Aims. Dislocation remains a leading cause of failure following revision total hip arthroplasty (THA). While dual-mobility (DM) bearings have been shown to mitigate this risk, options are limited when retaining or implanting an uncemented shell without modular DM options. In these circumstances, a monoblock DM cup, designed for cementing, can be cemented into an uncemented acetabular shell. The goal of this study was to describe the implant survival, complications, and radiological outcomes of this construct. Methods. We identified 64 patients (65 hips) who had a single-design cemented DM cup cemented into an uncemented acetabular shell during revision THA between 2018 and 2020 at our institution. Cups were cemented into either uncemented cups designed for liner cementing (n = 48; 74%) or retained (n = 17; 26%) acetabular components. Median outer head diameter was 42 mm. Mean age was 69 years (SD 11), mean BMI was 32 kg/m. 2. (SD 8), and 52% (n = 34) were female. Survival was assessed using Kaplan-Meier methods. Mean follow-up was two years (SD 0.97). Results. There were nine cemented DM cup revisions: three for periprosthetic joint infection, three for acetabular aseptic loosening from bone, two for dislocation, and one for a broken cup-cage construct. The two-year survivals free of aseptic DM revision and dislocation were both 92%. There were five postoperative dislocations, all in patients with prior dislocation or abductor deficiency. On radiological review, the DM cup remained well-fixed at the cemented interface in all but one case. Conclusion. While dislocation was not eliminated in this series of complex revision THAs, this technique allowed for maximization of femoral head diameter and optimization of effective acetabular component position during cementing. Of note, there was only one failure at the cemented interface. Cite this article: Bone Joint J 2024;106-B(4):352–358

Recent publications have drawn attention to the fact that some brands of joint replacement may contain variants which perform significantly worse (or better) than their ‘siblings’. As a result, the National Joint Registry has performed much more detailed analysis on the larger families of knee arthroplasties in order to identify exactly where these differences may be present and may hitherto have remained hidden. The analysis of the Nexgen knee arthroplasty brand identified that some posterior-stabilized combinations have particularly high revision rates for aseptic loosening of the tibia, and consequently a medical device recall has been issued for the Nexgen ‘option’ tibial component which was implicated. More elaborate signal detection is required in order to identify such variation in results in a routine fashion if patients are to be protected from such variation in outcomes between closely related implant types. Cite this article: Bone Joint J 2023;105-B(3):221–226

Aims. The Birmingham Hip Resurfacing (BHR) was introduced in 1997 to address the needs of young active patients using a historically proven large-diameter metal-on-metal (MoM) bearing. A single designer surgeon’s consecutive series of 130 patients (144 hips) was previously reported at five and ten years, reporting three and ten failures, respectively. The aim of this study was to extend the follow-up of this original cohort at 25 years. Methods. The study extends the reporting on the first consecutive 144 resurfacing procedures in 130 patients for all indications. All operations were undertaken between August 1997 and May 1998. The mean age at operation was 52.1 years (SD 9.93; 17 to 76), and included 37 female patients (28.5%). Failure was defined as revision of either component for any reason. Kaplan-Meier survival analysis was performed. Routine follow-up with serum metal ion levels, radiographs, and Oxford Hip Scores (OHSs) was undertaken. Results. Overall implant survival was 83.50% (95% confidence interval (CI) 0.79 to 0.90) at 25 years, and the number at risk was 79. Survival in male patients at 25 years was 89.5% (95% CI 0.83 to 0.96) compared to 66.9% for female patients (95% CI 0.51 to 0.83). Ten additional failures occurred in the period of ten to 25 years. These involved an adverse reaction to metal debris in four patients, a periprosthetic femoral neck fracture affecting five patients, and aseptic loosening in one patient. The median chromium levels were 49.50 nmol/l (interquartile range (IQR) 34 to 70), and the median cobalt serum levels were 42 nmol/l (IQR 24.50 to 71.25). The median OHS at last follow-up was 35 (IQR 10 to 48). During the 25-year study period, 29 patients died. Patient survival at 25 years was 75.10% (95% CI 0.67 to 0.83). Conclusion. This study demonstrates that MoM hip resurfacing using the BHR provides a durable alternative to total hip arthroplasty (THA), particularly in younger male patients with osteoarthritis wishing to maintain a high level of function. These results compare favourably to the best results for THAs. Cite this article: Bone Joint J 2024;106-B(6):540–547

