Aims

To systematically review qualitative studies of patients with distal tibia or ankle fracture, and explore their experience of injury and recovery.

Aims. The increase in prescription opioid misuse and dependence is now a public health crisis in the UK. It is recognized as a whole-person problem that involves both the medical and the psychosocial needs of patients. Analyzing aspects of pathophysiology, emotional health, and social wellbeing associated with persistent opioid use after injury may inform safe and effective alleviation of pain while minimizing risk of misuse or dependence. Our objectives were to investigate patient factors associated with opioid use two to four weeks and six to nine months after an upper limb fracture. Methods. A total of 734 patients recovering from an isolated upper limb fracture were recruited in this study. Opioid prescription was documented retrospectively for the period preceding the injury, and prospectively at the two- to four-week post-injury visit and six- to nine-month post-injury visit. Bivariate and multivariate analysis sought factors associated with opioid prescription from demographics, injury-specific data, Patient Reported Outcome Measurement Instrumentation System (PROMIS), Depression computer adaptive test (CAT), PROMIS Anxiety CAT, PROMIS Instrumental Support CAT, the Pain Catastrophizing Scale (PCS), the Pain Self-efficacy Questionnaire (PSEQ-2), Tampa Scale for Kinesiophobia (TSK-11), and measures that investigate levels of social support. Results. A new prescription of opioids two to four weeks after injury was independently associated with less social support (odds ratio (OR) 0.26, p < 0.001), less instrumental support (OR 0.91, p < 0.001), and greater symptoms of anxiety (OR 1.1, p < 0.001). A new prescription of opioids six to nine months after injury was independently associated with less instrumental support (OR 0.9, p < 0.001) and greater symptoms of anxiety (OR 1.1, p < 0.001). Conclusion. This study demonstrates that potentially modifiable psychosocial factors are associated with increased acute and chronic opioid prescriptions following upper limb fracture. Surgeons prescribing opioids for upper limb fractures should be made aware of the screening and management of emotional and social health. Cite this article: Bone Jt Open 2021;2(2):119–124

Aims. Pain is the most frequent complaint associated with osteonecrosis of the femoral head (ONFH), but the factors contributing to such pain are poorly understood. This study explored diverse demographic, clinical, radiological, psychological, and neurophysiological factors for their potential contribution to pain in patients with ONFH. Methods. This cross-sectional study was carried out according to the “STrengthening the Reporting of OBservational studies in Epidemiology” statement. Data on 19 variables were collected at a single timepoint from 250 patients with ONFH who were treated at our medical centre between July and December 2023 using validated instruments or, in the case of hip pain, a numerical rating scale. Factors associated with pain severity were identified using hierarchical multifactor linear regression. Results. Regression identified the following characteristics as independently associated with higher pain score, after adjustment for potential confounders: Association Research Circulation Osseous classification stage IIIa or IIIb, bone marrow oedema, grade 3 joint effusion, as well as higher scores on pain catastrophizing, anxiety, and central sensitization. The final model explained 69.7% of observed variance in pain scores, of which clinical and radiological factors explained 37%, while psychological and neurophysiological factors explained 24% and demographic factors explained 8.7%. Conclusion. Multidimensional characteristics jointly contribute to the severity of pain associated with ONFH. These findings highlight the need to comprehensively identify potential contributors to pain, and to personalize management and treatment accordingly. Cite this article: Bone Joint Res 2024;13(11):673–681

Aims. The adequate provision of personal protective equipment (PPE) for healthcare workers has come under considerable scrutiny during the COVID-19 pandemic. This study aimed to evaluate staff awareness of PPE guidance, perceptions of PPE measures, and concerns regarding PPE use while caring for COVID-19 patients. In addition, responses of doctors, nurses, and other healthcare professionals (OHCPs) were compared. Methods. The inclusion criteria were all staff working in clinical areas of the hospital. Staff were invited to take part using a link to an online questionnaire advertised by email, posters displayed in clinical areas, and social media. Questions grouped into the three key themes - staff awareness, perceptions, and concerns - were answered using a five-point Likert scale. The Kruskal-Wallis test was used to compare results across all three groups of staff. Results. Overall, 315 staff took part in our study. There was a high awareness of PPE guidance at 84.4%, but only 52.4% of staff reported adequate PPE provision. 67.9% were still keen to come to work, despite very high levels of anxiety relating to contracting COVID-19 despite wearing PPE. Doctors had significantly higher ratings for questions relating to PPE awareness compared to other staff groups, while nursing staff and OHCPs had significantly higher levels of anxiety compared to doctors in relation to PPE and contracting COVID-19 (p < 0.05 using a Kruskal-Wallis test). Conclusion. We believe four recommendations are key to improve PPE measures and decrease anxiety: 1) nominated ward/department PPE champions; 2) anonymized reporting for PPE concerns; 3) formal PPE education sessions; and 4) drop-in counselling sessions for staff. We hope the insight and recommendations from this study can improve the PPE situation and maintain the health and wellbeing of the clinical work force, in order to care for COVID-19 patients safely and effectively

