Anatomy and Technique

Anatomically, the sympathetic fibers in the lumbar spine run ventral to the vertebral bodies and thus out of the path of the posterolaterally introduced instruments. The iliac vessels are also anterior to the bodies. The annulus at the site of fenestration is covered only by fibers of the psoas. The spinal nerve is separated from the annulus by a thin layer of fat and fibers of the psoas. The nerve courses anteriorly and caudally after leaving the foremen. It sits anterior to the transverse processes.

The so-called "triangular working zone" is defined as the extrapedicular space allowing safe passage of instruments with the spinal nerve as the anterior boundary, the proximal end plate of the caudal lumbar segment as the inferior boundary, and the superior articular process of the caudal vertebrae as the posterior boundary ⁷ (Figure 17-22).

If one follows the course of posterolaterally introduced instruments, inserted approximately 9 to 10 cm lateral of midline, parallel with the disc space, the nerve is largely covered (and thus protected) by the zygoaphyseal joints, pedicles, and transverse processes. ⁶

A small portion between the foremen and the superior border of the transverse process is vulnerable to penetration; however, this is generally avoided by three techniques. First, through the use of a blunt end trocar, which tends to push the root aside rather than piercing it. Second, through insertion parallel to the disc space. Kambin and Brager ⁶ have shown increased chance of entrance into the neuroforamen when the instruments are angled caudally. Lastly, the endoscope allows direct inspection of the annular fibers immediately prior to use of the fenestrator.

Prophylactic antibiotics are recommended. The patient may be positioned either in the prone or lateral decubitus positions on a radiolucent table. A fluoroscope is positioned perpendicular to the long axis of the spine, allowing perfect anterior-posterior and lateral projections of the disc space under investigation. Anesthesia consists of local skin infiltration superficial to the lumbodorsal fascia, occasionally supplemented by small amounts of short-acting narcotics. It is vitally important that the patient not be overly narcotized, as patient-surgeon communication during the procedure is absolutely essential.

Under fluoroscopic guidance, an 18 gauge needle is introduced into the center of the disc space obliquely, in a posterolateral to anteromedial direction beginning approximately 10 cm lateral to the midline. Preoperative abdominal CT scan through the disc space allows more precise judgment of angle of the approach and avoidance of intraperitoneal puncture (Figure 17-23). Discograms are then carried out at the symptomatic level(s) and at least one asymptomatic level (internal control) to confirm the concordant nature of the pain.

The next steps vary somewhat depending on which endoscopic system one is using, but basically consist of enlarging the needlestick to a puncture large enough to accommodate the trocar. This is accomplished by passing dilators over the guide wire under careful fluoroscopic control. Next, the endoscope is inserted, verifying the position of the trocar within the triangular working zone, as well as visualization of the outer annulus (Figure 17-24 and l7-25). The working channel of the scope is then used to gain entrance to the nucleus through annular fenestration ^6-10 (Figure 17-26).

Alternatively, if a working channel scope is not being employed, the endoscope can be carefully exchanged for manual or automated instruments (i.e., the Nucleotome ®, Surgical Dynamics or the intradiscal shaver, Sofamor-Danek), which then carry out the removal of disc material under fluoroscopic guidance with intermittent endoscopic visualization. Surgical Dynamics has recently introduced a flexible probe (the Endoflex) that provides visualization, aspiration, and cutting capabilities through a single portal (Figure 17-27).

Posterior endoscopic lumbar discectomy is efficient, cost effective, and safe. Hospitalization and recovery time seem to be decreased. The surgeon must be always cognizant of the strict indications and contraindications, as well as exacting surgical technique so that they can experience favorable surgical outcomes and minimize potential complications.

