Remodelling of the distal radius after epiphysiolysis and lengthening.

Arrest of growth of the distal radius is rare but will produce deformity of the wrist. We corrected angular deformity and shortening of the distal radius by epiphysiolysis and gradual lengthening without a corrective osteotomy.

The effect of posterior spinal fixation with bone cement upon vertebral growth in dogs. An experimental study.

In an experimental study the authors tried to clarify the effect on vertebral growth and spinal curvature in dogs following fixation of the posterior elements of the spine at different levels using bone cement. In three separate experimental groups a segment of the dorsal spine, the dorso-lumbar spine or the lumbar spine was securely fixed with bone cement incorporating a radio-opaque wire marker. Growth of the spine was observed with renal X-rays over a six-month period and the following results obtained: 1. Growth in height of the vertebra was not affected by the fixation; 2. The intervertebral disc spaces widened anteriorly and narrowed posteriorly even when fracture of the bone cement occurred; 3. Increasing lordosis developed in all three experimental groups even when a physiological kyphosis was normally present. The greatest increase occurred in the lumbar spine; 4. Fracture of the cement occurred consistently when attempting to secure the dorso-lumbar junction.

The normal and regenerated meniscus in rabbits. Morphologic and histologic studies.

The chronologic development of normal and regenerated menisci in immature and adult rabbits, studied by gross, histologic, and histochemical means, revealed that grossly regenerated menisci were less glossy and smaller than normal, with blunt margins and firm attachments to the synovial membrane. The normal meniscus of five-week-old rabbits consisted of fibroblasts and fibrocytes without cartilage cells. In 12-week-old rabbits fibrocytes in the normal meniscus had been transformed into round or oval cells lying within lacunae, the halos of which stained with safranin O. In the typical regenerated meniscus fibrocartilage cells appeared 12 weeks after meniscectomy in young rabbits and 24 weeks after meniscectomy in adult rabbits. Cartilaginous transformation occurred infrequently and only in isolated areas of the meniscus. Cartilaginous transformation in regenerated menisci appeared in 10.6% of the knees in young rabbits and in 8.1% in adult rabbits.

The effect of synovectomy on the articular cartilage of the knee joint in rabbits.

Subtotal synovectomy was performed on the right knee joints of 20 immature and 20 mature rabbits, and articular cartilage from the femoral and tibial condyles and the patellae was examined at 1, 3, 5 and 12 weeks after operation. Specimens from the unoperated left knees provided the controls. Each specimen was examined macroscopically and with histological (H-E stain) and histochemical (safranin-O stain) techniques for abnormalities in structure, cell population, stain intensity and distribution. The femoral articular cartilage was most affected by synovectomy. The tibial articular cartilage was only moderately affected and the patellar articular cartilage was even less affected. The histochemical changes were transient and reversible, being more severe and prolonged in the mature animals. No changes in either group were noted on gross inspection or in the H-E stained sections.

The effect of posterior spinal fixation with acrylic cement on the vertebral growth plate and intervertebral disc in dogs.

We have attempted to clarify the serial histological changes in the growing spine of dogs following posterior fixation with acrylic cement. Twenty-four male mongrel dogs aged 8 weeks were used for the study. The lumbar spine from L.3 to L.5 was fixed posteriorly with acrylic cement. Three dogs were then sacrificed every four weeks up to 32 weeks, and the histological changes of the vertebral disc, growth plate and vertebral bodies were observed by light microscopy. Thinning of the growth plate and distortion of the cartilage columns has been demonstrated, but premature fusion of the growth plate did not result and vertebral body growth continued. Anterior wedging of the intervertebral disc was seen with some thinning of the bony trabeculae of the vertebral body. Degeneration of the nucleus pulposus resulted, with replacement by fibrous tissue. The normal horizontal arrangement of the fibres of the annulus fibrosus altered to a vertical configuration by 32 weeks.

The response of nerve tissue to chymopapain.

