Aims. The aim of this study was to perform the first population-based description of the epidemiological and health economic burden of fracture-related infection (FRI). Methods. This is a retrospective cohort study of operatively managed orthopaedic trauma patients from 1 January 2007 to 31 December 2016, performed in Queensland, Australia. Record linkage was used to develop a person-centric, population-based dataset incorporating routinely collected administrative, clinical, and health economic information. The FRI group consisted of patients with International Classification of Disease 10th Revision diagnosis codes for deep infection associated with an implanted device within two years following surgery, while all others were deemed not infected. Demographic and clinical variables, as well as healthcare utilization costs, were compared. Results. There were 111,402 patients operatively managed for orthopaedic trauma, with 2,775 of these (2.5%) complicated by FRI. The development of FRI had a statistically significant association with older age, male sex, residing in rural/remote areas, Aboriginal or Torres Strait Islander background, lower socioeconomic status, road traffic accident, work-related injuries, open fractures, anatomical region (lower limb, spine, pelvis), high injury severity, requiring soft-tissue coverage, and medical comorbidities (univariate analysis). Patients with FRI had an eight-times longer median inpatient length of stay (24 days vs 3 days), and a 2.8-times higher mean estimated inpatient hospitalization cost (AU$56,565 vs AU$19,773) compared with uninfected patients. The total estimated inpatient cost of the FRI cohort to the healthcare system was AU$156.9 million over the ten-year period. Conclusion. The results of this study advocate for improvements in trauma care and infection management, address social determinants of health, and highlight the upside potential to improve prevention and treatment strategies. Cite this article: Bone Joint J 2024;106-B(1):77–85

Aims. Dislocation is a major concern following total hip arthroplasty (THA) for osteoarthritis (OA). Both dual-mobility components and standard acetabular components with large femoral heads are used to reduce the risk of dislocation. We investigated whether dual-mobility components are superior to standard components in reducing the two-year dislocation and revision risk in a propensity-matched sample from the Danish Hip Arthroplasty Register (DHR). Methods. This population-based cohort study analyzed data from the DHR and the Danish National Patient Register. We included all patients undergoing primary THA for OA from January 2010 to December 2019 with either dual-mobility or standard acetabular components with metal-on-polyethylene or ceramic-on-polyethylene articulations with a 36 mm femoral head. The samples were propensity score-matched on patient and implant characteristics. The primary outcome was the difference in the absolute risk of dislocation within two years, with a secondary outcome of the difference in the absolute risk of revision surgery of any cause within the same timeframe. The cumulative incidence of dislocation was calculated using the Aalen-Johansen estimator, while the difference in absolute risk was estimated using absolute risk regression (ARR). Results. We included 4,499 patients with dual-mobility components and 4,499 patients with standard components after propensity score-matching. Both groups had a mean age of 75 years (SD 8.5), included approximately 60% females, and had a two-year survival of 95.3% (95% CI 94.6 to 95.9). The dual-mobility group was 80% less likely to dislocate within two years (ARR 0.20 (95% CI 0.14 to 0.28); p < 0.001), with no significant difference in the risk of revision compared to standard components (ARR 1.15 (95% CI 0.89 to 1.48); p = 0.293). Conclusion. Dual-mobility components are associated with a reduced risk of dislocation and with no significant difference in the risk of revision for any cause within two years of THA when compared to standard acetabular components with 36 mm femoral heads. Cite this article: Bone Joint J 2025;107-B(1):50–57

Modern healthcare contracting is shifting the responsibility for improving quality, enhancing community health and controlling the total cost of care for patient populations from payers to providers. Population-based contracting involves capitated risk taken across an entire population, such that any included services within the contract are paid for by the risk-bearing entity throughout the term of the agreement. Under such contracts, a risk-bearing entity, which may be a provider group, a hospital or another payer, administers the contract and assumes risk for contractually defined services. These contracts can be structured in various ways, from professional fee capitation to full global per member per month diagnosis-based risk. The entity contracting with the payer must have downstream network contracts to provide the care and facilities that it has agreed to provide. Population health is a very powerful model to reduce waste and costs. It requires a deep understanding of the nuances of such contracting and the appropriate infrastructure to manage both networks and risk. Cite this article: Bone Joint J 2017;99-B:1431–4

