Analysis of Trabecular Microstructure and Vascular Distribution of Capital Femoral Epiphysis Relevant to Legg–Calve–Perthes Disease

Abstract

Legg-Calve-Perthes disease is characterized by the capital femoral epiphyseal collapse, which occurs more reliably in the anterior quadrant than the more weight-bearing lateral quadrant. The purpose of this study was to determine whether there is a vascular or microstructural predisposition for anterior femoral epiphyseal collapse in Perthes disease. Thirty-two cadaveric proximal femoral epiphyses from 17 subjects (age 4-14 years old) underwent micro-computed tomography at 10-μm resolution. Each quadrant was analyzed for four markers of trabecular architecture: bone volume fraction (BV/TV), trabecular thickness, trabecular separation (TbSp), and trabecular number (TbN). Vascular channels were then mapped in each quadrant, identified by correlating surface topography with cross-sectional imaging. One-way analysis of variance revealed an overall difference between quadrants (p < 0.001) in BV/TV, TbN, and TbSp. However, post hoc analysis revealed there was no significant difference between the anterior and lateral quadrants for any of the four markers of trabecular architecture. Vascular channel mapping illustrated a predominance of vessels in the posterior half of the epiphysis compared to the anterior half (8.7 ± 4.0 vs. 3.4 ± 3.1 vascular channels, p < 0.001). The lack of microstructural differences between the anterior and lateral quadrants, and the predominance of vascular channels in the posterior half of the epiphysis with posteriorly-based medial femoral circumflex and ligamentum teres vessels suggests that the anterior femoral epiphysis may be a relative vascular watershed region, which predisposes it to collapse after the vascular insult of Perthes disease. Clinical significance: Improved understanding of the pathophysiology of anterior femoral epiphyseal collapse may inform future treatments aimed at revascularization.

The Role of the Artery of Ligamentum Teres in Revascularization in Legg-Calve-Perthes Disease

“…Cadaveric studies identified the MFCA as the primary source of perfusion to the CFE, however, there is controversy in the literature with regards to the role of the artery of ligamentum teres. [1][2][3][4][5] The presence of separate and distinct areas of perfusion in the medial and lateral CFE provides further evidence of the important role of the ligamentum teres vessels in revascularization during the early stages of LCPD. In Waldenström stages I and IIa, ∼50% hips in both groups demonstrated separate medial and lateral sources of perfusion in the CFE.…”

“…Although the precise mechanism of vascular insult in LCPD remains unknown, there is growing literature characterizing the process of revascularization of the femoral head. Cadaveric studies identified the MFCA as the primary source of perfusion to the CFE, however, there is controversy in the literature with regards to the role of the artery of ligamentum teres 1–5…”

“…1,2 A more recent cadaveric study utilizing microcomputed tomography (microCT) of the capital femoral epiphysis (CFE) demonstrated preservation of perforating vascular channels at both the posterolateral location of the MFCA and the posteromedial location of the artery of ligamentum teres in the majority of hips, with prevalence of the ligamentum teres vascular channels increasing with age. 3 However, this study was performed in processed cadaveric specimens and could not reveal whether there was active perfusion through these vascular channels. Limited studies have utilized superselective angiography and intraosseous venogram to examine the role of ligamentum teres vasculature in the revascularization process of LCPD.…”

“…Historical cadaveric data suggested that perfusion of the immature femoral head occurs primarily through the medial femoral circumflex artery (MFCA) with additional perfusion of the epiphysis from the artery of ligamentum teres in the minority of immature hips 1,2. A more recent cadaveric study utilizing microcomputed tomography (microCT) of the capital femoral epiphysis (CFE) demonstrated preservation of perforating vascular channels at both the posterolateral location of the MFCA and the posteromedial location of the artery of ligamentum teres in the majority of hips, with prevalence of the ligamentum teres vascular channels increasing with age 3. However, this study was performed in processed cadaveric specimens and could not reveal whether there was active perfusion through these vascular channels.…”

Pediatric Femoral Head Osteonecrosis Secondary to Trauma, Sickle Cell Disease, and Corticosteroid Therapy

“…In contrast to skeletally mature patients whose vascular supply to the femoral head may pass across the metaphysis into the epiphysis, pediatric patients with an open proximal femoral physis rely on arterial supply from the medial femoral circumflex artery and the artery of the ligamentum teres. [34][35][36] As the medial femoral circumflex vessel becomes intracapsular as the lateral ascending branches, it is consequently at risk to injury through direct trauma at the time of injury, tension or kinking due to displacement of the fracture, compression due to intracapsular hematoma, or iatrogenic injury during treatment. Injury through any of these mechanisms can compromise vascular supply to the femoral head.…”