Aims. The aim of this study was to evaluate medium- to long-term outcomes and complications of the Stanmore Modular Individualised Lower Extremity System (SMILES) rotating hinge implant in revision total knee arthroplasty (rTKA) at a tertiary unit. It is hypothesized that this fully cemented construct leads to satisfactory clinical outcomes. Methods. A retrospective consecutive study of all patients who underwent a rTKA using the fully cemented SMILES rotating hinge prosthesis between 2005 to 2018. Outcome measures included aseptic loosening, reoperations, revision for any cause, complications, and survivorship. Patients and implant survivorship data were identified through both prospectively collected local hospital electronic databases and linked data from the National Joint Registry/NHS Personal Demographic Service. Kaplan-Meier survival analysis was used at ten years. Results. Overall, 69 consecutive patients (69 knees) were included with a median age of 78 years (interquartile range 69 to 84), and there were 46 females (66.7%). Indications were septic revisions in 26 (37.7%), and aseptic aetiology in the remining 43 (62.3%). The mean follow-up was 9.7 years (4 to 18), and the overall complication was rate was 7.24%, all with patellofemoral complications. Failure rate with ‘any cause revision’ was 5.8%. There was one case of aseptic loosening of the femoral component. At ten years, 17/69 patients (24.63%) had died, and implant survivorship was 92.2%. Conclusion. In our experience, the SMILES rotating hinge prosthesis achieves satisfactory long-term outcomes with ten-year implant survivorship of 92.2% and a patellofemoral complication rate of 7.24%. Cite this article: Bone Jt Open 2023;4(10):776–781

Aims. The aim of this study was to identify variables associated with time to revision, demographic details associated with revision indication, and type of prosthesis employed, and to describe the survival of hinge knee arthroplasty (HKA) when used for first-time knee revision surgery and factors that were associated with re-revision. Methods. Patient demographic details, BMI, American Society of Anesthesiologists (ASA) grade, indication for revision, surgical approach, surgeon grade, implant type (fixed and rotating), time of revision from primary implantation, and re-revision if undertaken were obtained from the National Joint Registry data for England, Wales, Northern Ireland, and the Isle of Man over an 18-year period (2003 to 2021). Results. There were 3,855 patient episodes analyzed with a median age of 73 years (interquartile range (IQR) 66 to 80), and the majority were female (n = 2,480, 64.3%). The median time to revision from primary knee arthroplasty was 1,219 days (IQR 579 to 2,422). Younger age (p < 0.001), decreasing ASA grade (p < 0.001), and indications for revision of sepsis (p < 0.001), unexplained pain (p < 0.001), non-polyethylene wear (p < 0.001), and malalignment (p < 0.001) were all associated with an earlier time to revision from primary implantation. The median follow-up was 4.56 years (range 0.00 to 17.52), during which there were 410 re-revisions. The overall unadjusted probability of re-revision for all revision HKAs at one, five, and ten years after surgery were 2.7% (95% confidence interval (CI) 2.2 to 3.3), 10.7% (95% CI 9.6 to 11.9), and 16.2% (95% CI 14.5 to 17.9), respectively. Male sex (p < 0.001), younger age (p < 0.001), revision for septic indications (p < 0.001) or implant fracture (p = 0.010), a fixed hinge (p < 0.001), or surgery performed by a non-consultant grade (p = 0.023) were independently associated with an increased risk of re-revision. Conclusion. There were several factors associated with time to first revision. The re-revision rate was 16.2% at ten years; however, the risk factors associated with an increased risk of re-revision could be used to counsel patients regarding their outcome. Cite this article: Bone Joint J 2023;105-B(1):47–55

