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Results for “LEG LENGTHENING”

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At least 163 records · Page 9Linked to original sources
PubMed1995

Leg lengthening and glycosaminoglycans in the rabbit knee.

We investigated the effects of tibial lengthening by callotasis on glycosaminoglycan (GAG) metabolism of the knee articular cartilage in 30 rabbits. The distraction rate was 1 mm per day. On the right side, the daily distraction was in 2 steps, while on the left it was in 120 steps. The animals were divided into 3 subgroups based on length gain; 10, 20, and 30 percent, respectively. The knee joint fluid and medial tibial cartilage were examined by quantitative analysis of the GAG content and/or synthesis. The immunoreactivity for chondroitin sulfate in the cartilage was also examined by immunohistochemistry. For all length gains, the GAG concentration in the synovial fluid was higher on both sides than in controls, with no difference between sides. The GAG content and synthesis in the cartilage on the 2-step side decreased gradually with increasing length. On the 120-step side, the content did not differ from control values in any length gain, and the level of synthesis at 20 and 30 percent lengthening was higher than the control level. Our findings indicate that the alterations in GAG metabolism are attributable to increased mechanical stress on the articular cartilage, suggesting a moderate increase on the 120-step side compared to an excessive one on the 2-step side.

Animals↗
PubMed1998

The diameter of callus in leg lengthening: 28 tibial lengthenings in 14 patients with achondroplasia.

We investigated the relation between callus diameter during bone distraction and the occurrence of late fracture and deformity. We retrospectively reviewed 28 tibial lengthenings in 14 patients with achondroplasia. The minimal diameter of the lengthened zone was measured on radiographs, when the sliding mechanism of the lengthening device was released, and the callus diameter ratio in two planes (CDR; diameter of the callus/diameter of the tibia at the level of the osteotomy end) was calculated. The CDR correlated negatively with the distracted length. Late fracture or late angular deformity occurred in 6 of the 28 lengthenings. When the CDR was 85% or more in both planes, these complications did not occur, but when the CDR was 80% or less in either plane, they occurred in 6 of 20 bones. Careful attention should therefore be given not only to the continuity of the callus but also to its diameter.

Achondroplasia↗
PubMed2001

Response of the physis to leg lengthening.

UNLABELLED: The physeal response to limb lengthening by callotasis was investigated in an animal model by measuring 1) the growth rate using an oxytetracycline labelling technique, 2) histomorphological changes, and 3) proliferative cellular activity using bromodeoxyuridine. An osteotomy without lengthening stimulated growth at the physis. At 20% lengthening, regardless of the rate of distraction, no significant changes were detected. However, the growth rate was drastically reduced after 30% or more of lengthening and in 50% of cases there was evidence of premature closure of the distal growth plate. CLINICAL RELEVANCE: Caution should be exercised in carrying out high percentages of lengthening of children's bones.

Animals↗
PubMedDate not supplied

Effects of pulsed electromagnetic field stimulation on distraction osteogenesis in the rabbit tibial leg lengthening model.

The purpose of this study was to determine whether exposure to pulsed electromagnetic field (PEMF) would shorten the healing time of regenerate bone in a rabbit tibial distraction model. Beginning 1 day after surgery, mid-shaft tibial osteotomies, stabilized with external fixators, were distracted 0.25 mm twice daily for 21 days and received either no exposure (sham control) or 1 hour per day exposure to low-amplitude, low-frequency PEMF. Tibiae were tested for torsional strength after 9, 16, and 23 days post-distraction. PEMF-treated tibiae were significantly stronger than shams at all three time points. By 16 days post-distraction, the PEMF group had achieved biomechanical strength essentially equivalent to intact bone. Shams did not achieve normal biomechanical strength even after 23 days post-distraction. In this tibial distraction model, short daily PEMF exposures accelerated consolidation of regenerate bone. Clinical usefulness awaits testing.

Animals↗
PubMed1992

Canine leg lengthening by the Ilizarov technique. A biomechanical, radiologic, and morphologic study.

