Extract
The last decade has seen an evolution of minimally invasive spine surgery with new technological developments. Minimally invasive spine surgery is thought to decrease postoperative pain and allow quicker recovery by limiting soft-tissue retraction and dissection. Advances in microscopy, tissue retractors, and specialized instruments have enabled surgeons to perform procedures through small incisions. As with the open approach, the goals of the minimally invasive approach are to adequately decompress the involved neural elements, stabilize the motion segment, and/or realign the spinal column according to the needs of the individual patient. This article is an overview of the current state of minimally invasive spine surgery and a discussion of the key biologic concepts of posterior lumbar decompression as well as posterior and lateral fusion techniques.
The last decade has seen an evolution of minimally invasive spine surgery with new technological developments. Minimally invasive spine surgery is thought to decrease postoperative pain and allow quicker recovery by limiting soft-tissue retraction and dissection. Advances in microscopy, tissue retractors, and specialized instruments have enabled surgeons to perform procedures through small incisions. As with the open approach, the goals of the minimally invasive approach are to adequately decompress the involved neural elements, stabilize the motion segment, and/or realign the spinal column according to the needs of the individual patient. This article is an overview of the current state of minimally invasive spine surgery and a discussion of the key biologic concepts of posterior lumbar decompression as well as posterior and lateral fusion techniques.
Minimally invasive posterior lumbar surgery is based on the following key concepts: (1) avoid muscle crush injury by self-retaining retractors, (2) do not disrupt tendon attachment sites of key muscles, particularly the origin of the multifidus muscle at the spinous process, (3) utilize known anatomic neurovascular and muscle compartment planes, and (4) minimize collateral soft-tissue injury by limiting the width of the surgical corridor.
One of the main goals of minimally invasive spine surgery is to reduce trauma to the two posterior paraspinal muscle groups—(1) the deep paramedian transversospinalis muscle group, including the multifidus, interspinales, intertransversarii, and short rotators, and (2) the more superficial and lateral erector spinae muscles including the longissimus and iliocostalis (Fig. 1). These muscles run along the thoracolumbar spine and attach caudally. The multifidus muscle in particular is important for dynamic stability of the spine (see Appendix).
The traditional midline posterior approach for lumbar decompression and fusion traumatizes some paraspinous tissue. The tendon origin of the multifidus muscle is detached, the surgical site is wide, and muscle crush injury may occur with the use of self-retaining retractors, all of which may result in muscle atrophy1-9. Atrophy, in turn, leads to decreased force-production capacity of the muscle10,11. Kim et al. compared trunk muscle strength between patients treated with open posterior spinal instrumentation and those managed with percutaneous instrumentation12. Patients who had undergone percutaneous instrumentation had >50% improvement in lumbar extension strength, whereas those treated with open surgery had no improvement.
Muscle biopsy specimens from patients undergoing revision spine surgery have revealed selective type-II fiber atrophy, widespread fiber-type grouping (a sign of reinnervation), and a "moth-eaten" appearance of muscle fibers13. While there may be several causes, the most important factor responsible for muscle injury is the use of forceful self-retaining retractors. Kawaguchi et al. proposed that injury is induced by a crush mechanism similar to that caused by a pneumatic tourniquet during surgery on the extremities6,14-17. During the application of self-retaining retractors, elevated pressures lead to decreased intramuscular perfusion18,19. The severity of the muscle injury is affected by the degree of the intramuscular pressure and the length of the retraction time. Using MRI (magnetic resonance imaging), Stevens et al. assessed the postsurgical appearance of the multifidus muscle20. Patients treated with a traditional open posterior transforaminal lumbar interbody fusion technique showed marked intramuscular edema on postoperative MRI six months after the surgery, while patients treated with a mini-open transforaminal lumbar interbody fusion had nearly normal findings on MRI. Tsutsumimoto et al. used MRI to assess the multifidus muscle in patients treated with a posterior lumbar interbody fusion21. They compared two groups of patients: those who had had a traditional midline approach and those who had had a mini-open Wiltse approach. The degree of multifidus atrophy and the increase in T2-signal intensity in the multifidus muscle after the mini-open posterior lumbar interbody fusion were significantly lower than those following open posterior lumbar interbody fusion.
Another mechanism leading to degeneration and atrophy following traditional open surgery is muscle denervation. The nerve supply to the multifidus is monosegmental, making it especially vulnerable to injury22,23. Damage to the neuromuscular junction following prolonged retraction can also lead to muscle denervation. Muscle biopsies in patients with failed back surgery syndrome showed signs of advanced chronic denervation24.