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

We studied a series of Endo-Modell(r) rotating hinge knee replacements (RHKRs) to determine indications, implant survival and complication rates. Case notes were audited for a consecutive series of 129 implants performed between 08/12/2002 and 30/01/2009. Indication for use of RHKR was complex primary arthroplasty in 37.8% and revision in 62.2%. For primary arthroplasty with hinge prosthesis, commonest indications were: collateral ligament insufficiency (44.4%); advanced RA (13.9%); supracondylar fracture (5.6%). Indications for revision RHK arthroplasty were: aseptic loosening (40.4%); ligamentous or soft tissue failure (14.0%); periprosthetic fracture (7%); infection (51%). Infection was proven in 21% with 54% of patients requiring a one stage and 46% two stage revision. For revision cases, 74% of primary prostheses were cruciate retaining PFC (Depuy) and in 5%, the primary was itself an Endo-Modell(r) RHKR. Mean time from index to revision procedures was 6.7 years (range 1 year – 23 years). Complications were: deep infection (6.1%) and non-fatal PE (1%). None developed clinically detectable DVT. Transfusion was required in 29 cases (for such cases, an average 3 units was given). 30-day mortality was 1%. For the revision cases, the average length of hospital admission was 11 days. Mean duration of follow up was 45 months (with a minimum of 21 days and maximum of 92 months). During this time 2 RHKRs failed. A total of 7 patients died during the period from complications unrelated to their surgery. 31 cases were lost to follow up. We conclude that in this series of Endo-Modell(r) rotating hinge knee arthroplasties, results are comparable with similar revision procedures. There was a low rate of prosthesis failure, DVT and PE

Summary

We report a large study of 331 patients at two years post operation who were prospectively randomised to receive either a rotating platform or a fixed bearing knee replacement of an otherwise identical design.

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. In cases of severe periprosthetic joint infection (PJI) of the knee, salvage procedures such as knee arthrodesis (KA) or above-knee amputation (AKA) must be considered. As both treatments result in limitations in quality of life (QoL), we aimed to compare outcomes and factors influencing complication rates, mortality, and mobility. Methods. Patients with PJI of the knee and subsequent KA or AKA between June 2011 and May 2021 were included. Demographic data, comorbidities, and patient history were analyzed. Functional outcomes and QoL were prospectively assessed in both groups with additional treatment-specific scores after AKA. Outcomes, complications, and mortality were evaluated. Results. A total of 98 patients were included, 52 treated with arthrodesis and 47 with AKA. The mean number of revision surgeries between primary arthroplasty and arthrodesis or AKA was 7.85 (SD 5.39). Mean follow-up was 77.7 months (SD 30.9), with a minimum follow-up of two years. Complications requiring further revision surgery occurred in 11.5% of patients after arthrodesis and in 37.0% of AKA patients. Positive intraoperative tissue cultures obtained during AKA was significantly associated with the risk of further surgical revision. Two-year mortality rate of arthrodesis was significantly lower compared to AKA (3.8% vs 28.3%), with age as an independent risk factor in the AKA group. Functional outcomes and QoL were better after arthrodesis compared to AKA. Neuropathic pain was reported by 19 patients after AKA, and only 45.7% of patients were fitted or were intended to be fitted with a prosthesis. One-year infection-free survival after arthrodesis was 88.5%, compared to 78.5% after AKA. Conclusion. Above-knee amputation in PJI results in high complication and mortality rates and poorer functional outcome compared to arthrodesis. Mortality rates after AKA depend on patient age and mobility, with most patients not able to be fitted with a prosthesis. Therefore, arthrodesis should be preferred whenever possible if salvage procedures are indicated. Cite this article: Bone Joint J 2024;106-B(7):669–679

Abstract. Introduction. Isolated patellofemoral joint(PFJ) osteoarthritis affects approximately 10% of patients aged over 40 years and treatment remains controversial. Our aim was to evaluate long term functional and radiological outcomes following PFJ arthorplasty with the Femoro Patella Vialli (FPV) prosthesis as this evidence is lacking in literature. Methodology. A retrospective review of prospectively collected PROMS in patients undergoing Patellofemoral arthroplasty. Single centre trial. Between 2004 and 2008, 101 FPV patellofemoral arthroplasties were performed in 80 patients with isolated patellofemoral joint osteoarthritis. Data was collected as a part of routine follow-up for up to 6 years and additional long term data was collected at 16 years. Results. At 6 year follow up the mean OKS was 29 and by 16 year follow up it was 26 which was not a statistically significant drop. 22 patients (29 knees) had died, 32 (32%) had been revised, 25 to total knee replacement using primary arthroplasty components. Mean OKS in the revised group was 27 which was not a statistically significant difference when compared to the unrevised group. Mean time to revision was 4 years. The cumulative survival analysis of the FPV implant was 76% at 5 years, 64% at 10 years. Conclusion. Our findings suggest the FPV patellofemoral prosthesis provides good pain relief and clinical outcomes however, the survivorship for this particular implant maybe lower as compared to the available literature. Patient reported outcomes are maintained over the implant life and are no worse once revised implying a staged approach to arthroplasty is reasonable

