Hindfoot Alignment Change After Total Ankle Arthroplasty for Varus Osteoarthritis.

BACKGROUND

In patients with end-stage varus ankle osteoarthritis (OA), hindfoot varus malalignment resulting from the varus deformity of the ankle joint is common. Although total ankle arthroplasty (TAA) performed to correct varus deformity of the ankle joint has the effect of correcting hindfoot alignment, no reports to date have described how much hindfoot alignment correction can be achieved. The purpose of this study was to identify correlation between ankle deformity correction and hindfoot alignment change after performing TAA in patients with end-stage varus ankle OA.

METHODS

A total of 61 cases that underwent TAA for end-stage varus ankle OA and followed up for at least 1 year were enrolled for this study. Correlation between changes of tibial-ankle surface angle (TAS), talar tilt (TT), and tibiotalar surface angle (TTS) and changes of hindfoot alignment angle (HA), hindfoot alignment ratio (HR), and hindfoot alignment distance (HD) measured preoperatively and at postoperative year 1 was analyzed.

RESULTS

TAS, TT, and TTS changed from 83.9 ± 4.1 degrees, 5.8 ± 5.0 degrees, and 78.1 ± 5.9 degrees, respectively, before operation to 89.2 ± 2.1 degrees, 0.4 ± 0.5 degrees, and 88.7 ± 2.3 degrees, respectively, after operation. HA, HR, and HD also changed from -9.2 ± 4.6 degrees, 0.66 ± 0.18, and -11.2 ± 6.9 mm to -3.7 ± 4.1 degrees, 0.48 ± 0.14, and -5.0 ± 5.3 mm. All the changes were statistically significant ( .001, respectively). The regression slope of correlation was 0.390 ( = 0.654) between TTS and HA; 0.017 ( = 0.617) between TTS and HR; and 0.560 ( = 0.703) between TTS and HD.

CONCLUSION

In patients with end-stage varus ankle OA, changes of hindfoot alignment could be predicted based on degree of ankle deformity corrected with TAA.

LEVEL OF EVIDENCE

Level IV, case series.