Advertisement for orthosearch.org.uk
Results 1 - 20 of 233
Results per page:
The Bone & Joint Journal
Vol. 107-B, Issue 1 | Pages 124 - 132
1 Jan 2025
Thompson P Khattak M Joseph PJ Perry DC Cootes TF Lindner C

Aims

The aims of this study were to develop an automatic system capable of calculating four radiological measurements used in the diagnosis and monitoring of cerebral palsy (CP)-related hip disease, and to demonstrate that these measurements are sufficiently accurate to be used in clinical practice.

Methods

We developed a machine-learning system to automatically measure Reimer’s migration percentage (RMP), acetabular index (ACI), head shaft angle (HSA), and neck shaft angle (NSA). The system automatically locates points around the femoral head and acetabulum on pelvic radiographs, and uses these to calculate measurements. The system was evaluated on 1,650 pelvic radiographs of children with CP (682 females and 968 males, mean age 8.3 years (SD 4.5)). Each radiograph was manually measured by five clinical experts. Agreement between the manual clinical measurements and the automatic system was assessed by mean absolute deviation (MAD) from the mean manual measurement, type 1 and type 2 intraclass correlation coefficients (ICCs), and a linear mixed-effects model (LMM) for assessing bias.


The Bone & Joint Journal
Vol. 107-B, Issue 1 | Pages 3 - 4
1 Jan 2025
Gelfer Y Ashby E Perry DC


The Bone & Joint Journal
Vol. 107-B, Issue 1 | Pages 42 - 49
1 Jan 2025
Kim HJ Yoon PW Cho E Jung I Moon J

Aims. We evaluated the national and regional trends from 2013 to 2022, in the prevalence of Perthesdisease 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 Perthesdisease 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 Perthesdisease prevalence and several related factors. Results. The prevalence of Perthesdisease 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 Perthesdisease, 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 Perthesdisease was highest in provinces, followed by the metropolitan area and Seoul. Conclusion. The prevalence of Perthesdisease in adolescent males increased over time from 2013 to 2022. In particular, the trend in the prevalence of Perthesdisease 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


The Bone & Joint Journal
Vol. 106-B, Issue 6 | Pages 555 - 564
1 Jun 2024
Leal J Holland CT Cochrane NH Seyler TM Jiranek WA Wellman SS Bolognesi MP Ryan SP

Aims

This study aims to assess the relationship between history of pseudotumour formation secondary to metal-on-metal (MoM) implants and periprosthetic joint infection (PJI) rate, as well as establish ESR and CRP thresholds that are suggestive of infection in these patients. We hypothesized that patients with a pseudotumour were at increased risk of infection.

Methods

A total of 1,171 total hip arthroplasty (THA) patients with MoM articulations from August 2000 to March 2014 were retrospectively identified. Of those, 328 patients underwent metal artefact reduction sequence MRI and had minimum two years’ clinical follow-up, and met our inclusion criteria. Data collected included demographic details, surgical indication, laterality, implants used, history of pseudotumour, and their corresponding preoperative ESR (mm/hr) and CRP (mg/dl) levels. Multivariate logistic regression modelling was used to evaluate PJI and history of pseudotumour, and receiver operating characteristic curves were created to assess the diagnostic capabilities of ESR and CRP to determine the presence of infection in patients undergoing revision surgery.


The Bone & Joint Journal
Vol. 106-B, Issue 5 | Pages 422 - 424
1 May 2024
Theologis T Perry DC

In 2017, the British Society for Children’s Orthopaedic Surgery engaged the profession and all relevant stakeholders in two formal research prioritization processes. In this editorial, we describe the impact of this prioritization on funding, and how research in children’s orthopaedics, which was until very recently a largely unfunded and under-investigated area, is now flourishing. Establishing research priorities was a crucial step in this process.

Cite this article: Bone Joint J 2024;106-B(5):422–424.


