Abstract. Introduction. Knee replacement surgery can greatly improve pain, disability, quality of life and ability to work. Socioeconomic deprivation is associated with multiple poor health outcomes, partly due to reduced access to services, including surgery. We investigated whether deprivation was associated with characteristics at presentation, and outcomes following knee arthroplasty. Methodology. We linked data from 2358 knee arthroplasty cases with the Index of Multiple Deprivation, and mortality data after mean 7.6 years follow up. A locally developed scoring system was used prospectively to categorise case complexity. Results. Most patients were from more affluent areas. Deprivation was associated with younger age, and increasing case complexity. There was a significant association between case complexity and mortality, while an independent association between deprivation and mortality could not be confirmed. Conclusion. Health inequalities may impact presentations and outcomes in knee arthroplasty. Patients from areas of socioeconomic deprivation present more complex cases, which may be a result of associated comorbidity and delayed presentation due to impaired access. As knee arthroplasty can improve disability and ability to work, its availability in deprived areas can play a role in the alleviation of health inequality

Introduction: Many papers present results and outcomes of patients undergoing TKR or THR, these are often available to the general population and health care community and health care commissioners. These results are used as a standard to be expected by the interested parties. Patients undergoing lower limb arthroplasty fall into groups that can be broadly divided into standard and complex. Complexity can be further subdivided into local site of surgery problems, general co-morbidity problems or both. We have come up with a 4-part stratification based on the patient’s primary condition and comorbidities and have evaluated this for a single-surgeon cohort of TKR patients and a multi-surgeon group of THR patients. We present the results and the implications of the findings and highlight the usability of the system. Methods: Retrospective review of patient’s notes and radiographs recording lenght of stay, early post operative complications, demographic data, medical co-morbidities and local site of surgery issues. This information was used to stratify patients into 4 groups. Complex Primary 0 -standard joint replacement in a fit patient with simple pattern arthritis, Complex Primary I -a fit patient with locally complex arthritis, Complex Primary II -medically unfit patient with simple arthritis and Complex Primary III -medically unfit patient with complex pattern arthritis. We evaluated this for a single-surgeon cohort of TKR patients and a multi-surgeon group of THR patients, a total of 250 patients. Results: The complication rates between the four groups were analyzed using logistic regression analysis and this revealed a highly significant trend among the four groups (p< 0.0001). Lenght of stay data was analyzed using non-parametric analysis of variance. This revealed a significantly increased lenght of stay in the CI and CII groups compared to the C0 group. Compared to CP0 patients, we found a 3-fold increase in cumulative complication risk in the CPII group, a 4-fold increase in the CPIII group. There were similar trends between CP0 and CPI and between CPI and CPII. Discussion and Conclusion: This classification system correlates and quantifies increasing primary joint replacement complexity with increasing postoperative complication rates and length of stay. It is of use in stratifying patients for preoperative planning, risk counselling, and surgeon selection. These noted increases mean that this system can identify patient groups likely to incur greater cost during their treatment. It is potentially reproducible and usable for other types of surgery and can be applied to larger patient groups via institutional or national joint registries

Aims. The aim of this modified Delphi process was to create a structured Revision Hip Complexity Classification (RHCC) which can be used as a tool to help direct multidisciplinary team (MDT) discussions of complex cases in local or regional revision networks. Methods. The RHCC was developed with the help of a steering group and an invitation through the British Hip Society (BHS) to members to apply, forming an expert panel of 35. We ran a mixed-method modified Delphi process (three rounds of questionnaires and one virtual meeting). Round 1 consisted of identifying the factors that govern the decision-making and complexities, with weighting given to factors considered most important by experts. Participants were asked to identify classification systems where relevant. Rounds 2 and 3 focused on grouping each factor into H1, H2, or H3, creating a hierarchy of complexity. This was followed by a virtual meeting in an attempt to achieve consensus on the factors which had not achieved consensus in preceding rounds. Results. The expert group achieved strong consensus in 32 out of 36 factors following the Delphi process. The RHCC used the existing Paprosky (acetabulum and femur), Unified Classification System, and American Society of Anesthesiologists (ASA) classification systems. Patients with ASA grade III/IV are recognized with a qualifier of an asterisk added to the final classification. The classification has good intraobserver and interobserver reliability with Kappa values of 0.88 to 0.92 and 0.77 to 0.85, respectively. Conclusion. The RHCC has been developed through a modified Delphi technique. RHCC will provide a framework to allow discussion of complex cases as part of a local or regional hip revision MDT. We believe that adoption of the RHCC will provide a comprehensive and reproducible method to describe each patient’s case with regard to surgical complexity, in addition to medical comorbidities that may influence their management. Cite this article: Bone Jt Open 2022;3(5):423–431

