Results in patients undergoing total hip arthroplasty (THA) for femoral head osteonecrosis (ON) when compared with primary osteoarthritis (OA) are controversial. Different factors like age, THA type or surgical technique may affect outcome. We hypothesized that patients with ON had an increased revision rate compared with OA. We analysed clinical outcome, estimated the survival rate for revision surgery, and their possible risk factors, in two groups of patients.

In this retrospective cohort analysis of our prospective database, we assessed 2464 primary THAs implanted between 1989 and 2017. Patients with OA were included in group 1, 2090 hips; and patients with ON in group 2, 374 hips. In group 2 there were more men (p<0.001), patients younger than 60 years old (p<0.001) and with greater physical activity (p<0.001). Patients with lumbar OA (p<0.001) and a radiological acetabular shape type B according to Dorr (p<0.001) were more frequent in group 1. Clinical outcome was assessed according to the Harris Hip Score and radiological analysis included postoperative acetabular and femoral component position and hip reconstruction. Kaplan-Meier survivorship analysis was used to estimate the cumulative probability of not having revision surgery for different reasons. Univariate and multivariate Cox regression models were used to assess risk factors for revision surgery.

Clinical improvement was better in the ON at all intervals. There were 90 hips revised, 68 due to loosening or wear, 52 (2.5%) in group 1, and 16 (4.3%) in group 2. Overall, the survival rate for revision surgery for any cause at 22 years was 88.0 % (95% CI, 82-94) in group 1 and 84.1% (95% CI, 69 – 99) in group 2 (p=0.019). Multivariate regression analysis showed that hips with conventional polyethylene (PE), compared with highly-cross linked PEs or ceramic-on-ceramic bearings, (p=0.01, Hazard Ratio (HR): 2.12, 95% CI 1.15-3.92), and cups outside the Lewinnek´s safe zone had a higher risk for revision surgery (p<0.001, HR: 2.57, 95% CI 1.69-3.91).

Modern highly-cross linked PEs and ceramic-on-ceramic bearings use, and a proper surgical technique improved revision rate in patients undergoing THA due to ON compared with OA.

Abstract. Objectives. Obesity is prevalent with nearly one third of the world's population being classified as obese. Total knee arthroplasty (TKA) is an effective treatment option for high BMI patients achieving similar outcomes to non-obese patients. However, increased rates of aseptic loosening in patients with a high BMI have been reported. In patients with high BMI/body mass there is an increase in strain placed on the implant fixation interfaces. As such component fixation is a potential concern when performing TKA in the obese patient. To address this concern the use of extended tibial stems in cemented implants or cementless fixation have been advocated. Extend tibial stems are thought to improve implant stability reducing the micromotion between interfaces and consequently the risk of aseptic loosening. Cementless implants, once biologic fixation is achieved, effectively integrate into bone eliminating an interface. This retrospective study compared the use of extended tibial stems and cementless implants to conventional cemented implants in high BMI patients. Methods. From a prospectively maintained database of 3239 primary Attune TKA (Depuy, Warsaw, Indiana), obese patients (body mass index (BMI) >30 kg/m²) were retrospectively reviewed. Two groups of patients 1) using a tibial stem extension [n=162] and 2) cementless fixation [n=163] were compared to 3) a control group (n=1426) with a standard tibial stem cemented implant. All operations were performed by or under the direct supervision of specialist arthroplasty surgeons. Analysis compared the groups with respect to class I, II, and III (BMI >30kg/m², >35 kg/m², >40 kg/m²) obesity. The primary outcome measures were all-cause revision, revision for aseptic loosening, and revision for tibial loosening. Kaplan-Meier survival analysis and Cox regression models were used to compare the primary outcomes between groups. Where radiographic images at greater than 3 months post-operatively were available, radiographs were examined to compare the presence of peri-implant radiolucent lines. Results. The mean follow-up of 4.8, 3.4, and 2.5 years for cemented, stemmed, and cementless groups respectively. In total there were 34 all-cause revisions across all the groups with revision rates of 4.55, 5.50, and 0.00 per 1000-implant-years for cemented, stemmed, and cementless groups respectively. Survival Analysis did not show any significant differences between the three groups for all-all cause revision. There were 6 revisions for aseptic loosening (5 tibial and 1 femoral); all of which were in the standard cemented implant group. In contrast there were no revisions in the stemmed or cementless implant groups, however, this was not significant on survival analysis. Analysis looking at class I, II, and III obesity also did not show any significant differences in survival for all cause revision or aseptic loosening. Conclusion. This retrospective analysis showed that there were no revisions required for aseptic loosening when either a cemented stemmed or cementless implant were used in obese patients. These findings are in line with other studies showing that cementless fixation or extended stem implants are a reasonable option in obese patients who represent an increasing cohort of patients requiring TKR. Declaration of Interest. (b) declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research reported:I declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project

