Aims. 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. Methods. Patients undergoing primary THA at our institution with an OHS both preoperatively and at least four years postoperatively were included. Rationing thresholds were explored to identify possible deprivation of OHS improvement. Results. Overall, 2,341 patients were included. Mean OHS was 19.7 (SD 8.2) preoperatively and 39.7 (SD 9.8) at latest follow-up. An improvement of at least eight-points, the minimally important change (MIC), was seen in 2,072 patients (88.5%). The mean improvement was 20.0 points (SD 10.5). If a rationing threshold of OHS of 20 points had been enforced, 90.8% of those treated would have achieved the MIC, but only 54.3% of our cohort would have had access to surgery; increasing this threshold to 32 would have enabled 89.5% of those treated to achieve the MIC while only depriving 6.5% of our cohort. The ‘rationed’ group of OHS > 20 had significantly better OHS at latest follow-up (42.6 vs 37.3; p < 0.001), while extending the rationing threshold above 32 showed postoperative scores were more significantly affected by the ceiling effect of the OHS. Conclusion. The OHS was not designed as a tool to ration healthcare, but if it had been used at our institution for this cohort, applying an OHS threshold of 20 to routine THA access would have excluded nearly half of patients from having a THA; a group in which over 85% had a significant improvement in OHS. Where its use for rationing is deemed necessary, use of a higher threshold may be more appropriate to ensure a better balance between patient access to treatment and chances of achieving good to excellent outcomes. Cite this article: Bone Jt Open 2022;3(3):196–204

Mechanical irritation or impingement of the iliopsoas tendon accounts for 2–6% of persistent postoperative pain cases after total hip arthroplasty (THA). The most common trigger is anterior cup overhang. CT-scan can be used to identify and measure this overhang; however, no threshold exists for symptomatic anterior iliopsoas impingement. We conducted a case–control study in which CT-scan was used to define a threshold that differentiates patients with iliopsoas impingement from asymptomatic patients after THA. We analyzed the CT-scans of 622 patients (758 CT-scans) between 2011 and 2020. Out of this population we identified 136 patients with symptoms suggestive of iliopsoas impingement. Among them, 6 were subsequently excluded: three because the diagnosis was reestablished intra-operatively (one metallosis, two anterior instability related to posterior prosthetic impingement) and three because they had another obvious cause of impingement (one protruding screw, one protruding cement plug, one stem collar), leaving 130 patients in the study (impingement) group. They were matched to a control group of 138 patients who were asymptomatic after THA. The anterior cup overhang (anterior margin of cup not covered by anterior wall) was measured by an observer (without knowledge of the clinical status) on an axial CT slice based on anatomical landmarks (orthogonal to pelvic axis). The impingement group had a median overhang of 8 mm [IQR: 5 to 11] versus 0 mm [IQR: 0 to 4] for the control group (p<.001). Using ROC curves, an overhang threshold of 4 mm was best correlated with a diagnosis of impingement (sensitivity 79%, specificity 85%, PPV = 75%, NPV = 85%). Pain after THA related to iliopsoas impingement can be reasonably linked to acetabular overhang if it exceeds 4 mm on a CT scan. Below this threshold, it seems logical to look for another cause of iliopsoas irritation or another reason for the pain after THA before concluding impingement is present

Purpose of study and background. Psychological factors are considered to play a role in development and maintenance of chronic low back pain (CLBP). Stress or anxiety can change pain sensitivity; however, this has predominantly been studied in healthy individuals with limited work in individuals with musculoskeletal pain. The objective of this study was to quantify the effect of acute exposure to a psychosocial stressor on mechanical pain sensitivity in individuals with and without CLBP. Summary of methods and results. Six individuals with CLBP and 10 individuals without CLBP performed a 10-minute computer task under conditions of low and high psychosocial stress. Psychosocial stress was manipulated using mental maths and memory tasks combined with social evaluative threat. The effect of the stressor was evaluated using blood pressure, heart rate and the state anxiety component of the Spielberger State-Trait Anxiety Index. Mechanical pressure pain threshold (PPT) was recorded on the tibialis anterior muscle using a handheld digital pressure algometer. The stress manipulation increased self-reported anxiety (p<0.001), but not blood pressure or heart rate (p>0.06). Change in PPT from low to high stress was greater in the CLBP group (median ΔPPT = −0.5 kg/cm. 2. ) than in the control group (−0.15 kg/cm. 2. ; p=0.005). Conclusion. Individuals experienced an increase in pain sensitivity after acute exposure to a stressor designed to mimic low-level workplace stressors, and this increase was greater in individuals with CLBP than asymptomatic individuals. These results indicate that this experimental model can be used to study links between pain sensitivity and psychosocial stressors and increase our understanding of their potential role in CLBP. Conflicts of Interest: No conflicts of interest. Sources of funding: No funding obtained