Aims. We performed a meta-analysis investigating the association between preoperative psychological distress and postoperative pain and function after total knee arthroplasty (TKA). Materials and Methods. Pubmed/Medline, Embase, PsycINFO, and the Cochrane library were searched for studies on the influence of preoperative psychological distress on postoperative pain and physical function after TKA. Two blinded reviewers screened for eligibility and assessed the risk of bias and the quality of evidence. We used random effects models to pool data for the meta-analysis. Results. Six prospective cohort studies, with a total of 1525 patients, were included. The random effects models showed significantly poorer outcomes in patients who preoperatively had elevated scores on the pain catastrophizing scale, worse 36-Item Short-Form Health Survey (SF-36) mental health score, symptoms of anxiety and/or depression, and somatization dysfunction. After 12 months, the standard mean difference for pain was −0.74 (95% confidence interval (CI) −1.04 to −0.44) and −0.56 (95% CI −0.80 to −0.32) for function. Conclusion. Preoperative pain catastrophizing, mental distress, symptoms of anxiety and/or depression, and somatoform disorders appear to adversely affect pain and function after TKA. Some patients undergoing TKA may therefore need psychological support to improve the outcome and quality of life

Aims. The aim of the study was to compare measures of the quality of life (QOL) after resection of a chordoma of the mobile spine with the national averages in the United States and to assess which factors influenced the QOL, symptoms of anxiety and depression, and coping with pain post-operatively in these patients. Patients and Methods. A total of 48 consecutive patients who underwent resection of a primary or recurrent chordoma of the mobile spine between 2000 and 2015 were included. A total of 34 patients completed a survey at least 12 months post-operatively. The primary outcome was the EuroQol-5 Dimensions (EQ-5D-3L) questionnaire. Secondary outcomes were the Patient-Reported Outcome Measurement Information System (PROMIS) anxiety, depression and pain interference questionnaires. Data which were recorded included the indication for surgery, the region of the tumour, the number of levels resected, the status of the surgical margins, re-operations, complications, neurological deficit, length of stay in hospital and rate of re-admission. Results. The median EQ-5D-3L score was 0.71 (interquartile range (IQR) 0.44 to 0.79) which is worse than the national average in the United States of 0.85 (p < 0.001). Anxiety (median: 55 (IQR 49 to 61), p = 0.031) and pain (median: 61 (IQR 56 to 68), p < 0.001) were also worse than the national average in the United States (50), while depression was not (median: 52 (IQR 38 to 57), p = 0.513). Patients who underwent a primary resection had better QOL and less anxiety, depression and pain compared with those who underwent resection for recurrent or residual disease. The one- and five-year probabilities were 0.96 and 0.74 for survival, 0.07 and 0.25 for tumour recurrence, and 0.02 and 0.16 for developing distant metastasis. A total of 25 local complications occurred in 20 patients (42%), and there were 50 systemic and other complications in 25 patients (52%) within 90 days. Conclusion. These patient reported outcomes and oncological and surgical outcomes can be used when counselling patients and to aid decision-making when planning surgery. Cite this article: Bone Joint J 2017;99-B:979–86

