Protection from stress in bone and its effects. Experiments with stainless steel and plastic plates in dogs.
(41/716)
In a preliminary experiment the paired radii and femora of dogs were tested for bone mineral mass and mechanical properties including the load at break, the ultimate bending strength and the modulus of elasticity; symmetry was observed for most of the parameters determined. The influence of the elasticity of materials used for the internal splintage of bone and its relationship to bone remodeling were then investigated for stainless steel and plastic plates applied to the femora of dogs. A significant decrease in bone mineral mass per centimetre length of bone and in mechanical properties was demonstrated for the femora plated with steel, and microradiography showed that this was due to massive endosteal resorption. A model for determining the influence of protection from stress in bone is presented. (+info)
Principle and stability of locking plates.
(42/716)
A new internal Mini-Locking-System was tested compared with conventional 2.0 mm Miniplates. Standardised osteotomies in the angular region of 16 human cadaver mandibles were fixed with a 6-hole-plate at the oblique line. Osteosynthesis and stability of fixation was proofed in a three-dimensional in-vitro-model in which functional load was simulated. Comparison of the different osteosynthesis techniques showed that in the case of Miniplate fixation torsion and gapping of the bone fragments occurred following plate application and screw tightening when the plates were pressed onto the bone, so last incongruences between bone surface and plate were transferred to the mobile bone fragments resulting in more extended gaps and torsion. This was only observed to a much lesser extent with the Mini-Locking-System due to the fixation principle avoiding pressure to the bone. During functional loading the Mini-Locking-System showed also a significant higher stability in comparison to conventional Miniplates. Due to the fixation method imitating the principles of a fixateur the screws form together with the plate and the cortical bone a frame construction. Loading forces are transmitted without the need of plate friction directly from bone over the screws to the plate resulting in higher stability. (+info)
Operative treatment of mid-shaft clavicular non-union.
(43/716)
Between 1974 and 1999, we treated operatively 28 patients with a symptomatic mid-shaft clavicular non-union using AO osteosynthesis, including bone grafting. Nine patients had a wave-plate osteosynthesis and 19 a standard AO/ASIF osteosynthesis. The mean follow-up was 10 (2-25) years. All but one non-union showed full bony consolidation. Pre-operatively, brachialgia was present in 12 patients. Of these patients, six were treated using standard osteosynthesis technique and six by wave-plate osteosynthesis. Post-operatively, patients treated by wave-plate osteosynthesis had no brachialgia and also had a higher Constant score than those patients treated using standard AO/ASIF techniques. (+info)
Reaming bone grafting to treat tibial shaft aseptic nonunion after plating.
(44/716)
OBJECTIVE: To investigate the effects of using intramedullary reaming to provide cancellous bone graft, and reamed intramedullary nail stabilisation to provide fragment stability on treating tibial shaft aseptic nonunions after plating. METHODS: 31 consecutive patients with tibial shaft aseptic nonunions after plating were prospectively treated. Indications for this technique included a tibial shaft nonunion with an inserted plate, a fracture level fit for traditional or locked nail stabilisation, absence of suspected infection and segmental bony defect at the time, and shortening of less than 2 cm. The plate was removed and the marrow cavity was reamed as widely as possible. A stable unlocked or locked intramedullary nail was then inserted. No extra cancellous bone graft was supplemented. RESULTS: 28 patients were followed up for a median period of 2.2 years (range, 1.0-5.2 years). All patients achieved solid union. The median union period was 4.5 months (range, 3.0-7.5 months). There were no significant complications. CONCLUSION: When reamed intramedullary nails are used to treat tibial shaft aseptic nonunions after plating, supplemented cancellous bone grafting can be spared. Despite the technique being simplified, the success rate is high. We therefore recommend its wide use to treat all suitable cases. (+info)
Posterior olecranon plating: biomechanical and clinical evaluation of a new operative technique.
(45/716)
The purpose of this investigation was to compare the biomechanical analysis of a new plating technique for olecranon fractures to tension band wiring, and review early clinical results. Six matched pairs of cadaveric ulnae were used for the biomechanical analysis. A transverse osteotomy of the mid part of the olecranon was made. One ulna of each pair was stabilized using a tension band and the other with a posterior hook plate. The ulnae were mounted and loaded, and displacement at the osteotomy site recorded. Twenty patients treated with this new technique (14 fractures and 6 osteotomies) were reviewed at one year (range: 8 to 18 months) for infection, union rate, hardware related complaints. and removal. Statistical analysis showed significantly less displacement occurred at the osteotomy site in the plating group. Clinically, all patients had fracture union, and there were no hardware related problems. Posterior plating with this technique achieves greater stability compared to tension band wiring. Early clinical results indicate a low level of hardware related complications. (+info)
New innovations in craniomaxillofacial fixation: the 2.0 lock system.
(46/716)
Rigid internal fixation with plates and screws is now standard for the treatment of fractures, osteotomies and reconstruction of the craniomaxillofacial skeleton. The latest innovations are self-drilling, self-tapping screws and locking miniplates. These screws offer the prospect of less instrumentation and faster application. Preclinical testing has shown them to be substantially more retentive in cancellous bone, a significant advance in cancellous block bone grafting. Locking 2.0 miniplates utilize double threaded screws which both lock to the bone and the plate creating a mini-internal fixator. This results in a more rigid construct with less distortion of the fracture or osteotomy, screws which do not loosen and less interference with bone circulation since the plate is not pressed tightly against the bone. Locking miniplates are designed for midface application in the repair of fractures, osteotomies and defects. Three configurations in a variety of shapes and lengths are available for mandibular surgery. The thinner and medium varieties are useful in transoral plating of fractures utilizing the Champy technique. The heavier, longer variety are used in unilateral edentulous fractures in the symphysis and parasymphysis as well as an aid to tumor resection and reconstruction with both free and vascularized grafts. They are not designed to replace the heavier 2.4 locking reconstruction plates designed for complex fractures or extensive reconstructions. (+info)
Spontaneous mandibular fracture in a partially edentulous patient: case report.
(47/716)
This article describes the case of a 78-year-old patient whose mandibular fracture was treated with miniplate osteosynthesis. After initial treatment, panoramic radiography revealed a fracture of the miniplate, and at follow-up, a loosening of the replacement plate. For the dental practitioner, this clinical case highlights the importance of panoramic radiography and occlusal analysis and stabilization for diagnosis of mandibular fracture, evaluation of miniplate fracture and treatment, especially in the absence of trauma. (+info)
Osteoplastic repair of the atlas.
(48/716)
Fractures of the atlas constitute 4% to 12% of all bony injuries of the cervical spine; most are treated successfully by a cervical orthosis. Nonunion may be associated with neck or scalp pain on movement and is treated conventionally by some form of craniocervical fusion, which restricts head movement. The authors describe a case in which direct repair of the bony ring with a titanium plate and screws allowed bone healing, relieved the symptoms and maintained a full range of neck movements. The titanium plate interfered little with postoperative MR and CT imaging. (+info)