with a minimum follow-up of five years were retrospectively analyzed. Demographic, surgical, and follow-up data were collected. The Cox proportional hazards model was used to identify the risk factors that contribute to UKA failure. Kaplan-Meier survival was used to compare the effect of the prosthesis position on UKA survival. Results. A total of 407 patients who underwent UKA were included in the study. The mean age of patients was 61.8 years, and the mean follow-up period of the patients was 91.7 months. The mean Knee Society Score (KSS) preoperatively and at the last follow-up were 64.2 and 89.7, respectively (p = 0.001). Overall, 28 patients (6.9%) with UKA underwent revision due to prosthesis loosening (16 patients), dislocation (eight patients), and persistent pain (four patients). Cox proportional hazards model analysis identified malposition of the prostheses as a high-risk factor for UKA failure (p = 0.007). Kaplan-Meier analysis revealed that the five-year survival rate of the group with malposition was 85.1%, which was significantly lower than that of the group with normal position (96.2%; p < 0.001). Conclusion. UKA constitutes an effective method for treating anteromedial knee OA, with an excellent five-year survival rate. Aseptic loosening caused by prosthesis malposition was identified as the main cause of UKA failure. Surgeons should pay close attention to prevent the potential occurrence of this problem. Cite this article: Bone Jt Open 2023;4(12):914–922

Aims. Achievement of accurate microbiological diagnosis prior to revision is key to reducing the high rates of persistent infection after revision knee surgery. The effect of change in the microorganism between the first- and second-stage revision of total knee arthroplasty for periprosthetic joint infection (PJI) on the success of management is not clear. Methods. A two-centre retrospective cohort study was conducted to review the outcome of patients who have undergone two-stage revision for treatment of knee arthroplasty PJI, focusing specifically on isolated micro-organisms at both the first- and second-stage procedure. Patient demographics, medical, and orthopaedic history data, including postoperative outcomes and subsequent treatment, were obtained from the electronic records and medical notes. Results. The study cohort consisted of 84 patients, of whom 59.5% (n = 50) had successful eradication of their infection at a mean follow-up of 4.7 years. For the 34 patients who had recurrence of infection, 58.8% (n = 20) had a change in isolated organism, compared to 18% (n = 9) in the infection eradication group (p < 0.001). When adjusting for confound, there was no association when the growth on the second stage was the same as the first (odd ratio (OR) 2.50, 95% confidence interval (CI) 0.49 to 12.50; p = 0.269); however, when a different organism was identified at the second stage, this was independently associated with failure of treatment (OR 8.40, 95% CI 2.91 to 24.39; p < 0.001). There were no other significant differences between the two cohorts with regard to patient demographics or type of organisms isolated. Conclusion. Change in the identified microorganism between first- and second-stage revision for PJI was associated with failure of management. Identification of this change in the microorganism prior to commencement of the second stage may help target antibiotic management and could improve the success of surgery in these patients. Cite this article: Bone Jt Open 2023;4(9):720–727

Abstract. Introduction. The prevalence of recurrent infection following two-stage exchange arthroplasty following failure of a total knee arthroplasty (TKA) has been reported to be 10% to 25%. There is limited literature available on repeat two stage revisions for TKA infection with only small cohorts and variable success rates. Methodology. A retrospective cohort study investigating the outcome of two stage revision arthroplasty for treatment of TKA infection was conducted with the aim of identifying factors linked to recurrence of infection. A consecutive cohort of all microbiology intra-operative periprosthetic knee samples from a single revision arthroplasty centre between January 2010 and December 2016 was identified. The final cohort consisted of 658 samples taken during 64 patients undergoing two stage revision knee surgery for infection. Patient demographics, medical and orthopaedic history data including post-operative outcomes and subsequent treatment was obtained from the electronic records system and medical notes. Results. 65.6% of the cohort (N=42) had successful eradication of their infection. For the twenty-two patients that had failure of their two stage revision, twenty patients had samples available from further surgical intervention. Sixteen patients (80%) had different organisms isolated when they had repeat surgical samples taken when compared to their first stage samples. Overall, for subsequent treatments there was a success rate of 75% if the same organism was identified and 62.5% if there were new isolated organisms. Conclusion. These findings may have implications for the treatment strategies chosen for re-infection after two stage TKA revisions if new causative organisms are isolated

