Knowing ankle kinematics helpsassessment of osteoarthritis treatment

In persons with tibiotalar osteoarthritis (OA), subtalar joint motion during the stance phase of gait in the sagittal, coronal, and transverse rotational planes tends to occur in a direction opposite to that in persons who have normal ankles, according to researchers in the department of orthopedic surgery at Massachusetts General Hospital in Boston. This phenomenon represents a breakdown in the normal motion coupling seen in healthy ankle joints.

Kozanek and associates¹ used MRI and dual fluoroscopic imaging techniques to measure kinematics of the ankle joint complex in 6 patients with unilateral post-traumatic tibiotalar OA in simulated weight-bearing positions and compared the data with those from a normal cohort in a previous study. From heel strike to midstance, the tibiotalar joint with OA demonstrated 2.2° ± 5.0° of dorsiflexion and the healthy joint plantar flexed 9.1° ± 5.3°. From midstance to toe off, the subtalar joint with OA dorsiflexed 3.3° ± 4.1° and the healthy joint plantar flexed 8.5° ± 2.9°. The subtalar joint in the group with OA rotated externally 1.2° ± 1.0° and everted 3.3° ± 6.1° from midstance to toe off; in the joint in the control group, there was 12.3° ± 8.3° of internal rotation and 10.7° ± 3.8° of eversion. The authors noted that knowledge of ankle kinematics of joints with OA may help in the assessment of the results of treatment interventions and in the design of prostheses.

References:

1. Kozanek M, Rubash HE, Li G, de Asla RJ. Effect of post-traumatic tibiotalar osteoarthritis on kinematics of the ankle joint complex. Foot Ankle Int. 2009;30:734-740.