Quantification of femoral neck exposure through a minimally invasive Smith-Petersen approach

OBJECTIVES: To quantify the area of osseous exposure and identify six anatomic landmarks using a direct anterior approach to the hip. METHODS: Ten fresh-frozen hemipelves were dissected using a minimally invasive Smith-Petersen approach. Upon completion of the exposure, a calibrated digital image was taken from the surgeon's perspective. Identification of six osseous landmarks (anterior-superior acetabulum, anterior-inferior acetabulum, greater trochanter, lesser trochanter, anterior inferior iliac spine, and vastus ridge) was attempted either by direct visualization or palpation with a tonsil clamp. These landmarks exceed the border for any intracapsular hip fracture. The digital images were then analyzed using a computer software program, ImageJ (National Institutes of Health, Bethesda, MD), to calculate the square area of proximal femur exposed. RESULTS: The average square area of proximal femur exposed was 20.31 cm (standard deviation: 3.09, range: 15.16-24.18). The area exposed correlated with the original height of the cadaver (r = 0.69, P < 0.05). With the numbers available, there was no correlation between exposure and weight (P = 0.71) or body mass index (P = 0.87). In all 10 cadaver specimens, the 6 osseous landmarks were easily identified, 5 by direct visualization and 1 by palpation (lesser trochanter, deep portion) because of incomplete visualization. CONCLUSIONS: The minimally invasive Smith-Petersen approach to the hip allows for a wide exposure of the femoral neck averaging 20.31 cm and identification of six bony critical landmarks of the hip. It may be used for open reduction of subcapital, mid-cervical, and basicervical femoral neck fractures.