Aims. Two-stage exchange revision total hip arthroplasty (THA) performed in case of periprosthetic joint infection (PJI) has been considered for many years as being the gold standard for the treatment of chronic infection. However, over the past decade, there have been concerns about its safety and its effectiveness. The purposes of our study were to investigate our practice, collecting the overall spacer complications, and then to analyze their risk factors. Methods. We retrospectively included 125 patients with chronic hip PJI who underwent a staged THA revision performed between January 2013 and December 2019. All spacer complications were systematically collected, and risk factors were analyzed. Statistical evaluations were performed using the Student's t-test, Mann-Whitney U test, and Fisher's exact test. Results. Our staged exchange practice shows poor results, which means a 42% mechanical spacer failure rate, and a 20% recurrent infection rate over the two years average follow-up period. Moreover, we found a high rate of spacer dislocation (23%) and a low rate of spacer fracture (8%) compared to the previous literature. Our findings stress that the majority of spacer complications and failures is reflecting a population with high comorbid burden, highlighted by the American Society of Anesthesiology grade, Charlson Comorbidity Index, and Lee score associations, as well as the cardiac, pulmonary, kidney, or hepatic chronic conditions. Conclusion. Our experience of a two-stage hip exchange revision noted important complication rates associated with high failure rates of polymethylmethacrylate spacers. These findings must be interpreted in the light of the patient’s comorbidity profiles, as the elective population for staged exchange has an increasing comorbid burden leading to poor results. In order to provide better results for this specific population, our conclusion suggests that comparative strategy studies are required to improve our therapeutic indication. Cite this article: Bone Jt Open 2022;3(6):485–494

Aims. To determine ten-year failure rates following 36 mm metal-on-metal (MoM) Pinnacle total hip arthroplasty (THA), and identify predictors of failure. Patients and Methods. We retrospectively assessed a single-centre cohort of 569 primary 36 mm MoM Pinnacle THAs (all Corail stems) followed up since 2012 according to Medicines and Healthcare Products Regulation Agency recommendations. All-cause failure rates (all-cause revision, and non-revised cross-sectional imaging failures) were calculated, with predictors for failure identified using multivariable Cox regression. Results. Failure occurred in 97 hips (17.0%). The ten-year cumulative failure rate was 27.1% (95% confidence interval (CI) 21.6 to 33.7). Primary implantation from 2006 onwards (hazard ratio (HR) 4.30; 95% CI 1.82 to 10.1; p = 0.001) and bilateral MoM hip arthroplasty (HR 1.59; 95% CI 1.03 to 2.46; p = 0.037) predicted failure. The effect of implantation year on failure varied over time. From four years onwards following surgery, hips implanted since 2006 had significantly higher failure rates (eight years 28.3%; 95% CI 23.1 to 34.5) compared with hips implanted before 2006 (eight years 6.3%; 95% CI 2.4 to 15.8) (HR 15.2; 95% CI 2.11 to 110.4; p = 0.007). Conclusion. We observed that 36 mm MoM Pinnacle THAs have an unacceptably high ten-year failure rate, especially if implanted from 2006 onwards or in bilateral MoM hip patients. Our findings regarding implantation year and failure support recent concerns about the device manufacturing process. We recommend all patients undergoing implantation since 2006 and those with bilateral MoM hips undergo regular investigation, regardless of symptoms. Cite this article: Bone Joint J 2017;99-B:592–600