Soft-tissue trauma can have widespread regional and systemic effects. Kim et al. compared levels of circulating markers of tissue injury in patients who had undergone open spinal fusion with those in patients treated with minimally invasive spine surgery25. The levels of creatinine kinase, aldolase, pro-inflammatory cytokines (IL-6 [interleukin-6] and IL-8), and anti-inflammatory cytokines (IL-10 and IL-1 receptor antagonist) in the patients treated with the open surgery were altered several-fold compared with those in the patients treated with the minimally invasive surgery. Most markers returned to baseline levels by three days after the minimally invasive surgery, whereas they required seven days to return to baselines levels after the open surgery. Glycerol is an important component of glycerophospholipid, the basic structure of the cell plasma membrane. When the integrity of a cell membrane is destroyed, glycerol is released into the interstitial fluid. Ren et al. demonstrated that the glycerol concentrations in the paraspinal muscles of patients who had undergone posterolateral lumbar fusion with instrumentation were higher than the concentrations in the deltoid muscles of the same patients26.
Another goal of minimally invasive spine surgery is to limit the amount of osseous resection to minimize postoperative spinal instability27,28. The disruption of facet joint integrity combined with loss of the midline interspinous ligament-tendon complex associated with traditional laminectomy can contribute to flexion instability29-31. Efforts to limit such potentially destabilizing surgery have been pursued via unilateral laminotomies in which the spinous processes and corresponding tendinous attachments of the multifidus muscle and the supraspinous and interspinous ligaments are preserved. A finite element analysis demonstrated that minimizing bone and ligament removal resulted in greater preservation of normal motion of the lumbar spine after surgery32.
Minimally Invasive Tubular Microdiscectomy
The treatment of herniated discs via minimally invasive tubular microdiscectomy is the most common minimally invasive spine technique currently used in the United States. This system, developed by Foley and Smith, consists of a series of concentric dilators and thin-walled tubular retractors of variable length33-35. The tube, typically 18 mm in diameter, circumferentially defines a surgical corridor. Surgery is typically performed with use of an operating microscope. Several recent studies have compared minimally invasive lumbar discectomy with the traditional open approach and have demonstrated that the minimally invasive approach resulted in less intraoperative tissue damage, nerve irritation, blood loss, and immediate postoperative pain as well as a shorter period of hospitalization and a faster recovery and return to work36-40. Randomized controlled trials comparing traditional open microdiscectomy with minimally invasive tubular microdiscectomy41-43 all showed that tubular microdiscectomy is safe and efficacious.
The surgical corridor is defined by the specific pathological entity. Minimally invasive lumbar decompression can adequately decompress the central, lateral, and foraminal zones of the spinal canal and can be used to remove disc material from the extraforaminal region. However, the access strategy for decompression of each region of the spine should be planned preoperatively. Extraforaminal neural compression may be approached from outside of the spinal canal by inserting the tubular retractor over the intertransverse membrane between the transverse processes. The intertransverse membrane is identified and released to expose the exiting nerve root. Once the root is identified, the disc material in the extraforaminal zone can be accessed deep to the nerve root.
Minimally Invasive Lumbar Hemilaminectomy
The key principle in minimally invasive spine decompression is maintenance of the multifidus tendon attachment to the spinous process. During a traditional laminectomy, the spinous process is removed and the multifidus muscle is retracted laterally. On wound closure, the multifidus origin cannot be repaired to the spinous process. However, a thorough decompression can be achieved through a unilateral portal via a hemilaminectomy technique44. The central canal and the contralateral recess can be decompressed by angling the tubular retractor dorsally to view the undersurface of the spinous process and the contralateral lamina (Fig. 2). The dural tube can be gently pushed down, and the ligamentum flavum and the contralateral superior articular process are resected to achieve a bilateral decompression. The upper lumbar spine anatomy differs from the lower lumbar spine anatomy. At L3 and above, the lamina between the spinous process and the facet joint can be narrow (Fig. 2). With a unilateral approach, it may be difficult to reach the ipsilateral recess without removing an excessive amount of the ipsilateral inferior articular process. An option is to utilize a bilateral cross-over technique to reach the right lateral recess from a left-sided hemilaminectomy and vice versa. In a small preliminary study of four patients and seven levels of decompression performed with this technique, the total operating time averaged thirty-two minutes per level and the estimated blood loss averaged 75 mL. The average postoperative stay was 1.2 days. All patients had resolution of neurogenic claudication, and there were no complications45.
