Primary disorders of bone with 'spinal block'.

Two hundred and thirty-two cases of compression of the spinal cord or cauda equina included 11 cases where compression was entirely due to a primary bony disorder and 20 further cases where developmental spinal stenosis was the main cause of compression. The former group consisted of two cases of Paget's disease and one each of polyostotic fibrous dysplasia, chondrosarcoma, achondroplasia, spondylo-epiphyseal dysplasia, Klippel--Feil syndrome, haemangioma of bone, primary bone reticulosarcoma, osteoporotic fracture and vertebral osteomyelitis. Three patients, with fibrous dysplasia, chondrosarcoma and Paget's disease with recurrent compression respectively, are described and the relevant literature is reviewed. The large number of primary disorders of bone which can cause cord compression are tabulated. Cord compression is a rare complication in most of these disorders but collectively they caused 13% of the cases of spinal block in this series.