Jean Legaye

Conséquences défavorables sur l'équilibre sagittal du rachis du système de neutralisation dynamique.

PURPOSE OF THE STUDY: The dynamic neutralization system (Dynesis) has been proposed for the treatment of symptomatic lumbar discopathy. This system preserves the mobility of the instrumented vertebral segment and restores discal height by posterior distraction on pedicular screws, stabilization being ensured by compression on a spacer. The potential kyphosing effect of this system and the impact on sagittal morphology of the spine were analyzed. MATERIAL AND METHODS: Twenty-six patients were studied. Lateral x-rays of the lumbar spine in the upright position were obtained before and after the surgical procedure and at mean 9.5 +/- 3.3 months follow-up. Comparisons were made between the pre- and postoperative presentation with measurement of the pelvic and spinal sagittal parameters described by Duval-Beaupere: inclination of the pelvic segment on the sacrum, lordosis, and disc wedge angles at each level (particularly the instrumented levels). Sagittal morphology was assessed pre- and postoperatively. RESULTS: Mean kyphosing effect was 6 +/- 1.4 degrees, induced by the posterior distraction system. This accentuated the initial lumbar hypolordosis related to the degenerative disease. Comparison of the pre- and postoperative films revealed four types of sagittal reaction of the lumbopelvic segment: no modification (type A), significant loss of lordosis without change at the pelvis level (type B) or with compensatory pelvic retroversion (type C), accentuation of the lordosis with pelvic anteversion (type D). CONCLUSION: The dynamic neutralization system (Dynesis) can stabilize degenerative discopathy and protect the adjacent levels. Posterior distraction perturbs the initial hypokyphosis and can lead to pelvic compensation to achieve better dynamic balance. This loss of lordosis is however a cause of excessive mechanical stress on the lumbar structures and can lead to long-term degradation. Future developments of this dynamic system should take into account the essential factor of sagittal balance.

Contributing factors for osteogenesis in children's limb lengthening

A progressive bone lengthening procedure according to the Wagner and Ilizarov technique and our own protocol was performed on 24 children (32 bones). Wagners (transverse midshaft osteotomy, intraoperative lengthening of 1 cm and postoperative distraction of 1 mm/day) led to a marked reduction in osteogenic capacities. Patients operated on according to the Ilizarov technique had osteogenic reactions in the medullary cavity and on the posterior aspect of bone segments. Our own method, which included bone decortication, 5-7 days of neutral fixation without distraction, led to massive bone production in the medullary canal and around the bone segments. Rigid osseous bridging was present as early as 3 months after surgery. Neither the type of external fixator nor the location or shape of osteotomy had any specific influence on this massive bone reaction. Osteogenesis in limb lengthening is thus closely related to surgical management.

Kyste arthro-synovial de hanche sur prothèse totale à couple de friction céramique-céramique

An inguinal arthrosynovial cyst of the hip joint developed after total hip arthroplasty leading to compression of the femoral vein. This complication occurred after implantation of a non-cemented prosthesis with a ceramic-on-ceramic interface inserted in a polyethylene sandwich. Multiple foreign bodies composed of both ceramic and polyethylene particles were visualized microscopically. Later, rupture of the joint interface required implant replacement. This cyst was a precursor sign of a deteriorating prosthesis surface.

Neurologic Hip Disorders Treated By Femoral Shortening and Lesser Trochanter Detachment

In a group of 40 children with cerebral palsy (CP), myelomeningocele, or sequelae of previous tenotomy and neurotomy, a specific surgical approach was used to correct various type of hip disorders: migrating hip, subluxated or luxated hip, compressed hip, and wind-blown hip, especially in quadriplegia. Osteotomy is performed at the intertrochanteric area, where a segment of femur (3-5 cm) is removed and the lesser trochanter is released, allowing the psoas muscle to reinsert in a more proximal position. Based on the concept of imbalance between predetermined bone growth and passive adaptation of muscles, we postulated in 1982 that a reduction in bone length should have an effect on surrounding muscles, allowing them the possibility of working in better anatomic conditions. With our procedure, we obtain major release of muscle tension around the hip-release of hamstring, psoas, and tensor of fascia lata-and consequently a wide range of passive motion of the hips as well as the knees. Long-lasting effects are preserved only by use of regular splinting for a prolonged time. In hip luxation, reduction can be obtained by this extraarticular approach, without need to open the joint. A pelvic procedure is performed only when the acetabulum shows marked changes. In five children with CP, the procedure was combined with shortening of the patellar tendon to reactivate the extensor mechanism of the knees. We consider this specific approach a safe procedure that leaves the neural anatomy undisturbed and allows early ambulation, usually at 4 weeks. It may be used as a salvage procedure and as the initial treatment step for various neurologic hip disorders.