Structural design and multiphase biomechanical evaluation of a topology-optimized metal 3D-printed dual-compression plate for patellar fractures

Abstract

Patellar fractures, especially transverse and comminuted types, often present mechanical challenges that exceed the capabilities of conventional fixation constructs. This study develops a topology-optimized metal three-dimensional-printed dual-compression patellar plate designed to improve fragment stability while maintaining appropriate intraoperative rigidity. The plate design was first refined using an original anatomically assembled thin bone plate, which underwent finite element analysis and topology optimization to preserve primary load-bearing paths and reduce excessive stiffness. The optimized structure was subsequently fabricated using selective laser melting with Ti-6Al-4V and mechanically evaluated in accordance with American Society for Testing and Materials F382 standards. Static four-point bending tests demonstrated a proof load (P) of 257.31 ± 5.40 N and structural bending stiffness of 1.10 ± 0.01 N·m². Fatigue testing revealed runout at 15% P, while failure occurred at higher load levels (25% P & 30% P), revealing two distinct modes: plate fracture at topology-optimized transition zones and locking-screw shear failure. Static tensile testing revealed that dual-compression fixation significantly (p<0.05) enhanced load-bearing capacity compared with single-compression fixation for both C1 (712 N vs. 517.5 N) and C3 (253.75 N vs. 205.25 N) fracture models. Dynamic knee-extension testing demonstrated that dual compression markedly reduced medial–lateral fracture micromotion, decreasing C3 gaps from 0.348–0.534 mm to 0.078–0.107 mm without increasing quadriceps reaction force. Overall, the topology-optimized dual-compression patellar plate provides mechanically validated interfragmentary stability, effective micromotion control, and a well-defined fatigue performance envelope, supporting its potential as an advanced fixation solution for clinically challenging patellar fractures.  

Keywords

Biomechanics / Dynamic tests / Four-point bending / Patella / Three-dimensional printing

Funding

This study is supported in part by NSTC project 113-2622- E-A49 -027 and 114-2923-E-A49 -014 -MY2 Taiwan.

Conflict of Interest

No potential conflict of interest was reported by the author(s).

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