Aims. Perthes’ disease (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

Purpose:. To examine the feasibility of surgical outcome measures for a children's orthopaedic surgeon when compared with other specialties. Methods & Results:. Details of procedure codes for 2726 inpatient episodes were used to examine the distribution of procedures and the breadth of diagnoses dealt with by a variety of orthopaedic sub-specialists. The author's practice included 199 surgical cases and was compared with two arthroplasty surgeons (n=971); a spinal surgeon (n=256); a foot and ankle surgeon (n=341) and an upper limb surgeon (n=393). Arthroplasty surgeons can report 50% of their outcomes as primary knee or hip replacements the index procedure for the author is metalwork removal (14.5%). My upper limb colleague could be judged on 25% of his cases (carpal tunnel decompression) and my spinal surgical colleague on 20% of his cases (primary posterior decompression of spinal cord). Only my foot and ankle colleague compared in terms of diversity with 9% of his cases consisting of first metatarsal osteotomy and the next 9% consisting of 1st MTPJ arthrodesis. The proportion of multiple procedures also varies between sub-specialists with 66% of my cases being multiple compared with 38% for the arthroplasty surgeons and 42% for the upper limb surgeons. Foot and ankle has a high rate of multiple procedures (62%) and the spinal surgeons code different procedures at each level in the spine giving the high rates of multiple procedures. Conclusion:. Outcome measures in children's orthopaedics seem problematic owing to the diverse nature of the practice and the confusion resulting from multiple procedures contributing to the outcome in 60% of cases. Either we are treated like physicians who do not have surgical outcomes to report or some goal based measure is adopted. Level of evidence: III