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

Aim. Infection is one of the worst complications following total joint arthroplasty, which is often associated with significant morbidity. Currently, due to the global burden of multidrug-resistant Gram-negative bacteria (MDR-GNB) infections, few multicentre studies have described a microbiological shift from Gram-positive cocci (GPC) towards MDR-GNB PJI (prosthetic joint infection). Additionally, the emergence of MDR-GNB impacts the therapeutic options and may increase the rate of PJI treatment failure. The purpose of the present study was to describe the predisposing factors associated to failure of treatment in an orthopaedic reference hospital in Brazil from 2014 through 2019. Method. Retrospective case-control analysis of patients treated for MDR-GNB PJI over a five-year period. Data were collected from medical, surgical and laboratory records. PJI were defined according the current MSIS criteria. MDR was defined as non-susceptibility to at least one agent in three or more antimicrobial categories. Patients with PJI with at least two positive tissue cultures for MDR-GNB were selected. The control group was patient with PJI caused by multisensitive organism (GNB or GPC). Absence of signs and symptoms of infection during the follow-up period was defined as cure. Definition of failure: death, need for another course of antibiotic, or the need for another surgical procedure to control the infectious site (relapse). Results. A total of 104 patients were selected, 59 patients in the MDR-GNB PJI group and 44 in the control group. Two outcomes were compared: cure or failure. The overall 1-year survival rate was 65.3% with the median survival time being 207.08 days. In the MDR-BGN infection group the 1-year survival rate was 59.3% and the average time of survival was 141.14 days. In contrast, in the Control group the 1-year survival rate was 73.8% with an average survival time of 230.29 days (p = 0.023). HR: 2.447, IC 1.099–5.448. The independent variables in the multivariate analysis associated to treatment failure were MDR-BGN infection (p = 0.023) HR 2,447 IC 1,099 –5,448, revision surgery (p = 0.042) HR 2,027 IC: 2,027–4,061, presence of comorbidities (p = 0.048) HR 2,508 IC: 0,972- 6,469 and previous antimicrobial use in the last 3 months (p = 0.022). HR 2,132 IC: 1,096- 4,149. Conclusions. GNB-MDR PJI increases approximately 2.5 times the chance of unfavourable outcome such as death and infectious relapse compared to infections with other multisensitive microorganism

Aims. The aims of this study were to identify and evaluate the current literature examining the prognostic factors which are associated with failure of total elbow arthroplasty (TEA). Methods. Electronic literature searches were conducted using MEDLINE, Embase, PubMed, and Cochrane. All studies reporting prognostic estimates for factors associated with the revision of a primary TEA were included. The risk of bias was assessed using the Quality In Prognosis Studies (QUIPS) tool, and the quality of evidence was assessed using the modified Grading of Recommendations, Assessment, Development, and Evaluations (GRADE) framework. Due to low quality of the evidence and the heterogeneous nature of the studies, a narrative synthesis was used. Results. A total of 19 studies met the inclusion criteria, investigating 28 possible prognostic factors. Most QUIPS domains (84%) were rated as moderate to high risk of bias. The quality of the evidence was low or very low for all prognostic factors. In low-quality evidence, prognostic factors with consistent associations with failure of TEA in more than one study were: the sequelae of trauma leading to TEA, either independently or combined with acute trauma, and male sex. Several other studies investigating sex reported no association. The evidence for other factors was of very low quality and mostly involved exploratory studies. Conclusion. The current evidence investigating the prognostic factors associated with failure of TEA is of low or very low quality, and studies generally have a moderate to high risk of bias. Prognostic factors are subject to uncertainty, should be interpreted with caution, and are of little clinical value. Higher-quality evidence is required to determine robust prognostic factors for failure of TEA. Cite this article: Bone Joint Res 2024;13(5):201–213

Several attempts have been made to treat medial compartment OA of the knee with mobile spacers. All have met with dismal failure. This presentation explores the history of attempts to treat OA in the younger knee with mobile spacers and explains why they were all doomed to fail. Sources of information for this presentation include the published peer reviewed literature, publically available documents, and an insiders view of some of the failed attempts to solve the problem of medial compartment OA with mobile spacers. All attempts to treat medial compartment OA of the knee with mobile spacers have failed. The unispacer has been a failure with a 60% revision rate at three years. The ABS intercushion had a 100% revision rate at one year and in many cases caused permanent damage to the host knees. The Salucartilage spacer was implanted in one patient only and failed within 48 hours. Mobile spacers do not work, are never likely to work, and are not indicated for the treatment of medial compartment osteoarthritis of the knee

