Quantitative anatomic characterisation of the pelvic brim to facilitate internal fixation through an anterior approach.

PURPOSE To define the centre of the hip joint and the bone stock around the hip joint from the supra-acetabular portion or pelvic brim so as to avoid penetration of guidewire into the hip joint when performing internal fixation using the anterior approach. METHODS A total of 42 cadavers were utilised. Measurements were completed before and after cutting the pelvis into 4 pieces. Before cutting the pelvis, the centre of the hip joint was measured on the pelvic brim. After cutting the pelvis, the bone stock around the hip joint was measured in each section. The pelvic brim and the anteroinferior iliac spine were utilised as guide points in the measurements, because these parameters could be determined during an anterior surgical procedure. RESULTS On the pelvic brim, the reflected centre of the hip joint centre was located approximately 3.2 mm anterior to the distal edge of the anteroinferior iliac spine. The mean minimum bone stock of the pelvic brim was 14.0 mm in the centre of the hip joint section. CONCLUSION This study described the anatomical reference points around the hip joint, and the ways in which they can be utilised to increase the safety of the anterior approach for internal fixation. It is important to define the centre of the hip joint from the supra-acetabular portion or pelvic brim, given that it is not visualised during surgery using an anterior approach.