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At least 217 records · Page 12Linked to original sources
PubMed1993

Experimental effects of bone plating in infancy on craniomaxillofacial skeletal growth.

The potential effects of mini- and microfixation on craniofacial development was investigated in an animal model. Twenty-four rabbits had amalgam markers placed bilaterally at the lambdoid, coronal, and frontonasal sutures at 28 days of age. In group 1, plating was not done and served as controls. In groups 2 to 4, single 2- and 4-hole microplates and 4-hole miniplates were fixed across the left coronal suture. The right suture was not plated. After 6 months, intermarker distances and craniofacial angles were measured radiographically. Coronal sutures underneath the plates were also histologically evaluated. Plating across the coronal suture resulted in local anteroposterior constriction of marker distances that did not differ with the type of fixation used. More distant markers, however, were increased in all specimens as a compensation and, as a result, the cranionasal length of all groups were similar. No change in craniofacial angles was observed from that of the controls. Sutural morphology on the side of fixation was altered with decreased widths, cellular numbers, and bone deposition. These experimental results demonstrate that early plate application in a normal calvarium results in local growth restriction that can be overcome by regional bone growth compensation.

Analysis of Variance↗
PubMed1995

Five-year follow-up of mandibular reconstruction with hydroxylapatite and the mandibular staple bone plate.

PURPOSE: To evaluate the results of hydroxylapatite augmentation of the mandible followed by placement of the mandibular staple. PATIENTS AND METHODS: Sixty patients 5 or more years postsurgery were evaluated. Patients were followed yearly with clinical and radiographic examinations. RESULTS: The decrease in augmentation height was 2.8 mm (33%) after the first year and only minimal in the following years. The following problems were seen: hyperplastic tissue around posts (eight patients), small dehiscences were seen in the saddle area after 2 years (11 patients), large dehiscences with significant hydroxylapatite loss in five patients. One patient needed a secondary augmentation. CONCLUSION: Prosthetic stabilization and function were excellent throughout the study period and there was a uniformly high degree of patient satisfaction.

Adult↗
PubMedDate not supplied

[Osteosynthesis of crural bone fractures using bone plates with pegs].

A metal plate with pegs for osteosynthesis was designed and introduced into practice for the treatment of diaphyseal fractures of the leg bones. Studies for appraising the tension-deformity condition proved that installation of 20 cone-shaped pegs on the inner surface of the plate increases the stability of fixation 3.6-fold. Besides, the cone-shaped pegs facilitate maintenance of intactness of the vessels of the periosteum and soft tissues as a result of which the conditions for healing of the fractures improve. Operations were carried out on 43 patients, in 41 with good outcomes. External immobilization was not applied in the postoperative period, early restorative treatment was conducted.

Adolescent↗
PubMed1977

The influence of electric potentials on plated bones.

Twenty-seven rabbits were treated with bilateral tibial osteotomy and compression plates. One tibia in each animal received three to 15 microamperes constant direct current for 21 days. The breaking strengths of the stimulated tibiae were higher in 19 animals, as compared to controls (70.4% stimulation rate). The mean value of the additional maximum stress to break the stimulated tibiae was 0.73 kg. Fifteen other rabbits were similarly treated but with electrical stimulation being applied to only one tibia in each animal. There was an increase in endosteal and periosteal callus formation and greater vascularization on microangiography of the callus and the stimulated side. The fissure gap at the osteotomy site was smaller, and bone in the fissure was mature lamellar bone only on the stimulated side. The uptake of fluochromes was greater on the stimulated than control untreated side. Both tibiae in each of five rabbits were doubly fixed with compression plates. A simulated piezoelectric potential was applied to one tibia in each animal. There was a 20 per cent higher calcium and phosphate content of the stress protected cortex, as well as an increased uptake of fluorochormes, in the stimulated tibia as compared to that of the control tibia in three out of five of the animals.

Animals↗
PubMed1985

A follow-up study of apicoectomized teeth with total loss of the buccal bone plate.