The process of femoral impaction grafting requires vigorous impaction to obtain adequate stability but the force of impaction has not been determined. This process has been reported to result in femoral fractures with rates reaching 16%. The aims of this study were to determine the threshold force required for femoral impaction grafting, to determine the affect cortical thickness, canal diameter and bone mineral density (BMD) have on this threshold force and to measure subsidence of an Exeter prosthesis following impaction at the threshold force. Adult sow femurs were prepared and placed through a DEXA scanner and the BMD and canal diameter measured. Thirty five femurs were impacted with morsellised bone chips and an increasing force of 0.5kN was applied until the femur fractured. Using callipers the cortical thickness of the bone was measured along the fracture line. Once the threshold force was determined 5 femurs were impacted to this threshold force and an Exeter stem was cemented into the neomedullary canal and a 28mm Exeter head attached. Axial cyclic loading was performed between 440N (swing phase of gait) and 1320N (stance phase of gait) for 150,000 cycles at a frequency of 3Hz. The position sensor of the hydraulic testing machine measured the subsidence. 29 tests were successfully completed. The threshold force was found to be 4kN. There was no significant correlation between the load at fracture and the cortex: canal ratio or the bone mineral density. Following impaction with the maximum force of 4kN the average subsidence for the 5 femurs was 0.276mm (range 0.235 – 0.325mm). In this animal study the threshold force was 4kN. Minimal axial subsidence of the implant occurred when impacting the graft with this threshold force. We therefore achieved a stable construct without fracture which is the ultimate goal for the revision hip surgeon

Introduction: Sensory hypersensitivity, central hyper-excitability (lowered nociceptive flexion reflex (NFR) thresholds) and psychological distress are features of chronic whiplash. Relationships between these substrates are not clear. The aim of this study was to investigate relationships between psychological factors (distress, catastrophization) and pain threshold responses to sensory stimuli and spinal cord excitability as assessed by the NFR. The former assessments are considered as global pain responses to sensory stimuli as reported by the patient, whereas the latter, an objective measurement for spinal cord excitability to peripheral stimulation. Methods: 30 individuals with chronic (> 3 months) whiplash (Grade II or III; Grade IV were excluded) and 30 asymptomatic controls participated. Pressure pain thresholds (PPTs) and thermal pain thresholds (Thermotest, Somedic AB, Sweden) were measured at the cervical spine, upper and lower limbs. The NFR (intensity of electrical stimulation at the sural nerve required to elicit reflex EMG activity of biceps femoris) was measured as per previous protocols (1). Pain and disability levels (NDI), psychological distress (GHQ-28) and catastrophisation (PCS) were also measured in the whiplash group. Ethical clearance for this study was granted by the Medical Research Ethics Committee of the University of Qld. A MANCOVA was used to determine differences between the whiplash group and controls for sensory measures and the NFR. GHQ-28 and PCS scores were used as covariates in the analysis. Group differences for questionnaire data (GHQ-28 and PCS) were analysed using one way ANOVA. Pearson’s correlation coefficients were used to determine the relationship between the psychological measures (PCS and GHQ-28), pain and disability levels (NDI) and the pain threshold measures (mechanical and thermal) and to determine relationships between the psychological measures, pain and disability measures (NDI) and NFR responses (pain intensity at threshold, threshold). p< 0.05. Results: Whiplash injured participants (23 females, mean (SD) age: 37.7 (11.5) years, NDI: 46.2 (17.6) and VAS scores of pain: 4.2 (2.4)) demonstrated lowered pain thresholds to pressure and cold (p< 0.05); lowered NFR thresholds (p=0.003) and above threshold levels of psychological distress (GHQ-28) compared to controls and levels of catastrophisation comparable to other musculoskeletal conditions. There were no group differences for heat pain thresholds or pain at NFR threshold. In the whiplash group, PCS scores correlated moderately with cold pain threshold (r =0.51, p=0.01). In contrast there were no significant correlations between GHQ-28 scores and pain threshold measures or between psychological factors and NFR responses in whiplash participants. There were no significant correlations between psychological factors and pain thresholds or NFR responses in controls. Discussion: We have demonstrated that psychological factors have some association with sensory hypersensitivity (cold pain threshold measures) in chronic whiplash but do not seem to influence spinal cord excitability. This suggests that psychological disorders are important, but not the only, determinants of central hypersensitivity in whiplash patients. These findings suggest that both physical and psychological factors will need to be addressed in the management of whiplash

