Background: The prognosis of Legg-Calvé-Perthes disease (LCPD) is dependent upon several factors, with the length and severity of the fragmentation stage among the most important. Previous retrospectively collected data from a single center have suggested that early proximal femoral varus osteotomy (PFO) may shorten the length of fragmentation and allow 34% of patients to bypass fragmentation altogether resulting in less femoral head deformity. The purpose of this study was to validate these findings in a prospectively collected multicenter cohort. Methods: Patients with LCPD treated with early PFO (during Waldenström stage I) were prospectively followed with serial radiographs at 3-month intervals until a minimum of 2-year follow-up. Waldenström stages and lateral pillar class were determined by mode assessments from 3 pediatric orthopaedic surgeons. The duration of fragmentation was defined as the interval between the first radiographs demonstrating features of stage IIa and stage IIIa. “Complete” bypass was defined as the absence of stage IIa or IIb findings on sequential radiographs with no development of femoral head deformity or collapse. “Partial” bypass was defined as the absence of advanced features of fragmentation and femoral head collapse (stage IIb). Results: Forty-six patients (80% male individuals) with initial stage LCPD and a mean age of 8.2±1.2 years were identified. The weighted kappa statistics for Waldenström staging and lateral pillar classifications showed excellent (0.833) and substantial (0.707) agreement, respectively. Ninety-eight percent of patients (45/46) underwent some period of fragmentation lasting between 91 and 518 days; the median duration was 206 days (interquartile range, 181 to 280). One patient (2%) bypassed fragmentation completely; 8 patients (17%) demonstrated partial bypass. Patients who completely or partially bypassed fragmentation experienced significantly less severe lateral pillar collapse (P=0.016) and shorter fragmentation duration (P=0.001). Conclusions: In this prospective multicenter cohort, we found a lower rate of fragmentation bypass than previously reported. Nonetheless, our data support the previous contention that early PFO may shorten fragmentation and minimize collapse in LCPD compared with historical controls. Further study with larger cohorts and a more rigorous definition of what constitutes bypass is warranted to clarify the effect of early PFO on the reparative biology of LCPD. Level of Evidence: Level IV—therapeutic study.

Background Weightbearing and activity restrictions are commonly prescribed during the active stages of Perthes disease. These restrictions, ranging from cast or brace treatment with nonweightbearing to full weightbearing with activity restrictions, may have a substantial influence on the physical, mental, and social health of a child. However, their impact on the patient’s quality of life is not well-described. Questions/purposes After controlling for confounding variables, we asked (1) are restrictions on weightbearing and activity associated with physical health measures (as expressed by the Patient-Reported Outcome Measurement Information System [PROMIS] mobility, PROMIS pain interference, and PROMIS fatigue) of children in the active stages of Perthes disease? (2) Are these restrictions associated with poorer scores for mental health measures (PROMIS depressive symptoms and PROMIS anxiety)? (3) Are these restrictions associated with poorer scores for social health measures (PROMIS peer relationships)? Methods Between 2013 and 2020, 211 patients with Perthes disease at a single institution were assigned six PROMIS measures to assess physical, mental, and social health. Patients who met the following eligibility criteria were analyzed: age 8 to 14 years old, completion of six PROMIS measures, English-speaking, and active stage of Perthes disease (Waldenstrom Stage I, II, or III). Weightbearing and activity restrictions were clinically recommended to patients in the initial through early reossification stages of Perthes disease when patients had increasing pain, loss of hip motion, loss of hip containment, progression of femoral head deformity, increased hip synovitis, and femoral head involvement on MRI or as a postoperative regimen. Patients were categorized into four intervention groups based on weightbearing and activity regimen. We excluded 111 patients who did not meet the inclusion criteria. The following six pediatric self-report PROMIS measures were assessed: mobility, pain interference, fatigue, depressive symptoms, anxiety, and peer relationships. Of the 100 patients, 36 were categorized into the no-restriction regimen, 27 into the mild-restriction regimen, 25 into the moderate-restriction regimen, and 12 into the severe-restriction regimen at the time of PROMIS administration. The median (range) age at diagnosis was 8 years old (range 2 to 13 years). There were 85 boys and 15 girls. Eleven patients had hips in Waldenstrom Stage I, 10 were in Stage II, and 79 were in Stage III. Forty-four patients had hips classified as lateral pillar B and 47 patients as lateral pillar C. Nine patients had not reached the mid-fragmentation stage for appropriate lateral pillar classification by the time they took the PROMIS survey. ANOVA was used to compare differences between the mean PROMIS T-scores of these weightbearing/activity regimens. Results were assessed with a significance of p < 0.05 and adjusted for Waldenstrom stage, gender, age at diagnosis, and history of major surgery using multivariate regression analysis. Results After controlling for confounding variables, the mild- (β regression coefficient -15 [95% CI -19 to -10]; p < 0.001), moderate- (β -19 [95% CI -24 to -14]; p < 0.001), and severe- (β -25 [95% CI -30 to -19]; p < 0.001) restriction groups were associated with worse mobility T-scores compared with the no-restriction group, but no association was detected for the pain interference or fatigue measures. Weightbearing and activity restrictions were not associated with mental health measures (depressive symptoms and anxiety). Weightbearing and activity restrictions were not associated with social health measures (peer relationships). Earlier Waldenstrom stage was associated with worse pain interference (β 10 [95% CI 2 to 17]; p = 0.01) and peer relationships scores (β -8 [95% CI -15 to -1]; p = 0.03); female gender was linked with worse depressive symptoms (β 7 [95% CI 2 to 12]; p = 0.005) and peer relationships scores (β -6 [95% CI -12 to 0]; p = 0.04); and earlier age at diagnosis was associated with worse peer relationships scores (β 1 [95% CI 0 to 2]; p = 0.03). History of major surgery had no connection to any of the six PROMIS measures. Conclusion We found that weightbearing and activity restriction treatments are associated with poorer patient-reported mobility in the active stages of Perthes disease after controlling for Waldenstrom stage, gender, age at diagnosis, and history of surgery. Weightbearing/activity restrictions, however, are not associated with pain interference, fatigue, depressive symptoms, anxiety, and peer relationships. Understanding how these treatments are associated with quality of life in patients with Perthes disease can aid in decision-making for providers, help set expectations for patients and their parents, and provide opportunities for better education and preparation. Because of the chronic nature of Perthes disease, future studies may focus on longitudinal trends in patient-reported outcomes to better understand the overall impact of this disease and its treatment. Level of Evidence Level III, therapeutic study.