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Optimizing fixation in medial distal femur fractures: A biomechanical study

Durgal A, Kilic E, Perdeci EN, Erbay Elibol FK, Karlidag T, Kulakoglu B, Demir T, Bingol O et al.

Joint diseases and related surgery, 2026

7 participants

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…

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