Aims. The primary aim of this study was to quantify the improvement in patient-reported outcome measures (PROMs) following total hip arthroplasty (THA), as well as the extent of any deterioration through the seven-year follow-up. The secondary aim was to identify predictors of PROM improvement and deterioration. Patients and Methods. A total of 976 patients were enrolled into a prospective, international, multicentre study. Patients completed a battery of PROMs prior to THA, at three months post-THA, and at one, three, five, and seven-years post-THA. The Harris Hip Score (HHS), the 36-Item Short-Form Health Survey (SF-36) Physical Component Summary (PCS), the SF-36 Mental Component Summary (MCS), and the EuroQol five-dimension three-level (EQ-5D) index were the primary outcomes. Longitudinal changes in each PROM were investigated by piece-wise linear mixed effects models. Clinically significant deterioration was defined for each patient as a decrease of one half of a standard deviation (group baseline). Results. Improvements were noted in each PROM between the preoperative and one-year visits, with one-year values exceeding age-matched population norms. Patients with difficulty in self-care experienced less improvement in HHS (odds ratio (OR) 2.2; p = 0.003). Those with anxiety/depression experienced less improvement in PCS (OR -3.3; p = 0.002) and EQ-5D (OR -0.07; p = 0.005). Between one and seven years, obesity was associated with deterioration in HHS (1.5 points/year; p = 0.006), PCS (0.8 points/year; p < 0.001), and EQ-5D (0.02 points/year; p < 0.001). Preoperative difficulty in self-care was associated with deterioration in HHS (2.2 points/year; p < 0.001). Preoperative pain from other joints was associated with deterioration in MCS (0.8 points/year; p < 0.001). All aforementioned factors were associated with clinically significant deterioration in PROMs (p < 0.035), except anxiety/depression with regard to PCS (p = 0.060). Conclusion. The present study finds that patient factors affect the improvement and deterioration in PROMs over the medium term following THA. Special attention should be given to patients with risk factors for decreased PROMs, both preoperatively and during follow-up. Cite this article: Bone Joint J 2019;101-B:768–778

Aims. Patient-reported outcome measures have become an important part of routine care. The aim of this study was to determine if Patient-Reported Outcomes Measurement Information System (PROMIS) measures can be used to create patient subgroups for individuals seeking orthopaedic care. Methods. This was a cross-sectional study of patients from Duke University Department of Orthopaedic Surgery clinics (14 ambulatory and four hospital-based). There were two separate cohorts recruited by convenience sampling (i.e. patients were included in the analysis only if they completed PROMIS measures during a new patient visit). Cohort #1 (n = 12,141; December 2017 to December 2018,) included PROMIS short forms for eight domains (Physical Function, Pain Interference, Pain Intensity, Depression, Anxiety, Sleep Quality, Participation in Social Roles, and Fatigue) and Cohort #2 (n = 4,638; January 2019 to August 2019) included PROMIS Computer Adaptive Testing instruments for four domains (Physical Function, Pain Interference, Depression, and Sleep Quality). Cluster analysis (K-means method) empirically derived subgroups and subgroup differences in clinical and sociodemographic factors were identified with one-way analysis of variance. Results. Cluster analysis yielded four subgroups with similar clinical characteristics in Cohort #1 and #2. The subgroups were: 1) Normal Function: within normal limits in Physical Function, Pain Interference, Depression, and Sleep Quality; 2) Mild Impairment: mild deficits in Physical Function, Pain Interference, and Sleep Quality but with Depression within normal limits; 3) Impaired Function, Not Distressed: moderate deficits in Physical Function and Pain Interference, but within normal limits for Depression and Sleep Quality; and 4) Impaired Function, Distressed: moderate (Physical Function, Pain Interference, and Sleep Quality) and mild (Depression) deficits. Conclusion. These findings suggest orthopaedic patient subgroups differing in physical function, pain, and psychosocial distress can be created from as few as four different PROMIS measures. Longitudinal research is necessary to determine whether these subgroups have prognostic validity. Cite this article: Bone Jt Open 2021;2(7):493–502