Aims. In patients with a failed radial head arthroplasty (RHA), simple removal of the implant is an option. However, there is little information in the literature about the outcome of this procedure. The aim of this study was to review the mid-term clinical and radiological results, and the rate of complications and removal of the implant, in patients whose initial RHA was undertaken acutely for trauma involving the elbow. Methods. A total of 11 patients in whom removal of a RHA without reimplantation was undertaken as a revision procedure were reviewed at a mean follow-up of 8.4 years (6 to 11). The range of motion (ROM) and stability of the elbow were recorded. Pain was assessed using a visual analogue scale (VAS). The functional outcome was assessed using the Mayo Elbow Performance Score (MEPS), the Oxford Elbow Score (OES), and the Disabilities of the Arm, Shoulder and Hand questionnaire (DASH). Radiological examination included the assessment of heterotopic ossification (HO), implant loosening, capitellar erosion, overlengthening, and osteoarthritis. Complications and the rate of further surgery were also recorded. Results. The indications for removal of the implant were stiffness in five patients, aseptic loosening in five, and pain attributed to the RHA in three. The mean time interval between RHA for trauma to removal was ten months (7 to 21). Preoperatively, three patients had overlengthening of the implant, three had capitellar erosion, six had HO, and four had radiological evidence of loosening. At the final follow-up, the mean the flexion-extension arc improved significantly by 38.2° (95% CI 20 to 59; p = 0.002) and the mean arc of prono-supination improved significantly by 20° (95% CI 0 to 72.5; p = 0.035). The mean pain VAS score improved significantly by 3.5 (95% CI 2 to 5.5; p = 0.004). The mean MEPS improved significantly by 27.5 (95% CI 17.5 to 42.5; p = 0.002). The mean OES improved significantly by 9 (95% CI 2.5 to 14; p = 0.012), and the mean DASH score improved significantly by 23.5 (95% CI 7.5 to 31.6; p = 0.012). Ten patients (91%) had HO and osteoarthritis. Two patients underwent further surgery due to stiffness and pain, respectively. Conclusion. Simple removal of the implant at revision surgery following a failed RHA introduced following trauma provides satisfactory mid-term results with an acceptable risk of complications. Osteoarthritis, instability, and radioulnar impingement were not problems in this series. Cite this article: Bone Joint J 2024;106-B(11):1327–1332

Aims. The aim of this study was to determine whether obesity had a detrimental effect on the long-term performance and survival of medial unicompartmental knee arthroplasties (UKAs). Methods. This study reviewed prospectively collected functional outcome scores and revision rates of all medial UKA patients with recorded BMI performed in Christchurch, New Zealand, from January 2011 to September 2021. Patient-reported outcome measures (PROMs) were the primary outcome of this study, with all-cause revision rate analyzed as a secondary outcome. PROMs were taken preoperatively, at six months, one year, five years, and ten years postoperatively. There were 873 patients who had functional scores recorded at five years and 164 patients had scores recorded at ten years. Further sub-group analysis was performed based on the patient’s BMI. Revision data were available through the New Zealand Joint Registry for 2,323 UKAs performed during this time period. Results. Obese patients (BMI > 30 kg/m. 2. ) were 3.1 years younger than non-obese patients (BMI < 30 kg/m. 2. ) at the time of surgery (mean age of obese patients 65.5 years (SD 9.7) and mean age of non-obese patients 68.6 years (SD 10.1)). Preoperatively, obese patients tended to have significantly lower functional scores than non-obese patients, which continued at five and ten years postoperatively. At these timepoints, obese patients had significantly lower scores for most PROMs measured compared to non-obese patients. However, there was no significant difference in the improvement of any of these scores after surgery between obese and non-obese patients. There was no significant difference in revision rates between obese and non-obese patients at any time. All-cause revision rate for obese patients was 0.73 per 100 observed component years compared to 0.67 in non-obese patients at ten years. There was also no significant difference in the aseptic loosening rate between groups. Conclusion. Our study supports the use of UKAs in obese patients, with similar benefit and survival compared to non-obese patients at ten years

