Alignment of ankle and hindfoot in early stage ankle osteoarthritis.

BACKGROUND: Supramlleolar osteotomy has been recommended to correct varus deformity of the tibial plafond, however we have seen only a few ankles with significant deviation of alignment in early stage osteoarthritis, in which realignment treatments might be necessary to modify the course of the disease. Our hypothesis was that there are diverse radiographic features of the tibial plafond and hindfoot in varus ankle osteoarthritis.

MATERIALS AND METHODS: The study included 154 ankles of 98 patients with medial osteoarthritis, and 80 ankles of 80 normal subjects. On weightbearing AP radiographs, the tibial anterior surface angle (TAS), tibial axis-medial malleolus angle (TMM) and talar tilt angle was measured. On weightbearing lateral radiographs, tibial lateral surface angle (TLS) was measured. On the hindfoot alignment view, the heel alignment angle and heel alignment ratio were obtained. Inter- and intraobserver reliabilities were obtained for all radiographic parameters. The radiographic parameters were compared among the normal ankles and the ankles in different stages of ankle arthritis by the Takakura classification.

RESULTS: Inter- and intraobserver reliability were very high for all radiographic parameters except TLS. There was no statistically significant difference in TAS among stages 2, 3a, and 3b. TAS was 86.9 +/- 2.4 degrees, 86.2 +/- 3.3 degrees, and 85.4 +/- 4 3.1 degrees in stage 2, 3a, 3b, respectively. There was no significant difference in hindfoot alignment among normal, stage 2, stage 3a. The hindfoot alignment angle was 0.5 +/- 8.1 degrees, 0.5 +/- 6.8 degrees, and 9.6 +/- 9.1 degrees in Stage 2, 3a, 3b, respectively.

CONCLUSION: Alignment of the tibial plafond and hindfoot was variable in early stage ankle osteoarthritis.

LEVEL OF EVIDENCE: III, Retrospective Case Control Study