Does Early Proximal Femoral Varus Osteotomy Shorten the Duration of Fragmentation in Perthes Disease? Lessons From a Prospective Multicenter Cohort

Abstract

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.

Evolution of Legg-Calvé-Perthes disease following proximal femoral varus osteotomy performed in the avascular necrosis stage: A prospective study

“…One of the major shortcomings of this study is the small sample size, despite the fact that data collection extended over five years and it is likely that the differences in variables between the groups did not reach statistical significance on account of this. Though we could have included data of a larger number of children from the multi-centric database used in the study of Sankar et al 10 we opted not to do so. The reason for restricting the subjects to a single centre was because we felt it was important to have exactly the same treatment and the same post-operative protocol for all patients.…”

“…[6][7][8][9] Though these observations need further scrutiny, little new information regarding the phenomenon of bypassing fragmentation has appeared in the recent literature. 10 A very recent study 10 addressed the frequency of this phenomenon and concluded by stating that 'a more rigorous definition of what constitutes bypass is warranted'. This prompted us to undertake this prospective study to look more closely at the patterns of evolution of LCPD following containment surgery in stage Ia or Ib of the disease by a proximal femoral varus osteotomy.…”

Bypass of Epiphyseal Fragmentation Following Early Salter Innominate Osteotomy and Its Clinical Relevance in Legg-Calvé-Perthes Disease

“…Second, because of the retrospective nature of the study, the intervals between serial radiographs were not standardized, probably leading to a greater overestimation of the actual stage duration than other prospective studies. 8,9 All school-aged patients, however, were examined every long holiday twice or 3 times a year until skeletal maturity, and patients and their parents were usually requested to visit 1 or 2 more times during the school day until implant removal. This examination schedule corresponds to 3 or 4-month intervals during the active stage of the disease and afterward at least 6 months intervals, being comparable with that of other prospective studies.…”

“…However, it is uncertain whether the phenomenon denotes complete bypass only or both complete and incomplete bypass. More recently, one prospective multicenter study, consisting of 46 patients, demonstrated that complete or incomplete bypass was observed in 2% or 17% of patients, respectively, who had been treated during the avascular necrosis stage 8. According to another prospective study, which classified epiphyseal fragmentation into 4 patterns, of 25 patients who received early FVO, complete bypassing was observed in 12%, and abortive fragmentation was done in 24% 9.…”

The Long-Term Prognostic Value of Bone Scintigraphy in Legg-Calvé-Perthes Disease

“…To the best of our knowledge, this is the first study to show the long-term follow-up prognostic value of an advanced imaging method classification system applied in the initial stage of LCPD. Previous bone scan investigations showed the short-term correlation of the revascularization patterns with several radiographic classifications and outcome measures, but no long-term follow up study was further published [22,[31][32][33][34]. Advanced MRI techniques still lack long-term followup studies.…”