Microscopic versus endoscopic discectomy: a review
Since the advent of minimally invasive techniques, endoscopic spinal surgery has shown significant promise. Ramsey Chammaa and Bob Chatterjee discuss whether endoscopic discectomy can produce results comparable with open surgery.
Conventional open decompression laminotomy via a posterior approach remains the gold standard approach for symptomatic disc herniation that is resistant to conservative measures; however, micro-discectomy has advantages due to a smaller incision, less tissue trauma, and a shorter operative time and hospital stay (on account of greater magnification of the operative field).
Current literature estimates recurrence rates to be between 3 and 13 per cent, although this does not take into account the length of follow-up and its subsequent effect. Survival analysis has been shown to give a more accurate estimation of the true rate of recurrence: 5 per cent at five years and 7.9 per cent at ten years [1].
Long-term studies show that patient satisfaction remains high at ten years after micro-discectomy, as evidenced by long-term McNab and Roland-Morris scores demonstrating success rate of 83 per cent at ten years [2].
Many new techniques have come and gone, but open and micro-discectomy have stood the test of time and remain the standards against which all others are measured; however, since the advent of minimally invasive techniques, endoscopic spinal surgery has shown significant promise and appears to produce results comparable with open surgery.
The evolution of micro-discectomy and endoscopic discectomy
The first description of a ruptured intervertebral disc was made by Rudolph Virchow in 1857. This was followed by the first successful removal of a ruptured disc by Fedor Krause in 1909, the description of which was published in Oppenheim.
Mixter and Barr were the first to perform an open laminotomy and discectomy, and this was published in The New England Journal of Medicine in August 1934.
Grafton Love, a surgeon at the Mayo Clinic, put his twist on the open discectomy technique in 1939 using a keyhole laminotomy to access the epidural space. The era of micro-discectomy was born.
Hijikata et al. performed the first percutaneous discectomy, and this technique was further refined by Caspar & Yasargil employing the microscope [2a].
Kambin published the first discoscopic view of herniation in 1983 and described arthroscopic techniques and equipment for posterior and postero-lateral disc removal via intra-discal access.
In 1992, Mayer and co-workers introduced the technique of percutaneous endoscopic laser discectomy (PELD), heralded as a new surgical technique for non-sequestrated lumbar discs [2b].
In 1994, Hoogland developed the Thomas Hoogland Endoscopic Spine System (THESSYS). The transforaminal endoscopic spine system (TESSYS) was introduced in Germany by Joimax.
In 1996, Matthews wrote about the transforaminal approach, through Kambin’s triangle. The triangle is defined as a right-angled triangle over the dorsolateral disc: the hypotenuse is formed by the exiting nerve root; the base (width) is the superior border of the caudal vertebra; and the height represents the dura/traversing nerve root.
In 1997, Foley & Smith described the micro-endoscopic discectomy (MED), gaining access to the spine from a direct posterior approach.
Yeung developed the Yeung endoscopic spine system (YESS) in 1997.
Literature review
Evidence directly comparing both modalities is limited. Below we summarise the data to hand.
Mayer et al.
Published work by Mayer et al. compared percutaneous endoscopic discectomy with microsurgical discectomy [3]. This randomised prospective study with a two-year follow-up compared two cohorts of patients matched for age, sex, occupation, pre-operative complaints, conservative therapy, disability and symptomatology. Results showed that those who underwent percutaneous endoscopic discectomy had significantly greater resolution of back pain, leg pain and sensory deficit. This cohort of patients also returned to their occupation in 95 per cent of cases, whereas in the micro-discectomy group, only 72.2 per cent of patients returned to their former ocupation.
Teli et al.
Another randomised control trial published by Marco Teli et al. compared three techniques – micro-endoscopic discectomy, micro-discectomy and open discectomy – and followed up 240 patients for two years. There was no statistically significant difference between the groups; however, the incidences of dural tears, root injuries and recurrent herniations were higher in the micro-endoscopic discectomy group. This was also the costliest intervention [4].
Lee et al.
Lee et al. published work comparing the radiologic evaluation of percutaneous endoscopic lumbar discectomy and open micro-discectomy [5]. In this study, 60 patients, matched for sex, age and disc level, were assigned to each treatment arm and followed up for three years. Results showed superior clinical scores in the endoscopic group but without clinical significance. In addition, there was preservation of disc height and foraminal height in the endoscopic group, with the conclusion that the percutaneous endoscopic lumbar discectomy provides a less-invasive technique.
Ruetten et al.
Ruetten et al. published data on full endoscopic interlaminar and transforaminal lumbar discectomy versus conventional microsurgical technique [6]. Their randomised, controlled study followed up 178 patients for two years, and showed equivalent clinical results for both techniques, with no difference in complication rates. The advantage of the endoscopic technique is that it allows for either an interlaminar or transforaminal approach depending on whether the herniation is within the canal (lateral recess) or outside the canal (foraminal).
The full endoscopic technique brings significant advantages with regards to rehabilitation, and less traumatisation, back pain and complications.