The threshold for decompression in acute compartment syndrome is quoted as a pressure difference between the compartment and diastolic blood pressure of less than 30mmHg. This study reports the findings of continuous compartment pressure monitoring in children who underwent tibial osteotomies. In this prospective observational study, twenty seven children who underwent tibial osteotomies had anterior compartment pressures monitored using a transducer-tipped probe for a minimum of 72 hours following surgery. Pressure data were collected hourly together with evidence of clinical signs, symptoms and patterns of analgesic use. Patients were also reviewed for late sequelae of compartment syndrome. One case of compartment syndrome were encountered. Pressure differences (diastolic BP - compartment pressure) were found to vary widely, with many children exceeding the threshold for decompression but without manifesting other signs of compartment syndrome. Fasciotomies were not performed in view of the conflicting evidence and subsequent review confirmed the absence of late sequelae. In these children, low diastolic blood pressures were a common but normal feature. The prevalence of compartment syndrome was 3.7% (1/27). The positive predictive value of using the adult threshold was 7.1%; the negative predictive value was 100%. We conclude that the threshold for decompression as applied to adults is unsuitable for use in children inasmuch as a positive result would lead to a correct diagnosis in only 7.1% of children. A negative test is more useful in correctly excluding compartment syndrome in 100% of the children studied

Background: Quantitative sensory testing (QST) conventionally identifies threshold elevation as reflecting sensory deficit. A major disadvantage of the technique is its inability to distinguish organic from feigned sensory deficit, as both are characterized by an elevated threshold. Aim: To distinguish organic from feigned sensory deficit. Method: Vibratory thresholds and their variances were measured, at foot L4, L5 and S1 sites, in 14 patients with low back pain (LBP) suspected of non-organic sensory loss by clinical criteria of Waddell, 14 patient controls with abnormal neurological examination and CT of the low back, and 20 healthy controls. Results: Thresholds of non-organic patients and of patient controls were elevated to a similar extent compared to those of healthy controls. Variances, however, were higher for non-organic patients (6.7–10.5 for the various test sites) than for either patient controls (0.39–0.80, p: 0.001–0.05) or for healthy controls (0.20–0.54, p: 0.001–0.02). Of non-organic patients with high thresholds who would otherwise be identified as pathological, 30–67% were ‘spared’ the misdiagnosis and correctly identified as non-organic because of the inclusion of the variance criterion. Conclusion: Variance evaluation is therefore suggested for inclusion into QST methodology, together with threshold itself, as a quality assurance parameter

Serological tests including erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) are frequently used in the preoperative workup to screen for periprosthetic infection (PPI) in total hip arthroplasty (THA). The cut-off points reported in the literature are arbitrarily chosen by investigators. Similarly, the values used in laboratories to distinguish elevated results vary from one institute to another. Therefore, we intended to define the appropriate cut-off points of ESR and CRP that can be used to differentiate infection from aseptic failure of THA. A review of our joint registry database revealed that 515 THA revisions (131 infected cases) were performed during 2000–2005. Intraoperative samples for culture were taken in all cases. The criteria used for diagnosis of infection were a positive intraoperative culture on solid media, presence of an abscess or sinus tract that communicated with the joint, positive preoperative aspiration culture, and/or elevated fluid cell count and neutrophil differential of the aspirated fluid. Non-infected patients with confounding factors that can elevate ESR and CRP including collagen vascular disease, inflammatory arthropathy, malignancy, and urinary tract infection were excluded. Receiver operator curves were used to determine the ideal cut-off point for both ESR and CRP. The mean value of ESR in the infected group (77mm/ hr) was significantly higher compared to that of the non-infected cohort (29mm/hr) (p=0.0001). Similarly, infected patients presented with a greater mean CRP (9.8 mg/dl) than their non-infected cohort (1.48 mg/ dl) (p=0.0001). The infection threshold for ESR was 45mm/hr with a sensitivity of 85% and specificity of 79%, while the optimal cut-off value for CRP was defined as 1.6 mg/dl which yielded a sensitivity of 86% and specificity of 83%. The optimal threshold values we determined are higher than the arbitrarily chosen values cited in the literature for ESR (30mm/hr) and CRP (1mg/dl). Although it has been previously reported that the sensitivity and specificity of CRP are far greater than that of ESR, we found that the two tests have comparable diagnostic value

