Conventional open surgical techniques for fusion of the lumbosacral spine have a high incidence of long and implant-related complications as well as those associated with the local tissue destruction required for the approach. For this reason they have been supplanted by minimally invasive procedures.
This study describes one of the most recently introduced techniques: the presacral retroperitoneal approach for axial lumbar interbody fusion (presacral ALIF or AxiaLIF). Although this technique was introduced five years ago, as indicated by the authors, few studies have reported its use. It was introduced to avoid the potential major complications of conventional surgery which include ureteral or vascular damage, retrograde ejaculation, impotence, lower limb symptoms related to sympathetic compromise and injury to the bowel.
AxiaLIF, as it is widely known, may be considered to have evolved from four previously described techniques. One technique consists of the paraxial introduction of a rib strut graft through the sacrum to the L5-S1 interspace or the L5 or L4 vertebrae.1 Another technique involves an open paraxial approach, using fibular strut grafts,2,3 particularly for treatment of spondylolisthesis. A third technique involves introducing a midline cage for L5-S1 fusion through a sacral laminectomy;4,5 and a fourth involves L5-S1 fusion, through posterolateral approach.6
In this prospective cohort study the authors examine the safety and effectiveness of this relatively new technique. It is truly tissue sparing as it maintains the lumbosacral supporting musculotendinous anatomy, with the biomechanical advantages of retaining the integrity of the annulus fibrosus. This is well described in the paper. It also avoids interference with neural elements. Since all cases were enhanced with posterior stabilisation as recommended with other interbody fusion techniques, this paper cannot provide evidence as to the effectiveness of the procedure as a stand-alone instrumentation.
In order to maximise the benefits of this approach we have to consider its complications. A serious complication is injury to the bowel.7 There are no large prospective studies reporting the true incidence. Our knowledge comes from a case report and various presentations in scientific meetings. At this time the only detailed information may be found in 68 reports filed to the FDA8 from 11.187 cases performed worldwide (Trans1 Inc., Wilmington NC)9 giving an incidence of 0.6%. According to these files, for late diagnosis, which is the most frequent form of presentation, a temporary diverting colostomy is the recommended treatment, whereas primary colonoscopic repair is recommended for those patients who present with this complication in the early post-operative period. In my own practice, I address this problem, firstly by selecting patients who do not have a history which predisposes them to the formation of retroperitoneal and perirectal fibrosis, and secondly, by using a similar technique for accessing the anatomical structures, as the authors recommend, and by performing a finger rectal examination followed by fluoroscopy of the terminal bowel with radio-opaque enema (gastrographin) at the completion of surgery. Others recommend proctoscopic examination.
The authors of this paper have made a major contribution in two important areas that needed clarification. The first concerns tips for the safe dissection of the retroperitoneal space in order to prevent injury to the bowel and the second concerns the rate of fusion.
With an adequate methodology for the assessment of the fusion mass, the authors demonstrated that the rate of fusion using this approach is comparable to that using conventional or minimally invasive interbody approaches (ALIF, PLIF, TLIF). One major disadvantage, however, is the fact that this rate of fusion cannot be considered indisputable.
Now that the effectiveness and safety of AxiaLIF has been established, it remains for this technique to be tested and compared with other forms of interbody in a large multicenter prospective randomised study. As AxiaLIF by itself is quick and bloodless surgery, it should be further evaluated as a stand-alone procedure.
In conclusion, although this paper does not represent a very rigorous scientific study telling us whether this technique is safer and more effective than other forms of lumbosacral fusion, it is, nevertheless, a truly tissue sparing, minimally destructive, technique for achieving fusion at the lower two levels of the lumbosacral spine, and therefore, a useful contribution to the armamentarium of spine surgeons.
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5. Bartolozzi P, Sandri A, Cassini M, Ricci M. One-stage posterior decompression-stabilization and trans-sacral interbody fusion after partial reduction for severe L5-S1 spondylolisthesis. Spine 2003;11:1135-41.
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7. Botolin S, Agudelo J, Dwyer A, Patel V, Burger E. High rectal injury during trans-1 axial lumbar interbody fusion L5-S1 fixation: a case report. Spine 2010;35:E144-8.
8. MAUDE, Adverse Event Report, 2010 Oct; F.D.A complication website http//:www.Accessdata.fda.gov/scripts/cdrh/scfmaude/TextResults.cfm).
Professor A Hadjipavlou
University of Crete, Crete, Greece