Open AccessMorphologic changes in the vastus medialis muscle in patients with osteoarthritis of the knee
Author(s) -
Fink Bernd,
Egl Monika,
Singer Joachim,
Fuerst Martin,
Bubenheim Michael,
NeuenJacob Eva
Publication year - 2007
Publication title -
arthritis & rheumatism
Language(s) - English
Resource type - Journals
eISSN - 1529-0131
pISSN - 0004-3591
DOI - 10.1002/art.22960
Subject(s) - atrophy , medicine , vastus medialis , osteoarthritis , muscle atrophy , pathology , anatomy , electromyography , physical medicine and rehabilitation , alternative medicine
Objective To investigate the frequency of structural changes in the vastus medialis muscle in patients with osteoarthritis (OA) of the knee. Methods Specimens of vastus medialis muscle from 78 patients with end‐stage OA of the knee undergoing total joint arthroplasty were examined histopathologically. Morphologic changes were assessed in relation to clinical features that might have contributed to muscle injury. Results All muscle specimens exhibited atrophy of type 2 fibers. In 32% of the patients, atrophy of type 1 fibers was also noted. Fiber type grouping of type 1 fiber in 15% of the patients and type 2 fiber in 37%, indicating reinnervation, led to the diagnosis of neurogenic muscular atrophy in 32% of the patients; selective atrophy of type 2 fiber in 68% of the specimens was interpreted as possibly resulting from pain‐associated disuse. Signs of muscle degeneration and regeneration were found in 65% and 96% of the samples, respectively. Soft tissue changes indicating long‐term disease, such as calcification, fibrosis, and lipomatosis, were frequently observed (in 69%, 71%, and 94% of the patients, respectively). Statistical analysis of clinical and morphologic parameters revealed a significant association between degenerative muscle changes and the presence of a varus deviation of the leg axis. Conclusion Patients with OA of the knee frequently exhibit muscle changes, with probable multifactorial etiology. Selective atrophy of type 2 fibers might reflect pain‐related immobilization of a limb. Changes such as neurogenic muscular atrophy, muscle fiber degeneration, and regeneration might contribute as cofactors in the development or progression of OA.