A biomechanical comparison of single- versus double-threaded cannulated screws for femoral neck fractures of Pauwels type Ⅲ
10.3760/cma.j.issn.1671-7600.2019.12.009
- VernacularTitle: 单头与双头螺纹空心钉固定治疗PauwelsⅢ型股骨颈骨折的生物力学性能比较
- Author:
Geng XIANG
1
;
Yafei FENG
;
Jiangang CHENG
;
Yang GAO
;
Xiaofan HU
;
Tiancheng MA
;
Guoxian PEI
;
Guolin MENG
Author Information
1. Department of Orthopaedics, Xijing Hospital, The Medical University of Air Forces, Xi’an 710032, China
- Publication Type:Journal Article
- Keywords:
Femoral neck fractures;
Fracture fixation, internal;
Bone nails;
Biomechanics;
Pauwels Ⅲ
- From:
Chinese Journal of Orthopaedic Trauma
2019;21(12):1064-1068
- CountryChina
- Language:Chinese
-
Abstract:
Objective:To compare the biomechanical performance between the single- versus double-threaded cannulated screws in the treatment of femoral neck fractures of Pauwels type Ⅲ.
Methods:Models of femoral neck fracture of Pauwels type Ⅲ (70°) were made of the Sawbone synthetic composite femurs. All specimens were divided into 2 groups (n=12). Group A was fixated with single-threaded cannulated screws and group B with double-threaded cannulated screws, both in an inverted triangle configuration. The screws ranged from 90 to 95 mm in length and from 7.3 to 7.5 mm in diameter. All the specimens were subjected to axial stiffness and failure load tests with 7° valgus (simulating normal two-legged weight-bearing stance) and 25° valgus (simulating normal one-legged weight-bearing stance) and torsion test as well. The 2 groups were compared in the torques at axial stiffness angles of 1°, 2°, 3°, 5° and 7°.
Results:Group B had significantly greater axial stiffness at 7° valgus and 25° valgus (89±26 N/mm and 128±37 N/mm) and failure load (1,154±368 N) than group A did (36±12 N/mm and 47±16 N/mm; 688±94 N) (P< 0.05). The torques increased with the increase in rotation angle in both groups. However, the torques in group B (3.26±0.96, 4.16±1.23, 4.64±1.13, 5.59±1.26 and 6.53±1.47 N·m) were all significantly larger than in group A (1.44±0.19, 2.03±0.41, 2.33±0.62, 2.74±0.87 and 3.05±1.07 N·m) (P<0.05).
Conclusion:Double-threaded cannulated screws may provide better biomechanical stability than single-threaded ones, due to their substantial improvement in anti-compression and anti-rotation performance.
