Aims

Early large treatment effects can arise in small studies, which lessen as more data accumulate. This study aimed to retrospectively examine whether early treatment effects occurred for two multicentre orthopaedic randomized controlled trials (RCTs) and explore biases related to this.

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The Ponseti method is the gold standard treatment for congenital talipes equinovarus (CTEV), with the British Consensus Statement providing a benchmark for standard of care. Meeting these standards and providing expert care while maintaining geographical accessibility can pose a service delivery challenge. A novel ‘Hub and Spoke’ Shared Care model was initiated to deliver Ponseti treatment for CTEV, while addressing standard of care and resource allocation. The aim of this study was to assess feasibility and outcomes of the corrective phase of Ponseti service delivery using this model.

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Prior to the availability of vaccines, mortality for hip fracture patients with concomitant COVID-19 infection was three times higher than pre-pandemic rates. The primary aim of this study was to determine the 30-day mortality rate of hip fracture patients in the post-vaccine era.

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Ganz’s studies made it possible to address joint deformities on both the femoral and acetabular side brought about by Perthes’ disease. Femoral head reduction osteotomy (FHRO) was developed to improve joint congruency, along with periacetabular osteotomy (PAO), which may enhance coverage and containment. The purpose of this study is to show the clinical and morphological outcomes of the technique and the use of an implemented planning approach.

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To assess the cost-effectiveness of a two-layer compression bandage versus a standard wool and crepe bandage following total knee arthroplasty, using patient-level data from the Knee Replacement Bandage Study (KReBS).

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The number of females within the speciality of trauma and orthopaedics (T&O) is increasing. The aim of this study was to identify: 1) current attitudes and behaviours of UK female T&O surgeons towards pregnancy; 2) any barriers faced towards pregnancy with a career in T&O surgery; and 3) areas for improvement.

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To examine whether natural language processing (NLP) using a clinically based large language model (LLM) could be used to predict patient selection for total hip or total knee arthroplasty (THA/TKA) from routinely available free-text radiology reports.

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Deprivation underpins many societal and health inequalities. COVID-19 has exacerbated these disparities, with access to planned care falling greatest in the most deprived areas of the UK during 2020. This study aimed to identify the impact of deprivation on patients on growing waiting lists for planned care.

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Global literature suggests that female surgical trainees have lower rates of independent operating (operative autonomy) than their male counterparts. The objective of this study was to identify any association between gender and lead/independent operating in speciality orthopaedic trainees within the UK national training programme.

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To identify the responsiveness, minimal clinically important difference (MCID), minimal clinical important change (MIC), and patient-acceptable symptom state (PASS) thresholds in the 36-item Short Form Health Survey questionnaire (SF-36) (v2) for each of the eight dimensions and the total score following total knee arthroplasty (TKA).

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To compare the cost-utility of removable brace compared with cast in the management of adult patients with ankle fracture.

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Thresholds of acceptable early migration of the components in total knee arthroplasty (TKA) have traditionally ignored the effects of patient and implant factors that may influence migration. The aim of this study was to determine which of these factors are associated with overall longitudinal migration of well-fixed tibial components following TKA.

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The cemented Oxford unicompartmental knee arthroplasty (OUKA) features two variants: single and twin peg OUKA. The purpose of this study was to assess the stability of both variants in a worst-case scenario of bone defects and suboptimal cementation.

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Navigation devices are designed to improve a surgeon’s accuracy in positioning the acetabular and femoral components in total hip arthroplasty (THA). The purpose of this study was to both evaluate the accuracy of an optical computer-assisted surgery (CAS) navigation system and determine whether preoperative spinopelvic mobility (categorized as hypermobile, normal, or stiff) increased the risk of acetabular component placement error.

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The aim of this study was to assess medium-term improvements following total hip arthroplasty (THA), and to evaluate what effect different preoperative Oxford Hip Score (OHS) thresholds for treatment may have on patients’ access to THA and outcomes.

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An objective technological solution for tracking adherence to at-home shoulder physiotherapy is important for improving patient engagement and rehabilitation outcomes, but remains a significant challenge. The aim of this research was to evaluate performance of machine-learning (ML) methodologies for detecting and classifying inertial data collected during in-clinic and at-home shoulder physiotherapy exercise.

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Studies on long-term patient-reported outcomes after open surgery for triangular fibrocartilage complex (TFCC) are scarce. Surgeons and patients would benefit from self-reported outcome data on pain, function, complications, and satisfaction after this surgery to enhance shared decision-making. The aim of this study is to determine the long-term outcome of adults who had open surgery for the TFCC.

Aims

In total knee arthroplasty (TKA), blood loss continues internally after surgery is complete. Typically, the total loss over 48 postoperative hours can be around 1,300 ml, with most occurring within the first 24 hours. We hypothesize that the full potential of tranexamic acid (TXA) to decrease TKA blood loss has not yet been harnessed because it is rarely used beyond the intraoperative period, and is usually withheld from ‘high-risk’ patients with a history of thromboembolic, cardiovascular, or cerebrovascular disease, a patient group who would benefit greatly from a reduced blood loss.

Little guidance exists in the current literature regarding which patient recorded outcome measures (PROMs) are most clinically appropriate following anterior cruciate ligament reconstruction (ACL) surgery, and what results surgeons should expect or accept. Many PROMs have been validated, but their “ideal” results have not been published, limiting a surgeon's ability to compare their patients’ outcomes with those of their colleagues. We undertook a systematic review of PROMs for ACL to look at common usage and outcomes. After appropriate paper selection, we then undertook a pragmatic meta-analysis (i.e., including all papers that fulfilled the selection criteria, regardless of CONSORT status) and calculated weighted mean outcome scores and standard deviations for the most commonly used PROMs. A comprehensive literature search of all English articles of PubMed and other sources including search terms (‘Patient related outcome measure’ or ‘PROM’) AND ‘anterior cruciate ligament’ (limited to abstract/title) yielded 722 articles. Title review narrowed this to 268, and abstracts review to 151, of which 88 were included in our meta-analysis. Weighted mean and standard deviations were calculated for IKDC, KOOS, Lysholm, Teneger and “VAS Pain” PROMs as the most commonly reported. We identified significant, novel findings relating to selected PROMs and (i) demographics including age, gender and body mass index, (ii) surgical factors including bundle count, strand count, and graft type, and (iii) post operative complications. We clarified the most commonly used PROMs for ACL, and their weighted means and standard deviations. This will allow surgeons to compare results with colleagues, ensuring they meet international levels of quality in PROMs. We have also updated which patient and operative factors have an impact on PROMs scoring to allow for population variance

Patients may be able to return to higher level activities following hip arthroplasty with modern techniques and prostheses, but the Oxford hip score, the standard PROM used by the NJS exhibits severe skew and kurtosis. The commonest score is 48/48. Most patients score above 40 preventing any discrimination between approaches or prostheses. We therefore sought both subjective and objective metrics which were relevant and valid without skew or high kurtosis in postoperative patients. The Metabolic Equivalent of Task (MET) reports energy usage in kcal/min burnt across a range of activities, condensed into a score of 0–25. A MET over 8 is considered ‘conditioning exercise’ tethered to life expectancy. A 2 point difference in average MET is considered a clinically relevant difference. Walking speed is a simple valid metric tethered to life expectancy, with a 0.1m/sec difference in walking speed equates to a clinically important difference. Oxford Hip Score (OHS), and the MET were prospectively recorded in 221 primary hip arthroplasty procedures pre-operatively and at 1-year using a web based application. Pre and postoperative Gait analysis was undertaken on a subgroup of 34 patients, in comparison with age and sex matched controls. Post-operatively, the OHS demonstrated significant skewed distributions with ceiling effects of 41% scoring 48/48. The MET was normally distributed around a mean of 10.3, with a standard deviation of 3.8 and no ceiling effect. Walking speed was normally distributed around a mean of 1.8m/sec, with a standard deviation was 0.15 m/sec. The MET is a simple patient reported score, which is normally distributed in patients following hip arthroplasty, around a mean of 10.3 with a standard deviation of 3.8. This valid activity metric correlates well with fast walking speed. This is also normally distributed with a standard deviation of over 0.1m/sec confirming low kurtosis. These simple measures have face validity: undertaking less active pastimes and being unable to keep up with other walkers are obviously inadvisable. The normal kurtosis of these metrics suggest that they may able to detect clinically relevant differences in outcome which are undetectable with commonly used PROMs. For surgeons developing less invasive approaches or using novel stems, these measures may detect clinically important improvements undetectable by the Oxford Hip Score

