The Effect of Positive Medial Cortical Support in Reduction of Pertrochanteric Fractures with Posteromedial Wall Defect Using a Dynamic Hip Screw

BACKGROUND: We evaluated the radiological and clinical results of reduction using a dynamic hip screw according to the grade of medial cortical support in patients with AO Foundation and Orthopaedic Trauma Association (AO/OTA) classification type 31-A2 pertrochanteric fractures. METHODS: We enrolled 100 patients with AO/OTA type 31-A2 fractures with displaced lesser trochanter fragments (length of the cortical area longer than 20 mm on the pelvis anteroposterior view). Patients with positive medial cortical support were assigned to group 1 (n = 28); neutral medial cortical support, group 2 (n = 42); and negative medial cortical support, group 3 (n = 30). Radiological evaluation was done by measuring the change in the femoral neck-shaft angle and sliding distance of the lag screw. Clinical outcomes of each group were compared by means of the walking ability score proposed by Ceder. RESULTS: Group 1 showed significantly less changes in the femoral neck-shaft angle and shorter sliding distance than groups 2 and 3. Group 2 showed significantly less changes in the femoral neck-shaft angle and shorter sliding distance than group 3. Group 1 showed significantly higher walking ability scores than group 3 (p = 0.00). The use of trochanter stabilizing plates or fixation using wires for posteromedial wall defect resulted in no significant changes in terms of the femoral neck-shaft angle or sliding distance. CONCLUSIONS: In the treatment of pertrochanteric fractures accompanied by posteromedial wall defect using a dynamic hip screw, reduction with negative cortical support should be avoided.