Aims. Few risk factors for rotator cuff disease (RCD) and corresponding treatment have been firmly established. The aim of this study was to evaluate the relationship between numerous risk factors and the incidence of surgery for RCD in a large cohort. Methods. A population-based cohort of people aged between 40 and 69 years in the UK (the UK Biobank) was studied. People who underwent surgery for RCD were identified through a link with NHS inpatient records covering a mean of eight years after enrolment. Multivariate Cox proportional hazards regression was used to calculate hazard ratios (HRs) as estimates of associations with surgery for RCD accounting for confounders. The risk factors which were considered included age, sex, race, education, Townsend deprivation index, body mass index (BMI), occupational demands, and exposure to smoking. Results. Of the 421,894 people who were included, 47% were male. The mean age at the time of enrolment was 56 years (40 to 69). A total of 2,156 people were identified who underwent surgery for RCD. Each decade increase in age was associated with a 55% increase in the incidence of RCD surgery (95% confidence interval (CI) 46% to 64%). Male sex, non-white race, lower deprivation score, and higher BMI were significantly associated with a higher risk of surgery for RCD (all p < 0.050). Greater occupational physical demands were significantly associated with higher rates of RCD surgery (HR = 2.1, 1.8, and 1.4 for ‘always’, ‘usually’, and ‘sometimes’ doing heavy manual labour vs ‘never’, all p < 0.001). Former smokers had significantly higher rates of RCD surgery than those who had never smoked (HR 1.23 (95% CI 1.12 to 1.35), p < 0.001), while current smokers had similar rates to those who had never smoked (HR 0.94 (95% CI 0.80 to 1.11)). Among those who had never smoked, the risk of surgery was higher among those with more than one household member who smoked (HR 1.78 (95% CI 1.08 to 2.92)). The risk of RCD surgery was not significantly related to other measurements of secondhand smoking. Conclusion. Many factors were independently associated with surgery for RCD, including older age, male sex, higher BMI, lower deprivation score, and higher occupational physical demands. Several of the risk factors which were identified are modifiable, suggesting that the healthcare burden of RCD might be reduced through the pursuit of public health goals, such as reducing obesity and modifying occupational demands. Cite this article: Bone Joint J 2020;102-B(3):352–359

Aims. Few studies have compared survivorship of total shoulder arthroplasty (TSA) with hemiarthroplasty (HA). This observational study compared survivorship of TSA with HA while controlling for important covariables and accounting for death as a competing risk. Patients and Methods. All patients who underwent shoulder arthroplasty in Ontario, Canada between April 2002 and March 2012 were identified using population-based health administrative data. We used the Fine–Gray sub-distribution hazard model to measure the association of arthroplasty type with time to revision surgery (accounting for death as a competing risk) controlling for age, gender, Charlson Comorbidity Index, income quintile, diagnosis, and surgeon factors. Results. During the study period, 5777 patients underwent shoulder arthroplasty (4079 TSA, 70.6%; 1698 HA, 29.4%), 321 (5.6%) underwent revision, and 1090 (18.9%) died. TSA patients were older (TSA mean age 68.4 years (. sd. 10.2) vs HA mean age 66.5 years (. sd. 12.7); p = 0.001). The proportion of female patients was slightly lower in the TSA group (58.0% vs 58.4%). The adjusted association between surgery type and time to shoulder revision interacted significantly with patient age. Compared with TSA patients, revision was more common in the HA group (adjusted-health ratio (HR) 1.214, 95% confidence interval (CI) 0.96 to 1.53) but this did not reach statistical significance. Conclusion. Although there was a trend towards higher revision risk in patients undergoing HA, we found no statistically significant difference in survivorship between patients undergoing TSA or HA. Cite this article: Bone Joint J 2019;101-B:454–460