Objectives. To investigate psychosocial and biomedical outcomes following total hip replacement (THR) and to identify predictors of recovery from THR. Methods. Patients with osteoarthritis (OA) on the waiting list for primary THR in North West England were assessed pre-operatively and at six and 12 months post-operatively to investigate psychosocial and biomedical outcomes. Psychosocial outcomes were anxiety and depression, social support and health-related quality of life (HRQoL). Biomedical outcomes were pain, physical function and stiffness. The primary outcome was the Short-Form 36 (SF-36) Health Survey Total Physical Function. Potential predictors of outcome were age, sex, body mass index, previous joint replacement, involvement in the decision for THR, any comorbidities, any complications, type of medication, and pre-operative ENRICHD Social Support Instrument score, Hospital Anxiety and Depression scores and Western Ontario and McMaster Universities osteoarthritis index score. Results. The study included 206 patients undergoing THR. There were 88 men and 118 women with a mean age of 66.3 years (. sd. 10.4;36 to 89). Pain, stiffness and physical function, severity of OA, HRQoL, anxiety and depression all improved significantly from pre-operative to 12-month assessment (all p < 0.001), with the greatest improvement occurring in the first six months (all p < 0.001). The predictors that were found to influence recovery six months after THR were: pain (p < 0.001), anxiety (p = 0.034), depression (p = 0.001), previous joint replacement (p = 0.006) and anti-inflammatory drugs (p = 0.012). Conclusions. The study identified the key psychosocial and biomedical predictors of recovery following THR. By identifying these predictors, we are able to identify and provide more support for patients at risk of poor recovery following THR. Cite this article: Bone Joint Res 2013;2:248–54

In this study we hypothesised that anxiety/depression, one of five dimensions in the health-related quality of life (HRQoL) measurement tool EQ-5D, could predict outcome after total hip replacement surgery. Pre-operative and one-year post-operative data from the Swedish Hip Arthroplasty Register, including 6158 patients with primary osteoarthritis of the hip, were analysed. In order to examine the association between anxiety and outcome with respect to pain and satisfaction an analysis of covariance was used. The pre-operative EQ-5D anxiety/depression dimension was a strong predictor for pain relief and patient satisfaction (p < 0.001). Orthopaedic surgeons involved in the care of patients eligible for total hip replacement surgery should be aware that mental health may influence post-operative pain and HRQoL. An appropriate assessment of mental health may enable a modification in the way these patients are managed in order to optimise the outcome after joint replacement surgery

This cohort study investigated the influence of psychological factors, including perception of illness, anxiety and depression on recovery and functional outcome after total knee replacement surgery. . A total of 100 patients (55 male; 45 female) with a mean age of 71 (42 to 92) who underwent a primary total knee replacement for osteoarthritis were recruited into this study. In all 97 participants completed the six week and 87 the one year follow-up questionnaires. . Pre-operatively patients completed the revised Illness Perception Questionnaire, Hospital Anxiety and Depression Scale and Recovery Locus of Control Scale. Function was assessed pre-operatively, at six weeks and one year using Oxford Knee Score (OKS) and the goniometer-measured range of movement (ROM). . The results showed that pre-operative function had the biggest impact on post-operative outcome for ROM and OKS. In addition questionnaire variables and depression had an impact on the OKS at six weeks. Depression and anxiety were also associated with a higher (worse) knee score at one year but did not influence the ROM at either six weeks or one year. Recovery from total knee replacement can be difficult to predict. This study has identified psychological factors that play an important role in recovery from surgery and functional outcome. These should be taken into account when considering patients for total knee replacement. Cite this article: Bone Joint J 2014;96-B:210–16

Aims. A high rate of suicide has been reported in patients who sustain fractures, but the association remains uncertain in the context of other factors. The aim of this study was to examine the association between fractures and the risk of suicide in this contextual setting. Patients and Methods. We performed a case-control study of patients aged 40 years or older who died by suicide between 2000 and 2011. We included patients’ demographics, physical and mental health problems, and socioeconomic factors. We performed conditional logistic regression to evaluate the associations between fractures and the risk of suicide. Results. We included a total of 34 794 patients who died by suicide and 139 176 control patients. We found that fractures as a homogenous group (adjusted odds ratios (aOR), 1.48; 95% confidence interval (CI) 1.43 to 1.53), and specifically pelvic (aOR 2.04; 95% CI 1.68 to 2.47) and spinal fractures (aOR 1.53; 95% CI 1.43 to 1.64), were associated with a higher risk of suicide. In addition, we found that patients who had a lower income, had never married, had lower levels of educational attainment, or had coexistent physical and mental conditions such as anxiety, mood disorders, and psychosis-related disorders had a higher risk of suicide. Conclusion. Fractures, specifically those of the hip and spine, were associated with an increased risk of suicide. The findings suggest that greater clinical attention should be given to this risk in patients with fractures, especially for those with additional risk factors. Cite this article: Bone Joint J 2018;100-B:780–6

