Aims. The primary objective of this study was to develop a validated classification system for assessing iatrogenic bone trauma and soft-tissue injury during total hip arthroplasty (THA). The secondary objective was to compare macroscopic bone trauma and soft-tissues injury in conventional THA (CO THA) versus robotic arm-assisted THA (RO THA) using this classification system. Methods. This study included 30 CO THAs versus 30 RO THAs performed by a single surgeon. Intraoperative photographs of the osseous acetabulum and periacetabular soft-tissues were obtained prior to implantation of the acetabular component, which were used to develop the proposed classification system. Interobserver and intraobserver variabilities of the proposed classification system were assessed. Results. The BOne trauma and Soft-Tissue Injury classification system in total Hip arthroplasty (BOSTI Hip) grades osseous acetabular trauma and periarticular muscle damage during THA. The classification system has an interclass correlation coefficient of 0.90 (95% CI 0.86 to 0.93) for interobserver agreement and 0.89 (95% CI 0.84 to 0.93) for intraobserver agreement. RO THA was associated with improved BOSTI Hip scores (p = 0.002) and more pristine osseous surfaces in the anterior superior (p = 0.001) and posterior superior (p < 0.001) acetabular quadrants compared with CO THA. There were no differences between the groups in relation to injury to the gluteus medius (p = 0.084), obturator internus (p = 0.241), piriformis (p = 0.081), superior gamellus (p = 0.116), inferior gamellus (p = 0.132), quadratus femoris (p = 0.208), and vastus lateralis (p = 0.135), but overall combined muscle injury was reduced in RO THA compared with CO THA (p = 0.023). Discussion. The proposed BOSTI Hip classification provides a reproducible grading system for stratifying iatrogenic bone trauma and soft-tissue injury during THA. RO THA was associated with improved BOSTI Hip scores, more pristine osseous acetabular surfaces, and reduced combined periarticular muscle injury compared with CO THA. Further research is required to understand if these intraoperative findings translate to differences in clinical outcomes between the treatment groups. Cite this article: Bone Joint J 2024;106-B(9):898–906

Aims. Our objective was describing an algorithm to identify and prevent vascular injury in patients with intrapelvic components. Methods. Patients were defined as at risk to vascular injuries when components or cement migrated 5 mm or more beyond the ilioischial line in any of the pelvic incidences (anteroposterior and Judet view). In those patients, a serial investigation was initiated by a CT angiography, followed by a vascular surgeon evaluation. The investigation proceeded if necessary. The main goal was to assure a safe tissue plane between the hardware and the vessels. Results. In ten at-risk patients undergoing revision hip arthroplasty and submitted to our algorithm, six were recognized as being high risk to vascular injury during surgery. In those six high-risk patients, a preventive preoperative stent was implanted before the orthopaedic procedure. Four patients needed a second reinforcing stent to protect and to maintain the vessel anatomy deformed by the intrapelvic implants. Conclusion. The evaluation algorithm was useful to avoid blood vessels injury during revision total hip arthroplasty in high-risk patients. Cite this article: Bone Jt Open 2022;3(11):859–866

Aims. Lateral femoral cutaneous nerve (LFCN) injury is a potential complication after the direct anterior approach for total hip arthroplasty (DAA-THA). The aim of this study was to determine how the location of the fasciotomy in DAA-THA affects LFCN injury. Methods. In this trial, 134 patients were randomized into a lateral fasciotomy (n = 67) or a conventional fasciotomy (n = 67) group. This study was a dual-centre, double-blind, prospective randomized controlled two-arm trial with parallel group design and a 1:1 allocation ratio. The primary endpoint was the presence of LFCN injury, which was determined by the presence of numbness, decreased sensation, tingling, jolt-like sensation, or pain over the lateral aspect of the thigh, excluding the surgical scar, using a patient-based questionnaire. The secondary endpoints were patient-reported outcome measures (PROMs) using the Western Ontario and McMaster Universities osteoarthritis index (WOMAC), Japanese Orthopaedic Association Hip Disease Evaluation Questionnaire (JHEQ), and the Forgotten Joint Score-12 (FJS-12). Assessments were obtained three months after surgery. Results. The incidence of LFCN injury tended to be lower in the lateral fasciotomy group (p = 0.089). In the lateral fasciotomy group, there were no significant differences in the mean PROM scores between patients with and without LFCN injury (FJS-12: 54.42 (SD 15.77) vs 65.06 (SD 26.14); p = 0.074; JHEQ: 55.21 (SD 12.10) vs 59.72 (SD 16.50); p = 0.288; WOMAC: 82.45 (SD 6.84) vs 84.40 (SD 17.91); p = 0.728). In the conventional fasciotomy group, there were significant differences in FJS-12 and JHEQ between patients with and without LFCN injury (FJS-12: 43.21 (SD 23.08) vs 67.28 (SD 20.47); p < 0.001; JHEQ: 49.52 (SD 13.97) vs 59.59 (SD 15.18); p = 0.012); however, there was no significant difference in WOMAC (76.63 (SD 16.81) vs 84.16 (SD 15.94); p = 0.107). Conclusion. The incidence of LFCN injury at three months after THA was comparable between the lateral and conventional fasciotomy groups. Further studies are needed to assess the long-term effects of these approaches. Cite this article: Bone Joint J 2023;105-B(12):1252–1258