We reviewed 129 patients with subcutaneous sarcoma diagnosed from 1964 to the end of 1985 in a population-based series of sarcoma cases from southern Sweden. The annual incidence was 0.4 per 100,000, comprising 32% of all soft-tissue sarcomas of the extremities or the trunk wall. Compared to deep-seated sarcomas, subcutaneous tumours were half the size at diagnosis, more common in the lower leg and foot, more often malignant fibrous histiocytoma, and of a lower grade of malignancy. None of the low-grade and only 7% of the high-grade tumours recurred locally after wide local excision without radiotherapy. The cumulative five-year survival for all 129 patients was 80%. Multivariate analysis identified only high grade of malignancy and the size of the tumour (greater than 5 cm) as independent prognostic factors. We conclude that systemic or local adjuvant therapy is not generally indicated for subcutaneous sarcoma because of the good prognosis and low local recurrence rate after wide excision

The management of spinal metastases is palliative and aimed at improving quality of life at an acceptable risk. This population study uses administrative databases and measures survivorship and complication rates after surgery for spinal metastases. The effects of various potential predictor variables were evaluated. We identified 987 patients with a median survival for all types of cancer of 227 days. The one and three-month mortality was 9% and 29%, respectively. Increasing age, male gender and primary lung cancer were significant risk factors for death within 30 days of surgery. A preoperative neurological deficit contributed a 19% increase in mortality and a 71% increase in the risk of postoperative wound infection. We found an overall major complication rate of 27%. This information will provide patients, families and clinicians with objective data which will help in the choice of treatment and the understanding of the surgical risk and outcome.

In Norway total joint replacement after hip dysplasia is reported more commonly than in neighbouring countries, implying a higher prevalence of the condition. We report on the prevalence of radiological features associated with hip dysplasia in a population of 2081 19-year-old Norwegians. The radiological measurements used to define hip dysplasia were Wiberg’s centre-edge (CE) angle at thresholds of < 20° and < 25°, femoral head extrusion index <  75%, Sharp’s angle > 45°, an acetabular depth to width ratio < 250 and the sourcil shape assessed subjectively. The whole cohort underwent clinical examination of their range of hip movement, body mass index (BMI), and Beighton hypermobility score, and were asked to complete the EuroQol (EQ-5D) and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC). The prevalence of hip dysplasia in the cohort varied from 1.7% to 20% depending on the radiological marker used. A Wiberg’s CE angle <  20° was seen in 3.3% of the cohort: 4.3% in women and 2.4% in men. We found no association between subjects with multiple radiological signs indicative of dysplasia and BMI, Beighton score, EQ-5D or WOMAC. Although there appears to be a high prevalence of hip dysplasia among 19-year-old Norwegians, this is dependent on the radiological parameters applied.

Cite this article: Bone Joint J 2013;95-B:279–85.

Aims. Developmental cervical spinal stenosis (DcSS) is a well-known predisposing factor for degenerative cervical myelopathy (DCM) but there is a lack of consensus on its definition. This study aims to define DcSS based on MRI, and its multilevel characteristics, to assess the prevalence of DcSS in the general population, and to evaluate the presence of DcSS in the prediction of developing DCM. Methods. This cross-sectional study analyzed MRI spine morphological parameters at C3 to C7 (including anteroposterior (AP) diameter of spinal canal, spinal cord, and vertebral body) from DCM patients (n = 95) and individuals recruited from the general population (n = 2,019). Level-specific median AP spinal canal diameter from DCM patients was used to screen for stenotic levels in the population-based cohort. An individual with multilevel (≥ 3 vertebral levels) AP canal diameter smaller than the DCM median values was considered as having DcSS. The most optimal cut-off canal diameter per level for DcSS was determined by receiver operating characteristic analyses, and multivariable logistic regression was performed for the prediction of developing DCM that required surgery. Results. A total of 2,114 individuals aged 64.6 years (SD 11.9) who underwent surgery from March 2009 to December 2016 were studied. The most optimal cut-off canal diameters for DcSS are: C3 < 12.9 mm, C4 < 11.8 mm, C5 < 11.9 mm, C6 < 12.3 mm, and C7 < 13.3 mm. Overall, 13.0% (262 of 2,019) of the population-based cohort had multilevel DcSS. Multilevel DcSS (odds ratio (OR) 6.12 (95% CI 3.97 to 9.42); p < 0.001) and male sex (OR 4.06 (95% CI 2.55 to 6.45); p < 0.001) were predictors of developing DCM. Conclusion. This is the first MRI-based study for defining DcSS with multilevel canal narrowing. Level-specific cut-off canal diameters for DcSS can be used for early identification of individuals at risk of developing DCM. Individuals with DcSS at ≥ three levels and male sex are recommended for close monitoring or early intervention to avoid traumatic spinal cord injuries from stenosis. Cite this article: Bone Joint J 2024;106-B(11):1333–1341

