Histopathological characterization of melorheostosis.

Melorheostotic bone was examined histopathologically. In the severely affected areas, an abundance of osteoid and increased angiogenesis was observed. Increased osteoid without mineralization indicated the overproduction of bone matrix. Bone resorption also appeared to increase because osteoclasts were numerous in melorheostotic bone, thus suggesting a high rate of bone turnover. In addition, transforming growth factor-beta was immunolocalized in the periosteal fibroblasts, mesenchymal cells surrounding vessels, endothelial cells, and osteoblasts, while basic fibroblast growth factor was found in endothelial cells and mast cells near vessels. These cytokines may have some association with the exuberant bone matrix production and angiogenesis in melorheostosis.

Initial strength of highpressed extrusion poly-L-lactide screw.

We developed a poly-L-lactide material strengthened by a highpressed extrusion technique. The bending strength of a rod made of that material is higher than that of the same size rods made of poly-L-lactide strengthened by drawing technique, which has been used in clinical cases. The purposes of this study were, first to clarify if the initial strength of extrusion-strengthened poly-L-lactide screws is higher than that of draw-strengthened poly-L-lactide screws, and, secondly to investigate the safe torque for driving the screws in clinical usage. In accordance with AO screw design, five kinds of screws were manufactured. In a pull-out test and a twisting test using a DYRACON blocks, the strength of the highpressed extrusion-strengthened poly-L-lactide material was also higher than that of the draw-strengthened poly-L-lactide material after milling into screws. In the simulation using minipig bones and the 4.5 mm psi cortical screws, when the thickness was below 0.5 mm, between 0.5 and 2 mm or over 3 mm, the break locations were in the cortical bone, the thread of the screw and the under head fillet respectively. In the simulation using minipig bones and the 4.0 mm psi cancellous screws, breakage occurred not on the screws but on the cancellous bone in all screws.

Anaesthetic management of two paediatric patients with Hecht-Beals syndrome.

We undertook the anaesthetic management of two children with Hecht-Beals syndrome for orthopaedic surgery under general anaesthesia. Both patients had arachnodactyly, kyphoscoliosis, and multiple congenital joint contractures, but limited mandible excursion was not obvious preoperatively in either, although mental retardation made it difficult for them to cooperate with mouth examination. They had no apparent difficulties with their mouths in daily activities. The anaesthesia records of one patient showed that intubation had been difficult in an earlier procedure. The other patient also had a history of difficult intubation, with slight tearing of the corners of her mouth during an intubation procedure. During slow induction of general anaesthesia with sevoflurane, face mask ventilation was easily performed. We attempted to visualize the larynx under anaesthesia with muscle relaxation, but we were unsuccessful because of the limited mouth opening. After several trials, blind oral intubations were fortunately successful in both patients. There were no postoperative problems with the airway.

Ischio-spinal dysostosis: a previously unrecognised combination of malformations.

BACKGROUND: Ischial hypoplasia is an extremely rare malformation, both as an isolated anomaly and as a syndromic constituent. OBJECTIVE: To elucidate the clinical and radiological characteristics in five patients with the combination of ischial hypoplasia and spinal malformations. MATERIALS AND METHODS: The clinical records and radiographs of two females and three males, ranging in age from 3 months to 38 years, were evaluated. RESULTS: Ossification defects of the ischial rami were symmetrical and total in four patients, whereas the right ischial ramus was partly ossified in the other patient. All patients possessed multiple segmental defects of the spine, with rib anomalies of varying severity. One patient characteristically showed multiple rib gaps, resulting in respiratory distress. Severe anomalies of the cervical spine were evident in two patients. Four patients exhibited lumbosacral hypoplasia, which ultimately led to cauda equina syndrome in three older patients. One patient had mild facial dysmorphism and another had a diversity of anomalies, including ichthyosiform skin changes. Four patients were sporadic cases, whereas the other patient was born to consanguineous parents. CONCLUSIONS: The combination of anomalies in these patients constitutes a recognisable pattern of malformations but may represent a heterogeneous group of disorders.

The diameter of callus in leg lengthening: 28 tibial lengthenings in 14 patients with achondroplasia.

