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PubMed2001

[Analysis and experimental study of reasons for breakage in the bone fracture plate during internal fixation].

Bone fracture plate has been in clinical use for internal fixation of fracture, however, during healing, the steel plate breaks occasionally. This paper applied the static strength theory to imitate the pressed down combination out of shape that was borne by single limb of human body standing. Fracture was made on low limbs of the fresh dead body, fixed with a bone fracture plate. Strain measure was made on a bone fracture plate. Additionally, fatigue experiment and four-point bending experiment were carried out on a bone fracture plate. The reason for a breakage in the bone fracture plate was analyzed with static strength theory and low period fatigue theory.

Bone Plates↗
PubMed1994

Long-term follow-up of forearm bone diaphyseal plating.

A retrospective review of 175 patients treated with forearm bone plating for acute diaphyseal fractures, nonunions, and malunions was undertaken to identify problems related to plate removal as opposed to plate retention. One hundred thirteen patients retained their forearm plates, of which five patients experienced complications related to the plate, including infection, bone failure, plate failure, and loosening. Patients retaining forearm bone plates reported minimal discomfort or functional limitation. Sixty-two patients had plate removal at an average of 19 months after insertion. Ten patients suffered major complication, including seven refractures through screw holes, osteotomy, or original fracture sites. Fractures occurred at an average of six months after plate removal. The difference in complication rates between patients treated with plate removal and patients retaining plates was statistically significant.

Acute Disease↗
PubMed1999

The use of titanium plates for bone regeneration with root form implants: a case report.

In reconstruction of the partially and totally edentulous ridges that have bony defects due to old trauma or longstanding atrophy, it is necessary to reconstruct both the width and height of the alveolar ridge. This clinical case report covers bone regeneration prior to implant placement to achieve an aesthetic and functional base for prosthetic restoration. The focus of this report will be on bone regeneration, which does not depend on the utilization of a barrier membrane.

Adult↗
PubMed2002

Biologic tendon fixation to metallic implant augmented with autogenous cancellous bone graft and bone marrow in a canine model.

Soft tissue attachment to a metallic prosthesis is required for the improvement of the functional outcome of endoprosthetic reconstructions. Direct tendon attachment to the metallic surface can be achieved through fibrous ingrowth, but such an attachment has a mechanical strength less than one fifth of that of a normal tendon insertion. Regeneration of a transitional structure between the tendon and the metallic surface similar to the normal morphology of a direct tendon insertion may improve the mechanical strength of the new tendon insertion. The objective of the study was to investigate the effect of placement of an interpositional autogenous cancellous bone plate augmented with bone marrow on the mechanical strength of the soft tissue attachment to the metallic surface. The insertion of the supraspinatus tendon was reattached to a porous titanium prosthesis in a canine shoulder model. An autogenous cancellous bone plate supplemented with bone marrow was positioned between the metallic surface and the tendon. Assessment of load-bearing, as a measure of functional recovery, and radiological analysis were performed at 3, 6, 9, 12, and 15 weeks. The animals were euthanized 16 weeks after surgery, and the specimens were subjected to tensile mechanical testing (six animals) and microradiographic-histologic evaluation (three animals). Functional analysis showed a 90.3% recovery of preoperative weight-bearing by 16 weeks (p < 0.05). The mineralized area around the prostheses increased by 63% over time (p < 0.05). Tensile stiffness and strength of the reconstruction were 43.6% and 42.8% of the intact tendon insertion values, respectively. These results were higher than in previous experiments using the direct tendon attachment (p < 0.01, p < 0.05, respectively) or the interpositional bone plate without marrow supplementation (p < 0.05, p < 0.05, respectively). Morphologically, the tendon reattachment site contained the basic tissue transition zones in normal tendon insertion to bone. Inductive bone grafting, supplemented with bone marrow, in the biologic augmentation of tendon anchoring onto a porous metallic prosthesis was an effective technique to increase the mechanical strength of the tendon attachment to the metallic prosthesis.

