Background/objectives: The current literature lacks objective criteria to correctly identify patients in need of a total knee replacement. Surgery indication can be challenging for orthopedic surgeons, which may lead to high levels of patient dissatisfaction. The objective of this study is to describe a complete set of functional characteristics to identify patients with end-stage knee osteoarthritis in need of a total knee replacement, correlating data from strength and performance tests with pain, function, and quality of life questionnaires.
Methods: This was a cross-sectional study evaluating patients with end-stage knee osteoarthritis in a waiting list for total knee replacement at a University Hospital. The patients responded to subjective self-reported questionnaires and performance-based functional tests. Anthropometric data were also collected. The main outcome measures were Western Ontario and McMaster Universities Index (WOMAC), visual analog scale (VAS), Short Form-36, knee range of motion, thigh perimeter measurement, maximum voluntary isometric contraction, and 6-min walk test.
Results: We analyzed 122 patients (89 female). The functional profile of patients with severe knee osteoarthritis awaiting total knee replacement was described. Quadriceps strength (extensor torque) had a negative correlation with WOMAC (r = -0.3102; p < 0.05), VAS (r = -0.3247; p < 0.05), and a positive correlation with SF-36 Functional Capacity subscale (r = 0.321; p < 0.05). Poorer performance in the 6 min walk test also correlated with worse scores in the WOMAC (r = -0.35; p < 0.05), VAS (r = -0.48; p < 0.05) and SF-36.
Conclusions: The present article established a functional profile of patients with severe knee osteoarthritis with indication for total knee replacement, which may help orthopedic surgeons in their decision process. We also identified quadriceps strength and a 6 min walk test as the two most important functional parameters that correlate with knee osteoarthritis severity.
Keywords: chronic pain; knee osteoarthritis; physical functional performance; quality of life; total knee arthroplasty.