Purpose of the study: Little work has been reported on the effects of BMP on bone healing after distraction and the data available in the literature are contradictory. The type of BMP as well as the optimal dose remain to be defined. We present the results and complications linked with the use of different doses of rhBMP-2 in a model of osteogenesis in distraction.

Material and methods: Fifteen subadult New Zealand rabbits were selected at random and divided into three groups. On day 0, a mediodiaphyseal tibial osteotomy was cut and an M103 fixation implanted. In group I (5 rabbits), 750μg of rhBMP-2 with a type I collagen sponge (Inductos, Medtronic) were deposited on the osteotomy site. In group II (5 rabbits), 350 μg were deposited on the collagen sponge and in group III (controls, 5 rabbits), nothing was deposited. After the 7-day latency period, distraction was conducted for 21 days (0.5 mm(12hr). At the second week of distraction, the callus was analysed on the x-rays and ultrasounds and a weekly absorptiometry was obtained. The animals were sacrificed three weeks after healing was confirmed.

Results: Quantitative radiographic assay showed significantly superior grading (Kirker-Head) in groups I and II (p< 0.05) compared with group III. The qualitative analysis showed premature healing of the regenerate preventing completion of the distraction (pin distortion) for 3/5 rabbits in group I and 1/5 in group II. Bone mineral content was superior in groups I and II in all times studied than in group III (p< 0.05). The difference was also significant between groups I and II (p=0.0087) demonstrating an expected dose effect.

Discussion: Premature healing was achieved for the majority of animals in group I, underlining the importance of the dose of BMP used to stimulate bone healing after callotasis. The undesirable effect thus obtained should be taken into account in the clinical context. A dose of 100 μg/kg (350 μg, group III) appears to suffice in this model and defines the upper dose limit. Differed application of the compound (after distraction) should be useful and should be studied.

Conclusion: The dose of rhBMP-2 used to stimulate bone healing is an essential parameter that should be defined for each experimental model. The dose effect of rhBMP-2 is demonstrated in this particular model.

Introduction: The aim of this study was to identify the pattern of symptoms in patients presenting with synovial sarcoma, examine how these corresponded to the symptoms outlined by the NICE guidelines on the rapid referral of patients with a suspected sarcoma and spot factors that led to long delays in diagnosis.

Methods: Early symptoms and the results of clinical and radiological investigation were reviewed along with the presumed diagnoses that had been made for 35 children. The total duration of symptoms was separated into patient delay and doctor delay.

Results: Using the four clinical findings suggestive of sarcoma according to the NICE guidance, only half of the patients had one or more of them at the time of initial symptoms. The most common presentation was a painless mass (n=16), and in 10 children there was no mass identified. Seven patients had an inexplicable joint contracture, many having been extensively investigated unsuccessfully. The mean duration of symptoms before the diagnosis was made was 98 weeks (range 2 to 364). The mean number of doctors seen prior to referral was 3 (range 1–6) and for 15 patients the diagnosis was obtained after inadvertent excision. The factors associated with long duration of symptoms before diagnosis were knee and elbow location (p=0.0047) or periarticular location (p=0.01), absence of lump (p=0.016) or painful mass as early symptom (p=0.04), the presence of calcifications on x-rays (p=0.01) and a fixed joint contracture (p=0.0003).

We could not show that delay in diagnosis led to a worse prognosis.

Discussion: This paper highlights the sometimes bizarre symptoms associated with synovial sarcoma and hopefully this will increase awareness of the condition among relevant sections of the medical profession and help to reduce the delay in diagnosing these cases.

Purpose of the study: Chondroblastoma is a rare benign cartilage tumor usually observed in secondary ossification centers of long bone in subjects aged 10 to 20 years. We report a multicentric series of 63 cases of chondro-blastoma in children and attempt to identify particular pediatric epidemiological features and identify factors of risk of recurrence.

Material and methods: Clinical data an pre and postoperative imaging were analyzed as well as the histological findings reported by one observer. Files were collected from ten pediatric orthopedic units in France (two in Lyon, three in Paris, Rennes, Strasbourg, Toulouse, Saint-Etienne, Nice). Data were stored in a single database. The series included 35 boys, and 29 girls (sex ratio 1.25=. Mean age at diagnosis was 12 years (18 months to 17 years), 13 years for boys and 11 years for girls. Tumors were located in the epiphysis of the proximal tibia (n=17), the proximal femur (n=16), proximal the humerus (n=16), the distal femur (n=4), tarsal bones (n=4), the distal tibia (n=2), the fibula (n=2), the pelvis (n=1) and the distal radius (n=1). Preoperatively, the Springfield classification was: latent (n=14), active (n=36), aggressive (n=8); five tumors could not be classified. Treatment consisted in curettage-graft (n=40), curettage alone (n=17), curettage and cement filling (n=3), en bloc resection with reconstruction (n=3). Adjuvant alcoholization was used in one case. The histological study searched for an aneurysmal component within the tumor. Four patients were lost to follow-up and 59 patients were analyzed with a mean follow-up of 53 months (range 1–162 months). Statistical tests were applied to the data set to search for factors of risk of recurrence.

Results and discussion: The inaugural syndrome was pain (n=52) or a palpable mass (n=3); the tumor was a fortuitous discovery in one case. Comparison with series including both children and adults revealed certain specific features of this pediatric series. The sex ratio was lower in our series; the distal femur localization, frequent in adults, was rare in children. AT one year, the rate of recurrence was 34% in our series (18/53). Fifteen of the 18 recurrences concerned radiologically active (n=12) or aggressive (n=3) tumors. Recurrence predominated in the tarsal bones (3/3), the proximal humerus (6/14), the proximal femur (5/13) and the proximal tibia (3/14). An aneurysmal component was found in 22% of the recurrent tumors and in 16% of those without recurrence. Statistical tests failed to distinguish any significant correlation with recurrence for age, gender, type of treatment, Springfield grade or localization.

Conclusion: The epidemiological data in this series of pediatric chondroblastoma showed features different from adults. The rate of recurrence was particularly high in this multicentric series (but not statistically significant) for localizations in the tarsal bones or a deep joint (with difficult access such as the shoulder and the hip) or with an aneurysmal component.