Les allongements des membres selon la technique d'Ilizarov présentent encore des problèmes dont la survenue possible de déviation axiale lors de l'allongement, la lenteur de consolidation du régénérat et le risque de fracture après l'ablation du fixateur.

L'association de l'allongement selon Ilizarov et d'un embrochage centromédullaire élastique stable (ECMES), dont les avantages sont connus en traumatologie pédiatrique, a pour objectif de pallier ces complications.

Dans une première partie, un travail expérimental chez le chien a permis d'étudier l'allongement de 11 tibias : l'intervention chirurgicale consistait en la pose du fixateur externe d'Ilizarov, l'ostéotomie respectant le périoste et la vascularisation centromédullaire, et un embrochage centromédullaire élastique stable. L'allongement a duré 28 jours au rythme initial de 1 mm/jour, la durée de la période de fixation était de 30 jours. Dans 7 cas sur 11, il a été nécessaire d'accélérer le rythme d'allongement en raison de la survenue d'un régénérat précoce important. Tous les cas ont rapidement consolidé sans complication.

Dans une 2^e partie clinique, 14 patients ont bénéficié de cette association chirurgicale lors du traitement d'une inégalité de longueur d'origine acquise ou congénitale. Dans tous les cas, l'ossification du régénérat a été plus courte que dans les séries d'Ilizarov sans ECMES, avec un index de consolidation moyen de 18,6 jours par centimètre (ET = 6,2). Le fixateur externe a pu être enlevé plus précocement. Aucune complication n'a été observée, en particulier aucun cas d'infection osseuse.

Bone lengthening with the Ilizarov technique gives good results but certain disadvantages are common: possible axial deviation during lengthening, long time to bone union, risk of fracture after removal of the external fixator. Associating the Ilizarov technique with elastic stable intramedullary nailing (ESIN) commonly used in traumatoloy has to be evaluated. We conducted an experimental study and report results of the first clinical application.

Eleven lengthenings of the tibia were conducted in dogs aged 1 to 4 years using an Ilizarov external fixator associated with ESIN. Lengthening started on day 1 and continued for 28 days. X-rays were obtained every week during lengthening, then at 15 and 30 days during the fixation period and 30 days after removal of the fixator. In two cases, arteriography was performed. In a pilot clinical trial, fourteen patients (8 males, 6 females) were treated with this method (1 humerus, 1 forearm, 7 femurs, 5 tibias). Mean patient age was 14 years.

In the experimental study, the x-rays showed rapid ossification of the regenerate which led to increased tibia length in 7 cases from 1.25 to 2 mm/day. Total bone union was observed in four dogs during the lengthening period. At day 15 of the fixation period, all tibia had fused with a good quality cortical bone and healing of the growth part of the regenerate. In three dogs, the external fixator was removed at day 15 of fixation and weight-bearing was total with the ESIN in place. No axial deviation and no skin problems were observed. The medullary artery was seen on the two arteriograms. In the clinical trial, bone union of the regenerate appeared earlier than in the Ilizarov series. The regenerate always displayed good density on the x-rays, proving intense bone activity. In three patients, the lengthening rate was increased to avoid premature bone fusion. The endosteal bone regenerate was obvious. Mean healing index was 18.6 days/cm (SD = 6.2). Weight-bearing was allowed at six weeks. The desired correction was achieved in all patients and no complications were related to ESIN.

Bone lengthening may be obtained with an intramedullary locking nail which avoids the use of an external fixator but also destroys the endomedullary circulation. Our experimental and clinical study shows that use of an ESIN does not inhibit the endosteal regenerate and seems to improve new bone formation. In many patients, the lengthening rate had to be increased to avoid premature bone fusion. When used in optimal conditions, ESIN can stimulate new endosteal and periosteal bone formation. In addition, ESIN increases shaft stability avoiding the risk of axial deviation. ESIN plays an additional role of stabilization after early removal of the external fixation.