SPINE Volume 30, Number 16S, pp S52–S59 ©2005, Lippincott Williams & Wilkins, Inc. Minimal Access Surgical Techniques in the Management of the Painful Lumbar Motion Segment John W. German, MD, and Kevin T. Foley, MD Study Design. Review article. Objectives. To provide an overview of current mini- mally invasive lumbar fusion techniques. Summary of Background Data. Minimally invasive lumbar fusion techniques have only recently been devel- oped. The goals of these procedures are to reduce ap- proach-related soft tissue injury while allowing the sur- gery to be conducted in an effective manner. Methods. Pertinent literature and the authors’ clinical experience are reviewed. Results. Minimally invasive techniques have been de- veloped for intertransverse process, posterior lumbar in- terbody, and transforaminal lumbar interbody fusions. The indications, advantages, and disadvantages of each technique are described. It is emphasized that while they appear promising, the clinical results of these techniques remain preliminary with few long-term studies available for critical review. Conclusions. Preliminary clinical evidence suggests that minimally invasive lumbar fusion techniques will benefit patients with spinal disorders. Key words: lumbar fusion, minimally invasive surgery, pedicle screw, percutaneous. Spine 2005;30:S52–S59 Good long-term outcomes after conventional lumbar fu- sion may be limited by inappropriate patient selection, 1,2 instrumentation misplacement, 3,4 graft site harvest, 5,6 pseudarthrosis, 5,6 juxtafusional degeneration, 7,8 and ex- tensive approach-related soft tissue disruption. 9 –16 At the current time, the issues of patient selection and in- strumentation misplacement remain heavily dependent on the surgeon’s decision-making and technical compe- tencies. The introduction of the bone graft substitute, human recombinant bone morphogenetic protein-2 (rhBMP-2), into clinical practice has helped address the issues of graft site morbidity and pseudarthrosis. 5,6 Lum- bar arthroplasty is currently being investigated in two randomized, prospective trials as a means to limit juxta- fusional degeneration. 17–20 Given the poor preliminary results of total disc arthroplasty in the face of concurrent facet degeneration, this approach is likely to be limited in its application to chronic low back pain. 21,22 Thus, for the immediate future, lumbar fusion will remain the sur- gical treatment of choice for many patients with painful lumbar motion segments. The main impetus for the development of minimal access spinal procedures was to limit the approach- related soft tissue dissection. It was thought that this dissection resulted in increased postoperative pain, im- paired spinal function, lengthened recovery time, and increased disability. Although still novel, the main prom- ise of such techniques is decreased soft tissue injury with an improvement of patient outcomes. This article reviews the rationale for minimal access spine surgery, provides a technical overview of the pro- cedures, and describes early clinical results of such ap- proaches from the literature and our institution. It should be emphasized that minimal access lumbar fusion techniques are in their infancy with preliminary results at best. Ultimately, the clinical utility of these approaches will be dictated by their long-term results. Rationale for Minimal Access Spinal Surgery The rationale for the development of minimal access spi- nal procedures includes the ability to reduce approach- related morbidity while meeting the same goals of the traditional open procedure. Each of these key concepts will be addressed separately. Minimize Approach-Related Morbidity Minimally invasive procedures have become a standard for the management of a multitude of pathologic condi- tions in various surgical disciplines. Laparoscopic chole- cystectomy remains a quintessential example of this ap- proach in general surgery. This technique has now essentially replaced open cholecystectomy because of the relative ability to limit morbidity, limit postoperative in- patient admissions, decrease cost, and improve long- term outcomes. 23,24 Currently, there is almost no surgi- cal discipline in which a minimally invasive approach to a standard open procedure has not been entertained. Open instrumented lumbar fusion procedures require lengthy hospital admissions and are costly. 25–27 As noted above, the long-term morbidity associated with these procedures is concerning. A significant proportion of this morbidity is iatrogenic and likely due to the extensive soft tissue and muscle dissection required to obtained adequate exposure of the spine for fusion. Several inves- tigators have documented the harmful effects of this dis- section in laboratory animals and humans using a variety of investigational techniques (Table 1). 9 –16,28 –35 The From the Department of Neurosurgery, University of Tennessee, Mem- phis and Semmes-Murphey Clinic, Memphis, TN. Acknowledgment date: November 8, 2004. Acceptance date: May 24, 2005. The device(s)/drug(s) is/are FDA-approved or approved by correspond- ing national agency for this indication, except for the use of rhBMP in posterolateral or posterior interbody fusion, which is an off- label use. No funds were received in support of this work. One or more of the authors has/have received or will receive benefits for personal or pro- fessional use from a commercial party related directly or indirectly to the subject of this manuscript: royalties, stocks, stock options, decision making position. Address correspondence and reprint requests to Kevin T. Foley, MD, Semmes-Murphey Clinic, 1211 Union Avenue, Suite 200, Memphis, TN 38104; E-mail: kfoley@usit.net S52