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Joint Diseases and
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Original Article · Open access

Optimizing fixation in medial distal femur fractures: A biomechanical study

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Atahan Durgal

Department of Orthopedics and Traumatology, Ankara Bilkent City Hospital, Ankara, Türkiye

ORCID: 0000-0002-6980-6745

Enver Kilic

Department of Orthopedics and Traumatology, Ankara Bilkent City Hospital, Ankara, Türkiye

ORCID: 0000-0001-5475-8966

Elif Naz Perdeci

Department of Biomedical Engineering, TOBB University of Economics and Technology, Ankara, Türkiye

ORCID: 0009-0002-2857-448X

Fatma Kubra Erbay Elibol

Department of Biomedical Engineering, TOBB University of Economics and Technology, Ankara, Türkiye

ORCID: 0000-0002-4117-1098

Taner Karlidag

Department of Orthopedics and Traumatology, Gaziantep City Hospital, Gaziantep, Türkiye

ORCID: 0000-0003-4250-0444

Burak Kulakoglu

Department of Orthopedics and Traumatology, Antalya City Hospital, Antalya, Türkiye

ORCID: 0000-0002-5590-8484

Teyfik Demir

Department of Mechanical Engineering, TOBB University of Economics and Technology, Ankara, Türkiye

ORCID: 0000-0001-6352-8302

Olgun Bingol

Department of Orthopedics and Traumatology, Ankara Bilkent City Hospital, Ankara, Türkiye

ORCID: 0000-0003-1720-1709

Guzelali Ozdemir

Department of Orthopedics and Traumatology, Ankara Bilkent City Hospital, Ankara, Türkiye

ORCID: 0000-0003-4279-0955

Abstract

Objectives: This study aims to biomechanically compare four fixation methods to identify the most stable construct under axial loading conditions.

Material and methods: A standardized osteotomy model simulating AO/OTA 33-B2.1 fractures was created in 28 synthetic femurs. Four groups (n = 7 each) were tested: (1) three 6.5-mm cannulated screws, (2) the same with an additional centrally placed screw, (3) three screws plus a 3.5-mm buttress plate, and (4) three screws combined with a reversed anatomical proximal tibial locking plate. Constructs were subjected to cyclic and static axial loading. The prespecified primary endpoint was load at 2-mm displacement, with stiffness and maximum load to failure as secondary outcomes.

Results: Group 4 exhibited the highest stiffness (802 ± 70 N/mm), maximum load (2360 ± 389 N), and resistance to 2-mm displacement (1138 ± 87 N). Group 2, with a centrally placed fourth screw, showed significantly improved performance in terms of maximum load compared to the traditional three-screw construct. While Group 3 improved stiffness over screw-only constructs, it did not significantly outperform Group 2 in key load metrics. Group 2, with a centrally placed fourth screw, demonstrated comparable stability to the buttress plate and anatomical locking plate in selected metrics, but remained inferior to the locking plate construct.

Conclusion: Central placement of cannulated screws to the medial femoral condyle enhanced axial stability in this synthetic model and represented a minimally invasive alternative to buttress plating in selected metrics. The highest stability was achieved with the combined use of cannulated screws and a locking plate. These results are restricted to axial loading and the tested endpoints; thus, further biomechanical, cadaveric, and clinical studies are warranted before generalizing to early weight-bearing. Given the anatomical challenges of the medial condyle, the development of anatomically contoured locking plates specifically designed for this region remains an important future direction.

Declarations

Author Contributions

A.D.: Study design and main writer of the work; E.K.: Study design, material preparation and implantation; E.N.P.: Statistical analysis; F.K.E.E.: Biomechanical testing of materials, designed biomechanical protocols, interpretation of the data; T.K.: Data collection and statistical analysis; B.K.: Proof-reading, implantation of the materials; G.O.: Mentor of the work, proof-reading; O.B.: Study design, editing the manuscript; T.D.: Setup of the testing machine, guidance.

Conflict of Interest

The authors declared no conflicts of interest with respect to the authorship and/or publication of this article.

Financial Disclosure

The authors received no financial support for the research and/or authorship of this article.

Data Sharing Statement

The data that support the findings of this study are available from the corresponding author upon reasonable request.

AI Disclosure

The authors declare that artificial intelligence (AI) tools were not used, or were used solely for language editing, and had no role in data analysis, interpretation, or the formulation of conclusions. All scientific content, data interpretation, and conclusions are the sole responsibility of the authors. The authors further confirm that AI tools were not used to generate, fabricate, or ‘hallucinate’ references, and that all references have been carefully verified for accuracy.

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