Abstract
Introduction
Subchondral insufficiency fracture (SIF) needs to be differentiated from osteonecrosis. The purpose of this study was to evaluate the imaging and histopathological findings of patients 60 years or older with radiological evidence of subchondral collapse of the femoral head.
Methods
We reviewed 77 consecutive hips in 56 patients aged 60 years or older, which showed subchondral collapse on radiographs. According to the shapes of low-intensity bands on T1-weighted images of magnetic resonance imaging (MRI), the patients were divided into 2 groups. Group A showed a concavity of the articular surface: characteristic appearances of osteonecrosis, and Group B showed an irregular convexity of the articular surface: characteristic appearances of SIF.
Results
Thirty-four patients (60.7%) were categorized as Group A and 22 patients (39.3%) as Group B. All the cases in Group A had a history of corticosteroid intake or alcohol abuse. In Group B, the proportion of women as well as unilateral involvement was significantly higher than those in Group A. In 30 cases with histopathological examination, 16 were in Group A and 14 were in Group B. All the cases in Group A demonstrated characteristic features of osteonecrosis. In Group B, the band on T1-weighted images corresponded to viable reparative tissue including granulation tissue and fracture callus, which are characteristic histological findings in SIF.
Conclusion
The results of this study suggest that the patient's clinical features as well as the shapes of the low-intensity bands on T1-weighted images provide a clinically concise tool for the differentiation of SIF from osteonecrosis.