Utility score is a preference-based measure of general health state – where 0 is equal to death, and 1 is equal to perfect health. To understand a patient's smallest perceptible change in utility score, the minimal clinically important difference (MCID) can be calculated. However, there are multiple methods to calculate MCID with no consensus about which method is most appropriate. The aim of this study is to calculate MCID values for the Veterans-RAND 12 (VR12) utility score using varying methods. Our hypothesis is that different methods will yield different MCID values. A tertiary institutional registry (SMART) was used as the study cohort. Patients who underwent unilateral TKA for osteoarthritis from January 2012 to January 2020 were included. Utility score was calculated from VR12 responses using the standardised Brazier's method. Distribution and anchor methods were used for the MCID calculation. For distribution methods, 0.5 standard deviations of the baseline and change scores were used. For anchor methods, the physical and emotional anchor questions in the VR12 survey were used to benchmark utility score outcomes. Anchor methods included mean difference in change score, mean difference in 12 month score, and receiver operating characteristics (ROC) analysis with the Youden index. Complete case analysis of 1735 out of 1809 eligible patients was performed. Significant variation in the MCID estimates for VR12 utility score were reported dependent on the calculation method used. The MCID estimate from 0.5 standard deviations of the change score was 0.083. The MCID estimate from the ROC analysis method using physical or emotional anchor question improvement was 0.115 (CI95 0.08-0.14; AUC 0.656). Different MCID calculation methods yielded different MCID values. Our results suggest that MCID is not an umbrella concept but rather many distinct concepts. A general consensus is required to standardise how MCID is defined, calculated, and applied in clinical practice

Successful estimation of postoperative PROMs prior to a joint replacement surgery is important in deciding the best treatment option for a patient. However, estimation of the outcome is associated with substantial noise around individual prediction. Here, we test whether a classifier neural network can be used to simultaneously estimate postoperative PROMs and uncertainty better than current methods. We perform Oxford hip score (OHS) estimation using data collected by the NJR from 249,634 hip replacement surgeries performed from 2009 to 2018. The root mean square error (RMSE) of the various methods are compared to the standard deviation of outcome change distribution to measure the proportion of the total outcome variability that the model can capture. The area under the curve (AUC) for the probability of the change score being above a certain threshold was also plotted. The proposed classifier NN had a better or equivalent RMSE than all other currently used models. The standard deviation for the change score for the entire population was 9.93, which can be interpreted as the RMSE that would be achieved for a model that gives the same estimation for all patients regardless of the covariates. However, most of the variation in the postoperative OHS/OKS change score is not captured by the models, confirming the importance of accurate uncertainty estimation. The threshold AUC shows similar results for all methods close to a change score of 20 but demonstrates better accuracy of the classifier neural network close to 0 change and greater than 30 change, showing that the full probability distribution performed by the classifier neural network resulted in a significant improvement in estimating the upper and lower quantiles of the change score probability distribution. Consequently, probabilistic estimation as performed by the classifier NN is the most adequate approach to this problem, since the final score has an important component of uncertainty. This study shows the importance of uncertainty estimation to accompany postoperative PROMs prediction and presents a clinically-meaningful method for personalised outcome that includes such uncertainty estimation

Bone age is a radiographical assessment used in pediatric medicine due to its relative objectivity in determining biological maturity compared to chronological age and size.1 Currently, Greulich and Pyle (GP) is one of the most common methods used to determine bone age from hand radiographs.2–4 In recent years, new methods were developed to increase the efficiency in bone age analysis like the shorthand bone age (SBA) and the automated artificial intelligence algorithms. The purpose of this study is to evaluate the accuracy and reliability of these two methods and examine if the reduction in analysis time compromises their accuracy. Two hundred thirteen males and 213 females were selected. Each participant had their bone age determined by two separate raters using the GP (M1) and SBA methods (M2). Three weeks later, the two raters repeated the analysis of the radiographs. The raters timed themselves using an online stopwatch while analyzing the radiograph on a computer screen. De-identified radiographs were securely uploaded to an automated algorithm developed by a group of radiologists in Toronto. The gold standard was determined to be the radiology report attached to each radiograph, written by experienced radiologists using GP (M1). For intra-rater variability, intraclass correlation analysis between trial 1 (T1) and trial 2 (T2) for each rater and method was performed. For inter-rater variability, intraclass correlation was performed between rater 1 (R1) and rater 2 (R2) for each method and trial. Intraclass correlation between each method and the gold standard fell within the 0.8–0.9 range, highlighting significant agreement. Most of the comparisons showed a statistically significant difference between the two new methods and the gold standard; however it may not be clinically significant as it ranges between 0.25–0.5 years. A bone age is considered clinically abnormal if it falls outside 2 standard deviations of the chronological age; standard deviations are calculated and provided in GP atlas.6–8 For a 10-year old female, 2 standard deviations constitute 21.6 months which far outweighs the difference reported here between SBA, automated algorithm and the gold standard. The median time for completion using the GP method was 21.83 seconds for rater 1 and 9.30 seconds for rater 2. In comparison, SBA required a median time of 7 seconds for rater 1 and 5 seconds for rater 2. The automated method had no time restraint as bone age was determined immediately upon radiograph upload. The correlation between the two trials in each method and rater (i.e. R1M1T1 vs R1M1T2) was excellent (κ= 0.9–1) confirming the reliability of the two new methods. Similarly, the correlation between the two raters in each method and trial (i.e. R1M1T1 vs R2M1T1) fell within the 0.9–1 range. This indicates a limited variability between raters who may use these two methods. The shorthand bone age method and an artificial intelligence automated algorithm produced values that are in agreement with the gold standard Greulich and Pyle, while reducing analysis time and maintaining a high inter-rater and intra-rater reliability

The functional pelvic tilt when standing and sitting forward of 7402 cases on the OPS, Optimized Ortho, Australia Data Base were reviewed. All patients had undergone lateral radiographs when standing simulating extension of the hip, and sitting forward when the hip is near full flexion. Pelvic tilt was measured as the angle of the Anterior Pelvic Plane to the vertical Sagittal Plane, rotation anteriorly being given a positive value. Pelvises that had rotated more than 13 degrees anteriorly (+ve) when sitting forward or posteriorly (-ve) when standing were considered to place the hip at increased risk of dislocation or edge loading when flexed or extending respectively. This degree of rotation has the effect of changing the acetabular version by approximately10. 0. Most safe zones that have been described have given a range of anteversion of 20. 0. as safe. A change of 10. 0. would potentially place the acetabular orientation outside this range. Further, clinical studies have supported this concept. All lateral radiographs were reviewed to confirm that 281 had undergone instrumented spinal fusion at some level between T12 and S1. There was a large variability in the number and the levels arthrodesed. The range of pelvic mobility in the non-arthrodesed group in extension was −37. 0. to 31. 0. (mean −0.9. 0. , Standard deviation 7.49) and in flexed position was −70. 0. to 49. 0. (mean −1.9. 0. , Standard deviation 14.01). For the group with any fusion the range of pelvic tilt in extension was −31. 0. to 22. 0. (mean −4. 0. , Standard deviation 8.21) and flexed −32. 0. to 46. 0. (mean 4.4. 0. , Standard deviation 13.79). Of the 7121 cases without instrumented fusion, 15.5% were considered to be at risk when in flexion and 6.1% when extended. The risk for those with any fusion was approximately doubled in both flexion and extension. Further, those with extensive arthrodesis from T12 to S1 had a range of pelvic tilts similar to the non-fused group, although they had a significantly higher percentage of cases in the ‘at risk’ zones. The proportion of the cases in the ‘at risk’ zones decreased progressively as the arthrodesed levels moved from L5/S1 to the upper lumbar spine, and with decreasing number of levels fused. Conclusion. Spinal fusion is not just one group as there are many combinations of different levels fused. Patients with instrumented spinal fusions do have a proportionately high risk of failure of their THR than the majority of cases with no instrumentation, though the risk varies significantly with the number of levels and actual levels arthrodesed. Further approximately 21% of cases with no spinal fusion have functional pelvic movements that would potentially place them ‘at risk’ of edge loading or dislocation. For any figures or tables, please contact authors directly