Aims. Injury to the lateral femoral cutaneous nerve (LFCN) is one of the known complications after periacetabular osteotomy (PAO) performed using the anterior approach, reported to occur in between 1.5% and 65% of cases. In this study, we performed a prospective study on the incidence of LFCN injury as well as its clinical outcomes based on the Harris Hip Score (HHS), Short-Form 36 Health Survey (SF-36), and Japanese Orthopaedic Association Hip Disease Evaluation Questionnaire (JHEQ). Methods. The study included 42 consecutive hips in 42 patients (three male and 39 female) who underwent PAO from May 2016 to July 2018. We prospectively evaluated the incidence of LFCN injury at ten days, three months, six months, and one year postoperatively. We also evaluated the clinical scores, including the HHS, SF-36, and JHEQ scores, at one year postoperatively. Results. LFCN injury was observed in 31 of 42 (74%) patients at ten days, of which 11 resolved completely by one year. Incidence decreased gradually, to 25 of 42 (60%) patients at three months, 24 of 42 patients (57%) at six months, and 20 of 42 (48%) patients at one year postoperatively. There was no significant difference in the HHS between patients with and without LFCN injury at one year postoperatively. Regarding the SF-36 and JHEQ, a significant difference in the mental score was recognized between patients with and without LFCN injury, but there were no significant differences in the other clinical scores. Conclusion. The incidence of LFCN injury was 74% at ten days after PAO, and subsequently decreased to 48% at one year. LFCN injury did not influence the hip function as assessed by the HHS, but had a negative impact on mental health at one year. Cite this article: Bone Joint J 2021;103-B(4):659–664

Vascular injuries during total hip arthroplasty (THA) are rare but when they occur, have serious consequences. These have traditionally been managed with open exploration and repair, but more recently there has been a trend towards percutaneous endovascular management. We performed a systematic review of the literature to assess if this change in trend has led to an improvement in the overall reported rates of morbidity and mortality during the last 22 years in comparison with the reviews of the literature published previously. . We found a total of 61 articles describing 138 vascular injuries in 124 patients. Injuries because of a laceration were the most prevalent (n = 51, 44%) and the most common presenting feature, when recorded, was bleeding (n = 41, 53.3%). Delay in diagnosis was associated with the type of vascular lesion (p < 0.001) and the clinical presentation (p = 0.002). Open exploration and repair was the most common form of management, however percutaneous endovascular intervention was used in one third of the injuries and more constantly during the last 13 years. The main overall reported complications included death (n = 9, 7.3%), amputation (n = 2, 1.6%), and persistent ischaemia (n = 9, 7.3%). When compared with previous reviews there was a similar rate of mortality but lower rates of amputation and permanent disability, especially in patients managed by endovascular strategies. Cite this article: Bone Joint J 2015;97-B:1447–55

