# Femoral head vascular status in early-stage Legg–Calvé–Perthes disease assessed by contrast-enhanced magnetic resonance imaging: comparison with the contralateral side

## TL;DR

This study uses MRI to assess blood flow in the femoral head of children with early-stage Legg–Calvé–Perthes disease, comparing it to the healthy side.

## Contribution

The study provides new insights into early vascular changes in the femoral head cartilage of children with LCPD.

## Key findings

- Increased and thickened cartilaginous vessels were observed in the affected femoral head.
- The lateral and medial parts showed the most significant vascular changes compared to other regions.
- Vascular changes were more pronounced in cartilage than in the ossification center.

## Abstract

Legg–Calvé–Perthes disease (LCPD) is characterized by avascular necrosis of the femoral head (FH) in children. FH blood supply restoration is important for understanding LCPD’s pathophysiology. We used gadolinium-enhanced magnetic resonance imaging (MRI) to clarify the early-stage FH vascular status in patients with stage I Waldenström LCPD.

This retrospective study included 23 patients diagnosed with unilateral LCPD using gadolinium-enhanced MRI between January 2017 and September 2024. The vascular evaluation of ossification centers was categorized into visible and invisible levels. Additionally, the axial FH cartilage was classified into medial, lateral, anterior, and posterior parts. Compared with the contralateral normal side, each part’s vascularity on the lesion side was categorized into reduced, comparable, and increased grades. Proportions of grades across parts were compared using Fisher’s exact test with Bonferroni correction. Blood vessel thickness was also assessed.

On the affected side, the FH vascular distribution was mainly concentrated within the cartilage, with the ossification center vessels observed in only seven cases. The proportions of patients with increased cartilaginous vessels in the medial, lateral, anterior, and posterior parts were 65.2%, 78.2%, 8.6%, and 26.0%, respectively. Statistically significant discrepancies were observed in the medial and lateral parts compared to the posterior and anterior parts. Thickened cartilaginous vessels were present in the lateral part of 78.2% of patients. The ratio was 60.8%, 17.3% and 34.7% in the medial, anterior, and posterior parts, respectively. Due to the prolonged LCPD course and absence of outcome data, we did not investigate the relationship between FH vascular status in the early stage and clinical outcomes of LCPD.

In patients with stage I Waldenström LCPD, the affected FH exhibits increased and thickened cartilaginous vessels, suggesting more pronounced vascular remodeling compared to the ossification center. The lateral and medial parts exhibited the most obvious cartilaginous vascular manifestation.

IV.