Abstract. Introduction. A revision knee replacement (rKR) network model has been introduced in the UK to improve clinical outcomes for patients and reduce healthcare costs. However, the current practice of different types of surgical unit is not well understood. The aim of this study was to answer: “How complex are rKR cases at a Major Revision Centre (MRC)?”. Methodology. Retrospective cohort study at the Nuffield Orthopaedic Centre, Oxford from 2015 - 2018. Case complexity was classified using the Revision Knee Complexity Classification (RKCC). Referral source, technical details of surgery and hospital admission impact were recorded. Results. 688 rKR procedures (380 rKR, 308 re-revision KR) were identified over the study period. 170 rKR (24.7%) were unplanned admissions requiring surgery, whilst the remaining cases were elective. 288/688 rKR (41.9%) were external referrals, where surgical complexity was rated ‘less complex’ (96 rKR, 33.3%), ‘more complex’ (92 rKR, 31.9%) and ‘most complex’ (100 rKR, 34.7%). 140/288 (48.6%) of these cases had one or more rKR prior to referral. Length of stay (LOS) was greater for more complex cases (R1 median 5 days [interquartile range 3–9], R2 median 9 days [IQR 5–15], R3 median 11 days [IQR 7–19]). Conclusion. rKR complexity at the MRC followed a ‘rule of thirds’. Among external referrals, nearly half of patients had a previous rKR prior to referral. More complex cases required longer hospital admissions

Aims. The burden of revision total hip arthroplasty (rTHA) continues to grow. The surgery is complex and associated with significant costs. Regional rTHA networks have been proposed to improve outcomes and to reduce re-revisions, and therefore costs. The aim of this study was to accurately quantify the cost and reimbursement for a rTHA service, and to assess the financial impact of case complexity at a tertiary referral centre within the NHS. Methods. A retrospective analysis of all revision hip procedures was performed at this centre over two consecutive financial years (2018 to 2020). Cases were classified according to the Revision Hip Complexity Classification (RHCC) and whether they were infected or non-infected. Patients with an American Society of Anesthesiologists (ASA) grade ≥ III or BMI ≥ 40 kg/m. 2. are considered “high risk” by the RHCC. Costs were calculated using the Patient Level Information and Costing System (PLICS), and remuneration based on Healthcare Resource Groups (HRG) data. The primary outcome was the financial difference between tariff and cost per patient episode. Results. In all, 199 revision episodes were identified in 168 patients: 25 (13%) least complex revisions (H1); 110 (55%) complex revisions (H2); and 64 (32%) most complex revisions (H3). Of the 199, 76 cases (38%) were due to infection, and 78 patients (39%) were “high risk”. Median length of stay increased significantly with case complexity from four days to six to eight days (p = 0.006) and for revisions performed for infection (9 days vs 5 days; p < 0.001). Cost per episode increased significantly between complexity groups (p < 0.001) and for infected revisions (p < 0.001). All groups demonstrated a mean deficit but this significantly increased with revision complexity (£97, £1,050, and £2,887 per case; p = 0.006) and for infected failure (£2,629 vs £635; p = 0.032). The total deficit to the NHS Trust over two years was £512,202. Conclusion. Current NHS reimbursement for rTHA is inadequate and should be more closely aligned to complexity. An increase in the most complex rTHAs at major revision centres will likely place a greater financial burden on these units. Cite this article: Bone Jt Open 2023;4(8):559–566