The modified Smith–Petersen and Kocher–Langenbeck approaches were used to expose the lateral cutaneous nerve of the thigh and the femoral, obturator and sciatic nerves in order to study the risk of injury to these structures during the dissection, osteotomy, and acetabular reorientation stages of a Bernese peri-acetabular osteotomy. Injury of the lateral cutaneous nerve of thigh was less likely to occur if an osteotomy of the anterior superior iliac spine had been carried out before exposing the hip. The obturator nerve was likely to be injured during unprotected osteotomy of the pubis if the far cortex was penetrated by > 5 mm. This could be avoided by inclining the osteotome 45° medially and performing the osteotomy at least 2 cm medial to the iliopectineal eminence. . The sciatic nerve could be injured during the first and last stages of the osteotomy if the osteotome perforated the lateral cortex of ischium and the ilio-ischial junction by > 10 mm. The femoral nerve could be stretched or entrapped during osteotomy of the pubis if there was significant rotational or linear displacement of the acetabulum. Anterior or medial displacement of < 2 cm and lateral tilt (retroversion) of < 30° were safe margins. The combination of retroversion and anterior displacement could increase tension on the nerve. Strict observation of anatomical details, proper handling of the osteotomes and careful manipulation of the acetabular fragment reduce the neurological complications of Bernese peri-acetabular osteotomy. Cite this article: Bone Joint J 2015;97-B:636–41

Peripheral nerve injury is an uncommon but serious complication of hip surgery that can adversely affect the outcome. Several studies have described the use of electromyography and intra-operative sensory evoked potentials for early warning of nerve injury. We assessed the results of multimodal intra-operative monitoring during complex hip surgery. We retrospectively analysed data collected between 2001 and 2010 from 69 patients who underwent complex hip surgery by a single surgeon using multimodal intra-operative monitoring from a total pool of 7894 patients who underwent hip surgery during this period. In 24 (35%) procedures the surgeon was alerted to a possible lesion to the sciatic and/or femoral nerve. Alerts were observed most frequently during peri-acetabular osteotomy. The surgeon adapted his approach based on interpretation of the neurophysiological changes. From 69 monitored surgical procedures, there was only one true positive case of post-operative nerve injury. There were no false positives or false negatives, and the remaining 68 cases were all true negative. The sensitivity for predicting post-operative nerve injury was 100% and the specificity 100%. We conclude that it is possible and appropriate to use this method during complex hip surgery and it is effective for alerting the surgeon to the possibility of nerve injury

In this paper we propose a new classification of neurogenic peri-articular heterotopic ossification (HO) of the hip based on three-dimensional (3D) CT, with the aim of improving pre-operative planning for its excision. . A total of 55 patients (73 hips) with clinically significant HO after either traumatic brain or spinal cord injury were assessed by 3D-CT scanning, and the results compared with the intra-operative findings. At operation, the gross pathological anatomy of the HO as identified by 3D-CT imaging was confirmed as affecting the peri-articular hip muscles to a greater or lesser extent. We identified seven patterns of involvement: four basic (anterior, medial, posterior and lateral) and three mixed (anteromedial, posterolateral and circumferential). Excellent intra- and inter-observer agreement, with kappa values > 0.8, confirmed the reproducibility of the classification system. We describe the different surgical approaches used to excise the HO which were guided by the 3D-CT findings. Resection was always successful. . 3D-CT imaging, complemented in some cases by angiography, allows the surgeon to define the 3D anatomy of the HO accurately and to plan its surgical excision with precision. Cite this article: Bone Joint J 2015; 97-B:899–904

Nerve injury is a rare complication of total hip replacement which may be related to the exposure used for the operation. The posterior approach is traditionally associated with injury to the sciatic nerve. We have compared the incidence of nerve injury after primary total hip replacement (THR) using either a posterior or a direct lateral approach. We studied 42 consecutive patients undergoing primary total hip replacement. The surgeons used a posterior (22 patients) or direct lateral (20 patients) approach in accordance with their normal practice. The obturator, femoral, posterior tibial and common peroneal nerves were assessed clinically and electrophysiologically by electromyography (EMG) and measurement of the velocity of nerve conduction before operation and at four weeks after. All patients were free from symptoms of nerve injury after operation but five lesions were identified in four patients by the electrophysiological studies; the obturator nerve was involved in two, the femoral in one, the common peroneal in one and the posterior tibial in one. All these injuries occurred using the lateral approach. Clinical assessment alone underestimates the incidence of nerve injury complicating THR. Our study does not confirm the association of nerve injury with the posterior approach which had been described previously