The aim was to determine reliability in treatment threshold based on USS angular measurements between observers involved in the DDH hip screening programme at the NOC and assess the effect of image orientation on the accuracy of these measurements. 3 independent observers measured alpha and beta angles on bilateral hips in 10 consecutive patients seen in the DDH hip screening clinic. All scans were performed by a single radiographer and observers used the same set of USS images for a given patient. Each observer measured alpha and beta angles a total of 4 times: conventional ultrasound image projection (with the ilium horizontal) (round 1), Graf's anatomical projection (round 2), and both techniques repeated 1 month later (round 3 and 4 respectively) to assess intra-observer reliability. To determine its effect on treatment threshold taking into account alpha and beta angles and patient's age, the consistency between observers' management recommendations was evaluated for each round. Possible outcomes were: 1) patient discharged, 2) no treatment needed yet, but follow-up required, 3) start treatment. Intra-observer reliability for conventional projection was moderate (Kappa 0.58), and improved for anatomical projection (Kappa 0.65). Inter-observer reliability, as a surrogate measure of consistency in management recommendations between observers, ranged from fair to moderate across the 4 rounds (Kappa 0.30 – 0.50). However, contrary to previous recommendations, reliability was better with conventional projection (Kappa 0.41 (95% CI 0.11–0.72)) compared to anatomical projection (Kappa 0.36 (95% CI −0.01–0.73)). The overall agreement in management recommendations, pooling all results across 4 rounds, was 51.3% (Kappa 0.39 (95%CI 0.15–0.63)). This audit supports the argument that anatomical image projection improves intra-observer consistency. However, as with all USS measurements, angular measurements were highly user dependent and treatment threshold based on USS may not be as consistent as anticipated

It has been suggested that metal ion level elevations in certain bilateral MM bearing arthroplasties were overwhelming the renal threshold for metal excretion leading to systemic build-up of metal ions above the expected levels. In order to investigate this we studied renal concentrating efficacy through concurrent specimens of urine and whole blood over a range of metal levels. Concurrent specimens from 305 unselected patients were obtained. They include preoperative patients (76) and those with unilateral and bilateral hip arthroplasties (229) through to ten years after operation. 39 pre-operative specimens and 4 follow-up specimens had blood levels at or below the detection limit for cobalt or chromium and were excluded. The ratio of urine to whole blood concentration was 0.78 in the pre-operative patients. In patients with MM arthroplasties the different ratios in patients increased (from 3.1 to 9.2) with increasing urine concentrations. The ratio of urine cobalt concentration to blood cobalt concentration is a measure of renal concentrating efficacy. Amongst pre-operative controls, this ratio is 0.78, indicating that there is renal conservation of cobalt. In terms of cobalt, these patients’ urine was dilute in comparison to whole blood. In patients with MM bearings, the ratio went up to 4.8 indicating that the kidneys were now actively excreting against a concentration gradient in an attempt to maintain internal milieu. If renal threshold was being breached at higher levels, then the ratio should progressively fall at higher concentrations. The trend in this experiment shows quite the contrary effect and the ratio reached 9.2 in those with urine cobalt > 15 μg/l, demonstrating that renal clearance efficiency holds up even against this steep gradient and that the threshold is not breached within clinically relevant levels