The efficacy and safety of minimally invasive posterior lumbar decompression have been assessed44,46-55. The learning curve for minimally invasive spine surgery is a concern, as the patients who had been treated during the initial phases of some studies had higher complication rates53,55. In a study of their experience with a minimally invasive unilateral approach to bilateral lumbar decompression for treatment of lumbar stenosis, Ikuta et al. reported good short-term results in thirty-eight of forty-four patients53. The mean improvement in the Japanese Orthopaedic Association score was 72%. Postoperative morbidity was relatively low and, compared with a control group treated with open surgery, the patients had decreased intraoperative blood loss, decreased pain medication requirements, and shorter hospital stays. The authors reported a 25% complication rate, including four dural tears, three fractures of the inferior facet on the approach side, one postoperative cauda equina syndrome requiring a reoperation, and one postoperative epidural hematoma requiring a reoperation.
In a prospective study, Yagi et al. randomly assigned forty-one patients with lumbar stenosis to undergo either a minimally invasive microendoscopic decompression (twenty patients) or a conventional laminectomy (twenty-one patients)56. The duration of follow-up averaged eighteen months. The patients treated with the minimally invasive decompression had a shorter mean hospital stay, less blood loss, a lower mean creatine phosphokinase muscle isoenzyme level, a lower visual analog scale score for back pain at one year postoperatively, and a faster recovery rate. Satisfactory neurological decompression and symptom relief were achieved in 90% of the patients, and no patient had spinal instability. Castro-Menéndez et al. treated fifty patients with lumbar spinal stenosis with a microendoscopic decompression using an 18-mm tubular retractor57. The authors reported good or excellent results in 72% of the patients, with 68% expressing good subjective satisfaction, at a mean of four years. The mean decrease in the Oswestry Disability Index was 30.23, and the mean decrease in the visual analog scale score for leg pain was 6.02.
Asgarzadie and Khoo reported on forty-eight patients who had undergone minimally invasive lumbar decompression for lumbar stenosis58. Twenty-eight patients underwent a one-level decompression, and twenty patients underwent a two-level decompression. Compared with a control group treated with a traditional open laminectomy, the group with minimally invasive surgery had, on average, less intraoperative blood loss (25 versus 193 mL) and a shorter hospital stay (thirty-six versus ninety-four hours). Four-year clinical outcomes were available for thirty-two of the forty-eight patients. All patients reported improvement in walking endurance at six months following surgery, and 80% of the patients had maintained improvement in walking endurance at a mean of thirty-eight months. Improvements in both the Oswestry Disability Index and the Short Form-36 (SF-36) score had been sustained during the follow-up period. There were no neurological complications.
The use of minimally invasive techniques for spine surgery may be advantageous in patients who are elderly, medically frail, or obese40,59-61. In a retrospective case study, Tomasino et al. compared operative results and patient outcomes between obese and nonobese patients who had undergone a one-level lumbar microdiscectomy or a laminectomy with use of tubular retractors62. Of 115 patients, 31% were obese. No significant differences were seen between obese and nonobese patients in terms of incision length, operative time, blood loss, or complications.
Minimally invasive decompression without fusion may be efficacious in patients with degenerative spondylolisthesis. Pao et al. performed a microdecompression on thirteen patients with stenosis from a grade-I spondylolisthesis63. There was no progression of vertebral slippage, and all patients reported a good outcome. Sasai et al. performed a unilateral approach with bilateral decompression in twenty-three patients with degenerative spondylolisthesis and twenty-five patients with degenerative spinal stenosis64. At two years, the Neurogenic Claudication Outcome Scores and Oswestry Disability Indices were similar between the two groups, although the patients with spondylolisthesis had a somewhat worse outcome. A progression of vertebral slippage of =5% was found in three of the twenty-three patients with degenerative spondylolisthesis. Kleeman et al. performed a spinous process and interspinous ligament-preserving decompression to treat spinal stenosis in fifteen patients who had an average degenerative spondylolisthesis of 6.7 mm65. After an average of four years of follow-up, two patients had an increase in the slip, with associated worsening of their symptoms, while twelve reported good to excellent results.
Transforaminal lumbar interbody fusion, originally described by Blume and Rojas and later popularized by Harms and Jeszensky, is an adaptation of the posterior lumbar interbody fusion technique first described by Cloward66-68. In contrast to posterior lumbar interbody fusion, which requires a wide decompression and bilateral nerve-root retraction to access the disc space, transforaminal lumbar interbody fusion is done via a unilateral approach to the disc space through the intervertebral foramen (Fig. 3). Compared with bilateral posterior lumbar interbody fusion, transforaminal lumbar interbody fusion requires less neural retraction69-71. One of its main advantages is that the approach allows pathological conditions such as spinal stenosis to be treated concurrently with an anterior interbody fusion through a single posterior incision (Fig. 4).