Aims. This study aims to determine difference in annual rate of early-onset (≤ 90 days) deep surgical site infection (SSI) following primary total knee arthroplasty (TKA) for osteoarthritis, and to identify risk factors that may be associated with infection. Methods. This is a retrospective population-based cohort study using prospectively collected patient-level data between 1 January 2013 and 1 March 2020. The diagnosis of deep SSI was defined as per the Centers for Disease Control/National Healthcare Safety Network criteria. The Mann-Kendall Trend test was used to detect monotonic trends in annual rates of early-onset deep SSI over time. Multiple logistic regression was used to analyze the effect of different patient, surgical, and healthcare setting factors on the risk of developing a deep SSI within 90 days from surgery for patients with complete data. We also report 90-day mortality. Results. A total of 39,038 patients underwent primary TKA for osteoarthritis during the study period. Of these, 275 patients developed a deep SSI within 90 days of surgery, representing a cumulative incidence of 0.7%. The annual infection rate did not significantly decrease over the seven-year study period (p = 0.162). Overall, 13,885 (35.5%) cases were excluded from the risk analysis due to missing data. Risk factors associated with early-onset deep SSI included male sex, American Society of Anesthesiologists grade ≥ 3, blood transfusion, acute length of stay, and surgeon volume < 30 TKAs/year. Early-onset deep SSI was not associated with increased 90-day mortality. Conclusion. This study establishes a reliable baseline infection rate for early-onset deep SSI after TKA for osteoarthritis using robust Infection Prevention and Control surveillance data, and identifies several potentially modifiable risk factors. Cite this article: Bone Joint J 2023;105-B(9):971–976

Aims. Pneumatic tourniquets are often used during the surgical treatment of unstable traumatic ankle fractures. The aim of this study was to assess the risk of reoperation after open reduction and internal fixation of ankle fractures with and without the use of pneumatic tourniquets. Methods. This was a population-based cohort study using data from the Danish Fracture Database with a follow-up period of 24 months. Data were linked to the Danish National Patient Registry to ensure complete information regarding reoperations due to complications, which were divided into major and minor. The relative risk of reoperations for the tourniquet group compared with the non-tourniquet group was estimated using Cox proportional hazards modelling. Results. A total of 4,050 ankle fractures treated with open reduction and internal fixation between 15 March 2012 and 31 December 2016 were included, with 669 (16.5%) undergoing surgery with a tourniquet and 3,381 (83.5%) without a tourniquet. The overall reoperation risk was 28.2% with an adjusted relative risk of 1.46 (95% CI 0.91 to 2.32) for group comparison. The reoperation risk due to major complications was 3.1% with a tourniquet and 4.4% without a tourniquet, resulting in an adjusted relative risk of 1.45 (95% CI 0.91 to 2.32). For minor complications, there were 24.7% and 23.9% reoperations, resulting in an adjusted relative risk of 0.99 (95% CI 0.84 to 1.17). Conclusion. We found no significant difference in the reoperation rate when comparing ankle fractures treated surgically with and without the use of pneumatic tourniquets. Cite this article: Bone Joint J 2024;106-B(9):994–999

