Introduction

Since 2001 we use the flexible intramedullary nailing (FIN) in bone lengthening in children. This study estimates results of EF+FIN association considering the duration of external fixation and complications.

Purpose of the study: There is a link between complications and duration of instrumentation. Since 2001, we have associated circular external fixation (EF) and stable elastic centromedullary nailing (SECMN) to shorten the duration of the external fixation in bone lengthening in children. This study was designed to assess the results of the EF+SECMN for this indication.

Material and methods: From 2001 to 2009, progressive bone lengthening was performed in 250 children aged 3 to 16 years. There were 295 progressive lengthening procedures involving 339 segments. Indications were congenital (n=163) and acquired (n=87) length discrepancy. In group I (195 lengthenings, 222 segments), the Ilizarov EF was used alone. In group II, the Ilizarov (n=92, 108 segments) or the TSF (n=8, 9 segments) EF was associated with SECMN. After insertion of the EF, the centromedullary nails were introduced after the osteotomies. The healing date was the date the EF was removed; the nails were left in place to protect the bone. The healing index was calculated from duration of the EF (in days) divided by lengthening (in cm).

Results: Use of SECMN shortens the duration of EF irrespective of the aetiology, the segment, the lengthening method (mono- or polysegmental, mono- or poly-focal), with a statistically significant difference between the two groups (gain of 6 to 12 d/cm). In group I, deformities or fractures of the regenerated bone after removal of the EF occurred in 21 cases (10.77%), deep infections in 4 (2.05%), osetomyelitis in 2 (1.03%). In group II, the only complications were late healing (1%) and 10° angulation at the lengthening site (1%). The centromedullary nails migrated in eight patients, with no impact on the lengthening results.

Discussion: With SECMN, the lengthening procedure is achieved with an elastic but resistant system. It is hypothesised that this system stimulates osteogenesis since the healing index is improved. SECMN does not prevent progressive correction of shaft or diaphyseal deviations. By shortening the duration of external fixation, this method had a great impact on reducing serious complications such as fractures and deep infections.

Conclusion: SECMN can considerably reduce the duration of external fixation during bone lengthening procedures in children and reduce (or eliminate) most of the serious complications.

Purpose of the study: A population of 154 patients was studied to determine the advantages of continuous lengthening for congenital lower limb length discrepancy (LLLD).

Material and methods: In a first series, we analyzed 80 progressive lengthenings using the standard rhythm (1 mm daily, 4 lenghtenings per day). In a second series (74 lengthenings) a high-frequency rhythm was used (1 mm daily, 60 lengthenings per day). Mean patient age was 10.3 years. Bone regeneration was not stimulated (either by extemporaneous compression or stable elastic centromedullary nailing) in this population. The automatic lengthening fixator was composed of the two standard pieces of the Ilizarov system and complementary blocks with self-propelled traction rods. Besides simplifying the lengthening procedure, these rods allowed high-frequency correction of associated deformities.

Results: Femoral gain was 52 mm on average. For the tibia, the gain was 48 mm on average. For ordinary monosegmentary lengthenings, the healing index was 27.6 d/cm for the femur and 36.0 d/cm for the tibia. For multisegmentary lengthenings with the standard rhythm, the overall healing index was 20.3 d/cm. For patients with high-frequency lengthening, time to healing was shorter. The radiological findings showed the presence of significant bone regeneration which was never inhibited. For monosegmentary lengthenings, the healing index was 22.9 d/cm for the femur and 27.1 d/cm for the tibia. For the multisegmentary high-frequency lengthenings, the overall healing index was 14.7 d/cm. The difference between standard and high-frequency lengthening was significant. In the first series, motion of the adjacent joints was recovered within 12 to 18 months after removal of the fixator. The patients remained in the reclining position during the high-frequency lengthenings and very satisfactory results (complete recovery of joint motion) were obtained 12 months after removing the fixator. In addition, in the second series, there was no impact on the spontaneous growth of the lengthened segments.

Discussion and conclusion: Congenital LLLD is generally more difficult to treat than acquired conditions (Damsin et al., Grill et al., Glorion Ch.). The rate of complications remains significant, particularly concerning healing complications and stiffness in the adjacent joints. Our clinical results prove that high-frequency lengthening provides optimal conditions for tissue regeneration. For children with congenital LLLD, continuous lengthening shortens the delay to healing and avoids stiffness in the adjacent joints.

Purpose: The purpose of this study was to evaluate centromedullary pinning for bone lengthening. We studied an animal model to discover the details of bone regeneration and assess the advantages of the technique. We present our early clinical results.

Material and methods: Progressive lengthenings of the tibia by centromedullary pinning were performed in eleven dogs. Distraction began on day 5 and lasted 28 days. Arteriograms were obtained after sacrifice.We also analysed 17 cases of limb lengthening in patients: one arm, two forearms, nine femurs, five tibias. Mean patient age was 14 years. Mean gain in bone length was 6.2 cm.

Results: The experimental work demonstrated that intensive bone regeneration requires faster distraction. Early bone union was observed in four dogs. Bone healing was complete at about 15 days in all dogs. The centromedullary pins were left in place in three dogs after removing the external fixator. There was no secondary deformation. The arteriogram showed that the nourishing artery was not ruptured. In our patients, delay to healing was shorter. The radiograms demonstrated intensive bone regeneration. Endosteal regeneration was significant and was never inhibited. Significant periosteal reaction was observed. The planned gain in length was achieved in all patients. We did not have any complications.

Discussion: Bone lengthening methods using a centromedullary nail provide absolute stability while avoiding external fixation but at the cost of complete destruction of the centromedullary vascular supply. Our animal experiments and clinical experience prove that elastic centromedullary pins do not inhibit endosteal regeneration but, on the contrary, partial destruction of the marrow with intact vascularisation stimulates bone regeneration. For bone lengthenings, centromedullary pinning is the only method of internal fixation allowing optimal conditions for bone regneration.

Conclusion: The progressive distraction of the elastic centromedullary pin during the lengthening period stimulates the regenerative processes. The biological effect of the vascular “displacement” from the centre to the periphery of the bone fragments leads to significant periosteal reaction. Elastic centromedullary pinning adds stability to the bone fragments. Associating the two methods allows removal of the external fixator leaving the centromedullary pins in place. By strengthening the regenerated bone, the pins provide a certain degree of additional stability.