Mechanical analysis of the healing of different osteotomies fixed externally

Abstract

Under standard conditions the left tibia was osteotomised in nine sheep. The osteotomy was transverse in six, and oblique in three. The osteotomies were fixated using a strain-gauge-monitored unilateral external fixator. The fixation was rigid in three sheep with a transverse osteotomy (group 1) and also in three sheep with an oblique osteotomy (group 2). The fixation was dynamic in three sheep with a transverse osteotomy (group 3) using a roller-bearing mechanism allowing 1 mm of axial displacement. The bone callus stiffness increased progressively with time. One month after osteotomy the load force through the fixator in groups 1 and 2 was more than 20%, whereas the equivalent load force in group 3 was only about 5%.Résumé Avec un fixateur monolatéral instrumenté avec des jauges extensiométriques (strain gauges) on a étudié l'évolution des forces qui passent par le fixateur et la rigidité du cal de fracture chez neuf agneaux ayant trois types d'ostéotomies du tibia et des fixations différentes (I: ostéotomie transversale avec fixation rigide; II: osté-otomie oblique avec fixation rigide; III: ostéotomie transversale avec fixation dynamique. La rigidité du cal de fracture augmente progressivement dans les trois groupes alors que les forces qui passent par le fixateur diminuent. Après un mois, chez tous les animaux ayant un traitement rigide (groupe I et II) les forces qui passent par le fixateur sont supérieures à 20%, alors que dans le groupe III, à la même période, les forces moment sont approximativement de 5%.

Influence of Gender and Fixation Stability on Bone Defect Healing in Middle-aged Rats: A Pilot Study

“…The local mechanical environment also influences healing outcome [1,12,15,19,27]. Initial instability can delay bone healing or lead to nonunions as a result of rupturing of the bridging tissue, including the nutrimental blood vessels [10,14,15,17].…”

“…Initial instability can delay bone healing or lead to nonunions as a result of rupturing of the bridging tissue, including the nutrimental blood vessels [10,14,15,17]. On the other hand, if mechanical stimuli are completely absent, bone healing may also be delayed [6,10].…”

Mechanical behavior of an osteotomized mandible with distraction orthodontic devices

“…The callus, obtained by cutting the mandible with two planes P 1 and P 2 parallel to the middle sagittal plane, is modeled as a ''soft region'' of very low Young's modulus. Young's modulus is estimated from results reported in Mora and Forriol (2000) that measured at different time intervals the equivalent callus stiffness (N/mm) of an osteotomized sheep bone then re-joined with external fixators. Under tensile stresses, the equivalent stiffness K of the bone callus which formed between osteotomized bone segments can be obtained from the well-known engineering relationship:…”

Long‐term effects of saw osteotomy versus random fracturing on bone healing and remodeling in a sheep tibia model

“…15 Several methods of osteotomy have already been evaluated with an animal model. [16][17][18][19] However, these studies always assumed that bone healing is identical to that occuring after common fracturing over a specified period of time.To our knowledge, there have been no studies evaluating differences between partial osteotomy and a neighboring partial fracture. The present study was therefore designed to test the hypothesis of whether differences in bone healing between saw osteotomy and random fracturing, in terms of tissue necrosis, vascularization, and remodeling, are apparent under long-term observation.…”

“…15 Several methods of osteotomy have already been evaluated with an animal model. [16][17][18][19] However, these studies always assumed that bone healing is identical to that occuring after common fracturing over a specified period of time.…”