Previous studies of failure mechanisms leading to revision total knee replacement (TKR) performed between 1986 and 2000 determined that many failed early, with a disproportionate amount accounted for by infection and implant-associated factors including wear, loosening and instability. Since then, efforts have been made to improve implant performance and instruct surgeons in best practice. Recently our centre participated in a multi-centre evaluation of 844 revision TKRs from 2010 to 2011. The purpose was to report a detailed analysis of failure mechanisms over time and to see if failure modes have changed over the past 10 to 15 years. Aseptic loosening was the predominant mechanism of failure (31.2%), followed by instability (18.7%), infection (16.2%), polyethylene wear (10.0%), arthrofibrosis (6.9%) and malalignment (6.6%). The mean time to failure was 5.9 years (ten days to 31 years), 35.3% of all revisions occurred at less than two years, and 60.2% in the first five years. With improvements in implant and polyethylene manufacture, polyethylene wear is no longer a leading cause of failure. Early mechanisms of failure are primarily technical errors. In addition to improving implant longevity, industry and surgeons must work together to decrease these technical errors. All reports on failure of TKR contain patients with unexplained pain who not infrequently have unmet expectations. Surgeons must work to achieve realistic patient expectations pre-operatively, and therefore, improve patient satisfaction post-operatively. Cite this article: Bone Joint J 2014;96-B(11 Suppl A):101–4

Aims

Total knee arthroplasty (TKA) is a common and safe orthopaedic procedure. Zimmer Biomet's NexGen is the second most popular brand of implant used in the UK. The primary cause of revision after the first year is aseptic loosening. We present our experience of using this implant, with significant concerns around its performance with regards early aseptic loosening of the tibial component.

Aims. The number of revision total knee arthroplasties (TKA) that are performed is expected to increase. However, previous reports of the causes of failure after TKA are limited in that they report the causes at specific institutions, which are often dependent on referral patterns. Our aim was to report the most common indications for re-operations and revisions in a large series of posterior-stabilised TKAs undertaken at a single institution, excluding referrals from elsewhere, which may bias the causes of failure. Patients and Methods. A total of 5098 TKAs which were undertaken between 2000 and 2012 were included in the study. Re-operations, revisions with modular component exchange, and revisions with non-modular component replacement or removal were identified from the medical records. The mean follow-up was five years (two to 12). Results. The Kaplan-Meier ten-year survival without a re-operation, modular component revision and non-modular component revision was 95.7%, 99.3% and 95.3%, respectively. The most common indications for a re-operation were: post-operative stiffness (58%), delayed wound healing (21%), and patellar clunk (11%). The indications for isolated modular component revision were acute periprosthetic joint infection (PJI) (64%) and instability (36%). The most common indications for non-modular component revision were chronic PJI (52%), aseptic loosening (17%), periprosthetic fracture (10%), and instability (10%). Conclusion. Post-operative stiffness remains the most common indication for re-operation after TKA. Infection is the most common indication for modular and non-modular component revision. Aseptic loosening was not an uncommon cause of failure, however, it was much less common than in national registry and non-registry data. Focusing on posterior-stabilised TKAs initially performed at our institution allowed for an accurate assessment of the causes of failure in a contemporary specialty practice. Cite this article: Bone Joint J 2017;99-B:647–52