Aims. To describe the epidemiology of acetabular fractures including patient characteristics, injury mechanisms, fracture patterns, treatment, and mortality. Methods. We retrieved information from the Swedish Fracture Register (SFR) on all patients with acetabular fractures, of the native hip joint in the adult skeleton, sustained between 2014 and 2020. Study variables included patient age, sex, injury date, injury mechanism, fracture classification, treatment, and mortality. Results. In total, 2,132 patients with acetabular fractures from the SFR were included in the study. The majority of the patients were male (62%) and aged over 70 years old (62%). For patients aged > 70 years, the 30-day mortality was 8% and one-year mortality 24%. For patients aged ≤ 70 years, the 30-day mortality was 0.2% and one-year mortality 2%. Low-energy injuries (63%) and anterior wall fractures (20%) were most common. Treatment was most often non-surgical (75%). Conclusion. The majority of patients who sustain an acetabular fracture are elderly (> 70 years), of male sex, and the fracture most commonly occurs after a simple, low-energy fall. Non-surgical treatment is chosen in the majority of acetabular fracture patients. The one-year mortality for elderly patients with acetabular fracture is similar to the mortality after hip fracture, and a similar multidisciplinary approach to care for these patients should be considered. Cite this article: Bone Jt Open 2023;4(9):652–658

Aims. Periprosthetic proximal femoral fractures (PFFs) are a major complication after total hip arthroplasty (THA). Health status after PFF is not specifically investigated. The aim of this study is to evaluate the health status pattern over two years after sustaining a PFF. Methods. A cohort of patients with PFF after THA was derived from the Brabant Injury Outcomes Surveillance (BIOS) study. The BIOS study, a prospective, observational, multicentre follow-up cohort study, was conducted to obtain data by questionnaires pre-injury and at one week, and one, three, six, 12, and 24 months after trauma. Primary outcome measures were the EuroQol five-dimension three-level questionnaire (EQ-5D-3L), the Health Utility Index 2 (HUI2), and the Health Utility Index 3 (HUI3). Secondary outcome measures were general measurements such as duration of hospital stay and mortality. Results. A total of 70 patients with a PFF were included. EQ-5D utility scores were significantly lower on all timepoints except at six months’ follow-up compared to pre-injury. EuroQol visual analogue scale (EQ-VAS) scores at one month's follow-up were significantly lower compared to pre-injury. The percentage of reported problems at two years was higher for all dimensions except anxiety/depression when compared to pre-injury. The mean EQ-5D utility score was 0.26 higher in males compared to females (95% confidence interval (CI) 0.01 to 0.42; p = 0.003). The mean EQ-VAS score for males was 8.9 points higher when compared to females over all timepoints (95% CI 1.2 to 16.7; p = 0.027). Mortality was 10% after two years’ follow-up. Conclusion. PFF patients are a frail population with substantial functional impairment at baseline. Post-injury, they have a significant and clinically relevant lower health status two years after trauma when compared to pre-injury. Health status improves the most between one and three months after injury. Two years after PFF, more patients experience problems in mobility, self-care, usual activities, and pain/discomfort than pre-injury. Cite this article: Bone Joint J 2024;106-B(5):442–449

Aims. Our primary aim was to assess reoperation-free survival at one year after the index injury in patients aged ≥ 75 years treated with internal fixation (IF) or arthroplasty for undisplaced femoral neck fractures (uFNFs). Secondary outcomes were reoperations and mortality analyzed separately. Methods. We retrieved data on all patients aged ≥ 75 years with an uFNF registered in the Swedish Fracture Register from 2011 to 2018. The database was linked to the Swedish Arthroplasty Register and the National Patient Register to obtain information on comorbidity, mortality, and reoperations. Our primary outcome, reoperation, or death at one year was analyzed using restricted mean survival time, which gives the mean time to either event for each group separately. Results. Overall, 3,909 patients presenting with uFNFs were included. Of these patients, 3,604 were treated with IF and 305 with primary arthroplasty. There were no relevant differences in age, sex, or comorbidities between groups. In the IF group 58% received cannulated screws and 39% hook pins. In the arthroplasty group 81% were treated with hemiarthroplasty and 19% with total hip arthroplasty. At one year, 32% were dead or had been reoperated in both groups. The reoperation-free survival time over one year of follow-up was 288 days (95% confidence interval (CI) 284 to 292) in the IF group and 279 days (95% CI 264 to 295) in the arthroplasty group, with p = 0.305 for the difference. Mortality was 26% in the IF group and 31% in the arthroplasty group at one year. Reoperation rates were 7.1% in the IF group and 2.3% in the arthroplasty group. Conclusion. In older patients with a uFNF, reoperation-free survival at one year seems similar, regardless of whether IF or arthroplasty is the primary surgery. However, this comparison depends on the choice of follow-up time in that reoperations were more common after IF. In contrast, we found more early deaths after arthroplasty. Our study calls for a randomized trial comparing these two methods. Cite this article: Bone Jt Open 2024;5(2):86–92