Aims. This study aimed to describe practice variation in the use of total hip arthroplasty (THA) for older patients with femoral neck fracture and to determine the association between patient, surgeon, and institution factors and treatment with THA. Methods. We performed a cross-sectional analysis of 49,597 patients aged 60 years and older from Ontario, Canada, who underwent hemiarthroplasty or THA for femoral neck fracture between 2002 and 2017. This population-based study used routinely collected healthcare databases linked through ICES (formerly known as the Institute for Clinical Evaluative Sciences). Multilevel logistic regression modelling was used to quantify the association between patient, surgeon, and institution-level variables and whether patients were treated with THA. Variance partition coefficient and median odds ratios were used to estimate the variation attributable to higher-level variables and the magnitude of effect of higher-level variables, respectively. Results. Over the study period, 9.4% of patients (n = 4,638) were treated with THA. Patient factors associated with higher likelihood of treatment by THA included: younger age, male sex, and diagnosis with rheumatoid arthritis. Long-term care residence, use of home care services prior to hip fracture, diagnosis of dementia, higher comorbidity burden, and the most marginalized group were negatively associated with treatment by THA. Treating surgeon and institution accounted for 54.2% and 17.8% of the total variation in treatment with THA, respectively. Surgeon volume of THA procedures in the 365 days prior to surgery was the strongest higher-level predictor of treatment with THA. Specific treating surgeons and institutions still accounted for significant proportions of the variability in treatment with THA (40.3% and 19.5% of total observed variation, respectively) after controlling for available patient, surgeon, and institution-level variables. Conclusion. The strongest predictors for treatment of patients with femoral neck fracture with THA were patient age, treating surgeon, and treating institution. This practice variation highlights differential access to care for patients. Cite this article: Bone Joint J 2023;105-B(2):180–189

Aims. We first sought to compare survival for patients treated surgically for solitary and multiple metastases in the appendicular skeleton, and second, to explore the role of complete and incomplete resection (R0 and R1/R2) in patients with a solitary bony metastasis in the appendicular skeleton. Methods. We conducted a retrospective study on a population-based cohort of all adult patients treated surgically for bony metastases of the appendicular skeleton between January 2014 and December 2019. We excluded patients in whom the status of bone metastases and resection margin was unknown. Patients were followed until the end of the study or to their death. We had no loss to follow-up. We used Kaplan-Meier analysis (with log-rank test) to evaluate patient survival. We identified 506 operations in 459 patients. A total of 120 operations (in 116 patients) were for solitary metastases and 386 (in 345 patients) for multiple metastases. Of the 120 operations, 70 (in 69 patients) had no/an unknown status of visceral metastases (solitary group) and 50 (in 49 patients) had visceral metastases. In the solitary group, 45 operations (in 44 patients) were R0 (resections for cure or complete remission) and 25 (in 25 patients) were R1/R2 (resections leaving microscopic or macroscopic tumour, respectively). The most common types of cancer in the solitary group were kidney (n = 27), lung (n = 25), and breast (n = 20). Results. The one-year patient survival was 47% (95% confidence interval (CI) 38 to 57) for the solitary bony metastases and 34% (95% CI 29 to 39) for multiple bone metastases (p < 0.001). The one-year patient survival was 64% (95% CI 52 to 75) for solitary bony metastases without/with unknown visceral metastases and 23% (95% CI 11 to 36) for solitary bony metastases with visceral metastases (p < 0.001). The one-year patient survival was 75% (95% CI 62 to 89) for a solitary bony metastasis after R0 surgery and 42% (95% CI 22 to 61) for a solitary bony metastasis with R1/R2 surgery (p < 0.001). Conclusion. Our study suggests that the surgical treatment of patients with a solitary bony metastasis to the appendicular skeleton results in better survival than for patients with multiple bony metastases. Furthermore, aggressive treatment of a solitary bony metastasis with R0 surgery may improve patient survival. Cite this article: Bone Joint J 2023;105-B(11):1206–1215