Introduction. The effect of using thicker liners in primary total knee arthroplasty (TKA) on functional outcomes and aseptic failure rates remains largely unknown. As such, we devised a multicenter study to assess both the clinical outcomes and survivorship of thick vs thin liners after primary TKA. Methods. A search of our institutional databases was performed for patients having undergone bilateral (simultaneous or staged) primary TKA with similar preoperative and surgical characteristics between both sides. Two cohorts were created: thick liners and thin liners. Outcomes collected were as follows: change in Knee Society Score (DKSS), change in range of motion, and aseptic revision. Ad hoc power analysis was performed for DKSS (α ¼ 0.05; power ¼ 80%). Differences between cohorts were assessed. Results. 195 TKAs were identified for each cohort. DKSS and change in range of motion in the thin vs thick cohorts were similar: 51.4 vs 51.6 (P ¼ .86) and 11.1 vs 10.0 (P ¼ .66), respectively. No difference in aseptic revision rates were observed between thin and thick cohorts: all cause (4.1%, 3.1%; P ¼ .59), aseptic loosening (0.5%, 0.5%; P ¼ 1.0), instability (0.5%, 0.5%; P ¼ 1.0), all-cause revision for stiffness (3.1%, 2.1%; P ¼ .52), manipulation under anesthesia (2.1%, 2.1%; P ¼ 1.0), and liner exchange (0.5%, 0%; P ¼ .32). Conclusion. The results of this study suggest that both rates of revision surgery and clinical outcomes are similar for TKAs performed with thick and thin liners. Preoperative factors are likely to play an important role in liner thickness selection, and emphasis should be placed on ensuring sound surgical technique

The relationship between post-operative bone density and subsequent failure of total knee replacement (TKR) is not known. This retrospective study aimed to determine the relationship between bone density and failure, both overall and according to failure mechanism. All 54 aseptic failures occurring in 50 patients from 7760 consecutive primary cemented TKRs between 1983 and 2004 were matched with non-failing TKRs, and 47 failures in 44 patients involved tibial failures with the matching characteristics of age (65.1 for failed and 69.8 for non-failed), gender (70.2% female), diagnosis (93.6% OA), date of operation, bilaterality, pre-operative alignment (0.4 and 0.3 respectively), and body mass index (30.2 and 30.0 respectively). In each case, the density of bone beneath the tibial component was assessed at each follow-up interval using standardised, calibrated radiographs. Failing knees were compared with controls both overall and, as a subgroup analysis, by failure mechanism. Knees were compared with controls using univariable linear regression. Significant and continuous elevation in tibial density was found in knees that eventually failed by medial collapse (p < 0.001) and progressive radiolucency (p < 0.001) compared with controls, particularly in the medial region of the tibia. Knees failing due to ligamentous instability demonstrated an initial decline in density (p = 0.0152) followed by a non-decreasing density over time (p = 0.034 for equivalence). Non-failing knees reported a decline in density similar to that reported previously using dual-energy x-ray absorptiometry (DEXA). Differences between failing and non-failing knees were observable as early as two months following surgery. This tool may be used to identify patients at risk of failure following TKR, but more validation work is needed. Cite this article: Bone Joint J 2014;96-B:1503–9

Total knee arthroplasty (TKA) is a cost effective and extremely successful operation. As longevity increases, the demand for primary TKA will continue to rise. The success and survivorship of TKAs are dependent on the demographics of the patient, surgical technique and implant-related factors. . Currently the risk of failure of a TKA requiring revision surgery ten years post-operatively is 5%. . The most common indications for revision include aseptic loosening (29.8%), infection (14.8%), and pain (9.5%). Revision surgery poses considerable clinical burdens on patients and financial burdens on healthcare systems. . We present a current concepts review on the epidemiology of failed TKAs using data from worldwide National Joint Registries. Cite this article: Bone Joint J 2016;98-B(1 Suppl A):105–12

We describe a cohort of patients with a high rate of mid-term failure following Kinemax Plus total knee replacement inserted between 1998 and 2001. This implant has been recorded as having a survival rate of 96% at ten years. However, in our series the survival rate was 75% at nine years. This was also significantly lower than that of subsequent consecutive series of PFC Sigma knee replacements performed by the same surgeon. No differences were found in the clinical and radiological parameters between the two groups. At revision the most striking finding was polyethylene wear. An independent analysis of the polyethylene components was therefore undertaken. Scanning electron microscopy revealed type 2 fusion defects in the ultra-high molecular weight polyethylene (UHMWPE), which indicated incomplete boundary fusion. Other abnormalities consistent with weak UHMWPE particle interface strength were present in both the explanted inserts and in unused inserts from the same period. We consider that these type 2 fusion defects are the cause of the early failure of the Kinemax implants. This may represent a manufacturing defect resulting in a form of programmed polyethylene failure

