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Distraction osteogenesis using modified external fixation devices in five dogs.

Distraction osteogenesis was used to treat five dogs with limb deformities or limb shortening. The affected bones underwent osteotomy, and modified external fixators were attached. Complications included pin loosening, implant breakage, and soft-tissue contracture. Adequate limb length was attained in all cases, but clinical results varied from poor to excellent. Two dogs were not lame after the procedure, two dogs had improved function but were still lame, and one dog had complications necessitating amputation.

Animals

Metatarsal lengthening by distraction osteogenesis: a report of two cases.

Two cases of lengthening of metatarsals by distraction osteogenesis are reported. One of these cases is an acquired deformity of the first metatarsal; the other is a congenital short fourth metatarsal. By following the principles set forth by Ilizarov, it was possible to lengthen the metatarsal bones and surrounding soft tissues without open lengthening of tendons or secondary bone grafting of the distraction gap. We believe this method is an improvement over previously described methods of metatarsal lengthening.

Adolescent

Control of interfragmentary micromotion in Ilizarov distractional osteogenesis.

Growth of the regenerate is affected by various factors during the course of Ilizarov distractional osteogenesis. One of the chief biomechanical factors that influences the quality and rate of bone formation is fixator stiffness. A four-ring Ilizarov apparatus was configured around a synthetic tibia. In a series of trials involving a uniform axial load, different transfixing wire tensions, and the separation of paired proximal and distal rings, fragment displacement was measured. Preliminary results suggest that the effect produced by the distraction of ring pairs on interfragmentary micromotion is as significant as pretensioning of the wires.

Biomechanical Phenomena

Transverse Tibial Transport for Limb Salvage in Ischemic Lower Extremity Disease: Technique, Mechanisms, and Clinical Outcomes-A Systematic Review.

Transverse tibial transport (TTT) is a surgical technique derived from Ilizarov's distraction osteogenesis principles that stimulates angiogenesis and microcirculatory regeneration in the ischemic lower limb without directly manipulating macrovascular anatomy. By creating a proximal tibial cortical bone window and distracting it transversely using an external fixator, TTT triggers converging cascades of growth factor release, endothelial progenitor cell mobilization, and immunomodulation that translate into improved distal limb perfusion and wound healing. Combined TTT plus endovascular therapy improves amputation-free survival versus endovascular therapy alone. Prospective randomized trials and standardized international protocols are needed to consolidate TTT's role in multidisciplinary limb salvage pathways.

Humans

Rigidity of half-pins for the Ilizarov external fixator.

The success of the Ilizarov technique is due to the combination of the biomechanics of its external fixator and the biology of distraction osteogenesis. The stability and stiffness of the conventional Ilizarov fixator is attributed to its use of a K-wire cross structure. The disadvantages of this structure include pain, and possible neurologic and vascular injuries when the wires are introduced into crucial neurovascular areas, as well as increased frame complexity and construction. Reducing the number of wires decreases these problems, but also decreases the stiffness of the system. Hybrid (wire and half-pins) Ilizarov fixators and half-pin fixators are also being used in an attempt to alleviate these problems. Half-pins have been described by Fleming et al. and Green as causing minimal transfixation of the surrounding soft tissues and capable of and being inserted into anatomically safe areas. The stiffnesses of the hybrid systems have not been measured. This study reports on the stiffness of different wire and half-pin systems that were biomechanically tested in axial loading, anterior-posterior bending, medial-lateral bending, and torsional loading. The results demonstrated that the conventional Ilizarov fixator with wires possesses a high axial stiffness, whereas the fixator with half-pins possesses higher stiffness under bending and torsional loads. To obtain adequate stability, the use of hybrid Ilizarov frames with one wire and two or more half-pins (5 or 6 mm in diameter), or larger half-pin frames (5 or 6 mm) with three pins is recommended.

Biomechanical Phenomena

[The Ilizarov apparatus in pseudoarthrosis of the long bones].

Distraction osteogenesis with the Ilizarov technique is effective in achieving bone healing in both atrophic and infected pseudoarthrosis. In 10 patients with atrophic and 14 with infected pseudoarthrosis treated by this method, solid bone union with reconstruction of anatomical limb length was achieved in all except 1. They ranged in age from 16-80, with a mean of 44. The mean treatment time was 9.4 months for the femur, 4.5 months for the tibia and 8 months for the radius. Patients could be actively rehabilitated all during the course of treatment and they achieved independent ambulation by the time the apparatus was removed. There were no complications.

Adolescent

Noninvasive vascular monitoring during limb lengthening.

Transcutaneous wires and pins in wire-tension Ilizarov external fixators provide frame stability, transfix and transport bone segments, produce distraction, and stimulate transosseous osteogenesis. Vascular compromise by the transfixing pins and wires is nevertheless an ongoing possibility. Based on earlier studies of a two-phase method of measuring vascular blood blow, noninvasive vascular monitoring was performed on three patients undergoing Ilizarov method limb lengthening.

Bone Lengthening

Treatment of bone and soft tissue defects in infected nonunion.

In the treatment of infected pseudarthroses the general principles of osteitis treatment are applied. This includes radical excision of pseudarthrotic and infected bone tissue, and of diseased surrounding soft tissue. External fixation devices are the preferred method of stabilization of the bone. Based on the data of a retrospective study of 31 Papineau procedures, 65 local flap transfers, and 46 free flap transfers we found that the Papineau procedure works in minor bone and soft tissue defects. Unstable scar formation is a major disadvantage of this method. Local muscular flaps are indicated in the treatment of soft tissue defects in the proximal and medial portions of the lower leg. A prerequisite for free flap transfers is the availability of trained personnel and suitable technical equipment. The option is limited by the patient's vascular situation. This kind of tissue transfer seems to be superior to other methods. For the substitution of bone defects corticocancellous bone transplantation may be used. A promising alternative method to deal with extensive bone defects is osteogenesis produced by callus distraction.

