The Effect of Body Mass Index on Short-Term Complications and Patient-Reported Outcomes in Patients with Surgically-Repaired Achilles Tendon

Abstract

Category:

Ankle; Other

Introduction/Purpose:

Obesity has shown to be associated with postoperative wound complications, infection, VTE, and wound dehiscence in patients undergoing surgical repair of the Achilles tendon1–3. Obesity is often defined as body mass index (BMI) greater than 30kg/m². The Center for Disease Control defines adult BMI ranges as follows: underweight ( < 18.5kg/m²), healthy (18.5 to 25 kg/m²), overweight (25 to 30kg/m²), Class I obesity (30 to 35 kg/m²), Class II obesity (35 to 40 kg/m²), Class III obesity (40 kg/m² and above)4. The purpose of this study is to compare the postoperative complications and FAAM-VAS scores between patients with surgically-repaired Achilles tendon according to their BMI ranges.

Methods:

Patients with mid-substance Achilles tendon rupture surgically repaired between 2016 and 2021 were identified. Chart notes were reviewed up to the 2-year postoperative period for wound complications and infection. Age, sex, Type II diabetes, rheumatoid arthritis, smoking status, and body mass index at the time of surgery were collected. Foot and Ankle Ability Measure and Visual Analog Pain Scales (FAAM-VAS) were collected preoperatively and at 6 months, 1 year, and 2 years postoperative time points. A total of 116 patients were identified and stratified into four groups based on their body mass index4: 18.5kg/m² - 25kg/m² (Group 1; n=24), 25kg/m² - 30kg/m² (Group 2; n=50), 30kg/m² - 35kg/m² (Group 3; n=20), and >35kg/m² (Group 4;n=22). Analysis of Variance Testing or Kruskal-Wallis Testing was used to calculate p-values for continuous data and Chi-Square testing was used to calculate p-values for categorical data. Pairwise testing was also conducted when appropriate.

Results:

The difference in rates of infection resulting in wound dehiscence or abscess drainage was not statistically significant across groups (p=0.362). No patient experienced re-rupture of the ipsilateral Achilles tendon. Group 4 patients reported the highest preoperative FAAM Overall, FAAM-ADL, and VAS scores. Their postoperative FAAM-Overall and FAAM-ADL scores were the lowest at all postoperative time points. Compared to patients in Group 2, patients in Group 4 demonstrated significantly less improvement in FAAM Overall score at 6 months (p= 0.029), 1-year (p=0.006), and 2-years (p=0.039) from surgery. The improvement in FAAM-ADL and VAS pain scores were not significantly different across BMI groups. However, the magnitude of improvement in FAAM-ADL was the lowest for patients in Group 4 at all postoperative time points.

Conclusion:

BMI was not significantly correlated with postoperative wound complication, infection, or re-rupture rates, but patients with BMI >35kg/m² reported significantly less improvement in FAAM Overall scores at the 6-month, 1-year, and 2-year postoperative periods compared to those with BMI between 25 and 30kg/m².