Background. Unicompartmental knee arthroplasty provides a good alternative to total knee arthroplasty in patients with isolated medial compartment osteoarthritis. There has been variable reporting in the literature as to whether age and sex affect the survival of unicompartmental knee arthroplasty. Study aims. The aims of this study were to determine whether age and sex were predictors of failure for the Oxford unicompartmental knee arthroplasty. Methods. Details of consecutive patients undergoing Oxford unicompartmental knee arthroplasty at our centre between January 2000 and December 2009 were collected prospectively. Failure of the implant was defined as conversion to total knee arthroplasty. Survival was determined using the Kaplan-Meier method. A Cox proportional hazard model was used to determine the affect of age and sex on survival of the prosthesis. Results. There were 494 Oxford unicompartmental knee arthroplasties implanted in 425 patients for isolated medial compartment osteoarthritis. Mean age was 62.8 yr (range 34.6-90.1 yr) and 53.4% were female. During a mean follow-up time of 3.0 yr (range 0.5-9.2 yr), twenty knees (4.0%) were revised to a total knee arthroplasty. Age had a statistically significant impact on survival (p=0.018), with increasing age associated with improved survival of the prosthesis. Sex was not demonstrated to be a statistically significant predictor of failure. Conclusions. Our findings demonstrate that decreasing age was a predictor of failure of the Oxford unicompartmental knee arthroplasty, but sex had no impact on failure of the prosthesis. It is therefore recommended that age should be taken into account when younger patients are being considered for Oxford unicompartmental knee arthroplasty. In addition, preoperatively younger patients should be counselled appropriately regarding the increased risk of revision surgery

Background. A number of studies have reported on the early failure of the Oxford unicompartmental knee arthroplasty. However, less evidence is available regarding the outcome following revision of failed unicompartmental knee prostheses to total knee arthroplasty. Study aims. The study aims were to determine the time to failure and mode of failure for the Oxford unicompartmental knee arthroplasty and to assess the short-term outcome following revision surgery. Methods. Details of consecutive patients undergoing revision of an Oxford unicompartmental knee arthroplasty to a total knee arthroplasty at our centre between January 2000 and December 2009 were collected prospectively. Data was collected on patient demographics, time to revision, and revision indication. Clinical, functional and radiological outcome following revision were assessed. Results. Of 494 Oxford unicompartmental knee arthroplasties implanted, 20 (4.0%) were revised to a total knee arthroplasty. Mean age at revision was 63.5 yr and 50% were male. Mean time to revision surgery from the index procedure was 3.2 yr (range 1.2-6.2 yr). The commonest reason for revision was aseptic loosening of the femoral (n=9) or tibial component (n=2). All patients were revised to a cemented total knee arthroplasty. Three patients required femoral and/or tibial augments. During follow-up (range 0.5-4.5 yr) there was one case of superficial wound infection. One patient underwent a further revision for instability 1.5 years following the initial revision procedure. Discussion. The present study demonstrates most failures of the Oxford unicompartmental knee arthroplasty are due to aseptic component loosening, occur within four years, and do not require femoral or tibial augmentation when revised. These findings are consistent with other published reports regarding the early failure of this prosthesis. The short-term outcome following revision surgery appears to be good, however longer follow-up periods are required to determine if these results continue

Metallosis is a rare cause of failure after total knee replacement and has only previously been reported when there has been abnormal metal-on-metal contact. We describe 14 patients (15 knees) whose total knee replacement required revision for a new type of early failure caused by extensive metallosis. A modification of a cementless rotating platform implant, which had previously had excellent long-term survival, had been used in each case. The change was in the form of a new porous-beaded surface on the femoral component to induce cementless fixation, which had been used successfully in the fixation of acetabular and tibial components. This modification appeared to have resulted in metallosis due to abrasive two-body wear. The component has subsequently been recalled and is no longer in use. The presentation, investigation, and findings at revision are described and a possible aetiology and its implications are discussed

