Internet Keyword: South Florida Spine
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Internet Keyword: South Florida Spine
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Courtesy of:
South Florida Spine Institute, Mount Sinai Medical Center, Miami Beach, FL, USA
The patient, a 70–year–old man, presented with a history of severe back and left lower extremity radiculopathy over several weeks. He was unable to walk. The patient underwent MRI scanning demonstrating severe L3 to L5 spinal stenosis with Modic endplate changes located at the L4/L5 endplates. The patient failed non–operative treatment, and subsequently underwent a decompressive laminectomy with a L4/L5 posterior lumbar interbody fusion. Postoperative pain was minimal at 2–week follow–up and the patient was ambulatory without any assistive devices. Approximately 6 weeks after the spinal fusion, the patient complained about increasing back pain, which, once again, limited his ambulation secondary to pain. The postoperative brace did not provide any significant relief to this new pain; however, the patient did not develop new–onset lower extremity radiculopathy. Physical examination demonstrated a healed surgical wound without swelling or erythema. It was noted that there was pain on palpation within the extent of the surgical wound, and the patient had significant back pain upon transferring from the wheelchair to the examination table. No visible spinal deformity was present and the neurological examination was normal. Radiographs demonstrated an intact posterior lumbar instrumented fusion. The interbody graft did not change position from the operative films. The L3 vertebral body appeared to have decreased in height compared with preoperative films (Figs. 1 and 2). MRI evaluation revealed postoperative edema within the L4 and L5 vertebral bodies as expected, and demonstrated bone marrow edema (as visualized by signal intensity that was increased on T2 and STIR [Short Tau Inversion Recovery], and decreased on T1 weighted images) within the vertebral body of L3 (Figs. 3 and 4). The loss of vertebral body height was visualized, with no bony retropulsion into the spinal canal. A diagnosis of an acute L3 vertebral compression fracture was made. With the significant diminution of rehabilitative ability, the patient’s primary surgeon felt that the fracture was a postoperative complication. The patient was referred for vertebral stabilization. With a medical history significant for chronic obstructive pulmonary disease, as well as previous osteoporotic left hip and shoulder fractures, this man was felt to be at elevated risk for further fracture progression and occurrence. The patient was given option to either continue postoperative bracing or undergo vertebral body stabilization with augmentation by kyphoplasty at L3. The patient had a successful kyphoplasty procedure performed at L3 (Figs. 5 and 6), utilizing a bilateral transpedicular approach. A biopsy performed during this procedure was read as ‘bone with recent marrow hemorrhage.’ The patient was discharged in a stable condition, only using acetaminophen for mild postoperative pain. The use of the surgical brace from the primary procedure was continued as a reminder to the patient to avoid excessive flexion during the following 4 weeks. The patient was started on appropriate oral antiresorptive agents and has continued to progress well from his fusion, with no new vertebral compression fractures reported at 1–year follow–up. Discussion As more instrumented spinal fusion procedures continue to be performed, ‘adjacent segment disease’ is considered by many to be a possible long–term consequence [1]. This is thought to be related to altered biomechanical forces at the mobile level adjacent to the fusion, and may result in the development of spinal stenosis, disc herniation, and instability above or below a spinal fusion. The development of a segmental vertebral fracture after spinal fusion is a less–reported postoperative complication. This case demonstrates the effect of a significantly stiff spinal fusion on an adjacent vertebral segment. In patients with osteoporotic bone, rigid spinal fusion may predispose to development of fracture at adjacent vertebral levels. This relatively uncommon event appears to be the result of increased biomechanical stress to a motion segment adjacent to the fusion. In this case, a laminectomy with excision of the interspinous ligament was performed. This excision, along with the fused segment, may increase flexion/rotation and posterior shear in the adjacent motion segment [2]. With compromised bone strength, this stress may result in vertebral compression fracture [3]. Treatment of adjacent segment osteoporotic fracture after rigid spinal fixation appears to be amenable to vertebroplasty and kyphoplasty techniques. Kyphoplasty may also potentially restore vertebral height and sagittal alignment [4]. This case illustrates how kyphoplasty technique was utilized to enable the patient to resume a normal recovery status post fusion. The use of polymethylmethacrylate (PMMA) or hydroxyapatite has been reported with regard to surgical planning in osteoporotic spinal fusion. However, the literature only pertains to the augmentation of spinal fixation in osteoporotic patients [5]. The addition of PMMA in this fashion only addresses pedicle screw–bone interface, where it tends to increase the pullout strength in osteopenic bone [6]. Several spine surgeons have anecdotally reported on prophylactic vertebroplasty procedures for osteoporotic patients undergoing multilevel stabilization procedures. The vertebral augmentation is performed at the levels above or below the instrumented fusion; however, this practice has not been formally reported in the literature. There appears to be a correlation with low bone density and secondary fractures after PMMA stabilization in osteoporotic vertebral fractures [7]. Currently, there is no research that legitimizes the use of prophylactic vertebral augmentation in segments adjacent to spinal fusion or vertebral fracture stabilization procedures. This case highlights the pitfalls of fusion in osteoporotic bone and illustrates one potential solution to avoid adjacent level collapse. Address for correspondence: Jonathan A Hyde, South Florida Spine Institute, 4302 Alton Road, Suite 115, Miami Beach, FL 33140, USA. References
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