Peng et al. compared the clinical and radiographic outcomes of minimally invasive transforaminal lumbar interbody fusion with those of traditional open transforaminal lumbar interbody fusion72. At two years, the outcomes were similar, but the patients who had had the minimally invasive surgery had the additional benefits of less initial postoperative pain, early rehabilitation, shorter hospitalization, and fewer complications. Dhall et al. retrospectively compared the outcomes of twenty-one patients who had undergone a mini-open transforaminal lumbar interbody fusion with those of twenty-one patients treated with a traditional open transforaminal lumbar interbody fusion and reported that there was significantly more blood loss and a longer hospital stay after the open transforaminal lumbar interbody fusion, although there was no difference in the clinical outcomes at two years73. Selznick et al. reported that minimally invasive transforaminal lumbar interbody fusion is technically feasible in revision cases and is not associated with more blood loss or neurological morbidity than are found with primary procedures74. However, there was a higher rate of incidental durotomy. Minimally invasive transforaminal lumbar interbody fusions in the revision setting are challenging procedures and should be performed by surgeons with experience using minimally invasive techniques.
In a prospective study, Kasis et al. found that limited-exposure posterior lumbar interbody fusion provided better clinical outcomes and shorter hospital stays when compared with a traditional open approach75. The authors noted that (1) preservation of posterior elements, (2) avoidance of far lateral dissection over the transverse processes, (3) a bilateral total facetectomy, (4) fewer neurological complications, and (5) an avoidance of iliac crest autograft were all responsible for the improved outcomes.
Interbody lumbar fusion is a popular technique with touted benefits that include eliminating the disc as a potential pain generator, high rates of fusion, and restoration of intervertebral disc height and lumbar lordosis76-78. These benefits can be achieved with anterior lumbar interbody fusion, posterior or transforaminal lumbar interbody fusion, or an endoscopic lateral retroperitoneal approach79. A minimally invasive retroperitoneal direct lateral transpsoas approach to interbody arthrodesis has been described80,81. This technique involves a minimally invasive approach through the retroperitoneal space and the psoas muscle, with reliance on neural monitoring and fluoroscopy to provide the ability to achieve an interbody fusion (Figs. 5 and 6).
The iliac wing blocks minimally invasive lateral exposure below L4-L5 (Fig. 5). Limiting the dissection to the anterior third to anterior half of the psoas muscle reduces the risk of neural injury because the lumbar plexus is in the posterior half of the psoas muscle80,82,83. The use of intraoperative electromyographic (EMG) monitoring helps reduce the risk of neural injury (Fig. 6)84. While preparing the disc space for interbody fusion and inserting the interbody device, one should not violate the end plates and should confirm the orientation with both anteroposterior and lateral imaging (Fig. 7). Indirect foraminal decompression is possible by restoring the neuroforaminal height and sagittal alignment during the interbody fusion. The decision whether to include a posterior spinal fusion or decompression is individualized (Fig. 8).
Knight et al. reported the early complications in forty-three female and fifteen male patients who had undergone minimally invasive direct lateral interbody fusion85: six patients had postoperative meralgia paresthetica, and two had L4 nerve-root injuries.
Ozgur et al. reported on thirteen patients treated with a single or multilevel extreme lateral interbody fusion80. The patients had significant relief of pain and improvement in functional scores without any complications. Anand et al. reported on twelve patients treated with direct lateral interbody fusion in combination with a transsacral interbody fusion technique at L5-S186. The patients had an average of 3.6 levels fused, and the correction of the Cobb angle was from an average of 18.9° preoperatively to an average of 6.2° postoperatively86. Pimenta et al. reported on thirty-nine patients treated with direct lateral interbody fusion at an average of 2.0 levels. Scoliosis improved from an average of 18° preoperatively to an average of 8° postoperatively and lumbar lordosis increased from an average of 34° preoperatively to an average of 41° postoperatively81. All patients were walking and tolerating a regular diet on the day of the surgery. The average blood loss was <100 mL, and the average operative time was 200 minutes. The average duration of hospitalization was 2.2 days. Pain scores and functional scores improved. In a larger series, Wright reported the results of extreme lateral interbody fusion in 145 patients treated for degenerative disc disease at multiple institutions87. The number of levels treated ranged from one to four (72% of the procedures were at a single level; 22%, at two levels; 5%, at three levels; and 1%, at four levels). Interbody spacers (polyetheretherketone [PEEK] in 86%, allograft in 8%, and a cage in 6%) were used in conjunction with bone morphogenetic protein (52%), demineralized bone matrix (39%), or autograft (9%). Twenty percent of the operations were stand-alone interbody fusions, 23% used a lateral rod-screw construct, and 58% used posterior pedicle screws. The average operative time was seventy-four minutes, and the average blood loss was 88 mL. There were two transient genitofemoral injuries, and five patients experienced transient hip flexor weakness. Most patients walked on the day of surgery and were discharged on the first postoperative day.
