Fracture-healing is a specialized type of woundhealing response in which the regeneration of bone leads to a restoration of skeletal integrity. While the process of fracture-healing is usually considered to be biologically optimum. the healing of 5 to 10 pen cent of the estimated 5.6 million fractures occurring annually in the United States is delayed or impaired”. The cause of the impaired healing is often unknown. However, problems with operative and non-operative interventions. such as inadequate mobilization of the fracture, distraction of fracture fragments by fixation devices or traction, repeated manipulations or excessive early motion of a fracture, or excessive peniosteal stripping and damage to other soft tissues during operative exposure, intenfene with healing and may cause a delayed union or a non-union. A delayed union on a non-union may also occur if a fracture becomes contaminated at the time of the injury or after an operation or if an acceptable apposition of the fracture fragments on stable fixation is not achieved25. Moreover. specific pants of the skeleton, such as the neck of the talus. the neck of the femur, and the campal scaphoid5, are known to be at increased risk for impaired fracture-healing. and there may be problems related to peculiarities of the local blood supply or difficulties with the control of the mechanical strain environment at these sites. Thus. while most fractures heal without problems. there are several conditions unden which enhancement of the repair process would be of great benefit to ensure the rapid restoration of skeletal function. The ability of injured patients to return to the work force or to recreational activities early would not only have a substantial economic impact on society but would also improve the oven-all physical and mental well-being of the patients. In this article, I will review some of the better descnibed and more extensively tested methods that have been used to stimulate fracture-healing. I will also provide an introduction to certain new technologies that could improve the repair of fractures. The article is organized in two sections. The first section is a discussion

Enhancement of fracture-healing.

In one embodiment of the invention, an anterior fixation system (30) includes a plate (31a-31g) defining a plurality of screw holes (34), a number of screws (32) and a number of locking assemblies (33) for fixing the screws (32) to the plate (31a-31g) The system (30) includes two bone screws (32), a fixed angle screw (50) and a variable angle screw (60) Either the fixed or variable angled screws (50, 60) may be implanted with a single plate (31a-31g), and either type of screw (50, 60) may be placed into any of the screw holes (34) along the plate (31a-31g) The several screw holes (34) may be in various patterns (38, 39, 40, 41, 42, 43, 44) The invention further contemplates a locking assembly (33) to lock one or more bone screws (32) within a respective screw hole (34) In one embodiment, the locking assembly (33) includes a washer (90) overlapping one or more screw holes (34), and a locking screw (85) In another embodiment, a locking washer (120) includes cut-outs (128) corresponding to the screw recesses (105), along with a notch (110) and key (129) configuration

Anterior cervical plating system

Fifty patients with inadequate bone volume for implant placement were treated with mandibular bone grafts from the symphysis or ramus. The choice of donor site was determined by defect morphology and recipient site location. Although the harvest of bone was associated with low morbidity, the ramus donor site resulted in fewer complications. Implants were placed secondarily following a 4- to 6-month healing period. The onlay grafts exhibited minimal resorption and maintained their dense quality. The symphysis grafts were larger in overall volume, with a corticocancellous morphology. The ramus area provided essentially a cortical graft that was well suited for veneering ridge deficiencies; however, the surgical access in some cases was more difficult than in the anterior mandible.

https://coimplante.odo.br/Biblioteca/Enxertos/Comparison%20of%20Intraoral%20Donor%20Sites%20for%20Onlay%20Grafting%20-%20Craig%20Misch.pdf

Comparison of intraoral donor sites for onlay grafting prior to implant placement.

This invention is anatomically contoured anterior cervical plates (2) with bone ingrowth surfaces, providing for intersegmental compressive pre-loading, and a rigid and locked interface to all of the bone screws (30), with those engaging the vertebrae deployed in highly convergent pairs. 
Said plates comprising: a recess for retaining a locking element for locking bone screws in said bone screw receiving holes, said recess having a central longitudinal axis offset from a transverse line passing through the central longitudinal axes of said first and second bone screw receiving holes, and a locking element movably engageable in said recess, said locking element being movable from at least a first position to a second position when engaged to said plate, said locking element being configured so as to permit insertion of bone screws into each of said first and second bone screw receiving holes when said locking element is in said first position and is engaged to said plate.