Aims. Radiological residual acetabular dysplasia (RAD) has been reported in up to 30% of children who had successful brace treatment of infant developmental dysplasia of the hip (DDH). Predicting those who will resolve and those who may need corrective surgery is important to optimize follow-up protocols. In this study we have aimed to identify the prevalence and predictors of RAD at two years and five years post-bracing. Methods. This was a single-centre, prospective longitudinal cohort study of infants with DDH managed using a published, standardized Pavlik harness protocol between January 2012 and December 2016. RAD was measured at two years’ mean follow-up using acetabular index-lateral edge (AI-L) and acetabular index-sourcil (AI-S), and at five years using AI-L, AI-S, centre-edge angle (CEA), and acetabular depth ratio (ADR). Each hip was classified based on published normative values for normal, borderline (1 to 2 standard deviations (SDs)), or dysplastic (> 2 SDs) based on sex, age, and laterality. Results. Of 202 infants who completed the protocol, 181 (90%) had two and five years’ follow-up radiographs. At two years, in 304 initially pathological hips, the prevalence of RAD (dysplastic) was 10% and RAD (borderline) was 30%. At five years, RAD (dysplastic) decreased to 1% to 3% and RAD (borderline) decreased to < 1% to 2%. On logistic regression, no variables were predictive of RAD at two years. Only AI-L at two years was predictive of RAD at five years (p < 0.001). If both hips were normal at two years’ follow-up (n = 96), all remained normal at five years. In those with bilateral borderline hips at two years (n = 21), only two were borderline at five years, none were dysplastic. In those with either borderline-dysplastic or bilateral dysplasia at two years (n = 26), three (12%) were dysplastic at five years. Conclusion. The majority of patients with RAD at two years post-brace treatment, spontaneously resolved by five years. Therefore, children with normal radiographs at two years post-brace treatment can be discharged. Targeted follow-up for those with abnormal AI-L at two years will identify the few who may benefit from surgical correction at five years’ follow-up. Cite this article: Bone Joint J 2024;106-B(7):744–750

INTRODUCTION. Determining proper joint tension in reverse total shoulder arthroplasty (rTSA) can be a challenging task for shoulder surgeons. Often, this is a subjective metric learned by feel during fellowship training with no real quantitative measures of what proper tension encompasses. Tension too high can potentially lead to scapular stress fractures and limitation of range of motion (ROM), whereas tension too low may lead to instability. New technologies that detect joint load intraoperatively create the opportunity to observe rTSA joint reaction forces in a clinical setting for the first time. The purpose of this study was to observe the differences in rTSA loads in cases that utilized two different humeral liner sizes. METHODS. Ten different surgeons performed a total of 37 rTSA cases with the same implant system. During the procedure, each surgeon reconstructed the rTSA implants to his or her own preferred tension. A wireless load sensing humeral liner trial (VERASENSE for Equinoxe, OrthoSensor, Dania Beach, FL) was used in lieu of a traditional plastic humeral liner trial to provide real-time load data to the operating surgeon during the procedure. Two humeral liner trial sizes were offered in 38mm and 42mm curvatures and were selected each case based on surgeon preference. To ensure consistent measurements between surgeons, a standardized ROM assessment consisting of four dynamic maneuvers (maximum internal to external rotation at 0°, 45°, and 90° of abduction, and a maximum flexion/extension maneuver) and three static maneuvers (arm overhead, across the body, and behind the back) was completed in each case. Deidentified load data in lbf was collected and sorted based on which size liner was selected. Differences in means for minimum and maximum load values for the four dynamic maneuvers and differences in means for the three static maneuvers were calculated using 2-tailed unpaired t-tests. RESULTS. No significant differences were observed for the flexion/extension maneuver between the 38mm and 42mm liner sizes, but a significant difference was observed for every internal/external rotation assessment at 0°, 45°, and 90° of abduction. No significant differences were observed for the across the body and overhead maneuvers, but a significant difference was observed for the behind the back maneuver (p = 0.015). Standard deviations were pronounced across all maneuvers. CONCLUSION. This study observed significant differences in intraoperative load values in rTSA when comparing different humeral liner sizes. Limitations of this study include the small sample sizes and large standard deviations observed, as well as comparing across multiple patients and multiple surgeons. Area for future work includes comparing load values with postoperative functional results and complication risks for short, midterm, and long-term outcomes in efforts to find the optimal load range for a given patient

Functional outcomes are commonly reported in studies of musculoskeletal oncology patients undergoing limb salvage surgery; however, interpretation requires knowledge of the smallest amount of improvement that is important to patients – the minimally important difference (MID). We established the MIDs for the Musculoskeletal Tumor Society Rating Scale (MSTS) and Toronto Extremity Salvage Score (TESS) in patients with bone tumors undergoing lower limb salvage surgery. This study was a secondary analysis of the recently completed PARITY (Prophylactic Antibiotic Regimens in Tumor Surgery) study. This data was used to calculate: (1) the anchor-based MIDs using an overall function scale and a receiver operating curve analysis, and (2) the distribution-based MIDs based on one-half of the standard deviation of the change scores from baseline to 12-month follow-up, for both the MSTS and TESS. There were 591 patients available for analysis. The Pearson correlation coefficients for the association between changes in MSTS and TESS scores and changes in the external anchor scores were 0.71 and 0.57, indicating “high” and “moderate” correlation. Anchor-based MIDs were 12 points and 11 points for the MSTS and TESS, respectively. Distribution-based calculations yielded MIDs of 16-17 points for the MSTS and 14 points for the TESS. The current study proposes MID scores for both the MSTS and TESS outcome measures based on 591 patients with bone tumors undergoing lower extremity endoprosthetic reconstruction. These thresholds will optimize interpretation of the magnitude of treatment effects, which will enable shared decision-making with patients in trading off desirable and undesirable outcomes of alternative management strategies. We recommend anchor-based MIDs as they are grounded in changes in functional status that are meaningful to patients

Successful estimation of postoperative PROMs prior to a joint replacement surgery is important in deciding the best treatment option for a patient. However, estimation of the outcome is associated with substantial noise around individual prediction. Here, we test whether a classifier neural network can be used to simultaneously estimate postoperative PROMs and uncertainty better than current methods. We perform Oxford hip score (OHS) estimation using data collected by the NJR from 249,634 hip replacement surgeries performed from 2009 to 2018. The root mean square error (RMSE) of the various methods are compared to the standard deviation of outcome change distribution to measure the proportion of the total outcome variability that the model can capture. The area under the curve (AUC) for the probability of the change score being above a certain threshold was also plotted. The proposed classifier NN had a better or equivalent RMSE than all other currently used models. The threshold AUC shows similar results for all methods close to a change score of 20 but demonstrates better accuracy of the classifier neural network close to 0 change and greater than 30 change, showing that the full probability distribution performed by the classifier neural network resulted in a significant improvement in estimating the upper and lower quantiles of the change score probability distribution. Consequently, probabilistic estimation as performed by the classifier NN is the most adequate approach to this problem, since the final score has an important component of uncertainty. This study shows the importance of uncertainty estimation to accompany postoperative PROMs prediction and presents a clinically-meaningful method for personalised outcome that includes such uncertainty estimation

