Reasons of the guide pin eccentricity of helical blade during proximal femoral nail anti-rotation internal fixation for femoral intertrochanteric fractures_Chinese Journal of Reparative and Reconstructive Surgery

Authors：

 WANG Xin ¹ , ZHANG Yingqi ¹ , DU Shouchao ² , ZHANG Shimin ² , CHEN Kai ¹ , WANG Zhiyuan ¹ , YUAN Feng ¹ , CHENG Liming ¹

1. Department of Orthopedics, Tongji Hospital of Tongji University, Shanghai, 200065, P.R.China;
2. Department of Orthopedics, Yangpu Hospital of Tongji University, Shanghai, 200092, P.R.China;

Corresponding author：

WANG Xin, Email: wangxin1681@126.com

Keywords：

Femoral intertrochanteric fracture; intramedullary nail; eccentricity; helical blade

DOI：

10.7507/1002-1892.202101054

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Objective To analyze the reasons and the influence of internal fixation about the guide pin eccentricity of helical blade during proximal femoral nail anti-rotation (PFNA) internal fixation for femoral intertrochanteric fractures.Methods A retrospective analysis of the intraoperative imaging data of 175 patients with femoral intertrochanteric fractures, who underwent closed reduction and PFNA internal fixation between January 2018 and January 2020, was performed. There were 76 males and 99 females with an average age of 79.8 years (mean, 61-103 years). The internal between admission and operation was 12-141 hours (median, 32 hours). According to AO/Orthopaedic Trauma Association (AO/OTA) classification, the fractures were rated as type 31-A1 in 64 cases and type 31-A2 in 111 cases. In the intraoperative fluoroscopy image by C-arm X-ray machine, the caputcollum-diaphysis (CCD) was measured after closed reduction and internal fixation, respectively; the angles between the center line of the head nail hole and the axis of proximal nail and between the axis of guide pin and proximal nail were measured, and the difference between the two angles was evaluated; the quality of fracture reduction was evaluated according to the alignment of the medial cortex, anterior cortex of the head and neck bone block, and femoral shaft cortex; the position of the helical blade in the femoral head was evaluated according to the Cleveland method.Results The CCDs of proximal femur were (134.6±6.8)° after closed reduction and (134.9±4.3)° after internal fixation. There was no significant difference between pre- and post-internal fixation (t=0.432, P=0.766). The angles between the center line of the head nail hole and the axis of proximal nail and between the axis of guide pin and proximal nail were (125.4±2.44)° and (126.3±2.3)°, respectively, showing significant difference (t=2.809, P=0.044). The difference between the two angles was (0.8±2.2)°. The guide pin eccentricity of helical blade occurred in 47 cases. After tapping the helical blade along the eccentric guide pin, 10 cases had fracture reduction loss, and 5 cases had a poor position of the helical blade in the femoral head. Conclusion During PFNA internal fixation, a variety of reasons can lead to the eccentric position of the guide pin of helical blade, including unstable fracture, soft tissue inserted, severe osteoporosis, mismatched tool, and fluoroscopic imaging factors. It is possible that the fracture end would be displaced again and the helical blade position may be poor when knocking into the helical blade along the eccentric guide pin. During operation, it should be judged whether the direction of the guide pin needs to be adjusted according to the eccentric angle.

Citation： WANG Xin, ZHANG Yingqi, DU Shouchao, ZHANG Shimin, CHEN Kai, WANG Zhiyuan, YUAN Feng, CHENG Liming. Reasons of the guide pin eccentricity of helical blade during proximal femoral nail anti-rotation internal fixation for femoral intertrochanteric fractures. Chinese Journal of Reparative and Reconstructive Surgery, 2021, 35(8): 950-955. doi: 10.7507/1002-1892.202101054 Copy