Abstract. Objective. Up to 20% of patients can remain dissatisfied following TKR. A proportion of TKRs will need early revision with aseptic loosening the most common. The ATTUNE TKR was introduced in 2011 as successor to its predicate design The PFC Sigma (DePuy Synthes, Warsaw, In). However, following reports of early failures of the tibial component there have been ongoing concerns of increased loosening rates with the ATTUNE TKR. In 2017 a redesigned tibial baseplate (S+) was introduced, which included cement pockets and an increased surface roughness to improve cement bonding. Given the concerns of early tibial loosening with the ATTUNE knee system, this study aimed to compare revision rates and those specific to aseptic loosening of the ATTUNE implant in comparison to an established predicate as well as other implant designs used in a high-volume arthroplasty centre. Methods. The Attune TKR was introduced to our unit in December 2011. Prior to this we routinely used a predicate design with an excellent long-term track record (PFC Sigma) which remains in use. In addition, other designs were available and used as per surgeon preference. Using a prospectively maintained database, we identified 10,202 patients who underwent primary cemented TKR at our institution between 01/04/2003–31/03/2022 with a minimum of 1 year follow-up (Mean 8.4years, range 1–20years): 1) 2406 with ATTUNE TKR (of which 557 were S+) 2) 4652 with PFC TKR 3) 3154 with other cemented designs. All implants were cemented using high viscosity cement. The primary outcome measures were all-cause revision, revision for aseptic loosening, and revision for tibial loosening. Kaplan-Meier survival analysis and Cox regression models were used to compare the primary outcomes between groups. Matched cohorts were selected from the ATTUNE subsets (original and S+) and PFC groups using the nearest neighbor method for radiographic analysis. Radiographs were assessed to compare the presence of radiolucent lines in the Attune S+, standard Attune, and PFC implants. Results. At a mean of 8.4 years follow-up, 308 implants underwent revision equating to 3.58 revisions per 1000 implant-years. The lowest risk of revision was noted in the ATTUNE cohort with 2.98 per 1000-implant-years where the PFC and All Other Implant groups were 3.15 and 4.4 respectively. Aseptic loosing was the most common cause for revision across all cemented implants with 76% (65/88) of involving loosening of the tibia. Survival analysis comparing the ATTUNE cohort to the PFC and All Other Cemented Implant cohorts showed no significant differences for: all-cause revision, aseptic loosening, or tibial loosening (p=0.15,0.77,0.47). Radiolucent lines were detected in 4.6%, 5.8%, and 5.0% of the ATTUNE S+, standard ATTUNE, and PFC groups respectively. These differences were not significant. Conclusion. This study represents the largest non-registry review of the original and S+ ATTUNE TKR in comparison to its predicate design as well as other cemented implants. There appears to be no significant increased revision rate for all-cause revision or aseptic loosening. Radiographic analysis also showed no significant difference in peri-implant radiolucency. It appears that concerns of early loosening may be unfounded. Declaration of Interest. (a) fully declare any financial or other potential conflict of interest