Aims. We evaluated the national and regional trends from 2013 to 2022, in the prevalence of Perthes’ disease among adolescent males in South Korea. Methods. This retrospective, nationwide, population-based study included a total of 3,166,669 Korean adolescent males examined at regional Military Manpower Administration (MMA) offices over ten years. Data from the MMA were retrospectively collected to measure the national and regional prevalence per 100,000 and 95% CI of Perthes’ disease according to the year (1 January 2013 to 31 December 2022) and history of pelvic and/or femoral osteotomy in South Korea. Spearman’s correlation analysis was performed to assess the relationship between the Perthes’ disease prevalence and several related factors. Results. The prevalence of Perthes’ disease showed a gradually increasing trend for a ten-year follow-up period from 2013 to 2022 with a mean of 71.17 (95% CI 61.82 to 80.52) per 100,000, ranging from 56.02 (95% CI 48.34 to 63.71) in 2013 to 77.53 (95% CI 67.94 to 87.11) in 2019. The proportion of patients with a Stulberg classification ≥ III ranged from 50.57% in 2015 to 80.08% in 2019, showing a gradually increasing trend. Following the trend for Perthes’ disease, an increase in the proportion of pelvic and/or femoral osteotomies was observed, whereas conservative treatment decreased in adolescent males. For a ten-year follow-up period, the prevalence of Perthes’ disease was highest in provinces, followed by the metropolitan area and Seoul. Conclusion. The prevalence of Perthes’ disease in adolescent males increased over time from 2013 to 2022. In particular, the trend in the prevalence of Perthes’ disease with incongruent hips was significantly associated with overweight and obesity rates among male adolescents with a very high level of correlation. Cite this article: Bone Joint J 2025;107-B(1):42–49

Aims. Repeated lumbar spine surgery has been associated with inferior clinical outcomes. This study aimed to examine and quantify the impact of this association in a national clinical register cohort. Methods. This is a population-based study from the Norwegian Registry for Spine surgery (NORspine). We included 26,723 consecutive cases operated for lumbar spinal stenosis or lumbar disc herniation from January 2007 to December 2018. The primary outcome was the Oswestry Disability Index (ODI), presented as the proportions reaching a patient-acceptable symptom state (PASS; defined as an ODI raw score ≤ 22) and ODI raw and change scores at 12-month follow-up. Secondary outcomes were the Global Perceived Effect scale, the numerical rating scale for pain, the EuroQoL five-dimensions health questionnaire, occurrence of perioperative complications and wound infections, and working capability. Binary logistic regression analysis was conducted to examine how the number of previous operations influenced the odds of not reaching a PASS. Results. The proportion reaching a PASS decreased from 66.0% (95% confidence interval (CI) 65.4 to 66.7) in cases with no previous operation to 22.0% (95% CI 15.2 to 30.3) in cases with four or more previous operations (p < 0.001). The odds of not reaching a PASS were 2.1 (95% CI 1.9 to 2.2) in cases with one previous operation, 2.6 (95% CI 2.3 to 3.0) in cases with two, 4.4 (95% CI 3.4 to 5.5) in cases with three, and 6.9 (95% CI 4.5 to 10.5) in cases with four or more previous operations. The ODI raw and change scores and the secondary outcomes showed similar trends. Conclusion. We found a dose-response relationship between increasing number of previous operations and inferior outcomes among patients operated for degenerative conditions in the lumbar spine. This information should be considered in the shared decision-making process prior to elective spine surgery. Cite this article: Bone Joint J 2023;105-B(4):422–430

