Dysplasia Epiphysealis Hemimelica (DEH) also known as Trevor's Disease is a rare developmental disorder resulting in cartilaginous overgrowth of the epiphysis of long bones. DEH is usually diagnosed in children between two and eight years old and it is three times more often diagnosed in boys. The most reported complaints are pain, limitation in range of motion, and deformity or swelling of the affected joint. Treatment of symptomatic lesions consists of surgical resection of the lesion, resulting in good long-term results. Based on histological evaluation, DEH is often described as an osteochondroma or an osteochondroma-like lesion, although there are clinical, radiological and genetic differences between DEH and osteochondromas. To investigate the hypothesis that DEH and osteochondromas are histologically identical, two cases of DEH and two cases of osteochondromas in patients with Hereditary Multiple Osteochondroma (HMO) are compared at histological level. Tissue samples from patients with a histopathologically confirmed diagnosis of DEH were compared with two age and gender matched patients diagnosed with HMO. After tissue sampling and processing, (immuno)histological stainings were performed for Collagen type II, Collagen type X, Sox-9 and Safranin-O. Histologically, clumping of chondrocytes in a fibrillar matrix, a thick disorganized cartilage cap and ossification centres with small amounts of unresorbed cartilage were observed in DEH. In contrast, chondrocyte organisation in cartilage of osteochondromas displays characteristics of the normal growth plate. In addition, differences in expression of collagen type II, collagen type X and Sox9 were observed. Collagen type II was expressed in the extracellular matrix surrounding proliferative and hypertrophic chondrocytes in osteochondromas, while weak expression was observed in the entire cartilage cap in DEH. Collagen type X was not expressed in DEH, while expressed in the pericellular matrix surrounding hypertrophic chondrocytes in osteochondromas. Staining for Sox9 was positive in the hypertrophic chondrocytes in osteochondromas, while expressed in the nuclei of all chondrocyte clusters in DEH. Both morphological and immunohistological differences were observed in histological sections of DEH and osteochondromas. These findings reject our hypothesis, and supports the earlier observed clinical, radiological and genetic differences and implies a different aetiology between DEH and osteochondroma formation in HMO

We performed arthrodesis with a cobra head compression plate in 18 young adults with severely degenerative arthritis of the hip. The aetiology was trauma in 4 patients, sepsis in 3, slipped upper femoral epiphysis in 3, Perthes disease in one, acute lymphblastic lymphoma in one, alcohol related avascular necrosis in 2, epiphyseal dysplasia in one, multiple osteochondromatosis in one, (bilateral) idiopathic chondrolysis in one and in the remaining case there was no apparent cause. At a mean follow up of 4 years 14 patients were complaining of back pain compared to 4 patients preoperatively. Preoperatively 4 patients had ipsilateral knee pain compared to 5 patients postoperatively. Four patients complained of pain at rest or night. Eleven of the 18 patients have returned to work. The average score of satisfaction on a scale of zero to ten was 7.2, with only 3 patients giving a mark of 4 and below. The management of osteoarthritis of the hip in the young adult is challenging and arthrodesis of the hip is a reasonable option for the very painful arthritic hip