We reviewed 64 patients in whom 66 acetabula had been reconstructed with either the Muller ring (46) or the Burch-Schneider anti-protrusio cage (20) at a mean follow-up of five years. Five hips had been revised a second time for loosening, all after a Muller ring had been used for a medial segmental defect (2), ungrafted cavitary defects (2) or after resorption of a block graft (1). The use of bone grafts with the implants reduced the incidence of failure from 13% to 6% and of circumferential radiolucent lines at the bone-implant interface from 39% to 2%. The Muller ring is indicated for acetabula with isolated peripheral segmental defects or cavitary defects confined to one or two sectors. The Burch-Schneider cage should be used for medial segmental defects, extensive cavitary defects and combined deficiencies. Defects should be reconstituted with bone graft rather than cement.
1. Thirty-seven cases of fracture of the dens have been studied. 2. The incidence of non-union was high: 64 per cent after apparently adequate closed treatment. 3. Possible causes of the high incidence of non-union have been studied : attention is drawn to the effect of displacement and to that of posterior displacement in particular. 4. Non-union of the dens with potential instability at the atlanto-axial joint is not acceptable in a patient who expects to lead a normal active life. 5. Atlanto-axial fusion is the method of choice in the treatment of instability ; once that has been secured, pseudarthrosis of the dens is no longer significant.
1. The syndrome of spinal stenosis is due to compression of the cauda equina from structural narrowing of the lumbar spinal canal. 2. Patients with this syndrome present symptoms of cauda equina claudication or of unremitting bizarre back pain and sciatica. 3. The compression of the cauda equina is always posterior and postero-lateral and is caused by narrowing of the lateral recesses and of the dorso-ventral diameter of the spinal canal. 4. The diagnosis can be made only by myelography. The only form of successful relief of the nerve root compression in spinal stenosis is adequate lateral and longitudinal decompression.
