over the next 4 decades , several anterior transperitoneal and retroperitoneal approaches to the lumbosacral spine were described . minimally invasive techniques to alif began in 1991 as obenchain first described a noninstrumented l5-s1 discectomy . zucherman et al in 1995 reported the first series of laparoscopic alif with threaded interbody metallic cages . over the next several years , more reports of laparoscopic alif surfaced . mcafee et al demonstrated the feasibility and safety of endoscopic thoracolumbar fusion in a prospective multicenter study . technology has rapidly advanced with respect to inter - body devices from bone dowel alif to metal threaded bak ( spinetech ) and ray ( surgical dynamics ) cages to the lordotic lt cage ( medtronic ) . arthrodesis materials have also progressed from autogenous bone graft to the use of rhbmp-2 thus improving fusion rates . a retrospective review of patients who underwent laparoscopic l5-s1 anterior interbody fusion by a laparoscopic general surgeon ( ctf ) and orthopedic surgeon ( fmp ) over a 5-year period ( 1998 to 2003 ) was performed . patients with chronic mechanical lower back pain secondary to degenerative disc disease , spondylolisthesis , or post - laminectomy syndromes were candidates for alif . patients underwent magnetic resonance imaging ( mri ) , provocative discography , or both , preoperatively to identify the symptomatic disc level . since cages were placed , cefazolin ( 1 g to 2 g iv ) was given with the induction of anesthesia . an infraumbilical curvilinear incision was used to place a hasson trocar followed by pneumoperitoneum maintained at 15 mm hg . three additional trocars 10 cm to 11 mm were introduced under direct view ; one in the right side ipsilateral to the umbilicus , one in the right lower quadrant ; and one in the left lower quadrant . the 18-mm trocar , which is the main working port for the spinal surgeon , was placed in the suprapubic midline region ( figure 1 ) . the patient was then placed in a steep trendelenburg position to facilitate cephalad retraction of the viscera . the sigmoid colon was retracted to the left by using an inflatable balloon retractor ( soft wand retractor , acmi , san jose , ca ) introduced through the left lateral port . hook electrocautery was then inserted through the right lower quadrant port , and the peritoneum at the root of the recto - sigmoid mesocolon was opened below the bifurcation of the aorta . using blunt dissection , the medial sacral artery and vein were identified and ligated with placement of vascular clips . at this point , the l5-s1 intervertebral disc was exposed , and the right and left iliac veins were mobilized by using a palpation probe . exposure to the l5-s1 was maintained with the inflatable balloon retractor , the sigmoid mesocolon was retracted to the left to give adequate exposure to this area and the orthopedic portion of the procedure was initiated . a k - wire was then percutaneously passed from a midline suprapubic position into the diseased disc space . fluoroscopy confirmed placement into the l5-s1 disc space and allowed correct angulation of the suprapubic 18-mm working trocar ( figure 1 ) . the annulus over the disc space was divided , and the disc evacuated with a trephine and rongeurs until bleeding cancellous bone was exposed . a dilator and a distraction plug were driven into the interspace to restore the native disc space height and distract the vertebral bodies before the disc reaming and cage placement . bak ( spinetech , minneapolis , mn ) or ray ( surgical dynamics , norwalk , ct ) cages were used until may 2001 ; thereafter , lordotic lt ( medtronic , minneapolis , mn ) cages were used ( figure 2 ) . iliac bone graft was used to fill the cages until the end of 2001 ; thereafter , recombinant human bone morphogenetic protein-2 ( rhbmp-2 ) ( infuse , medtronic , minneapolis , mn ) was used . the posterior peritoneum was left open initially in this series but was reapproximated after a case of small bowel adhesion to the cage . at the completion of the arthrodesis , the fascial defects at the trocar sites were closed using a fascial closer . in some cases , percutaneous posterior pedicle screw placement was performed with the sextant ( medtronic , minneapolis , mn ) system . a clear liquid diet was begun with passage of flatus and advanced to a regular diet as tolerated . the patient was placed on patient - controlled analgesia postoperatively and weaned