Multilock anterior cervical plating system

A group of 15 partially edentulous patients who needed alveolar ridge augmentation for implant placement, were consecutively treated using a two-stage technique in an outpatient environment. A total of 18 alveolar segments were grafted. During the first operation bone blocks harvested from the mandibular ramus or symphysis were placed as lateral or vertical onlay grafts and fixed with titanium osteosynthesis screws after exposure of the deficient alveolar ridge. After 6 months of healing the flap was re-opened, the screws were removed and the implants placed. Twelve months after the first operation implant-supported fixed bridges could be provided to the patients. Mean lateral augmentation obtained at the time of bone grafting was 6.5±0.33 mm, that reduced during healing because of graft resorption to a mean of 5.0±0.23 mm. Mean vertical augmentation obtained in the 9 sites where it was needed was 3.4±0.66 mm at bone grafting and 2.2±0.66 mm at implant placement. Mean lateral and vertical augmentation decreased by 23.5% and 42%, respectively, during bone graft healing (before implant insertion). Mandibular sites showed a larger amount of bone graft resorption than maxillary sites. All the 40 implants placed were integrated at the abutment connection and after prosthetic loading (mean follow-up was 12 months). No major complications were recorded at donor or recipient sites. Soft tissue healing was uneventful, and pain and swelling were comparable to usual dentoalveolar procedures. A visible ecchymosis was present for 4 to 7 days when the bone was harvested from the mandibular symphysis. From a clinical point of view this procedure appears to be simple, safe and effective for treating localised alveolar ridge defects in partially edentulous patients.

Clinical results of alveolar ridge augmentation with mandibular block bone grafts in partially edentulous patients prior to implant placement

Difficulties arise in the prediction of maintenance of graft volume over time when bone grafts are used for facial contour reconstruction. We hypothesize that graft fixation will decrease movement and lead to decreased resorption. Fixed and nonfixed endochondral (rib) and membranous (skull) onlay bone grafts measuring 30 X 10 X 4 mm were grafted to the mandible bilaterally in 10 adult sheep. Fixation was achieved using the lag-screw technique. Volume measurements using caliper technique were made 20 weeks postoperatively. The volume of graft present at 20 weeks was significantly greater for the fixed bone grafts (p less than 0.001): fixed membranous, 85.9 percent; fixed endochondral, 76.2 percent; nonfixed membranous, 55 percent; and nonfixed endochondral, 16.6 percent. The results are explained using biomechanical theories related to the effects of strain. At present, it is suggested by this study that when onlay bone grafts are stabilized, improved results with respect to graft resorption can be expected.

Fixation effects on membranous and endochondral onlay bone-graft resorption.

This paper investigates the relationship between bone resorption, the process of bone revascularization, and graft fixation. Vital staining techniques and microangiography were used to study the extent of graft revascularization of fixed and nonfixed endochondral (rib) and membranous (skull) onlay b

Fixation effects on membranous and endochondral onlay bone graft revascularization and bone deposition.

The choice of an internal fixation system for maxillofacial surgery is made difficult because of lack of information with respect to functional load. This study attempted to clarify some of the controversy with respect to maxillofacial use of these implants. Maximal compressive force to torque values were measured in standardized bone thicknesses of 1, 2, 3, and 4 mm. The screws tested were pretapped AO 1.5-, 2.0-, 2.7-, and 3.5-mm rescue screws and self-tapping Luhr, Champy, and AO 1.5- and 2.0-mm screws. Ten measurements were made for each screw type/bone thickness combination using a piezoelectric washer and torque screwdriver. It was apparent that for 1- and 2-mm bone thicknesses the use of self-tapping screws resulted in the highest compression values. In 3- and 4-mm bone thicknesses, pretapped screws offered the highest compression values. As expected, self-tapping screws had the highest torque values on insertion owing to torque loss in cutting the screw threads. The 2.7-mm screw offered no advantage over the 2.0-mm screws in 1- and 2-mm bone thicknesses but resulted in higher compression values in 3- and 4-mm bone thicknesses.

Berton A. Rahn

Papers

Fixation effects on membranous and endochondral onlay bone-graft resorption.

Fixation effects on membranous and endochondral onlay bone graft revascularization and bone deposition.

Comparison of compression and torque measurements of self-tapping and pretapped screws.