The Bone & Joint Journal
Vol. 106-B, Issue 5 Supple B | Pages 3 - 10
1 May 2024
Heimann AF Murmann V Schwab JM Tannast M

Aims

The aim of this study was to investigate whether anterior pelvic plane-pelvic tilt (APP-PT) is associated with distinct hip pathomorphologies. We asked: is there a difference in APP-PT between young symptomatic patients being evaluated for joint preservation surgery and an asymptomatic control group? Does APP-PT vary among distinct acetabular and femoral pathomorphologies? And does APP-PT differ in symptomatic hips based on demographic factors?

Methods

This was an institutional review board-approved, single-centre, retrospective, case-control, comparative study, which included 388 symptomatic hips in 357 patients who presented to our tertiary centre for joint preservation between January 2011 and December 2015. Their mean age was 26 years (SD 2; 23 to 29) and 50% were female. They were allocated to 12 different morphological subgroups. The study group was compared with a control group of 20 asymptomatic hips in 20 patients. APP-PT was assessed in all patients based on supine anteroposterior pelvic radiographs using validated HipRecon software. Values in the two groups were compared using an independent-samples t-test. Multiple regression analysis was performed to examine the influences of diagnoses and demographic factors on APP-PT. The minimal clinically important difference (MCID) for APP-PT was defined as > 1 SD.


The Bone & Joint Journal
Vol. 106-B, Issue 5 Supple B | Pages 40 - 46
1 May 2024
Massè A Giachino M Audisio A Donis A Giai Via R Secco DC Limone B Turchetto L Aprato A

Aims. Ganz’s studies made it possible to address joint deformities on both the femoral and acetabular side brought about by Perthesdisease. Femoral head reduction osteotomy (FHRO) was developed to improve joint congruency, along with periacetabular osteotomy (PAO), which may enhance coverage and containment. The purpose of this study is to show the clinical and morphological outcomes of the technique and the use of an implemented planning approach. Methods. From September 2015 to December 2021, 13 FHROs were performed on 11 patients for Perthesdisease in two centres. Of these, 11 hips had an associated PAO. A specific CT- and MRI-based protocol for virtual simulation of the corrections was developed. Outcomes were assessed with radiological parameters (sphericity index, extrusion index, integrity of the Shenton’s line, lateral centre-edge angle (LCEA), Tönnis angle), and clinical parameters (range of motion, visual analogue scale (VAS) for pain, Merle d'Aubigné-Postel score, modified Harris Hip Score (mHHS), and EuroQol five-dimension five-level health questionnaire (EQ-5D-5L)). Early and late complications were reported. Results. The mean follow-up was 39.7 months (standard deviation (SD) 26.4). The mean age at surgery was 11.4 years (SD 1.6). No major complications were recorded. One patient required a total hip arthroplasty. Mean femoral head sphericity increased from 46.8% (SD 9.34%) to 70.2% (SD 15.44; p < 0.001); mean LCEA from 19.2° (SD 9.03°) to 44° (SD 10.27°; p < 0.001); mean extrusion index from 37.8 (SD 8.70) to 7.5 (SD 9.28; p < 0.001); and mean Tönnis angle from 16.5° (SD 12.35°) to 4.8° (SD 4.05°; p = 0.100). The mean VAS improved from 3.55 (SD 3.05) to 1.22 (1.72; p = 0.06); mean Merle d’Aubigné-Postel score from 14.55 (SD 1.74) to 16 (SD 1.6; p = 0.01); and mean mHHS from 60.6 (SD 18.06) to 81 (SD 6.63; p = 0.021). The EQ-5D-5L also showed significant improvements. Conclusion. FHRO associated with periacetabular procedures is a safe technique that showed improved functional, clinical, and morphological outcomes in Perthesdisease. The newly introduced simulation and planning algorithm may help to further refine the technique. Cite this article: Bone Joint J 2024;106-B(5 Supple B):40–46


The Bone & Joint Journal
Vol. 106-B, Issue 5 Supple B | Pages 1 - 2
1 May 2024
Berry DJ Haddad FS


The Bone & Joint Journal
Vol. 106-B, Issue 5 | Pages 501 - 507
1 May 2024
Galloway AM Keene DJ Anderson A Holton C Redmond AC Siddle HJ Richards S Perry DC

