Objective: To evaluate the long term results of an operation developed to decompress the roots at the stenotic level, preserve the midline structures, and not use instrumentation or fusion.

Design: A retrospective clinical and radiological review of consecutive patients operated on for spinal stenosis secondary to lumbar spondylosis.

Subjects: One hundred and sixty patients (eighty seven female and seventy three male) with a mean age at operation of sixty eight (range 40–90). Sixty one patients (38%) had a degenerative listhesis causing stenosis. The mean post operative follow-up was twenty two months (range two months to fourteen years).

Summary of background data: Lumbar spondylosis, commonly involving degenerative listhesis, is the commonest cause for spinal stenosis in the lumbar spine. Surgery offers the only permanent cure. The standard procedure remains a laminectomy with fixation and fusion in the presence of possible instability. The laminectomy destabilises the spine and the instrumented fusion makes it a much bigger operation in patients often not best placed to cope with it. There is a need, therefore, for an effective operation that does not compromise spinal stability.

Results: At six weeks one hundred and forty one patient (85%) reported relief of leg pain and a further nine patients were improved at three to six months. 52% of the patients reported a concomitant improvement in back pain. The results were sustained at follow-up.

The operation was not responsible for the development of a new spondylolisthesis. A minimal increase in an existing degenerative listhesis was seen in two patients only without compromise of their good results. There was no revision surgery at any of the operated levels.

Conclusions: The operation of segmental spinal decompression for degenerative lumbar spinal stenosis has been found to be effective, safe, and give good long term results, without compromising the existing spinal stability. Patient selection and attention to operative technique are essential.

Introduction: Allen and Ferguson in 1982 described five stages of compression extension injury to the cervical spine; the first stage that was considered as a stable injury involves fracture of the articular process, pedicle or lamina which may be associated with a rotary spondylolisthesis. This fracture pattern, which is not uncommonly missed on the initial X-rays, can be diagnosed using CT scanning especially if patients present with root symptoms. This fracture will be usually treated conservatively as a stable injury. In practice we found out that this type of bony fracture might present later on with subluxation and/or persistence of symptoms even if treated in rigid immobilisation devices including halo jacket. The hypothesis around this fracture pattern will be a hyperextension mechanism combined with a degree of lateral tilt and rotation producing an anterior annular disruption under tension and a unilateral posterolateral mass or laminar fracture under compression with a resultant rotational instability around the intact lateral mass.

Material and Methods: Ten patients with stage I compression extension injury who presented with subluxation were studied prospectively aiming for addressing the patho-anatomy and define a method for treatment. All the cases presented with neurological manifestations, nine cases with root symptoms and one case with incomplete cord injury. The treatment consisted of early closed reduction followed by anterior fusion and fixation.

Results and Conclusion: All patients showed neurological improvement. Radiological union was achieved in all the patients with maintenance of the alignment. In conclusion, extension compression injury type I (fracture of the bony posterior elements) is usually a stable injury but if there is additional failure of the disc this segment will be rendered rotationally unstable. Despite the limited number of patients in this series the results of early anterior fusion with fixation were very satisfactory encouraging the recommendation for using this type of treatment.