Although wait-times for hip fracture surgery have been linked to mortality and are being used as quality-of-care indicators worldwide, controversy exists about the duration of the wait that leads to complications. Our objective was to use new population-based wait-time data to emprically derive an optimal time window in which to conduct hip fracture surgery before the risk of complications increases. We used health administrative data from Ontario, Canada to identify hip fracture patients between 2009 and 2014. The main exposure was the time from hospital arrival to surgery (in hours). The primary outcome was mortality within 30 days. Secondary outcomes included a composite of mortality or other medical complications (MI, DVT, PE, and pneumonia) also within 30 days. Risk-adjusted cubic splines modeled the probability of each complication according to wait-time. The inflection point (in hours) when complications began to increase was used to define ‘early’ and ‘delayed’ surgery. To evaluate the robustness of this definition, outcomes amongst propensity-score matched early and delayed patients were compared using percent absolute risk differences (% ARDs, with 95% confidence intervals [CIs]). There were 42,230 patients who met entry criteria. Their mean age was 80.1 (±10.7) and the majority were female (70.5%). The risk of complications modeled by cubic splines consistently increased when wait-times were greater than 24 hours, irrespective of the complication considered. Compared to 13,731 propensity-score matched patients who received surgery earlier, 13,731 patients receiving surgery after 24 hours had a significantly higher risk of 30-day mortality (N=898 versus N=790, % ARD 0.79 [95% CI 0.23 to 1.35], p = .006) and the composite outcome (N=1,680 versus N=1,383, % ARD 2.16 [95% CI 1.43 to 2.89], p < .001). Overall, there were 14,174 patients (33.6%) who received surgery within 24 hours and 28,056 patients (66.4%) who received surgery after 24 hours. Increased wait-time was associated with a greater risk for 30-day mortality and other complications. The finding that a wait-time of 24 hours represents a threshold defining higher risk may inform existing hip fracture guidelines. Since two-thirds of patients did not receive surgery within this timeframe, performance improvement efforts that reduce wait-times are warranted

Aim of the study: To calculate minimum-provider-volumes in total knee replacement by means of German routine data for the first time. Materials and methods: In patients with primary total knee replacement (TKR) the correlation between hospital volume per year and risk of “insufficient mobility” (primary quality indicator) and “wound infection” (secondary quality indicator) was calculated by means of logistic regression models based on the data of 110.349 primary total knee replacements operated in 1.016 German hospitals in 2004. Results: For both indicators a statistically significant relationship between hospital volume and outcome could be proven. Other risk factors such as age and ASA-status also had a significant influence, but did not appear as important confounders. The risk for the secondary quality indicator “infection” decreased constantly by increasing hospital volume, thus the curve was very flat. This supports the hypothesis that high volume hospitals show up to have a higher quality level than low-volume hospitals. A threshold value of 116 TKR per year (95% CI 90–141) could be calculated. However, the explanation value of the hospital volume was too low to derive a threshold level that clearly discriminates between good and bad quality of care. The relationship between the primary quality indicator “insufficient mobility” and the hospital volume unexpectedly showed a U-shaped distribution. This questions the concept of a minimum provider volume regulation for primary total knee replacement regarding the risk factor “insufficient mobility”. Therefore, in this case no quantitative threshold values were calculated. Conclusion: This analysis supports the hypothesis of a volume-outcome-relationship in primary total knee replacement. However, a minimum provider volume that clearly discriminates between good and bad quality of care could not be calculated on basis of German quality assurance data

Introduction: Algometry has been shown to be an effective way of quantifying pressure pain threshold (PPT), although it’s reliability in assessing spinal muscle pain (excluding trigger points) has not been robustly analysed. Method: Intra-rater test re-test reliability PPT assessment by algometry over the belly of four pairs of spinal muscles, (iliocostalis, multifidus, gluteus maximus and trapezius) in a healthy sample (80 assessments) was analysed. Healthy subjects were tested twice (within 15mins) on three occasions (separated by a week); 240 sets of assessments revealed good within-session reliability (ICC> .91) and good between session reliability (ICC> .87), with a relatively small measurement error (approximately 3kg/cm. 2. ) and no systematic difference within session or between sessions. Conclusion: In conclusion, PPT assessment by algometry is a reliable, both within and between sessions, measure of a subject’s pain. This study provides further validity to the use of this measure as a suitable, convenient method of monitoring treatment effects

Summary

A laboratory based study investigating fracture forces and implant subsidence rates in embalmed human femurs undergoing impaction grafting.

