The stabilising effect by a novel cable cerclage configuration in long cephalomedullary nailing of subtrochanteric fractures with a posteromedial wedge

• Published in: Clinical biomechanics (Bristol) Vol. 68; pp. 1 - 7
• Main Authors: Mukherjee, Pavel, Brattgjerd, Jan Egil, Niratisairak, Sanyalak, Nilssen, Jan Rune, Strømsøe, Knut, Steen, Harald
• Format: Journal Article
• Language: English; Norwegian
• Published: England Elsevier Ltd 01.08.2019
• Subjects: Biomechanics; Cerclage cable; Composite bone; Intramedullary nail; Posteromedial buttress; Subtrochanteric fracture; Biomechanics; Intramedullary nail; Composite bone; Posteromedial buttress; Cerclage cable; Subtrochanteric fracture
• ISSN: 0268-0033; 1879-1271
• DOI: 10.1016/j.clinbiomech.2019.05.023

Clinical studies suggest that an adjunctive cerclage in intramedullary nailing of subtrochanteric fractures improves the outcome. Despite this, to what extent various cerclage configurations influences the fixation strength, remains undocumented. We tested the hypothesis that the stability of subtrochanteric fractures with a posteromedial wedge treated with long cephalomedullary nail varies with cerclage configuration. 40 composite femurs with a subtrochanteric osteotomy including a posteromedial-wedge were locked by cephalomedullary nailing (T2 recon, Stryker) and divided into 4 groups. In Group-A no cerclage was applied. The Group-B received a lateral tension-band (cerclage cable with crimp, Depuy-Synthes). Without any fixation, the wedge-component was removed in these groups. The Group-C was fixed with a cerclage encircling the wedge-component, while in the Group-D a novel figure-of-8 cerclage stabilised the wedge-component. Each femur was tested quasi-static in a material-testing-machine for stiffness calculation, first horizontally to simulate seated-position and then vertically to simulate standing-position. Finally, cyclic testing was performed in the upright-posture to measure deformation over time. In Group-D the mean stiffness in the sitting-position was 6.4, 5.8 and 3.1 times higher than the Groups-A, B and C, respectively, and correspondingly 2.0, 2.1 and 1.7 times higher in the standing-position (p < 0.05). Over time, Group-D demonstrated less mean deformation than tension-band (p = 0.05), while the deformation was not significantly different from the other groups. Additional use of cerclage enhances the stability of intramedullary nailed subtrochanteric fractures, and use of the figure-of-8 cerclage configuration, compressing the entire posteromedial-buttress, is the superior technique. •Subtrochanteric fractures are best treated operatively with long cephalomedullary nailing.•Varus-deformity during reduction should be avoided.•Stabilisation of posteromedial-buttress is recommended to avoid varus-deformity.•An adjunctive cerclage in intramedullary nailing of subtrochanteric fractures improves the outcome.•The novel figure-of-8 cerclage-technique is the superior method.