Dome Supramalleolar Osteotomies for the Treatment of Ankle Pain with Opposing Coronal Plane Deformities Between Ankle and the Lower Limb.

BACKGROUND

The dome-type osteotomy is a powerful technique for deformity correction of the limb. However, there is limited information about the utility of dome supramalleolar osteotomy (SMO) in ankle joint preservation surgery. This study aimed to describe the technique and indications for dome SMO in distal tibial malalignment.

METHODS

Twenty-three patients (23 ankles) who underwent dome SMO with a 2-year follow-up were reviewed. Dome SMO was indicated when there were opposing deformities in the ankle and lower limb mechanical axis (ie, varus ankle deformity with valgus lower limb alignment and vice versa) where inherent translation following conventional wedge-type osteotomies could worsen the deformity of the entire lower limb. Patients were divided into 2 groups based on preoperative ankle alignment: the varus ankle group (n = 11) and the valgus ankle group (n = 12). The radiographic correction was assessed using 6 parameters from weightbearing ankle and hindfoot alignment views. In addition, the lower limb mechanical axis was assessed with ankle center deviation (ACD) from the hip-knee (HK) line on the whole limb radiograph, and the weightbearing line (WBL) point was measured to identify changes in the weightbearing load within the ankle joint.

RESULTS

Preoperatively, the varus ankle group had varus ankle deformity (tibiotalar angle [TTA], 76.5 ± 5.8 degrees) with valgus lower limb mechanical axis, whereas the valgus ankle group had valgus ankle deformity (TTA, 99.1 ± 4.5 degrees) with varus lower limb mechanical axis alignment. Postoperatively, a significant improvement in the ankle alignment and the lower limb mechanical axis was observed in both groups. The ACD significantly changed toward the HK line, suggesting an improved lower limb mechanical axis, and the WBL point showed a significant shift of the weightbearing axis toward the uninvolved area within the ankle joint.

CONCLUSION

Dome SMO demonstrated a successful correction of local deformity while simultaneously realigning the hip-knee-ankle axis toward neutral. Additionally, an effective load shifting toward an uninvolved area within the ankle joint was observed.

LEVEL OF EVIDENCE: Level IV, case series.