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Minimally invasive spine surgeries (MISS) since its inception around 15 years ago has undergone rigorous changes with ever evolving technologies. Minimally invasive spine surgeries with “percutaneous” …

Minimally invasive spine surgeries (MISS) since its inception around 15 years ago has undergone rigorous changes with ever evolving technologies. Minimally invasive spine surgeries with “percutaneous” and “tubular” approaches is based on novel concept of minimizing collateral soft tissue damage, while achieving surgical goal in various spinal pathologies. MISS has been applied to simple spinal procedures of discectomy, decompression and fusion to even complex surgeries like deformity correction. MISS vis a vis “conventional open techniques” has benefits in terms of postoperative pain, concurrent tissue damage, disruption of spinal stabilizing structures, estimated blood loss, need of blood transfusion, length of hospital stay, surgical site infections, time to ambulation and functional recovery.

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  • 1. Minimally invasive spine surgeries (MISS)
  • 2. Apollo Medicine 2012 December Volume 9, Number 4; pp. 307e311 Theme Symposium Minimally invasive spine surgeries (MISS) Ashish Jaiswal* ABSTRACT Minimally invasive spine surgeries (MISS) since its inception around 15 years ago has undergone rigorous changes with ever evolving technologies. Minimally invasive spine surgeries with “percutaneous” and “tubular” approaches is based on novel concept of minimizing collateral soft tissue damage, while achieving surgical goal in various spinal pathologies. MISS has been applied to simple spinal procedures of discectomy, decompression and fusion to even complex surgeries like deformity correction. MISS vis a vis “conventional open techniques” has benefits in terms of postoperative pain, concurrent tissue damage, disruption of spinal stabilizing structures, estimated blood loss, need of blood transfusion, length of hospital stay, surgical site infections, time to ambulation and functional recovery. However MISS is associated with steeper learning curve, poorer surgical orientation, higher peroperative ionizing radiation to patient and surgical team, higher incidence of incidental durotomies, dependency on technology, and higher upfront cost of treatment. Copyright © 2012, Indraprastha Medical Corporation Ltd. All rights reserved. Keywords: Minimally invasive, Spine surgeries, Tubular, Percutaneous INTRODUCTION Minimally invasive spine surgeries (MISS) are based on concept of decreased concurrent tissue damage while performing index procedures in spine for treating various spinal pathologies. The purported advantages of minimally invasive spine surgery are less blood loss, lesser surgical morbidity, need of blood transfusion, lesser postoperative analgesic requirement, less hospital stay and early rehabilitation with functional resumption.1e6 Minimally invasive spine surgery has come a long way since its inception. There has been constant endeavor to minimize the collateral surgical damage while achieving the surgical goal. There have been many revolutions in this field including introduction of microscopes, endoscopes, specialized tubular and expandable retractors. Availability of better instrumentation has facilitated the minimization of surgical approach. MISS is commonly applied in various common spinal procedures like discectomies, decompression and fusion. With time the applications of MISS is expanding to include even complex surgeries like spinal deformity correction. MUSCLE PRESERVATION e THE KEY CONCEPT IN MISS It is known that traditional open approaches to spine surgery lead to increased paraspinal muscle injury following denervation, ischemia secondary to prolonged retraction and detachment of musculotendinous junction. Denervation and ischemia can result from direct injury to dorsal roots and vasculature in extensive surgical exposure, and also occurs due to increased intramuscular edema and resultant focal compartment syndrome secondary to prolonged strong retraction. This has a clinical implication in the form of increased postoperative backache. The major advantage of MISS is preservation of paraspinal musculature especially multifidous insertion in spinous process.7 Senior Consultant, Department of Orthopaedics and Spine Surgery, Apollo Hospitals, Seepat Road, Bilaspur, Chhattisgarh 645009, India. * Corresponding author. Tel.: þ91 9630005676, email: drashishjaiswal@yahoo.com Received: 3.9.2012; Accepted: 24.9.2012; Available online 4.10.2012 Copyright Ó 2012, Indraprastha Medical Corporation Ltd. All rights reserved. http://dx.doi.org/10.1016/j.apme.2012.09.003