Animals↗
PubMed1995

Rapid orthopedic lengthening of the mandible in primates by sagittal split osteotomy and distraction osteogenesis: a pilot study.

This study proposes the development of an intraoral surgical approach to distraction osteogenesis to treat maxillofacial defects. Bilateral sagittal split osteotomies were made in the ascending ramus and body of the mandible of two adult cynomologus primates, and the dento-osseous segment was completely mobilized. A distraction device was fabricated from a Glen-Ross screw soldered between two mini bone plates. The bone plates were fixed by self-tapping screws to both right and left proximal and distal mandibular segments. Beginning 1 week postoperatively, both distraction plates were opened 1 mm every day until the mandible was advanced a total of 10 mm. Comparison of cephalometric radiographs and study casts prepared preoperatively, at the completion of the mandibular orthopedic advancement, and up to 12 weeks postdistraction, showed that mandibular advancement was successful and stable. There was radiographic evidence of bone filling the osteotomy sites, and there was no scar tissue formation or evidence of relapse.

Animals↗
PubMed1988

Cervical stabilization by plate and bone fusion.

Anterior stabilization with combined plate and bone fusion was performed after neural decompression on ten patients for spondylotic cervical myelopathy, and for radiculopathy or trauma in three patients. Medial corpectomy was performed at one to four levels. Iliac crest or fibular bone grafts were secured by plates anchored to the graft and adjacent vertebral bodies. All patients were placed in Minerva braces postoperatively. There was successful fusion in all cases, and no graft dislodgement or kyphosis. Early initiation of rehabilitation was achieved. Morbidity occurred in patients with severe spondylotic cervical myelopathy. This include respiratory depression requiring reintubation in 2/13 procedures, dysphagia (2/13) from loosening of the screws or prominent hardware and graft, and screw loosening (2/13). Neurological improvement was present in 85% (11/13) of patients. There was no deterioration of neurological function in any case. We conclude from this early follow-up that anterior bone fusion with supplemental plates provides effective stabilization for the unstable cervical spine. Greater morbidity risk exists in patients with severe spondylotic cervical myelopathy and spastic quadriparesis who required multilevel medial corpectomies and fusion.

Adult↗
PubMed1992

Evolution of bone inhomogeneity around a hole in an orthotropic plate of bone: theoretical predictions.

The problem of the evolution of bone inhomogeneity around a hole in a plate of bone with orthotropic symmetry is considered. The internal remodeling theory of Cowin and Hegedus is employed to show the existence of final inhomogeneity following stress concentration. The speed of remodeling around the hole and its variation with respect to distance is investigated. Results indicate that the effect of stress concentration around a hole is slightly less pronounced if bone is considered orthotropic rather than transversely isotropic. The speed of remodeling is found to be unaffected but the amplitude of inhomogeneity with respect to distance drops and disappears slightly faster if bone is considered orthotropic.

Bone Density↗
PubMed2003

The effect of divergent screw placement on the initial strength of plate-to-bone fixation.

BACKGROUND: Numerous implants exist that allow screws to be placed at varying angles for lag fixation or to fix additional fragments. This study determined how placing screws at different angles affects fixation strength. METHODS: Using a bone model, we first investigated the pullout strength of screws inserted at varying angles; then, we studied the strength of plate-bone constructs with end screws placed at divergent angles. RESULTS: Varying the screw angle from 0 to 10 to 20 degrees progressively weakened the screw pullout resistance. No additional decrease was found in varying the angle further. In contrast, the strength of fixation of plate to bone was higher for constructs with screws placed at 20 or 30 degrees off of perpendicular when tested in gap-open bending and axial compression (all p < 0.05). No such differences were found in torsion. CONCLUSION: The pullout strength with angled screws is reduced, but this does not translate into reduced strength of the bone-to-plate interface.

Analysis of Variance↗
PubMed2006

Periodontal effects of rapid maxillary expansion with tooth-tissue-borne and tooth-borne expanders: a computed tomography evaluation.

