Sarcopenia is Associated with Nonunion of Open Tibia and Ankle Fractures

Abstract

Background: Sarcopenia is a clinical syndrome of diminished muscle mass and function associated with disability, poor surgical outcomes, and mortality. Open fractures of the tibia and ankle have a high risk for complications including nonunion and surgical site infection (SSI). The purpose of this study is to determine if sarcopenia is associated with SSI and nonunion in individuals that sustain open fractures of the tibia and ankle.

Methods: 111 consecutive adults who underwent operative fixation of open fractures of the tibia or ankle from 2006-2017 with preoperative CT of the abdomen and pelvis were retrospectively identified at a single institution. Eleven patients were lost to follow-up. The psoas index (PI = (RPA+LPA)/ height² (cm²/m²)) was calculated from bilateral psoas cross sectional areas measured on axial CT scans at the L3 pedicle. Patients were stratified by the presence of sarcopenia as defined by established gender specific PI cut-offs of <3.85 cm²/m² (women) and <5.45 cm²/m² (men). Records were also abstracted for comorbidities to determine a Charlson Comorbidity Index (CCI) score and postoperative complications including fracture nonunion and SSI. Logistic regression was used to model the relationships between complications, sarcopenia and other factors.

Results: 16/100 (16%) patients met gender specific criteria for the diagnosis of sarcopenia by PI. There was no difference in gender, age, or burden of medical comorbidity according to CCI between the sarcopenic and non-sarcopenic groups (all p>0.05). Nonunion occurred in 6 patients with sarcopenia (38%) and 12 without sarcopenia (18%) (Relative risk=2.42, 95%C!=1.08-5.43, p=0.0314). No association was found between sarcopenia and SSI, BMI, smoking status, ISS, and Gustilo and Anderson (GA) classification of open fracture (all p>0.2). GA classification was strongly associated with infection, with each successive classification having a nearly 3-fold increase in risk (p=0.0217).

Conclusion: Sarcopenia is an independent risk factor for fracture nonunion following operative fixation of open tibia or ankle fracture, but is not predictive of surgical site infection. Gustilo Anderson classification is strongly associated with SSI risk. Psoas index is a straightforward and objective method of identifying sarcopenia in patients with open fractures. Diagnosing sarcopenia in these individuals can inform medical decision making and patient counseling regarding risk for nonunion. Further work is needed to identify effective interventions to improve outcomes in these patients.Level of Evidence: III.

Keywords: malnutrition; non-union; open fractures; psoas index; sarcopenia.