to oral narcotic analgesics . patient was discharged when they had an adequate oral intake and pain was controlled on oral analgesics alone . follow - up consisted of clinic appointments at 1 week , 1 month , 3 months , and yearly thereafter . visual analogue scale scores for spinal pain were recorded preoperatively and at 1 year postoperatively . the fusion was deemed healed if there was absence of motion across the operated level and the implant remained stable without surrounding radiolucencies or evidence of bone bridging the interspace . diagnostic studies such as mri were ordered during follow - up if a patient developed new symptoms . five patients had undergone prior discectomy ( n=3 ) , laminectomy ( n=1 ) , or fusion ( n=1 ) . the presenting symptoms were back pain in all patients , sciatica in 5 patients ( 18% ) , and buttock pain in 1 patient . the mean duration of surgery was 22547 minutes ( range , 137 to 309 ) . the average operative time was significantly longer ( p<0.008 , mann - whitney ) in the first 19 patients of the series who had graft from the iliac bone utilized ( 24142 minutes ) versus the last 9 patients in whom rhbmp-2 was used ( 19039 minutes ) . four patients ( 14% ) could only undergo unilateral cage placement secondary to either difficulties achieving adequate purchase with 2 cages or vessel encroachment limiting access for bilateral cage placement . the first 3 of these patients underwent subsequent posterior screw fixation being discharged on day 15 , 5 , and 4 , while the last underwent concomitant posterior screw fixation and was discharged on day 3 . intraoperative complications included 2 bladder injuries sustained secondary to k - wire guide pin localization . urinary catheters were maintained until postoperative day 4 at which time a negative cystogram allowed removal . three patients ( 10% ) had prolonged postoperative ileus that delayed discharge until day 15 ( patient also had a delayed secondary procedure for posterior instrumentation ) , 6 , and 5 . the length of stay ( los ) for all patients was 4.12.4 ( range , 2 to 15 ) . mean los was 5.2 days in the first 19 patients versus 3.61 days in the last 9 ( p=0.43 , mann - whitney ) . one patient developed displaced bone dowel cages with symptomatic radiculopathy one week after discharge from the hospital . this patient underwent reoperation with posterior pedicle screw instrumentation . a second patient sustained a fall while in the hospital on the third postoperative day and developed acute radiculopathy with ehl weakness . computed tomography revealed the cages to be slightly laterally positioned extending toward the neural foramen on the symptomatic side . the patient underwent hemifacetectomy , annular excision , foraminotomy and posterior translaminar screw placement . a third patient developed buttock pain 6 months postoperatively . the small bowel was adhered to the cage , and a small bowel resection was required . visual analog scores ( vas ) were significantly improved from 8.60.8 before surgery compared with 2.80.8 ( p<0.0001 , wilcoxon matched pairs ) at 1 year following surgery ( figure 3 ) . since the first report of laparoscopic anterior interbody fusion in 1991 , several retrospective reviews and prospective trials have emerged . l4-l5 laparoscopic alif is associated with a higher morbidity rate than the open approach , and many authors have ceased performing l4-l5 laif after encountering adverse complications and high conversions rates . the junction of the left iliac vein and the vena cava often lies directly over the l4-l5 disc space making the laparoscopic approach very difficult and may lead to life - threatening vascular injury . laparoscopic l4-l5 alif was compared with a mini - retroperitoneal open technique by zdeblick and david who concluded that there did not appear to be a benefit to the laparoscopic approach because they encountered a morbidity rate of 20% . they advocated laparoscopic l4-l5 alif only if the bifurcation of the great vessels is above the l4-l5 disc space . as a result of the above although both senior authors ( ctf and fmp ) have extensive prior laparoscopic experience , this series emphasizes the learning curve associated with laparoscopic alif . mean operative time decreased progressively over the course of this study from 24142 minutes for the first 19 patients to 19039 minutes for the last 9 . the learning curve is known to be steep with laparoscopic alif , and we feel