Aims. Despite multiple trials and case series on hip hemiarthroplasty designs, guidance is still lacking on which implant to use. One particularly deficient area is long-term outcomes. We present over 1,000 consecutive cemented Thompson’s hemiarthroplasties over a ten-year period, recording all accessible patient and implant outcomes. Methods. Patient identifiers for a consecutive cohort treated between 1 January 2003 and 31 December 2011 were linked to radiographs, surgical notes, clinic letters, and mortality data from a national dataset. This allowed charting of their postoperative course, complications, readmissions, returns to theatre, revisions, and deaths. We also identified all postoperative attendances at the Emergency and Outpatient Departments, and recorded any subsequent skeletal injuries. Results. In total, 1,312 Thompson’s hemiarthroplasties were analyzed (mean age at surgery 82.8 years); 125 complications were recorded, necessitating 82 returns to theatre. These included 14 patients undergoing aspiration or manipulation under anaesthesia, 68 reoperations (5.2%) for debridement and implant retention (n = 12), haematoma evacuation (n = 2), open reduction for dislocation (n = 1), fixation of periprosthetic fracture (n = 5), and 48 revised stems (3.7%), for infection (n = 13), dislocation (n = 12), aseptic loosening (n = 9), persistent pain (n = 6), periprosthetic fracture (n = 4), acetabular erosion (n = 3), and metastatic bone disease (n = 1). Their status at ten years is summarized as follows: 1,180 (89.9%) dead without revision, 34 (2.6%) dead having had revision, 84 (6.6%) alive with the stem unrevised, and 14 (1.1%) alive having had revision. Cumulative implant survivorship was 90.3% at ten years; patient survivorship was 7.4%. Conclusion. The Thompson’s stem demonstrates very low rates of complications requiring reoperation and revision, up to ten years after the index procedure. Fewer than one in ten patients live for ten years after fracture. This study supports the use of a cemented Thompson’s implant as a cost-effective option for frail hip fracture patients. Cite this article: Bone Jt Open 2022;3(9):710–715

Aims. Although the Fitmore Hip Stem has been on the market for almost 15 years, it is still not well documented in randomized controlled trials. This study compares the Fitmore stem with the CementLeSs (CLS) in several different clinical and radiological aspects. The hypothesis is that there will be no difference in outcome between stems. Methods. In total, 44 patients with bilateral hip osteoarthritis were recruited from the outpatient clinic at a single tertiary orthopaedic centre. The patients were operated with bilateral one-stage total hip arthroplasty. The most painful hip was randomized to either Fitmore or CLS femoral component; the second hip was operated with the femoral component not used on the first side. Patients were evaluated at three and six months and at one, two, and five years postoperatively with patient-reported outcome measures, radiostereometric analysis, dual-energy X-ray absorptiometry, and conventional radiography. A total of 39 patients attended the follow-up visit at two years (primary outcome) and 35 patients at five years. The primary outcome was which hip the patient considered to have the best function at two years. Results. At two and five years, more patients considered the hip with the CLS femoral component as superior but without a statistically significant difference. There were no differences in clinical outcome, magnitude of femoral component migration, or change of bone mineral density at five years. At three months, the Fitmore femoral component had subsided a median -0.71 mm (interquartile range (IQR) -1.67 to -0.20) and the CLS femoral component -0.70 mm (IQR -1.53 to -0.17; p = 0.742). In both groups the femoral head centre had migrated posteriorly (Fitmore -0.17 mm (IQR -0.98 to -0.04) and CLS -0.23 mm (IQR -0.87 to 0.07; p = 0.936)). After three months neither of the femoral components showed much further migration. During the first postoperative year, one Fitmore femoral component was revised due to aseptic loosening. Conclusion. Up to five years, we found no statistically significant difference in outcomes between the Fitmore and the CLS femoral components. The slightly worse outcomes, including one revised hip because of loosening, speaks against the hypothesis that the Fitmore femoral component should be advantageous compared to the CLS if more patients had been recruited to this study. Cite this article: Bone Jt Open 2023;4(5):306–314