Background. The worldwide withdrawal of the DePuy Articular Surface Replacement (ASR) device in both its resurfacing and total hip replacement (THR) form on 26 August 2010, after 93,000 were implanted worldwide, has had major implications. The 2010 National Joint Registry for England and Wales quoted figures of 12-13% failure at five years; however these figures may be an underestimate. Patients and methods. In 2004 a single surgeon prospective study of the ASR bearing surface was undertaken. Presented are the Adverse Reaction to Metal Debris (ARMD) failure rates of the ASR resurfacing and ASR THR systems. The diagnosis of ARMD was made by the senior author and was based on clinical history, examination, ultrasound findings, metal ion analysis of blood and joint fluid, operative findings and histopathological analysis of tissues retrieved at revision. Acetabular cup position in vivo was determined using EBRA software. Mean follow up was 52 months (24-81) and 70 patients were beyond 6 years of the procedure at the time of writing. Kaplan Meier survival analysis was carried out firstly with joints designated ‘failure’ if the patient had undergone revision surgery or if the patient had been listed for revision. A second survival analysis was carried out with a failure defined as a serum cobalt concentration > 7microgrammes/L (MHRA guideline from MDA-2010-069). Full explant analysis was carried out for retrieved prostheses. Results. There were 505 ASR hips in total (418 resurfacings and 87 THRs). 657 metal ion samples were available at the time of writing including 152 repeats. Survival analysis using revision/listed for revision as end point (at 6 years): ASR resurfacing: 26.1% failure; ASR THR: 55.5% failure. Survival using ion analysis (at 5 years): ASR resurfacing: 50.1% failure; ASR THR: 66.5% failure. The median (range) volumetric wear rate of failed prostheses was 8.23mm3/year (0.51-95.5). Failure and high ion concentrations are linked to acetabular cup size, anteversion and inclination. Increased failure rates in THRs were due to wear at the taper junction of head and stem. Conclusion. Design flaws in the ASR have led to excessive wear and consequently catastrophic failure rates secondary to ARMD

Background and aims. Hallux rigidus in the metatarsophalangeal joint (MTPJ) can be treated with arthroplasty to reduce pain and enhance motion. Few studies have investigated the functionality and the survival of HemiCap arthroplasty. Primarily we aimed to examine the medium to long-term functionality and the degree of pain after surgery. Secondarily the failure and revision rate of HemiCap implants. Methods. A total of 106 patients were operated with HemiCap arthroplasty (n=114) from 2006 to 2014, median age 53 (16 to 80) years, 78 females, 37 dorsal flange (DF) implants. Patient charts were reviewed retrospectively to collect revision data. Pre operative Coughlin/Shurnas arthrosis degree, hallux valgus (HV), intermetatarsalintermetatarsal (IM) and Distal Metaphyseal Articular Angle (DMAA) angles was were measured. Pre- and post operative 3 weeks, 6 months, 1 and 2 year2-year pain levels of the first MTPJ by Visuel Analog Skala (VAS 1–10), American Orthopaedic Foot and Ankle Score (AOFAS 0 to 100 points) and, Range of Motion (ROM), were available for 51 patients. FortysevenForty-seven of the 70 available for reexamination partook in a cross sectional follow up where the Self-Reported Foot and Ankle Score (SEFAS 0–48 points) was added to the Patients Related Outcome Measures (PROMs). Statistics. Kaplan-Meier for survival analysis, adjusted for sex, radiological angles, degree of arthrosis and dorsal flange. Prospective PROMs and ROM compared by paired t-test. Results. At 3, 5 and 7 years we had an mean implant survival of 85%, 83% and 78%. Almost all were revised due to pain, one due to malalignment and one due to loosening of the Hemicap. Dorsal flange, gender, preoperative arthrosis degree, HV, IM or DMAA angles did not statistically influence the result. For those (n=23) that were re-examined, preoperative dorsal ROM changed from mean(sd) 21 (6) to 42 (18) degrees, VAS from 7 (2) to 2 (2) and AOFAS from 61 (11) to 87 (11) (p < 0.001). At mean 5 year follow up (n=47), mean (sd) dorsal ROM was 46 (17) degrees,. AOFAS was 84 (9), VAS 2 (1) and SEFAS 42 (6) points. The dorsal flange made no statistical significant difference for ROM or PROMs, but DF displayed 51 degrees of extension vs. 44 without (p=0.1). Periprostethic lucency (<2 mm) was observed in 27/47. Conclusions. In general, we saw an acceptable implant survival rate. We did not find any predictors that influenced implant failure and the design alterations with the dorsal flange are not evident clinically. Patients who were not revised had significantly less pain, greater ROM, and better overall foot and ankle conditions than preoperatively, but the data are biased by missing numbers and revisions

