الفهرس 
Histopathology and Genetic Basis of OsteochondromaOnly 14 pages are availabe for public view
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Abstract
Hereditary multiple exostoses is a cartilage-covered bony excrescence that arises from the surface of a bone. It is the most common benign bone tumors in children. It is an autosomal dominant skeletal disorder caused by mutations in one of the two EXT genes. Hereditary multiple exostoses were previously thought to have a male predominance it now appears to affect both sexes equally.
The growth of an osteochondroma results from a defect in the circumferential ring of perichondrium, known as the ring of Ranvier, there is also a defective in long bone remodeling
Microscopic evaluation shows a typical benign chondrocyte has a single small nucleus. During active bone growth binucleated chondrocyte may be seen in.
Multiple hereditary exostoses clinically presented by single or multiple hard painless or painful masses near the joints. Pains become a common presentation with malignant transformation and bursal inflammation. Impaired body growth symmetrical or asymmetrical is seen.
Forearm involvement has been linked to the overall severity of the disease. Radial bowing may occur as a result of disproportionate ulnar shortening. The hands are usually asymptomatic. Femoral anteversion, valgus deformity, acetabular dysplasia, broadening of the metadiaphyseal junction results in an Erlenmeyer flask deformity at metadiaphyseal junction most prominent at the distal femur.
Plain film radiography re¬mains the cornerstone of diagnostic imaging for bone tumors, and determining its biologic aggressiveness.
MRI may provide a more confident identification of aggressive features such as joint involvement or a soft tissue mass and measuring the cartilaginous cap. CT scanning can provide excellent bone detail of osteochondromas developing in the spine, shoulder, or pelvis. The bone scan did not qualitatively differentiate the benign active exostoses from the lesions with malignant degeneration. Arteriography is considered essential in planning surgical treatment.
The disproportionate shortening of the ulna is attributed to First: because the dis¬tal ulnar physis is responsible for greater longitudinal growth relative to that of the distal radius, Second: bones with a smaller cross-sectional diameter tend to be shortened more considerably when affected by hereditary multiple exostoses.
Taniguehi classified his patients according to extend of forearm involvement, Masada and Ono classified forearm deformities according to the morphology of the defor¬mity.
Simple tumor excision can correct the forearm deformity in patients with an isolated tumor of the distal part of the ulna. Conversely, tumors involving the distal ulna and distal end radius, tumor excision alone are a less promising.
Three methods of ulna lengthening were employed; lengthening by the Ilizarov technique for multiplanar deformities, an Orthofix monolateral frame for uniplanar deformity and acute ‘step-cut’ osteotomy with plating.
Radial correction can be done by osteotomy and fixed by K-wires or plates and screws. Himiepiphysial stippling can be done.
Modified Sauvé-Kapandji is done by ulnar shaft transaction 1.5 to 2.0 cm proximal to the distal end and fixed to the radius by k wire.
Forearm rebalancing by radioulnar fusion and creation of a single-bone forearm is an indicated procedure in the osteochondromatoses patient with Pain and limited function and marked deformity.
Dislocation of the radial head is managed by excision of the radial head. Attempts of surgical relocation is not successful
Fracture of an osteochondroma is an unusual complication. Peripheral and central lesions may compress nerves. Bursa formation most often occurs in osteochondromas with overlying moving tissues that cause friction. Vascular complications due to osteochondromas are rare, being more common in young adults. Malignant degeneration of the cartilaginous portion of the osteochondroma into secondary chondrosarcoma is common and rarely osteosarcoma can occur.