Exploring Appropriate Positioning of the Spiral Blade in Treatment of Subtrochanteric Fractures of the Femur Using Proximal Femoral Nail Antirotation.

OBJECTIVES

Subtrochanteric fractures have anatomic characteristics distinct from intertrochanteric fractures that may affect the positioning of the spiral blade during surgical treatment. Tip-apex distance (TAD) and calcar-referenced tip-apex distance (Cal-TAD) were measured to determine if these measures are reliable indicators to assist in the accurate placement of intramedullary nails and minimize postoperative complications.

METHODS

For patients treated with proximal femoral nail antirotation (PFNA) internal fixation between 2016 and 2020, we analyzed the TAD, Cal-TAD, and postoperative complications. Fracture healing was assessed radiographically at 6-week intervals until union. The incidences of axial cut-off, cephalad cut-off, and non-union were also examined. Analysis of variance and Fisher's exact test were performed to evaluate differences in complications between the TAD and Cal-TAD groups.

RESULTS

Data from 104 patients (58 males, 46 females) with a mean age of 56.9 years were analyzed. Fracture healing was observed in 90 (86.5%) patients at an average time of 14.92 ± 1.81 weeks. The healing rate was significantly higher when the TAD and Cal-TAD were controlled within the 20-25 mm range (p < 0.05). Postoperative complications occurred in 14 (13.5%) cases [cephalad cut-off, n = 5 (4.8%); axial cut-off, n = 4 (3.8%); non-union, n = 5 (4.8%)]. Five (4.8%) complications occurred without internal fixation failure. The fracture healing time and incidence of complications differed among groups defined by TAD and Cal-TAD measurements, and were shortest and lowest, respectively, in the 20 mm < TAD/Cal-TAD < 25 mm group.

CONCLUSIONS

In our cohort, use of PFNA internal fixation for treatment of unstable femoral subtrochanteric fractures and placement of the spiral blade in the middle or lower 1/3 of the femoral neck did not increase the incidence of complications. Therefore, we propose that the TAD rule of 20-30 mm should not apply to subtrochanteric fractures, and TAD and Cal-TAD should be controlled within the range of 20-25 mm to reduce the incidence of complications.