INTRODUCTION: The force delivered during rapid maxillary expansion (RME) produces areas of compression on the periodontal ligament of the supporting teeth. The resulting alveolar bone resorption can lead to unwanted tooth movement in the same direction. The purpose of this study was to evaluate periodontal changes by means of computed tomography after RME with tooth-tissue-borne and tooth-borne expanders. METHODS: The sample comprised 8 girls, 11 to 14 years old, with Class I or II malocclusions with unilateral or bilateral posterior crossbites Four girls were treated with tooth-tissue-borne Haas-type expanders, and 4 were treated with tooth-borne Hyrax expanders. The appliances were activated up to the full 7-mm capacity of the expansion screw. Spiral CT scans were taken before expansion and after the 3-month retention period when the expander was removed. One-millimeter thick axial sections were exposed parallel to the palatal plane, comprising the dentoalveolar area and the base of the maxilla up to the inferior third of the nasal cavity. Multiplanar reconstruction was used to measure buccal and lingual bone plate thickness and buccal alveolar bone crest level by means of the computerized method. RESULTS AND CONCLUSIONS: RME reduced the buccal bone plate thickness of supporting teeth 0.6 to 0.9 mm and increased the lingual bone plate thickness 0.8 to 1.3 mm. The increase in lingual bone plate thickness of the maxillary posterior teeth was greater in the tooth-borne expansion group than in the tooth-tissue-borne group. RME induced bone dehiscences on the anchorage teeth's buccal aspect (7.1 +/- 4.6 mm at the first premolars and 3.8 +/- 4.4 mm at the mesiobuccal area of the first molars), especially in subjects with thinner buccal bone plates. The tooth-borne expander produced greater reduction of first premolar buccal alveolar bone crest level than did the tooth-tissue-borne expander.

Adolescent↗
PubMed2005

Bone biological plate for stabilization of maxillary inferior repositioning.

AIM: Inferior repositioning of the maxilla to correct vertical maxillary deficiency has been one of the more unstable orthognathic procedures performed. Different surgical techniques have been proposed to stabilize downward movement of the maxilla. The aim of this study was to evaluate the skeletal stability of maxillary anterior downgrafting using bone biological plates in association to bone plates and bone graft for skeletal stabilization. METHODS: The records of 6 patients were evaluated cephalometrically, analyzing the presurgical, immediate postsurgical and long-term follow-up radiographs. All patients had one-piece Le Fort I osteotomy with anterior downgraft of at least 2 mm at point A. Any horizontal movement of the maxilla concomitant with the downgraft was no more than 5 mm. Rigid fixation with titanium miniplates and screws and with bone biological plate was used to stabilize the maxilla. In the sample of 6 patients, 3 underwent one-jaw (maxilla only) surgery and 3 two-jaw surgery. RESULTS: The mean surgical inferior downgrafting at point A was 5+/-1.4 mm (P<0.001) with a relapse of 0.16+/-1. 63 mm (3.2% of surgical movement). The mean surgical inferior downgrafting at the anterior nasal spine (ANS) was 5.66+/-1.36 mm (P<0.001) with a relapse of 0.41+/-1.56 mm (7.32% of surgical movement). Relapse in the vertical dimension failed to reach any statistical significance for all maxillary landmarks. CONCLUSIONS: Anterior downgrafting of the maxilla with this fixation method seems to be a stable and predictable procedure. The use of bone biological plates seems to substantially improve skeletal stability even if further investigations with a more consistent sample of patients is required.

Biocompatible Materials↗
PubMed1994

Effects of testosterone on skeletal growth in lambs as assessed by labeling index of chondrocytes in the metacarpal bone growth plate.