Aims. The primary aim of this study was to determine the surgical team’s learning curve for introducing robotic-arm assisted unicompartmental knee arthroplasty (UKA) into routine surgical practice. The secondary objective was to compare accuracy of implant positioning in conventional jig-based UKA versus robotic-arm assisted UKA. Patients and Methods. This prospective single-surgeon cohort study included 60 consecutive conventional jig-based UKAs compared with 60 consecutive robotic-arm assisted UKAs for medial compartment knee osteoarthritis. Patients undergoing conventional UKA and robotic-arm assisted UKA were well-matched for baseline characteristics including a mean age of 65.5 years (. sd. 6.8) vs 64.1 years (. sd. 8.7), (p = 0.31); a mean body mass index of 27.2 kg.m2 (. sd. 2.7) vs 28.1 kg.m2 (. sd. 4.5), (p = 0.25); and gender (27 males: 33 females vs 26 males: 34 females, p = 0.85). Surrogate measures of the learning curve were prospectively collected. These included operative times, the Spielberger State-Trait Anxiety Inventory (STAI) questionnaire to assess preoperative stress levels amongst the surgical team, accuracy of implant positioning, limb alignment, and postoperative complications. Results. Robotic-arm assisted UKA was associated with a learning curve of six cases for operating time (p < 0.001) and surgical team confidence levels (p < 0.001). Cumulative robotic experience did not affect accuracy of implant positioning (p = 0.52), posterior condylar offset ratio (p = 0.71), posterior tibial slope (p = 0.68), native joint line preservation (p = 0.55), and postoperative limb alignment (p = 0.65). Robotic-arm assisted UKA improved accuracy of femoral (p < 0.001) and tibial (p < 0.001) implant positioning with no additional risk of postoperative complications compared to conventional jig-based UKA. Conclusion. Robotic-arm assisted UKA was associated with a learning curve of six cases for operating time and surgical team confidence levels but no learning curve for accuracy of implant positioning. Cite this article: Bone Joint J 2018;100-B:1033–42

Aims. The purpose of this study was to evaluate trends in opioid use after unicompartmental knee arthroplasty (UKA), to identify predictors of prolonged use and to compare the rates of opioid use after UKA, total knee arthroplasty (TKA) and total hip arthroplasty (THA). Materials and Methods. We identified 4205 patients who had undergone UKA between 2007 and 2015 from the Humana Inc. administrative claims database. Post-operative opioid use for one year post-operatively was assessed using the rates of monthly repeat prescription. These were then compared between patients with and without a specific variable of interest and with those of patients who had undergone TKA and THA. Results. A total of 4205 UKA patients were analysed. Of these, 1362 patients (32.4%) were users of opioids. Pre-operative opioid use was the strongest predictor of prolonged opioid use after UKA. Opioid users were 1.4 (81.6% versus 57.7%), 3.7 (49.5% versus 13.3%) and 5.5 (35.8% versus 6.5%) times more likely to be taking opioids at one, two and three months post-operatively, respectively (p < 0.05 for all). Younger age and specific comorbidities such as anxiety/depression, smoking, back pain and substance abuse were found to significantly increase the rate of repeat prescription for opioids after UKA. Overall, UKA patients required significantly less opioid prescriptions than patients who had undergone THA and TKA. Conclusion. One-third of patients who undergo UKA are given opioids in the three months pre-operatively. Pre-operative opioid use is the best predictor of increased repeat prescriptions after UKA. However, other intrinsic patient characteristics are also predictive. Cite this article: Bone Joint J 2018;100-B(1 Supple A):62–7