Akbarnia et al. reported on thirteen patients who had had multilevel extreme lateral interbody fusion for the treatment of adult lumbar scoliosis of >30°88. A mean of three levels were treated, and all procedures were combined with posterior spinal fusion and instrumentation. Substantial improvements in lumbar scoliosis and lordosis were found at a mean of nine months. One graft required revision because of migration, and one hernia occurred at the level of the incision for the extreme lateral interbody fusion. All cases of psoas muscle weakness or thigh numbness or pain resolved within six months. Short-term postoperative visual analog scale, Scoliosis Research Society-22, and Oswestry Disability Index scores were improved compared with preoperative scores. Similar results were shown by Anand et al., in a series of twelve patients86. The number of levels treated ranged from two to eight (mean, 3.64). The mean blood loss was 163.89 mL (SD [standard deviation], 105.41 mL) for anterior procedures and 93.33 mL (SD, 101.43 mL) for posterior percutaneous pedicle screw fixation. The mean surgical time was 4.01 hours (SD, 1.88 hours) for anterior procedures and 3.99 hours (SD, 1.19 hours) for posterior procedures. The mean Cobb angle improved significantly from 18.93° (SD, 10.48°) preoperatively to 6.19° (SD, 7.20°) at a mean of seventy-five days postoperatively.
The rationale for minimally invasive pedicle screw insertion into the spine, which can be performed percutaneously or via a paramedian mini-open technique, is to preserve multifidus muscle function. With the percutaneous technique, the pedicle is entered with use of a Jamshidi-type trocar needle under fluoroscopic control (see Appendix). Once the needles are within the pedicles, the stylets are removed and guidewires inserted. Sequential soft-tissue dilators are used to create a path for the tap and screw. The outermost dilator can be used as a protective sleeve during pedicle tapping. The guidewire is then used to direct cannulated taps and screws into the pedicle. A cannulated pedicle screw is placed over the guidewire. Rods are inserted percutaneously to minimize soft-tissue trauma (Fig. 9).
With the mini-open technique, a longitudinal, paramedian incision is placed slightly lateral to the lateral edge of the pedicles. Dissection is performed through the intermuscular plane between the multifidus and longissimus muscles. A tubular retractor system is subsequently deployed after tissue dilation is performed. The pars interarticularis and the mammillary processes of the cephalad and caudad levels are exposed. A high-speed burr is utilized to create a starting point, and pedicle probes are used to enter the pedicle. Cannulated or non-cannulated pedicle screws can be used with this technique. The exposure allows for decortication of the pars, facet joint, and transverse processes for bone-grafting and fusion.
The mini-open technique offers several advantages over the percutaneous method. It allows direct visualization of the anatomy and the choice of using either cannulated or non-cannulated pedicle-screw systems. The mini-open technique also allows greater access for bone-grafting posteriorly. However, the mini-open technique threatens the medial branch of the dorsal rami, which extends downward to the transverse process of the caudad level. The nerve then curves posteriorly, where it branches to supply the multifidus muscle, the intertransverse muscles and ligaments, and the facet joint of the cephalad level. As a result, insertion of a pedicle screw through the mammillary process at one level can cause injury to the medial branch of the dorsal rami that supplies the adjacent cephalad level. In a cadaveric study comparing these minimally invasive spine techniques, Regev et al. found that the mini-open technique causes injury to the medial branch of the dorsal rami more frequently than does the percutaneous technique89. They recommended that pedicle screw insertion at the cephalad level be performed percutaneously if one desires to minimize denervation of the multifidus complex at the cephalad adjacent level.