Aims. The aim of this study was to produce clinical consensus recommendations about the non-surgical treatment of children with Perthesdisease. 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 Perthesdisease 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 Perthesdisease and their families. Conclusion. Children’s orthopaedic specialists have reached consensus on recommendations for non-surgical treatment in Perthesdisease. 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


The Bone & Joint Journal
Vol. 106-B, Issue 3 | Pages 277 - 285
1 Mar 2024
Pinto D Hussain S Leo DG Bridgens A Eastwood D Gelfer Y

Aims

Children with spinal dysraphism can develop various musculoskeletal deformities, necessitating a range of orthopaedic interventions, causing significant morbidity, and making considerable demands on resources. This systematic review aimed to identify what outcome measures have been reported in the literature for children with spinal dysraphism who undergo orthopaedic interventions involving the lower limbs.

Methods

A PROSPERO-registered systematic literature review was performed following PRISMA guidelines. All relevant studies published until January 2023 were identified. Individual outcomes and outcome measurement tools were extracted verbatim. The measurement tools were assessed for reliability and validity, and all outcomes were grouped according to the Outcome Measures Recommended for use in Randomized Clinical Trials (OMERACT) filters.


The Bone & Joint Journal
Vol. 106-B, Issue 2 | Pages 121 - 127
1 Feb 2024
Filtes P Sobol K Lin C Anil U Roberts T Pargas-Colina C Castañeda P

Aims. Perthes' disease (PD) is a relatively rare syndrome of idiopathic osteonecrosis of the proximal femoral epiphysis. Treatment for Perthes' disease is controversial due to the many options available, with no clear superiority of one treatment over another. Despite having few evidence-based approaches, many patients with Perthes' disease are managed surgically. Positive outcome reporting, defined as reporting a study variable producing statistically significant positive (beneficial) results, is a phenomenon that can be considered a proxy for the strength of science. This study aims to conduct a systematic literature review with the hypothesis that positive outcome reporting is frequent in studies on the treatment of Perthes' disease. Methods. We conducted a systematic review of all available abstracts associated with manuscripts in English or with English translation between January 2000 and December 2021, dealing with the treatment of Perthes' disease. Data collection included various study characteristics, surgical versus non-surgical management, treatment modality, mean follow-up time, analysis methods, and clinical recommendations. Results. Our study included 130 manuscripts. Overall, 110 (85%) reported positive (beneficial) results, three (2%) reported negative results, and 17 (13%) reported no significant difference. Despite only 10/130 studies (8%) having a testable hypothesis, 71 (55%) recommended the use of their studied treatment methods for the patients, five (4%) made recommendations against the use of the studied treatment modality, and 54 (42%) did not make any recommendations. Conclusion. The overall rate for positive outcomes among included manuscripts regarding different treatment methods for Perthes' disease (85%) is higher than the 74% positive outcome rate found among studies for other surgically treated disorders and significantly higher than most scientific literature. Despite the lack of testable hypotheses, most manuscripts recommended their studied treatment method as a successful option for managing patients solely based on the reporting of retrospective data. Cite this article: Bone Joint J 2024;106-B(2):121–127


The Bone & Joint Journal
Vol. 105-B, Issue 7 | Pages 735 - 742
1 Jul 2023
Andronic O Germann C Jud L Zingg PO

Aims

This study reports mid-term outcomes after periacetabular osteotomy (PAO) exclusively in a borderline hip dysplasia (BHD) population to provide a contrast to published outcomes for arthroscopic surgery of the hip in BHD.

Methods

We identified 42 hips in 40 patients treated between January 2009 and January 2016 with BHD defined as a lateral centre-edge angle (LCEA) of ≥ 18° but < 25°. A minimum five-year follow-up was available. Patient-reported outcomes (PROMs) including Tegner score, subjective hip value (SHV), modified Harris Hip Score (mHHS), and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) were assessed. The following morphological parameters were evaluated: LCEA, acetabular index (AI), α angle, Tönnis staging, acetabular retroversion, femoral version, femoroepiphyseal acetabular roof index (FEAR), iliocapsularis to rectus femoris ratio (IC/RF), and labral and ligamentum teres (LT) pathology.


