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

Aims

The purpose of this study was to assess the reliability and responsiveness to hip surgery of a four-point modified Care and Comfort Hypertonicity Questionnaire (mCCHQ) scoring tool in children with cerebral palsy (CP) in Gross Motor Function Classification System (GMFCS) levels IV and V.

Aims

The surgical helmet system (SHS) was developed to reduce the risk of periprosthetic joint infection (PJI), but the evidence is contradictory, with some studies suggesting an increased risk of PJI due to potential leakage through the glove-gown interface (GGI) caused by its positive pressure. We assumed that SHS and glove exchange had an impact on the leakage via GGI.

Aims

Open lower limb fracture is life-changing, resulting in substantial morbidity and resource demand, while inconsistent outcome-reporting hampers systematic review and meta-analysis. A core outcome set establishes consensus among key stakeholders for the recommendation of a minimum set of outcomes. This study aims to define a core outcome set for adult open lower limb fracture.

Aims

This study aimed to evaluate the accuracy of implant placement with robotic-arm assisted total hip arthroplasty (THA) in patients with developmental dysplasia of the hip (DDH).

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

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

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

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