Background. Total knee prostheses are continually being redesigned to improve performance, longevity and closer mimic kinematics of the native knee. Despite continued improvements, all knee implants even those with proven design features, have failures. We identified a cohort of patients with isolated tibial component failures that occurred in a popular and successful knee system. Our purpose was to (1) characterize the observed radiographic failure pattern; (2) investigate the biologic response that may contribute to the failure; and (3) to determine if the failure mechanism was of a biological or a mechanical nature. Methods. Twenty-one knees from 19 patients met the inclusion criteria of having isolated tibial component failure in a commonly used knee implant system. Radiographs from the primary and revision knee surgery were analyzed for implant positioning and failure pattern, respectively. Inflammatory biomarkers IL-1β, IL-6 and TNF-α were available in 16/21 knees and peripheral CD14. +. /16. +. monocytes were measured in 10 of the above mentioned 16 knee revisions. Additionally, white blood cell (WBC) count, erythrocyte sedimentation rate (ESR), and C-reactive protein (CRP) were measured to rule out infection as the cause of the cytokine upregulation. Results. Radiograph findings demonstrated that all of the 21 tibial components were implanted in either neutral or 2–3° varus position, none of the revisions were implanted in valgus (figure 1). All tibias showed obvious radiographic loosening and failed into varus. The inflammatory biomarkers IL-1b, IL-6, & TNF-a were negative. WBC, ESR, CRP were normal. Peripheral CD14+/16+ and total CD16+ monocytesmeasurements were consistent with previous findings of patients with osteoarthritis (figure 2). Conclusions. The findings supported a mechanical failure mechanism rather than that of a wear debris induced inflammatory pattern. The loosening, collapse and debonding from the cement may have been related to the implantation technique, stresses due to rotational freedom of the implant, or patient characteristics/behavior. For any figures or tables, please contact authors directly (see Info & Metrics tab above).

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

Polymethylmethacrylate (PMMA) bone cement is strong in compression, however it tends to fail under torsion. Sufficient pressurisation and subsequent interdigitation between cement and bone are critical for the mechanical interlock of cemented orthopaedic implants, and an irregular surface on the acetabular cup is necessary for reasonable fixation at the cup-cement interface. There is limited literature investigating discrepancies in the failure mechanisms of cemented all-polyethylene acetabular cups with and without cement spacers, under torsional loading. In vitro experimental comparison of three groups of polyethylene acetabular prosthesis (PAP) cemented into prepared sawbone hemipelvises:. * PAP without PMMA spacers maintaining an equal cement mantle circumferentially. (Group 1 n=3). * PAP without PMMA spacers cemented deliberately ‘bottoming-out’ the implant within the acetabulum. (Group 2 n=3). * PAP with PMMA spacers. (Group 3 n=3). The constructs were tested to torstional failure on a custom designed setup, and statistical analysis done by a one-way ANOVA and Tukey-Welsh test. Group 3 demonstrated superior torsional resistance with a statistically significant torque of 145Nm (SD±12Nm) at failure, compared to group 2 (109Nm, SD±7Nm) and group 1 (99Nm, SD±8Nm). Group 3 experienced failure predominantly at the bone-cement interface, in contrast, Groups 1 and 2 exhibited failure predominantly at the cup-cement interface. There was no significant difference between Group 1 and 2. Qualitative analysis of the failure mode indicates the efficient redistribution of stress throughout the cement mantle, consistent with the greater uniformity of cement. PMMA spacers increase the resistance to torsional failure at the implant-cement interface. Acetabular components without spacers (Groups 1 and 2) failed at the implant-cement interface before the cement-bone interface, at a statistically significantly lower level of torque to failure. Although the PMMA spacers may reduce cement interdigitation at the cement-bone interface the torsional forces required to fail are likely supraphysiological

Aims. One-stage exchange for periprosthetic joint infection (PJI) in total hip arthroplasty (THA) is gaining popularity. The outcome for a repeat one-stage revision THA after a failed one-stage exchange for infection remains unknown. The aim of this study was to report the infection-free and all-cause revision-free survival of repeat one-stage exchange, and to investigate the association between the Musculoskeletal Infection Society (MSIS) staging system and further infection-related failure. Methods. We retrospectively reviewed all repeat one-stage revision THAs performed after failed one-stage exchange THA for infection between January 2008 and December 2016. The final cohort included 32 patients. The mean follow-up after repeat one-stage exchange was 5.3 years (1.2 to 13.0). The patients with a further infection-related failure and/or all-cause revision were reported, and Kaplan-Meier survival for these endpoints determined. Patients were categorized according to the MSIS system, and its association with further infection was analyzed. Results. A total of eight repeat septic revisions (25%) developed a further infection-related failure, and the five-year infection-free survival was 81% (95% confidence interval (CI) 57 to 92). Nine (28%) underwent a further all-cause revision and the five-year all-cause revision-free survival was 74% (95% CI 52 to 88). Neither the MSIS classification of the host status (p = 0.423) nor the limb status (p = 0.366) was significantly associated with further infection-related failure. Conclusion. Repeat one-stage exchange for PJI in THA is associated with a favourable five-year infection-free and all-cause revision-free survival. Notably, the rate of infection control is encouraging when compared with the reported rates after repeat two-stage exchange. The results can be used to counsel patients and help clinicians make informed decisions about treatment. With the available number of patients, further infection-related failure was not associated with the MSIS host or limb status. Cite this article: Bone Joint J 2022;104-B(1):27–33

