Purpose of the study: Variations in patellar height in relation to the trochlea and the joint line can be a cause of pain and instability and limit the range of knee flexion. The Caton and Deschamps index (CDI) was described and validated in a cohort of adult subjects. The purpose of this work was to validate this index and set the reference values in a paediatric population.

Material and methods: Lateral view of the knee were obtained in 300 patients who consulted for minor trauma without ligament or bone injury. Thirty patients, aged 6 to 15 years, were included in each age group (1-year groups). All radiographs were qualified as normal by the radiologist. Two series of measures were made in random order and at an interval of 8 days by two independent observers. The patellar height and the length of the patellar tendon were measured with computer assistance. The interob-server and intraobserver variabilities were determined.

Results: The mean patellar height was 33.39±7.40 mm. The mean length of the patellar tendon was 34.57±67.36 mm. The mean CDI was 1.06±0.21. There was not significant correlation between patient age, height of the patella and length of the patellar tendon. Thus the height of the patella and the length of the patellar tendon increased with age while the CDI was statistically lower in older patients. The height of the patella was identical in the two genders while the patellar tendon was statistically longer in boys. The CDI was statistically higher in boys. Interobserver and intraobserver agreement was excellent.

Discussion: CDI is a simple and reproducible measurement in adults and in children and adolescents. During growth, it is an alternative to the Insall index which has limited reproducibility and the Koshino index which is difficult to use in routine clinical situations. We found a correlation between CDI and children’s age, related to progressive ossification of the patella.

Conclusion: The CDI is a tool which can be used in routine practice to study patellofemoral problems in the paediatric population as long as the physiological values are weighted by age.

Osteosarcoma rarely affects young children. To determine the clinical characteristics and the prognosis of this cancer in children of less than 5 years at diagnosis, we retrospectively analysed medical records of these patients treated in French centers between 1980 and 2007. A centralised histological review was carried out.

Fifteen patients were studied. Long bones were involved in 14 cases. Metastases at diagnosis were observed in 40% of patients. Histologic type was 74% osteoblastic.

In 3 cases (20%) tumours occurred on a particular background (tall constitutional size, treatment with growth hormone and pregnancy induced by clomiphene). One child had a second cancer 13 years after the first diagnosis.

Twelve children received pre-operative chemotherapy including high dose methotrexate: 5 of them had progressive disease; only 36% had good histological response (less than 10% viable cells). Limb salvage surgery was performed in six cases (40%).

Chemotherapy was well tolerated in most patients. A one-year-old child developed a severe late convulsant encephalopathy with lesions of the white substance that could be due to methotrexate despite adjustment of doses to his weight.

The functional recovery of the three analysable children who underwent limb salvage surgery is uneven and shows frequent mechanical or infectious complications (2 to 5 reinterventions per patients).

First complete remission (CR) was obtained in 12 children, six of them relapsed. With a median follow-up of 15 years, six are alive in CR, six died of disease (40%), two were lost to follow-up and one has stable disease with metastasis.

This study shows that osteosarcoma seems to be more aggressive in children under five years of age. Surgical management remains difficult in this population. Prospective studies are still needed to confirm these observations.

Purpose of the study: The posterior paraspinal approach to the lumbar spine was initially described and promoted by Wiltse for posterolateral arthrodesis of the lumbosacral junction in patients with spondylolisthesis. Despite technical improvements proposed by Wiltse, the muscular cleavage is still poorly localized in the sacrospinalis muscle. The purpose of this work was to provide a more accurate anatomic description of this spinal approach and to describe anatomic landmarks to facilitate execution of the procedure.

Material and methods: Fifty anatomic specimens were dissected (27 male and 23 female cadavers); 33 had been embalmed. The anatomy study used a bilateral approach to the spine. The exact anatomic localization of the muscle cleavage was noted. Measures were taken in relation to the mid line of the L4 spinatus process.

Results: In all specimens, the muscle cleavage lay between the multifidus and longissimus heads of the sacrospinalis muscle. A fibrous partition was noted in 88 of the 100 specimens. The mean distance from the mid line to the cleavage line was 4.04 cm (range 2.4–7.0 cm). The surface of the sacrospinalis muscle presented fine perforating arteries and veins in all specimens, directly in line with the cleavage plane. In 12 cases, a major posterior sensorial branch of the L3 nerve running to the skin was identified in the cranial portion of the approach.

Discussion: The muscle cleavage plane appears to be easy to localize for the paraspinal approach to the lumbosacral junction. Opening the aponeurosis of the latissimus dorsi near the mid line enables visualization of the perforating vessels in line with the anatomic cleavage plane of the sacrospinalis muscle. In our experience, this plane is situated on average 4 cm from the mid line. Hemostasis of these vessels is acceptable since the sacrospinalis muscle has a rich supply of anastomosed vessels. Care must be taken to avoid injury to the posterior sensorial branch of the L3 nerve which runs along the plane of the muscle cleavage.

Conclusion: In our opinion, this minimally hemorrhagic approach is perfectly adapted to non-instrumented fusion of the lumbosacral junction, particularly for spondylolisthesis in children and adults. Precise knowledge of the anatomy of this approach is a necessary prerequisite for successful execution.

Purpose: Bone morphogenetic proteins (BMP) are fragile products that must be protected from degradation and released progressively to achieve maximal efficacy. Release of quantities to the order of 10μg are required at ectopic sites in the rat; in humans 50 mg is required to induce new bone formation. Use of high-dose BMP is costly and the risk of overestimulating mesenchymatous cells remains to be determined. Functional dextranes, or DMCBSU, are inert biological derivatives with random substitution of carboxymethyl, benzylamide and sulfonate units. The affinity of these products for other growth factors led us to propose their use as specific carriers of BMP extracted from bovin bone.

Material and methods: Three different gels (CMDB2, OM27, LS8) and the native dextranes from which they are derived (T40, T500) were tested by to determine their capacity to adsorb and release BMP. Uptake and releasing kinetics were studied by fluorimetry using fluoresceine-labelled BMP. CMDB2 and its native dextrane T500, OM27 and LS8 and their native dextrane TT40, and collagen sponge (control) were implanted in the paravertebral grooves of the rat after impregnating the products with different concentrations of BMP (5 μg, 500 ng, 50 ng, 5 ng). The animals were sacrificed at six weeks. The presence of bone tissue was determined by microradiography and histomorphometry.

Results: The more porous gels (OM27 and LS8) adsorbed the greatest quantities of BMP (96.6 and 95.7 ng/ml respectively). Implantation of BMP associated with certain DMBCSU enabled elaboration of bony tissue in an ectopic site for quantities of BMP starting from 50 ng. This bony tissue formation was obtained for collagen sponge controls with doses 100-fold higher (5 μg). Bony tissue obtained with the BMP:DMCBSU combination was endochondral bone presenting cartilaginous lines, followed by mature bony tissue.

Conclusion: This preliminary study demonstrates that by choosing the right specific carrier for bone growth factors, it is possible to considerably reduce the minimal dose required to induce formation of new bone at an ectopic site. Implantations in bone defects of a critical size are under investigation to validate these results in a model closer to the clinical situation.