Thickness of the Subcutaneous Fat as a Risk Factor for Surgical Site Infection following Fragility Hip Fracture Surgery

Introduction:
Surgical site infection (SSI) following fragility hip fracture (FHF) surgery is associated with increased morbidity and mortality. Prediction of patients at risk is fundamental.

Aim:
To determine whether subcutaneous radiographic fat measurement (SRM) is associated with increased risk for SSI.

Methods:
A retrospective case-control study was performed to compare SRMs at 3 locations around the hip. Patients diagnosed with SSI in the first post-operative year were matched with age, gender, surgical year, Charlsons` co-morbidity index score and surgical type controls, not diagnosed with SSI, at a 1:2 ratio. The diagnosis and type of SSI was based on accepted centers for disease control criteria. Measurements included the distance between (1) the sourcil to skin surface (SS), (2) the tip of the greater trochanter to skin surface (TGTS), and (3) the most prominent lateral aspect of the greater trochanter to skin surface.

Results:
45 patients with a diagnosis of SSI were compared with 90 controls. Infections occurred 27.4 (±24.8) days following surgery. SRM significantly differed between groups, and all were higher in the study group; SS 86.8±25.5 cm vs. 74.2±15.3 cm, TGTS 59.8±26.3 cm vs. 47.0±15.8 cm and LGTS 45.4±25.1 cm vs. 33.2±15.1 cm (p.= 0.003, 0.004 and 0.004 respectably). Intraclass correlation coefficients (intra-rater) were high for all three measurements (0.999 for all). Intraclass correlation coefficients (inter-rater) for SS, TGTS and LGTS were high, 0.749 (0.663-0.815), 0.792 (0.719-0.847) and 0.817 (0.751-0.866) respectively.

Conclusions:
SRMs were found to be a valid and reproducible tool for predicting high risk of SSI in geriatric patients sustaining a FHFs.