Femoral intertrochanteric nail (fitn): a new short version design with an anterior curvature and a geometric match study using post-operative radiographs

OBJECTIVE

Femoral intertrochanteric fractures are usually fixed with short, straight cephalomedullary nails. However, mismatches between the nail and the femur frequently occur, such as tip impingement and tail protrusion. The authors designed a new type of short femoral intertrochanteric nail (fitn) with an anterior curvature (length=19.5cm, r=120cm) and herein report the geometric match study for the first of 50 cases.

METHODS

A prospective case series of 50 geriatric patients suffering from unstable intertrochanteric fractures (AO/OTA 31 A2/3) were treated. There were 15 males and 35 females, with an average age of 82.3 years. Post-operatively, the nail entry point position in the sagittal greater trochanter (in three categories, anterior, central and posterior), the nail-tip position in the medullary canal (in 5-grade scale) and the nail-tail level to the greater trochanter (in 3-grade scale) were measured using X-ray films.

RESULTS

For the nail entry point measurement, 5 cases were anterior (10%), 38 cases were central (76%), and 7 cases were posterior (14%). For the distal nail-tip position, 32 cases (64%) were located along the central canal axis, 13 cases (26%) were located anteriorly but did not contact the anterior inner cortex, 2 cases (4%) showed less than one-third anterior cortex thickness contact, and 3 cases (6%) were located posteriorly with no contact. For the proximal nail-tail level, there were no protrusions over the greater trochanter in 15 cases (30%), protrusion of less than 5mm in 29 cases (58%), and protrusion of more than 5mm in 6 cases (12%). The fitness was very high, as 96% cases showed no tip-cortex contact, and 88% cases showed less than 5mm proximal tail protrusion.

CONCLUSION

The newly designed femoral intertrochanteric nail has a good geometric match with the femur medullary canal and the proximal length in the Chinese population.

[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.