Aims. The aim of this study was to determine if a three-month course of microorganism-directed oral antibiotics reduces the rate of failure due to further infection following two-stage revision for chronic prosthetic joint infection (PJI) of the hip and knee. Methods. A total of 185 patients undergoing a two-stage revision in seven different centres were prospectively enrolled. Of these patients, 93 were randomized to receive microorganism-directed oral antibiotics for three months following reimplantation; 88 were randomized to receive no antibiotics, and four were withdrawn before randomization. Of the 181 randomized patients, 28 were lost to follow-up, six died before two years follow-up, and five with culture negative infections were excluded. The remaining 142 patients were followed for a mean of 3.3 years (2.0 to 7.6) with failure due to a further infection as the primary endpoint. Patients who were treated with antibiotics were also assessed for their adherence to the medication regime and for side effects to antibiotics. Results. Nine of 72 patients (12.5%) who received antibiotics failed due to further infection compared with 20 of 70 patients (28.6%) who did not receive antibiotics (p = 0.012). Five patients (6.9%) in the treatment group experienced adverse effects related to the administered antibiotics severe enough to warrant discontinuation. Conclusion. This multicentre randomized controlled trial showed that a three-month course of microorganism-directed, oral antibiotics significantly reduced the rate of failure due to further infection following a two-stage revision of total hip or knee arthroplasty for chronic PJI. Cite this article: Bone Joint J 2020;102-B(6 Supple A):3–9

Purpose. Little information is available relating to patient demographics, reasons for failure and types of implants used at time of revision following failure of patellofemoral joint (PFJ) replacement. Methods and Results. Using data extracted from the NJR a series of 128 PFJ revisions in whom the index primary procedure was also recorded in the NJR were identified. This cohort therefore represents early failures of PFJ replacements revised over a 2 year period which were implanted after April 2003 and included revisions of 11 different brands of PFJ replacement from 6 different manufacturers. The median age at primary procedure was 59.0 (Range 21.1 to 83.2) of which 43 patients were <55 years old (31 males, 97 females). 19% of the revisions were performed in the first year after implantation, in the second year in 33 cases (26%), in the third year in 39 cases (31%) and between years 4 to 7 in 32 patients (25%). The commonest reasons for revision were pain (35%), aseptic loosening (18%), subluxation, dislocation or instability (11%), PE wear (7%) and component malalignment (6%). No reason for revision was stated in 30% and only 2 cases were revised for infection. Reason for revision differed according to year of failure but was consistent with respect to age at primary surgery. PFJ revision reason differed from those stated for revisions of primary UKR and TKR from the same period with pain being more prevalent and aseptic loosening and infection being less prevalent in the PFJ group. Single stage revision was performed in 124 cases and 118 underwent cemented revision. Conclusion. Limited data exists on the demographics and outcome for patellofemoral arthroplasty revision. This study is the first to identify reasons for failure in a large cohort and relate such to duration of primary component

Background. Dual compartment knee replacement has been introduced to allow sparing of the cruciate ligaments and lateral compartment and preserve some biomechanics of knee function. Aim. To study the early clinical and radiographic results of this new prosthesis. Method. Patients who underwent dual compartmental knee arthroplasty performed by 2 surgeons over a period of one year were studied prospectively. All subjects in the study had advanced symptomatic osteoarthritis of the medial and patellofemoral joints but had an intact ACL and preserved lateral compartment. All patients received the Journey Deuce Dual Compartmental Knee System (Smith & Nephew, Inc, Memphis, Tenn) with Oxinium femoral component and modular tibial component. Follow-up with clinical evaluation, radiographs and Oxford knee scores were performed at 6 weeks, 6 months, 1 year, 2 years. Results. Mean follow up was 18months (range 12-24months). There were 15 patients (6 males, 9 females) with a mean age of 53 years (range, 46-68 years). Twelve of the 15 patients had their patella resurfaced. The mean inpatient stay was 4.5 days (range 3-11 days). The mean time taken for surgery was 80 minutes (range 77-112 minutes). Six of the 15 patients had poor results following surgery. Five out of six patients with poor results had tibial base plate loosening. This was confirmed either on plain x-rays, bone scan or at the time of revision surgery. Patients with tibial base plate loosening typically presented with persistent pain, particularly of the metaphyseal region when weightbearing and an effusion. One revision was performed for patellofemoral pain and maltracking. In total, three patients have already been revised and three are awaiting revision surgery. Further procedures were required in 2 patients. Conclusion. The Deuce dual compartmental knee replacement in its current design results in an unacceptably high rate of failure due to tibial base plate loosening. Some of these patients had good results in the early postoperative period which then deteriorated. Considering the high rates of failure we do not recommend this replacement with its current tibial plate design