Aims. The aim of this study was to assess the association of mortality and reoperation when comparing cemented and uncemented hemiarthroplasty (HA) in hip fracture patients aged over 65 years. Methods. This was a population-based cohort study on hip fracture patients using prospectively gathered data from several national registries in Denmark from 2004 to 2015 with up to five years follow-up. The primary outcome was mortality and the secondary outcome was reoperation. Hazard ratios (HRs) for mortality and subdistributional hazard ratios (sHRs) for reoperations are shown with 95% confidence intervals (CIs). Results. A total of 17,671 patients with primary HA were identified (9,484 uncemented and 8,187 cemented HAs). Compared to uncemented HA, surgery with cemented HA was associated with an absolute risk difference of 0.4% for mortality within the period zero to one day after surgery and an adjusted HR of 1.70 (95% CI 1.22 to 2.38). After seven days, there was no longer any association, with an adjusted HR of 1.07 (95% CI 0.90 to 1.28). This continued until five years after surgery with a HR of 1.01 (95% CI 0.96 to 1.06). There was a higher proportion of reoperations due to any reason after five years in the uncemented group with 10.2% compared to the cemented group with 6.1%. This yielded an adjusted sHR of 0.65 (95% CI 0.57 to 0.75) and difference continued up until five years after the surgery, demonstrating a sHR of 0.70 (95% CI 0.59 to 0.83). Conclusion. In a non-selected cohort of hip fracture patients, surgery with cemented HA was associated with a higher relative mortality during the first postoperative day compared to surgery with uncemented HA, but there was no difference after seven days up until five years after. In contrast, surgery with cemented HA was associated with lower risk of reoperation up to five years postoperatively compared with surgery with uncemented HA. There was a higher relative mortality on the first postoperative day for cemented HA versus uncemented HA. There was no difference in mortality after seven days up until five years after surgery. There were 6.1% reoperations for cemented HA compared to 10.2% for uncemented HA after five years. Cite this article: Bone Joint J 2022;104-B(1):127–133

Aims. Total hip arthroplasty (THA) is one of the most successful surgical procedures. The objectives of this study were to define whether there is a correlation between socioeconomic status (SES) and surgical complications after elective primary unilateral THA, and investigate whether access to elective THA differs within SES groups. Methods. We conducted a retrospective, population-based cohort study involving 202 hospitals in Ontario, Canada, over a 17-year period. Patients were divided into income quintiles based on postal codes as a proxy for personal economic status. Multivariable logistic regression models were then used to primarily assess the relationship between SES and surgical complications within one year of index THA. Results. Of 111,359 patients who underwent elective primary THA, those in the lower SES groups had statistically significantly more comorbidities and statistically significantly more postoperative complications. While there was no increase in readmission rates within 90 days, there was a statistically significant difference in the primary and secondary outcomes including all revisions due (with a subset of deep wound infection and dislocation). Results showed that those in the higher SES groups had proportionally more cases performed than those in lower groups. Compared to the highest SES quintile, the lower groups had 61% of the number of hip arthroplasties performed. Conclusion. Patients in lower socioeconomic groups have more comorbidities, fewer absolute number of cases performed, have their procedures performed in lower-volume centres, and ultimately have higher rates of complications. This lack of access and higher rates of complications is a “double hit” to those in lower SES groups, and indicates that we should be concentrating efforts to improve access to surgeons and hospitals where arthroplasty is routinely performed in high numbers. Even in a universal healthcare system where there are no penalties for complications such as readmission, there seems to be an inequality in the access to THA. Cite this article: Bone Joint J 2022;104-B(5):589–597

Aims. The Uppföljningsprogram för cerebral pares (CPUP) Hip Score distinguishes between children with cerebral palsy (CP) at different levels of risk for displacement of the hip. The score was constructed using data from Swedish children with CP, but has not been confirmed in any other population. The aim of this study was to determine the calibration and discriminatory accuracy of this score in children with CP in Scotland. Methods. This was a total population-based study of children registered with the Cerebral Palsy Integrated Pathway Scotland. Displacement of the hip was defined as a migration percentage (MP) of > 40%. Inclusion criteria were children in Gross Motor Function Classification System (GMFCS) levels III to V. The calibration slope was estimated and Kaplan-Meier curves produced for five strata of CPUP scores to compare the observed with the predicted risk of displacement of the hip at five years. For discriminatory accuracy, the time-dependent area under the receiver operating characteristic curve (AUC) was estimated. In order to analyze differences in the performance of the score between cohorts, score weights, and subsequently the AUC, were re-estimated using the variables of the original score: the child’s age at the first examination, GMFCS level, head shaft angle, and MP of the worst hip in a logistic regression with imputation of outcomes for those with incomplete follow-up. Results. The discriminatory accuracy of the score in the new population of 367 children was high (AUC 0.78 (95% confidence interval (CI) 0.71 to 0.86)). The calibration of the score was insufficient (slope 0.48 (95% CI 0.31 to 0.65)), and the absolute risks of displacement of the hip in this population were overestimated. The AUC increased with re-estimated weights (0.85 (95% CI 0.79 to 0.91)). Conclusion. The CPUP Hip Score had a high ability to discriminate between children at different levels of risk for displacement of the hip. The score overestimated the absolute risks of displacement in this population, which may have resulted from differences in the way children were initially registered in the two programmes. The results are promising, but the score weights may need re-estimation before its clinical application in Scotland. Cite this article: Bone Joint J 2022;104-B(5):640–644

