[IMAGING STUDY ON DESIGN AND GEOMETRIC MATCH OF A NEW TYPE OF SHORT FEMORAL INTERTROCHANTERIC NAIL WITH ANTERIOR CURVATURE]

OBJECTIVE

To design a new type of short femoral intertrochanteric nail (FITN) with anterior curvature (19.5 cm in length and 120 cm in radius) and observe the geometric match with medullary cavity of the femur.

METHODS

Between November 2015 and June 2016, 25 geriatric patients with femoral intertrochanteric fractures were treated with the newly designed FITN. There were 7 males and 18 females with an average age of 82.3 years (range, 65-94 years). According to AO/OTA fracture classification, 3 cases were rated as A1.2, 2 cases as A1.3, 5 cases as A2.1, 8 cases as A2.2, and 7 cases as A2.3. The interval between injury and operation was 3.2 days (range, 2-7 days). Postoperatively, the nail entry point position (anterior, central, and posterior) on sagittal plane, the nail tip position (6-grade scale) and the nail tail level (3-grade scale) were measured using fluoroscopy and X-ray films to evaluate the geometric match of the nail with medullary cavity of the femur.

RESULTS

One patient with Parkinson disease died of asphyxia and pulmonary infection. The other 24 patients were followed up 1-8 months (mean, 4 months). Fracture union time was 6-10 weeks (mean, 8 weeks). The mean Parker-Palmer mobility score was 5.5 (range, 4-8). No patient had hip-thigh pain. The nail entry point was positioned anterior in 2 cases (8%), central in 18 cases (72%), and posterior in 5 cases (20%). The distal nail tip located at the central canal axis (grade 0) in 15 cases (60%), at anterior without contact with the anterior inner cortex (grade 1) in 8 cases (32%), at posterior (grade -1) in 1 case (4%), and at anterior with slight nail-tip impingement with the anterior cortex (grade 2) in 1 case (4%). The proximal nail tail level did not protrude out beyond the greater trochanter (grade 0) in 13 cases (52%), protruded out less than 5 mm (grade 1) in 9 cases (36%), and more than 5 mm (grade 2) in 3 cases (12%).

CONCLUSIONS

The newly designed FITN has a good geometric match with the femur medullary canal in Chinese population, which may reduce the nail related complications.