Cam-type femoroacetabular impingement is caused by bone excess on the femoral neck abutting the acetabular rim. This can cause cartilage and labral damage due to increased contact pressure as the cam moves into the acetabulum. However, the damage mechanism and the influence of individual mechanical factors (such as sliding distance) are poorly understood. The aim of this study was to identify the cam sliding distance during impingement for different activities in the hip joint. Motion data for 12 different motion activities from 18 subjects, were applied to a hip shape model (selected as most likely to cause damage, anteriorly positioned with a maximum alpha angle of 80°). The model comprised of a pointwise representation of the acetabular rim and points on the femoral head and neck where the shape deviated from a sphere (software:Matlab). The movement of each femoral point was tracked in 3D while an activity motion was applied, and impingement recorded when overlap between a cam point and the acetabular rim occurred. Sliding distance was recorded during impingement for each relevant femoral point. Angular sliding distances varied for different activities. The highest mean (±SD) sliding distance was for leg-crossing (42.62±17.96mm) and lowest the trailing hip in golf swing (2.17±1.11mm). The high standard deviation in the leg crossing sliding distances, indicates subjects may perform this activity in a different manner. This study quantified sliding distance during cam impingement for different activities. This is an important parameter for determining how much the hip moves during activities that may cause damage and will provide information for future experimental studies

Background. The use of a knotless TightRope for the stabilisation of a syndesmotic injury is a well-recognised mode of fixation. It has been described that the device can be inserted using a “closed” technique. This presents a risk of saphenous nerve entrapment and post-operative pain. Aim. We aimed to establish the actual risk of injury to the Saphenous Nerve using a “closed” technique for the insertion of a TightRope. Method. 20 TightRopes were inserted into Fresh Frozen Cadavers. This was done using the senior authors preferred technique of divergent tightropes with the distal implant directed slightly anterior to the fibula-tibia axis and the proximal implant slightly posterior in order to simulate the greatest risk to the nerve. This was done under image Intensifier guidance to simulate an intraoperative environment. The medial side of the distal tibia was then dissected to directly record and measure the relationship of the TightRope to the Saphenous Nerve. Measurements were taken using digital calipers from the centre of the button on the medial side of the TightRope to the centre of the nerve at the point of closest proximity. Results. 12 TightRopes were found to exit posterior to the nerve, 7 anterior and 1 penetrated through the centre of the nerve. The mean distance from the centre of the button to the nerve was 6.99mm (range 0.72–14.52mm, standard deviation 4.33mm). In 9 of the 20 TightRopes, the nerve was found to be less than 5mm away. Conclusion. Our findings demonstrated that the risks of damaging or indeed entrapping the Saphenous nerve were high, and therefore we would advocate an open incision on the medial side with judicious exploration to ensure there is no damage to the medial neurological structures

Abstract. Background. Aim of this study is to determine the difference between re-operation rates after conventional Methods of fixation of patella fractures using Metallic implants and novel technique of all suture fixation using Ethibond or fiber tape. Methods. This is a retrospective comparative analysis involving 62 patients who had a transverse patellar fracture and underwent surgery between January 2013 to December 2021. Selected patients were divided, based on different fixation methods used, into four groups - TBW group, CC screw group, Encirclage group and Suture Fixation Group. Patients were followed till bone union was evident on radiographs. Number of patients in Metallic implant group undergoing repeat operation were compared with the patients who underwent patella fracture fixation using all suture technique. Mean and standard deviation (SD) were calculated for all continuous variables. Mean of the two groups was compared using unpaired t-test. Results. TBW was the most common method of fixation used in 41(66.1%) patients. 7 patients each underwent surgery using CC screw, Encirclage +/− TBW, and suture fixation respectively. Bone union was seen in about 85% of patients in all the groups suggesting all treatment modalities lead to good fracture healing. 15 patients(36.6%) of patients in TBW group and 3 patients(42.9%) in encirclage group had implant removal because of hardware-related complications (p<0.001). None of the patient who underwent All suture Fixation underwent re-operation. Conclusion. The results suggest that Suture fixation of patellar fractures is a valid treatment modality giving excellent results with similar bone union rates without any complications

In this RCT the primary aim was to assess whether a short (125mm) Exeter V40 stem offered an equivalent hip specific function compared to the standard (150mm) stem when used for cemented total hip arthroplasty (THA). Secondary aims were to evaluate health-related quality of life (HRQoL), patient satisfaction, stem height and alignment, radiographic loosening, and complications between the two stems. A prospective multicentre double-blind randomised control trial was conducted. During a 15-month period, 220 patients undergoing THA were randomised to either a standard (n=110) or short (n=110) stem Exeter. There were no significant (p≥0.065) differences in preoperative variables between the groups. Functional outcomes and radiographic assessment were undertaken at 1- and 2-years. There were no differences (p=0.428) in hip specific function according to the Oxford hip score at 1-year (primary endpoint) or at 2-years (p=0.767) between the groups. The short stem group had greater varus angulation (0.9 degrees, p=0.003) when compared to the standard group and were more likely (odds ratio 2.42, p=0.002) to have varus stem alignment beyond one standard deviation from the mean. There were no significant (p≥0.083) differences in the Forgotten joint scores, EuroQol-5-Dimension, EuroQol-VAS, Short form 12, patient satisfaction, complications, stem height or radiolucent zones at 1 or 2-years between the groups. The Exeter short stem offers equivalent hip specific function, HRQoL, patient satisfaction, and limb length when compared to the standard stem at 2-years post-operation. However, the short stem was associated with a greater rate of varus malalignment which may influence future implant survival

Introduction. Recent technological advancements have led to the introduction of robotic-assisted total knee arthroplasty to improve the accuracy and precision of bony resections and implant position. However, the in vivo accuracy is not widely reported. The primary objective of this study is to determine the accuracy and precision of a cut block positioning robotic arm. Method. Seventy-seven patients underwent total knee arthroplasty with various workflows and alignment targets by three arthroplasty-trained surgeons with previous experience using the ROSA® Knee System. Accuracy and precision were determined by measuring the difference between various workflow time points, including the final pre-operative plan, validated resection angle, and post-operative radiographs. The mean difference between the measurements determined accuracy, and the standard deviation represented precision. Results. The accuracy and precision for all angles comparing the final planned resection and validated resection angles was 0.90° ± 0.76°. The proportion within 3° ranged from 97.9% to 100%. The accuracy and precision for all angles comparing the final intra- operative plan and post-operative radiographs was 1.95 ± 1.48°. The proportion of patients within 3° was 93.2%, 95.3%, 96.6%, and 71.4% for the distal femur, proximal tibia, femoral flexion, and tibial slope angles when the final intra-operative plan was compared to post-operative radiographs. No patients had a postoperative complication requiring revision at the final follow-up. Conclusions. This study demonstrates that the ROSA Knee System has accurate and precise coronal plane resections with few outliers. However, the tibial slope demonstrated decreased accuracy and precision were measured on post-operative short-leg lateral radiographs with this platform

