Changes in gait following the Scandinavian Total Ankle Replacement.

BACKGROUND: There is a resurgence of popularity with regard to total ankle arthroplasty, although there are limited data documenting the effect of total ankle arthroplasty on ankle joint motion, gait, or ankle function. The purpose of this study was to perform a prospective evaluation of the effect of the Scandinavian Total Ankle Replacement on gait.

METHODS: We prospectively studied fifty consecutive patients with advanced ankle arthritis who underwent unilateral total ankle arthroplasty with the Scandinavian Total Ankle Replacement ankle prosthesis. Three-dimensional gait analysis was performed with use of a twelve-camera digital-motion capture system. Kinetic parameters were collected with use of two force plates. Temporal-spatial measurements included stride length and cadence. The kinematic parameters that were measured included the sagittal plane range of motion of the ankle, knee, and hip. The kinetic parameters that were studied included ankle plantar flexion-dorsiflexion moment and sagittal plane ankle power. The mean period of follow-up was forty-nine months (range, twenty-four to 108 months).

RESULTS: Temporal-spatial analysis showed that walking velocity increased as a function of increases in both cadence and stride length, and to significant levels for each. Kinematic analysis showed that ankle range of motion increased from a mean of 14.2° to 17.9° (p < 0.001), with the increase coming from increased plantar flexion. Increased motion was also measured at the hip and knee. Significant increases were found in ankle power (from 0.69 to 1.00 W/kg [p < 0.001]) and ankle plantar flexion moment (from 0.88 to 1.09 Nm/kg [p < 0.001]).

CONCLUSIONS: This study demonstrated that, at the time of intermediate-term follow-up and in comparison with the effects of ankle arthrodesis on gait as reported in previous studies, total ankle arthroplasty was associated with a more normal ankle function and a more normal gait, both kinetically and in terms of temporal-spatial parameters. More importantly, the study demonstrated marked improvement in multiple, objective parameters of gait following total ankle arthroplasty as compared with the patient's own preoperative function. The long-term maintenance of the gait improvements will require further study.