that operative times would likely continue to decrease as further experience is gained . we were initially concerned that 3 patients underwent reoperation ( 10.7% ) early in our experience . one patient had a displaced bone dowel 1 week postoperatively and required posterior fusion and screw placement . two other patients developed radiculopathy postoperatively ( 3 days and 6 months ) and underwent foraminotomy with hemifacetectomies to decompress the involved nerve roots and posterior instrumented fusion . all 3 of these cases occurred early in our experience reflecting errors in technique , and no cases occurred of postoperative radiculopathy in the last 20 cases . kuslich et al reported that 8.7% of patients required a second operation after open bak cage placement . ten patients ( 36% ) underwent posterior screw placement to provide additional support to the alif . in 4 of these patients , posterior instrumentation was placed because of the inability to place 2 interbody cages secondary to vessel encroachment or inability to gain acceptable bony purchase with both cages . in the remaining 6 cases undergoing posterior stabilization , posterior pedicle instrumentation had been deemed necessary preoperatively to provide additional support to the alif construct . we feel that posterior pedicle screw placement in a minimally invasive fashion should be used liberally to achieve stability particularly in those cases of unilateral cage placement . the first 2 patients who underwent delayed screw placement had an los of 5 and 15 days while the last patient who underwent concomitant screw placement had an los of 3 days . therefore , concomitant placement of the screws with the alif will likely decrease hospital stay in those cases of unilateral cage placement . one reason that los appears to be longer than that in some reports is that a liquid diet was not initiated until flatus occurred . immediate postoperative advancement of the diet and quicker weaning off narcotics would likely have decreased los . patients who undergo laparoscopic procedures tend to have a decreased length of postoperative ileus and length of stay compared with those who undergo an open procedure , but recent studies have shown no difference . the availability of rhbmp-2 has eliminated the need for iliac bone graft and a separate incision . a prospective study of laif with rhbmp-2 by kleeman et al revealed a 100% fusion rate at 6 months . closure of the peritoneum over the metallic cages particularly when rhbmp-2 is used appears to be important because we did have one patient who developed a small bowel obstruction secondary to adhesive disease and required a small bowel resection . we attribute the good results of this study to 3 factors : patient selection , advanced laparoscopic experience of both the general and the spine surgeon , and the presence of both surgeons during the entire procedure . laparoscopic l5-s1 alif can be performed safely with low morbidity with the inherent advantages of minimally invasive surgery .
objective : we evaluated our experience with laparoscopic l5-s1 anterior lumbar interbody fusion ( alif).methods : this represents a retrospective analysis of consecutive patients who underwent l5-s1 laparoscopic alif between february 1998 and august 2003.results:twenty-eight patients underwent l5-s1 laif ( 15 males and 13 females ) . 
 the mean age was 43 years ( range , 26 to 67 ) . 
 mean operative time was 225 minutes ( range , 137 to 309 minutes ) . 
 no conversions to an open procedure were necessary . 
 twenty - four ( 85.7% ) patients underwent successful bilateral cage placement . 
 four patients ( 14.3% ) in whom only a single cage could be placed underwent supplementary posterior pedicle screw placement . 
 mean length of stay ( los ) was 4.1 days ( range , 2 to 15 ) . 
 two patients underwent reoperation subacutely secondary to symptomatic lateral displacement of the cage . 
 one patient developed radiculopathy 6 months postoperatively and required reoperation . 
 one patient developed a small bowel obstruction secondary to adhesions to the cage requiring laparoscopic reoperation . 
 fusion was achieved in all patients . 
 visual analogue scale scores for back pain were significantly improved from 8.60.8 to 2.80.8 ( p<0.0001 ) at 1 year.conclusion:l5-s1 laif is feasible and safe with all the advantages of minimally invasive surgery . 
 fusion rates and pain improvement were comparable to those with an open repair .