Can surface landmarks help us identify the gibson interval during surgical hip dislocation: a study of 617 hips

The Gibson approach, used in hip-preserving surgery, is intermuscular and develops the space anteriorly to the gluteus maximus. Reliable anatomical landmarks for the development of this interval do not exist, but the interval is marked by perforating vessels (PV) of the inferior gluteal artery. The aim of this study was to provide reference values for the relationship between palpable anatomical landmarks on the femur/pelvis and the anterior border of the gluteus maximus using CT scans of the proximal femur.

Single center retrospective study of 617 hips who underwent a CT-scan of the pelvis/femur. We defined 5 anatomical markers on the pelvis and proximal femur and measured the distance of the anterior border of the gluteus maximus in relation to the marker, which was either anterior or posterior. The amount PV's and it's location relative to the innominate tubercle were measured in the coronal plane. For each landmark we compared these subgroups: male vs female, age < 40 vs ≥ 40, categorical age (< 20; 20-40; 40-60; > 60), and categorical femoral torsion (< 10°; 10°-25°; 25°-35°; > 35°).

Mean location of the parameters A-E was at - 8.1 cm, 1.1 cm, 1.8 cm, 1.3 cm and 0.4 cm. Parameters B, C, and D were more posterior in the age ≥ 40 group. Parameters A-E were significantly more posterior in the age > 60 group. Parameters A and E were significantly more anterior in females than in males. 50% of the PV are found between 5 and 9 cm proximal to the innominate tubercle. No statistically significant differences were noted in the location of any of the perforating vessels in the different subgroups.

The Gibson interval is located more anteriorly in female patients and patients under 40 years of age. It is located more posteriorly in patients over 60 years of age. In addition, the interval moves anteriorly with increasing femoral torsion, most notably in patients with very high femoral torsion (> 35°).