Authors response: the lateral femoral wall

Dear Editor, We would like to thank the authors [1] for showing keen interest in our article [2] comparing two different implants for fixation of intertrochanteric fractures with a compromised lateral femoral wall. We have emphasised in our article that in spite of the general consensus about the importance of the lateral femoral wall in the management of intertrochanteric fractures, the literature is not clear about the exact area of the proximal femur which constituents the lateral femoral wall. Gotfried [3] defined it loosely as the proximal extension of the femoral shaft, but did not define its exact proximal or distal extent. Similarly, Palm et al. [4] defined it as the lateral femoral cortex distal to the vastus ridge without qualifying the distal extent. To clarify this confusion, we have defined both the proximal as well as the distal extent of the lateral femoral wall: (1) the proximal extent is the point on the lateral femoral cortex where the line drawn as a tangent to the superior femoral neck meets it (point b in Fig. 4. of the original paper [2]) and (2) the distal extent is the point on the lateral femoral cortex where the line drawn as a tangent to the inferior femoral neckmeets it (point d in Fig. 4. of the original paper [2]). The proximal extent defined by us, as rightly observed by the authors, is slightly above the vastus laterals ridge. This ensures two things: (1) all isolated fractures above it can be safely labelled as avulsion fractures of the greater trochanter and (2) all low intertrochanteric fractures, which exit lateral to the greater trochanter, near the vastus ridge and have a vulnerable lateral femoral wall, can be included. Similarly, taking the distal extent as defined by us ensures that (1) any fracture below it can be safely labelled as subtrochanteric fracture and (2) all reverse oblique (AO 31A 3.1–3.3) intertrochanteric fractures can be included (Fig. 1). If we were to define the lateral femoral wall as drawn by the authors [1], two large groups of intertrochanteric fractures, namely (1) low intertrochanteric fractures, which exit lateral to the greater trochanter near the vastus ridge, with a vulnerable lateral femoral wall, and (2) AO 31A 3.1–3.3 fractures with a preoperatively broken lateral femoral wall, would be excluded. We need to understand that a lateral femoral wall fracture which is seen on immediate postoperative intertrochanteric fracture radiographs fixed with DHS can be due to two reasons: (1) either the lateral femoral wall is broken pre-operatively, as is the case in AO 31A 3.1–3.3 fractures, or (2) the lateral femoral wall is vulnerable pre-operatively and breaks intra-operatively during the large diameter drilling for the sliding hip screw [3–6]. This is usually the case in AO 31A 2.2 and 31A 2.3