Aims. A higher failure rate has been reported in haematogenous periprosthetic joint infection (PJI) compared to non-haematogenous PJI. The reason for this difference is unknown. We investigated the outcome of haematogenous and non-haematogenous PJI to analyze the risk factors for failure in both groups of patients. Methods. Episodes of knee or hip PJI (defined by the European Bone and Joint Infection Society criteria) treated at our institution between January 2015 and October 2020 were included in a retrospective PJI cohort. Episodes with a follow-up of > one year were stratified by route of infection into haematogenous and non-haematogenous PJI. Probability of failure-free survival was estimated using the Kaplan-Meier method, and compared between groups using log-rank test. Univariate and multivariate analysis was applied to assess risk factors for failure. Results. A total of 305 PJI episodes (174 hips, 131 knees) were allocated to the haematogenous (n = 146) or the non-haematogenous group (n = 159). Among monomicrobial infections, Staphylococcus aureus was the dominant pathogen in haematogenous PJI (76/140, 54%) and coagulase-negative staphylococci in non-haematogenous PJI (57/133, 43%). In both groups, multi-stage exchange (n = 55 (38%) in haematogenous and n = 73 (46%) in non-haematogenous PJI) and prosthesis retention (n = 70 (48%) in haematogenous and n = 48 (30%) in non-haematogenous PJI) were the most common surgical strategies. Median duration of antimicrobial treatment was 13.5 weeks (range, 0.5 to 218 weeks) and similar in both groups. After six years of follow-up, the probability of failure-free survival was significantly lower in haematogenous compared to non-haematogenous PJI (55% vs 74%; p = 0.021). Infection-related mortality was significantly higher in haematogenous than non-haematogenous PJI (7% vs 0% episodes; p = 0.001). Pathogenesis of failure was similar in both groups. Retention of the prosthesis was the only independent risk factor for failure in multivariate analysis in both groups. Conclusion. Treatment failure was significantly higher in haematogenous compared to non-haematogenous PJI. Retention of the prosthesis was the only independent risk factor for failure in both groups. Cite this article: Bone Joint J 2023;105-B(12):1294–1302

Meniscal repairs are commonly performed during anterior cruciate ligament (ACL) reconstruction. This study aimed to identify the risk factors for meniscal repair failure following concurrent primary ACL reconstruction. Primary ACL reconstructions with a concurrent repair of a meniscal tear recorded in the New Zealand ACL Registry between April 2014 and December 2018 were analyzed. Meniscal repair failure was defined as a patient who underwent subsequent meniscectomy, and was identified after cross-referencing data from the ACL Registry with the national database of the Accident Compensation Corporation (ACC). Multivariate Cox regression was performed to produce hazard ratios (HR) with 95% confidence intervals (CI) to identify the patient and surgical risk factors for meniscal repair failure. 2041 meniscal repairs were analyzed (medial = 1235 and lateral = 806). The overall failure rate was 9.4% (n = 192). Failure occurred in 11.1% of medial (137/1235) and 6.8% of lateral (55/806) meniscal repairs. The risk of medial failure was higher with hamstring tendon autografts (adjusted HR = 2.00, 95% CI 1.23 – 3.26, p = 0.006) and in patients with cartilage injury in the medial compartment (adjusted HR = 1.56, 95% CI 1.09 – 2.23, p = 0.015). The risk of lateral failure was higher when the procedure was performed by a surgeon with an annual case volume of less than 30 ACL reconstructions (adjusted HR = 1.92, 95% CI 1.10 – 3.33, p = 0.021). Age, gender, time from injury-to-surgery and femoral tunnel drilling technique did not influence the risk of meniscal repair failure. When repairing a meniscal tear during ACL reconstruction, the use of a hamstring tendon autograft or the presence of cartilage injury in the medial compartment increases the risk of medial meniscal repair failure. Lower surgeon case volume increases the risk of lateral meniscal repair failure