Aims. To develop prediction models using machine-learning (ML) algorithms for 90-day and one-year mortality prediction in femoral neck fracture (FNF) patients aged 50 years or older based on the Hip fracture Evaluation with Alternatives of Total Hip arthroplasty versus Hemiarthroplasty (HEALTH) and Fixation using Alternative Implants for the Treatment of Hip fractures (FAITH) trials. Methods. This study included 2,388 patients from the HEALTH and FAITH trials, with 90-day and one-year mortality proportions of 3.0% (71/2,388) and 6.4% (153/2,388), respectively. The mean age was 75.9 years (SD 10.8) and 65.9% of patients (1,574/2,388) were female. The algorithms included patient and injury characteristics. Six algorithms were developed, internally validated and evaluated across discrimination (c-statistic; discriminative ability between those with risk of mortality and those without), calibration (observed outcome compared to the predicted probability), and the Brier score (composite of discrimination and calibration). Results. The developed algorithms distinguished between patients at high and low risk for 90-day and one-year mortality. The penalized logistic regression algorithm had the best performance metrics for both 90-day (c-statistic 0.80, calibration slope 0.95, calibration intercept -0.06, and Brier score 0.039) and one-year (c-statistic 0.76, calibration slope 0.86, calibration intercept -0.20, and Brier score 0.074) mortality prediction in the hold-out set. Conclusion. Using high-quality data, the ML-based prediction models accurately predicted 90-day and one-year mortality in patients aged 50 years or older with a FNF. The final models must be externally validated to assess generalizability to other populations, and prospectively evaluated in the process of shared decision-making. Cite this article: Bone Jt Open 2023;4(3):168–181

Aims. The aim of this study was to examine the implant accuracy of custom-made partial pelvis replacements (PPRs) in revision total hip arthroplasty (rTHA). Custom-made implants offer an option to achieve a reconstruction in cases with severe acetabular bone loss. By analyzing implant deviation in CT and radiograph imaging and correlating early clinical complications, we aimed to optimize the usage of custom-made implants. Methods. A consecutive series of 45 (2014 to 2019) PPRs for Paprosky III defects at rTHA were analyzed comparing the preoperative planning CT scans used to manufacture the implants with postoperative CT scans and radiographs. The anteversion (AV), inclination (IC), deviation from the preoperatively planned implant position, and deviation of the centre of rotation (COR) were explored. Early postoperative complications were recorded, and factors for malpositioning were sought. The mean follow-up was 30 months (SD 19; 6 to 74), with four patients lost to follow-up. Results. Mean CT defined discrepancy (Δ) between planned and achieved AV and IC was 4.5° (SD 3°; 0° to 12°) and 4° (SD 3.5°; 1° to 12°), respectively. Malpositioning (Δ > 10°) occurred in five hips (10.6%). Native COR reconstruction was planned in 42 cases (93%), and the mean 3D deviation vector was 15.5 mm (SD 8.5; 4 to 35). There was no significant influence in malpositioning found for femoral stem retention, surgical approach, or fixation method. Conclusion. At short-term follow-up, we found that PPR offers a viable solution for rTHA in cases with massive acetabular bone loss, as highly accurate positioning can be accomplished with meticulous planning, achieving anatomical reconstruction. Accuracy of achieved placement contributed to reduced complications with no injury to vital structures by screw fixation. Cite this article: Bone Joint J 2022;104-B(10):1110–1117