1.	Chang SM, Hou ZY, Hu SJ, et al. Intertrochanteric femur fracture treatment in Asia: what we know and what the world can learn. Orthop Clin North Am, 2020, 51(2): 189-205.
2.	Yu X, Wang H, Duan X, et al. Intramedullary versus extramedullary internal fixation for unstable intertrochanteric fracture, a meta-analysis. Acta Orthop Traumatol Turc, 2018, 52(4): 299-307.
3.	Kumar CN, Srivastava MPK. Screw versus helical proximal femoral nail in the treatment of unstable trochanteric fractures in the elderly. J Clin Orthop Trauma, 2019, 10(4): 779-784.
4.	张世民, 余斌. AO/OTA-2018版股骨转子间骨折分类的解读与讨论. 中华创伤骨科杂志, 2018, 20(7): 583-587.
5.	Roberts KC, Brox WT, Jevsevar DS, et al. Management of hip fractures in the elderly. J Am Acad Orthop Surg, 2015, 23(2): 131-137.
6.	Chang SM, Zhang YQ, Du SC, et al. Anteromedial cortical support reduction in unstable pertrochanteric fractures: a comparison of intra-operative fluoroscopy and post-operative three dimensional computerised tomography reconstruction. Int Orthop, 2018, 42(1): 183-189.
7.	Lee CH, Su KC, Chen KH, et al. Impact of tip-apex distance and femoral head lag screw position on treatment outcomes of unstable intertrochanteric fractures using cephalomedullary nails. J Int Med Res, 2018, 46(6): 2128-2140.
8.	Lee PY, Lin KJ, Wei HW, et al. Biomechanical effect of different femoral neck blade position on the fixation of intertrochanteric fracture: a finite element analysis. Biomed Tech (Berl), 2016, 61(3): 331-336.
9.	O’Malley MJ, Kang KK, Azer E, et al. Wedge effect following intramedullary hip screw fixation of intertrochanteric proximal femur fracture. Arch Orthop Trauma Surg, 2015, 135(10): 1343-1347.

1. Chang SM, Hou ZY, Hu SJ, et al. Intertrochanteric femur fracture treatment in Asia: what we know and what the world can learn. Orthop Clin North Am, 2020, 51(2): 189-205.
2. Yu X, Wang H, Duan X, et al. Intramedullary versus extramedullary internal fixation for unstable intertrochanteric fracture, a meta-analysis. Acta Orthop Traumatol Turc, 2018, 52(4): 299-307.
3. Kumar CN, Srivastava MPK. Screw versus helical proximal femoral nail in the treatment of unstable trochanteric fractures in the elderly. J Clin Orthop Trauma, 2019, 10(4): 779-784.
4. 张世民, 余斌. AO/OTA-2018版股骨转子间骨折分类的解读与讨论. 中华创伤骨科杂志, 2018, 20(7): 583-587.
5. Roberts KC, Brox WT, Jevsevar DS, et al. Management of hip fractures in the elderly. J Am Acad Orthop Surg, 2015, 23(2): 131-137.
6. Chang SM, Zhang YQ, Du SC, et al. Anteromedial cortical support reduction in unstable pertrochanteric fractures: a comparison of intra-operative fluoroscopy and post-operative three dimensional computerised tomography reconstruction. Int Orthop, 2018, 42(1): 183-189.
7. Lee CH, Su KC, Chen KH, et al. Impact of tip-apex distance and femoral head lag screw position on treatment outcomes of unstable intertrochanteric fractures using cephalomedullary nails. J Int Med Res, 2018, 46(6): 2128-2140.
8. Lee PY, Lin KJ, Wei HW, et al. Biomechanical effect of different femoral neck blade position on the fixation of intertrochanteric fracture: a finite element analysis. Biomed Tech (Berl), 2016, 61(3): 331-336.
9. O’Malley MJ, Kang KK, Azer E, et al. Wedge effect following intramedullary hip screw fixation of intertrochanteric proximal femur fracture. Arch Orthop Trauma Surg, 2015, 135(10): 1343-1347.

Chinese Journal of Reparative and Reconstructive Surgery

Reasons of the guide pin eccentricity of helical blade during proximal femoral nail anti-rotation internal fixation for femoral intertrochanteric fractures

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