Aims. The migration percentage (MP) is one criterion used for surgery in dislocated or displaced hips in children with cerebral palsy (CP). The MP at which a displaced hip can no longer return to normal is unclear. The aim of this paper was to identify the point of no return of the MP through a large population-based study. Methods. All children registered on the Cerebral Palsy Integrated Pathway Scotland surveillance programme undergo regular pelvic radiographs. Any child who had a MP measuring over 35% since the programme’s inception in 2013, in at least one hip and at one timepoint, was identified. The national radiography database was then interrogated to identify all pelvic radiographs for each of these children from birth through to the date of analysis. A minimum of a further two available radiographs following the initial measurement of MP ≥ 35% was required for inclusion. Results. A total of 239 children (346 hips) were identified as suitable for analysis at a mean of 6.5 years (2.0 to 14.8) follow-up. In all, 1,485 radiographs taken both prior to and after a hip had a MP ≥ 35% were examined and the MP measured to identify any progression of displacement. Interrogation of the data identified that hips with a MP up to 46% returned to a MP below 40% without intervention, and all hips with a MP equal to or greater than 46% displaced further and the MP did not return to the normal range. Statistical analysis showed the result to be 98% specific with this degree of certainty that hips reaching a MP ≥ 46% would not spontaneously regress. Conclusion. These findings are clinically relevant in showing that it may be reasonable to continue to monitor hips with a MP not exceeding 46%. This threshold will also guide referral for further management of a displacing hip. Cite this article: Bone Joint J 2021;103-B(2):411–414

Aims. We aimed to determine hip-related quality of life and clinical findings following treatment for neonatal hip instability (NHI) compared with age- and sex-matched controls. We hypothesized that NHI would predispose to hip discomfort in long-term follow-up. Methods. We invited those born between 1995 and 2001 who were treated for NHI at our hospital to participate in this population-based study. We included those that had Von Rosen-like splinting treatment started before one month of age. A total of 96 patients treated for NHI (75.6 %) were enrolled. A further 94 age- and sex-matched controls were also recruited. The Copenhagen Hip and Groin Outcome Score (HAGOS) questionnaire was completed separately for both hips, and a physical examination was performed. Results. The mean follow-up was 18.2 years (14.6 to 22.0). The HAGOS scores between groups were similar and met statistical and clinical significance only in the Symptoms subscale (mean difference 3.80, 95% confidence interval (CI) 0.31 to 7.29; p = 0.033). Those patients who had undergone treatment for NHI had a higher frequency of positive flexion-adduction-internal rotation test (odds ratio (OR) 2.6, 95% CI 1.2 to 5.6; p = 0.014), resisted straight leg rise test (OR 4.5, 95% CI 1.4 to 14.9; p = 0.014), and also experienced more pain in the groin during passive end range hip flexion (OR 2.5, 95% CI 1.2 to 5.3; p = 0.015) than controls. Conclusion. NHI predisposes to hip discomfort in clinical tests, but no clinically relevant differences in experience of pain, physical function, and hip-related quality of life could be observed between the treated group and matched controls in 18 years of follow-up. Cite this article: Bone Joint J 2020;102-B(12):1767–1773