Determinants of fracture type in the proximal femur:​ biomechanical study of fresh frozen cadavers and finite element models

Yano, Sei; Matsuura, Yusuke; Hagiwara, Shigeo; Nakamura, Junichi; Kawarai, Yuya; Suzuki, Takane; Kanno, Keijiro; Shoda, Jumpei; Tsurumi, Yousuke; Ohtori, Seiji

Affiliations

¹Department of Orthopaedics Surgery, Graduate School of Medicine, Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba 260-8670, Japan

²Department of Bioenvironmental Medicine, Graduate School of Medicine, Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba 260-8670, Japan

Abstract and keywords

Background: Proximal femur fractures are usually categorized as either a cervical or trochanteric fracture, but the relationship between fracture type and fall direction is not clear. By cadaveric mechanical testing and finite element analysis (FEA), the aims of this research were to verify the factors that define the proximal femur fracture type and to clarify the change in stress distribution based on fall direction.

Methods: From fresh frozen cadavers, we obtained 26 proximal femora including ten pairs of 20 femora. We conducted quasi-static compression tests in two fall patterns (lateral and posterolateral), and identified the fracture type. We then examined the relationship between fracture type and the following explanatory variables: age, sex, neck shaft angle, femoral neck length, bone mineral density (cervical and trochanteric), and fall direction. In addition, for the ten pairs of femurs, the effect of fall direction on fracture type was examined by comparing the left and right sides. In addition, we generated the proximal femur finite element (FE) models from computed tomography data to simulate and verify the change of external force in different fall directions.

Results: In mechanical tests, only fall direction was found to have a significant relationship with fracture type (p = 0.0227). The posterolateral fall group had a significantly higher incidence of trochanteric fractures than lateral fall group (p = 0.0325). According to FEA, the equivalent stress in the lateral fall was found to be more concentrated in the cervical area than in the posterolateral fall.

Conclusion: In proximal femur fractures, fall direction was significantly associated with fracture type; in particular, trochanteric fractures were more likely to occur following a posterolateral fall than a lateral fall.

Keywords: Proximal femur fracture; Fracture type; Fall direction; Finite element analysis; Equivalent stress

Links

DOI: 10.1016/j.bone.2022.116352

PubMed: 35181576

WoS: 000773553300006

History

Received: 2021-12-5

Revised: 2022-01-24

Accepted: 2022-02-4

Online: 2022-02-15

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