The Bone & Joint Journal
Vol. 105-B, Issue 6 | Pages 711 - 716
1 Jun 2023
Ali MS Khattak M Metcalfe D Perry DC

Aims. This study aimed to evaluate the relationship between hip shape and mid-term function in Perthesdisease. It also explored whether the modified three-group Stulberg classification can offer similar prognostic information to the five-group system. Methods. A total of 136 individuals aged 12 years or older who had Perthesdisease in childhood completed the Patient-Reported Outcomes Measurement Information System (PROMIS) Mobility score (function), Nonarthritic Hip Score (NAHS) (function), EuroQol five-dimension five-level questionnaire (EQ-5D-5L) score (quality of life), and the numeric rating scale for pain (NRS). The Stulberg class of the participants’ hip radiographs were evaluated by three fellowship-trained paediatric orthopaedic surgeons. Hip shape and Stulberg class were compared to PROM scores. Results. A spherical hip was associated with the highest function and quality of life, and lowest pain. Conversely, aspherical hips exhibited the lowest functional scores and highest pain. The association between worsening Stulberg class (i.e. greater deviation from sphericity) and worse outcome persisted after adjustment for age and sex in relation to PROMIS (predicted mean difference -1.77 (95% confidence interval (CI) -2.70 to -0.83)), NAHS (-5.68 (95% CI -8.45 to -2.90)), and NRS (0.61 (95% CI 0.14 to 1.08)), but not EQ-5D-5L (-0.03 (95% CI -0.72 to 0.11)). Conclusion. Patient-reported outcomes identify lower function, quality of life, and higher pain in aspherical hips. The magnitude of symptoms deteriorated with time. Hip sphericity (i.e. the modified three-group classification of spherical, oval, and aspherical) appeared to offer similar levels of detail to the five-group Stulberg classification. Cite this article: Bone Joint J 2023;105-B(6):711–716


The Bone & Joint Journal
Vol. 104-B, Issue 12 | Pages 1304 - 1312
1 Dec 2022
Kim HKW Almakias R Millis MB Vakulenko-Lagun B

Aims. Perthesdisease (PD) is a childhood hip disorder that can affect the quality of life in adulthood due to femoral head deformity and osteoarthritis. There is very little data on how PD patients function as adults, especially from the patients’ perspective. The purpose of this study was to collect treatment history, demographic details, the University of California, Los Angeles activity score (UCLA), the 36-Item Short Form survey (SF-36) score, and the Hip disability and Osteoarthritis Outcome score (HOOS) of adults who had PD using a web-based survey method and to compare their outcomes to the outcomes from an age- and sex-matched normative population. Methods. The English REDCap-based survey was made available on a PD study group website. The survey included childhood and adult PD history, UCLA, SF-36, and HOOS. Of the 1,182 participants who completed the survey, the 921 participants who did not have a total hip arthroplasty are the focus of this study. The mean age at survey was 38 years (SD 12) and the mean duration from age at PD onset to survey participation was 30.8 years (SD 12.6). Results. In comparison to a normative population, the PD participants had significantly lower HOOS scores across all five scales (p < 0.001) for all age groups. Similarly, SF-36 scores of the participants were significantly lower (p < 0.001) for all scales except for age groups > 55 years. Overall, females, obese participants, those who reported no treatment in childhood, and those with age of onset > 11 years had significantly worse SF-36 and HOOS scores. Pairwise correlations showed a strong positive correlation within HOOS scales and between HOOS scales and SF-36 scales, indicating construct validity. Conclusion. Adult PD participants had significantly worse pain, physical, mental, and social health than an age- and sex-matched normative cohort. The study reveals a significant burden of disease on the adult participants of the survey, especially females. Cite this article: Bone Joint J 2022;104-B(12):1304–1312


The Bone & Joint Journal
Vol. 104-B, Issue 9 | Pages 1017 - 1024
1 Sep 2022
Morris WZ Justo PGS Williams KA Kim Y Millis MB Novais EN

Aims

The aims of this study were to characterize the incidence and risk factors associated with stress fractures following periacetabular osteotomy, and to determine their effect on osteotomy union.