Abstract. Introduction. Choosing a hinged implant in the revision knee arthroplasty (rTKA) setting is challenging and limited data on implant performance exists. We present the survivorship and reason for failure in rTKA performed at our institution using the LINK hinge prosthesis, predominantly the cemented modular Endo-Model prosthesis. Methodology. 260 consecutive revision knee cases performed between 2012 and 2020 were reviewed retrospectively. Mean follow up was 27 months (range 0 to 107). Survivorship was analysed in Stata using a Log Rank test to compare performance in patients stratified according to age (≥80 years old (76 cases), 70–79 years (104 cases) and ≤70 years (80 cases). Results. 53 patients died and 48/207 (23%) cases in 40 patients underwent re-revision. Reasons for re-revision were aseptic loosening (21), infection (12), instability (4), extensor failure (1), stiffness (1), fracture (1) and other (8). Loosening was seen in the femur (8), tibia (5), and both the femur and tibia (8). Sub-group analysis of patients according to age showed a significantly higher failure rate in younger patients (6 failures (8%) in patients ≥80, 27 failures (26%) in 70–79 and 15 (19%) in ≤70 (p = 0.02). Failure in patients ≤70 was predominantly due to aseptic loosening (8/15). Conclusion. Here we report a significantly higher rate of LINK hinge prostheses failure in patients <70 undergoing rTKA. Consent should consider the risk of re-revision in this patient group

Abstract. Introduction. Failing total knee replacement management has included isotope bone scan to identify infection or loosening. BASK guidance suggests bone scans have a poor positive predictive value and are not advised. We assessed isotope bone scanning as a negative predictor to exclude loosening or infection in failing total knee replacement. Methodology. Retrospective review of consecutive bone scans performed to investigate painful total knee replacements for a one-year period (June 2017 to June 2018). 166 bone scans performed. 33 excluded (no notes or scan for other reasons). Demographic information, age of prosthesis, clinic review date, serological markers, results of aspiration and subsequent intraoperative findings also recorded. Results. 133 patients, mean age 72.7, average age of prosthesis 6.8 years. 45% scans performed showed evidence of infection or loosening. Of those positive scans, 70% had aspiration and consideration for revision surgery. 73 patients had negative scans. 2 patients had subsequent aspiration and in 1 patient, S. Epidermidis isolated (1 patient had patellar revision and further samples clear of and other patient declined further surgery). Conclusion. Isotope bone scan had a 97.2% negative predictive value making it a very useful tool to evaluate the failing knee replacement and exclude significant loosening or infection

Aims. The mean age of patients undergoing total knee arthroplasty (TKA) has reduced with time. Younger patients have increased expectations following TKA. Aseptic loosening of the tibial component is the most common cause of failure of TKA in the UK. Interest in cementless TKA has re-emerged due to its encouraging results in the younger patient population. We review a large series of tantalum trabecular metal cementless implants in patients who are at the highest risk of revision surgery. Methods. A total of 454 consecutive patients who underwent cementless TKA between August 2004 and December 2021 were reviewed. The mean follow-up was ten years. Plain radiographs were analyzed for radiolucent lines. Patients who underwent revision TKA were recorded, and the cause for revision was determined. Data from the National Joint Registry for England, Wales, Northern Island, the Isle of Man and the States of Guernsey (NJR) were compared with our series. Results. No patients in our series had evidence of radiolucent lines on their latest radiological assessment. Only eight patients out of 454 required revision arthroplasty, and none of these revisions were indicated for aseptic loosening of the tibial baseplate. When compared to data from the NJR annual report, Kaplan-Meier estimates from our series (2.94 (95% confidence interval (CI) 1.24 to 5.87)) show a significant reduction in cumulative estimates of revision compared to all cemented (4.82 (95% CI 4.69 to 4.96)) or cementless TKA (5.65 (95% CI 5.23 to 6.10)). Our data (2.94 (95% CI 1.24 to 5.87)) also show lower cumulative revision rates compared to the most popular implant (PFC Sigma Cemented Knee implant fixation, 4.03 (95% CI 3.75 to 4.33)). The prosthesis time revision rate (PTIR) estimates for our series (2.07 (95% CI 0.95 to 3.83)) were lower than those of cemented cases (4.53 (95% CI 4.49 to 4.57)) from NJR. Conclusion. The NexGen trabecular (tantalum) cementless implant has lower revision rates in our series compared to all cemented implants and other types of cementless implants, and its use in younger patients should be encouraged. Cite this article: Bone Jt Open 2024;5(4):277–285

