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(2) (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(2) 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.