Background and purpose

The two most common complications of femoral impaction bone grafting are femoral fracture and massive implant subsidence. We investigated fracture forces and implant subsidence rates in embalmed human femurs undergoing impaction grafting. The study consisted of two arms, the first examining the force at which femoral fracture occurs in the embalmed human femur, and the second examining whether significant graft implant/subsidence occurs following impaction at a set force at two different impaction frequencies.

Aims. Glenoid bone loss is a significant problem in the management of shoulder instability. The threshold at which the bone loss is considered “critical” requiring bony reconstruction has steadily dropped and is now approximately 15%. This necessitates accurate measurement in order that the correct operation is performed. CT scanning is the most commonly used modality and there are a number of techniques described to measure the bone loss however few have been validated. The aim of this study was to assess the accuracy of the most commonly used techniques for measuring glenoid bone loss on CT. Methods. Anatomically accurate models with known glenoid diameter and degree of bone loss were used to determine the mathematical and statistical accuracy of six of the most commonly described techniques (relative diameter, linear ipsilateral circle of best fit (COBF), linear contralateral COBF, Pico, Sugaya, and circle line methods). The models were prepared at 13.8%, 17.6%, and 22.9% bone loss. Sequential CT scans were taken and randomized. Blinded reviewers made repeated measurements using the different techniques with a threshold for theoretical bone grafting set at 15%. Results. At 13.8%, only the Pico technique measured under the threshold. At 17.6% and 22.9% bone loss all techniques measured above the threshold. The Pico technique was 97.1% accurate, but had a high false-negative rate and poor sensitivity underestimating the need for grafting. The Sugaya technique had 100% specificity but 25% of the measurements were incorrectly above the threshold. A contralateral COBF underestimates the area by 16% and the diameter by 5 to 7%. Conclusion. No one method stands out as being truly accurate and clinicians need to be aware of the limitations of their chosen technique. They are not interchangeable, and caution must be used when reading the literature as comparisons are not reliable. Cite this article: Bone Jt Open 2023;4(7):478–489

Aims. To evaluate mid-to long-term patient-reported outcome measures (PROMs) of endoprosthetic reconstruction after resection of malignant tumours arising around the knee, and to investigate the risk factors for unfavourable PROMs. Methods. The medical records of 75 patients who underwent surgery between 2000 and 2020 were retrospectively reviewed, and 44 patients who were alive and available for follow-up (at a mean of 9.7 years postoperatively) were included in the study. Leg length discrepancy was measured on whole-leg radiographs, and functional assessment was performed with PROMs (Toronto Extremity Salvage Score (TESS) and Comprehensive Outcome Measure for Musculoskeletal Oncology Lower Extremity (COMMON-LE)) with two different aspects. The thresholds for unfavourable PROMs were determined using anchor questions regarding satisfaction, and the risk factors for unfavourable PROMs were investigated. Results. The thresholds for favourable TESS and COMMON were 64.8 and 70.4 points, respectively. Multivariate analysis showed that age at surgery (p = 0.004) and postoperative leg length discrepancy (p = 0.043) were significant risk factors for unfavourable TESS results, while age at surgery (p < 0.001) was a significant risk factor for unfavourable COMMON-LE results. Following receiver operating characteristic analysis, the threshold for both TESS and COMMON-LE was 29 years of age at surgery. Additionally, a leg length discrepancy of 8.2 mm was the threshold for unfavourable TESS. Conclusion. Patients aged > 29 years at the time of surgery require appropriate preoperative counselling and adequate postoperative physical and socioemotional support. Reconstruction equivalent to the length of the resected bone can reduce the risk of functional disabilities in daily living. Cite this article: Bone Jt Open 2023;4(12):906–913

