Anav Chopra

Background:  Distal femoral osteotomy (DFO) is a joint-preserving surgical procedure used to correct valgus knee deformity, particularly in younger, active patients.¹ Although effective in restoring mechanical alignment and redistributing joint loading, DFO is associated with notable complication rates, including nonunion, delayed union, and hardware-related issues.² These failures are largely driven by the mechanical environment at the osteotomy site, where fixation constructs determine interfragmentary strain and load transfer. Traditional fixation plates are designed with uniform stiffness, which can lead to stress shielding, asymmetric healing, and suppression of callus formation.³ Recent advances in additive manufacturing have enabled the development of stiffness-tunable fixation plates that allow region-specific modulation of mechanical properties to promote physiologic bone healing.

Methods:  A literature review was conducted using PubMed and Google Scholar. Search terms included: “distal femoral osteotomy,” “fixation stiffness,” “bone healing mechanobiology,” “stress shielding,” “3D printing,” “lattice structures,” and “topology optimization.” Studies were selected based on relevance to fixation biomechanics, interfragmentary strain, callus formation, and load distribution. Both clinical studies and biomechanical or computational analyses were included to provide understanding of how implant design influences healing outcomes.

Results:  Evidence demonstrates that fixation stiffness is a key determinant of bone healing. Rigid locking plate constructs have been associated with reduced callus formation, asymmetric bone healing, and incomplete consolidation due to stress shielding effects.^3,4 In contrast, dynamic fixation systems, such as far cortical locking, have shown increased callus volume, enhanced bone mineral density, and greater construct strength.⁴ Biomechanical studies further highlight the importance of hinge integrity and osteotomy geometry, with hinge fractures reducing rotational stability by up to 70%.⁵ Moreover, stiffness-tunable plates can achieve significant reductions in stiffness through lattice structures while maintaining mechanical integrity.⁶ Topology optimization and gradient stiffness designs have been shown to improve stress distribution, increase load transfer to bone, and promote a more favorable healing environment at the osteotomy site.⁷

Conclusions:  Stiffness-tunable fixation plates represent a promising approach to improving outcomes in DFO by optimizing the mechanical environment for bone healing. By allowing for controlled load sharing and region-specific stiffness modulation, these designs address key limitations of traditional, rigid fixation. While current evidence is primarily preclinical and computational, early findings suggest potential improvements in healing, stability, and overall clinical outcomes. Future research should focus on clinical validation, long-term outcomes, and integration with patient-specific surgical planning.

Work Cited

1. Diaz CC, Ophelie Z. Lavoie-Gagne, Knapik DM, Korrapati A, Chahla J, Forsythe B. Outcomes of distal femoral osteotomy for valgus malalignment: A systematic review and meta-analysis of closing wedge versus opening wedge techniques. Am J Sports Med. 2023;51(3):798–811. https://doi.org/10.1177/03635465211051740. doi: 10.1177/03635465211051740.
2. Apseloff NA, Taoufik T, Kaeding CC, Magnussen RA, Flanigan DC, van der List JP. Postoperative weightbearing timing after distal femur osteotomy is not associated with rates of union or complications: A systematic review and meta-analysis. Knee Surg Sports Traumatol Arthrosc. 2026;n/a. https://doi.org/10.1002/ksa.70340. doi: 10.1002/ksa.70340.
3. Röderer G, Gebhard F, Duerselen L, Ignatius A, Claes L. Delayed bone healing following high tibial osteotomy related to increased implant stiffness in locked plating. Injury. 2014;45(10):1648–1652. https://doi.org/10.1016/j.injury.2014.04.018. doi: 10.1016/j.injury.2014.04.018.
4. Bottlang M, Lesser M, Koerber J, et al. Far cortical locking can improve healing of fractures stabilized with locking plates. J Bone Joint Surg Am. 2010;92(7):1652–1660. doi: 10.2106/JBJS.I.01111.
5. Ferner F, Hammersdorfer N, Hembus J, et al. Hinge screw or no hinge stabilization provides decreased stability compared to hinge plate in a biomechanical evaluation of distal femoral derotational osteotomies. Knee Surg Sports Traumatol Arthrosc. 2024;32(8):2120–2128. https://doi.org/10.1002/ksa.12251. doi: 10.1002/ksa.12251.
6. Subasi O, Karaismailoglu B, Ashkani-Esfahani S, Lazoglu I. Investigation of lattice infill parameters for additively manufactured bone fracture plates to reduce stress shielding. Comput Biol Med. 2023;161:107062. https://www.sciencedirect.com/science/article/pii/S0010482523005279. doi: 10.1016/j.compbiomed.2023.107062.
7. Al-Tamimi AA, Quental C, Folgado J, Peach C, Bartolo P. Stress analysis in a bone fracture fixed with topology-optimised plates. Biomech Model Mechanobiol. 2020;19(2):693–699. doi: 10.1007/s10237-019-01240-3.