Methods

We retrospectively reviewed all periacetabular osteotomies (PAOs) performed for developmental dysplasia of the hip (DDH) at one institution over a six-year period between 2012 and 2017. Perioperative factors were recorded, and included demographic and surgical data. Postoperatively, patients were followed for a minimum of one year with anteroposterior and false profile radiographs of the pelvis to monitor for evidence of stress fracture and union of osteotomies. We characterized the incidence and locations of stress fractures, and used univariate and multivariable analysis to identify factors predictive of stress fracture and the association of stress fracture on osteotomy union.


The Bone & Joint Journal
Vol. 104-B, Issue 9 | Pages 1032 - 1038
1 Sep 2022
García-Rey E Cruz-Pardos A Saldaña L

Aims

A significant reduction in wear at five and ten years was previously reported when comparing Durasul highly cross-linked polyethylene with nitrogen-sterilized Sulene polyethylene in total hip arthroplasty (THA). We investigated whether the improvement observed at the earlier follow-up continued, resulting in decreased osteolysis and revision surgery rates over the second decade.

Methods

Between January 1999 and December 2001, 90 patients underwent surgery using the same acetabular and femoral components with a 28 mm metallic femoral head and either a Durasul or Sulene liner. A total of 66 hips of this prospective randomized study were available for a minimum follow-up of 20 years. The linear femoral head penetration rate was measured at six weeks, one year, and annually thereafter, using the Dorr method on digitized radiographs with a software package.


The Bone & Joint Journal
Vol. 104-B, Issue 4 | Pages 510 - 518
1 Apr 2022
Perry DC Arch B Appelbe D Francis P Craven J Monsell FP Williamson P Knight M

Aims. The aim of this study was to evaluate the epidemiology and treatment of Perthesdisease of the hip. Methods. This was an anonymized comprehensive cohort study of Perthesdisease, with a nested consented cohort. A total of 143 of 144 hospitals treating children’s hip disease in the UK participated over an 18-month period. Cases were cross-checked using a secondary independent reporting network of trainee surgeons to minimize those missing. Clinician-reported outcomes were collected until two years. Patient-reported outcome measures (PROMs) were collected for a subset of participants. Results. Overall, 371 children (396 hips) were newly affected by Perthesdisease arising from 63 hospitals, with a median of two patients (interquartile range 1.0 to 5.5) per hospital. The annual incidence was 2.48 patients (95% confidence interval (CI) 2.20 to 2.76) per 100,000 zero- to 14-year-olds. Of these, 117 hips (36.4%) were treated surgically. There was considerable variation in the treatment strategy, and an optimized decision tree identified joint stiffness and age above eight years as the key determinants for containment surgery. A total of 348 hips (88.5%) had outcomes to two years, of which 227 were in the late reossification stage for which a hip shape outcome (Stulberg grade) was assigned. The independent predictors of a poorer radiological outcome were female sex (odds ratio (OR) 2.27 (95% CI 1.19 to 4.35)), age above six years (OR 2.62 (95% CI (1.30 to 5.28)), and over 50% radiological collapse at inclusion (OR 2.19 (95% CI 0.99 to 4.83)). Surgery had no effect on radiological outcomes (OR 1.03 (95% CI 0.55 to 1.96)). PROMs indicated the marked effect of the disease on the child, which persisted at two years. Conclusion. Despite the frequency of containment surgery, we found no evidence of improved outcomes. There appears to be a sufficient case volume and community equipoise among surgeons to embark on a randomized clinical trial to definitively investigate the effectiveness of containment surgery. Cite this article: Bone Joint J 2022;104-B(4):510–518


The Bone & Joint Journal
Vol. 103-B, Issue 12 | Pages 1815 - 1820
1 Dec 2021
Huhnstock S Wiig O Merckoll E Svenningsen S Terjesen T