Femoroacetabular Impingement (FAI) syndrome, characterised by abnormal hip contact causing symptoms and osteoarthritis, is measured using the International Hip Outcome Tool (iHOT). This study uses machine learning to predict patient outcomes post-treatment for FAI, focusing on achieving a minimally clinically important difference (MCID) at 52 weeks. A retrospective analysis of 6133 patients from the NAHR who underwent hip arthroscopic treatment for FAI between November 2013 and March 2022 was conducted. MCID was defined as half a standard deviation (13.61) from the mean change in iHOT score at 12 months. SKLearn Maximum Absolute Scaler and Logistic Regression were applied to predict achieving MCID, using baseline and 6-month follow-up data. The model's performance was evaluated by accuracy, area under the curve, and recall, using pre-operative and up to 6-month postoperative variables. A total of 23.1% (1422) of patients completed both baseline and 1-year follow-up iHOT surveys. The best results were obtained using both pre and postoperative variables. The machine learning model achieved 88.1% balanced accuracy, 89.6% recall, and 92.3% AUC. Sensitivity was 83.7% and specificity 93.5%. Key variables determining outcomes included MCID achievement at 6 months, baseline iHOT score, 6-month iHOT scores for pain, and difficulty in walking or using stairs. The study confirmed the utility of machine learning in predicting long-term outcomes following arthroscopic treatment for FAI. MCID, based on the iHOT 12 tools, indicates meaningful clinical changes. Machine learning demonstrated high accuracy and recall in distinguishing between patients achieving MCID and those who did not. This approach could help early identification of patients at risk of not meeting the MCID threshold one year after treatment

Current treatment options for displaced acetabular fractures in elderly patients include non-surgical management, surgical fixation and surgical fixation with simultaneous hip replacement, the so-called “fix-and-replace”™. There remains a paucity of evidence to guide surgeons in decision making for these difficult injuries. The aim of this study was to assess the feasibility of performing an appropriately powered RCT between treatment options for acetabular fractures in older patients. This was an NIHR funded feasibility triple-arm RCT with participation from 7 NHS MTCs. Patients older than 60 were recruited if they had an acetabular fracture deemed sufficiently displaced for the treating surgeon to consider surgical fixation. Randomisation was performed on a 1:1:1 basis. The three treatment arms were non-surgical management, surgical fixation and fix-and-replace. Feasibility was assessed by willingness of patients to participate and clinicians to recruit, drop out rate, estimates of standard deviation to inform the sample size calculation for the full trial and completion rates to inform design of a future definitive trial. EQ-5D was the primary outcome measure at 6 months, OHS and Disability Rating Index were secondary outcome measures. Of 117 eligible patients, 60 were randomised whilst 50 declined study participation. Nine patients did not receive their allocated intervention. Analysis was performed on an intention to treat basis. During the study period 4 patients withdrew before final review, 4 patients died and 1 was lost to follow-up. The estimated sample size for a full scale study was calculated to be 1474 participants for an EQ-5D MCID of 0.06 with a power of 0.8. This feasibility study suggests a full scale trial would require international collaboration. This study also has provided observed safety data regarding mortality and morbidity for the fix-and-replace procedure to aid surgeons in the decision-making process when considering treatment options

Background. There are many different procedures described for the correction of hallux valgus deformity. Minimally invasive surgery has become increasingly popular, with clinical and radiological outcomes comparable to traditional open osteotomy approaches. There is increasing interest in hallux valgus deformity correction using third-generation minimally invasive chevron akin osteotomy (MICA) technique. Objective. To assess the radiographic correction and 2 year clinical outcomes of third-generation MICA using validated outcome measures. Methods. This is a prospective single-surgeon case series of 420 consecutive feet undergoing MICA surgery between July 2014 and November 2018. Primary clinical outcome measures included the Manchester-Oxford Foot Questionnaire (MOXFQ), EQ-5D, and the Visual Analogue Pain Scale. Secondary outcome measures included radiographic parameters, and complication rates. Results. Pre-operative and 2 year post-operative patient reported outcomes were collected for 334 feet (79.5%). At minimum 2 year follow-up, the MOXFQ scores (mean ± standard deviation (SD)) had improved for each domain: pain; pre-operative 43.9±21.0 reduced to 9.1±15.6 post-operatively (p<0.001), walking and standing; pre-operative 38.2±23.6 reduced to 6.5±14.5 post-operatively (p<0.001) and social interaction; pre-operative 47.6±22.1, reduced to 6.5±13.5 post-operatively (p<0.001). At 2 year follow-up, the VAS Pain score (mean ± SD) improved from a pre-operative of 31.3±22.4 to 8.3±16.2 post-operatively (p<0.001). 1–2 intermetatarsal angle (mean ± SD) reduced from 15.4°±3.5° to 5.8°±3.1° (p<0.001) and hallux valgus angle reduced from 33.1°±10.2° to 9.0°±5.0° post-operatively (p<0.001). Conclusion. Third-generation MICA showed significant improvement in clinical outcomes at 2 year follow-up and can be successfully used for correction of a wide range of hallux valgus deformities

The angle of acetabular inclination is an important measurement in total hip replacement (THR) procedures. Determining the acetabular component orientation intra-operatively remains a challenge. An increasing number of innovators have described techniques and devices to achieve it. This paper describes a mechanical inclinometer design to measure intra-operative acetabular cup inclination. Then, the mechanical device is tested to determine its accuracy. The aim was to design an inclinometer to measure inclination without existing instrumentation modification. The device was designed to meet the following criteria: 1. measure inclination with acceptable accuracy (+/− 5o); 2. easy to use intra-operatively (handling & visualization); 3. adaptable and useable with majority of instrumentation kits without modification; 4. sterilizable by all methods; 5. robust/reusable. The prototype device was drafted by computer aided design (CAD) software. Then a prototype was constructed using a 3D printer to establish the final format. The final device was CNC machined from SAE 304 stainless steel. The design uses an eccentrically weighted flywheel mounted on two W16002-2RS ball bearings pressed into symmetrical housing components. The weighted wheel is engraved with calibrated markings relative to its mass centre. Device functioning is dependent on gravity maintaining the weighted wheel in a fixed orientation while the housing can adapt to the calibration allowing for determining the corresponding measurement. The prototype device accuracy was compared to a digital device. A digital protractor was used to create an angle. The mechanical inclinometer (user blinded to digital reading) was used to determine the angle and compared to the digital reading. The accuracy of the device compared to the standard freehand technique was assessed using a saw bone pelvis fixed in a lateral decubitus position. 18 surgeons (6 expert, 6 intermediate, 6 novice) were asked to place an uncemented acetabular cup in a saw bone pelvis to a target of 40 degrees. First freehand then using the inclinometer. The inclination was determined using a custom-built inertial measurement unit with the user blinded to the result. Comparison between the mechanical and digital devices showed that the mechanical device had an average error of −0.2, a standard deviation of 1.5, and range −3.3 to 2.6. The average root mean square error was 1.1 with a standard deviation of 0.9. Comparison of the inclinometer to the freehand technique showed that with the freehand component placement 50% of the surgeons were outside the acceptable range of 35–45 degrees. The use of the inclinometer resulted all participants to achieve placement within the acceptable range. It was noted that expert surgeons were more accurate at achieving the target inclination when compared to less experienced surgeons. This work demonstrates that the design and initial testing of a mechanical inclinometer is suitable for use in determining the acetabular cup inclination in THR. Experimental testing showed that the device is accurate to within acceptable limits and reliably improved the accuracy of uncemented cup implantation in all surgeons

