• tendinosis;
  • extracellular matrix;
  • collagen

Ten patients, age 60 (48–75 years), with osteoarthritis (OA) of the hip and 10 patients, age 82.5 (60–90 years), with fracture of the collum femoris (FCF; minimum Garden stage III) underwent an open biopsy procedure from the internal obturator tendon in conjunction with a total hip replacement. The histological evaluation revealed that all tendon samples in the OA group revealed scar tissue; the corresponding was found in 50% of patients in the FCF group (P=0.02). There were also more GAGs (P=0.023) and calcium deposits (P=0.001) in the samples from the OA group. The ultrastructural evaluation revealed fewer small and medium-sized fibrils (P=0.001) and more non-collagenous extracellular matrix (ECM) (P=0.003) in the OA group. Taken together, the samples from the internal obturator tendon in the OA group revealed a more degenerative appearance with more scar tissue, change in fibril diameter distribution and more non-collagenous ECM. Our findings suggest that OA and periarticular tendinopathy are closely linked. Further research is needed to determine whether musculotendinous changes in the deep rotators are sequelae of joint pathology, or a contributing factor in the development of degenerative joint change.