Overall safety and accuracy have been reported for minimally invasive pedicle screw insertion. Ringel et al. assessed 488 pedicle screws implanted in a total of 103 patients via a percutaneous technique90. They found that only 3% of the screws were rated as unacceptable, leading to nine screw-revision surgical procedures. These results mirror a growing body of evidence that reflect the safety and efficacy of minimally invasive posterior spinal instrumentation91-93. In a meta-analysis of 130 studies and 37, 337 pedicle screws placed, the overall screw-placement accuracy was 91.3%94.
Radiation Exposure
There are several techniques for minimally invasive posterior screw insertion, but the percutaneous pedicle screw technique is the least tissue-disruptive and has been adapted by some for single or multilevel fusions. Its use, however, depends on intraoperative multiplanar fluoroscopy. The operative time for insertion of two screws at the same vertebral level reaches ten minutes or longer with the use of advanced fluoroscopic techniques, whereas lateral-only fluoroscopic methods require less than five minutes per level95-97. With increased insertion times associated with advanced fluoroscopic guidance, the cumulative exposure to radiation increases concomitantly.
Studies have shown that fluoroscopically guided pedicle screw placement exposes surgeons to a dose of radiation that is ten to twelve times the dose associated with non-spinal musculoskeletal procedures98. Despite these concerns, the convenience of the c-arm, combined with a high degree of accuracy, has made intraoperative fluoroscopy an increasingly necessary part of advanced minimally invasive spine surgery. Exposure of both the surgeon and the patient to radiation was analyzed in a prospective study of twenty-four consecutive patients who underwent minimally invasive transforaminal lumbar interbody fusion99. The mean fluoroscopy time was 1.69 minutes (range, 0.82 to 3.73 minutes) per case. The authors concluded that patient exposures were low and compared favorably with those associated with other common interventional fluoroscopically guided procedures. Kim et al. showed that the use of navigation-assisted fluoroscopy for minimally invasive transforaminal lumbar interbody fusion markedly decreases direct exposure to radiation by allowing the surgeon to step away from the surgical field during image acquisition100. In addition to reducing radiation exposure, navigation eliminates the need for cumbersome protective lead gear and eliminates the need for fluoroscopy during surgery.
Learning Curve for Minimally Invasive Spine Surgery
The barriers to widespread adoption of minimally invasive techniques appear to be related to technical difficulties of the procedures and a lack of adequate training opportunities. Webb et al. showed that most spinal surgeons perceive minimally invasive spine surgery to be efficacious and most wish to perform more of the procedures101. However, most surgeons have not pursued minimally invasive spine surgery because of concerns about technical difficulties of the procedure and a lack of adequate training opportunities. Nowitzke evaluated the learning curve for tubular decompression and noted that three of the first seven cases performed in their series, but none of the subsequent twenty-eight, required conversion to open surgery102. Villavicencio et al. noted a higher rate of overall perioperative complications, Dhall et al. found a higher rate of instrumentation-related complications, and Peng et al. reported longer operative times when comparing minimally invasive transforaminal lumbar interbody fusion with open transforaminal lumbar interbody fusion72,73,103. Improving the learning curve for minimally invasive spine surgery requires studies to better the understanding of the specific portions of the procedure that are most challenging and to thus allow for development of appropriate instrumentation and improved training techniques.
The posterior spine is dynamically stabilized by a diverse group of muscles that lie in close proximity to the vertebrae and possess multiple tendon insertion sites. In humans, stability and motion are controlled by active and passive means. The multifidus muscle is a powerful spine stabilizer as it has short and powerful fibers that enable it to produce large forces over short distances. Traditional posterior midline open approaches disrupt the function of this muscle through tendon detachment, devascularization, and crush injury. Minimally invasive spine surgery techniques were developed in an attempt to minimize surgical damage and preserve normal function. The rationale of this approach relies on limiting the surgical corridor to the minimum necessary to safely expose the surgical target site and to minimize injury to the anatomic structures necessary for normal function. The traditional use of self-retaining retractors, which can induce crush injuries to muscle, has been supplanted by table-mounted, tubular-type retractors that minimize pressure on muscles, vessels, and nerves. As minimally invasive spine surgery continues to evolve, it is important to properly evaluate the risks and benefits of various minimally invasive techniques with prospective, long-term clinical studies.
Figures showing muscle microarchitectural design and methods of percutaneous pedicle screw insertion are available with the electronic version of this article on our web site at jbjs.org (go to the article citation and click on "Supporting Data").
Datta
G;
Gnanalingham
KK;
Peterson
D;
Mendoza
N;
O'Neill
K;
Van Dellen
J;
McGregor
A;
Hughes
SP. Back pain and disability after lumbar laminectomy: is there a relationship to muscle retraction?Neurosurgery.