The Accolade®TMZF is a taper-wedge cementless metaphyseal coated femoral stem widely utilized from 2002-2012. In recent years, there have been reports of early catastrophic failure of this implant. Establishing a deeper understanding of the rate and causes of revision in patients who developed aseptic failure in stems with documented concerns about high failure rates is critical. Understanding any potential patient or implant factors which are risk factors for failure is important to inform both clinicians and patients. We propose a study to establish the long-term survival of this stem and analyze patients who underwent aseptic revision to understand the causes and risk factors for failure. A retrospective review was undertaken of all patients who received a primary total hip arthroplasty with an Accolade® TMZF stem at a high-volume arthroplasty center. The causes and timing of revision surgery were documented and cross referenced with the Canadian Institute of Health Information Discharge Abstract Database to minimize loss to follow-up. Survivorship analysis was performed with use of the Kaplan-Meier curves to determine the overall and aseptic survival rates at final follow-up. Patient and implant factors commonly associated with aseptic failure were extracted and Cox proportional hazards model was used. A consecutive series of 2609 unilateral primary THA patients implanted with an Accolade®TMZF femoral hip stem were included. Mean time from primary surgery was 12.4 years (range 22 days to 19.5 years). Cumulative survival was 96.1% ± 0.2 at final follow-up. One hundred and seven patients underwent revision surgery with aseptic loosening of the femoral component was the most common cause of aseptic failure in this cohort (33/2609, 1.3%). Younger age and larger femoral head offset were independent risk factors for aseptic failure. To our knowledge, this is the largest series representing the longest follow-up of this taper-wedge cementless femoral implant. Despite early concerns, the Accolade® TMZF stem has excellent survivorship in this cohort. Trunnionosis as a recognized cause for revision surgery was rare. Younger age and larger femoral head offset were independent risk factors for aseptic failure

Bone turnover and the accumulation of microdamage are impacted by the presence of skeletal metastases which can contribute to increased fracture risk. Treatments for metastatic disease may further impact bone quality. The present study aims to establish a preliminary understanding of microdamage accumulation and load to failure in osteolytic vertebrae following stereotactic body radiotherapy (SBRT), zoledronic acid (ZA), or docetaxel (DTX) treatment. Twenty-two six-week old athymic female rats (Hsd:RH-Foxn1rnu, Envigo, USA) were inoculated with HeLa cervical cancer cells through intracardiac injection (day 0). Institutional approval was obtained for this work and the ARRIVE guidelines were followed. Animals were randomly assigned to four groups: untreated (n=6), spine stereotactic body radiotherapy (SBRT) administered on day 14 (n=6), zoledronic acid (ZA) administered on day 7 (n=5), and docetaxel (DTX) administered on day 14 (n=5). Animals were euthanized on day 21. T13-L3 vertebral segments were collected immediately after sacrifice and stored in −20°C wrapped in saline soaked gauze until testing. µCT scans (µCT100, Scanco, Switzerland) of the T13-L3 segment confirmed tumour burden in all T13 and L2 vertebrae prior to testing. T13 was stained with BaSO. 4. to label microdamage. High resolution µCT scans were obtained (90kVp, 44uA, 4W, 4.9µm voxel size) to visualize stain location and volume. Segmentations of bone and BaSO. 4. were created using intensity thresholding at 3000HU (~736mgHA/cm. 3. ) and 10000HU (~2420mgHA/cm. 3. ), respectively. Non-specific BaSO. 4. was removed from the outer edge of the cortical shell by shrinking the segmentation by 105mm in 3D. Stain volume fraction was calculated as the ratio of BaSO. 4. volume to the sum of BaSO. 4. and bone volume. The L1-L3 motion segments were loaded under axial compression to failure using a µCT compatible loading device (Scanco) and force-displacement data was recorded. µCT scans were acquired unloaded, at 1500µm displacement and post-failure. Stereological analysis was performed on the L2 vertebrae in the unloaded µCT scans. Differences in mean stain volume fraction, mean load to failure, and mean bone volume/total volume (BV/TV) were compared between treatment groups using one-way ANOVAs. Pearson's correlation between stain volume fraction and load to failure by treatment was calculated using an adjusted load to failure divided by BV/TV. Stained damage fraction was significantly different between treatment groups (p=0.0029). Tukey post-hoc analysis showed untreated samples to have higher stain volume fraction (16.25±2.54%) than all treatment groups (p<0.05). The ZA group had the highest mean load to failure (195.60±84.49N), followed by untreated (142.33±53.08N), DTX (126.60±48.75N), and SBRT (95.50±44.96N), but differences did not reach significance (p=0.075). BV/TV was significantly higher in the ZA group (49.28±3.56%) compared to all others. The SBRT group had significantly lower BV/TV than the untreated group (p=0.018). Load divided by BV/TV was not significantly different between groups (p=0.24), but relative load to failure results were consistent (ZA>Untreated>DTX>SBRT). No correlations were found between stain volume fraction and load to failure. Focal and systemic cancer treatments effect microdamage accumulation and load to failure in osteolytic vertebrae. Current testing of healthy controls will help to further separate the effects of the tumour and cancer treatments on bone quality

