Should TLIF be Routinely Used in a 60-Year-Old Man With a Mild Degenerative Spondylolisthesis?
Although there are many causes of lumbar spondylolisthesis, DS is by far the most common. Affecting roughly 6% of the population, DS most frequently occurs at the L4–5 level.1,2 Patients typically present with back pain, radiculopathy, or claudicatory symptoms which are caused by segmental instability and compression of neural elements. When a trial of conservative treatment fails, it is well established that surgical treatment for DS produces better long-term outcomes than nonoperative management.3–6 The question then arises what the optimal surgical management is with a wide spectrum of potential options including decompression alone, decompression with posterolateral fusion (PLF), or decompression with interbody fusion. When compared with decompression with PLF, TLIF is the more optimal technique for the management of DS for several reasons.
In a landmark study, Herkowitz and Kurz7 showed that decompression and fusion was superior to decompression alone in a prospective, randomized controlled trial (RCT) of patients undergoing surgical treatment for spinal stenosis with DS. In this study, patients undergoing fusion were much more likely to have satisfactory (96% vs. 44%) results.7 Moreover the fusion patients were >5 times as likely to have an excellent result (44% vs. 8%).7 A subsequent RCT of patients with stenosis and DS demonstrated significantly higher fusion rate with instrumentation (83% vs. 45%).8 Although the 2-year results did not demonstrate a significant difference in outcomes between the instrumented and noninstrumented groups, long-term follow-up of this cohort past 7 years showed a significantly higher rate of excellent and good clinical outcomes (86%) in patients who were fused compared with those with pseudarthrosis (56%).8,9 Furthermore, patients with solid arthrodesis had less back pain and better functional outcomes.9 This high level evidence is the basis for decompression and fusion being the accepted standard of care for the treatment of stenosis in the setting of DS.
As it is well established that patients who achieve solid arthrodesis have better outcomes with long-term follow-up, surgeons should choose the technique that provides a higher fusion. In a prospective multicenter trial, even with instrumentation and iliac crest bone graft, PLF resulted in a 52% fusion rate at 2 years.10 Other authors have reported higher fusion rates over 80% with PLF but with iliac crest bone graft which adds significant surgical morbidity and postoperative pain.8 With use of local autograft or allograft bone, fusion rates seem to be much lower with reports from 50% to 70% in the literature.10,11 In contrast, fusion rates following TLIF are considerably higher with most studies demonstrating fusion rates over 90%.12–14 A recent meta-analysis by Wu et al14 demonstrated a fusion rate of 90.9% for open TLIF and a 94.8% fusion rate for minimally invasive TLIF.