This study was undertaken to clarify the effects of topically injected chymopapain on the spinal cord and peripheral nerves in rabbits, and also the effect of ganglioside on sciatic nerves which had been damaged by chymopapain. There were no abnormal macroscopic or microscopic findings when chymopapain was injected around the sciatic nerve sheath or around the spinal dura mater, but when it was injected directly into the nerve sheath there was immediate paralysis and severe axonal necrosis; the Schwann sheath remained intact and there was haemorrhage. Injection into the dura resulted in massive haemorrhage, perivascular neutrophil infiltration and necrosis of grey matter. In those treated with ganglioside, regeneration of the damaged sciatic nerve was shorter than in those not so treated.

Tuberculosis of the ischiopubic ramus. A report of five cases.

Five cases of tuberculosis of the ischiopubic ramus are reported. All presented with abscesses. Treatment by simple curettage and INH, rifampicin and ethambutol given for 18 to 24 months gave satisfactory results in the 4 patients who were children. The one adult had severe disruption of the symphysis pubis, and sacroiliac involvement; a good result was obtained after bone grafting and fixation with a plate.

Recurrent parosteal osteosarcoma of the talus in a 2-year-old child.

Parosteal osteosarcoma is an uncommon, low-grade malignant bone tumor and is found in an older age group than conventional osteosarcoma. We present a talar parosteal osteosarcoma that recurred twice in a 2-year-old child. To our knowledge, this is the youngest patient reported with a parosteal osteosarcoma. The talus is an unusual site for parosteal osteosarcoma. Inadequate resection due to a diagnosis of juxtacortical chondroma resulted in recurrence of the tumor. The age of the patient, the thick cartilaginous cap, and well-differentiated trabecular bone all contributed to the critical erroneous diagnosis.

Nonossifying fibroma: characteristics at MR imaging with pathologic correlation.

PURPOSE: To correlate the findings of nonossifying fibroma at magnetic resonance (MR) imaging with those at pathologic examination. MATERIALS AND METHODS: In 19 patients (age range, 8-25 years; mean age, 14 years) with pathologically proved nonossifying fibroma, MR images were analyzed for signal intensity and patterns of contrast enhancement. Findings at MR imaging and biopsy were correlated. RESULTS: On T1-weighted images, all nonossifying fibromas had low signal intensity compared with that of skeletal muscle. On T2-weighted images, 15 lesions (79%) were hypointense and four (21%) were hyperintense. On gadolinium-enhanced images, intense contrast enhancement was seen throughout 15 lesions (heterogeneous pattern in 12 and homogeneous in three) and in the margins and septa in four. Extensive hypercellular fibrous tissue and hemosiderin seen at pathologic examination were depicted with low signal intensity on T2-weighted MR images. CONCLUSION: The distinguishing features of nonossifying fibroma included hypointensity and septation on T2-weighted images. Signal intensity on T1- and T2-weighted MR images and the patterns of contrast enhancement were dependent on the amounts of hypercellular fibrous tissue, hemosiderin, hemorrhage, collagen, foamy histiocytes, and bone trabeculae.

Chondroblastoma: MR characteristics with pathologic correlation.

PURPOSE: The purpose of this study was to describe the MR findings of chondroblastoma with pathologic correlation. METHOD: In 22 patients with pathologically proven chondroblastoma, MR signal characteristics were correlated with pathological findings. RESULTS: On T2-weighted images, 12 (55%) lesions were hyperintense with hypointense areas in 9 lesions, whereas 10 (45%) were hypointense. Therefore, 19 of 22 (86%) lesions with pathologic correlation had hypointense areas entirely (n = 10) or partly (n = 9) on T2-weighted images. On gadolinium-enhanced images, 13 (59%) lesions showed lobular enhancement and 9 (41%) showed marginal and septal enhancement. Low signal intensity on T2-weighted MR images was most strongly associated with an abundance of immature chondroid matrix, hypercellularity of the chondroblasts, calcifications, and hemosiderin on histology. CONCLUSION: Chondroblastoma was found to show hypointense portions on T2-weighted images. Signal intensity on T1- and T2-weighted MR images in chondroblastoma was dependent on the amounts of histopathological components.