A Comparative Study to Assess the Preoperative Thickness of Lateral Trochanteric Wall as a Predictor of Postoperative Lateral Wall Fracture in Intertrochanteric Fracture Treated by Dynamic Hip Screw

Abstract

The aim of this study was to assess the preoperative thickness lateral trochanteric wall as a predictor of postoperative lateral wall fracture in intertrochanteric fracture treated by dynamic hip screw fixation. A Radiograph based Comparative study involved 66 patients with intertrochanteric fracture treated by dynamic hip screw fixation. All patients had an intact lateral wall preoperatively and were AO/OTA 31 A1 and AO/OTA 31 A2 fractures. Mean age of the patients was 75 years. All patients were followed up with x-ray at 1 month and 6 months postoperatively. Age, gender, side of fracture, type of fracture as per AO/OTA classification, the pre-operative thickness of the lateral trochanteric wall, the tip-apex distance and the status of the trochanteric wall after 6 months from surgery were subjected to analysis. Radiographs were retrieved from the Picture Archive and Communication System and thickness of the lateral wall calculated. Measurements were corrected for magnification using the radiological magnification factor. Of the 66 patients, a fracture of the lateral wall occurred in 26 patients (39.39%). The lateral was intact in 40 patients (60.61%). The mean pre-operative thickness of the lateral wall of the 26 patients with a lateral wall fracture was 17.8 mm (SD-6.45) compared to 26.9 mm (SD-6.93) in 40 patients without a lateral wall fracture. The mean thickness of trochanteric wall in 39 patients with A1 fracture was 27.5 mm (SD=7.17) whereas the mean thickness in A2 type fracture (27 cases) was 17.3 mm (SD=4.88).74.07% of patients with A2 type fracture developed a fracture of the lateral wall whereas only 15.38% of A1 type fracture had a fracture of lateral wall after a six months follow-up. Factors like age at the time of operation, gender, side of fracture, tip-apex distance (if less than 25 mm) has no significant relation with development of post-operative lateral wall fracture. In summary, when the lateral wall thickness is less than 20.55 mm there is significantly high chance of lateral wall getting fractured if fixed with a DHS alone.