SLR - August 2015 - Mark Sharobeem

The Impact of Obesity on the Outcome of Total Ankle Replacement

Reference: Bouchard M, Amit 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: Mark Sharobeem, DPM
Residency Program: Wyckoff Heights Medical Center

Podiatric Relevance: Obesity is the leading preventable cause of death worldwide, with increasing rates in adults and children. Authorities view it as one of the most serious public health problems of the 21st century. Obesity increases the likelihood of various diseases, but this study focuses on its relationship to osteoarthritis. It is postulated that obese patients have a higher incidence of infection and revisional surgery following ankle replacements, but functional improvement may be equivalent to that of normal-weight patients. Ankle replacements are becoming a more common procedure for patients with end stage ankle arthritis. Having a successful ankle joint replacement can allow for a more normal gait as compared with ankle fusion.  

Methods: Thirty-nine obese patients with a BMI >30 at a mean follow-up time of 3.76 years and forty-eight non-obese patients with a BMI of <30 at a mean follow-up time of 3.92 years after total ankle replacement. Outcome measure scores (AOS and SF-36) were collected preoperatively and at least two years postoperatively. Complication and revision data were collected retrospectively and statistical analyses were performed with Wilcoxon signed-rank tests, and Mann-Whitney U tests. Survival analysis was conducted with the Kaplan-Meier method.

Results: Ten of thirty-nine patients (26 percent) in the obese group were morbidly obese (BMI of >40). The mean body mass index was 36.28 ± 5.43 for the obese group and 25.84 ± 3.00 for the non-obese group. The obese group had significantly worse preoperative SF-36 Physical Component Summary scores (p = 0.01) than the non-obese group. Preoperatively to postoperatively, both groups (obese and non-obese) demonstrated significant improvements (p < 0.001) in AOS pain, AOS disability, and SF-36 Physical Component Summary scores. Changes in these scores were similar for both groups. The SF-36 Mental Component Summary scores did not change significantly (p = 0.30) in either group. There was no significant difference (p = 0.48) in the proportion of complications or revisions between the groups.

Conclusion: Obese patients had worse function and increased disability preoperatively. Total ankle replacement in both groups showed significant improvement in pain and disability scores. There was also no significant difference in complications. Therefore, total ankle replacement had similar results in obese and non-obese patients and is a dependable treatment option for end stage ankle arthritis in both groups. Since, total ankle replacements are becoming one of the preferred surgical treatments for end stage ankle arthritis, I believe that this article provides vital statistical information for the evaluation of the patient population which should be considered for this procedure. There is a great risk of end stage ankle arthritis in obese patients due to the increased load placed on the ankle joint. This article is helpful in determining whether there are greater risks of complications in total ankle replacements in obese patients versus non obese patients and shows that ankle replacement is a valid option in obese patients and should be considered as a surgical treatment regimen. 

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