Revision total hip arthroplasty (rTHA) can be complex and associated with significant cost, with an increasing burden within the UK and globally. Regional rTHA networks have been proposed aiming to improve outcomes, reduce re-revisions and therefore costs. The aim of this study was to accurately quantify the cost and reimbursement for the rTHA service and to assess the financial impact of case complexity at a tertiary referral centre within the NHS. A retrospective analysis of all revision hip procedures was performed over two consecutive financial years (2018–2020). Cases were classified according to the Revision Hip Complexity Classification (RHCC) and by mode of failure; infected or non-infected. Patients of ASA grade of 3 or greater or BMI over 40 are considered “high-risk” by the RHCC. Costs were calculated using PLICS and remuneration based on the HRG data. The primary outcome was the financial difference between tariff and cost per episode per patient. Comparisons between groups were analysed using analysis of variance and two-tailed unpaired t-test. 199 revision episodes were identified in 168 patients: 25 (13%) least complex revisions (H1), 110 (55%) complex revisions (H2) and 64 (32%) most complex revisions (H3). 76 (38%) cases were due to infection. 78 (39%) of patients were in the “high-risk” group. Median length of stay increased with case complexity from 4, to 6 to 8 days (p=0.17) and significantly for revisions performed for infection (9 vs 5 days; p=0.01). Cost per episode increased significantly between complexity groups (p=0.0002) and for infected revisions (p=0.003). All groups demonstrated a mean deficit, but this significantly increased with revision complexity (£301, £1,820 and £4,757 per case; p=0.02) and for infected failure (£4,023 vs £1,679; p=0.02). The total deficit to the trust for the two-years was £512,202. Current NHS reimbursement for rTHA is inadequate and should be more closely aligned to complexity. An increase in the most complex rTHA at major revision centres (MRC) will likely place a greater financial burden on these units

The Revision Hip Complexity Classification (RHCC) was developed by modified Delphi system in 2022 to provide a comprehensive, reproducible framework for the multidisciplinary discussion of complex revision hip surgery. The aim of this study was to assess the validity, intra-relater and inter-relater reliability of the RHCC. Radiographs and clinical vignettes of 20 consecutive patients who had undergone revision of Total Hip Arthroplasty (THA) at our unit during the previous 12-month period were provided to observers. Five observers, comprising 3 revision hip consultants, 1 hip fellow and 1 ST3-8 registrar were familiarised with the RHCC. Each revision THA case was classified on two separate occasions by each observer, with a mean time between assessments of 42.6 days (24–57). Inter-observer reliability was assessed using the Fleiss™ Kappa statistic and percentage agreement. Intra-observer reliability was assessed using the Cohen Kappa statistic. Validity was assessed using percentage agreement and Cohen Kappa comparing observers to the RHCC web-based application result. All observers were blinded to patient notes, operation notes and post-operative radiographs throughout the process. Inter-observer reliability showed fair agreement in both rounds 1 and 2 of the survey (0.296 and 0.353 respectively), with a percentage agreement of 69% and 75%. Inter-observer reliability was highest in H3-type revisions with kappa values of 0.577 and 0.441. Mean intra-observer reliability showed moderate agreement with a kappa value of 0.446 (0.369 to 0.773). Validity percentage agreement was 44% and 39% respectively, with mean kappa values of 0.125 and 0.046 representing only slight agreement. This study demonstrates that classification using the RHCC without utilisation of the web-based application is unsatisfactory, showing low validity and reliability. Reliability was higher for more complex H3-type cases. The use of the RHCC web app is recommended to ensure the accurate and reliable classification of revision THA cases

Introduction. The Center for Medicare and Medicaid Services (CMS) is faced with a challenge of decreasing the cost of care for total knee arthroplasty (TKA), but must make efforts to prevent patient selection bias in the process. Currently, no appropriate modifier codes exist for primary TKA based on case complexity. We sought to determine differences in perioperative parameters for patients with “complex” primary TKA with the hypothesis that they would require increased cost of care, prolonged care times, and have worse postoperative outcome metrics. Methods. We performed a single center retrospective review from 2015 to 2018 of all primary TKA. Patient demographics, medial proximal tibial angle (mPTA), lateral distal femoral angle (lDFA), flexion contracture, cost of care, and early postoperative outcomes were collected. ‘Complex’ patients were defined as those requiring stems or augments, and multivariable logistic regression analysis and propensity score matching were performed to evaluate perioperative outcomes. Results. 1046 primary TKA were studied and 84 patients (8.3%) were classified as “complex”. For this cohort, surgery duration was greater (117 vs 82 minutes; p<0.001), cost of care excessive (p<0.001), and patients had a greater likelihood for 90-day hospital return. Deviation of mPTA and lDFA was significantly greater preoperatively before and after propensity score matching. Cutpoint analysis demonstrated that preoperative mPTA <83o or >91o, lDFA <84o or >90o, flexion contracture >10o, and BMI > 35.7 were associated with ‘Complex’ procedures. Conclusions. Complex primary TKA may be identifiable preoperatively and are associated prolonged operative time, excess hospital cost of care and increased 90-day hospital returns. This should be considered in future reimbursement models to prevent patient selection bias, and a complexity modifier is warranted