Critical-sized bone defects can result from trauma, inflammation, and tumor resection. Such bone defects, often have irregular shapes, resulting in the need for new technologies to produce suitable implants. Bioprinting is an additive manufacturing method to create complex and individualised bone constructs, which can already include vital cells. In this study, we established an extrusion-based printing technology to produce osteoinductive scaffolds based on polycaprolactone (PCL) combined with calcium phosphate, which is known to induce osteogenic differentiation of stem cells. The model was created in python based on the signed distance functions. The shape of the 3D model is a ring with a diameter of 20 mm and a height of 10 mm with a spongiosa-like structure. The interconnected irregular pores have a diameter of 2 mm +/− 0.2 mm standard deviation. Extrusion-based printing was performed using the BIO X6. To produce the bioink, PCL (80 kDa) was combined with calcium phosphate nanopowder (> 150 nm particle size) under heating. After printing, 5 × 10. 6. hMSC were seeded on the construct using a rotating incubator. We were able to print a highly accurate ring construct with an interconnected pore structure. The PCL combined with calcium phosphate particles resulted in a precise printed construct, which corresponded to the 3D model. The bioink containing calcium phosphate nanoparticles had a higher printing accuracy compared to PCL alone. We found that hMSC cultured on the construct settled in close proximity to the calcium phosphate particles. The hMSC were vital for 22 days on the construct as demonstrated by life/dead staining. The extrusion printing technology enables to print a mechanically stable construct with a spongiosa-like structure. The porous PCL ring could serve as an outer matrix for implants, providing the construct the stability of natural bone. To extend this technology and to improve the implant properties, a biologised inner structure will be integrated into the scaffold in the future

Background. Lateral lumbar spine statistical shape models (SSM) have been used previously to describe associations with osteoarthritis and back pain. However, associations with factors such as osteoporosis, menopause and parity have not been explored. Methods and Results. A 143-point SSM, describing L1 to the top of L5, was applied to lateral spine iDXA scans from UK Biobank. Associations with self-reported osteoporosis, menopause, parity and back pain and the first 10 modes of variation were examined using adjusted binary logistic regression or linear regression (adjusted for age, height, weight and total spine BMD). We report odds ratios with 95% confidence intervals for each standard deviation change in mode. Complete data were available for 2494 women. Mean age was 61.5 (± 7.4) years. 1369 women reported going through menopause, 96 women self-reported osteoporosis and 339 women reported chronic back pain. 80% of women reported at least 1 live birth. Lumbar spine shape was not associated with back pain in this cohort. Two modes were associated with menopause (modes 1 & 2), 1 mode with parity (mode 1) and 2 modes with osteoporosis (modes 3 & 5). Mode 1 (43.6% total variation), describing lumbar curvature was positively associated with both menopause [OR 1.15 95% CI 1.00–1.33, p=0.05] and parity [OR 1.058 95% CI 1.03–1.0, p=0.01]. Mode 3, describing decreased vertebral height was positively associated with osteoporosis [OR 1.40 95% CI 1.14–1.73, p=0.001]. Conclusion. Menopause and parity were associated with a curvier lumbar spine and osteoporosis with decreased vertebral height. Shape was not associated with back pain. No conflicts of interest.  . Sources of funding. Wellcome Trust collaborative award ref 209233

Previous studies have highlighted differences in the risk of periprosthetic fracture between tapered slip (TS) and composite beam (CB) stems. This biomechanical study explored periprosthetic fractures around these stems and the effect of adding a 16-gauge calcar or diaphyseal wire to TS stems on their resistance to torque. A power analysis determined a sample size of 7 specimens per group, assuming a standard deviation of 14.8 Nm in peak torque, to provide 90% power to detect a difference of at least 30 Nm between groups. Twenty-one TS stems (eight alone, six with calcar wiring, seven with diaphyseal wiring placed 2 cm distal to the lesser trochanter) and seven CB stems were cemented into standard Sawbones. A servo-hydraulic test machine applied a 1000 N load with a 1-degree rotation per second until failure. The peak torque at failure was measured, and the fracture location recorded. Comparisons were performed using two-sample t-tests. CB stems exhibited a significantly higher peak torque at failure (205.3 Nm) than TS stems (159.5 Nm, p=0.020). Calcar-wire-TS (148.2 Nm, p=0.036) and diaphyseal-wire-TS (164.9 Nm, p=0.036) were both weaker than CB stems. Wired-TS stems showed no significant difference from non-wired-TS stems. Additionally, the study could not conclude that calcar wiring is stronger than diaphyseal wiring. All TS fractures occurred at the mid-stem, simulating a B-type fracture, while the addition of the diaphyseal wire shifted the fracture location more distally in four of seven stems (p=0.0699). This biomechanical study supports the clinical evidence that CB stems have stronger resistance to torque than TS stems and may explain lower risk of periprosthetic fracture. The addition of calcar or diaphyseal wires to TS stems resulted in no significant changes in peak torque to fracture. In patients at high risk of periprosthetic fracture, CB cemented stems should be considered

Background. Artificial total knee designs have revolutionized over time, yet 20% of the population still report dissatisfaction. The standard implants fail to replicate native knee kinematic functionality due to mismatch of condylar surfaces and non-anatomically placed implantation. (Daggett et al 2016; Saigo et al 2017). It is essential that the implant surface matches the native knee to prevent Instability and soft tissue impingement. Our goal is to use computational modeling to determine the ideal shapes and orientations of anatomically-shaped components and test the accuracy of fit of component surfaces. Methods. One hundred MRI scans of knees with early osteoarthritis were obtained from the NIH Osteoarthritis Initiative, converted into 3D meshes, and aligned via an anatomic coordinate system algorithm. Geomagic Design X software was used to determine the average anterior-posterior (AP) length. Each knee was then scaled in three dimensions to match the average AP length. Geomagic's least-squares algorithm was used to create an average surface model. This method was validated by generating a statistical shaped model using principal component analysis (PCA) to compare to the least square's method. The averaged knee surface was used to design component system sizing schemes of 1, 3, 5, and 7 (fig 1). A further fifty arthritic knees were modeled to test the accuracy of fit for all component sizing schemes. Standard deviation maps were created using Geomagic to analyze the error of fit of the implant surface compared to the native femur surface. Results. The average shape model derived from Principal Component Analysis had a discrepancy of 0.01mm and a standard deviation of 0.05mm when compared to Geomagic least squares. The bearing surfaces showed a very close fit within both models with minimal errors at the sides of the epicondylar line (fig 2). The surface components were lined up posteriorly and distally on the 50 femurs. Statistical Analysis of the mesh deviation maps between the femoral condylar surface and the components showed a decrease in deviation with a larger number of sizes reducing from 1.5 mm for a 1-size system to 0.88 mm for a 7-size system (table 1). The femoral components of a 5 or 7-size system showed the best fit less than 1mm. The main mismatch was on the superior patella flange, with maximum projection or undercut of 2 millimeters. Discussion and Conclusion. The study showed an approach to total knee design and technique for a more accurate reproduction of a normal knee. A 5 to 7 size system was sufficient, but with two widths for each size to avoid overhang. Components based on the average anatomic shapes were an accurate fit on the bearing surfaces, but surgery to 1-millimeter accuracy was needed. The results showed that an accurate match of the femoral bearing surfaces could be achieved to better than 1 millimeter if the component geometry was based on that of the average femur. For any figures or tables, please contact the authors directly

To investigate whether anterior pelvic plane-pelvic tilt (APP-PT) is associated with distinct hip pathomorphologies, we asked: (1) Is there a difference in APP-PT between symptomatic young patients eligible for joint preservation surgery and an asymptomatic control group? (2) Does APP-PT vary between distinct acetabular and femoral pathomorphologies? (3) Does APP-PT differ in symptomatic hips based on demographic factors?. IRB-approved, single-center, retrospective, case-control, comparative study in 388 symptomatic hips (357) patients (mean age 26 ± 2 years [range 23 to 29], 50% females) that presented to our tertiary center for joint preservation over a five year-period. Patients were allocated to 12 different morphologic subgroups. The overall study group was compared to a control group of 20 asymptomatic hips (20 patients). APP-PT was assessed in all patients based on AP pelvis X-rays using the validated HipRecon software. Values between overall and control group were compared using an independent samples t-test. Multiple regression analysis was performed to examine the influences of diagnoses and demographic factors on APP-PT. Minimal clinically important difference (MCID) of APP-PT was defined as >1 standard deviation. No significant differences in APP-PT between the control group and overall group (1.1 ± 3.0° [−4.9 to 5.9] vs 1.8 ± 3.4° [−6.9 to 13.2], p = 0.323) were observed. Acetabular retroversion and overcoverage groups showed higher APP-PT compared to the control group (both p < 0.05) and were the only diagnoses with significant influence on APP-PT in the stepwise multiple regression analysis. However, all observed differences were below the MCID. Demographic factors age, gender, height, weight and BMI showed no influence on APP-PT. APP-PT across different hip pathomorphologies showed no clinically significant variation. It does not appear to be a relevant contributing factor in the evaluation of young patients eligible for hip preservation surgery