  • 3. 308 Apollo Medicine 2012 December; Vol. 9, No. 4 Disruption of the midline supraspinous and interspinous ligament complex in conventional open approaches can lead to loss of tension band and thus can result in late postoperative instability. MISS avoids the loss of integrity of this midline supraspinous/interspinous complex which in addition to providing structural stability to spine, also acts as a tie beam for effective functioning of paraspinal muscles.2 Moreover, less muscle disruption in MISS also leads to decreased blood loss and lesser surgical stress response. MINIMALLY INVASIVE LUMBAR DISCECTOMIES Lumbar discectomy has undergone a radical change in approach since its first description by Mixter and Barr using laminectomy in 1934. Progressively, it was noted that the goal of discectomy and decompression is achievable with lesser invasive approaches. Introduction of use of microscope for discectomy by Yasargil and Caspar revolutionized this procedure and still microdiscectomy is considered as a “gold standard”. MISS was described by Foley and Smith in 1997 for discectomy using tubular retractors. This relies on dilating the way through muscle fibers rather than stripping it from lamina and spinous process. Endoscope or microscope can be used as an adjunct for visualization. Many spine surgeons prefer using microscope owing to 3-Dimensional visualization and also, as most of them are already acquainted with use of microscope, while with endoscope, it has limitation of 2-Dimensional vision and one needs an additional skill to master due to unfamiliarity. However superiority of MISS over microdiscectomy is debated by some as, in microdiscectomy, already there is a minimal surgical exposure and long term results of both the approaches have been found to be similar.6 Adequate decompression, regardless of the operative approach used, may be the primary determinant of radicular pain relief. Adversely, it has been noted that there is a higher of incidental durotomy in minimally invasive discectomy8 with possible explanation being limited visualization, poor depth perception and steep learning curve. Some argue that microdiscectomy can itself be considered as a minimally invasive procedure for discectomy and controversy persists whether to stick to age old microdiscectomy or to adopt tubular discectomy where again, even an experienced spine surgeon needs to tide over a steep learning curve. However, MISS seems to be more beneficial for spinal procedures with extensive surgical exposure and soft tissue disruption like spinal instrumentation and fusion.4,5,9,10 It can be argued that discectomy is the most common surgery in spine, hence one should master MISS for discectomy before graduating to more extensive procedures with MISS. Minimally invasive Jaiswal discectomy has an advantage in morbidly obese patients where surgical exposure through tubular retractor is better attained than with conventional retractors used in micro discectomy.6 Percutaneous transforaminal endoscopic discectomy under local anesthesia is another way of doing MISS for discectomy. Yeung and Hoogland are credited for the development of the Yeung Endoscopic Spine System (YESS) in 199711 and the Thomas Hoogland Endoscopic Spine System (THESSYS) in 1994, respectively.12 The purported advantages are avoidance of general anesthesia, smaller skin incision, conduction as a day care surgery and intraoperative active feedback of patient about alleviation of radicular symptoms. However, it is not without limitations, being applicable for specific types of disc herniations and necessitates even steeper learning curves. Superiority of percutaneous techniques over conventional microdiscectomy still remains unclear as similar outcomes has been demonstrated with both methods. MINIMALLY INVASIVE TRANSFORAMINAL LUMBAR INTERBODY FUSION Lumbar fusion is commonly done for spinal instability or deformity resulting from spondylolisthesis or scoliosis as well as low back pain from degenerative disc disease refractory to conservative treatment. Interbody fusion is the most preferred approach for lumbar fusion as it facilitates larger surface of fusion bed, opening up of neural foramen through “jack up effect” and additional anterior stability when a cage is placed. Currently, transforaminal lumbar interbody fusion (TLIF) is most commonly performed for lumbar arthrodesis, as TLIF provides