Objectives. The goal of this study is to investigate the relation between indicators of osteoporosis (i.e., bone mineral density (BMD), and Cortical Index (CI)) and the complexity of a fracture of the proximal humerus as a result of a low-energy trauma. Methods. A retrospective chart review of 168 patients (mean age 67.2 years, range 51 to 88.7) with a fracture of the proximal humerus between 2007 and 2011, whose BMD was assessed at the Fracture Liaison Service with Dual Energy X-ray Absorptiometry (DXA) measurements of the hip, femoral neck (FN) and/or lumbar spine (LS), and whose CI and complexity of fracture were assessed on plain anteroposterior radiographs of the proximal humerus. Results. No significant differences were found between simple and complex fractures of the proximal humerus in the BMD of the hip, FN or LS (all p > 0.3) or in the CI (p = 0.14). Only the body mass index was significantly higher in patients with a complex fracture compared with those with a simple fracture (26.9 vs 25.2; p = 0.05). Conclusion. There was no difference in BMD of the hip, FN, LS or CI of the proximal humerus in simple compared with complex fractures of the proximal humerus after a low-energy trauma. Factors other than the BMD and CI, for example body mass index, may play a more important role in the complexity of this fracture. Cite this article: J.W.A.M. den Teuling, B.S. Pauwels, L. Janssen, C.E. Wyers, H. M. J. Janzing, J.P.W. van den Bergh, J. W. Morrenhof. The Influence of bone mineral density and cortical index on the complexity of fractures of the proximal humerus. Bone Joint Res 2017;6:584–589. DOI: 10.1302/2046-3758.610.BJR-2017-0080

Background. Advice and education are considered vital components of back pain care within national guidelines. However, a recent systematic review only found low grade evidence for a small average effect. They also reported wide heterogeneity in intervention design and delivery. This review aimed to understand why intervention design varied and what limited effectiveness by examining the underlying theoretical foundations of the studies from that review. Method. Population, context, selection criteria, intervention(s), control, outcome measures, how the intervention was hypothesised to produce outcomes and author recommendations based on results of the study were extracted from text records. The extent to which the advice included matched a published international consensus statement on evidence-based advice for back pain was recorded. Whether interventions or settings were complex was determined using the Medical Research Council complex intervention development and evaluation guidance and the extent to which they met complexity reporting criteria was recorded. Results. The review included 26 trials conducted over 25 years. Differences In causal pathways could explain diversity in intervention design but these were not clearly described or evaluated. All studies were complex in terms of intervention and setting. This was rarely considered in intervention and trial design or when discussing the results. Although interventions were frequently described in detail only a few explained the process and justification of the design. Theories of education or behaviour change were rarely applied. Conclusion. These studies have not deepened our understanding of how education improves outcomes. Future RCTs should engage more with theory and other theory-based research methods should to be considered. Conflict of interest: No conflicts of interest. Sources of funding: No funding

Cite this article: Bone Joint Res 2023;12(5):306–308.