Aims. The rationale for exacting restoration of skeletal anatomy after unstable ankle fracture is to improve outcomes by reducing complications from malunion; however, current definitions of malunion lack confirmatory clinical evidence. Methods. Radiological (absolute radiological measurements aided by computer software) and clinical (clinical interpretation of radiographs) definitions of malunion were compared within the Ankle Injury Management (AIM) trial cohort, including people aged ≥ 60 years with an unstable ankle fracture. Linear regressions were used to explore the relationship between radiological malunion (RM) at six months and changes in function at three years. Function was assessed with the Olerud-Molander Ankle Score (OMAS), with a minimal clinically important difference set as six points, as per the AIM trial. Piecewise linear models were used to investigate new radiological thresholds which better explain symptom impact on ankle function. Results. Previously described measures of RM and surgeon opinion of clinically significant malunion (CSM) were shown to be related but with important differences. CSM was more strongly related to outcome (-13.9 points on the OMAS; 95% confidence interval (CI) -21.9 to -5.4) than RM (-5.5 points; 95% CI -9.8 to -1.2). Existing malunion thresholds for talar tilt and tibiofibular clear space were shown to be slightly conservative; new thresholds which better explain function were identified (talar tilt > 2.4°; tibiofibular clear space > 6 mm). Based on this new definition the presence of RM had an impact on function, which was statistically significant, but the clinical significance was uncertain (-9.1 points; 95% CI -13.8 to -4.4). In subsequent analysis, RM of a posterior malleolar fracture was shown to have a statistically significant impact on OMAS change scores, but the clinical significance was uncertain (-11.6 points; 95% CI -21.9 to -0.6). Conclusion. These results provide clinical evidence which supports the previously accepted definitions. Further research to investigate more conservative clinical thresholds for malunion is indicated. Cite this article: Bone Jt Open 2022;3(10):841–849

Aims. The aim of this study was to produce clinical consensus recommendations about the non-surgical treatment of children with Perthes’ disease. The recommendations are intended to support clinical practice in a condition for which there is no robust evidence to guide optimal care. Methods. A two-round, modified Delphi study was conducted online. An advisory group of children’s orthopaedic specialists consisting of physiotherapists, surgeons, and clinical nurse specialists designed a survey. In the first round, participants also had the opportunity to suggest new statements. The survey included statements related to ‘Exercises’, ‘Physical activity’, ‘Education/information sharing’, ‘Input from other services’, and ‘Monitoring assessments’. The survey was shared with clinicians who regularly treat children with Perthes’ disease in the UK using clinically relevant specialist groups and social media. A predetermined threshold of ≥ 75% for consensus was used for recommendation, with a threshold of between 70% and 75% being considered as ‘points to consider’. Results. A total of 40 participants took part in the first round, of whom 31 completed the second round. A total of 87 statements were generated by the advisory group and included in the first round, at the end of which 31 achieved consensus and were removed from the survey, and an additional four statements were generated. A total of 60 statements were included in the second round and 45 achieved the threshold for consensus from both rounds, with three achieving the threshold for ‘points to consider’. The recommendations predominantly included self-management, particularly relating to advice about exercise and education for children with Perthes’ disease and their families. Conclusion. Children’s orthopaedic specialists have reached consensus on recommendations for non-surgical treatment in Perthes’ disease. These statements will support decisions made in clinical practice and act as a foundation to support clinicians in the absence of robust evidence. The dissemination of these findings and the best way of delivering this care needs careful consideration, which we will continue to explore. Cite this article: Bone Joint J 2024;106-B(5):501–507

Aims. 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). Methods. There were 3,321 patients undergoing primary TKA with preoperative and one-year postoperative SF-36 scores. At one-year patients were asked how satisfied they were and “How much did the knee arthroplasty surgery improve the quality of your life?”, which was graded as: great, moderate, little (n = 277), none (n = 98), or worse. Results. Physical function, role limitations due to physical problems (‘role physical’), bodily pain, and the total score SF-36 scores demonstrated the greatest effect sizes (> 0.9). The MCID for each of SF-36 dimensions ranged from 1.7 for role emotional to 6.4 for bodily pain. The MICs for a cohort of patients ranged from -1.0 for general health to 11.1 for bodily pain. The MICs for an individual patient were marginally greater (one to two points) compared to those for a cohort, and ranging from 0.0 for general and mental health to 13.5 for physical function. The lowest PASS score threshold was associated with physical function (> 34 points) whereas the greatest threshold (> 69 points) was associated with mental health. Conclusion. The SF-36 is a responsive tool, and the estimates for MCID, MIC, and PASS thresholds that can be used to power studies, assess whether there has been a meaningful change in patients’ health-related quality of life, and can be used as a marker of achieving patient satisfaction following TKA. Cite this article: Bone Joint Res 2022;11(7):477–483