We investigated the relation between callus diameter during bone distraction and the occurrence of late fracture and deformity. We retrospectively reviewed 28 tibial lengthenings in 14 patients with achondroplasia. The minimal diameter of the lengthened zone was measured on radiographs, when the sliding mechanism of the lengthening device was released, and the callus diameter ratio in two planes (CDR; diameter of the callus/diameter of the tibia at the level of the osteotomy end) was calculated. The CDR correlated negatively with the distracted length. Late fracture or late angular deformity occurred in 6 of the 28 lengthenings. When the CDR was 85% or more in both planes, these complications did not occur, but when the CDR was 80% or less in either plane, they occurred in 6 of 20 bones. Careful attention should therefore be given not only to the continuity of the callus but also to its diameter.

Effects of continuous distraction on cartilage in a moving joint: an investigation on adult rabbits.

An animal model, using distraction force on adult rabbits, was developed to study the effects of nonweight-bearing on articular cartilage in a moving joint. Histologic evaluation was used to compare the morphology of chondrocytes, safranin O intensity, cartilage thickness, and structural changes between the test and contralateral joints. At 3 and 6 weeks, the chondrocytes in superficial and intermediate zones were round, with an increase in cellular volume density and mean cell volume and with less metachromasia; the safranin O intensity and cartilage thickness were the same as in the controls. In cartilage of the 9-week group, mean cell volume decreased with cell cloning in the superficial zone, while numerical density increased and mean matrix volume per cell decreased in the superficial and intermediate zones. The cartilage, with a 34% reduction in thickness and a 53-72% decrease in safranin O intensity from the superficial to the deep zone, had superficial fibrotic proliferation, surface erosion or depression, and tidemark irregularity. Continuous distraction in a moving joint caused morphological changes in chondrocytes prior to degeneration of cartilage. These results support the hypothesis that the forces perceived by cells may dictate their shape and then stimulate alterations in cellular biochemistry and matrix metabolism.

Influence of femoral lengthening on hip joint space in posttraumatic femoral shortening.

We performed femoral lengthening for post-traumatic femoral shortening in 14 patients (10 men). The mean age was 26 (17-33) years. The callotasis method was employed using an Orthofix or Hifixator monolateral external fixator. The average length gained was 6 (3-13) cm, equal to 16 (7-36)%. The mean narrowing ratio of the hip joint space during lengthening was 9 (0-26)% and the narrowing persisted at the final follow-up. Cases with narrowing greater than 5% had a longer time between the development of the shortening and the lengthening than the others (p = 0.03). Our findings indicate that femoral lengthening for posttraumatic femoral shortening should be done as early as possible to prevent the development of joint space narrowing during the lengthening procedure.

Narrowing of the joint space of the hip after traumatic shortening of the femur.

Femoral lengthening has been associated with narrowing of the joint space at the hip. We have studied the joint space before lengthening in 20 patients with a short femur due to a femoral-shaft fracture (15) or distal femoral epiphyseal injury (5). Their mean age at injury was 16 years (3 to 27) and the mean shortening was 5.4 cm (1.1 to 14). We found that the hip joint space of the shortened femur was significantly narrower (p < 0.001) than that on the normal side, with a mean narrowing ratio of 15.5% (-5 to +43). The narrowing ratio was directly related to the period spent non-weight-bearing (p < 0.001), but not to the amount of femoral shortening. We have shown that the joint space of the hip in patients with post-traumatic femoral shortening was narrowed even before femoral lengthening had been started.

Callus formation in femur and tibia during leg lengthening: 7 patients examined with DXA.

We examined the callus formation during leg lengthening in 7 achondroplastic patients who underwent 3 bilateral femoral and 4 bilateral tibial lengthenings. Bone mineral content and bone mineral density (BMD) in the lengthened callus space were evaluated every 1 or 2 weeks for 10 weeks after the start of distraction using dual energy X-ray absorptiometry. The mean rate of callus mineralization in femurs (0.64 g/wk) was higher than in tibias (0.22 g/wk). The mean BMD at 10 weeks after the start was 0.35 g/cm2 in the femur and 0.14 g/cm2 in the tibia. Different rates of callus formation in different kinds of long tubular bones have not been reported previously.