At our tertiary, large, academic healthcare system, we have access to an academic medical center (AMC), a community based, orthopedic friendly, efficient hospital (CBH) and several ambulatory care centers (ASC) which are being prepared to provide same day discharge (SDD) TJA and UKA. We had a near-capacity AMC with an excellent ability to care for medically and technically complicated TJA patients. However, efficiency was less than desired regardless of case complexity with an average effective case time of 4 hours. Concurrently, the orthopaedically, under-utilized community-based hospital (CBH) wanted to increase volume, improve margins, and become a TJA Center of Excellence with the ability to provide an efficient Hospital Outpatient Department (HOPD) and SDD TJA surgery experience. Methods. The CBH had a main operating floor and a separate floor of four OR suites which were repurposed with the goal of utilizing these rooms for TJA four days per week with an average of 3.5 cases per room per day. We preferentially performed primary, uncomplicated TJA, UKA, and minimally invasive TJA at the CBH. Revision surgeries, patients with extensive medical comorbidities, and complex primary surgeries would be performed at the AMC. Our goals were to decrease costs, readmissions, length of stay, and increase margins at the CBH while increasing efficiency, revenue and volume. Protocols were developed to facilitate SDD UKA and THA at both hospitals as well as rapid recovery protocols for TKA at both hospitals with the understanding that the CBH would perform more of these cases but the efficiency could also be implemented at the AMC when possible. We also needed a strategy to deal with TKA and eventually THA being removed from the Inpatient Only (IPO) list. CMS has utilized the “Two-Midnight Rule” to define outpatient status for both THA and TKA. This has distinct financial implications for the facility's reimbursement with outpatient being $10,123 on average versus $12,380 for inpatient status. A protocol-based system was put in place to make both hospitals compliant with the removal of TKA from the IPO List in order to avoid Quality Improvement Organization (QIO) and Recovery Audit Contractor (RAC) after implementation. Results. Comparing FY 2018 to FY 2019, volume increased 26.4% at the CBH. Outpatient case volume rose substantially from 14 cases to 243. Volumes were slightly decreased at the AMC (−4.57%) resulting in a substantial increase in margin contribution for the parent enterprise. Quality metrics at the CBH (surgical site infections (SSI), length of stay (LOS), readmissions, and mortality) were improved. LOS improved from 52% to 71% discharge before 48 hours. The LOS decreased 12% for THA and 8.1% for TKA. CBH readmission rates decreased from 1.38% to 0.9% with no deaths. Surgeon satisfaction is greatly improved as their volume, efficiency, quality metrics, and finances were enhanced. Financial performance was improved in aggregate and per case for the CBH. Although the CBH per-case revenue was 80.3% and 74.4% of the AMC for THA and TKA: the net margins were 3.6% and 18.8% higher for THA and TKA, respectively. The increased efficiency, lower hospital cost and higher volume at the CBH allowed for an increase in revenue despite lower reimbursement per case. Conclusions. A shifting reimbursement landscape, value-based payment initiatives, and increasing volume have challenged traditional TJA delivery systems. This demonstrates one strategy to help hospital systems improve net margins while improving patient care despite lower net revenue per TJA episode. These strategies will become increasingly important going forward with the transition of higher numbers of TJA patients to outpatient settings including ambulatory surgery centers which will be subjected to even further decreases in net revenue per patient

We have previously noted that patients undergoing primary knee arthroplasty can be broadly divided into standard and complex. Complexity can be further subdivided into local site of surgery issues, general co-morbidity problems or both. On this basis, we devised a simple to apply four-part classification system for patients undergoing primary total knee replacecments (PTKR) to facilitate cumulative risk estimation:. Complex 0 (C0): “Standard” knee replacement in a fit patient with a simple pattern of arthritis. Complex I (CI): A fit patient with a locally complex arthritis pattern. Complex II (CII): Medically unfit patient with a simple pattern of arthritis. Complex III (CIII): Medically unfit patient with a complex arthritis pattern. When a series of consecutive PTKR’s performed by the senior author was grouped according to our classification, all early postoperative complications and length of stay were evaluated and compared. Compared to “standard C0 PTKR patients, we found a 3-fold increase in the cumulative complication risk in the CII group (p< 0.001), a 4-fold increase in the CIII group (p< 0.001) and an increased length of stay in the CIII group (p< 0.001). There were similar trends between C0 and other groups. Further local studies to quantify the cost differentials of treating complex patients and their longer term outcomes and satisfaction are underway. The senior author would like to discuss with the attending members of this BASK meeting the desirability of adopting such a system regionally or nationally, with the potential benefits for individual patients, surgeons, departments, Trusts and the healthcare system as a whole, and whether minor changes could and should be made to the National Joint Registry forms to accommodate this

Aims

Joint registries classify all further arthroplasty procedures to a knee with an existing partial arthroplasty as revision surgery, regardless of the actual procedure performed. Relatively minor procedures, including bearing exchanges, are classified in the same way as major operations requiring augments and stems. A new classification system is proposed to acknowledge and describe the detail of these procedures, which has implications for risk, recovery, and health economics.