exposure of the disc space while requiring less dural and nerve root retraction. However in traditional open approach TLIF requires extensive surgical exposure. The iatrogenic injury of muscle and soft tissue is an important cause of postoperative low back pain which might even counteract the effects of surgery and sometimes labeled as “fusion disease.” MISS transforaminal lumbar interbody fusion using nonexpendable or expandable tubular retractor and bilateral percutaneous screw placement reduces such collateral soft tissue damage and has shown to produce favorable outcomes in respect to postoperative back pain, total blood loss, need for transfusion, length of hospital stay, time to ambulation and functional recovery.4,5 Iliac crest autograft remains the gold standard, with the osteogenic, osteoinductive, and osteoconductive components required to achieve fusion, but it comes with associated donor site morbidity. Majority of spine surgeons use locally harvested bone from bony decompression as a graft to avoid donor site morbidity. However in MISS transforaminal
  • 4. Minimally invasive spine surgeries (MISS) interbody fusion when the amount of local graft is inadequate or even otherwise allograft or bioactive agent like recombinant human bone morphogenetic protein (rhBMP2) can be added to facilitate fusion. MINIMALLY INVASIVE DECOMPRESSIONS IN LUMBAR CANAL STENOSIS Lumbar canal stenosis (LCS) is a common degenerative process among the elderly leads to progressive neurogenic claudication and often needs surgical decompression to alleviate the associated symptoms and disability. Indeed, LCS is the most common indication for surgery of the spine in patients over the age of 65 years. Conventionally lumbar laminectomy was indicated surgical procedure for LCS. However with advances in noninvasive imaging especially MRI, it was noted that most of these pathologic compressive changes typically occur at the level of the interlaminar window, hence it seems more prudent to do focal decompression at level of compression rather than wide laminectomy. The ultimate goal, regardless of the technique used, is to perform an effective decompression of the affected thecal sac and nerve root. Current MISS techniques for decompression avoids collateral damage and have successfully shown to shorten hospital recovery times, reduce intraoperative complications, and minimize soft tissue trauma with resultant decrease in surgical stress response which is a crucial factor in consideration in elderly patients.1e3 There has been constant endeavor to adopt a minimally destructive method to attain aimed surgical neural decompression in lumbar canal stenosis. Various methods of less invasive approaches namely spinous process splitting approach, bilateral laminotomies, bilateral decompression via unilateral laminotomy etc has been described. MISS for lumbar canal stenosis using tubular retractors aided by endoscope or microscope has been employed successfully to treat LCS.1e3 However, limitation of MISS in LCS decompression is that it may fail to provide an adequate decompression in patients with bony foraminal stenosis. In patients with lumbar stenosis in the setting of spondylolisthesis, scoliosis, or severe degenerative disc disease, the inherent destabilizing nature of posterior decompression, even using MISS, may warrant a fusion operation in addition to decompression.3 MINIMALLY INVASIVE FIXATIONS IN THORACOLUMBAR TRAUMA Conventional spine exposures add to pre-existing paraspinal soft tissue injury secondary to trauma in spinal injuries. Theme Symposium 309 MISS has a potential to reduce the approach-related morbidity associated with conventional techniques which is even more crucial in setting of pre-existing injury. However MISS has limited indications in thoracolumbar injuries. Pure osseous injuries like bony chance fractures are ideally suited for MISS fixations where one can do away without bone grafting and decompression.9 Fixation in such a pure osseous injury has further advantage of possibility of implant removal with restoration of spinal mobility.9 Spinal fractures needing decompression may be fixed with percutaneous instrumentation and decompression can be achieved with expandable tubular retractors or anterior laproscope/thoracoscopic decompressions.10 However one has to conversant with all the procedures and carefully select fractures types amenable for such MISS interventions. Specific clinical indications for MISS interventions in spinal fractures are still evolving. Percutaneous vertebroplasty and kyphoplasty