Purpose of the study: Attempts to control growth of the spine without provoking epiphysiodesis is a promising area of investigation. The purpose of our experimentation was to achieve localized interruption of vertebral body growth without damaging the adjacent disc and ligament structures.

Material and methods: Two Yucatan micropigs weighing 7 and 9 kg were used for this study. Before initiating the experiment, a complete imaging work-up (x-ray, computed tomography, magnetic resonance imaging) of the spine of the two pigs was obtained. The animals were anesthetized for thoracotomy and a 810 nm 30W laser diode (Diomed Ltd) was implanted in the superolateral part of nine vertebral bodies (3 mm under the cartilage endplate and 3 mm in depth) in order to apply a certain quantity of heat. The nine vertebrae were divided into three groups of three vertebrae. Each group received 2W for 200, 300, or 400s (groups 1, 2 and 3 repectively). The temperature generated by the thermal delivery was recorded in the growth cartilage and in the disc using thermal probes. A complete imaging series of the spine was again obtained four months later, before sacrifice. The results presented correspond to the CT-scan findings used to analyze the effect on vertebral growth and to the MRI findings used to check for discal injury. Each vertebral level was sampled for a histological examination and (in the second part of the study) a biomechanical analysis was undertaken.

Results: Among the 18 vertebral levels studied (two micropigs), 11 levels exhibited localized interruption of growth without any alteration of the adjacent discs. We were unable to observe any significant correlation between the temperature recorded in the disc and the discal structure observed at sacrifice, although above 52°C, there appeared to be a greater risk of definitive discal damage. As disc growth can be controlled (as demonstrated in this study) without damaging the adjacent disc (which will require further study to demonstrate) is would be possible to use this technique as an alternative to treatment by corset for progressive idiopathic scoliosis in growing children.

Purpose of the study: Assessment of limb reconstruction results using vascularized fibular grafts after bony resection for malignant tumors in children.

Material and methods: Thirty children (9 girls and 21 boys)underwent surgery between 1993 and 2000. Mean age was 11 years. Tumor localizations were: femur (n=17), tibia (n=6), humerus (n=5), radius (n=1) and distal ulna (n=1). Mean length of bone resection was 16 cm (range 10–26 cm). For 22 children, the adjacent epiphysis was preserved. For the eight others, fusion was also performed. Two surgical teams operated sequentially: the first team performed the tumor resection and the second (an orthopedist for the osteosynthesis and a plastician for the vascularized fibular transfer) the limb reconstruction. Radiographic and clinical assessment was completed with bone scintigraphy. The index of graft hypertrophy was determined with the De Boer and Wood method. Functional outcome was assessed with Enneking criteria.

Results: Mean follow-up was 51 months (range 2 – 9 years). Early amputation was necessary for two children due to local oncological complications. One patient died of pulmonary metastasis eight months after limb reconstruction. Among the 27 other patients, primary healing was achieved in 22. In the five with primary nonunion, bone scintigraphy showed objective signs of a lack of blood supply to the graft. Secondary union was achieved with a complementary autologous bone graft in four cases. All cases of stress fracture healed with orthopedic treatment. For the 22 patients with primary union, the graft hypetrophy was 22–190% (mean 61%). For the five patients without bone vascularization on the scintigraphy, the fibular graft failed to hypertrophy. Functional outcome was satisfactory. The modified Enneking score (30 point scale) was 26 (range 19–30 points).

Discussion: Limb reconstruction results are directly related to good patency of vascular anastomoses. Postoperative bone scintigraphy is useful to determine blood supply to the graft and to establish the final prognosis. In the case of vascular failure, an autologous bone graft can be proposed early to enable union. Close collaboration between the plastic surgery and the orthopedic team is the key to successful limb reconstruction with a vascularized fibular graft.

Purpose of the study: In the growing pig, we have been able to achieve localized control of vertebral body growth by selective destruction ofhte physis using the thermal effect of a laser probe (first part of the study). The purpose of the second part of the study was to evaluate the mechanical effects in terms of 1) intersomatic disc mobility, and 2) bony resistance of the vertebral body and risk of fracture.

