An MRI-Based classification of osteonecrosis of the femoral head based on the spatial relationship between the epiphyseal line and osteonecrotic boundary.

OBJECTIVES

The purpose of this study is to propose a new classification of osteonecrosis of the femoral head (ONFH) based on the relationship between the epiphyseal line and osteonecrotic boundary, to offer a reference for prognostic assessment of ONFH and provide strategic guidance for hip surgical interventions.

MATERIALS AND

METHODS

This retrospective, single-center study commenced by gathering data on patients diagnosed with ONFH between June 2018 and May 2023. Patients were classified into five types based on the relationship between the epiphyseal line and the osteonecrotic boundary on magnetic resonance imaging coronal midsections. Various imaging findings, including bone marrow edema, cystic lesions, microfractures, collapse, and crescent signs, were assessed. Statistical analyses were performed to determine the association between this relationship and disease progression.

RESULTS

We researched 289 ONFH patients (42.53 years ± 13.66, 193 men) (405 hips) who met our selection criteria. Type A comprised 35.31 %, Type B 56.54 %, and Type C 8.15 %. Significant differences were observed among Types A, B, and C concerning the presence of cystic lesions, microfractures, collapse, and crescent signs (p < 0.001). Univariate logistic regression analysis demonstrates a progressive increase in structural impairment risks across classifications. Additionally, significant differences were also found in the subtypes of Type B (B1, B2, B3).

CONCLUSION

The relationship between the epiphyseal line and the osteonecrotic boundary is closely associated with the progression of ONFH, particularly in the development of femoral head collapse. This study introduced a novel imaging classification system for ONFH, providing valuable insights for clinical management.