The Skeptical Radiology Nurse
A 49-year-old radiology nurse has battled chronic low back pain for years. Her occupation, however has caused her to be wary of back surgery as a treatment option. "I have seen countless patients whose backs were littered with metals and they were still suffering in agony. I've been skeptical of surgery for as long as I can remember."
The patient is a nonsmoker who has undergone extensive nonoperative management for 7 years, including medications, physical therapy, injection therapy (facet blocks and epidurals), and chiropractic care, with no long-term relief.
Her pain is constant and worsens when she is weight bearing and pulling/twisting during procedures at work. She also notes that the pain worsens when climbing stairs and with prolonged sitting. In addition, she has difficulty wearing lead aprons at work. Despite her discomfort, she continues to work. This is not a Workers' Compensation claim.
Her pain is primarily lumbosacral with radiation into the posterior thighs. She rates her pain as 5 to 6 out of 10 at rest, peaking at 7 to 8 with activity.
On examination, the patient demonstrates increased pain with forward flexion. She has moderate paraspinal tenderness, but no pain with sacroiliac joint loading. Neurologically, she has normal strength, intact sensation, and normal reflexes with downgoing toes and negative straight-leg raise.
Discogenic back pain is typically worsened by prolonged sitting, leaning forward, ascending stairs, and weight bearing. The patient had moderately severe degenerative disc disease at L5-S1 with annular tears, modic changes, and clear progression of degeneration on serial imaging. This constellation of findings and her chronic history implicated L5-S1 as the pain generator. I elected not to perform a discogram. Typically, discography is helpful to specify the symptomatic level of pathology when faced with multilevel disc changes on magnetic resonance imaging (MRI). In this case, however, the plain x-ray findings confirmed the suspected pain generator.
Surgical Treatment Options
There was no significant neural element compression, so a simple decompression was not considered. Lumbar arthroplasty is not covered by most US insurance carriers. Furthermore, the literature very strongly favors fusion at L5-S1, because little motion is lost and no benefit has been shown of arthroplasty over fusion at the lumbosacral junction. Surgical fixation and fusion was the selected treatment.
Fusion Options at L5-S1
Fusion of L5-S1 can be addressed using a posterior approach with or without interbody fusion. Interbody graft typically is placed in a posterior lumbar interbody fusion fashion or transforaminal lumbar interbody fusion. The downside of this approach is the need for posterior hardware, such as pedicle screws, which carry inherent risks for malposition, adjacent facet disease, and traumatic disruption of the lumbar musculature. The posterior approach provides somewhat limited disc distraction and relies on a small interbody graft resting inside the apophyseal ring.
Another treatment option is an axial lumbar interbody fusion (AxiaLIF), or transacral approach. This approach is specialized for L5-S1 disease, but in my experience provides mixed long-term results.
The anterior lumbar interbody fusion (ALIF) retroperitoneal approach affords many benefits (see Table) and is my preferred approach for L5-S1 pathology. The major limitation is that it typically requires a second access surgeon, such as a general or vascular surgeon.
This patient’s body mass index and history were very favorable to an anterior approach. An anterior discectomy was carried out, followed by distraction of the disc space. The endplates were decorticated to enhance fusion mass formation. An interbody cage filled with bone marrow aspirate and allograft was used to maintain the distraction. The chosen implant had internal screws (two down, one up) to enhance fixation into the neighboring bone (see Figures 6-7).
Two weeks after surgery, the patient reported pain levels of 2 to 3 out of 10 on a visual analog scale and requested, but was declined, permission to return to work. At 6 weeks post-op, the patient reported a 0 to 1 pain score and increased mobility from her preoperative status. She returned to work on full duty and remains gainfully employed 1 year after surgery.
This case demonstrates several factors that typically lead to positive surgical outcomes. First, this patient was working despite her pain and remained committed to returning to work. She was on minimal preoperative narcotics, having followed only short-term regimens under the direction of her pain management physician. Her pain scores were rational and accurate. Patients routinely citing pain levels of 10 out of 10 rarely demonstrate good outcomes. While several discs showed early degenerative changes, her active pathology was confined to a single level. Her pathology was demonstrated on different imaging modalities. The ubiquitous “dark disc” was confirmed by bone changes on short T1 inversion recovery (STIR), MRI, and plain film imaging. Finally, her pain correlated with activity and her history confirmed a discogenic source for her pain.