Objectives. This study reports on a secondary exploratory analysis of the early clinical outcomes of a randomised clinical trial comparing robotic arm-assisted unicompartmental knee arthroplasty (UKA) for medial compartment osteoarthritis of the knee with manual UKA performed using traditional surgical jigs. This follows reporting of the primary outcomes of implant accuracy and gait analysis that showed significant advantages in the robotic arm-assisted group. Methods. A total of 139 patients were recruited from a single centre. Patients were randomised to receive either a manual UKA implanted with the aid of traditional surgical jigs, or a UKA implanted with the aid of a tactile guided robotic arm-assisted system. Outcome measures included the American Knee Society Score (AKSS), Oxford Knee Score (OKS), Forgotten Joint Score, Hospital Anxiety Depression Scale, University of California at Los Angeles (UCLA) activity scale, Short Form-12, Pain Catastrophising Scale, somatic disease (Primary Care Evaluation of Mental Disorders Score), Pain visual analogue scale, analgesic use, patient satisfaction, complications relating to surgery, 90-day pain diaries and the requirement for revision surgery. Results. From the first post-operative day through to week 8 post-operatively, the median pain scores for the robotic arm-assisted group were 55.4% lower than those observed in the manual surgery group (p = 0.040). At three months post-operatively, the robotic arm-assisted group had better AKSS (robotic median 164, interquartile range (IQR) 131 to 178, manual median 143, IQR 132 to 166), although no difference was noted with the OKS. At one year post-operatively, the observed differences with the AKSS had narrowed from a median of 21 points to a median of seven points (p = 0.106) (robotic median 171, IQR 153 to 179; manual median 164, IQR 144 to 182). No difference was observed with the OKS, and almost half of each group reached the ceiling limit of the score (OKS > 43). A greater proportion of patients receiving robotic arm-assisted surgery improved their UCLA activity score. Binary logistic regression modelling for dichotomised outcome scores predicted the key factors associated with achieving excellent outcome on the AKSS: a pre-operative activity level > 5 on the UCLA activity score and use of robotic-arm surgery. For the same regression modelling, factors associated with a poor outcome were manual surgery and pre-operative depression. Conclusion. Robotic arm-assisted surgery results in improved early pain scores and early function scores in some patient-reported outcomes measures, but no difference was observed at one year post-operatively. Although improved results favoured the robotic arm-assisted group in active patients (i.e. UCLA ⩾ 5), these do not withstand adjustment for multiple comparisons. Cite this article: M. J. G. Blyth, I. Anthony, P. Rowe, M. S. Banger, A. MacLean, B. Jones. Robotic arm-assisted versus conventional unicompartmental knee arthroplasty: Exploratory secondary analysis of a randomised controlled trial. Bone Joint Res 2017;6:631–639. DOI: 10.1302/2046-3758.611.BJR-2017-0060.R1

We identified a group of patients from the Swedish Arthroplasty Register who reported no relief of pain or worse pain one year after a total knee replacement (TKR). A total of two different patient-reported pain scores were used during this process. We then evaluated how the instruments used to measure pain affected the number of patients who reported no relief of pain or worse pain, and the relative effect of potential risk factors. . Between 2008 and 2010, 2883 TKRs were performed for osteoarthritis in two Swedish arthroplasty units. After applying exclusion criteria, 2123 primary TKRs (2123 patients) were included in the study. The Knee injury and Osteoarthritis Outcome Score (KOOS) and a Visual Analogue Scale (VAS) for knee pain were used to assess patients pre-operatively and one year post-operatively. . Only 50 of the 220 patients (23%) who reported no pain relief on either the KOOS pain subscale or the VAS for knee pain did so with both of these instruments. Patients who reported no pain relief on either measure tended to have less pain pre-operatively but a higher degree of anxiety. Charnley category C was a predictor for not gaining pain relief as measured on a VAS for knee pain. . The number of patients who are not relieved of pain after a TKR differs considerably depending on the instrument used to measure pain. . Cite this article: Bone Joint J 2014;96-B:1222–6

Aims

To map literature on prognostic factors related to outcomes of revision total knee arthroplasty (rTKA), to identify extensively studied factors and to guide future research into what domains need further exploration.

The October 2024 Children’s orthopaedics Roundup³⁶⁰ looks at: Cost-effectiveness analysis of soft bandage and immediate discharge versus rigid immobilization in children with distal radius torus fractures: the FORCE trial; Percutaneous Achilles tendon tenotomy in clubfoot with a blade or a needle: a single-centre randomized controlled noninferiority trial; Treatment of hip displacement in children with cerebral palsy: a five-year comparison of proximal femoral osteotomy and combined femoral-pelvic osteotomy in 163 children; The Core outcome Clubfoot (CoCo) study: relapse, with poorer clinical and quality of life outcomes, affects 37% of idiopathic clubfoot patients; Retention versus removal of epiphyseal screws in paediatric distal tibial fractures: no significant impact on outcomes; Predicting the resolution of residual acetabular dysplasia after brace treatment in infant DDH; Low prevalence of acetabular dysplasia following treatment for neonatal hip instability: a long-term study; How best to distract the patient?.