Background. In the United Kingdom (UK), the fastest growing population demographic is the over 85 years of age, but despite this, outcomes achieved in the octogenarian population with a Unicompartmental Knee Replacement (UKR) are underrepresented in the literature. The Elective Orthopaedic Centre, Epsom, has an established patient reported outcome measures (PROMs) programme into which all patients are routinely enrolled. We aim to investigate the outcome of medial UKR using the oxford phase 3 implant in octogenarians. Methods. We retrospectively reviewed our database for patients aged 60–89 years, who underwent a medial unicompartmental Knee Replacement (UKR) using the oxford phase 3 implant, between June 2007-December 2012 (N=395). The patients were stratified into 3 groups based on age, 60–69 (N=188), 70–79(N=149), and 80–89(N=58). Oxford Knee Scores (OKS), Euro-quol (EQ-5D) scores, revision rates, and mortality were compared. Results. We found that the octogenarian group achieved considerable improvement at 1 year with a mean OKS of 39.2 (+/−7.193) and EQ-5D score of 0.791(+/−0.241). And this improvement remained significant at 2 years. There was no difference in functional outcome when the 3 groups were compared. Revision rates for the 3 groups from youngest to oldest were, 8.5%, 4.5%, and 6.9% respectively. Odds ratio and survival analysis showed no significant difference between the groups. Conclusion. In conclusion, we found that octogenarians over a 2 year period achieved similar functional outcome as their younger counterparts. Level of Evidence. IV

Introduction. The two-dimensional (2D) monolayer culture paradigm has limited translational potential to physiological systems; chondrocytes and tenocytes in monolayer lose expression of hallmarks of differentiated status (dedifferentiation). Qualitative assessment of three-dimensional (3D) cultures in musculoskeletal biology relative to native tissues has been limited. An understanding of prevailing gene regulatory networks is required to define whether 3D culture systems faithfully restitute the native tissue phenotype (redifferentiation). Using a systems biology approach to explore the gene networks associated with de- and re-differentiation may define targetable regulators associated with phenotypic plasticity of adult musculoskeletal cells. Materials and Methods. Global transcriptomic and proteomic profiling of matrix-depleted chondrocytes and tenocytes from the rat was performed for each of three conditions (native tissue, monolayer at passage three, or tissue-appropriate 3D cultures). Differential analysis of mRNA and protein abundance, gene ontology annotation, pathway topology impact analysis, and derivation of common mechanistic networks was undertaken to define consensus expression profiles, signalling pathways, and upstream regulators for de- and re-differentiation in each cell type. Results. Principal component analysis demonstrated a convergence of gene expression profiles in monolayer, including the expression of musculoskeletal progenitor markers scleraxis (Scx) and Mohawk (Mkx). Three-dimensional culture systems failed to demonstrate parity with native tissue and incited the expression of Il-6 and Ptgs2 (COX2). The CCN-family member Ctgf (CCN2), and the marker of skeletal differentiation Grem1 (gremlin 1), were consistently differentially abundant in de- and re-differentiation at both the mRNA and protein level. Pathway topology impact analysis defined PI-3K/Akt as the common signalling pathway in de- and re-differentiation. Discussion. Historically, the terms de- and re-differentiation have been used with no mechanistic definition. Additionally, there is no standardised phenotype for 3D cultures to benchmark novel progress in bioengineering. Consensus upstream regulators yielded a unified mechanistic network for chondrocyte and tenocyte phenotypes in three conditions. The PI-3K/Akt signalling pathway has been implicated in a range of physiological activities including dedifferentiation, proliferation, matrix synthesis, and cell survival. Pathway analysis suggests that the PI-3K/Akt signalling pathway may contribute to the de- and re-differentiation phenotypes for both chondrocytes and tenocytes and represents a rational target for further network-level analysis