Aims. Unicompartmental knee arthroplasty (UKA) has a higher risk of revision than total knee arthroplasty (TKA), particularly for younger patients. The outcome of knee arthroplasty is typically defined as implant survival or revision incidence after a defined number of years. This can be difficult for patients to conceptualize. We aimed to calculate the ‘lifetime risk’ of revision for UKA as a more meaningful estimate of risk projection over a patient’s remaining lifetime, and to compare this to TKA. Methods. Incidence of revision and mortality for all primary UKAs performed from 1999 to 2019 (n = 13,481) was obtained from the New Zealand Joint Registry (NZJR). Lifetime risk of revision was calculated for patients and stratified by age, sex, and American Society of Anesthesiologists (ASA) grade. Results. The lifetime risk of revision was highest in the youngest age group (46 to 50 years; 40.4%) and decreased sequentially to the oldest (86 to 90 years; 3.7%). Across all age groups, lifetime risk of revision was higher for females (ranging from 4.3% to 43.4% vs males 2.9% to 37.4%) and patients with a higher ASA grade (ASA 3 to 4, ranging from 8.8% to 41.2% vs ASA 1 1.8% to 29.8%). The lifetime risk of revision for UKA was double that of TKA across all age groups (ranging from 3.7% to 40.4% for UKA, and 1.6% to 22.4% for TKA). The higher risk of revision in younger patients was associated with aseptic loosening in both sexes and pain in females. Periprosthetic joint infection (PJI) accounted for 4% of all UKA revisions, in contrast with 27% for TKA; the risk of PJI was higher for males than females for both procedures. Conclusion. Lifetime risk of revision may be a more meaningful measure of arthroplasty outcomes than implant survival at defined time periods. This study highlights the higher lifetime risk of UKA revision for younger patients, females, and those with a higher ASA grade, which can aid with patient counselling prior to UKA. Cite this article: Bone Joint J 2022;104-B(6):672–679

Aims. Highly polished stems with force-closed design have shown satisfactory clinical results despite being related to relatively high early migration. It has been suggested that the minimal thickness of cement mantles surrounding the femoral stem should be 2 mm to 4 mm to avoid aseptic loosening. The line-to-line cementing technique of the femoral stem, designed to achieve stem press-fit, challenges this opinion. We compared the migration of a highly polished stem with force-closed design by standard and line-to-line cementing to investigate whether differences in early migration of the stems occur in a clinical study. Methods. In this single-blind, randomized controlled, clinical radiostereometric analysis (RSA) study, the migration pattern of the cemented Corail hip stem was compared between line-to-line and standard cementing in 48 arthroplasties. The primary outcome measure was femoral stem migration in terms of rotation and translation around and along with the X-, Y-, and Z- axes measured using model-based RSA at three, 12, and 24 months. A linear mixed-effects model was used for statistical analysis. Results. Results from mixed model analyses revealed a lower mean retroversion for line-to-line (0.72° (95% confidence interval (CI) 0.38° to 1.07°; p < 0.001), but no significant differences in subsidence between the techniques (-0.15 mm (95% CI -0.53 to 0.227; p = 0.429) at 24 months. Radiolucent lines measuring < 2 mm wide were found in three and five arthroplasties cemented by the standard and line-to-line method, respectively. Conclusion. The cemented Corail stem with a force-closed design seems to settle earlier and better with the line-to-line cementing method, although for subsidence the difference was not significant. However, the lower rate of migration into retroversion may reduce the wear and cement deformation, contributing to good long-term fixation and implant survival. Cite this article: Bone Joint J 2022;104-B(1):19–26