Bone turnover and the accumulation of microdamage are impacted by the presence of skeletal metastases which can contribute to increased fracture risk. Treatments for metastatic disease may further impact bone quality. The present study aims to establish a preliminary understanding of microdamage accumulation and load to failure in osteolytic vertebrae following stereotactic body radiotherapy (SBRT), zoledronic acid (ZA), or docetaxel (DTX) treatment. Twenty-two six-week old athymic female rats (Hsd:RH-Foxn1rnu, Envigo, USA) were inoculated with HeLa cervical cancer cells through intracardiac injection (day 0). Institutional approval was obtained for this work and the ARRIVE guidelines were followed. Animals were randomly assigned to four groups: untreated (n=6), spine stereotactic body radiotherapy (SBRT) administered on day 14 (n=6), zoledronic acid (ZA) administered on day 7 (n=5), and docetaxel (DTX) administered on day 14 (n=5). Animals were euthanized on day 21. T13-L3 vertebral segments were collected immediately after sacrifice and stored in −20°C wrapped in saline soaked gauze until testing. µCT scans (µCT100, Scanco, Switzerland) of the T13-L3 segment confirmed tumour burden in all T13 and L2 vertebrae prior to testing. T13 was stained with BaSO. 4. to label microdamage. High resolution µCT scans were obtained (90kVp, 44uA, 4W, 4.9µm voxel size) to visualize stain location and volume. Segmentations of bone and BaSO. 4. were created using intensity thresholding at 3000HU (~736mgHA/cm. 3. ) and 10000HU (~2420mgHA/cm. 3. ), respectively. Non-specific BaSO. 4. was removed from the outer edge of the cortical shell by shrinking the segmentation by 105mm in 3D. Stain volume fraction was calculated as the ratio of BaSO. 4. volume to the sum of BaSO. 4. and bone volume. The L1-L3 motion segments were loaded under axial compression to failure using a µCT compatible loading device (Scanco) and force-displacement data was recorded. µCT scans were acquired unloaded, at 1500µm displacement and post-failure. Stereological analysis was performed on the L2 vertebrae in the unloaded µCT scans. Differences in mean stain volume fraction, mean load to failure, and mean bone volume/total volume (BV/TV) were compared between treatment groups using one-way ANOVAs. Pearson's correlation between stain volume fraction and load to failure by treatment was calculated using an adjusted load to failure divided by BV/TV. Stained damage fraction was significantly different between treatment groups (p=0.0029). Tukey post-hoc analysis showed untreated samples to have higher stain volume fraction (16.25±2.54%) than all treatment groups (p<0.05). The ZA group had the highest mean load to failure (195.60±84.49N), followed by untreated (142.33±53.08N), DTX (126.60±48.75N), and SBRT (95.50±44.96N), but differences did not reach significance (p=0.075). BV/TV was significantly higher in the ZA group (49.28±3.56%) compared to all others. The SBRT group had significantly lower BV/TV than the untreated group (p=0.018). Load divided by BV/TV was not significantly different between groups (p=0.24), but relative load to failure results were consistent (ZA>Untreated>DTX>SBRT). No correlations were found between stain volume fraction and load to failure. Focal and systemic cancer treatments effect microdamage accumulation and load to failure in osteolytic vertebrae. Current testing of healthy controls will help to further separate the effects of the tumour and cancer treatments on bone quality

