How reliable is the soft tissue radiological knee index in predicting superficial surgical site infection following total knee arthroplasty?

INTRODUCTION: The purpose of this study was to evaluate the association between the Soft Tissue Radiological Knee (SToRK) Index and the risk of developing a superficial surgical site infection (SSSI) following primary total knee arthroplasty (TKA).

METHODS: The SToRK Index was measured using calibrated long leg radiographs (LLR) in 174 patients undergoing TKA.

RESULTS: A moderate correlation was found between the SToRK Index and body mass index (BMI) (rs =0.574; p < 0.001). The SToRK Index was a better predictor of SSSI in females than males. In females, a SToRK Index cutoff of 2.01 had a sensitivity and specificity of 41.3% and 74.6% for developing SSSI, respectively, with a positive likelihood ratio of 1.63.

CONCLUSION: The SToRK Index can be used as an additional tool in assessing the risk for SSSI after TKA. It might be more predictive in females due to the different fat distribution compared to males.