Severe Osteoporosis with Lumbar Instability

A 68–year–old retired female nurse presented with a 2–year history of progressive severe low back and bilateral leg pain with numbness when she attempted to stand. These symptoms were completely relieved by lying down. Walking was limited to less than 5 feet by excruciating pain. Sitting tolerance had deteriorated to less than 10 minutes. Bowel and bladder function were intact. Multiple courses of physical therapy, medications, external immobilization, and injections had failed to relieve her symptoms.

Her history was notable for kidney failure requiring hemodialysis three times per week since 1980. This condition was related to hyperparathyroidism requiring parathyroidectomy in 1970.

Physical examination revealed tenderness in a diffuse distribution over the lumbosacral region. Motor and sensory function were grossly intact throughout both legs, although reflexes were absent bilaterally and both legs were slightly atrophic. All tests for root tension signs were negative.

Supine AP and lateral plain films (Figs 1, 2) showed severe osteopenia, extensive loss of L4–5 disc height, severe chronic osseous changes involving L4 and L5, cuneiform L5, and suggested L5 spondylolysis. A standing lateral film (Fig 3) demonstrated axial instability with a collapse and loss of lordosis at L4–L5 and L5 and S1. CT confirmed L5 spondylolysis (Fig 4). MRI (Figs 5, 6) documented segmental stenosis, primarily at L4–L5. EMG and SSEP were non–diagnostic for technical reasons.

Fig. 1	Fig. 2	Fig. 3	Fig. 4	Fig. 5	Fig. 6
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Severe Osteoporosis with Lumbar Instability: Discussion

Roger Jackson, MD
North Kansas City Hospital, North Kansas City, MO

This patient has bony destruction at L4, L5, and S1, advanced involvement of the L4–5 disc, and changes in the L5 and S1 endplates. Differential diagnosis should include metabolic bone disease (with history of hyperparathyroidism) and infectious spondylodiscitis (due to possible hematogenous seeding from renal failure, hemodialysis, TB, etc.). Clauditory symptoms could be due to spinal stenosis or peripheral vascular disease with marked aortoiliac calcification. X–rays show some collapse at L4–5 and L5–S1 with standing on the lateral x–ray.

Myelogram and biopsy are recommended with orthotic management and appropriate long–term antibiotics if infection is present. Due to poor health and bone quality (severe osteopenia) there are many risks for surgical intervention, especially for fusion. Surgery should be considered if cauda equina syndrome starts to develop. Autofusion and stability can occur anteriorly if an infection is aggressively treated, especially if bacterial. At this point, decompressive lumbar laminectomy could be considered. In my experience, more extensive surgery than this is extremely risky in such patients and fraught with complications.

Discussion
Claude Argenson, MD
Hôpital St. Roch, Nice, France

We are faced with a case of severe osteoarthritis with the beginning of retrolisthesis at L4–L5 and a spondylolysis at L5. The neurologic dysfunction is linked to the stenosis at L4–L5 and requires decompression to favor recuperation. There is also a high level of lumbar pain, a sign of disc destruction which requires stabilization. Both aims can be achieved by a single posterior approach. This will enable the ablation of the posterior arch of L5, possibly with a bilateral foraminotomy at L4–L5 and a stabilization at L4–L5–S1 by PLIF. Two cages would be screwed together at L4–L5, thus restoring disc height and creating good anterior fusion. The anterior arthrodesis at level L4–L5 needs to be accompanied by a posterior osteosynthesis in compression, with screws in L4, L5, and S1.

Difficulties may occur in the anchorage of the sacral screws which need to be placed obliquely: 10š internal angle directed toward the sacral plate in sub–cartilaginous portion. The lower anchorage site could also be completed by a double hold using a Chopin Block™ or a bar, such as Stéphanie. The extent of the destruction of the lower plate of L5 might also lead to a cage being put in this space. A bone biopsy is necessary to determine post–operative medical treatment.

Finally, if the upper anchorage of the screws in L4 should prove insufficient, a median hook may be added above the lamina of L4. The bone material of the L5 lamina should be used for the bilateral posterolateral graft, which will be necessary. This could be completed by a bank graft used in conjunction with the autograft. Depending on the strength of the construct, external post–operative support may be considered if there are difficulties during the insertion of the screws.