Medial malleolar osteotomy for the correction of tibiotalar varus deformity during total ankle arthroplasty: Results in 95 ankles

Abstract

Background: The importance of deformity correction before or during total ankle replacement (TAR) has been recognized for a long time. Our results of TAR, combined with medial malleolar lengthening osteotomy, for the reconstruction of osteoarthritic ankles with varus deformity are hereby reported.

Methods: All ankles in which a medial malleolar osteotomy was performed during implantation of an ankle prosthesis during the period 1998-2018 were filtered out of our database. Preoperative coronal talar alignment was evaluated by measuring the angle between the tibial shaft and talar dome on the weightbearing mortise ankle radiograph. Patient-reported outcomes were measured with the Foot and Ankle Outcome Score (FAOS) and the Foot and Ankle Ability Measure (FAAM). A Kaplan-Meier survival curve was constructed and the number of revisions per 100 observed component years was calculated for interprosthetic comparison.

Results: A total of 95 TARs were included, consisting of the Alpha Ankle Arthroplasty (n = 22); Buechel-Pappas (n = 14) and the Ceramic Coated Implant Evolution (n = 59) prostheses. The preoperative average talar angle in these ankles was 12.4 degrees varus. In 33% (31/95) corrective procedures, in addition to the medial malleolar osteotomy, were performed. A reoperation rate of 44% (42/95) was found, including 28 revisions (revision rate 29% (4% septic; 25% aseptic) at an average follow-up of 5.9 years, resulting in a survival of 0.69 for the total cohort at 10 years of follow-up. At an average follow-up of 6.6 years the average FAOS scores were: FAOS_symptoms 66, FAOS_pain 73, FAOS_function 78, FAOS_sport 45 and FAOS_{quality of life} 56 respectively. The FAAM_adl score averaged 64.

Conclusion: This is the largest cohort of TAR combined with medial malleolar osteotomy to date. A 29% revision rate at 5.9 years of average follow-up compares unfavorably with regular cohort studies and with most other results in varus-deformed ankles. Scores on the FAOS and FAAM are comparable to those obtained in regular cohorts with similar length of follow-up. TAR in varus-deformed ankles necessitating medial malleolar osteotomy has an even higher failure rate than regular TAR. Obtaining a stable prosthesis with a neutrally-aligned hindfoot at the end of the procedure is of paramount importance.

Level of evidence: IV.

Keywords: Ankle prosthesis; Malleolar osteotomy; Varus deformity.