Biomechanical analysis of different fixation methods for Rorabeck II supracondylar femoral fractures after total knee arthroplasty

Daizhu Yuan; Zhanyu Wu; Shunen Xu; Xin Wu; Jianxiang Teng; Chuan Ye

doi:10.1016/j.knee.2022.12.002

Biomechanical analysis of different fixation methods for Rorabeck II supracondylar femoral fractures after total knee arthroplasty

Knee. 2023 Mar:41:204-213. doi: 10.1016/j.knee.2022.12.002. Epub 2023 Jan 30.

Authors

Daizhu Yuan¹, Zhanyu Wu², Shunen Xu², Xin Wu², Jianxiang Teng², Chuan Ye³

Affiliations

¹ Department of Orthopaedics, The Affiliated Hospital of Guizhou Medical University, Guiyang, China; Center for Tissue Engineering and Stem Cells, Guizhou Medical University, Guiyang, China; Sports Medicine, The Affiliated Hospital of Guizhou Medical University, Guiyang, China.
² Department of Orthopaedics, The Affiliated Hospital of Guizhou Medical University, Guiyang, China; Center for Tissue Engineering and Stem Cells, Guizhou Medical University, Guiyang, China.
³ Department of Orthopaedics, The Affiliated Hospital of Guizhou Medical University, Guiyang, China; Center for Tissue Engineering and Stem Cells, Guizhou Medical University, Guiyang, China. Electronic address: yechuanchina@hotmail.com.

PMID: 36724579
DOI: 10.1016/j.knee.2022.12.002

Abstract

Background: Locking plate (LP) and retrograde intramedullary nailing (RIMN) are widely used to fix Rorabeck II supracondylar femoral fractures after total knee arthroplasty (TKA). The biomechanical properties of the implant used for treatment influence its longevity. Therefore, we aimed to evaluate the biomechanical stability of different fixations using finite element analysis.

Methods: Seven finite element models (FEMs) were established, including LP groups (short LP, long LP, and double LP), RIMN groups (short RIMN and long RIMN), and mixed groups (long LP with short RIMN and long LP with long RIMN). The stress of the implants around the fracture area was calculated to evaluate the biomechanical stability under loads.

Results: Stress was mainly distributed around the fracture area in all models. The stress-shielding phenomenon was most evident in the short LP. The trend in maximum equivalent stress values of implants around the fracture area for the seven internal fixations was: short LP (324.63 MPa) > short RIMN (306.37 MPa) > long LP (275.06 MPa) > long RIMN (262.74 MPa) > double LP (203.19 MPa) > long LP with short RIMN (124.42 MPa) > long LP with long RIMN (112.41 MPa). We found that the double LP can better disperse the stress than a single LP, and a long LP with long RIMN can prevent stress concentration and make the stress distribution more uniform.

Conclusion: From the perspective of biomechanics, long LP with long RIMN can stabilize fractures and avoid stress concentration in Rorabeck II supracondylar femoral fractures after TKA.

Keywords: Biomechanics; Finite element analysis; Internal fixation methods; Supracondylar femoral fractures; Total knee arthroplasty.

MeSH terms

Arthroplasty, Replacement, Knee*
Biomechanical Phenomena
Bone Plates
Femoral Fractures* / etiology
Femoral Fractures* / surgery
Finite Element Analysis
Fracture Fixation, Internal / methods
Fracture Fixation, Intramedullary* / methods
Humans
Periprosthetic Fractures* / etiology
Periprosthetic Fractures* / surgery