Department of Orthopaedics, Shanghai Jiaotong University Affiliated Sixth People's Hospital, Shanghai, 200233, People's Republic of China.
National Key Laboratory for Manufacturing Systems Engineering, Xian Jiaotong University, Xi'an, 710054, Shanxi Province, People's Republic of China.
J Orthop Surg Res. 2023 Nov 28;18(1):902. doi: 10.1186/s13018-023-04244-z.
Calcaneal Sanders type II or III fractures are highly disabling with significant burden. Surgical treatment modalities include open reduction and internal fixation (ORIF) techniques and a variety of minimally invasive surgical (MIS) approaches. ORIF techniques are associated with complications and traditional MIS techniques need extensive intraoperative fluoroscopic procedures. The present study aims to investigate the effects of three different minimally invasive internal fixation (MIIF) techniques used to treat Sanders type II intra-articular calcaneal fractures using finite element analyses.
A 64-row spiral computed tomography scan was used to observe the calcaneus of a healthy adult. The scanning data were imported into Mimics in a DICOM format. Using a new model of a Sanders type II-B intra-articular calcaneal fracture, three minimally invasive techniques were simulated. Technique A involved fixation using an isolated minimally invasive locking plate; Technique B used a minimally invasive locking plate with one medial support screw; and Technique C simulated a screw fixation technique using four 4.0-mm screws. After simulating a 640-N load on the subtalar facet, the maximum displacement and von Mises stress of fragments and implants were recorded to evaluate the biomechanical stability of different fixation techniques using finite element analyses.
After stress loading, the maximum displacements of the fragments and implants were located at the sustentaculum tali and the tip of sustentaculum tali screw, respectively, in the three techniques; however, among the three techniques, Technique B had better results for displacement of both. The maximum von Mises stress on the fragments was < 56 Mpa, and stress on the implants using the three techniques was less than the yield strength, with Technique C having the least stress.
All three techniques were successful in providing a stable fixation for Sanders type II intra-articular calcaneal fractures, while the minimally invasive calcaneal locking plate with medial support screw fixation approach exhibited greater stability, leading to improved enhancement for the facet fragment; however, screw fixation dispersed the stress more effectively than the other two techniques.
跟骨 Sanders Ⅱ型或Ⅲ型骨折具有高度致残性，且负担沉重。手术治疗方法包括切开复位内固定（ORIF）技术和多种微创外科（MIS）方法。ORIF 技术与并发症相关，而传统的 MIS 技术需要广泛的术中透视程序。本研究旨在通过有限元分析研究三种不同微创内固定（MIIF）技术治疗 Sanders Ⅱ型关节内跟骨骨折的效果。
使用 64 排螺旋 CT 扫描观察健康成年人的跟骨。将扫描数据以 DICOM 格式导入 Mimics。通过建立新的 Sanders Ⅱ-B 型关节内跟骨骨折模型，模拟三种微创技术。技术 A 采用单独的微创锁定板固定；技术 B 采用微创锁定板加 1 枚内侧支撑螺钉；技术 C 模拟采用 4.0mm 螺钉的 4 点固定技术。在距下关节面施加 640N 的负荷后，记录骨折块和植入物的最大位移和 von Mises 应力，以通过有限元分析评估不同固定技术的生物力学稳定性。
在应力加载后，三种技术的骨折块和植入物的最大位移均位于跟骨支撑突和跟骨支撑突螺钉尖端；然而，在三种技术中，技术 B 对两种位移的效果均更好。骨折块的最大 von Mises 应力<56Mpa，三种技术的植入物的应力均小于屈服强度，其中技术 C 的应力最小。
三种技术均成功地为 Sanders Ⅱ型关节内跟骨骨折提供了稳定的固定，而带内侧支撑螺钉的微创跟骨锁定板固定方法具有更好的稳定性，从而改善了关节面骨折块的增强效果；然而，螺钉固定比其他两种技术更有效地分散了应力。