Restoration a joint's articular surface following degenerative or traumatic pathology to the osteochondral unit pose a significant challenge. Recent advances have shown the utility of collagen-based scaffolds in the regeneration of osteochondral tissue. To provide these collagen scaffolds with the appropriate superstructure novel techniques in 3D printing have been investigated. This study investigates the use of polyɛ-caprolactone (PCL) collagen scaffolds in a porcine cadaveric model to establish the stability of the biomaterial once implanted. This study was performed in a porcine cadaveric knee model. 8mm defects were created in the medial femoral trochlea and repaired with a PCL collagen scaffold. Scaffolds were secured by one of three designs; Press Fit (PF), Press Fit with Rings (PFR), Press Fit with Fibrin Glue (PFFG). Mobilisation was simulated by mounting the pig legs on a continuous passive motion (CPM) machine for either 50 or 500 cycles. Biomechanical tensile testing was performed to examine the force required to displace the scaffold. 18 legs were used (6 PF, 6 PFR, 6 PFFG). Fixation remained intact in 17 of the cohort (94%). None of the PF or PFFG scaffolds displaced after CPM cycling. Mean peak forces required to displace the scaffold were highest in the PFFG group (3.173 Newtons, Standard deviation = 1.392N). The lowest peak forces were observed in the PFR group (0.871N, SD = 0.412N), while mean peak force observed in the PF group was 2.436N (SD = 0.768). There was a significant difference between PFFG and PFR (p = 0.005). There was no statistical significance in the relationship between the other groups. PCL reinforcement of collagen scaffolds provide an innovative solution for improving stiffness of the construct, allowing easier handling for the surgeon. Increasing the stiffness of the scaffold also allows press fit solutions for reliable fixation. Press fit PCL collagen scaffolds with and without fibrin glue provide dependable stability. Tensile testing provides an objective analysis of scaffold fixation. Further investigation of PCL collagen scaffolds in a live animal model to establish quality of osteochondral tissue regeneration are required

To characterize the microstructural organization of collagen fibers in human medial menisci and the response to mechanical loading in relation to age. We combine high resolution imaging with mechanical compression to visualize the altered response of the tissue at the microscale. Menisci distribute the load in the knee and are predominantly composed of water and specifically hierarchically arranged collagen fibers. Structural and compositional changes are known to occur in the meniscus during aging and development of osteoarthritis. However, how microstructural changes due to degeneration affect mechanical performance is still largely unknown [1]. Fresh frozen 4 mm Ø plugs of human medial menisci (n=15, men, 20-85 years) with no macroscopic damage nor known diseases from the MENIX biobank at Skåne University Hospital were imaged by phase contrast synchrotron tomography at the TOMCAT beamline (Paul Scherrer Institute, CH). A rheometer was implemented into the beamline to perform in-situ stress relaxation (2 steps 15% and 30% strain) during imaging (21 keV, 2.75μm pixel size). 40s scans were acquired before and after loading, while 14 fast tomographs (5s acquisitions) were taken during relaxation. The fiber 3D orientations and structural changes during loading were determined using a structure tensor approach (adapting a script from [1]). The 3D collagen fiber orientation in menisci revealed alternating layers of fibers. Two main areas are shown: surfaces and bulk. The surface layers are a mesh of randomly oriented fibers. Within the bulk 2-3 layers of fibers are visible that alternate about 30° to each other. Structural degeneration with age is visible and is currently being quantified. During stress-relaxation all menisci show a similar behavior, with samples from older donors being characterized by larger standard deviation Furthermore, the behavior of the different layers of fibers is tracked during relaxation showing how fibers with different orientation respond to the applied loading. Acknowledgments: We thank PSI for the beamtime at the TOMCAT beamline X02DA, and funding from Swedish Research Council (2019-00953), under the frame of ERA PerMed, and the Novo Nordisk Foundation through MathKOA (NNF21OC0065373)

Abstract. Introduction. Tibial tubercle osteotomy (TTO) is a complex surgical procedure with a significant risk of complications, which include nonunion and tibial fracture. To determine whether an additional suture tape augmentation can provide better biomechanical stability compared with standard screw fixation. Methods. Five matched pairs of human cadaveric knees were divided into 2 groups: the first group underwent standard TTO fixation with 2 parallel screws. The second group underwent a novel fixation technique, in which a nonabsorbable suture tape (FiberTape) in a figure-of-8 construct was added to the standard screw fixation. Tubercular fragment migration of >50% of the initial distalization length was defined as clinical failure Tubercular fragment displacement during cyclic loading and pull-to-failure force were recorded and compared between the 2 groups. Results. The augmented group showed less cyclic tubercular fragment displacement after every load level compared with the standard group, with statistically significant differences starting from 500 N (P < .05; power > 0.8). Mean ± standard deviation tubercular fragment displacement at the end of cyclic loading was 2.56 ± 0.82 mm for the augmented group and 5.21 ± 0.51 mm for the standard group. Mean ultimate failure load after the pull-to-failure test was 2475 ± 554 N for the augmented group and 1475 ± 280 N for the standard group. Conclusion. The specimens that underwent suture tape augmentation showed less tubercular fragment displacement during cyclic loading and higher ultimate failure forces compared with those that underwent standard screw fixation

Whilst lateral ankle sprain is often considered a benign injury it represents between 3–5% of all A&E visits in the UK. The mechanical characteristics of ankle ligaments under sprain-like conditions are scarcely reported. The lateral collateral ankle ligaments were dissected from n=6 human cadaveric specimens to produce individual bone-ligament-bone specimens. An Instron Electropuls E10000 was used to uni-axially load the ankle ligaments in tension. The ligaments were first preconditioned between 2 N and a load value corresponding to 3.5% strain for 15 cycles and then strained to failure at a rate of 100%/s. The mean ultimate failure loads and their standard deviations for the anterior talofibular (ATFL), calcaneofibular (CFL) and posterior talofibular (PTFL) ligaments are 351.4±105.6 N, 367.8±76.1 N and 263.6±156.6 N, respectively. Whilst the standard deviation values are high they align with those previously reported for ankle ligament characterisation. The large standard deviations are partly due to the inherent variability of human cadaveric tissue but could also be due to varying previous activity levels of participants or a prior unreported ankle sprain. Although the sample size is relatively small the results were stratified to identify any potential correlations of age, BMI and weight with ultimate load. A strong Pearson correlation (r=0.919) was found between BMI and ultimate load of the CFL but a larger sample size is required to confirm a link. The ligament failure modes were observed and categorised as avulsion or intra-ligamentous failure. The ATFL avulsed from the fibula in five instances and intra-ligamentous failure occurred once. The CFL avulsed from the fibula twice and failed four times through intra-ligamentous failure. Finally, the PTFL avulsed from the fibula once, avulsed from the talus once and failed through intra-ligamentous failure in four instances. The results identify the forces required to severely sprain the lateral collateral ankle ligaments and their failure modes

