SLR - March 2018 - Michelle L. Winder

Comparison of the Outcome of Total Ankle Arthroplasty for Osteoarthritis with Moderate and Severe Varus Malalignment and That with Neutral Alignment

Reference: Joo, S.D. and Lee, K.B. Comparison of the Outcome of Total Ankle Arthroplasty for Osteoarthritis with Moderate and Severe Varus Malalignment and That with Neutral Alignment. Bone Joint J. 2017 Oct;99-B: 1335-42.

Scientific Literature Review

Reviewed By: Michelle L. Winder, DPM
Residency Program: Hennepin County Medical Center, Minneapolis, MN

Podiatric Relevance: Total ankle replacement (TAR) has become an increasingly common treatment for end-stage ankle arthritis with continued improvements in implant systems and surgical technique.  In addition to preserving greater anatomical movement, it has been suggested that TAR results in more pain relief and an overall better quality of life compared to ankle arthrodesis. Even so, satisfactory outcomes after TAR are dependent upon appropriate patient selection. It has been proposed that a greater degree of preoperative varus deformity leads to early failure, and some suggest that a severe varus deformity should be a contraindication to TAR. This topic remains controversial in the literature, and the significance of a severe varus deformity on TAR outcomes has not been fully determined. The purpose of this study is to compare radiographic and clinical outcomes of TAR for treatment of end-stage OA in patients with neutrally aligned ankles versus moderate and severe varus malalignment.

Methods: This is a level III retrospective cohort in which TAR was performed for treatment of symptomatic ankle OA between 2005 and 2013 by a single surgeon using a cementless, three-component HINTEGRA prosthesis. A total of 105 patients were divided into three groups based on a preoperative coronal tibiotalar angle of neutral (<5°), moderate (5° to 15°) or severe (>15°) varus. Patients were matched for age, gender, BMI and follow-up duration. Outcome measures include radiographic assessment of varus alignment at one, three, six and 12 months postoperatively, complication rates and clinical assessment of preoperative and final postoperative results after a mean follow-up of 51 months utilizing American Orthopedic Foot and Ankle Society (AOFAS) ankle-hindfoot score, visual analogue scale (VAS) for pain, Short Form (SF)-36 and sagittal plane ankle joint ROM.

Results: The mean tibiotalar angle of all three groups was within neutral alignment (<5° varus) postoperatively; however, the severe varus group retained significantly greater varus compared to the neutral group. Mean AOFAS, VAS, SF-36 and ROM all improved at final follow-up among the three groups. There was no significant difference in any of these clinical outcomes between the three groups postoperatively other than significantly less improvement in the SF-36 score of the severe varus group compared to the neutral group. Complication rates did not significantly differ between the groups.

Conclusions: Based on the results of this study, the authors conclude that similar radiographic and clinical outcomes can be achieved in TAR patients with a moderate or severe varus deformity as those with neutral alignment. The authors caution that care must be taken to address causes of varus malalignment by utilizing appropriate adjunctive procedures to achieve a neutral postoperative alignment. More soft tissue balancing procedures, such as a medial deltoid ligament release and Modified Broström, were necessary in the severe varus group compared to the neutral group. Overall, this study helps demonstrate that TAR can be recommended as a potential treatment option for symptomatic ankle OA regardless of the severity of varus deformity, as long as proper implant positioning can be achieved with adjunctive procedures.

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