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Background: Dynamic Hip screw (DHS) is a common procedure undertaken following intertrochanteric fractures of the femur representing 67% of all surgically treated intertrochanteric fractures in 2023 in the United Kingdom. Tip Apex Distance (TAD) has been introduced by Baumgartner et al, in 1995 and has become the gold standard for DHS lag screw positioning in the femoral head to avoid cut-out and failure. Several techniques have been described for intraoperative TAD evaluation.

Methods and Aim: In this study, we introduce a useful modification to the originally described Baumgartner technique in order to optimise the TAD of the lag screw during the DHS surgery. We evaluate, describe, and provide intraoperative imaging and compare it with alternative techniques described in the literature.

Results: We describe a modified technique for the intraoperative measurement of the lag screw TAD by referencing to the standard threaded portion of the DHS guide wire which is 9 mm in length. After the guide wire central insertion close to the femur apex, the lag screw tip should cross the threaded part of the guide wire achieving a TAD less than 18 mm. To our knowledge, this is the first study to describe this technique with intraoperative imaging as well.

Conclusions: Authors recommend using this modification to the Baumgartner original guide wire technique to decrease the rate of DHS cut-out and failure. The technique is a simple and reliable intraoperative technique, not requiring a special digital system nor the presence of a non-scrubbed surgical assistant in theatre. It also avoids the possible inaccuracy when depending only on the surgeon’s eye.

Keywords: Dynamic hip screw; Tip apex distance; Measurement; Technique