Vascularity of the hip labrum: a cadaveric investigation

Abstract

Purpose: The purpose of this study was to define the vascularity of the hip labrum and to identify regional differences in vascular penetration that may have implications for the healing potential of this structure.

Type of study: Injection study of human cadavers to investigate the vascularity of the hip labrum.

Methods: Twelve hips from 6 human frozen cadavers devoid of severe articular pathology were used. High-resolution surface-coil magnetic resonance imaging (MRI) was performed in both sagittal and coronal planes to better define anatomic planes in 2 dimensions and to correlate Spalteholz sections with the surrounding joint and labral anatomy. Each pelvis was injected with intra-arterial India Ink and frozen; 3-mm sagittal or coronal sections were then cut and processed using a modified Spalteholz technique, yielding anatomic zones of the labrum. Six specimens were cut in the sagittal plane and 6 were cut in the coronal plane. Specimens were examined at x10 magnification with transillumination. Anatomic zones with regional variations in vascularity were defined.

Results: The anterior and superior aspects of the labrum showed degenerative changes on MRI and under direct manual transillumination in 75% of specimens. Overall, there was a relatively poor vascular supply to the labrum; however, there were regional differences between anatomic zones. Zone I (capsular contribution) had significantly more vascularity than zone II (articular side) (P < .01). Zone IA (the portion of the zone not attached to bone) showed the most consistent source of vessels across all specimens (smallest variation between specimens); however, zone IB (the portion of the zone attached to bony acetabulum) had the greatest overall mean vascularity score. These differences were not statistically significant. Furthermore, vascularity patterns were not significantly different in the anterior, superior, posterior, and inferior labral regions, nor were they different in torn versus intact specimens.

Conclusions: The cadaveric specimens evaluated in this study had a relatively avascular hip labrum. However, the increased vascularity seen in zone I (capsular side) may have implications for treatment, similar to that described in the meniscus of the knee.

Clinical relevance: A better understanding of the vascularity of the hip labrum will guide treatment of labral pathology and may have implications for the healing potential of this structure. Labral tears occurring in the vascular zone may be amenable to arthroscopic repair rather than debridement.