Anterior Lumbar Interbody Fusion Followed by Percutaneous Pedicle Screw Fixation for Lytic Spondylolisthesis

 

Sang-Ho Lee, MD, Ph.D, Won Gyu Choi, MD, Sang-Rak Lim, MD.

Wooridul Spine Hospital

 

 

Introduction

 

Spondylolytic spondylolisthesis is one of the common lumbar spinal disorders, which display symptoms characteristic of both spinal instability and stenosis.

There are several surgical options such as anterior lumbar interbody fusion (ALIF) alone, ALIF followed by decompressive laminectomy and pedicle screw fixation (PF), posterolateral fusion with pedicle screw fixation, and decompressive laminectomy, posterior lumbar interbody fusion (PLIF) and/or Posterolateral Fusion with Pedicle Screw fixation.

ALIF alone with threaded fusion cage such as TFC, and BAK is not sufficient to fix the unstable segment due to posterior arch defect. Posterolateral fusion in situ without decompression is not sufficient to relieve neurogenic leg discomforts.

 Posterior laminectomy followed by fusion with PF is generally considered to provide the highest level of stability as well as decompression. It may be the most common and standard surgical procedures to treat grade 1-2 lytic spondylolisthesis.

However, the procedures require wide dissection of normal tissue and excessive neural retraction, which cause increased blood loss, intraspinal neural injury, increased postoperative pain and recovery time.

If we do not perform posterior laminectomy to remove fibrotic soft or hard tissues around isthmic defect, the leg symptoms will continue?  We tried anterior reduction and anterior decompression by removal of bulged posterior annulus through anterior approach to relieve leg claudication and pain. We augmented the ALIF with percutaneous pedicle fixation (PPF).

The purpose of this investigation was to evaluate the outcome of the minimally invasive ALIF (MINI-ALIF) followed by percutaneous pedicle screw fixation without posterior decompressive laminectomy for grade 1-2 spondyolytic spondylolisthesis.

 

 

Materials and Methods

 

This was a retrospective review of 25 patients with lytic spondylolisthesis undergoing minimally invasive ALIF followed by percutaneous pedicle screw fixation. All of them were treated with various lumbar interbody cages between Jan. 2000 to Feb. 2001.

No posterior laminectomy and no posterior or posterolateral fusion were performed. There were 5 males and 20 females. Mean age was 49 (range 26-69). 21 patients had grade 1 and 4 patients had grade 2 lytic spondylolisthesis. All the patients had suffered from low back pain and referred or radiating leg pain during walking or standing. Average duration of symptoms were 24 months (range 3- 120 mos).

The surgical technique were minimally invasive endoscopic assisted midline retroperitoneal ALIF under 4 to 5 cm skin incision followed by percutaneous pedicle screw fixation under 2 cm skin incision for each pedicle. Mean duration of operating time was 197 min (range 160-375). The time for ALIF was 90 min. The operating time for PPF was 107 min. Mean blood loss was 150 cc (range 70-240cc).

Mean hospital stay was 8 days (range 5-13 days). 24 patients underwent one –level segment fusion between L4-L5 (9 patients) and between L5- S1 (15 patients). One patient had two segmental fusion lesions on L4, L5 and S1 level.

Postoperative plain X-rays and CT scan were taken for all patients to analyze and determine the placement of pedicle screws and the degree of reduction of spondylolishesis.

 

 

Results

 

Clinical successful results according to Macnab’s criteria showed excellent outcome in 11 patients (44 %), good outcome in 13 patients (52%), fair in one patient, and no poor patient. Slippage of the preoperative spondylolisthesis was mostly corrected in all cases, which were confirmed radiologically by plain X- ray, CT and MRI.

