Validation of the Western Ontario and McMaster Universities Osteoarthritis Index in Patients Having Undergone Ankle Fracture Surgery

The Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) is a patient-reported outcome measure (PROM) that is widely used to evaluate the pain, stiffness, and physical function of patients with osteoarthritis of the hip and knee. Although the WOMAC has also been used for patients after foot and ankle surgery, it has not been validated for this purpose. A total of 130 patients with surgically treated ankle fractures completed the WOMAC, Visual Analogue Scale Foot and Ankle (VAS FA), Lower Extremity Functional Scale (LEFS), 15D Health-Related Quality-of-Life Questionnaire (15D), and Visual Analog Scale for General Health (VAS general health) after foot and ankle surgery. The structural validity of the WOMAC was assessed by using Cronbach's α, and convergent validity was tested between the WOMAC and reference outcome measures. Cronbach's α for the index score was 0.98 and 0.95, 0.86, and 0.98 for the Pain, Stiffness, and Physical Function subscales, respectively. The Spearman correlation coefficients were ‒0.84, ‒0.74, ‒0.58, and 0.55 for the VAS-FA, LEFS, 15D, and VAS general health, respectively. The relationships with the VAS-FA, LEFS, 15D, and VAS general health were strong. All relationships were statistically significant (p < .001). The WOMAC provides valid scores for assessing pain, stiffness, and physical function in patients having undergone ankle fracture surgery.