Influence of Aging on Microvascular Supply of the Gluteus Medius Tendon

PURPOSE The purpose of this cadaveric study was to assess the relation between age and microvascular supply of 3 areas of the gluteus medius tendon using a previously validated CD31 immunohistochemistry staining technique. METHODS Twenty-four fresh-frozen gluteus medius specimens were obtained through a posterolateral approach to the hip. Specimens aged 18 years or older, of either sex, and of any race were considered for this study. The average age of donors was 47.3 years (range, 18-68 years). Each sample was divided into 3 portions: musculotendinous, tendinous, and tendon-bone junction. H&E staining was used for qualitative structural analysis, and then all samples underwent staining with CD31 immunohistochemistry for quantitative assessment of vessels per square millimeter. A comparison of the microvessel density between zones according to age was performed by an analysis of variance. To evaluate the relation between microvessel supply and age, a regression model with curvilinear estimation was used. The data were fitted to a quadratic model. RESULTS Vascular supply in transversal and longitudinal cuts regardless of the zone was, on average, 53.9 ± 32.1 vessels/mm2 and 51.1 ± 19.3 vessels/mm2, respectively. All the areas of the tendon showed a strength of relation (R) ranging from 0.41 to 0.76 between age and vascular supply. In addition, the proportion of vascular supply change explained by age (R2) was significant in most cases (ranging from 0.17 to 0.56, with P < .05). CONCLUSIONS There is a chronological relation between aging and microvascular supply of the gluteus medius tendon, in which an initial increase occurs from 18 years of age to 30 to 40 years of age, with a progressive decrease after 50 years of age. CLINICAL RELEVANCE The findings of our study may have implications for increased vulnerability of the gluteus medius tendon and decreased healing potential.