HISTOLOGICAL CHANGES OF THE LABRUM IN COXARTHROSIS

Abstract

Coxarthrosis is a common problem. Changes in all articular structures during coxarthrosis were described extensively, besides labrum. This study was designed to:

1. describe histological changes in the labrum during coxarthrosis, and correlate them with radiographic changes

2. compare changes in various portions of the labrum

3. assess labrum status in main etiological types of coxarthrosis.

Methods: Consecutive patients scheduled for THR were analyzed. Cases of systemic disorders, septic arthritis of the hip, previous hip surgeries were excluded. All hips were assessed radiographically, and staged according to Hip Osteoarthrosis Radiographic Grading System (HORGS) and for etiology to: dysplastic, idiopathic and avascular necrosis (AVN) groups. From the group of 90 patients in 77 hips we were able to harvest hip labrum during THR. All labra were examined by histological techniques for the presence of: labral matrix degeneration of, granular matrix breakdown, pseudocysts formation, matrix calcifications, chondrocyte apoptosis, macrophage and lymphocyte infiltration, vascular ephiteliar cell and blood vessel formation. After analysis labral histological degeneration score (LHDS) (0–11 points) was designed and computed.

Results: Degeneration of the labral matrix was found in all specimens, granular matrix breakdown in 98%, pseudocysts in 91%, calcifications in 22 %, apoptosis in 19%, macrophage infiltration in 30%, lymphocyte infiltration in 19 %, vascular ephiteliar cell in 39 % and blood vessel formation in 35 % of specimens. Average LHDS for all cases was 5.4, and was the highest (6.1) in dysplastic coxarthrosis, followed by idiopathic changes (LHDS 5.7). Significantly lower (p=0.02) values were found in AVN group (LDHS 3.7). In 35 randomly selected patients anterior, middle and posterior portion of labrum was evaluated separately. The highest LDHS was found in middle portion 5.9, comparing to anterior (LDHS 3.5) and posterior (LDHS 4.25) portion, and this difference was significant (p=0.002). Radiographic assessment showed that 10 % of patients had grade 1 changes according to HORGS, 28 % grade 2, and 62% grade 3 changes. Strong correlation (p=0.0002) was found between LDHS and radiographic HORGS scores. Labra of the patients with severe coxathrosis showed more degeneration changes.

Conclusions: Hip labrum shows various degenerative changes in the course of coxarthrosis like other structures in the joint. Degree of histological degeneration correlates well with radiographic changes. Small labral changes were found in AVN group with no destruction of acetabulum, the highest labral degeneration was found in cases of dysplastic coxarthrosis. The biggest changes were noted in the middle portion of the labrum. The results of this study proved that degeneration of the labrum is simultaneous with other articular structures and labral degeneration itself promotes coxarthrosis.