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 51,768 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Our continuously evolving understanding of bone biology has led to a new approach to plate fixation. In comminuted fractures, anatomical reduction of all fragments is no longer a goal in itself. Preservation of the viability of the bone fragments seems to be the key to unimpaired fracture healing in internal fixation. The rapid integration of unreduced but vital fragments into the fracture callus functions as a bio-buttress system and prevents fatigue fracture of the implant. To realize the new concept of biological internal fixation, the limited contact dynamic compression plate, which minimizes vascular damage to the plated bone segment, has been developed.
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PMID:[Limited Contact Dynamic Compression Plate (LC-DCP)--biomechanical research as basis to new plate design]. 154 32

In five straight-stemmed, proximally porous-coated femoral components that were retrieved at revision arthroplasty from patients who had radiographic and clinical evidence of loosening, there was growth of bone into the porous coating. The components had been inserted during a primary arthroplasty in one woman and four men. The patients ranged in age from thirty-seven to sixty-seven years. Three patients were heavy, and all five were active. All patients had had an excellent early result from the initial arthroplasty; at the one-year follow-up, the mean Harris hip score had been 91 points. Pain in the hip developed in all of the patients, between one and three years after the index procedure. Initial radiographs had revealed excellent position and fixation of the prosthetic components, but the components then subsided between one and three and one-half years after the index procedure. All of the femoral components were found to be grossly loose at the revision operation. Nevertheless, all of the prosthetic components demonstrated growth of bone into 4 to 44 per cent (mean, 24 per cent) of the pore spaces available for ingrowth. Woven bone and fracture callus were found in the curettings from the proximal part of the femur. The findings in these five patients suggest that late failure of uncemented porous-surfaced femoral components can occur despite the presence of extensive ingrowth of bone. These failures may be the result of fatigue fractures of the trabeculae of the osseous ingrowth into the porous surfaces. Caution is warranted in the liberal use of these prosthetic components in heavy, active patients.
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PMID:Ingrowth of bone in failed fixation of porous-coated femoral components. 152

The continually evolving understanding of bone biology and the analysis of clinical complications have led to a modified approach in internal fixation using plates. Anatomical reduction of the fragments in comminuted diaphyseal and metaphyseal fractures itself is no longer a goal. Important reduction aims are the correct length of the bone, and axial and torsional alignment. The preservation of the viability of the bone fragments is the key to unimpaired fracture healing. The primary stability of an osteosynthesis seems to be of minor importance for bone healing. More important is the rapid integration of unreduced but vital fragments into the fracture callus which buttresses the fracture area opposite the plate reducing the risk for overload and fatigue failure of the implant. Additional primary bone grafting leeds to local vascular disturbance of the bone and is rarely indicated. Indirect reduction technique with the aid of the fracture table or the distractor and a minimal but optimal use of implant material is the new concept to achieve undisturbed fracture repair in metaphyseal and diaphyseal fractures. In articular fractures the anatomic restoration of the articular surface can be obtained by the combination of indirect reduction technique (ligamentotaxis, soft tissue taxis) and accurate direct reduction of certain strategic fragments. Modifications of the plate design (limited contact, point contact) which minimize additional vascular damage to the bone help to accomplish this new concept.
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PMID:[The biological plate osteosynthesis]. 797 46

The viability of osteocytes can be demonstrated in sawn decalcified sections of bone by their lactate dehydrogenase activity. In the cancellous bone of the femoral head, the proportion of lacunae containing viable osteocytes decreased from 88 +/- 7% (mean +/- SD) at 10-29 years to 58 +/- 12% (P < 0.001) by 70-89 years. Viability in the second lumbar vertebra was 88 +/- 3% in subjects aged 25-90 years and did not decrease with age. Mean osteocyte viability in the femoral head of 21 hip fracture patients aged 72-94 years was 58 +/- 21%, similar to controls of a similar age, though there was greater variation and, in five patients, osteocyte viability was less than 25%. In hip fracture patients, microfracture callus incidence correlated positively with osteocyte viability, with little or no fracture callus observed if the bone viability was low. Ultimate compressive strength did not correlate with osteocyte viability. In the femoral head there is gradual, age-related reduction in osteocyte viability that can be more pronounced in hip fracture. Osteocyte death may affect bone quality by impairing repair of fatigue damage.
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PMID:Osteocyte death and hip fracture. 827 64

The process of fracture healing restores the biological and mechanical state of the bone tissue. In contrast to other tissues, bone has the unique capacity to heal through a real repair process resulting not in a scar but in a regular reconstitution of its original tissue structure. During the last two decades, the understanding of bone biology continuously evolved leading to the new concept that preservation of the viability of the bone fragments is the key to unimpaired fracture healing. The biological fracture management provides environmental conditions that allow the natural healing process to occur as quickly and undisturbed as possible. In comminuted diaphyseal and metaphyseal fractures, the reduction process strives for restoration of proper length and axial and torsional alignment. Thereby, the reduction technique is mainly indirect, i.e. without direct visualization of the fracture area. The primary stability of an osteosynthesis seems to be of secondary importance for achieving sound bone healing. Stabilization can either be performed with an intramedullary nail or a bridging plate. The new biological plating technique imitates the concept of intramedullary fixation. It requires the use of a long implant working with improved leverage. This reduces both, the loading of the screws and the loading of the plate. The good healing capacity of viable fragments and their integration into the fracture callus protects the implant (especially a plate) from fatigue failure. To help to accomplish this new concept of biological plate fixation, new implants such as the Locking Compression Plate (LCP) have been introduced. The mechanical efficiency of this new plate generation is enhanced due to its possibility for angular stability screw insertion; load transfer by friction can be replaced by a load transfer by interlocking (internal fixator), reducing the biological interference of this implant (no contact implant). Functional rehabilitation with painfree mobilization needs to be performed carefully because the loading capacity of the biological plate osteosynthesis is low until radiological signs of bone healing via callus formation is visible. Clinical signs of overload and radiological indicators of potential mechanical failure of the fixation have to be identified by the general practitioners, and the compliance of the patient has to be controlled during the rehabilitation phase to avoid complications after biological internal fixation.
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PMID:[Biological internal fixation -- guidelines for the rehabilitation]. 1475 51