PINTRACE: a computer program for assessment of pin positions in routine radiographs of femoral neck fractures.

A new method for determination of pin positions in internally fixated femoral neck fractures is described. In AP and lateral radiographs of the hip, measurements are made of the cervicofemoral angles, the diameter of the femoral head and neck, and the distances from the central femoral neck axis to each pin. From these values the positions of the fixation pins in defined straight AP and lateral projections are determined by geometric calculations. A computer program in BASIC was developed to perform the calculations and to produce graphic displays of cross-sections of the femoral head and neck with the corrected pin positions indicated. For routine radiographic examinations with unknown inclination angles of the X-ray beams, the error of the method is less than 5% of the femoral head diameter. With conventional methods of determining pin positions the error can exceed 25% of the femoral head diameter.