Monday, June 13, 2011

Total Ankle Replacement in the Varus Ankle

Authors:  Shock, R., Christensen, J., Schuberth, J. (2011). 

Reviewed by:  James Johnston, DPM

This is a retrospective study of patients with more than 5º of ankle varus arthrosis who underwent total ankle replacement before October 2007.  Patient preoperative, immediate postoperative and most recent post operative weight bearing films were evaluated.  The degree of varus deformity was determined by measurement of the long axis of the tibia to a perpendicular axis of the talar dome on AP and mortise views.

A total of 26 patients with preoperative varus ankle deformity of greater than 5 degrees were reviewed in the study.  Patient ages ranged from 63.85 ± 9.33 years, with 7 females and 19 males.  The average follow up was 16.69 ± 7.26 months.  The average varus deformity was 18.3º ± 6.4º on the AP preoperative radiograph and 16.8º ±6.79º on the mortise projection.  The immediate postoperative radiographs were measured and showed correction of 19º on the AP and 17º on mortise projections.  All corrections where within 1º of postoperative films at follow up. There was a significant change in coronal plane correction of varus deformity on both AP and mortise views indicating either one can be used for preoperative planning.  The sequence of corrective maneuvers for varus deformity was:  Ancillary pedal procedures including but not limited to subtalar arthrodesis, ankle ligament reconstruction and talonavicular arthrodesis.  A standard incisional approach was used followed by a medial deltoid sleeve release, lateral gutter resection, talar deformity reduction, tibial-talar preparation, component insertion and lateral ligament placation.

At the time of review there has been no standard surgical approach to the varus ankle TAA in foot and ankle literature.  This article demonstrates a stepwise approach to management of the rearfoot deformity and presents a convincing although limited case review for the indication of TAR in the varus ankle.  The article points out that the varus ankle deformity frequently involves ligamentous imbalance with leads to a maladaptive joint.  Previous literature has provided us with the suggestion that moderate to severe (10 º to 20 º) coronal plane deformity of the tibiotalar complex may be a contraindication to TAA.  This article argues that with proper soft tissue balancing and the reestablishment of the plantigrade foot with a neutral ankle mortise, success can be found at least in the intermediate follow up.

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