Opinions differ as to whether or not teeth with advanced marginal bone loss should be subjected to periapical surgery. The purpose of this retrospective investigation was to study the results after apicoectomy on teeth that showed total buccal bone loss at the time of the operation. The material consisted of twenty-seven teeth in 27 patients, fifteen males and twelve females, 23 to 63 years old at the time of the operation. The observation time varied from 0.5 to 7 years (mean, 3 years). Ten operations (37%) were regarded as successful, nine (33%) as uncertain, and eight (30%) as unsuccessful. The success rate was not so low that an apicomarginal communication should be regarded as a contraindication for apicoectomy. Apicoectomy should be performed, especially if the alternative is an otherwise unnecessary prosthetic reconstruction.

Adult↗
PubMed1997

[Evaluation of impaction on bone nail and bone plate of the pertrochanteric fracture].

PURPOSE OF THE STUDY: Impaction in pertrochanteric fracture sites is a well known phenomenon; the screw-plate system is designed to stabilise the fracture. Although easier to use, the risk with the nail-plate system is postoperative penetration of the nail into the joint. The present study was conducted to determine the exact conditions of the impaction, and to identify possible ways to improve the nail-plate system. MATERIAL-METHOD: The study included 129 cases of pertrochanteric fracture, excluding sub-trochanteric fractures. All fractures were fixed with a 130 degrees angulated nail-plate. In all cases, consolidation was uneventful after 8 to a 12 weeks. The anatomical type of fracture, i.e. stable or unstable, was determined according to the size of the intermediary fragment, including the trochanter minor. The displacement was measured as the difference between the length of the nail and the length of the femoral head and neck measured along the axis of the femoral neck. The parameters examined were: fracture stability degree, bony mineralisation (Singh Index), nail length, femoral neck, length nail position in the femoral head, and above all, fracture reduction. All these parameters were computerised and compared using Stat View statistics software. RESULTS: Impaction was observed in 43 per cent of cases. Among these, 25 per cent were rated as slight (1 to 5 mm), 18 per cent as moderate (over 5 mm) and 9 per cent as marked (10 to 25 mm). Impaction was associated with demineralisation of the bone tissue (p = 0.001). The anatomical classification of the fracture was not a determining factor (p = 0.19), as marked displacements were also recorded in stable fractures. A posterior and inferior position of the intramedullary nail in the femoral head is one of displacement determining factors (p = 0.004, two-sided 1 test). Valgus over-correction is the most important factor, especially when it is associated with bony demineralisation (p = 0.02) and an inadequately centred intramedullary pin (p = 0.02). Shorter the femoral neck, and shorter the nail, greater was the frequency of nail articular penetration. DISCUSSION: The risk of articular penetration therefore reaches 15 per cent in petrochanteric fractures repaired with a nail plate, set at an angle of 130 degrees. A short neck, a cervicodiaphyseal angle superior to 140 degrees, and demineralisation are the three determining parameters. Stable or unstable fracture has in fact little effect on displacement incidence, and therefore does not, on its own, warrant the use of a prosthesis in comminuted fractures. The authors compared their results to literature on progressive sliding system: the incidence of complications associated with this type of fracture treatment is identical, but the determining parameters are different. CONCLUSION: The study shows that the nail-plate is efficient and provides simple and solid fracture fixation. However, this osteosynthesis material needs to be modified in order to improve its fixation in the femoral head.

Adult↗
PubMed1998

The subchondral bone plate.