Aim. Patients with late acute periprosthetic joint infections (PJI) and treated with surgical debridement have a high failure rate. Previous studies have shown that rheumatoid arthritis (RA) is an independent risk factor for treatment failure. We conducted a case-control study to identify predictors for failure in late acute PJI treatment in RA patients. We hypothesize that patients with RA have a higher failure rate compared to controls due to the use of immunosuppressive drugs. Method. Data of an international multicenter retrospective observational study was used. Late acute PJI was defined as a sudden onset of symptoms and signs of a PJI, more than 3 months after implantation. Failure of treatment was defined as persistent signs of infection, relapse with the same or reinfection with a different micro-organism, need for prosthesis removal or death. Cases with RA were matched with cases without RA based on the affected joint. A Cox survival analyses, stratified for RA, was used to calculate hazard ratio's (HR) for failure. Subgroup analyses were used to explore other predictors for treatment failure in RA patients. Results. A total of 40 patients with RA and 80 controls without RA were included. Treatment failure occurred in 65% patients with RA compared to 45% for controls (p= .052). 68% of patients with RA used immunosuppressive drugs at time of PJI diagnosis. The use or continuation of immunosuppressive drugs in PJI was not associated with a higher failure rate; neither were the duration of symptoms and causative microorganism. The time between implantation of the prosthetic joint and diagnosis of infection was longer in RA patients: median 110 (IQR 41-171) vs 29 months (IQR 7.5–101.25). Exchange of mobile components was associated with a lower risk of treatment failure (HR 0.489, 95% CI 0.242–0.989, p-value .047). Conclusions. The use of immunosuppressive drugs does not seem to be associated with a higher failure rate in patients with RA. Mobile exchange in RA patients is associated with a lower risk of failure. This might be due to the significantly older age of the prosthesis in RA patients. Future studies are needed to explore these associations and its underlying pathogenesis

Introduction. Surgical reconstruction of deformed Charcot feet carries high risk of non-union, metalwork failure and deformity recurrence. The primary aim of this study was to identify the factors contributing to these complications following hindfoot Charcot reconstructions. Methods. We retrospectively analysed patients who underwent hindfoot Charcot reconstruction with an intramedullary nail between 2007 and 2019 in our unit. Patient demographics, co-morbidities, weightbearing status and post-operative complications were noted. Metalwork breakage, non-union, deformity recurrence, concurrent midfoot reconstruction and the measurements related to intramedullary nail were also recorded. Results. There were 70 patients with mean follow up of 50±26 months. Seventy-two percent were fully weightbearing at 1 year post-operatively. The overall union rate was 83%. Age, BMI, HbA1c and peripheral vascular disease did not affect union. The ratio of nail diameter and isthmus was greater in the united compared to the non-united group (0.90±0.06 and 0.86±0.09, respectively; p = 0.03). Supplemental compression devices were used for 33% of those in the united compared to 8% in the non-united group (p = 0.04). All patients in the non-union group did not have a miss-a-nail screw. Metalwork failure was seen in 13 patients(19%). There was a significantly greater distal screw metalwork failure in those with supplementary bridging of tibia to midfoot (23% vs. 3%; p = 0.001). An intact medial malleolus was found more frequently in those with intact metalwork (77% vs. 54%, respectively; p = 0.02) and those with union (76% vs. 50%; p = 0.02). Broken metalwork occurred more frequently in patients with non-unions (69% vs. 8%; p < 0.001) and deformity recurrence (69% vs. 9%; p < 0.001). Conclusion. Satisfactory clinical and radiographic outcomes occur in over 80% of patients. Union after hindfoot reconstruction occurs more frequently with an isthmic fit of the intramedullary nail, supplementary compression and miss-a-nail screws. An intact medial malleolus is protective against non-union and metalwork failure. Broken metalwork is linked to deformity recurrence and non-union

Aim. The most frequent mechanical failure in the osteosynthesis of intertrochanteric fractures is the cut-out. Fracture pattern, reduction quality, tip-apex distance or the position of the cervico-cephalic screw are some of the factors that have been associated with higher cut-out rates. To date, it has not been established whether underlying bacterial colonization or concomitant infection may be the cause of osteosynthesis failure in proximal femur fractures (PFF). The primary objective of this study is to assess the incidence of infection in patients with cut-out after PFF osteosynthesis. Method. Retrospective cohort study on patients with cut-out after PFF osteosynthesis with endomedullary nail, from January 2007 to December 2020. Demographic data of patients (such as sex, age, ASA), fracture characteristics (pattern, laterality, causal mechanism) and initial surgery parameters were collected (time from fall to intervention, duration of surgery, intraoperative complications). Radiographic parameters were also analyzed (tip-apex distance and Chang criteria). In all cut-out cases, 5 microbiological cultures and 1 anatomopathological sample were taken and the osteosynthesis material was sent for sonication. Fracture-related infection (FRI) was diagnosed based on Metsemakers et al (2018) and McNally et al (2020) diagnostic criteria. Results. Of the 67 cut-out cases, 16 (23.9%) presented clinical, analytical or microbiological criteria of infection. Of these sixteen patients, only in 3 of them the presence of an underlying infection was suspected preoperatively. A new osteosynthesis was performed in 24 cases (35.8%) and a conversion to arthroplasty in the remaining 43 (64.2%). A comparative analysis was performed between cases with and without infection. The groups were comparable in terms of demographic data and postoperative radiological data (using Chang criteria and tip-apex distance). Patients with underlying infection had a higher rate of surgical wound complication (56.3% vs 22%, p = 0.014), higher rates of leukocytes counts (11.560 vs 7.890, p = 0.023) and time to surgery (5.88 vs 3.88 days, p = 0.072). Conclusions. One out of four osteosynthesis failure in PFF is due to underlying FRI and in almost 20% were not unsuspected before surgery. In PFF osteosynthesis failures, underlying infection should be taken into account as a possible etiological factor and thus a preoperative and intraoperative infection study should be always performed