The aims of this retrospective study were to compare the mid-term outcomes following revision total knee replacement (TKR) in 76 patients (81 knees) < 55 years of age with those of a matched group of primary TKRs based on age, BMI, gender and comorbid conditions. We report the activity levels, functional scores, rates of revision and complications. Compared with patients undergoing primary TKR, those undergoing revision TKR had less improvement in the mean Knee Society function scores (8.14 (–55 to +60) vs 23.3 points (–40 to +80), p < 0.001), a similar improvement in UCLA activity level (p = 0.52), and similar minor complication rates (16% vs 13%, p = 0.83) at a mean follow-up of 4.6 years (2 to 13.4). Further revision surgery was more common among revised TKRs (17% vs 5%, p = 0.02), with deep infection and instability being the most common reasons for failure. As many as one-third of patients aged < 55 years in the revision group had a complication or failure requiring further surgery. Young patients undergoing revision TKR should be counselled that they can expect somewhat less improvement and a higher risk of complications than occur after primary TKR. Cite this article: Bone Joint J 2014; 96-B:1657–62

Antibiotic prophylaxis for joint replacement surgery is widely recommended and has been shown to reduce infection rates. Cephalosporins have commonly been used but are associated with development of Clostridium difficile associated diarrhoea (CDAD). The purpose of this study was to assess whether a change of protocol aimed at reducing CDAD, including a change of antibiotic prophylaxis would reduce rates of CDAD and other postoperative complications. We studied all 7989 patients in our trust that underwent hip or knee replacement from May 2002 to March 2009. These patients fell into two cohorts, firstly those who were prescribed cefuroxime as prophylaxis and secondly those prescribed gentamicin which was introduced following national concern regarding CDAD. Following the change of prophylaxis from cefuroxime 750mg three doses to gentamicin 4.5 mg/kg single dose the rate of CDAD reduced significantly (0.17% to 0%, p<0.03), however the rate of acute renal failure (0.29% to 0.6%, p=0.04) and pneumonia (0.71% to 1.38%, p<0.01) increased significantly. The rate of urinary tract infection (1.44% to 1.20%, p >0.05) and the overall return to theatre rate (1.86% to 2.30%, p=0.21) were not significantly changed. The spectrum of bacteria grown from infected joint replacements in the two cohorts was also analysed. The rate of deep MRSA infection was significantly less in the group given gentamicin. The frequency of other bacteria was also different between the cohorts, but not significantly so. We conclude that changing protocol including antibiotic prophylaxis in joint replacement patients can have the desired effect on a particular outcome namely CDAD but can also result in increased rates of other postoperative complications. It is also likely to result in a change in the bacterial spectrum of infected joint replacements

Aim

We aim to compare revision rates and functional outcome scores in between two contemporary total knee arthoplasty systems.

A total of 10474 unicompartmental knee arthroplasties was performed for medial osteoarthritis in Sweden between 1986 and 1995. We sought to establish whether the number of operations performed in an orthopaedic unit affected the incidence of revision. Three different implants were analysed: one with a high revision rate, known to have unfavourable mechanical and design properties; a prosthesis which is technically demanding with a known increased rate of revision; and the most commonly used unicompartmental device.

Most of the units performed relatively few unicompartmental knee arthroplasties per year and there was an association between the mean number carried out and the risk of later revision. The effect of the mean number of operations per year on the risk of revision varied. The technically demanding implant was most affected, that most commonly used less so, and the outcome of the unfavourable design was not influenced by the number of operations performed.

For unicompartmental arthroplasty, the long-term results are related to the number performed by the unit, probably expressing the standards of management in selecting the patients and performing the operation.