PubMed · 9400648
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M Misra, M Dujovny, G Gonzales-Portillo, C Abood. 1997. Cranial titanium osteosynthesis systems.. https://doi.org/10.1016/s0090-3019(97)00336-4
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STUDY DESIGN: A retrospective analysis of graft and plate complications after multilevel anterior cervical corpectomy and fusion (ACF) attributed to spondylosis, stenosis, and ossification of posterior longitudinal ligament was conducted. OBJECTIVE: To identify factors contributing to graft and plate complications in this population. SUMMARY OF BACKGROUND DATA: Biomechanical factors contributing to the increased morbidity associated with plated multilevel ACF were evaluated. METHODS: Graft- and/or plate-related complications were retrospectively reviewed in 33 patients undergoing two-level ACF reconstructions and in seven patients having three-level ACF reconstructions performed with iliac crest grafting and instrumentation with a fixed-plated design (cervical spine locking plate). Neurologic status was assessed before surgery and after surgery using both the Nurick Grading Scale and modified JOA (Japanese Orthopaedic Association) Score. The patients were observed an average of 31.4 months after surgery. The follow-up included lateral flexion and extension radiographs and a neurologic examination. RESULTS: Two of the 33 patients undergoing two-level fusions available for long-term follow-up after surgery developed reconstruction failures. All of the remaining fusions were successful, demonstrated by lateral flexion and extension radiographs. Seven patients had plated three-level corpectomy reconstructions. Five of the seven who had anterior-only reconstruction failed. DISCUSSION: A two-level ACF reconstruction is reliable with an anterior strut graft and fixed screw plate construct. A three-level ACF reconstruction is not reliably achieved with an anterior-only construct. The construct failures may be attributed in part to the fixed-plated design being used, as well as the long lever arm of the construct. CONCLUSION: There is a 6% failure rate after fixed-plated (cervical spine locking plate) two-level ACF reconstruction but a 71% failure rate after three-level fixed-plated ACF reconstruction. Future consideration should be given to simultaneous posterior fusion.
Conventional plating has been performed since the nineteenth century, and since then Lambotte, Danis, and others have developed new plate designs to restore fractured bones. At the early stage of plating, mechanical aspects were the focus, and the biology of the bone was sometimes neglected. During the 1980s the AO/ASIF group started to work on new plate designs to minimize the disadvantages of plating with respect to cortical perfusion. To overcome the negative effect of compression forces on the periosteum, a new generation of plates, or internal fixators, were created. The key to these internal fixators is the locking mechanism of the screw in the implant, which provides angular stability. This technical detail ensures that compression forces on the bone surface are not necessary to gain stability of the bone-implant construct, which improves fracture healing and provides an excellent holding force even in osteoporotic bone. The locking mechanism also makes the technique of percutaneous plating easier because, in contrast to conventional plates, the fragments are not pulled toward the implant by the locking screws. The new internal fixator systems [LISS (less invasive stabilization system) and LCP (locking compression plates)] offer new approaches to trauma surgery, especially for metaphyseal fractures.
A three-dimensional finite element model of a fractured human mandible treated with plating technique was developed to simulate and to study the biomechanical loads and the stress field distribution. Biomechanical properties of bone have been thoroughly investigated experimentally. In this work, using the finite element method, complete clinical conditions (after surgical reduction, post-operatory period, complete healing period) were simulated. The mandible fracture was located in the symphysis region and one or two titanium miniplates, fixed with monocortical screws, were evaluated. The behaviour of a reduced human mandible with screwed miniplates, as well as its complete healing, is investigated and described.