Morphology and fixation pitfalls of a highly unstable intertrochanteric fracture variant.

PURPOSE To describe a variant of intertrochanteric fracture not well-characterised in the existing classification systems. METHODS 10 women and 2 men aged 59 to 98 (median, 80) years with intertrochanteric fractures characterised by a low intertrochanteric fracture, a basicervical fracture fragment, and a thin or fractured lateral wall with greater trochanteric comminution were reviewed. RESULTS The 12 fractures were classified as A2.1 (n=1), A2.2 (n=7), A2.3 (n=1), and A3 (n=3) according to the AO/OTA classification, and as type 3 (n=2), type 5 (n=7), and type 6 (n=3) according to the Evans classification. The fractures were characterised by greater trochanter comminution and a coronal plane fracture extending into the greater trochanter resulting in a loss of superolateral support. Patients were treated with the Proximal Femoral Nail Antirotation (n=5), the Proximal Femur Locking Plate (n=6), or the reversed Less Invasive Stabilization System for distal femur (n=1). Within the mean follow-up period of 6 months, 3 patients with plating and one patient with nailing had mechanical failure defined as loss of alignment of >10º or screw cutout. CONCLUSION This intertrochanteric fracture variant is highly unstable with a high failure rate. Loss of superolateral support rather than the medial calcar buttress is the main contributing factor to mechanical failure. Computed tomography is important in preoperative planning. Intramedullary nailing is more appropriate than extramedullary plating for such unstable fractures.