Material and methods: Thoracotomy was performed on two Yucatan micropigs (group A); a 510 nm 30W diode laser delivered heat applied to nine vertebral bodies. Four months later, the micropigs were sacrificed. Two normal micropigs (group B) served as controls. The specimens were dissected to the intersomatic disc-ligament complex. Three-level vertebral assemblies were thus obtained for mobility tests (flexion-extension, lateral inclination, right-left rotation). Destruction tests were pursued to fracture. Tests were performed with a Zebris 3D motion analyzer. Computed tomography images and histological findings were also assessed.

Results: Motion: In group A, when the discal space appeared normal on the specimen, no difference was noted in motion in comparison with group B. Conversely, when imaging demonstrated discal injury, joint stiffness was noted. The destruction tests showed that in group A specimens the fracture did not occur at the zone of lytic bone destruction caused by the heat delivery. Fractures observed were similar in the two groups, including epiphyseal detachements and sagittal fractures of the vertebral bodies.

Discussion: Applying laser-delivered heat to the vertebrae in micropigs enabled partial destruction of the physis without injuring the intervertebral disc. Heat delivery induced a modification in vertebral growth. When imaging showed an intact neighboring intervertebral disc, mechanical tests showed normal mobility and resistance. Bone resistance was not diminished. This result is important to consider for the treatment of vertebral osteoid osteomas with laser.

Conclusion: Laser application to vertebral bone is a reproducible method which can stop growth of the minipig vertebral bodies without injuring the intervertebral disc and without reducing bone resistance.

Purpose of the study: In spina bifida, independently of limb paralysis, spinal deformation can cause significant static disorders (scoliosis, kyphosis, or hyperlordosis) which in turn cause significant disability. These deformations generally develop during growth. We wanted to determine the predictive value of a clinical classification based on the neurological examination at five years for risk of spinal deformation.

Material: This retrospective study included 163 patients. Groups were defined on the basis of motor function determined by the neurological examination at five years: group I: L5 or below (all patients in this group had motor deficit leaving at least one L5 segment intact); group II: L3–L4; group III: L1–L2; group IV: T12 and above.

Results: Results showed that group I was a factor predictive of an absence of future spinal deformation. Groups III and IV were predictive of presence of a future spinal deformation. Group IV was predictive of future kyphosis.

Discussion: It is well known that the higher the neurological lesion in spina bifida, the higher the rate of spinal deformation. No work has however set the limits nor provided predictive rules useful in clinical practice. Our work demonstrated that this classification based on the motor function established by neurological examination at five years can predict which children have a risk of developing a spinal deformation and thus enabling early detection and treatment.

Conclusion: This neurological classification can be used as a clinical tool for the prognostic evaluation of spina bifida.

Purpose: The purpose of this work was to present the long-term outcome after resection of thoraco-lumbar, lumbar, or lumbosacral hemivertebrae in 69 children.

Material and methods: Sixty-nine children (35 girls and 34 boys) underwent surgery at a mean age of 3 years (range 1 year – 10 years 6 months). Mean follow-up was 6 years (range 6 months – 18 years). Resections involved thoracolumbar (n=20), lumbar (n=34), and lumbosacral (n=15) hemivertebrae. Congenital vertebral and visceral malformations were present in 32% and 41% of the children respectively. Ten patients had an underlying neurological malformation.

A single operation was performed in 60 patients using a combined anterior and posterior approach and convex posterior CD baby instrumentation. Nine patients underwent two operations one week apart. All patients wore a corset brace for six months.

Results: Structure curvature: the mean Cobb angle was 35° preoperatively, 16° postoperatively, and 15° at last follow-up.

Compensating curvature: the mean Cobbe angle was 21° preoperatively and 12° at last follow-up. Complications: partial deficit of the anterior tibialis (n=1), nonunion (n=3), infection (n=1), disassembly (n=3), valgum tibia at the site of the fibular graft harvesting (n=1).

Discussion: At these spinal levels, hemivertebral resection appears to be the most appropriate technique for children aged less than three years as long as there are no clear signs of progressive curvature.

Purpose: Reconstruction after resection of malignant bone tumours remains a major challenge. Free vascularised fibular grafts may be a useful alternative in this indication.