Aims. The aim of this study was to assess the prognostic value of the modified three-group Stulberg classification, which is based on the sphericity of the femoral head, in patients with Perthesdisease. Methods. A total of 88 patients were followed from the time of diagnosis until a mean follow-up of 21 years. Anteroposterior pelvic and frog-leg lateral radiographs were obtained at diagnosis and at follow-up of one, five, and 21 years. At the five- and 21-year follow-up, the femoral heads were classified using a modified three-group Stulberg classification (round, ovoid, or flat femoral head). Further radiological endpoints at long-term follow-up were osteoarthritis (OA) of the hip and the requirement for total hip arthroplasty (THA). Results. There were 71 males (81%) and 17 females. A total of 13 patients had bilateral Perthesdisease; thus 101 hips were analyzed. At five-year follow-up, 37 hips were round, 38 ovoid, and 26 flat. At that time, 66 hips (65%) were healed and 91 (90%) were skeletally immature. At long-term follow-up, when the mean age of the patients was 28 years (24 to 34), 20 hips had an unsatisfactory outcome (seven had OA and 13 had required THA). There was a strongly significant association between the modified Stulberg classification applied atfive-year follow-up and an unsatisfactory outcome at long-term follow-up (p < 0.001). Between the five- and 21-year follow-up, 67 hips (76%) stayed in their respective modified Stulberg group, indicating a strongly significant association between the Stulberg classifications at these follow-ups (p < 0.001). Conclusion. The modified Stulberg classification is a strong predictor of long-term radiological outcome in patients with Perthesdisease. It can be applied at the healing stage, which is usually reached five years after the diagnosis is made and before skeletal maturity. Cite this article: Bone Joint J 2021;103-B(12):1815–1820


The Bone & Joint Journal
Vol. 103-B, Issue 11 | Pages 1642 - 1645
1 Nov 2021
Kayani B Giebaly D Haddad FS


The Bone & Joint Journal
Vol. 103-B, Issue 11 | Pages 1736 - 1741
1 Nov 2021
Tolk JJ Eastwood DM Hashemi-Nejad A

Aims. Perthesdisease (PD) often results in femoral head deformity and leg length discrepancy (LLD). Our objective was to analyze femoral morphology in PD patients at skeletal maturity to assess where the LLD originates, and evaluate the effect of contralateral epiphysiodesis for length equalization on proximal and subtrochanteric femoral lengths. Methods. All patients treated for PD in our institution between January 2013 and June 2020 were reviewed retrospectively. Patients with unilateral PD, LLD of ≥ 5 mm, and long-leg standing radiographs at skeletal maturity were included. Total leg length, femoral and tibial length, articulotrochanteric distance (ATD), and subtrochanteric femoral length were compared between PD side and the unaffected side. Furthermore, we compared leg length measurements between patients who did and who did not have a contralateral epiphysiodesis. Results. Overall, 79 patients were included, of whom 21 underwent contralateral epiphysiodesis for leg length correction. In the complete cohort, the mean LLD was 1.8 cm (95% confidence interval (CI) 1.5 to 2.0), mean ATD difference was 1.8 cm (95% CI -2.1 to -1.9), and mean subtrochanteric difference was -0.2 cm (95% CI -0.4 to 0.1). In the epiphysiodesis group, the mean LLD before epiphysiodesis was 2.7 cm (95% CI 1.3 to 3.4) and 1.3 cm (95% CI -0.5 to 3.8) at skeletal maturity. In the nonepiphysiodesis group the mean LLD was 2.0 cm (95% CI 0.5 to 5.1; p = 0.016). The subtrochanteric region on the PD side was significantly longer at skeletal maturity in the epiphysiodesis group compared to the nonepiphysiodesis group (-1.0 cm (95% CI -2.4 to 0.6) vs 0.1 cm (95% CI -1.0 to 2.1); p < 0.001). Conclusion. This study demonstrates that LLD after PD originates from the proximal segment only. In patients who had contralateral epiphysiodesis to balance leg length, this is achieved by creating a difference in subtrochanteric length. Arthroplasty surgeons need to be aware that shortening of the proximal femur segment in PD patients may be misleading, as the ipsilateral subtrochanteric length in these patients can be longer. Therefore, we strongly advise long-leg standing films for THA planning in PD patients in order to avoid inadvertently lengthening the limb. Cite this article: Bone Joint J 2021;103-B(11):1736–1741