References

1. Deloitte, Touche: Economic Impact of Laparoscopic Surgery, Boston, MA: August 1993. back

2. Hijikata S. Yamagishi N. Nakajama T. et al: Percutaneous diskectomy: a new treatment method for lumbar disk herniation. J Toden Hosp 1975;5:5-13. back

3. Hult L: Retroperitoneal disc fenestration in low back pain and sciatica. Acta Orthop Scand 1951 ;2():342-348. back

4. Kambin F: Arthroscopic microdiscectomy, Arthrosc J arthrosc Relat Surg 1992;8(3):287-295. back

5. Kambin P. ed. Arthroscopic microdiscectomy: minimal intervention in spinal surgery. Baltimore: Williams and Wilkins, 1990. back

6. Kambin, Brager: Percutaneous posterolateral discectomy anatomy and mechanism. CORR 1987;223:145-154. back

7. Kambin P. Gellman H: Percutaneous lateral discectomy of the lumbar spine. A preliminary report. CORR 1983; 174: 127-132. back

8. Kambin P. Sampson S: Posterolateral percutaneous suction-excision of herniated lumbar intervertebral discs: report of interim results, CORR 1986;207:37-43. back

9. Kambin P. Sampson S: Laminectomy versus percutaneous lateral discectomy: a comparative study. Orthop Transactions 1984;8:408. back

10. Kambin P. Schaffer J: Percutaneous lumbar discectomy-review of 100 patients and current practice. CORR 1989;238:24-34. back

11. Matthews HH, Evans MT, Kyles MK, Molligan HJ: Laparoscopic discectomy with fusion. Proceedings of the 9th Annual Meeting of the North American Spine Society, October 1994 p. 63. back

12. Novotney SR, Guyer RD, Regan JJ, Ohnmeis DD: "Laparoscopic assisted anterior lumbar interbody fusion." Proceedings of the 9th Annual Meeting qt the North American Spine Society, October 1994, pp. 61 -62. back

13. Obenchain TG: Laparoscopic lumbar discectomy: case report. J Laparo-Endosc Surg 1991; 1:145- 159. back

14. Obenchain TG, Cloyd D: Outpatient lumbar diskectomy: description of technique and review of first twenty-one cases. Surg Techn Int 1994;2:415-418. back

15. Onik G. Helms C, Ginsberg L, Hoaglund T. Morris J: Percutaneous lumbar diskectomy using a new aspiration probe. AJR 1985;144:1137-114(). back

16. Pier A, Gotz F. Bacher C: Laparoscopic appendectomy in 625 cases: from innovation to routine, Surg Laparosc Endosc 1991;1 :8-13. back

17. Sachs B. Swaitzberg S: Laparoscopic lumbosacral discectomy and interbody fusion technique: early clinical experience. Proceedings of the 9th Annual Meeting of the North American Spine Society, October 1994, p 67. back

18. Scott TR, Graham SM, Flowers JL, Bailey RW, Zucker KA: An analysis of 12,397 laparoscopic cholecystectomies. Surg Laparosc Endosc 1992;2: 191 -198. back

19. Smith L: Enzyme dissolution of the nucleus pulposis in humans.JAMA 1964;187:137-150. back

20. Stein SC: Laparoscopic lumbar discectomy. Proceedings of the 9th Annual Meeting of the North American Spine Society, October 1994, p. 61. back

21. Zucherman J: Instrumented transperitoneal laparoscopic fusion. Proceedings of the 3rd Annual European Spine Meeting: New Frontiers in Spinal Surgery, 1995, pp. 5()-57. back

22. Bruhl W: Complications of laparoscopic and liver biopsy under vision: the results of a survey, Ger Med Monthly 1967;12:31. back

23. Vilardewll P. Seres I, Marti-Vicente A: Complications ol pritoneoscopy-a survey of 1455 examinations. Gastroint Endosc 1968;14: 178. back

24. Phillips J. Keith D, Hulka B. Keith L: Gynecological laparoscopy in 1975. J Reprod Med 1976;16:105. back

25. Motew M, Ivankovich A, Bieniarz. J. Albrecht R. Zahed B. Scommegna A: Cardiovascular effects and acid-base and blood gas changes during laparoscopy. Am J Obst Gynec 1973;115:1002. back

26. Torrielli R. Cesarini M, Winnock S. Cabiro C, Mene J: Hemodynamic changes during celioscopy: a study carried out using thorasic electric bioimpedance. Can JAnaesth 1992;37:46. back

27. Lenz R. Thomas T. Wilkins D: Cardiovascular changes during laparoscopy-studies of stroke volume and cardiac output using impedance cardiography. Anaesthesia 1976;31:4. back