are minimally invasive procedures when performed in symptomatic osteoporotic vertebral fractures provides dramatic pain relief to patients who are not responding to conservative care.13 Vertebroplasty entails the percutaneous injection of bone cement into the fractured vertebra, while kyphoplasty addresses pain and kyphotic deformity by the percutaneous expansion of an inflatable bone tamp to effect fracture reduction before cement deposition in a fractured vertebra. SUMMARY Although the authoritative definition of minimally invasive spine surgery remains elusive, the one proposed in summary statement published by McAfee et al14 looks most apt. “An MISS is one that by virtue of the extent and means of surgical technique results in less collateral tissue damage, resulting in measurable decrease in morbidity and more rapid functional recovery than traditional exposures, without differentiation in the intended surgical goal.” Growing experience with MISS techniques by operating surgeons and development of newer instrumentation by manufactures are now enabling an increasingly large portion of spine surgical procedures to be performed via minimally invasive techniques. Extensive tissue trauma in traditional surgical exposures cause exaggerated surgical stress response and leads to variety of complications like deep venous thrombosis, pulmonary embolism, pulmonary atelectasis, pneumonia, urinary tract infections, ileus, narcotic dependency etc. Indeed, the greater the trauma, the greater the response. MISS plays an important role in reduction of this surgical stress response and associated complications.7
  • 5. 310 Apollo Medicine 2012 December; Vol. 9, No. 4 Short term benefit like lower intraoperative blood loss, fewer infections, less intensive care utilization, less postoperative analgesia, and shorter hospitalization with MISS vis a vis traditional open surgeries are more as compared to long term benefits. MISS techniques may reduce postoperative wound infections as much as 10-fold compared with other large series of open spinal surgery published in the literature.15 The steep learning curve of MISS has been one of the greatest barriers to the widespread adoption of minimally invasive spine surgery. The surgeon practicing this needs a specialized training and experience. He should be expert in doing open surgeries too, as at times he may need to convert to open procedure, if it is not feasible to carry on with MISS. MISS has a disadvantage of being an instrumentation dependent procedure. MISS techniques require an extensive knowledge of the focal structural/radiological anatomy and safe surgical corridors of spinal region of interest.16 Additionally, one should be aware of possible anatomical variations and analyze them carefully in preoperative imaging to avoid operative complications. MISS requires significant practice and didactic training to acquire the skills necessary to perform it safely. MISS entails higher cost of treatment especially in instrumented cases where the cost of dedicated implants and instruments is more than once used in traditional surgeries. However this increase in cost can be offset by advantages of MISS like lesser hospital stay, lesser complications, lesser blood loss and earlier return to functional status which allows lesser postoperative expenditure and earlier resumption of productivity of patient.17 High radiation exposure to patient and operative team in MISS is a cause of concern being 10e20 times greater compared to traditional open methods.18 Instrumentation in MISS is blindfolded and entails frequent use of fluoroscopy at multiple stages. The steep learning course in MISS further makes the operating surgeon to use fluoroscope frequently to assure proper placement of implants.16 In traditional open procedures, many experienced spine surgeons place pedicle screws with freehand technique based on anatomical landmarks and hardly use intraoperative imaging to guide the open placement of pedicle screws, so a requirement for numerous intraoperative radiographs in MISS can be a considerable deterrent to the adoption of minimally invasive techniques. Although, it has been shown that with growing experience the amount of radiation tends to decrease but it still remains higher than traditional open approaches. Introduction of computer navigation and continuous electromyography (EMG) monitoring as an adjunct in MISS19 has potential to reduce the amount of radiation, but again the navigation systems are not widely available owing to high establishment cost and need of additional