SLR - February 2016 - Anthony Romano

Title: The Impact of Obesity on the Outcome of Total Ankle Replacement

Reference: Bouchard M, Amin A, Pinsker E, Khan R, Deda E, Daniels TR. The Impact of Obesity on the Outcome of Total Ankle Replacement. J Bone Joint Surg Am. 2015 Jun 3;97(11): 904-10.

Scientific Literature Review

Reviewed By: Anthony Romano, DPM
Residency Program: Franciscan Foot & Ankle Institute, Federal Way, WA

Podiatric Relevance: Understanding the postoperative course, complications, and disability following total ankle replacement in obese patients is crucial for the foot and ankle surgeon facing a patient population with constantly increasing BMIs. Obesity is one factor that may discourage surgeons from recommending and performing total ankle replacement as previous studies have demonstrated that obese patients undergoing hip and knee replacement have had a more morbid postoperative course in terms of pain, function, and complications. This study serves to guide the foot and ankle surgeon as to whether or not to perform a total ankle replacement on an obese patient and whether the postoperative course will differ from that of patients undergoing the same procedure with a normal BMI.

Methods: A retrospective cohort study was performed comparing thirty-nine obese patients (Average BMI of 36.28 kg/m2) to forty-eight non-obese patients (Average BMI 25.84 kg/m2) undergoing total ankle replacement for end-stage ankle arthritis. Statistical analysis was used to evaluate and compare the two groups pre and post-operatively in terms of disability, complications, and pain.  

Results: There was no difference in preoperative AOS pain scores or postoperative AOS pain scores between the obese and non-obese groups. Both groups had significant improvement in AOS pain scores from preoperative to postoperative states (score change of 35.7 in the obese group and score change of 33.8 in the normal BMI group). Both groups demonstrated significant improvement in AOS disability scores following TAR. The mean preoperative SF-36 PCS score was significantly worse for the obese group. Postoperatively, these scores were similar for both groups, 39.2 for the obese group and 40.3 for the non-obese group. The mean SF-36 MCS scores of the obese and non-obese groups were similar both preoperatively and at the time of the latest follow-up. Eighty-two and one tenth percent of the obese patients in the study and 89.6 percent of the non-obese patients had good outcomes and did not experience any adverse events. The number of complications and revisions in each group was similar. The mean operation-free survival time was 4.5 years for the obese group and 4.6 years for the non-obese group.

Conclusions: Obese patients with end stage ankle arthritis had worse ankle function and greater disability preoperatively than patients with the same pathology that were not obese. Total ankle replacement improves disability and functionality similarly and significantly in both obese and non-obese patients. The complication profile for both groups following TAR was similar. When thinking about TAR as an option for end stage ankle arthritis in obese patients, the results will likely be similar to results in a non-obese patient.

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