Isokinetic assessment of ankle dorsiflexors and plantarflexors strength in patients with knee osteoarthritis

Purpose: To evaluate the ankle concentric dorsiflexors and plantarflexors’ strength in patients with knee osteoarthritis (OA). Methods: Forty subjects with knee OA were included in the study. The first group consisted of 20 subjects suffering from unilateral tibiofemoral knee OA, with mean age (57.60 ± 4.50 years), mean weight (88.95 ± 11.93 kg), and mean height (169.95 ± 5.84 cm). The second group consisted of 20 subjects with no prior history of knee pain or injury, forming a control group, with mean age (58.70 ± 5.15 years), mean weight (91.10 ± 10.23 kg), and mean height (171.25 ± 6.41 cm). Dorsiflexors and plantarflexors’ concentric peak torque was measured at angular velocities 60 and 120°/second by using an isokinetic dynamometer. Results: At angular velocity 60°/second, the peak torque of dorsiflexors and plantarflexors of the control group was significantly higher than that of the knee OA group (P = 0.001, 0.040, respectively). At angular velocity 120°/second, the peak torque of dorsiflexors and plantarflexors of the control group was significantly higher than in the knee OA group (P = 0.001, 0.010, respectively). At angular velocities 60 and 120°/second, the dorsiflexion/plantarflexion ratio of the knee OA group was significantly lower than of the control group (P = 0.003, 0.010, respectively). Conclusions: The knee OA group displayed weakness in ankle dorsiflexor and plantarflexor muscles and a decrease in the dorsiflexion/plantarflexion strength ratio. Clinicians should consider exercises to increase ankle dorsiflexor and plantarflexor muscles’ strength when developing rehabilitation programs for patients with knee OA.