28. Wolf J. Stoller M: The physiology of laparoscopy: basic principles, complications, and other considerations. J Urol 1994; 152:294-302. back

29. Richardson J. Trinkle J: Hemodynamic and respiratory alterations with increased intra-abdominal pressure. J Surg Res 1976,20:401. back

30. Seed R. Shakespeare T. Muldoon M: Carbon dioxide homeostasis during anaesthesia for laparoscopy. Anaesthesia 1970;25:223. back

31. Scott D, Julian D: Observations on cardiac arrythmias during laparoscopy. BrMed J 1972;1:411. back

32. Cimino L, Petitto N. Nardon G. Budillon G: Holter dynamic electrocardiography during laparoscopy. Gastrointest Endosc 1988;34:72. back

33. Jergensen J. Hanel K, Lalak N. Hunt D, North L, Morris D. Thromboembolic complications of laparoscopic cholecystectomy [Letter]. Br Med J 1993;306:518. back

34. Sosa R. Weingram J. Stein B. Lyons J. Poppos D, Bander N. Vaughan E: Hypercarbia in laparoscopic pelvic Iymph node dissection. J Urol [part 2] 1992;147:246A [abstract] 129. back

35. Nunn J: The effects of changes in the carbon dioxide tension, In Nunn's Applied Respiratory Physiology, 3rd ed. London: Butterworth-Heinemann Ltd., 1987, pp. 460 470. back

36. Kalhan S. Reaney J. Collins R: Pneumomediastinum and subcutaneous emphysema during laparoscopy. Cleve Clinic J. Med1990;57:639. back

37. El-Kady A, Abd-el-Razek M: Intraperitoneal explosion during female sterilization by laparoscopic electrocoagulation-a case report. Int J Gynaec Obst 1976; 14:487. back

38. Robinson J. Thompson J. Wood A. Fire and explosion hazards in operating theatres-a reply and new evidence [Letter]. Br J Anaesth 1979;51:908. back

39. McAfee P. Regan J. Zdeblick T. Zucherman J. et al.: The incidence of complications in endoscopic anterior thoracolumbar spinal reconstructive surgery. Spine 1995;20: 1624-1632. back

40. Zucherman J. Zdeblick T. Bailey S. et al.: Instrumented laparoscopic spinal fusion-preliminary results. Spine 1995; 20:2029-2035. back

Fig 17-1. General setup. Note position of arms out of operative field. back

Fig 17-2. General configuration for L3-S1 approach. back

Fig 17-3. Exposure of anterior annulus. back

Fig 17-4. Exposure of left hypogastric vein and left ascending segmental vein at L5 body level. back

Fig 17-5. L4-5 exposure, the left ascending segmental vein. back

Fig 17-6. L4-5 exposure, the left ascending segmental vein hemoclipped. back

Fig 17-7. Cut segmental vein. back

Fig 17-8. Disc removal with straight pituitary rongeur. back

Fig 17-9. Bone plug placement for dowel-type fusion. back

Fig 17-10. Spinetech starting point localizer with unipolar cautery. back

Fig 17-11. Placement of distraction spacer. back

Fig 17-12. Schematic of placement of BAK cage. back

Fig 17-13. Interbody cage placement. back

Fig 17-14. Reaming carried out with distraction spacer in place. back

Fig 17-15. Schematic of bone graft insertion tube in place. back

Fig 17-16. Cages in place. Note bone graft insertion tube. back

Fig 17-17a-b. Schematic of ideal cage placement. back

Fig 17-18. Incisions immediately after cage placement at L5-S1. back

Fig 17-19. Cages in place at L4-5. back

Fig 17-20. AP and lateral x-rays of ideal cage placement. back

Fig 17-21. Example of cage placement pitfall secondary to slightly oblique x-ray beam. back

Fig 17-22. The "triangular safe zone." back

Fig 17-23. CT scan demonstrating precise estimation of angle of approach. back

Fig 17-24. Endoscopic visualization of annular fenestration. back

Fig 17-25. Endoscopic visualization of annular fenestration. back

Fig 17-26. Endoscopic visualization of Nucleotome. back

Fig 17-27. Artist's rendering of Endoflex.