Material: Thirty children (nine girls, twenty-one boys) were treated between 1993 and 2000. Mean age was eleven years. Tumour histology was: osteogenic osteo-sarcoma (n=20), Ewing tumour (n=5), justacortical osteosarcoma (n=3), synovialosarcoma (n=1), and chondrosarcoma (n=1). Tumours were located in the femur (n=17), the tibia (n=6), the humerus (n=5), the radius (n=1), and the distal fibular (n=1). The length of resection varied from 100 mm to 260 mm (mean 160 mm). Internal fixation was used in 27 cases and external fixation in three. The adjacent epiphysis was preserved in 22 cases and initial arthrodesis was performed in eight.

Method: Patients were followed clinically and radiographically. A bone scintigram was obtained in all patients at least once during the postoperative period. Radiological assessment was based on the hypertrophy index of the graft using the method described by DeBoer and Wood. Functional outcome was assessed using the Enneking criteria.

Results: Mean follow-up was 51 months (range 2 – 9 years). Early amputation was required in two patients due to local ocological complications. One patient died at eight months follow-up due to lung metastasis. Among the remaining 27 patients, primary bone healing was achieved in 22. The five other patients exhibited clear signs of non-vascularisation. Successful healing was achieved in four of these patients after a complementary autologous graft. All cases of stress fracture healed after simple immobilisation.

The twenty-two patients who achieved primary bone healing developed a hypertrophic graft (mean 61%, range 22 – 190%). Graft hypertrophy was not observed in the five cases requiring a secondary graft after the scintigram demonstrated lack of vascularisation. Hypertrophy of the vascularised fibular graft was more marked for lower limb reconstructions than for upper limb reconstructions..

Functional outcome was satisfactory in all cases. On the 30-point Enneking scale as modified, our patients achieved a mean 26 points (range 19 – 30).

Discussion: Outcome was directly related to patency of the vascular anastomoses. Bone scintigraphy, performed one month after reconstruction surgery, was an important element for assessing prognosis. In case of unsuccessful vascularisation, a complementary cortico-cancellous graft should be used. Early weight-bearing is advisable using adequate protective devices. Dynamic osteosynthesis systems should be helpful in improving graft hypertrophy.

Purpose of the study: Advances in chemotherapy protocols over the last 20 years have considerably improved the prognosis and functional outcome in patients with osteogenic sarcoma. We report here the results of a cooperative study conducted under the auspices of the French Society of Pediatric Oncology (SFOP). Twenty-nine oncology centers participated in this retrospective national multicentric study.

Materials and methods: The study included 15 .3 patients with osteogenic sarcoma of the limb who were treated by the OS87 protocol with conservative surgery between 1987 and 1994. The OS87 protocol consisted in conservative or nonconservative surgery combined with pre- and postoperative chemotherapy. The following inclusion criteria were used: age under 20 years, tumor localization in a limb (pelvis and spine excluded), no metastasis at diagnosis, biopsy proven osteogenic sarcoma.

Results: Mean age at diagnosis was 13 years. The knee localization predominated (80 p. 100). 82.5 p. 100 of the patients had grade IIB disease (Enneking classification). For the 187 patients included in the protocol surgery was nonconservative in 20 p. 100 of the cases and conservative in 80 p. 100. The choice of the surgical technique (arthroplasty, allograft, autograft, resection without reconstruction) depended on the patient’s age and school situation. Data analyzed here concerned only those patients who had conservative treatment. Mean follow-up was 64 months. The actuarial survival curve plateaued at 71 p. 100 at more than 6 years. Early and late complications were numerous and variable (mechanical, infectious, local recurrence). Secondary amputation was required in 10 p. 100 of the patients. The overall functional outcome of the preserved limbs was nevertheless good with rapid restoration of self-sufficiency despite major surgery and a high number of reoperations (about 65 p. 100 of cases).

Discussion: In light of the frequency and the seriousness of the complications, these results are modest. Patients and family should be advised of the risk, particularly the risk of secondary amputation which may be required early due to contaminated excision or at mid term due to major non-cancerological complications. As survival has been improved, functional capacity must be preserved for several years. This orients surgery towards more “biological” reconstruction which can provide greater longevity than arthroplasty.