Aims. The aim of this study was to explore the functional results in a fitter subgroup of participants in the Hip Fracture Evaluation with Alternatives of Total Hip Arthroplasty versus Hemiarthroplasty (HEALTH) trial to determine whether there was an advantage of total hip arthroplasty (THA) versus hemiarthroplasty (HA) in this population. Methods. We performed a post hoc exploratory analysis of a fitter cohort of patients from the HEALTH trial. Participants were aged over 50 years and had sustained a low-energy displaced femoral neck fracture (FNF). The fittest participant cohort was defined as participants aged 70 years or younger, classified as American Society of Anesthesiologists grade I or II, independent walkers prior to fracture, and living at home prior to fracture. Multilevel models were used to estimate the effect of THA versus HA on functional outcomes. In addition, a sensitivity analysis of the definition of the fittest participant cohort was performed. Results. There were 143 patients included in the fittest cohort. Mean age was 66 years (SD 4.5) and 103 were female (72%). No clinically relevant differences were found between the treatment groups in the primary and sensitivity analyses. Conclusion. This analysis found no differences in functional outcomes between HA and THA within two years of displaced low-energy FNF in a subgroup analysis of the fittest HEALTH patients. These findings suggest that very few patients above 50 years of age benefit in a clinically meaningful way from a THA versus a HA early after injury. Cite this article: Bone Jt Open 2022;3(8):611–617

Aims. The aim of the HIPGEN consortium is to develop the first cell therapy product for hip fracture patients using PLacental-eXpanded (PLX-PAD) stromal cells. Methods. HIPGEN is a multicentre, multinational, randomized, double-blind, placebo-controlled trial. A total of 240 patients aged 60 to 90 years with low-energy femoral neck fractures (FNF) will be allocated to two arms and receive an intramuscular injection of either 150 × 10. 6. PLX-PAD cells or placebo into the medial gluteal muscle after direct lateral implantation of total or hemi hip arthroplasty. Patients will be followed for two years. The primary endpoint is the Short Physical Performance Battery (SPPB) at week 26. Secondary and exploratory endpoints include morphological parameters (lean body mass), functional parameters (abduction and handgrip strength, symmetry in gait, weightbearing), all-cause mortality rate and patient-reported outcome measures (Lower Limb Measure, EuroQol five-dimension questionnaire). Immunological biomarker and in vitro studies will be performed to analyze the PLX-PAD mechanism of action. A sample size of 240 subjects was calculated providing 88% power for the detection of a 1 SPPB point treatment effect for a two-sided test with an α level of 5%. Conclusion. The HIPGEN study assesses the efficacy, safety, and tolerability of intramuscular PLX-PAD administration for the treatment of muscle injury following arthroplasty for hip fracture. It is the first phase III study to investigate the effect of an allogeneic cell therapy on improved mobilization after hip fracture, an aspect which is in sore need of addressing for the improvement in standard of care treatment for patients with FNF. Cite this article: Bone Jt Open 2022;3(4):340–347

Aims. In UK there are around 76,000 hip fractures occur each year 10% to 15% of which are undisplaced intracapsular. There is considerable debate whether internal fixation is the most appropriate treatment for undisplaced fractures in older patients. This study describes cannulated hip screws survivorship analysis for patients aged ≥ 60 years with undisplaced intra-capsular fractures. Methods. This was a retrospective cohort study of consecutive patients aged ≥ 60 years who had cannulated screws fixation for Garden I and II fractures in a teaching hospital between March 2013 and March 2016. The primary outcome was further same-side hip surgery. Descriptive statistics were used and Kaplan-Meier estimates calculated for implant survival. Results. A total of 114 operations were performed on 112 patients with a mean age of 80.2 years (SD 8.9). The 30-day and one-year mortality were 1% (n = 1) and 13% (n = 15), respectively. Median follow-up was 6.6 years (interquartile range 6.0 to 7.3). Kaplan-Meier estimates showed a survivorship of 95% at one year and 90% at five years (95% confidence interval 84% to 95%) for cannulated screws. Nine patients underwent further hip surgery: four revision to total hip arthroplasty, one revision to hemiarthroplasty, three removals of screws, and one haematoma washout. Posterior tilt was assessable in 106 patients; subsequent surgery was required in two of the six patients identified with a posterior angle > 20° (p = 0.035 vs angle < 20°). Of the 100 patients with angle < 20°, five-year survivorship was 91%, with seven patients requiring further surgery. Conclusion. This study of cannulated hip screw fixation for undisplaced fractures in patients aged ≥ 60 years reveals a construct survivorship without further operation of 90% at five years. Cannulated screws can be considered a safe reliable treatment option for Garden I and II fractures. Caution should be taken if posterior tilt angle on lateral view exceeds 20°, due to a higher failure rate and reoperation, and considered for similar management to Garden III and IV injuries. Cite this article: Bone Jt Open 2022;3(3):182–188