Aims. Histology is an established tool in diagnosing periprosthetic joint infections (PJIs). Different thresholds, using various infection definitions and histopathological criteria, have been described. This study determined the performance of different thresholds of polymorphonuclear neutrophils (≥ 5 PMN/HPF, ≥ 10 PMN/HPF, ≥ 23 PMN/10 HPF) , when using the European Bone and Joint Infection Society (EBJIS), Infectious Diseases Society of America (IDSA), and the International Consensus Meeting (ICM) 2018 criteria for PJI. Methods. A total of 119 patients undergoing revision total hip (rTHA) or knee arthroplasty (rTKA) were included. Permanent histology sections of periprosthetic tissue were evaluated under high power (400× magnification) and neutrophils were counted per HPF. The mean neutrophil count in ten HPFs was calculated (PMN/HPF). Based on receiver operating characteristic (ROC) curve analysis and the z-test, thresholds were compared. Results. Using the EBJIS criteria, a cut-off of ≥ five PMN/HPF showed a sensitivity of 93% (95% confidence interval (CI) 81 to 98) and specificity of 84% (95% CI 74 to 91). The optimal threshold when applying the IDSA and ICM criteria was ≥ ten PMN/HPF with sensitivities of 94% (95% CI 79 to 99) and 90% (95% CI 76 to 97), and specificities of 86% (95% CI 77 to 92) and 92% (95% CI 84 to 97), respectively. In rTKA, a better performance of histopathological analysis was observed in comparison with rTHA when using the IDSA criteria (p < 0.001). Conclusion. With high accuracy, histopathological analysis can be supported as a confirmatory criterion in diagnosing periprosthetic joint infections. A threshold of ≥ five PMN/HPF can be recommended to distinguish between septic and aseptic loosening, with an increased possibility of detecting more infections caused by low-virulence organisms. However, neutrophil counts between one and five should be considered suggestive of infection and interpreted carefully in conjunction with other diagnostic test methods. Cite this article: Bone Joint Res 2021;10(8):536–547

We reviewed the records and radiographs of 387 cemented revisions of aseptic loose sockets after total hip replacement at a mean follow-up of 5.5 years. The clinical results were satisfactory, but at the last radiological assessment 38 sockets (9.8%) had a continuous zone of demarcation greater than 1 mm thick and another 35 (9%) showed migration. Poor acetabular bone stock had a profound influence on the outcome of revision surgery, but the results of cemented revision were comparable to those reported for cementless revision at similar mean follow-up.

Aims

Return to sport following undergoing total (TKA) and unicompartmental knee arthroplasty (UKA) has been researched with meta-analyses and systematic reviews of varying quality. The aim of this study is to create an umbrella review to consolidate the data into consensus guidelines for returning to sports following TKA and UKA.

Aims. Endoprosthetic reconstruction following distal femur tumour resection has been widely advocated. In this paper, we present the design of an uncemented endoprosthesis system featuring a short, curved stem, with the goal of enhancing long-term survivorship and functional outcomes. Methods. This study involved patients who underwent implantation of an uncemented distal femoral endoprosthesis with a short and curved stem between 2014 and 2019. Functional outcomes were assessed using the 1993 version of the Musculoskeletal Tumour Society (MSTS-93) score. Additionally, we quantified five types of complications and assessed osseointegration radiologically. The survivorship of the endoprosthesis was evaluated according to two endpoints. A total of 134 patients with a median age of 26 years (IQR 16 to 41) were included in our study. The median follow-up time was 61 months (IQR 56 to 76), and the median functional MSTS-93 was 83% (IQR 73 to 91) postoperatively. Results. Overall, 21 patients (16%) encountered complications, and the rate of aseptic loosening was 7% (9/134). The survival rate up to 8.5 years was 93% for aseptic loosening as the endpoint, and 88% for any reason as the endpoint, retrospectively. Conclusion. The use of an uncemented distal femoral endoprosthesis with a short, curved stem demonstrated a low incidence of aseptic loosening and achieved long-term survivorship of up to nine years. Meanwhile, aseptic loosening typically occurs in the early stage postoperatively. Cite this article: Bone Joint J 2024;106-B(9):1000–1007