The effects of testosterone on the epiphyseal growth plate of metacarpal bones of growing sheep were evaluated in 20 rams, 20 wethers, and 20 wethers receiving subcutaneous testosterone replacement therapy. Two animals from each testosterone treatment group were slaughtered at 14-d intervals from 49 to 133 d, and then at 28-d intervals until 217 d, for a total of 10 slaughter ages. Immediately after slaughter, the cannon bones were dissected of extraneous tissue, weighed, and their lengths measured. Growth plates from the metacarpal bones were isolated and explants were cultured for 24 h in medium containing [3H]thymidine. After autoradiography, labeling index was calculated as the ratio of labeled to total nuclei in the resting and proliferative zones of the growth plate. Testosterone increased (P < .03) weight and length of the metacarpal bone. Increased bone length due to testosterone was associated, in part, with a higher (P < .05) labeling index in chondrocytes of the proliferative zone of the growth plate. Labeling indices in the resting zone chondrocytes of rams were higher near the time of puberty. Accelerated growth followed by cessation of growth occurs concurrently with puberty in males of several species and is accompanied by an increase in the blood concentration of testosterone. Testosterone may mediate this accelerated growth by first increasing bone growth and then depleting the source of stem cells in the cartilage growth plate, the site where growth in length of long bones occurs.

Aging↗
PubMed2003

[Therapeutic results of the proximal humeral neck fractures].

Good therapeutic results can be obtained by conservative treatments for the proximal humeral neck fractures. However, surgical treatment is sometimes required in patients with 2- or 3-part fractures (Neer's classification) in whom the reduction of the fracture is unable to be maintained by conservative treatments. In this study, we performed the surgical treatment using anatomical bone plate on these patients and evaluated the therapeutic results. The materials consisted of twenty patients. The surgical procedure was performed plate fixation using anatomical bone plate by delto-pectral approach. The postoperative follow-up period ranged from one year to eight years and six months (mean;three years and two months). No patient showed ununited fracture site or humeral head necrosis. The average range of motion in the shoulder was 172 degrees in elevation, 164 degrees in abduction, and ninth thoracic level in internal rotation. Favorable therapeutic results can be obtained by plate fixation using anatomical bone plate in patients with 2- or 3-part fracture of the proximal humeral neck. However, there is necessary in consideration to treat using anatomical plate in patients with severe osteoporosis.

English Abstract↗
PubMedDate not supplied

Reduction in plate strain by addition of an intramedullary pin.

OBJECTIVE: The purpose of this study was to determine the strain sparing effect of a bone plate and rod system compared with a bone plate alone. STUDY DESIGN: Mathematical analysis and in vitro modeling of implant-bone constructs. Implants were instrumented with uniaxial strain gauges. ANIMALS OR SAMPLE PREPARATION: Five pairs of canine femurs. METHODS: Bone plates were instrumented with two 350-ohm strain gauges. The bone plates were used to bridge a simulated fracture gap in five pairs of canine femurs. In one femur of each pair, a bone plate alone was used to bridge the gap; in the opposite femur, a bone plate and intramedullary rod combination was used. Each specimen was mounted on a custom jig and loaded in an axial servohydraulic testing machine. A constantly increasing compressive load was applied at the rate of 0.7 cm/sec. Strains at 400.5 N were recorded and analyzed using Wilcoxon's signed rank test. Mathematical modeling was done using parallel beam theory. RESULTS: Stress reduction in the plate and rod system was twofold compared with the plate alone (P = .059). As important, based on stress reduction in the plate, the fatigue life of the plate/rod system increased 10-fold over the plate system alone and was greater than 10-fold at higher absolute stress values. Mathematical analysis of the plate/rod system was similar to that seen with the in vitro analysis. CONCLUSIONS: The combination of a bone plate and intramedullary pin was superior in reducing plate stress when compared with the plate alone and functioned as two beams acting in concert. CLINICAL RELEVANCE: Stabilization of comminuted fractures by bridging the zone of fragmentation with a bone plate without anatomic reduction of each fragment is a useful method of managing this type of injury. Addition of an intramedullary pin reduces the stress applied to the plate and thereby extends the fatigue life of the bone plate.

Animals↗