Lumbar Arthroplasty Revision

History

A 44-year-old woman presented in our office with low back pain and difficulty with defecation. The patient had surgery 2 years earlier with the implantation of an artificial lumbar disc. The surgery did not reduce her low back pain. A year post-op she developed increased low back pain that was made worse with ambulation. The patient did not have any leg symptoms, but she developed urge fecal incontinence (ie, as soon as she felt she had to open her bowels, she either went immediately or lost control and soiled).

Prior Treatment

Two years prior to presentation in our office, the patient underwent an L5-S1 lumbar artificial disc implantation.

Examination

The examination was unremarkable. The patient was neurologically intact.

Pre-operative Images

Figure 1: Lateral x-ray showing disarticulation of the 3-piece lumbar arthroplasty device with ventral displacement of central core.

Figure 2: Lateral and AP myelogram. Minimal posterior bulging of the L5-S1 annulus is noted, but no major neurological compression is present.

Figure 3: Pelvic arteriogram defining the relationship of the device to the iliac arteries. As expected, the device was below the bifurcation at L5-S2.

Figure 4: Reconstructed sagittal CT myelogram views. There is a lot of artifact from the device. No neural compression is noted.

Figure 5: Axial CT scan of the L5-S1 interspace. The complete dislocation of the central core is evident with bowel loops located anterior to this. The facets look sclerotic.

Diagnosis

Disassembly of the lumbar artificial disc implant with compression of the rectum by the extruded cord.

Selected Treatment

The patient underwent an anterior approach after angiography with a vascular surgeon. Upon visualization, the core was identified to be compressing the posterior wall of the rectum. The core was removed uneventfully. The shells were encased in bone and L5-S1 was found to be fused. No revision was effected.

Intra-operative Images

Figure 6: Intra-operative view of the exposure with the core and outer shells being dissected free from surrounding tissues.
Figure 7: The polyethylene core was surrounded by a pseudomembrane that, once opened, allowed easy removal of the core. The rectum was indented by the core, but the outer wall was intact.
Figure 8: Retrieved core, relatively intact.

Outcome

After surgery, the patient's bowel symptoms resolved. The L5-S1 level was thought to be fused, and her pain was coming from the adjacent L4-L5 facets. She responded well to NSAIDs and facet blocks.

Case Discussion

Richard G. Fessler, MD, PhD

Professor of Neurosurgery

Rush University Medical School

Dr. Sekhon presents an interesting and challenging case of core extrusion/failure of an L5-S1 arthroplasty. This and similar complications of lumbar arthroplasty are becoming more frequently noted, and alternative salvage strategies are being conceived and developed. Dr. Sekhon lists several of these, such as posterior fusion, lateral approach and removal of the core, and anterior approach and removal of core with either replacement or fusion.

Given the rectal compression, posterior fusion alone is not an option. A lateral approach to L5-S1 is also not feasible, although this may provide an excellent option at L3-L4 and L4-L5. Thus, only anterior approaches are options for this particular patient. Unfortunately, this approach can be hazardous, and complications up to and including death have been reported.

These complications stem from the difficulty of dissecting and exposing the region of the disc extrusion through a field of scarred major vessels. Ooij et al, for example, discuss a variety of early and late complications of lumbar arthroplasty. Among their removal and "salvage" fusion patients, they reported that less than 50% of the patients benefited (Journal of Spinal Disorders and Techniques. 2003;16:369-383).

Dr. Sekhon provided an excellent solution to this patient—one that provided immediate relief of the patient's symptoms. It is unclear how and where the patient fused. It will be interesting to observe, therefore, if the patient will eventually go on to require fusion augmentation.