2004;54:1413-20.[PubMed][CrossRef]
Gejo
R;
Kawaguchi
Y;
Kondoh
T;
Tabuchi
E;
Matsui
H;
Torii
K;
Ono
T;
Kimura
T. Magnetic resonance imaging and histologic evidence of postoperative back muscle injury in rats. Spine (Phila Pa 1976).
2000;25:941-6.[PubMed][CrossRef]
Gejo
R;
Matsui
H;
Kawaguchi
Y;
Ishihara
H;
Tsuji
H. Serial changes in trunk muscle performance after posterior lumbar surgery. Spine (Phila Pa 1976).
1999;24:1023-8.[PubMed][CrossRef]
Gille
O;
Jolivet
E;
Dousset
V;
Degrise
C;
Obeid
I;
Vital
JM;
Skalli
W. Erector spinae muscle changes on magnetic resonance imaging following lumbar surgery through a posterior approach. Spine (Phila Pa 1976).
2007;32:1236-41.[PubMed][CrossRef]
Hyun
SJ;
Kim
YB;
Kim
YS;
Park
SW;
Nam
TK;
Hong
HJ;
Kwon
JT. Postoperative changes in paraspinal muscle volume: comparison between paramedian interfascial and midline approaches for lumbar fusion. J Korean Med Sci.
2007;22:646-51.[PubMed][CrossRef]
Kawaguchi
Y;
Matsui
H;
Gejo
R;
Tsuji
H. Preventive measures of back muscle injury after posterior lumbar spine surgery in rats. Spine (Phila Pa 1976).
1998;23:2282-8.[PubMed][CrossRef]
Mayer
TG;
Vanharanta
H;
Gatchel
RJ;
Mooney
V;
Barnes
D;
Judge
L;
Smith
S;
Terry
A. Comparison of CT scan muscle measurements and isokinetic trunk strength in postoperative patients. Spine (Phila Pa 1976).
1989;14:33-6.[PubMed][CrossRef]
Motosuneya
T;
Asazuma
T;
Tsuji
T;
Watanabe
H;
Nakayama
Y;
Nemoto
K. Postoperative change of the cross-sectional area of back musculature after 5 surgical procedures as assessed by magnetic resonance imaging. J Spinal Disord Tech.
2006;19:318-22.[PubMed][CrossRef]
Rantanen
J;
Hurme
M;
Falck
B;
Alaranta
H;
Nykvist
F;
Lehto
M;
Einola
S;
Kalimo
H. The lumbar multifidus muscle five years after surgery for a lumbar intervertebral disc herniation. Spine (Phila Pa 1976).
1993;18:568-74.[PubMed][CrossRef]
Granata
KP;
Marras
WS. An EMG-assisted model of loads on the lumbar spine during asymmetric trunk extensions. J Biomech.
1993;26:1429-38.[PubMed][CrossRef]
Marras
WS;
Davis
KG;
Granata
KP. Trunk muscle activities during asymmetric twisting motions. J Electromyogr Kinesiol.
1998;8:247-56.[PubMed][CrossRef]
Kim
DY;
Lee
SH;
Chung
SK;
Lee
HY. Comparison of multifidus muscle atrophy and trunk extension muscle strength: percutaneous versus open pedicle screw fixation. Spine (Phila Pa 1976).
2005;30:123-9.[PubMed][CrossRef]
Mattila
M;
Hurme
M;
Alaranta
H;
Paljärvi
L;
Kalimo
H;
Falck
B;
Lehto
M;
Einola
S;
Järvinen
M. The multifidus muscle in patients with lumbar disc herniation. A histochemical and morphometric analysis of intraoperative biopsies. Spine (Phila Pa 1976).
1986;11:732-8.[PubMed][CrossRef]
Kawaguchi
Y;
Matsui
H;
Tsuji
H. Back muscle injury after posterior lumbar spine surgery. Part 2: histologic and histochemical analyses in humans. Spine (Phila Pa 1976).
1994;19:2598-602.[PubMed][CrossRef]
Kawaguchi
Y;
Matsui
H;
Tsuji
H. Back muscle injury after posterior lumbar spine surgery. Part 1: histologic and histochemical analyses in rats. Spine (Phila Pa 1976).