Bone Transplantation

[Electron microscopic study of the characteristics of skeletogenic tissue differentiation during distraction osteosynthesis].

Electron microscopic examination of the regenerating tissue was performed after distractional osteosynthesis carried out by the method of G. A. Ilizarov. The results showed osteogenesis to occur on the basis of the fibrous tissue formed in diastasis. The observed zones of the regeneration typical of distractional osteosynthesis are due to functional stimulation (tension) resulting in the arrangement of collagen fiber bundles and bone trabeculae in the direction of the extension forces. Cells of the skeletogenic tissue, between the bone fragments are also arranged with their longitudinal axis along the collagen fibril bundles. The ultrastructural pattern of the osteogenesis after distractional osteosynthesis reflects the intensification of the synthesis of glycosaminoglycan-protein complexes forming the main substance of the bone tissue.

Animals

Bone formation after distraction osteotomy of the radius in sheep.

Gradual distraction by external fixation was performed one week after osteotomy of the radius in 12 sheep. Bone regeneration in the distraction area was studied by light and electron microscopy. One week after starting the distraction the gap was composed of hematopoietic cells and fibroblasts. The collagen production had already started and it continued actively throughout the distraction period. The collagen produced by the fibroblasts in the central interzone of the gap was organized according to the direction of the distraction. The osteoblasts were lined up along the collagen bundles and osteoid formation was most active around the capillaries. Mineralization started two weeks after the beginning of the distraction. After cessation of the distraction, separate groups of cartilaginous cells were found in some specimens among the newly formed bone. Our findings suggest that osteogenesis as a result of gradual distraction occurs through the whole distraction area with preceding formation of organized collagen matrix. The bone structure in the distracted segment represents an organized lamellar structure at an early stage of the osteogenesis.

Animals

[Ilisarov ring fixation and its technical application].

The Ilisarov ring fixator is an extremely versatile external fixation device. There is a wide range of indications for its use, e.g. fractures, pseudarthroses and non-unions, large defects, deformities and limb shortening. The device consists of rings or half-rings, which are connected to each other by threaded rods or plates and to the bone by wires under tension. This design allows neutral fixation, compression or distraction of the bone fragments. Because of its low axial stiffness at low loads and increased stiffness at higher loads, this fixator promotes osteogenesis and reduces strain on the tissues in functional treatment. Surgical intervention for its application is minimally invasive. This is a useful addition to the orthopaedic surgeon's armamentarium, providing proper attention is paid to preoperative planning, the principle rules of frame design and wire insertion technique, and postoperative management.

Biomechanical Phenomena

[The value of ultrasonography in monitoring limb lengthening].

The authors attempted to assess the value of ultrasound for monitoring of the new bone formation at the site of distraction in patients undergoing limb lengthening after Bastiani. Twenty patients were assessed; 12 cases of femur lengthening and 8 cases of tibia lengthening. It was found, that ultrasound allowed to detect the new bone formation visible as hyperechogenic foci as soon as 4 to 14 days postoperatively, while regular radiology showed this only 4 to 8 weeks after operation. Detection of the new bone formation at the site of lengthening permits, in authors opinion, to choose an optimal onset of distraction and its pace according to the speed of bone formation. Regular ultrasound monitoring prevents premature bone union or disintegration of the newly generated bone in case of to slow or to fast distraction respectively. In two cases sonography early demonstrated cystic changes at the location of distraction. It also permits detection of an axial displacement of the fragments of bone in every case.

Adolescent

[Distraction epiphyseolysis. An experimental study for bone lengthening. Part I (author's transl)].

Distraction epiphyseolysis is an operation for bone lengthening in children and adolescent which is often performed in Russia. Our experimental examination in rabbits has shown a lot of problems with this method. With distraction epiphyseolysis it is possible to get a primary lengthening of bone and a soon consolidation of the distraction-cleft. During further growth this primary lengthening is going lost. After the end of growth there was no significant difference between operated and non operated bone. The cause of the growth-disturbance is discussed in a further publication guided by histological findings.

Age Factors

Lengthening of mandibular body by gradual surgical-orthodontic distraction.

Lengthening of the mandibular body in two dogs was achieved with a technique that involved osteotomies and the use of an experimental orthodontic appliance; the approximation of the resected mandibular segments was maintained. There was no damage to the mandibular nerve and no conspicuous alterations of the nerve fibers. On the basis of results in experimental studies, the technique is proposed for use in correction of large discrepancies in length in persons with excessive mandibular retrusion.

Animals

Delayed distraction in bone lengthening. Improved healing in lambs.

We compared delayed distraction (DD) with immediate distraction (ID) in bone-lengthening. Open femoral diaphyseal osteotomy was performed on 24 three-month-old lambs, and external distractor fixators were applied. In the ID group (n 12), distraction commenced on the first postoperative day; in the DD group (n 12), distraction was delayed until the tenth day after surgery. In all the animals, the femur was lengthened by 2 cm at the rate of 1 mm/day. The animals were killed 1, 2, and 3 months postoperatively. Radiography and densitometry of the lengthened callus showed that DD, compared with ID, improved the quality of the callus with quicker, denser, and more homogeneous bone formation.

Animals