Geographic characterization of intra-articular pathologies in early-stage avascular necrosis of the hip

TL;DR

This study finds that early-stage hip avascular necrosis is often linked to specific joint pathologies, with higher disease stages showing more severe lesions.

Contribution

The study provides a detailed geographic analysis of intra-articular pathologies in early-stage hip AVN and compares MRI and arthroscopy diagnostic accuracy.

Findings

AVN most commonly affects zones 2 and 3 of the femoral head, where labral tears and cartilage lesions are frequent.

Higher Ficat stages correlate with increased prevalence of labral tears, cartilage lesions, and synovitis.

Arthroscopy is more sensitive than MRI for detecting grade 1 cartilage lesions in early-stage AVN.

Abstract

Avascular necrosis (AVN) of the hip is a progressive condition that often leads to femoral head collapse, necessitating total hip arthroplasty. While core decompression (CD) is commonly performed for the treatment of early-stage AVN, the incidence and geographic location of concomitant intra-articular pathologies that may contribute to symptoms and disease progression are incompletely understood.

The purpose of this study was to describe the prevalence, anatomical distribution, and diagnostic concordance of MRI vs. arthroscopy in detecting intra-articular pathology in early-stage AVN. We hypothesized that early-stage hip AVN would be associated with a high prevalence of intra-articular pathology in specific anatomic zones, and that higher Ficat stage would be associated with a greater frequency of these lesions.

Patients who underwent arthroscopic-assisted core decompression (CD) by two surgeons for symptomatic early-stage AVN between March 2020 and December 2024 were retrospectively identified. Preoperative radiographs and MRIs were reviewed by a fellowship-trained musculoskeletal radiologist to characterize AVN involvement of the femoral head, labral tears, chondral pathologies, and synovitis/effusion, using the geographic zone method. MRI interpretations were compared to intraoperative arthroscopic findings. Associations between the Ficat stage and the prevalence of intra-articular pathologies were assessed.

A total of 36 hips in 30 patients were analyzed. Among all hips analyzed, three (8.3%) were Ficat stage 1, 25 (69.4%) were Ficat stage 2a, and eight (22.2%) were Ficat stage 2b. AVN most affected zones 2 and 3 of the femoral head, which frequently corresponded to the locations of labral tears and acetabular transition zone chondral lesions. A high prevalence of labral tears (88.9%), acetabular cartilage lesions (75%), and synovitis (61.1%) was observed. MRI interpretations almost always correlated with arthroscopic findings, although arthroscopy was more sensitive in detecting grade 1 softening of the femoral head and acetabular cartilage. Higher Ficat stage was associated with a higher prevalence of labral tears (p=0.02), acetabular cartilage lesions (p<0.01), femoral head cartilage lesions (p<0.01), and synovitis/effusion (p=0.02).

Early-stage hip AVN is associated with a high prevalence of intra-articular pathologies, with increasing Ficat stage correlating with more frequent labral tears, transition zone and femoral head cartilage lesions, and synovitis/effusion. While MRI accurately identified and localized most intra-articular pathologies, arthroscopy was more sensitive for detecting grade 1 cartilage lesions.

Arthroscopic-assisted core decompression offers an opportunity to identify and treat intra-articular pathology that may contribute to pain and disease progression in early-stage hip AVN. Recognizing the high prevalence and location of these lesions may help optimize surgical decision-making and long-term outcomes.

Retrospective case series; Level of evidence, 4.

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