Pauwels (1965) and subsequent workers in the same field have shown that the distribution of the subchondral density within a joint surface can serve as a parametric measurement which reflects the main stress acting on a joint. Our own investigations on anatomical specimens have demonstrated that this subchondral mineralization does indeed show regular distribution patterns from which conclusions about the mechanical situation within an individual joint may be drawn. Since radiographical densitometry and histological methods are only available for determining the adaptive reaction of the bone to the particular mechanical situation in a joint after death, the information obtained applies only to an end situation and tells us nothing about the development of the changes with time. Furthermore, investigations carried out on human specimens by radiographical densitometry mostly apply to samples of a particular age, since such specimens can be acquired only from departments of pathology, forensic medicine or anatomy. The functional reactions of the bone tissue to repeated long-term changes in the loading--lengthy immobilization and subsequent remobilization, for instance, or heavy loading over a considerable period of time--cannot be followed by any ordinary method in experimental animals, since the death of the animal is a prerequisite for the precise quantitative examination of the bone tissue. This applies also to attempts to follow the process by means of animal experiments. CT OAM has been developed as a method which, based on CT, can provide a surface representation of the 3-D density distribution in the joints of living subjects. Comparative studies were carried out to establish and confirm the validity of the procedure. These have shown (1) that the results obtained from anatomical specimens are identical with those obtained in the living; (2) that secondary CT sections are suitable for evaluation and that the spectrum of joint surfaces examined can be extended to include the whole joint (if this were not so, effects caused by the apparatus--particularly the partial-volume effect--would render the procedure impossible); and finally (3) that the distribution of the Hounsfield density within the subchondral bone represents the distribution of the mineralization. The mineralization patterns found by us in different joints of normal subjects have shown that these patterns can be brought into line with current models of joint mechanics. The radiocarpal joint, for instance, has revealed the various types of loading occurring within physiological limits. Information has also been obtained about the age-related changes taking place in the hip, wrist and ankle joints. The increase of the total mineralization in gymnasts can be related to the qualitative and quantitative adaptation to an increased peak loading, and reduced mineralization to a lengthy reduction in use during, for instance, postoperative immobilization. In groups of patients with various diseases of mechanical origin (shoulder instability, malalignment of the main axis, defective repositioning of healed fractures, rupture of the rotator cuff, meniscectomy or rupture of the anterior cruciate ligament), a pattern of mineralization is found which is different from the normal picture. These findings reflect the abnormal mechanical situation. The mineralization pattern of the femoropatellar joint has revealed the differing etiologies of medial and lateral cartilage damage and the examination of patients with lunatomalacia has made it possible to recognize a genetic disposition. The postoperative comparison of the mineralization patterns of patients with genu varum who have undergone a correction osteotomy and the results of animal experiments on various procedures for reconstructing the anterior cruciate ligament or a primary replacement of the meniscus, have produced results which make it possible to judge the success or failure of the operation. (ABSTRACT TRUNCATED)

Calcification, Physiologic↗
PubMed2000

Experimental study of effect of stress-relaxation bone plate on fracture healing.

OBJECTIVE: To study the change of the stress shi elding rate of stress-relaxation plate in vivo and its influence on fracture he aling. METHODS: The diaphyses of bilateral tibias in 70 New Zealand ra bbits were osteotomized and fixed with stress-relaxation plates (SRP, the SRP g roup) and rigid plates (RP, the RP group), respectively. The fracture healing pr ocess in these 2 groups was investigated by radiography, light and polarized l ight microscopy and biomechanical test at 2 to 48 weeks postoperatively. RESULTS: Early after fixation the stress shielding rate was abo ut 70% in both groups. While in the SRP group the stress shielding rate decrease d gradually as time passed, which was significantly lower than that of the RP gr oup (P<0.05) by the end of the 8th postoperative week, and stabilized at the level of about 27% at 36-48 weeks after fixation. Abund ant external callus associated with the formation of cartilaginous callus could be observed in the SRP group at 2-4 weeks postoperatively. The transformation o f the callus into the lamellar bone began at 8-12 weeks, the collagen gradually arranged in order, and the mechanical nature of the united bone was gradually s trengthened, too. In the RP group, the external callus was scarce at the early s tage of fracture healing, and the callus remodeling at the late stage of fractur e healing was dominated by bone absorption. The ultimate bending strength (UBS) was only 57.95% of that of the normal by 48 weeks. CONCLUSIONS: The decrease of the stress shielding rate of SRP i n vivo was well interrelated with the time of fixation. The application of SRP c ould promote the callus formation and bone reconstruction thus to favor the reco very of the mechanical strength of the united bone.

Journal Article↗