To study the surgical outcome of multi-fragmentary, un-reconstructable radial head fractures managed acutely by a radial head prosthetic replacement, we retrospectively reviewed nineteen radial head fractures that were treated acutely with a radial head replacement, over a four-year period in three district general hospitals. Nineteen patients were clinically and radiologically assessed for this study. Functional assessment was performed with the Mayo elbow performance score (MEPS).

No patient achieved full functional range of motion. The average range of flexion was 110° (range 80° to 120°), average extension deficit of 35° (range 30° to 45°), average pronation was 35° (range 0° to 65°), and average supination was 50° (range 30° to 85°). Complications included implant removal due to loosening (n=1), elbow stiffness (n=2), and instability (n=1), the latter case requiring a revision of the radial head prosthesis. Some degree of persistent discomfort was noticed in all cases. Five patients were tolerant of the final functional outcome. The average Mayo elbow score was 68/100 (range 55 to 80). One patient had an intra-operative fracture of the radial metaphysis during insertion of the implant.

Purpose- To study the surgical outcome of multi-fragmentary, un-reconstructable radial head fractures managed acutely by a radial head prosthetic replacement.

Materials- We retrospectively reviewed fifteen radial head fractures that were treated acutely with a radial head replacement, over a four-year period, in three district general hospitals. Fifteen patients were clinically and radiologically assessed for this study. Functional assessment was performed with the Mayo elbow performance score (MEPS).

Results- No patient achieved full functional range of motion. The average range of flexion was 110° (range 80° to 120°), average extension deficit of 35° (range 30° to 45°), average pronation was 35° (range 0° to 65°), and average supination was 50° (range 30° to 85°). Complications included implant removal due to loosening (n=1), elbow stiffness (n=2), and instability (n=1), the latter case requiring a revision of the radial head prosthesis. Some degree of persistent discomfort was noticed in all cases. Five patients were tolerant of the final functional outcome. The average Mayo elbow score was 68/100 (range 55 to 80). One patient had an intra-operative fracture of the radial metaphysis during insertion of the implant.

Conclusions- Radial head replacement in general orthopaedic, low volume, practice failed to achieve satisfactory results. Contrary to popular belief, it is a technically demanding operation, for which surveillance should be continued for a minimum of one year. Strict indications for prosthetic replacement should be followed and implant selection has yet to be proven to make a significant positive contribution.

Our review highlights the need for a stricter adherence to indications, surgery should not be under-estimated and devolved to trainees, and our understanding of the radial axis of the elbow and forearm remains relatively rudimentary.

Aims. The aim of this study was to explore differences in operative autonomy by trainee gender during orthopaedic training in Ireland and the UK, and to explore differences in operative autonomy by trainee gender with regard to training year, case complexity, index procedures, and speciality area. Methods. This retrospective cohort study examined all operations recorded by orthopaedic trainees in Ireland and the UK between July 2012 and July 2022. The primary outcome was operative autonomy, which was defined as the trainee performing the case without the supervising trainer scrubbed. Results. A total of 3,533,223 operations were included for analysis. Overall, male trainees performed 5% more operations with autonomy than female trainees (30.5% vs 25.5%; 95% CI 4.85 to 5.09). Female trainees assisted for 3% more operations (35% vs 32%; 95% CI 2.91 to 3.17) and performed 2% more operations with a supervising trainer scrubbed (39% vs 37%; 95% CI 1.79 to 2.06). Male trainees performed more operations with autonomy than female trainees in every year of training, in each category of case complexity, for each orthopaedic speciality area, and for every index procedure except nerve decompression. When adjusting for year, training level, case complexity, speciality area, and urgency, male trainees had 145% (95% CI 2.18 to 2.76) increased odds of performing an operation with autonomy and 35% (95% CI 1.25 to 1.45) increased odds of performing an operation under trainer supervision, than assisting, compared to female trainees. Conclusion. Male trainees perform more operations with autonomy during orthopaedic training than female trainees. Female orthopaedic trainees assist for a greater proportion of cases than their male counterparts. A comprehensive review of trauma and orthopaedic training is needed to identify any additional differences in training opportunities between female and male trainees, particularly with regard to progression through training. Cite this article: Bone Jt Open 2025;6(1):62–73

