Radiographic classification and treatment of fibrous dysplasia of the proximal femur: 227 femurs with a mean follow-up of 6 years

Abstract

BackgroundResearch into the optimal treatment of fibrous dysplasia has been limited by the lack of an established classification system for the disease. The purposes of this study were to develop a radiographic classification for fibrous dysplasia of the proximal femur and to test this classification’s intra- and interobserver reliability as well as the effectiveness of our treatments.MethodsWe retrospectively reviewed radiographs and computed tomography (CT) of 227 femurs from 206 patients with fibrous dysplasia. The radiographs were evaluated in the coronal plane for neck-shaft angle, varus deformity in the proximal femoral shaft, and distal juxtaarticular valgus deformity. CT was evaluated in the axial plane for destruction of cortex. Reduction of bone strength was defined as the thickness of the remaining cortex less than 50 % of the original on axial CT. Two senior orthopedists evaluated each radiograph and CT twice at 8-week intervals. Intra- and interobserver reliability testing was performed using the kappa statistic. Treatments were assessed through mid-term follow-up.ResultsThe 227 femurs were classified into five reproducible types: type 1 (33 %), normal bone strength without angular deformity; type 2 (30 %), decreased bone strength without angular deformity; type 3 (12 %), isolated coxa vara with neck-shaft angle <120°; type 4 (11 %), isolated varus deformity in the proximal femoral shaft; and type 5 (14 %), coxa vara with varus deformity in the proximal femoral shaft. Intra- and interobserver kappa values were excellent, ranging from 0.85 to 0.88. Good clinical outcomes were achieved.ConclusionsThis radiographic classification of fibrous dysplasia is reproducible and useful for describing and assessing this disease. The treatments based on this classification were effective.

First application of three-dimensional designing total hip arthroplasty with long uncemented stem for fibrous dysplasia patients combined with hip joint osteoarthritis

“…However, Ippolito’s classification has a major limitation, which is the surgeons cannot determine osteotomy site or internal fixation method according to this classification. In 2015, our institution reported a novel method of radiographic classification including five types according to three parameters: neck-shaft angle, varus deformity of the proximal femoral shaft, and reduction in proximal femoral strength [10]. In our series, according to our institution’s classification, there were two type 2 patients, three type 3 patients, three type 4 patients, and four type 5 patients.…”

“…All patients underwent X-ray, three-dimensional computed tomography (3D-CT) and bone scintigraphy. According to our institution’s radiographic classification of FD in the proximal femur [10], there were two type 2 patients, three type 3 patients, three type 4 patients, and four type 5 patients (Table 1).…”

The Modified West China Hospital Radiographic Classification for Fibrous Dysplasia in Femur: A Retrospective Analysis of 238 Patients

“…Furthermore, their corresponding management was recommended. Currently, there have been only two prior systematic categories [8,11], which classify a variety of proximal femoral deformities in FD. However, both classi cations were failed to guide the most appropriate strategy for treatment.…”

“…The highest percentage of mistakes was made when distinguishing mild shepherd's crook deformity from severe shepherd's crook deformity. In our primary classi cation system [11], two senior orthopedic surgeons evaluated the cases for two rounds with a 6-week interval. The intraobserver and interobserver agreements were both excellent.…”

“…The surgical strategy is aimed at bone pain relief [9], restoring normal femoral alignment [5], gait normalization [6], LLD [5], and preventing pathological fracture [4,10] for FD patients. Based on our early experience in assessing deformities and pairing treatment strategies [6,11,12], we modi ed our previous classi cation into ve types following corresponding treatment options, which were as follows: including proximal femur bone loss, neck-shaft angle, femoral shaft deformity, genu valgum, and arthritis of hip. This study aimed to investigate the interobserver reliability and intraobserver reliability of our system and to evaluate the outcomes of surgical procedures based on our classi cation system that pair surgical strategy.…”