Aims. The aim of this study was to explore the relationship between reason for revision total hip arthroplasty (rTHA) and outcomes in terms of patient-reported outcome measures (PROMs). Methods. We reviewed a prospective cohort of 647 patients undergoing full or partial rTHA at a single high-volume centre with a minimum of two years’ follow-up. The reasons for revision were classified as: infection; aseptic loosening; dislocation; structural failure; and painful THA for other reasons. PROMs (modified Oxford Hip Score (mOHS), EuroQol five-dimension three-level health questionnaire (EQ-5D-3L) score, and visual analogue scales for pain during rest and activity), complication rates, and failure rates were compared among the groups. Results. The indication for revision influenced PROMs improvement over time. This finding mainly reflected preoperative differences between the groups, but diminished between the first and second postoperative years. Preoperatively, patients revised due to infection and aseptic loosening had a lower mOHS than patients with other indications for revision. Pain scores at baseline were highest in patients being revised for dislocation. Infection and aseptic loosening groups showed marked changes over time in both mOHS and EQ-5D-3L. Overall complications and re-revision rates were 35.4% and 9.7% respectively, with no differences between the groups (p = 0.351 and p = 0.470, respectively). Conclusion. Good outcomes were generally obtained regardless of the reason for revision, with patients having the poorest preoperative scores exhibiting the greatest improvement in PROMs. Furthermore, overall complication and reoperation rates were in line with previous reports and did not differ between different indications for rTHA. Cite this article: Bone Joint J 2022;104-B(7):859–866

Aims. This study aimed to investigate the optimal sagittal positioning of the uncemented femoral component in total knee arthroplasty to minimize the risk of aseptic loosening and periprosthetic fracture. Methods. Ten different sagittal placements of the femoral component, ranging from -5 mm (causing anterior notch) to +4 mm (causing anterior gap), were analyzed using finite element analysis. Both gait and squat loading conditions were simulated, and Von Mises stress and interface micromotion were evaluated to assess fracture and loosening risk. Results. During gait, varied sagittal positioning did not lead to excessive Von Mises stress or micromotion. However, under squat conditions, posterior positioning (-4 and -5 mm) resulted in stress exceeding 150 MPa at the femoral notch, indicating potential fracture risk. Conversely, +1 mm and 0 mm sagittal positions demonstrated minimal interface micromotion. Conclusion. Slightly anterior sagittal positioning (+1 mm) or neutral positioning (0 mm) effectively reduced stress concentration at the femoral notch and minimized interface micromotion. Thus, these positions are deemed suitable to decrease the risk of aseptic loosening and periprosthetic femoral fracture

Aims. The aim of this study was to evaluate the survival of a collarless, straight, hydroxyapatite-coated femoral stem in total hip arthroplasty (THA) at a minimum follow-up of 20 years. Methods. We reviewed the results of 165 THAs using the Omnifit HA system in 138 patients, performed between August 1993 and December 1999. The mean age of the patients at the time of surgery was 46 years (20 to 77). Avascular necrosis was the most common indication for THA, followed by ankylosing spondylitis and primary osteoarthritis. The mean follow-up was 22 years (20 to 31). At 20 and 25 years, 113 THAs in 91 patients and 63 THAs in 55 patients were available for review, respectively, while others died or were lost to follow-up. Kaplan-Meier analysis was performed to evaluate the survival of the stem. Radiographs were reviewed regularly, and the stability of the stem was evaluated using the Engh classification. Results. A total of seven stems (4.2%) were revised during the study period: one for aseptic loosening, three for periprosthetic fracture, two for infection, and one for recurrent dislocation. At 20 years, survival with revision of the stem for any indication and for aseptic loosening as the endpoint was 96.0% (95% confidence interval (CI) 92.6 to 99.5) and 98.4% (95% CI 96.2 to 100), respectively. At 25 years, the corresponding rates of survival were 94.5% (95% CI 89.9 to 99.3) and 98.1% (95% CI 95.7 to 99.6), respectively. There was radiological evidence of stable bony fixation in 86 stems (76.1%) and evidence of loosening in four (3.5%) at 20 years. All patients with radiological evidence of loosening were asymptomatic. Conclusion. The Omnifit HA femoral stem offered promising long-term survival into the third decade. Cite this article: Bone Joint J 2024;106-B(3 Supple A):110–114

