The Association of Body Mass Index and Achilles Tendon Rupture: A Retrospective Case-Control Study

Achilles tendon rupture (ATR) is a common injury with an estimated incidence of about 7 to 40 per 100,000 person-years. Identifying risk factors for ATR is an important step toward injury prevention. Modifiable factors, such as body mass index (BMI), are of particular interest because of the potential for intervention, and recent studies have shown mixed results for BMI as a risk factor for ATR. This case-control study aims to compare the BMI of patients diagnosed with a primary ATR to age and sex-matched controls diagnosed with an ankle sprain.

A retrospective chart review of 168 patients was performed, which included 56 patients with ATR age- and sex-matched with 112 ankle sprain controls. Demographics and BMI data were collected and compared across the 2 groups. Mann-Whitney U tests and Fisher exact tests were used to determine differences between groups. Multivariate logistic regression models were used to further analyze significant variables.

The mean BMI for ATR was 33.4 and ankle sprain was 31.9, which was not statistically significant (P = .162). When BMI was divided into subclasses, there were significantly fewer patients who sustained ATR compared to ankle sprain controls in the class 1 (BMI 18-25; P = .020). Participating in sports (P < .001) and African American race (P < .001) were the only other statistically significant risk factors. Multivariate logistic regression showed increased likelihood of ATR for patients who were African American (P = .006), participated in athletics (P < .001), and had a BMI higher than 25 (P = .018).

This study found that a BMI between 18 and 25 was associated with lower rates of ATR when compared to BMI classes greater than 25. Our data suggests that BMI may be an independent factor associated with ATR, even in patients engaging in sporting activity.

Level III, case-control study.