Postoperative range of motion trends following total ankle arthroplasty.

Background: It is still unknown how ankle range of motion changes following total ankle arthroplasty. This study was undertaken to more accurately address patient expectations, guide postoperative rehabilitation, and improve our understanding of how ankle range of motion changes with time.

Methods: 119 total ankle replacements of 3 different prosthetic designs from 1 surgeon were retrospectively examined and compared. Ankle dorsiflexion and plantar flexion ranges of motion were calculated and analyzed preoperatively and postoperatively at 6 weeks, 3 months, 6 months, and 1 year. The different ankle replacement systems were analyzed individually and together to determine whether trends were replicated.

Results: No significant increase in ankle range of motion was found 6 months postoperatively (P = .75). Mean combined postoperative range of motion did not change significantly from 24.3 degrees at 1 year versus a preoperative mean of 22.7 degrees (P = .75). Mean dorsiflexion improved significantly at the 6-week postoperative stage by 5.5 degrees (P < .001), whereas plantar flexion only improved by 2.9 degrees (P = .06). Mean dorsiflexion improved from preoperative levels by 5.4 degrees (P = .001), whereas mean plantar flexion decreased by 3.7 degrees (P = .004).

Conclusions: We found no notable improvement in ankle range of motion after 6 months following total ankle arthroplasty. We also found a disproportionately higher increase in dorsiflexion compared with plantar flexion following surgery and an overall reduction in mean plantar flexion range compared with preoperative values. Notwithstanding this discrepancy, total mean ankle range of motion 1 year postoperatively was similar to preoperative values. Reasons for the discrepancy between dorsiflexion and plantar flexion are unclear.

Level Of Evidence: Level III, retrospective comparative study.