The Role of Muscle Architecture as a Determinant of Functional Performance in Women With Knee Osteoarthritis

The following measurements were performed in subjects with knee osteoarthritis and healthy subjects with similar age-BMI and then a comparison was made between the 2 groups.

Measurements Pain severity: The Visual Analogue Scale (VAS) was used to assess the severity of knee and foot pain during activity. The 10-cm horizontal line was defined as 0 "no pain" and 10 "very severe pain", and the patients were asked to indicate their knee and foot pain level by drawing a line. This line was then measured in centimeters on both the dominant and non-dominant side.

Static foot posture: The Foot Posture Index (FPI) was used to evaluate foot posture in a relaxed position while standing. The FPI is showed to be a valid and reliable tool in individuals with knee OA. The FPI consisted of six items: 1) palpation of the talar head, 2) assessment of the curvature of the supra and infra lateral malleolus, 3) evaluation of the frontal plane position of the calcaneus, 4) identification of any prominence in the region of the talonavicular joint, 5) examination of the congruence of the medial longitudinal arch, and 6) measurement of abduction/adduction of the forefoot on the rear foot. Each item was scored from -2 to +2, and the total score ranged from -12 to +12. A higher positive score indicated a more pronated foot. A score of ≥6 indicated a pronated foot type, while scores of 0-5 indicated a neutral foot type, and scores of ≤-1 indicated a supinated foot type. OA side and dominant side assessed. All data on static foot posture were collected by the physiotherapist who has 5 years of experience in foot assessment (X). To avoid bias, the physiotherapist performing the assessment did not know which group the individuals were in.

Muscle architecture: Ultrasound, which is a measurement method with validity and reliability in individuals with knee OA, was used to evaluate the knee and ankle muscles. A total of six muscles were evaluated, including three knee muscles and three ankle muscles: Rectus Femoris (RF), Vastus Medialis (VM), Vastus Lateralis (VL), Tibialis Anterior (TA), Peroneus Longus (PL) and Medial Gastrocnemius (MG). The muscle thickness, pennation angle, fascicle length and fat thickness of each muscle were evaluated using B-Mode ultrasonography (E-Saote MyLab X8 eXP Ultrasound System, Florence, Italy) and a linear array transducer (4-11.4 MHz). It has been mentioned that there is muscle weakness in the muscles around the knee in knee OA, and in line with the investigators' hypothesis, the investigators thought that there may be differences in the muscles around the foot in these patients, so the investigators preferred to evaluate these muscles. All data on muscle architecture were collected by the same rheumatologist who has 5 years of experience in ultrasound assessment.

The images of the RF, VM, VL, and TA muscles were obtained with participants in a supine position. For the MG and PL muscle images, participants were instructed to lie prone. To enhance reproducibility and minimize the risk of sampling a muscle obliquely, the transducer was oriented parallel to the muscle fascicles and perpendicular to the skin.