Aims. Medial unicompartmental knee arthroplasty (mUKA) is an advised treatment for anteromedial knee osteoarthritis. While long-term survival after mUKA is well described, reported incidences of short-term surgical complications vary and the effect of surgical usage on complications is less established. We aimed to describe the overall occurrence and treatment of surgical complications within 90 days of mUKA, as well as occurrence in high-usage centres compared to low-usage centres. Methods. mUKAs performed in eight fast-track centres from February 2010 to June 2018 were included from the Lundbeck Foundation Centre for Fast-track Hip and Knee Replacement Database. All readmissions within 90 days of surgery underwent chart review and readmissions related to the surgical wound or the prosthesis were recorded. Centres were categorized as high-usage centres when using mUKA in ≥ 20% of annual knee arthroplasties. The occurrence of complications between high- and low-usage centres were compared using Fisher’s exact test. Results. We included 3,757 mUKAs: 2,377 mUKAs from high-usage centres and 1,380 mUKAs from low-usage centres. Surgical complications within 90 days occurred in 69 cases (1.8%), 45 (1.9%) in high-usage centres and 24 (1.7%) in low-usage centres (odds ratio (OR) 1.1 (95% confidence interval (CI) 0.65 to 1.8)). The most frequent complications were periprosthetic joint infections (PJIs) (n = 18; 0.48%), wound-related issues (n = 14; 0.37%), and periprosthetic fractures (n = 13; 0.35%). Bearing dislocations (n = 7; 0.19%) occurred primarily in procedures from high-usage centres. In high-usage centres, seven periprosthetic fractures (0.29%) occurred compared to six (0.43%) in low-usage centres (OR 0.68 (95% CI 0.20 to 2.0)). In high-usage centres, nine PJIs (0.38%) occurred compared to nine (0.65%) in low-usage centres (OR 0.58 (95% CI 0.22 to 1.6)). Conclusion. Surgical complications are rare after fast-track mUKA surgery and with no difference in overall occurrence of surgical complications between high- and low-usage centres, although the risk of some specific surgical complications may favour high-usage centres. Cite this article: Bone Jt Open 2023;4(6):457–462

Aims. This systematic review and meta-analysis aimed to compare the influence of patellar resurfacing following cruciate-retaining (CR) and posterior-stabilized (PS) total knee arthroplasty (TKA) on the incidence of anterior knee pain, knee-specific patient-reported outcome measures, complication rates, and reoperation rates. Methods. A systematic review of MEDLINE, PubMed, and Google Scholar was performed to identify randomized controlled trials (RCTs) according to search criteria. Search terms used included: arthroplasty, replacement, knee (Mesh), TKA, prosthesis, patella, patellar resurfacing, and patellar retaining. RCTs that compared patellar resurfacing versus unresurfaced in primary TKA were included for further analysis. Studies were evaluated using the Scottish Intercollegiate Guidelines Network assessment tool for quality and minimization of bias. Data were synthesized and meta-analysis performed. Results. There were 4,135 TKAs (2,068 resurfaced and 2,027 unresurfaced) identified in 35 separate cohorts from 33 peer-reviewed studies. Anterior knee pain rates were significantly higher in unresurfaced knees overall (odds ratio (OR) 1.84; 95% confidence interval (CI) 1.20 to 2.83; p = 0.006) but more specifically associated with CR implants (OR 1.95; 95% CI 1.0 to 3.52; p = 0.030). There was a significantly better Knee Society function score (mean difference (MD) -1.98; 95% CI -1.1 to -2.84; p < 0.001) and Oxford Knee Score (MD -2.24; 95% CI -0.07 to -4.41; p = 0.040) for PS implants when patellar resurfacing was performed, but these differences did not exceed the minimal clinically important difference for these scores. There were no significant differences in complication rates or infection rates according to implant design. There was an overall significantly higher reoperation rate for unresurfaced TKA (OR 1.46 (95% CI 1.04 to 2.06); p = 0.030) but there was no difference between PS or CR TKA. Conclusion. Patellar resurfacing, when performed with CR implants, resulted in lower rates of anterior knee pain and, when used with a PS implant, yielded better knee-specific functional outcomes. Patellar resurfacing was associated with a lower risk of reoperation overall, but implant type did not influence this. Cite this article: Bone Joint J 2023;105-B(6):622–634