D.Y. Lee et al.
Dong Yeob Lee et al. compared percutaneous endoscopic lumbar discectomy (PELD) with open lumbar micro-discectomy (OLM) for recurrent disc herniation [7]. Twenty-five patients underwent PELD, while 29 had OLM. Results at a mean of 31 months showed that operating time and hospital stay were shorter after PELD, complication rates were lower after PELD, back and leg pains were better following PELD, and recurrence rates were lower in PELD (4 per cent versus 10.3 per cent in the OLM group). In addition, there was preservation of disc height after PELD and the procedure was performed under a local anaesthetic.
Rasouli et al.
In 2014, Rasouli et al. published their systematic review of minimally invasive discectomy (MID) versus micro-discectomy/open discectomy for symptomatic lumbar disc herniation [8]. Results showed that minimally invasive techniques – such as percutaneous endoscopic interlaminar or transforaminal lumbar discectomy, transmuscular tubular micro-discectomy and automated percutaneous lumbar discectomy – may be less successful in relieving leg and back pain and may be associated with a higher rate of re-hospitalisation; however, the authors stated that the differences are small and may not be clinically relevant. They went on to suggest a lower risk of surgical site infection (SSI) with MID techniques and a lower hospital stay.
Advantages of endoscopic discectomy in the treatment of lumbar disc herniation
Several papers exist highlighting the merits of endoscopic discectomy in the treatment of lumbar disc herniations. Here we review the data.
Hermantin et al.
Hermantin et al. published their work in a prospective, randomised study comparing the results of open discectomy with those of video-assisted arthroscopic micro-discectomy [9]. Sixty patients were divided into two groups: the first group would undergo an open laminotomy and discectomy (Group 1), while patients in Group 2 would undergo a video-assisted arthroscopic micro-discectomy. Follow-up ranged from 19 to 42 months. Results showed that clinical parameters were similar in both groups; however, the post-operative disability and the need for narcotics were less in Group 2, and patients in this group also returned to work more quickly.
Yeung
Yeung related his seven years of experience with endoscopic spine surgery for lumbar disc herniations [10]. Over this period, he treated 500 patients using the Yeung endoscopic spine system (YESS), incorporating adjuvant therapies such as laser, radiofrequency ablation, chemonucleolysis and intra-operative steroids, as well as performing foraminoplasty and excising sequestered fragments. He reported good-to-excellent results in 86.4 per cent of patients.
Hoogland et al.
Hoogland and colleagues published his data on endoscopic transforaminal discectomy for recurrent lumbar disc herniation [11]. In this prospective cohort of 262 consecutive cases with a two-year follow-up, in 85.71 per cent of cases the reported outcome after surgery was excellent or good, there was a more than five-point improvement in VAS scores for leg and back pain, with only 2.5 per cent feeling unimproved or worse on McNab testing. The recurrence rate was quoted as 4.62 per cent (11/238).
Another series published by Hoogland et al. compared the outcome of transforaminal posterolateral endoscopic discectomy with or without the combination of a low-dose chymopapain: a prospective randomised study of 280 consecutive cases [12]. At the two-year follow-up, Hoogland demonstrated a high percentage of patient satisfaction with posterolateral endoscopic discectomy alone; however, when combined with chymopapain, there was a statistically significant improvement (85.4 per cent versus 93.3 per cent). The recurrence rate similarly reduced with combination therapy (6.9 per cent versus 1.6 per cent). No complications were encountered.
Yeung et al.
Yeung et al. published results on posterolateral endoscopic excision for lumbar disc herniation [13] – a retrospective study of 307 patients assessed at least one year after the index procedure. Surgeon-performed assessments demonstrated satisfactory results in 89.3 per cent of cases, while 90.7 per cent of patients said they would undergo the same procedure again if faced with a similar disc herniation. The combined complication rate was 3.5 per cent. The author suggests that outcomes of endoscopic micro-discectomy appear to be comparable with traditional, open, trans-canal micro-discectomy.
Discussion
Studies have shown, on the whole, that the endoscopic technique can rival the standards set by more traditional methods, by offering a shorter operating time, a shorter hospital stay, a smaller incision, less blood loss, less tissue trauma, a lower requirement for opioid analgesics and a quicker return to work.
The recurrence rates seen for endoscopic discectomy, albeit after short follow-ups, remain within the ranges anticipated with micro-discectomy. The procedure appears to produce favourable results for first time and recurrent disc herniations.
By taking a more posterolateral trajectory, endoscopic discectomy does not defunction the extensor muscles, and if it proves unsuccessful (or the patient experiences a further herniation at another level) it still allows the surgeon to perform a standard micro-discectomy through a posterior midline incision and laminotomy, as this tissue is still virgin.
Patients can be operated on under local anaesthetic, which abolishes the risks of a general anaesthetic and should, by definition, reduce the associated risk of a venous thromboembolic event; however, the shorter operating time has not been clearly documented and in reality is probably not clinically significant in itself. All these objective parameters only hold true for early follow-up, at up to three months, whereas the longer-term results – as evidenced from the more subjective clinical parameters of pain, function and disability – are no better than those set by micro-discectomy.