Abstract. Objectives. The syndesmosis joint, located between the tibia and fibula, is critical to maintaining the stability and function of the ankle joint. Damage to the ligaments that support this joint can lead to ankle instability, chronic pain, and a range of other debilitating conditions. Understanding the kinematics of a healthy joint is critical to better quantify the effects of instability and pathology. However, measuring this movement is challenging due to the anatomical structure of the syndesmosis joint. Biplane Video Xray (BVX) combined with Magnetic Resonance Imaging (MRI) allows direct measurement of the bones but the accuracy of this technique is unknown. The primary objective is to quantify this accuracy for measuring tibia and fibula bone poses by comparing with a gold standard implanted bead method. Methods. Written informed consent was given by one participant who had five tantalum beads implanted into their distal tibia and three into their distal fibula from a previous study. Three-dimensional (3D) models of the tibia and fibula were segmented (Simpleware Scan IP, Synopsis) from an MRI scan (Magnetom 3T Prisma, Siemens). The beads were segmented from a previous CT and co-registered with the MRI bone models to calculate their positions. BVX (125 FPS, 1.25ms pulse width) was recorded whilst the participant performed level gait across a raised platform. The beads were tracked, and the bone position of the tibia and fibula were calculated at each frame (DSX Suite, C-Motion Inc.). The beads were digitally removed from the X-rays (MATLAB, MathWorks) allowing for blinded image-registration of the MRI models to the radiographs. The mean difference and standard deviation (STD) between bead-generated and image-registered bone poses were calculated for all degrees of freedom (DOF) for both bones. Results. The absolute mean tibia and fibula bone position differences (Table 1) between the bead and BVX poses were found to be less than 0.5 mm for both bones. The bone rotation differences were found to be less than 1° for all axes except for the fibula Z axis rotation which was found to be 1.46°. One study. 1. has reported the kinematics of the syndesmosis joint and reported maximum ranges of motion of 9.3°and translations of 3.3mm for the fibula. The results show that the accuracy of the methodology is sufficient to quantify these small movements. Conclusions. BVX combined with MRI can be used to accurately measure the syndesmosis joint. Future work will look at quantifying the accuracy of the talus to provide further understanding of normal ankle kinematics and to quantify the kinematics across a healthy population to act as a comparator for future patient studies. Declaration of Interest. (b) declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research reported:I declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project

Introduction. Achieving high flexion after total knee arthroplasty is very important for patients in Asian countries where deep flexion activities are an important part of daily life. The Bi-Surface Total Knee System (Japan Medical Material, Kyoto, Japan), which has a unique ball-and-socket mechanism in the mid-posterior portion of the femoral and tibial components, was designed to improve deep knee flexion and long-term durability after total knee arthroplasty (Figure 1). The purpose of this study was to determine the in vivo three dimensional kinematics of Bi-Surface Total Knee System in order to evaluate and analyze the performance of this system with other conventional TKA designs currently available in the market today. Materials and Methods. Three dimensional kinematics were evaluated during a weight-bearing deep knee bend activity using fluoroscopy and a 2D-to-3D registration technique for 66 TKA. Each knee was analyzed to determine femorotibial kinematics, including weight-bearing range of motion, anterior/posterior contact position, and tibio-femoral rotation. Results. The average weight-bearing range of motion for the entire group was 125.5∗∗∗∗∗. Forty three of sixty six knees had greater range of motion than 120∗∗∗∗∗. At full extension, the average contact positions were −0.5mm (range, from −12.2mm to 6.8mm; standard deviation 3.5mm), and −3.8mm (range, from −14.1mm to 6.0mm; standard deviation 4.9mm) for the medial compartment and the lateral compartment, respectively. At maximum flexion, the average contact position was −9.2mm (range, from −17.8mm to 2.4mm; standard deviation 3.7mm), and −14.8mm (range, from −20.1mm to 5.7mm; standard deviation 2.7mm) for the medial compartment and the lateral compartment, respectively (Figure 2). From full extension to maximum flexion, the average posterior femoral rollback observed was −8.7mm (range, from −22.1mm to 1.0mm; standard deviation 4.3mm) for the medial compartment, and −11.0mm (range, from −21.9mm to 6.6mm; standard deviation 5.4mm) for the lateral compartment. At full extension, the average axial orientation was 3.8∗∗∗∗∗ (range, from −5.3∗∗∗∗∗ to 26.4∗∗∗∗∗; standard deviation 5.2∗∗∗∗∗) of external femoral rotation. At maximum flexion, the average axial orientation was 9.5∗∗∗∗∗ (range, from −5.9∗∗∗∗∗ to 27.7∗∗∗∗∗; standard deviation 6.7∗∗∗∗∗). Therefore, from full extension to maximum flexion, the average amount of axial rotation was 5.7∗∗∗∗∗ (range, from −15.1∗∗∗∗∗ to 22.2∗∗∗∗∗; standard deviation 6.4∗∗∗∗∗). Discussion. The Bi-Surface Knee System was designed to accommodate the life style led by Asian populations, by aiming to improve both, knee flexion and long-term durability. Though durability of the device is beyond the scope of this study, subjects in this study did achieve high weight-bearing flexion, excellent posterior femoral rollback of both condyles and a normal axial rotation patterns, albeit, less than the normal knee. Also, this is the first in vivo study conducted to understand the kinematic patterns generated for subject implanted with this device. The amount of posterior rollback and axial rotation were found to be similar in nature to the normal knee as well as other established TKA devices available for implantation today, but again less than the normal knee

Introduction. Removal of primary components during revision TKA procedure can damage underlying bone, resulting in defects that may need filled for stability of the revision reconstruction. Special revision components including cones and/or augments are often used to compensate for the missing bones. Little work has been done to characterize metaphyseal geometry in the vicinity of the knee joint, however, in order to motivate proper size and shape of cones and augments. The objective of this study was to use statistical shape modelling to evaluate variation in endosteal anatomy for revision TKA. Methods. Digital models of the femur and tibia were generated through segmentation of computed tomography scans, for the femur and the tibia (n∼500). Custom software was used to perform virtual surgery and statistical shape analysis of the metaphyseal geometry. A representative and appropriately sized revision femoral component was placed on each bone, assuming anterior referencing with an external rotation of 3 degrees from the posterior condyle axis. The outer and inner boundaries of the cortical bone were determined at the resection level and at 5 mm increments proximally, up to 40 mm. Similar analyses were performed on the tibia, using a typical revision resection (0 degrees medial and posterior slope), with outer and inner boundaries of the cortical bone were determined in 5 mm increments up to 40mm distal to the resection. Metaphyseal contours were exported relative to the central fixation feature of the implant, and average geometries were calculated based on size, and across the entire cohort. Principal Component Analysis (PCA) was used to quantify the variability in shape, specifically to evaluate the +/− 1 and 2 standard deviation geometries at each cross section level of Principal Component 1 (PC1). Results. Representative results illustrating the effect of size for the femur at single depth and the effect of depth and PC1 for tibia are reported. The average inner metaphyseal geometry of the femur (30mm proximal to resection) varied from 25.1×47.7 mm (AP x ML) at the smallest size to 54.5×78.0 at the largest size. The overall average tibia geometry decreased from 51.5×69.5 mm at the base resection level to 33.5×31.3 mm at the most distal resection level (40mm) distal to the resection. At the 20 mm level, the average tibia contour of 45.0×47.8 mm changed to 32.2×33.4 at −2 standard deviations of PC1 and 57.9×62.4 mm at the +2 standard deviations of PC1. Discussion. The generated contours can be used as a design input to optimize the shape of cones and augments, in order to fit potential defects in the femur and tibia encountered during revision TKA while respecting the anatomical constraints of the bone. Statistical shape analysis shows that these constraints are not strictly uniform scaling, based on bone size or on location in the metaphysis, but rather reflect variations in shape that may be used to optimize fit and stability of the prostheses