We present the histological findings of bone retrieved from beneath the femoral components of failed metal-on-metal hip resurfacing arthroplasties. Of a total of 377 patients who underwent resurfacing arthroplasty, 13 required revision; for fracture of the femoral neck in eight, loosening of a component in three and for other reasons in two. None of these cases had shown histological evidence of osteonecrosis in the femoral bone at the time of the initial implantation.

Bone from the remnant of the femoral head showed changes of osteonecrosis in all but one case at revision. In two cases of fracture which occurred within a week of implantation, the changes were compatible with early necrosis of the edge of the fracture. In the remaining six fractures, there were changes of established osteonecrosis. In all but one of the non-fracture cases, patchy osteonecrosis was seen.

We conclude that histological evidence of osteonecrosis is a common finding in failed resurfaced hips. Given that osteonecrosis is extensive in resurfaced femoral heads which fail by fracture, it is likely to play a role in the causation of these fractures.

Objective: Spontaneous spinal subdural haematoma is a rare cause of spinal cord compression usually confined to a few vertebral levels. When the haematoma extends over several spinal segments, surgical decompression is a major undertaking. A minimally invasive technique of decompression, using topical recombinant tissue plasminogen activator (rt-PA), is presented in two patients with extensive spinal intradural haematoma.

Clinical Presentation: Two patients, receiving long-term anticoagulation therapy, presented with acute-onset back pain progressing to paraparesis. MRI of the spine demonstrated spinal subdural haematomas extending over fifteen vertebral levels in one and twelve in the other patient.

Intervention: An angiography catheter was introduced into the subdural space through a limited laminectomy. Thrombolysis and evacuation of haematoma was then achieved by intermittent irrigation of the subdural space with recombinant tissue plasminogen activator (rt-PA), followed by saline lavage. Post-operative imaging demonstrated satisfactory decompression in both patients. There was significant improvement of neurological function in one patient.

Conclusion: Topical application of rt-PA for spinal sub-dural haematoma allows evacuation of the haematoma through a limited surgical exposure. Decompression of the subdural space by this minimally invasive technique may be advantageous over extensive surgery by minimizing surgical exposure, reducing postoperative pain and risk of neuronal injury. This technique may be useful in patients presenting with compression extending over several vertebral levels or poor surgical candidates.