The disadvantages of the endoscopic technique are the steep learning curve of exacting a new procedure, the high capital costs (a high-definition TV camera, a high-resolution TFT monitor, a dual-screen image intensifier, instruments, irrigation management system and radiofrequency probes for haemostasis) and disposables, plus not all patients are suitable.
The endoscopic technique was primarily intended to use the transforaminal approach (traversing Kambin’s triangle); therefore, by definition, only foraminal and extra-foraminal (far lateral) discs are easily accessible. Although it is possible to access lateral recess disc prolapses, this is a more technically demanding procedure, particularly if the disc is adherent to the dura or root. As foraminal or extra-foraminal discs only constitute 11 per cent of all herniations, the technique is demanding. This may then lead the clinician to widen the indications to warrant its use.
References
Gaston, P. & Marshall, R.W. (2003) Survival analysis is a better estimate of recurrent disc herniation. J. Bone Joint Surg. (Br) 85(4), 535–537
Findlay, G.F., Hall, B.I., Musa, B.S., et al. (1998) 10-year follow up of the outcome of lumbar microdiscectomy. Spine 23(10), 1168–1171
2a. Yasargil, M.G. (1977) Microsurgical operations for herniated lumbar disc. Adv. Neurosurg. 4, 81–2
2b. Mayer, H.M., Brock, M., Berlien, H.P. & Weber, B. (1992) Percutaneous endoscopic laser discectomy (PELD). A new surgical technique for non-sequestrated lumbar discs. Acta Neurochir. Suppl. Wien. 54, 53–58
Mayer, H.M. & Brock, M. (1993) Percutaneous endoscopic discectomy: surgical technique and preliminary results compared to microsurgical discectomy. J. Neurosurg. 78(2), 216–225
Teli, M., Lovi, A., Brayda-Bruno, M., et al. (2010) Higher risk of dural tears and recurrent herniation with lumbar micro-endoscopic discectomy. Eur. Spine J. 19(3), 443–450
Lee, S.H., Chung, S.E., Ahn,Y., (2006) Comparative radiologic evaluation of percutaneous endoscopic lumbar discectomy and open micro discectomy: a matched cohort analysis. Mt Sinai J. Med. 73(5), 795–801
Ruetten, S., Komp, M., Merk, H. & Godolias, G. (2009) Full endoscopic interlaminar and transforaminal lumbar discectomy versus conventional microsurgical technique: A prospective, randomized, controlled study. J. Spinal Disord. Tech. 22(2), 122–129
Lee, D.Y., Shim, C.S., Ahn, Y., et al. (2009) Comparison of percutaneous endoscopic lumbar discectomy and open lumbar micro discectomy for recurrent disc herniation. J. Korean Neurosurg. Soc. 46(6), 515–521
- Rasouli, M.R., Rahimi-Movaghar, V., Shokraneh, F., (2014) Minimally invasive discectomy versus micro discectomy/open discectomy for symptomatic lumbar disc herniation. Cochrane Database Syst. Rev. 4, 9
- Hermantin, F.U., Peters, T., Quartararo, L. & Kambin, P. (1999) A prospective, randomized study comparing the results of open discectomy with those of video-assisted arthroscopic micro discectomy. J. Bone Joint Surg. Am. 81(7), 958–965
Yeung, A.T. (2000) The evolution of percutaneous spinal endoscopy and discectomy: state of the art. Mt Sinai J. Med. 67(4), 327–332
Hoogland, T., Van Den Brekel-Dijkstra, K., Schubert, M. & Miklitz, B. (2008) Endoscopic transforaminal discectomy for recurrent lumbar disc herniation: A prospective, cohort evaluation of 262 consecutive cases. Spine. 33(9), 973–978
Hoogland, T., Schubert, M., Miklitz, B. & Ramirez, A. (2006) Transforaminal posterolateral endoscopic discectomy with or without the combination of a low-dose chymopapain: a prospective randomized study in 280 consecutive cases. Spine. 31(24), E890–897
Yeung, A.T. & Tsou, P.M. (2002) Posterolateral endoscopic excision for lumbar disc herniation: surgical technique, outcome and complications in 307 consecutive cases. Spine. 27(7), 722–731
Authors
Ramsey Chammaa
Ramsey Chammaa is a specialist registrar in Trauma & Orthopaedics on The Royal London Hospital rotation and is now approaching the end of his fourth year of SpR training. His career aspirations lie in spinal surgery, with a particular interest in adolescent deformity correction.
Bob Chatterjee
Bob Chatterjee is a consultant spine surgeon in London. After graduating from Guy’s & St Thomas’ Hospital in 1995, he completed his SHO training rotation in Swindon and Oxford. Bob has a particular interest in degenerative spine surgery, particularly kyphoplasty and minimally invasive discectomy.
