Géza Pap1, Andreas Machner, Friedemann Awiszus. 1. Neuromuscular Research Group, Department of Orthopaedics, Otto-von-Guericke University, Leipziger Street 44, D-39120 Magdeburg, Germany. geza.pap@medizin.uni-magdeburg.de
Abstract
OBJECTIVE: Improvements of quadriceps motor deficits represent a major therapeutical target in knee osteoarthritis (OA). In the present study, we investigated changes in quadriceps function at different stages of osteoarthritic cartilage damage. METHODS: Measurements of quadriceps voluntary activation (VA) and maximum voluntary contraction (MVC) were performed by a twitch interpolation technique and the total muscular capacity (TMC) was calculated as the ratio of MVC and VA. We assessed 68 patients (56.7+/-9.5 years) with stage II and 154 patients (65.6+/-6.0 years) with stage IV chondropathy. As controls, we used 85 age related healthy subjects (58.1+/-8.7 years). RESULTS: While TMC was significantly lower in stage IV (90.6+/-43.7 Nm) than in stage II chondropathy (109.6+/-51.0) there were no differences in the MVCs between both groups. Quadriceps VA was even higher in stage IV (77.2+/-13.2%) than in stage II chondropathy (70.8+/-16.0%). In the controls, MVC, VA and TMC were significantly higher than in both OA groups. CONCLUSION: We assume that a decrease of TMC might occur within the course of OA and, in consequence, VA increases to maintain quadriceps MVC.
OBJECTIVE: Improvements of quadriceps motor deficits represent a major therapeutical target in knee osteoarthritis (OA). In the present study, we investigated changes in quadriceps function at different stages of osteoarthritic cartilage damage. METHODS: Measurements of quadriceps voluntary activation (VA) and maximum voluntary contraction (MVC) were performed by a twitch interpolation technique and the total muscular capacity (TMC) was calculated as the ratio of MVC and VA. We assessed 68 patients (56.7+/-9.5 years) with stage II and 154 patients (65.6+/-6.0 years) with stage IV chondropathy. As controls, we used 85 age related healthy subjects (58.1+/-8.7 years). RESULTS: While TMC was significantly lower in stage IV (90.6+/-43.7 Nm) than in stage II chondropathy (109.6+/-51.0) there were no differences in the MVCs between both groups. Quadriceps VA was even higher in stage IV (77.2+/-13.2%) than in stage II chondropathy (70.8+/-16.0%). In the controls, MVC, VA and TMC were significantly higher than in both OA groups. CONCLUSION: We assume that a decrease of TMC might occur within the course of OA and, in consequence, VA increases to maintain quadriceps MVC.
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