Aims. Endoprosthetic reconstruction with a distal femoral arthroplasty (DFA) can be used to treat distal femoral bone loss from oncological and non-oncological causes. This study reports the short-term implant survivorship, complications, and risk factors for patients who underwent DFA for non-neoplastic indications. Methods. We performed a retrospective review of 75 patients from a single institution who underwent DFA for non-neoplastic indications, including aseptic loosening or mechanical failure of a previous prosthesis (n = 25), periprosthetic joint infection (PJI) (n = 23), and native or periprosthetic distal femur fracture or nonunion (n = 27). Patients with less than 24 months’ follow-up were excluded. We collected patient demographic data, complications, and reoperations. Reoperation for implant failure was used to calculate implant survivorship. Results. Overall one- and five-year implant survivorship was 87% and 76%, respectively. By indication for DFA, mechanical failure had one- and five-year implant survivorship of 92% and 68%, PJI of 91% and 72%, and distal femur fracture/nonunion of 78% and 70% (p = 0.618). A total of 37 patients (49%) experienced complications and 27 patients (36%) required one or more reoperation. PJI (n = 16, 21%), aseptic loosening (n = 9, 12%), and wound complications (n = 8, 11%) were the most common complications. Component revision (n = 10, 13.3%) and single-stage exchange for PJI (n = 9, 12.0 %) were the most common reoperations. Only younger age was significantly associated with increased complications (mean 67 years (SD 9.1)) with complication vs 71 years (SD 9.9) without complication; p = 0.048). Conclusion. DFA is a viable option for distal femoral bone loss from a range of non-oncological causes, demonstrating acceptable short-term survivorship but with high overall complication rates. Cite this article: Bone Jt Open 2022;3(3):173–181

Abstract. Introduction. Isolated patellofemoral osteoarthritis accounts for 10% of knee osteoarthritis. Many of these will not require arthroplasty solutions, but for those who are sufficiently symptomatic, patellofemoral joint (PFJ) replacement has been shown to be an effective procedure. The National Joint Registry (NJR) has shown a higher revision rate for this operation, particularly in younger patients (males <55 years 13.3% failure at 5 years, females 9.6%). The aim of this study is to report on the medium-term outcome of the Avon patellofemoral joint arthroplasty in patients under 55 from a non-design centre. There is no other published case series on this young patient cohort. Methodology. 50 Avon PFJ replacements (Stryker, Kalamazoo USA) were undertaken in 46 patients under 55 years old (range 35 – 54, mean 48.8) between 2010 and 2022 for end-stage isolated PFJ arthritis shown on Xray and MRI scan. The outcome measure was all-cause revision rate. This was assessed by review of clinical notes, imaging and NJR data. Results. The mean follow up was 5.8 years (range 6 months to 12.9 years). Only one patient had a revision procedure (for progressive osteoarthritis) which was 3 years after the primary procedure. This patient has had no further surgery. The implant survival rate was 97.2% at 5 years and 97.2% at 10 years. Conclusion. This study shows that patellofemoral joint replacement with the Avon prosthesis can give a satisfactory revision rate in the medium term in patients under 55 if carefully selected