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. Aseptic loosening is a leading cause of uncemented arthroplasty failure, often accompanied by fibrotic tissue at the bone-implant interface. A biological target, neutrophil extracellular traps (NETs), was investigated as a crucial connection between the innate immune system’s response to injury, fibrotic tissue development, and proper bone healing. Prevalence of NETs in peri-implant fibrotic tissue from aseptic loosening patients was assessed. A murine model of osseointegration failure was used to test the hypothesis that inhibition (through Pad4-/- mice that display defects in peptidyl arginine deiminase 4 (PAD4), an essential protein required for NETs) or resolution (via DNase 1 treatment, an enzyme that degrades the cytotoxic DNA matrix) of NETs can prevent osseointegration failure and formation of peri-implant fibrotic tissue. Methods. Patient peri-implant fibrotic tissue was analyzed for NETs biomarkers. To enhance osseointegration in loose implant conditions, an innate immune system pathway (NETs) was either inhibited (Pad4-/- mice) or resolved with a pharmacological agent (DNase 1) in a murine model of osseointegration failure. Results. NETs biomarkers were identified in peri-implant fibrotic tissue collected from aseptic loosening patients and at the bone-implant interface in a murine model of osseointegration failure. Inhibition (Pad4-/-) or resolution (DNase 1) of NETs improved osseointegration and reduced fibrotic tissue despite loose implant conditions in mice. Conclusion. This study identifies a biological target (NETs) for potential noninvasive treatments of aseptic loosening by discovering a novel connection between the innate immune system and post-injury bone remodelling caused by implant loosening. By inhibiting or resolving NETs in an osseointegration failure murine model, fibrotic tissue encapsulation around an implant is reduced and osseointegration is enhanced, despite loose implant conditions. Cite this article: Bone Joint J 2021;103-B(7 Supple B):135–144

Aims. Nonagenarians (aged 90 to 99 years) have experienced the fastest percent decile population growth in the USA recently, with a consequent increase in the prevalence of nonagenarians living with joint arthroplasties. As such, the number of revision total hip arthroplasties (THAs) and total knee arthroplasties (TKAs) in nonagenarians is expected to increase. We aimed to determine the mortality rate, implant survivorship, and complications of nonagenarians undergoing aseptic revision THAs and revision TKAs. Methods. Our institutional total joint registry was used to identify 96 nonagenarians who underwent 97 aseptic revisions (78 hips and 19 knees) between 1997 and 2018. The most common indications were aseptic loosening and periprosthetic fracture for both revision THAs and revision TKAs. Mean age at revision was 92 years (90 to 98), mean BMI was 27 kg/m. 2. (16 to 47), and 67% (n = 65) were female. Mean time between primary and revision was 18 years (SD 9). Kaplan-Meier survival was used for patient mortality, and compared to age- and sex-matched control populations. Reoperation risk was assessed using cumulative incidence with death as a competing risk. Mean follow-up was five years. Results. Mortality rates were 9%, 18%, 26%, and 62% at 90 days, one year, two years, and five years, respectively, but similar to control populations. There were 43 surgical complications and five reoperations, resulting in a cumulative incidence of reoperation of 4% at five years. Medical complications were common, with a cumulative incidence of 65% at 90 days. Revisions for periprosthetic fractures were associated with higher mortality and higher 90-day risk of medical complications compared to revisions for aseptic loosening. Conclusion. Contemporary revision THAs and TKAs appeared to be relatively safe in selected nonagenarians managed with multidisciplinary teams. Cause of revision affected morbidity and mortality risks. While early medical and surgical complications were frequent, they seldom resulted in reoperation. Cite this article: Bone Joint J 2023;105-B(6):649–656