Quantity and Quality of the Lower Extremity Muscles in Women with Knee Osteoarthritis

The objective of the study described here was to compare lower extremity muscle quantity and quality between individuals with and those without knee osteoarthritis (OA). Twenty-one women with knee OA (mild, n = 8; severe, n = 13) and 23 healthy patients participated. Ultrasonography was used to measure muscle thickness (MT) and echo intensity (EI) of the rectus femoris, vastus intermedius, vastus lateralis, vastus medialis, biceps femoris, gluteus maximus, gluteus medius, gastrocnemius, soleus and tibialis anterior. MTs of the vastus medialis and vastus intermedius were smaller, and EIs of the vastus medialis, vastus intermedius, gluteus medius and tibialis anterior were larger, in the severe OA group compared than in the healthy group. Compared with the healthy group, the mild OA group had decreased MT and enhanced EI. Changes in quality and quantity occurring with knee OA progression differed among muscles. In the vastus medialis, change was observed from an earlier stage.