Lumbar Construct Failure
The patient is a 57-year-old male, with a significant history of cirrhosis of the liver. He was transferred to our institution with lumbar construct failure.
Initially, he presented with severe low back pain secondary to degenerative disc disease and underwent a L4-L5 posterior laminectomy, instrumentation, and fusion. He developed an infection with osteomyelitis and returned to surgery for a posterior instrumentation revision with extension from L3-S1 and anterior L4-L5 interbody fusion. The construct failed with L4-L5 subluxation and graft extrusion.
The patient's symptoms include severe low back pain and bilateral radiculopathy. He is not able to stand or ambulate because of the pain. His Visual Analog Score (VAS) is 9/10. While he has pain-related weakness, there is no focal neurologic deficit or bowel and/or bladder dysfunction.
Upon arrival, we performed percutaneous biopsy of L4-L5 to confirm the infection was not active.
Lumbar anterior posterior (Fig. 1A) and lateral (Fig. 1B) x-rays demonstrate the construct failure at L4-L5.
A lumbar lateral CT scan demonstrates similar findings at L4-L5. (Fig. 2)
Failure of lumbar construct with graft extrusion and subsidence.
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We performed an anterior removal of the interbody cage, L4 corpectomy with anterior column support, and posterior revision of instrumentation with fusion from L2-Iliac.
At one year follow-up, the patient's Visual Analog Score reduced to 3/10 (from 9/10). He ambulates without assistance. There are no signs of infection or construct failure. Anterior posterior (Fig. 3A) and lateral (Fig. 3B) x-rays provide evidence of fusion.
This is a case of an extremely unfortunate patient who initially presented to the surgeon's institution following multiple surgeries for L4-L5 discitis/osteomyelitis and lumbar construct failure. After being transferred with persistent low back pain and bilateral leg pain, a work-up, including plain radiographs, a CT scan with 2D reconstructions, and a percutaneous biopsy of L4-L5 was initiated.
The anterior posterior and lateral radiographs reveal evidence of what appears to be extrusion and subsidence of a femoral ring allograft from the L4-L5 interspace and anterolateral listhesis, as well as significant erosion, of the L4 vertebral body. Since only plain films and a 2D sagittal reconstruction image were provided, we are left with some unanswered questions about the patient's neurologic status. Namely, since the patient presented with bilateral radiculopathy, it would have been helpful to assess the extent and precise location of neurologic involvement with an MRI scan.
In a compromised patient (ie, liver cirrhosis) with failed index and secondary procedures, I would not have taken any chances of an occult infection that could have been missed from a percutaneous biopsy. Although the biopsy was presumed to be negative, I would have also ordered blood work including white blood cell count, erythrocyte sedimentation rate, and C-reactive protein -- not only to rule out infection, but also to obtain baseline levels to track the course of treatment post-operatively. Gadolinium-enhancement and STIR MRI sequences could also have helped to determine the extent of edema/osteomyelitis for pre-operative planning.
Of the treatment options presented, the one chosen by the surgeon appears to be the most rational and comprehensive. Anterior removal of the allograft, L4 corpectomy, and revision instrumentation and fusion effectively solves the issues associated with the failed anterior construct and stabilizes the spine segmentally in a 360-degree fashion. I am assuming that the surgeon also took the time to decompress any neural elements that were found to be compromised on the advance imaging studies in order to address the patient's concomitant radicular symptoms.
Another viable option that was not mentioned, but could serve as an adjunct to the work that was performed, is the lateral approach to the anterior column (eg, XLIF, DLIF). With the advent of deployable retractors and expandable cages, the aforementioned anterior procedures can now be performed through less invasive means through a lateral approach.