The effect of different screw-rod design on the anti-rotational torque: a biomechanical comparison of three conventional screw-rod constructs

• Published in: BMC musculoskeletal disorders Vol. 18; no. 1; p. 322
• Main Authors: Huang, Zifang, Wang, Chongwen, Fan, Hengwei, Sui, Wenyuan, Li, Xueshi, Wang, Qifei, Yang, Junlin
• Format: Journal Article
• Language: English
• Published: England BioMed Central Ltd 28.07.2017; BioMed Central; BMC
• Subjects: Analysis; Anti-rotational torque; Biomechanics; Bone Screws - statistics & numerical data; Digital video recorders; Humans; Medical equipment; Musculoskeletal diseases; Orthopedic Procedures - instrumentation; Rod-screw construct; Scoliosis; Scoliosis - surgery; Surgery; Surgical outcomes; Torque; United States > US; Biomechanics; Rod-screw construct; Anti-rotational torque
• ISSN: 1471-2474; 1471-2474
• DOI: 10.1186/s12891-017-1683-1

Screw-rod constructs have been widely used to correct spinal deformities, but the effects of different screw-rod systems on anti-rotational torque have not been determined. This study aimed to analyze the biomechanical effect of different rod-screw constructs on anti-rotational torque. Three conventional spinal screw-rod systems (Legacy, RF-F-10 and USSII) were used to test the anti-rotational torque in the material test machine. ANOVA was performed to evaluate the anti-rotational capacity of different pedicle screws-rod constructs. The anti-rotational torque of Legacy group, RF-F-10 group and USSII group were 12.3 ± 1.9 Nm, 6.8 ± 0.4 Nm, and 3.9 ± 0.8 Nm, with a P value lower than 0.05. This results indicated that the Legacy screws-rod construct could provide a highest anti-rotation capacity, which is 68% and 210% greater than RF-F-10 screw-rod construct and USSII screw-rod respectively. The anti-rotational torque may be mainly affected by screw cap and groove design. Our result showed the anti-rotational torque are: Legacy system > RF-F-10 system > USSII system, suggesting that appropriate rod-screw constructs selection in surgery may be vital for anti-rotational torque improvement and preventing derotation correction loss.