Biomechanical analysis of the role of hinge support fixators on hinge stability in medial closing wedge distal femoral osteotomy

• Published in: Clinical biomechanics (Bristol) 2022-01, Vol.91, p.105528-105528, Article 105528
• Main Authors: Matsushita, Takehiko, Akiyama, Takenori, Osano, Kei, Yokoyama, Yasuharu, Okazaki, Ken
• Format: Article
• Language: English
• Subjects: Distal femoral osteotomy; Fixators; Hinge fracture; Support plate
• ISSN: 0268-0033; 1879-1271
• DOI: 10.1016/j.clinbiomech.2021.105528

This study aimed to examine the hinge-stabilizing biomechanical effects of hinge support fixators, applied for lateral hinge fractures sustained following distal femoral osteotomy. Medial closing wedge distal femoral osteotomy was performed using a locking plate on 10 cadaveric limbs. The limbs were divided into two groups: the non-fracture group and the lateral hinge fracture group. A cyclic axial load of 400 N was applied to the knee to keep it extended and flexed at 45°. The hinge-stabilizing effects of adding a screw or a short support plate to the lateral fracture site were examined by measuring the translation and rotational angles of the anterodistal and posterodistal hinge positions as well as the surface strains of the medial locking plate. Translation and rotation in the fracture group were significantly more pronounced than in the non-fracture group, at the anterodistal and posterodistal positions. Translations at both positions were significantly reduced, by adding the support plate, during both extension and 45-degree flexion in the fracture group. The rotation at the posterodistal position upon extension and the anterodistal position upon 45-degree flexion was significantly reduced by the support plate. The surface strain of the medial plate in the fracture group was significantly reduced by the support plate upon both extension and 45-degree flexion. Lateral hinge fractures caused abnormal hinge movements, which were significantly reduced by the short support plate. A short support plate could be used if a hinge fracture occurs during distal femoral osteotomy, to improve lateral hinge stability. •Hinge fracture in distal femoral osteotomy increased abnormal hinge movements.•The increased abnormal movements were reduced by the short support plate.•The hinge stability was not significantly improved by a hinge support screw.•The short support plate can be an option when a hinge fracture occurs.