The mechanical properties of canine tibias lengthened by the Ilizarov method as well as the degree of healing--as determined by the osseous appearance of the limbs using three imaging modalities--were examined as a function of fixator application time. Sixteen mongrel dogs had right tibial lengthening using a two-ring Ilizarov external fixator. The average lengthening was 27 mm. Four groups of four animals were killed at four, six, eight, and ten weeks after the completion of lengthening. The operated and contralateral tibias were examined with biplanar roentgenography, computerized tomography, and technetium scintigraphy. The torsional strengths of the tibias were then determined and histologic analysis was performed. There was considerable variation in the healing rate of the lengthening sites, both within and among groups. Histologic analysis and results of the imaging modalities revealed different degrees of development of the lengthening sites among members of the same group. Two types of mechanical behavior were seen, corresponding to completely and incompletely ossified lengthening zones. The strongest samples were those that had ossified across their lengthening sites by four or six weeks. The degree of recorticalization of the new bone and the extent of formation of a marrow space correlated well with increased torsional strength. The average strength of the fully ossified bones decreased progressively with time, paralleling a decrease in cortical thickness outside the lengthening zone. This seems to be a consequence of stress shielding by the fixator and disuse by the animal.

Animals↗
PubMed1990

Leg-lengthening procedures. A historical review.

While there are new techniques for lengthening long bones, there are, nevertheless, contraindications and preoperative considerations for lengthening the femur or tibia, such as the presence of acetabular dysplasia, fixed deformity around joints, peripheral vascular and metabolic bone disease, and the age of the patient. Lengthening a long bone may be associated with many complications, especially in a congenitally short bone. It is important to anticipate and prevent complications, especially nonunion, subluxation of joints, muscle contractures, and neurologic complications. Lengthening of the femur and tibia are not for the occasional operator. However, as Bosworth noted in 1938, attention to great detail when lengthening the bone and skilled and detailed postoperative care will allow excellent results to be obtained. Time alone will tell what, biologically, is the best method for lengthening a long bone.

Bone Lengthening↗
PubMed1987

[Ultrastructural characteristics of elastogenesis in the major arteries of the canine hindlimb during leg lengthening].

In mature dogs ultrastructural peculiarities of elastogenesis in femoral and anterior tibial arteries have been studied at various stages of the bone elongation after Ilizarov method. From the end of the 1st week of distraction, metabolic activation of intimal smooth muscle cells is revealed, from the 2d week--in the middle tunic, and on the 5th-6th week--fibroblasts of adventitia of the arteries investigated, directed to biosynthesis of intracellular predecessors of elastin and microfibrils of the elastic fibers. This results in activation of elastogenic processes, elastic structures in all three tunics of the arteries are observed to newly form and rearrange. The factor that stimulates and maintains elastogenesis is strain of extension, that occurs in the vessels during the experiment. Elastogenesis in the major arteries, when the extremity is elongated, has much in common with development of elastic components in the vascular wall in animals during the process of physiological growth.

Animals↗
PubMed1984

[Ultrastructural features of femoral artery myocytes during experimental leg lengthening].

Femoral arteries in mature dogs have been studied electron microscopically at various stages of the shin lengthening performed after G. A. Ilizarov method. Certain ultrastructural signs demonstrating biosynthetic and secretory activation of myocytes directed to intensification of elastogenetic processes have been revealed. Immature elastic fibers are forming around myocytes as aggregations of microfibrils, later accumulations of amorphous material appear in them. On the 28th, 42d days of distraction, hyperproduction of intra- and extracellular vesicles is noted, as well as that of intracellular matrix. Cytoplasmic islets of myocytes and intercellular connections increase in number. In the subintimal layer, of the tunica media and at its border with adventitium, longitudinally situating fasciculi of smooth muscle cells are forming. The myocytic ultrastructural peculiarities noted, the new formations of elastic elements depend, at early stages of the experiment, on changes of regional hemodynamics, and at advanced stages - also on the effect of longitudinally acting tension stress.

Animals↗
PubMed1983

Leg lengthening by closed metaphyseal corticotomy.

A new method of limb lengthening is presented which can be used after closure of the epiphyses. It consists of interruption of the cortex by a closed technique at the metaphyseal level through a 1 cm incision. Fixation and progressive distraction are achieved by means of a special encircling external fixation device using crossed wires under tension. The rationale and technique are described and the results are reported and illustrated. These show that the method is more reliable, quicker and has fewer complications than the standard techniques.

Adolescent↗
PubMedDate not supplied

[Bone marrow hematopoietic function and its relation to osteogenesis activity during reparative regeneration in leg lengthening in the dog].

The cellular composition of bone marrow and peripheral blood was studied in different periods of the formation of bone regenerate between the ends of tibia fragments upon their dosed stretching. The intensive regeneration of a hemopoietic rudiment proceeded during the period of active osteogenesis in the elongated bone. A conclusion is drawn that the cellular composition of bone marrow and peripheral blood can be used as indices of the osteogenesis intensity.

Animals↗