There were no complications except two cases. In the two cases, the lateral cortical walls of the vertebral body were broken by the screws during slippage reduction and were intraoperatively repaired with bone cement and screws were re-inserted with some adjustments making a sound purchase. One screw violation of the inferior pedicle wall in an osteoporotic patient, which was noted intraoperatively, was left because of the possibility of the screw loosening. All but one patient could get out of bed with a brace soon after the operation on the postoperative 1st day. The one patient had considerable postoperative knee pain, believed to be caused by excessive reduction of L4/5 grade 2 spondylolisthesis. The knee pain gradually diminished over a period of one month.

 Preoperative leg symptoms were reduced considerably immediately after the operation, although surgical back pain persisted for a much longer period of time. Besides the postoperative complications, there were pains in the iliac bone graft site in all cases.

 

 

Discussion

 

Disadvantages of posterior decompression and fusion are wide dissection of normal tissue, excessive neural retraction, increased blood loss, neural injury and fibrosis, and increased postoperative pain and recovery time. Posterior lumbar interbody fusion (PLIF) may cause neurological complications. Cloward⑵ reported four patients with foot drop out of 93. Lin⑸ reported 25 patients with neurologic deficit out of 465. Fraser⑷ described cauda equina lesions as a result of PLIF due to thecal sac retraction. Ohkochi⑹ reported 10 years follow-up study of PLIF and noticed 25% of the patients had accelerated degeneration in the adjacent segments. Brodke⑴ said that once PLIF is performed the potential for revision surgery is extremely low. If the patient with PLIF does not experience a good outcome, he or she has little recourse.

 The advantage s of mini-ALIF with PPF without posterior decompression for lytic spondylolisthesis are no back muscle injury, no abdominal muscle injury, no blood transfusion, no epidural scar due to no touch of dural sac, anterior decompression of bulged annulus, minimal postoperative pain and early discharge. Disadvantages of mini-ALIF with PPF are impossibility of posterior decompression and limited indication. Dynamic Low back and dynamic claudication of legs due to grade 1 or 12 spondylolisthesis is excellent indication for Mini-ALIF with PPF.

 

 

Conclusion

 

Spondylolytic spondylolisthesis grade 1-2 can be treated with mini-ALIF and PPF without using a posterior neural decompressive procedure. PPF not only has the advantages of minimally invasive surgery, but is not inferior to open conventional screw fixation in terms of accuracy of the screw placement, reduction of slippage, and manageability of intraoperative complications such as cortical bone breakage.

 

 

References

 

  1. Brodke DS, Dick JC, Kunz DN, MxCabe R, Zdeblick TA. Posterior lumbar interbody fusion a biomechanical comparison, including a new threaded cage, Spine 1997;1;26-31
  2. Cloward RB. Spondylolisthesis : Treatment by laminectomy and posterior interbody fusion. Clin Orthop 1981;154:74-82
  3. Choi WG, Lee SH. Percutaneous pedicle screw fixation as augmenter of minimally invasive Anterior lumbar interbody fusion. Presented at Seattle in NASS, Nov. 2001.
  4. Fraser RD. Interbody, Posterior and Combined Lumbar Fusions. Spine 1995; 20:167S-177S.
  5. Lin PM, Cautilli RA, Joyce MF. Posterior lumbar interbody fusions. Clin Orthop 1983; 180:154-168.

6.      Ohkohchi T, Yamamoto T, Ohwada T, Kudawara I, Horiki M. Longterm follow-up study of posterior interbody fusion for degenerative spondylolisthesis. Presented at the annual meeting of the European Spine Society, Zurich, Switzerland, October 19, 1996.

 

 

Figure 1. Retroperitoneal mini-ALIF was done through 4cm midline incision with assistance of endoscopic ballooning and robotic retractor.

 

Figure 2. This 45 year-old female with severe neurological claudication on both legs had lytic spondylolisthesis on preoperative lateral view of plain X-ray and MRI.

 

Figure 3. Postoperative radiographs show no laminectomy, good reduction of slippage and increased disc height. 2cm skin incision was shown for the each pedicle screw.

 

Figure 4. Postoperative CT showed good position of pedicle screws through percutaneous procedures without muscle retraction.