Introduction. Debridement, antibiotics irrigation and implant retention (DAIR) is a common management strategy for hip and knee prosthetic joint infections (PJI). However, failure rates remain high, which has led to the development of predictive tools to help determine success. These tools include KLIC and CRIME80 for acute-postoperative (AP) and acute haematogenous (AH) PJI respectively. We investigated whether these tools were applicable to a Waikato cohort. Method. We performed a retrospective cohort study that evaluated patients who underwent DAIR between January 2010 and June 2020 at Waikato Hospital. Pre-operative KLIC and CRIME80 scores were calculated and compared to success of operation. Failure was defined as: (i) need for further surgery, (ii) need for suppressive antibiotics, (iii) death due to the infection. Logistic regression models were used to calculate the area under the curve (AUC). Results. 117 eligible patients underwent DAIR, 53 in the AP cohort and 64 in the AH cohort. Failure rate at 2 years post-op was 43% in the AP cohort and 59% in the AH cohort. In the AP cohort a KLIC score of <4 had a DAIR failure rate of 28.6%, while those who scored ³4 had a failure rate of 72.2% (p=0.002). In the AH cohort a CRIME80 score of <3 had a DAIR failure rate of 48% while those who scored ³3 had a 100% failure rate (p<0.001). Discussion. This study represents the first external validation of the KLIC and CRIME80 scores for predicting DAIR failure in an Australasian population. The results indicate that both KLIC and CRIME80 scoring tools are valuable aids for the clinician seeking to determine the optimal management strategy in patients with AP or AH PJI

Fracture related infections (FRI) are debilitating complications of musculoskeletal trauma surgery that can result in permanent functional loss or amputation. This study aims to determine risk factors associated with FRI treatment failure, allowing clinicians to optimise them prior to treatment and identify patients at higher risk. A major trauma centre database was retrospectively reviewed over a six-year period. Of the 102 patients identified with a FRI (66 male, 36 female), 29.4% (n=30) had acute infections (onset <6 weeks post-injury), 34.3% (n=35) had an open fracture. Open fractures were classified using Gustilo-Anderson (GA) classification (type 2:n=6, type 3A:n=16, type 3B:n=10, type 3C:n=3). Patients with periprosthetic infections of the hip and knee joint, those without prior fracture fixation, soft tissue infections, diabetic foot ulcers, pressure sore infections, patients who died within one month of injury, <12 months follow-up were excluded. FRI treatment failure was defined as either infection recurrence, non-union, or amputation. Lifestyle, clinical, and intra-operative data were documented via retrospective review of medical records. Factors with a P-value of p<0.05 in univariate analysis were included in a stepwise multivariate logistic regression model. FRI treatment failure was encountered in 35.3% (n=36). The most common FRI site was the femoral shaft (16.7%; n=17), and 15.7% (n=16) presented with signs of systemic sepsis. 20.6% (n=21) had recurrent infection, 9.8% (n=10) had non-union, and 4.9% (n=5) required an amputation. The mean age at injury was 49.71 years old. Regarding cardiovascular risk factors, 37 patients were current smokers (36.3%), 31 patients were diabetics (30.4%), and 32 patients (31.4%) were obese (BMI≥30.0). Average follow-up time was 2.37 (range: 1.04-5.14) years. Risk factors for FRI treatment failure were BMI>30, GA type 3c, and implant retention. Given that FRI treatment in 35.3% (36/102) ended up in failure, clinicians need to take into account the predictive variables analysed in this study, and implement a multidisciplinary team approach to optimise these factors. This study could aid clinicians to redirect efforts to improve high risk patient management, and prompt future studies to trial adjuvant technologies for patients at higher risk of failure