This study evaluated the histological changes in muscle tissue after limb lengthening in skeletally mature and immature rabbits and assessed the most vulnerable level of striated muscle. Twenty-three male domestic white rabbits, divided into six groups, were operated on and different lengthening protocols were used in the mature and immature rabbits. The histopathological changes were analysed by a semi-quantitative method according to the scoring system of Lee et al. (Acta Orthop Scand 64(6): 688-692, 1993). After the evaluation of the five main degenerative parameters (muscle atrophy, muscle nuclei internalisation, degeneration of the muscle fibre, perimysial and endomysial fibrosis, haematomas), it is evident that the adults lengthened at a rate of 1.6 mm/day showed more degenerative changes than those lengthened at 0.8 mm/day. The adult 1.6 mm/day lengthened group presented significantly higher damage in the muscle and lower regenerative signs compared with the young 1.6 mm/day lengthened group, according to the summarised degenerative scores.Résumé Objectif: Cette étude a pour but d'évaluer les changements histologiques des muscles après allongement squelettique chez des lapines matures ou immatures. Elle permet d'évaluer quel est le niveau de lésion des muscles striés. Matériel et méthode: 23 lapins mâles domestiques blancs ont été divisés en six groupes et traités avec différents protocoles d'allongements.. Les changements histologiques ont été analysés avec une méthode semi quantitative utilisant le score de LEE et collaborateurs. Résultats et conclusion: l'évaluation des cinq principaux paramètres de dégénérescence (atrophie musculaire, noyau musculaire, internalisation, dégénérescence des fibres musculaires, fibrose du périmysium et de l'endomysium, hématome). Il apparaît évident que l'allongement chez l'adulte à un rythme de 1,6 mm par jour entraîne plus de lésions dégénératives que les sujets allongés au rythme de 0,8 mm par jour. Le groupe de lapins adultes avec allongement de 1,6 mm par jour présente des lésions hautement significatives du muscle, avec des signes de régénération musculaire moins importants que ceux du groupe de lapins plus immatures allongés au même rythme, ceci en utilisant des scores identiques.
The purpose of this study was to establish a nomogram in order to predict limb length discrepancies in children with unilateral fibular hemimelia more accurately. In 31 children with unilateral fibular hemimelia the femoraltibial length and skeletal age were determined an average of seven times per case by sequential radiographs during growth. From the data, a skeletal age nomogram was developed which shows a steeply declining mean skeletal age pattern in unilateral fibular hemimelia (the slope in girls was −0.59 and in boys −0.64). This nomogram crosses the normal mean skeletal age line of the Moseley straight-line graph at 10.5 years in girls and at 12 years in boys, and continues to decline until maturity. The results demonstrate an abnormal skeletal maturation process in patients with unilateral fibular hemimelia. The consistently declining steep skeletal age nomogram in unilateral fibular hemimelia makes prediction of skeletal maturity and limb length discrepancy inaccurate by the standard predictive methods particularly when using early skeletal ages. The skeletal age nomogram from our data determines skeletal maturation in children with unilateral fibular hemimelia more accurately, and allows a correct prediction of limb length discrepancy.
The present study evaluated the radiological changes in normal and dynamized callus after limb lengthening in New Zealand White rabbits. The aims of the study were to create a lengthening device that allows axial controlled manual dynamization and to examine the effect of the maximal amount of dynamization on the healing, lengthened callus. 10 male domestic white rabbits were divided into two groups (normal distraction group (NDG) and dynamized distraction group (DDG)). Osteotomy was followed by distraction at the same rate and total length in both groups, but in the dynamized distraction group 1 mm manual dynamization was performed for ten minutes three times a day prior to lengthening. Callus formation and lengthening were analysed on the X-ray pictures and on the three-dimensional CT image respectively. Neither malposition of the pins nor maluninon were found during or after the distraction period. No signifi cant difference was found in the amount of the callus between the NDG and DDG. A lengthening device was created that allows axial controlled manual dynamization and prevents instability in the other two axes and our results showed that this large amount of dynamization did not decrease the formation and quality of the callus.
The present study evaluated the histological changes in the muscle tissue after limb lengthening in skeletally immature rabbits and assessed the effect of different lengthening rates on the regeneration and degeneration properties of striated muscle. Thirteen different lengthening protocols were applied on a total of 16 male domestic white rabbits divided into four groups. The histopathological changes were analysed by a semiquantitative method according to the scoring system of Lee et al. (1993). After evaluation of the five main degenerative parameters (muscle atrophy, internalisation of muscle nuclei, degeneration of the muscle fibre, perimysial and endomysial fibrosis, haematomas), it is evident that rabbits subjected to limb lengthening at a rate of 3.2 mm/day showed more degenerative changes than those limb-lengthened at 0.8 or 1.6 mm/day. Our study showed that the regenerative mechanisms were not endless. If the daily lengthening rate reached the 3.2 mm/day limit, the regenerating ability of the muscle decreased, and signs of degeneration increased significantly.
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