Articulating cartilage experiences a multitude of biophysical cues. Due to its primary function in distributing load with near frictionless articulation, it is clear that a major stimulus for cartilage homeostasis and regeneration is the mechanical load it experiences on a daily basis. While these effects are considered when performing in vivo studies, in vitro studies are still largely performed under static conditions. Therefore, an increasing complexity of in vitro culture models is required, with the ultimate aim to recreate the articulating joint as accurately as possible. We have for many years utilized a complex multiaxial load bioreactor capable of applying tightly regulated compression and shear loading protocols. Using this bioreactor, we have been able to demonstrate the mechanical induction of human bone marrow stromal cell (BMSC) chondrogenesis in the absence of exogenous growth factors. Building on previous bioreactor studies that demonstrated the mechanical activation of endogenous TGFβ, and subsequent chondrogenesis of human bone marrow derived MSCs, we have been further increasing the complexity of in vitro models. For example, the addition of high molecular weight hyaluronic acid, a component of synovial fluid, culture medium leads to reduced hypertrophy and increased glycosaminoglycan deposition. The ultimate aim of all of these endeavors is to identify promising materials and therapies during in vitro/ ex vivo studies, therefore reducing the numbers or candidates that are finally tested using in vivo studies. This 3R approach can improve the opportunities for success while leading to more ethically acceptable product development pathways

Aim. Periprosthetic Joint Infection (PJI) is a devastating complication in hip and knee joint arthroplasty. The “JS BACH” classification system was developed in 2021 to stratify the complexity of PJI, and more importantly, to act as a tool to guide referrals to specialist centers. The “JS BACH” classification has not been validated in an external cohort. This study aimed to do so using a large prospective cohort from Australia and New Zealand. Method. We applied the JS-BACH classification to the Prosthetic Joint Infection in Australia and New Zealand Observational (PIANO) cohort. This prospective study of newly diagnosed PJI collected 2-year outcome data from 653 participants enrolled in 27 hospitals. The definition of PJI treatment failure at 24 months was any of the following: death, clinical or microbiological signs of infection, destination prosthesis removed, or ongoing antibiotic use. Results. Individual cases were classified as per JS-BACH into “1 - uncomplicated” (n = 268), “2 - complex” (n = 330), and “3 - limited options” (n = 55). This cohort was similar to the original JS-BACH population in terms of baseline characteristics. However, there was a difference in complexity, with more DAIR procedures, fewer revision procedures, and a higher proportion of uncomplicated patients in the PIANO cohort. The risk of treatment failure correlated strongly with the JS-BACH category, with odds ratios (95% CI [confidence interval]) for category 2 versus 1 of 1.75 (1.24 to 2.47) and for category 3 versus 1 of 7.12 (3.42 to 16.02). Conclusions. Despite the PIANO study population being less complicated than the original derivation cohort, the JS-BACH classification showed a clear association with treatment failure in this large external cohort

The purpose of this study was to determine whether there have been changes in the complexity of femoral fragility fractures presenting to our Dunedin Orthopaedic Department, New Zealand, over a period of ten years. Patients over the age of 60 presenting with femoral fragility fractures to Dunedin Hospital in 2009 −10 (335 fractures) were compared with respect to demographic data, incidence rates, fracture classification and treatment details to the period 2018-19 (311 fractures). Pathological and high velocity fractures were excluded. The gender proportion and average age (83.1 vs 83.0 years) was unchanged. The overall incidence of femoral fractures in people over 60 years in our region fell by 27% (p<0.001). Intracapsular fractures (31 B1 and B2) fell by 29% (p=0.03) and stable trochanteric fractures by 56% (p<0.001). The incidence of unstable trochanteric fractures (31A2 and 31A3) increased by 84.5% from 3.5 to 6.4/10,000 over 60 years (p = 0.04). The proportion of trochanteric fractures treated with an intramedullary (IM) nail increased from 8% to 37% (p <0.001). Fewer intracapsular fractures were treated by internal fixation (p<0.001) and the rate of acute total hip joint replacements increased from 13 to 21% (p=0.07). The incidence of femoral shaft fractures did not change significantly with periprosthetic fractures comprising 70% in both cohorts. While there has been little difference in the numbers there has been a decrease in the incidence of femoral fragility fractures likely due to the increasing use of bisphosphonates. However, the incidence of unstable trochanteric fractures is increasing. This has led to the increased use of IM nails which are increasingly used for stable fractures as well. The increasing complexity of femoral fragility fractures is likely to have an impact on implant use, theatre time and cost