Abstract. Customised individually made implants(CIM) total knee arthroplasty(TKA) are custom-made to better fit patients native anatomy and aim to improve outcomes which can be variable with conventional off-the-shelf(OTS). A systematic review and meta-analysis was conducted searching the MEDLINE and Embase databases. Studies reporting on patient reported outcome measures, clinical or radiological outcomes were included. 23 studies satisfied the search criteria (case-control studies14, case series8, cross-sectional studies1). There were 2,856(CIM) and 1,877(OTS) implants. The overall revision-rate was higher in CIM 5.9%vs3.7%OTS [OR 1.46(95% CI 0.82–2.62)]. MUA was higher in the CIM group 2.2%vs.1.1%OTS [OR 2.95(95% CI 0.95–9.13)] and overall complications rate was also higher in the CIM group 5% vs. 4.5%OTS [OR 1.45(95% CI 0.53–3.96)]. LOS was significantly shorter in the CIM group 2.9 days vs. 3.5 days [MD −0.51(95% CI −0.82–0.20)]. Pooled analysis for KSS showed no difference between CIM and OTS groups(Knee=90.5 vs. 90.6 [MD-0.27,(95% CI −4.27–3.73)] and Function=86.1 vs. 90.6[MD 1.51 (95% CI −3.69–6.70)] component of the scores. There was no significant difference in post-operative ROM between CIM and OTS groups 117.3° vs. 115.0° [MD 0.02,(95% CI −1.70–1.74)]. CIM TKAs has theoretical benefits over OTS TKAs however in this review they were associated with higher complication, MUA and revision rates with no difference in outcome scores and no improvement in target alignment. The findings of this review does not support the use of CIM over OTS prosthesis in total knee arthroplasty

Aims. Our purpose was to describe an unusual series of 21 patients with fungal osteomyelitis after an anterior cruciate ligament reconstruction (ACL-R). Methods. We present a case-series of consecutive patients treated at our institution due to a severe fungal osteomyelitis after an arthroscopic ACL-R from November 2005 to March 2015. Patients were referred to our institution from different areas of our country. We evaluated the amount of bone resection required, type of final reconstructive procedure performed, and Musculoskeletal Tumor Society (MSTS) functional score. Results. A total of 21 consecutive patients were included in the study; 19 were male with median age of 28 years (IQR 25 to 32). All ACL-R were performed with hamstrings autografts with different fixation techniques. An oncological-type debridement was needed to control persistent infection symptoms. There were no recurrences of fungal infection after median of four surgical debridements (IQR 3 to 6). Five patients underwent an extensive curettage due to the presence of large cavitary lesions and were reconstructed with hemicylindrical intercalary allografts (HIAs), preserving the epiphysis. An open surgical debridement was performed resecting the affected epiphysis in 15 patients, with a median bone loss of 11 cm (IQR 11.5 to 15.6). From these 15 cases, eight patients were reconstructed with allograft prosthesis composites (APC); six with tumour-type prosthesis (TTP) and one required a femoral TTP in combination with a tibial APC. One underwent an above-the-knee amputation. The median MSTS functional score was 20 points at a median of seven years (IQR 5 to 9) of follow-up. Conclusion. This study suggests that mucormycosis infection after an ACL-R is a serious complication. Diagnosis is usually delayed until major bone destructive lesions are present. This may originate additional massive reconstructive surgeries with severe functional limitations for the patients. Level of evidence: IV. Cite this article: Bone Joint Open 2020;2(1):3–8

Abstract. Introduction. The aims of our systematic review were to assess the Nickel sensitising potential of total knee arthroplasty (TKA), explore the relationship between Nickel hypersensitivity and clinical outcomes, and evaluate the utility of skin patch testing pre- and/or post-operatively. Methodology. A literature search was performed through EMBASE, Medline and PubMed databases. Articles were screened independently by two investigators. Levels of Evidence were assessed using Oxford CEBM criteria and quality was assessed using MINORS and Cochrane risk-of-bias tools. Results. Twenty studies met the eligibility criteria, reporting on 1354 TKAs. Prevalence of Nickel hypersensitivity ranged from 0% to 87.5%. Only one study which compared prevalence of hypersensitivity in the same patient group before and after surgery noted newly positive patch test reactions in 4.1%. Three studies reported lower prevalence of hypersensitivity in post-operative patients compared to pre-operative patients. Seven studies suggested hypersensitivity might cause complications; six studies did not support any relationship. Seven studies recommended pre-operative patch testing in patients with history of metal allergy; nine studies concluded testing may be valuable post-operatively. Conclusions. Patients undergoing TKA do not seem to be at increased risk of developing Nickel hypersensitivity, and there is conflicting evidence that patients with established hypersensitivity are more likely to experience adverse clinical outcomes. The evidence suggests performing patch testing pre-operatively in patients with history of metal allergy to aid selection of the most appropriate prosthesis, and post-operatively once common causes of implant failure have been excluded, since implant removal or revision with hypoallergenic implants may alleviate symptoms