dedicated technical expertise. Jaiswal MISS is an exciting development in field of spine surgery and to some extent has stood its promise and scientifically ratified. However there is a need of high quality multicentre randomized control studies with large study population to clearly elucidate the advantages and disadvantages of MISS before it is accepted as a “Gold standard” in spinal surgeries. Moreover clinicians and researchers need to constantly endeavor to find out ways to simplify the procedure, reduce the financial implications, reduce the steep learning curve, improve clinical accuracy, reduce peroperative radiation and broaden the clinical applications of MISS. CONFLICTS OF INTEREST The author has none to declare. REFERENCES 1. Asgarzadie F, Khoo LT. Minimally invasive operative management for lumbar spinal stenosis: overview of early and long-term outcomes. Orthop Clin North Am. 2007 Jul;38(3):387e399. abstract vievii. Review. 2. Guiot BH, Khoo LT, Fessler RG. A minimally invasive technique for decompression of the lumbar spine. Spine (Phila Pa 1976). 2002 Feb 15;27(4):432e438. 3. Armin SS, Holly LT, Khoo LT. Minimally invasive decompression for lumbar stenosis and disc herniation. Neurosurg Focus. 2008;25(2):E11. Review. 4. Shunwu F, Xing Z, Fengdong Z, Xiangqian F. Minimally invasive transforaminal lumbar interbody fusion for the treatment of degenerative lumbar diseases. Spine (Phila Pa 1976). 2010 Aug 1;35(17):1615e1620. 5. Peng CW, Yue WM, Poh SY, Yeo W, Tan SB. Clinical and radiological outcomes of minimally invasive versus open transforaminal lumbar interbody fusion. Spine (Phila Pa 1976). 2009 Jun 1;34(13):1385e1389. 6. Dasenbrock HH, Juraschek SP, Schultz LR, et al. The efficacy of minimally invasive discectomy compared with open discectomy: a meta-analysis of prospective randomized controlled trials. J Neurosurg Spine. 2012 May;16(5):452e462. 7. Kim CW. Scientific basis of minimally invasive spine surgery: prevention of multifidus muscle injury during posterior lumbar surgery. Spine (Phila Pa 1976). 2010 Dec 15;35(26 suppl): S281eS286. Review. 8. Teli M, Lovi A, Brayda-Bruno M, et al. Higher risk of dural tears and recurrent herniation with lumbar micro-endoscopic discectomy. Eur Spine J. 2010 Mar;19(3):443e450. Epub 2010 Feb 3. 9. Schizas C, Kosmopoulos V. Percutaneous surgical treatment of chance fractures using cannulated pedicle screws. Report of two cases. J Neurosurg Spine. 2007 Jul;7(1):71e74.
  • 6. Minimally invasive spine surgeries (MISS) 10. Rampersaud YR, Annand N, Dekutoski MB. Use of minimally invasive surgical techniques in the management of thoracolumbar trauma: current concepts. Spine (Phila Pa 1976). 2006 May 15;31(11 suppl):S96eS102. discussion S104. Review. 11. Yeung AT, Tsou PM. Posterolateral endoscopic excision for lumbar disc herniation: surgical technique, outcome, and complications in 307 consecutive cases. Spine (Phila Pa 1976). 2002 Apr 1;27(7):722e731. 12. Hoogland T, Schubert M, Miklitz B, Ramirez A. Transforaminal posterolateral endoscopic discectomy with or without the combination of a low-dose chymopapain: a prospective randomized study in 280 consecutive cases. Spine (Phila Pa 1976). 2006 Nov 15;31(24):E890eE897. 13. Phillips FM. Minimally invasive treatments of osteoporotic vertebral compression fractures. Spine (Phila Pa 1976). 2003 Aug 1;28(15 suppl):S45eS53. Review. 14. McAfee PC, Phillips FM, Andersson G, et al. Minimally invasive spine surgery. Spine (Phila Pa 1976). 2010 Dec 15;35(26 suppl):S271eS273. Theme Symposium 311 15. O’Toole JE, Eichholz KM, Fessler RG. Surgical site infection rates after minimally invasive spinal surgery. J Neurosurg Spine. 2009 Oct;11(4):471e476. 16. Lee JC, Jang HD, Shin BJ. Learning curve and clinical outcomes of minimally invasive transforaminal lumbar interbody fusion: our experience in 86 consecutive cases. Spine (Phila Pa 1976). 2012 Aug 15;37(18):1548e1557. 17. Allen RT, Garfin SR. The economics of minimally invasive spine surgery: the value perspective. Spine (Phila Pa 1976). 2010 Dec 15;35(26 suppl):S375eS382. Review. 18. Mariscalco MW, Yamashita T, Steinmetz MP, Krishnaney AA, Lieberman IH, Mroz TE. Radiation exposure to the surgeon during open lumbar microdiscectomy and minimally invasive microdiscectomy: a prospective, controlled trial. Spine (Phila Pa 1976). 2011 Feb 1;36(3):255e260. 19. Wood MJ, Mannion RJ. Improving accuracy and reducing radiation exposure in minimally invasive lumbar interbody fusion. J Neurosurg Spine. 2010 May;12(5):533e539.
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