Aims. This study assessed the impact of COVID-19 on hip and distal femur fracture patient outcomes across three successive UK lockdown periods over one year. Methods. A single-centre retrospective cohort study was performed at an acute NHS Trust. Hip and distal femur fracture patients admitted within the first month from each of the three starting dates of each national lockdown were included and compared to a control group in March 2019. Data were collected as per the best practice tariff outcomes including additional outcomes as required. Data collection included COVID-19 status, time to theatre, 30-day mortality, presence of acute kidney injury (AKI) and pneumonia, and do not attempt cardiopulmonary resuscitation (DNACPR) status. Data were analyzed using an independent-samples t-test or chi-squared test with Fisher’s exact test where applicable. A p-value of < 0.05 was considered statistically significant. Results. A total of 95 patients during the pandemic were included and 20 were COVID-positive. Patients experienced a statistically significant increase in time to theatre in Lockdown 1 compared to 2019 (p = 0.039) with a decrease with successive lockdown periods by Lockdown 3. The 30-day mortality increased from 8.8% in 2019 to 10.0% to 14.8% in all lockdown periods. COVID-positive patient mortality was 30.0% (p = 0.063, odds ratio (OR) = 4.43 vs 2019). The rates of AKI and pneumonia experienced were higher for patients during the pandemic. The highest rates were experienced in COVID-positive patients, with 45.0% of patients with AKI versus 27.0% in 2019 (p = 0.38, OR = 1.80), and 50.0% of patients diagnosed with pneumonia versus 16.2% in 2019 (p = 0.0012, OR = 5.17). The percentage of patients with a DNACPR increased from 30.0% in 2019 to 60.7% by Lockdown 3 (p = 0.034, OR = 3.61). Conclusion. COVID-positive hip and distal femur fracture patients are at a higher risk of mortality due to AKI and pneumonia. Patient outcomes have improved with successive lockdowns to pre-pandemic levels. Cite this article: Bone Jt Open 2021;2(12):1017–1026

Aims. This study aimed to explore whether intraoperative nerve monitoring can identify risk factors and reduce the incidence of nerve injury in patients with high-riding developmental dysplasia. Patients and Methods. We conducted a historical controlled study of patients with unilateral Crowe IV developmental dysplasia of the hip (DDH). Between October 2016 and October 2017, intraoperative nerve monitoring of the femoral and sciatic nerves was applied in total hip arthroplasty (THA). A neuromonitoring technician was employed to monitor nerve function and inform the surgeon of ongoing changes in a timely manner. Patients who did not have intraoperative nerve monitoring between September 2015 and October 2016 were selected as the control group. All the surgeries were performed by one surgeon. Demographics and clinical data were analyzed. A total of 35 patients in the monitoring group (ten male, 25 female; mean age 37.1 years (20 to 46)) and 56 patients in the control group (13 male, 43 female; mean age 37.9 years (23 to 52)) were enrolled. The mean follow-up of all patients was 13.1 months (10 to 15). Results. The two groups had no significant differences in preoperative data. In the monitoring group, ten nerve alerts occurred intraoperatively, and no neural complications were detected postoperatively. In the control group, six patients had neural complications. The rate of nerve injury was lower in the monitoring group than in the control group, but this did not achieve statistical significance. The degree of leg lengthening was significantly greater in the monitoring group than in the control group. In further analyses, patients who had previous hip surgery were more likely to have intraoperative nerve alerts and postoperative nerve injury. Conclusion. Nerve injury usually occurred during the processes of exposure and reduction. The use of intraoperative nerve monitoring showed a trend towards reduced nerve injury in THA for Crowe IV DDH patients. Hence, we recommend its routine use in patients undergoing leg lengthening, especially in those with previous hip surgery. Cite this article: Bone Joint J 2019;101-B:1438–1446

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