Abstract. Introduction. Cementless total knee arthroplasty (TKA) offers a number of conceptual benefits including osteointegration, bone preservation and reduced aseptic loosening from third body wear. Evidence of equivalence to cemented fixation exists, but the cam-post interaction of posterior-stabilised (PS)-TKA on implant osteointegration remains uncertain. This study aims to assess the survivorship of a single prosthesis PS-TKA. Methodology. All patients undergoing a PS-TKA using the Triathlon Total Knee System (Stryker Orthopaedics, USA) between 01/01/2010 and 08/04/2019, with exposure to at least 2 years’ risk of revision were identified from the hospital database. Results. 1001 TKAs were identified; 734 cementless and 267 cemented. The cementless group more frequently were male, younger, of higher BMI; and had larger components used (p<0.01). Mean exposure to risk of revision was longer in the cementless group (69.5 vs 57 months, p<0.05). Return to theatre rates were similar (4.6% vs 4.8% p = 0.88), a greater proportion in the cementless group underwent revision (2.9% vs 1.1% p=0.11). Multivariate analysis was only possible for reoperations, increased with cemented fixation (OR 2.34 CI 1.01-5.43) and decreased with age (OR 0.96 CI 0.92-1.00). Conclusion. Both cementless and cemented Triathlon PS-TKA demonstrate excellent survivorship, with revision rates of 2.9% and 1.1% at a mean of 5.25 years. This difference was not statistically significant, and variations in baseline characteristics may have influenced it. Further study is planned to assess radiographs of these patients for evidence of osteointegration, and we advocate further study with greater patient numbers

Aim. There has been a significant reduction in unicompartmental knee arthroplasty (UKA) procedures recorded in Australia. This follows several national joint registry studies documenting high UKA revision rates when compared to total knee arthroplasty (TKA). With the recent introduction of robotically assisted UKA procedures, it is hoped that outcomes improve. This study examines the cumulative revision rate of UKA procedures implanted with a newly introduced robotic system and compares the results to one of the best performing non-robotically assisted UKA prostheses, as well as all other non-robotically assisted UKA procedures. Methods. Data from the Australian Orthopaedic Association National Joint Arthroplasty Registry (AOANJRR) for all UKA procedures performed for osteoarthritis (OA) between 2015 and 2018 were analyzed. Procedures using the Restoris MCK UKA prosthesis implanted using the Mako Robotic-Arm Assisted System were compared to non-robotically assisted Zimmer Unicompartmental High Flex Knee System (ZUK) UKA, a commonly used UKA with previously reported good outcomes and to all other non-robotically assisted UKA procedures using Cox proportional hazard ratios (HRs) and Kaplan-Meier estimates of survivorship. Results. There was no difference in the rate of revision when the Mako-assisted Restoris UKA was compared to the ZUK UKA (zero to nine months: HR 1.14 (95% CI 0.71 to 1.83; p = 0.596) vs nine months and over: HR 0.66 (95% CI 0.42 to 1.02; p = 0.058)). The Mako-assisted Restoris had a significantly lower overall revision rate compared to the other types of non-robotically assisted procedures (HR 0.58 (95% confidence interval (CI) 0.42 to 0.79); p < 0.001) at three years. Revision for aseptic loosening was lower for the Mako-assisted Restoris compared to all other non-robotically assisted UKA (entire period: HR 0.34 (95% CI 0.17 to 0.65); p = 0.001), but not the ZUK prosthesis. However, revision for infection was significantly higher for the Mako-assisted Restoris compared to the two comparator groups (ZUK: entire period: HR 2.91 (95% CI 1.22 to 6.98; p = 0.016); other non-robotically assisted UKA: zero to three months: HR 5.57 (95% CI 2.17 to 14.31; p < 0.001)). Conclusion. This study reports comparable short-term survivorship for the Mako robotically assisted UKA compared to the ZUK UKA and improved survivorship compared to all other non-robotic UKA. These results justify the continued use and investigation of this procedure. However, the higher rate of early revision for infection for robotically assisted UKA requires further investigation. Cite this article: Bone Joint J 2020;102-B(3):319–328