1994;19:2590-7.[PubMed][CrossRef]
Kawaguchi
Y;
Matsui
H;
Tsuji
H. Back muscle injury after posterior lumbar spine surgery. A histologic and enzymatic analysis. Spine (Phila Pa 1976).
1996;21:941-4.[PubMed][CrossRef]
Kawaguchi
Y;
Yabuki
S;
Styf
J;
Olmarker
K;
Rydevik
B;
Matsui
H;
Tsuji
H. Back muscle injury after posterior lumbar spine surgery. Topographic evaluation of intramuscular pressure and blood flow in the porcine back muscle during surgery. Spine (Phila Pa 1976).
1996;21:2683-8.[PubMed][CrossRef]
Taylor
H;
McGregor
AH;
Medhi-Zadeh
S;
Richards
S;
Kahn
N;
Zadeh
JA;
Hughes
SP. The impact of self-retaining retractors on the paraspinal muscles during posterior spinal surgery. Spine (Phila Pa 1976).
2002;27:2758-62.[PubMed][CrossRef]
Styf
JR;
Willén
J. The effects of external compression by three different retractors on pressure in the erector spine muscles during and after posterior lumbar spine surgery in humans. Spine (Phila Pa 1976).
1998;23:354-8.[PubMed][CrossRef]
Stevens
KJ;
Spenciner
DB;
Griffiths
KL;
Kim
KD;
Zwienenberg-Lee
M;
Alamin
T;
Bammer
R. Comparison of minimally invasive and conventional open posterolateral lumbar fusion using magnetic resonance imaging and retraction pressure studies. J Spinal Disord Tech.
2006;19:77-86.[PubMed][CrossRef]
Tsutsumimoto
T;
Shimogata
M;
Ohta
H;
Misawa
H. Mini-open versus conventional open posterior lumbar interbody fusion for the treatment of lumbar degenerative spondylolisthesis: comparison of paraspinal muscle damage and slip reduction. Spine (Phila Pa 1976).
2009;34:1923-8.[PubMed][CrossRef]
Macintosh
JE;
Bogduk
N. The morphology of the lumbar erector spinae. Spine (Phila Pa 1976).
1987;12:658-68.[PubMed][CrossRef]
Macintosh
JE;
Bogduk
N. The attachments of the lumbar erector spinae. Spine (Phila Pa 1976).
1991;16:783-92.[PubMed][CrossRef]
Sihvonen
T;
Herno
A;
Paljärvi
L;
Airaksinen
O;
Partanen
J;
Tapaninaho
A. Local denervation atrophy of paraspinal muscles in postoperative failed back syndrome. Spine (Phila Pa 1976).
1993;18:575-81.[PubMed][CrossRef]
Kim
KT;
Lee
SH;
Suk
KS;
Bae
SC. The quantitative analysis of tissue injury markers after mini-open lumbar fusion. Spine (Phila Pa 1976).
2006;31:712-6.[PubMed][CrossRef]
Ren
G;
Eiskjaer
S;
Kaspersen
J;
Christensen
FB;
Rasmussen
S. Microdialysis of paraspinal muscle in healthy volunteers and patients underwent posterior lumbar fusion surgery. Eur Spine J.
2009;18:1604-9.[PubMed][CrossRef]
Zander
T;
Rohlmann
A;
Klöckner
C;
Bergmann
G. Influence of graded facetectomy and laminectomy on spinal biomechanics. Eur Spine J.
2003;12:427-34.[PubMed][CrossRef]
Abumi
K;
Panjabi
MM;
Kramer
KM;
Duranceau
J;
Oxland
T;
Crisco
JJ. Biomechanical evaluation of lumbar spinal stability after graded facetectomies. Spine (Phila Pa 1976).
1990;15:1142-7.[PubMed][CrossRef]
Tuite
GF;
Doran
SE;
Stern
JD;
McGillicuddy
JE;
Papadopoulos
SM;
Lundquist
CA;
Oyedijo
DI;
Grube
SV;
Gilmer
HS;
Schork
MA;
Swanson
SE;
Hoff
JT. Outcome after laminectomy for lumbar spinal stenosis. Part II: radiographic changes and clinical correlations. J Neurosurg.
1994;81:707-15.[PubMed][CrossRef]
Tuite
GF;
Stern
JD;
Doran
SE;
Papadopoulos
SM;
McGillicuddy
JE;
Oyedijo
DI;
Grube
SV;
Lundquist
C;
Gilmer
HS;
Schork
MA;
Swanson
SE;
Hoff
JT. Outcome after laminectomy for lumbar spinal stenosis. Part I: clinical correlations. J Neurosurg.
1994;81:699-706. .[PubMed][CrossRef]
Johnsson
KE;
Willner
S;
Johnsson
K. Postoperative instability after decompression for lumbar spinal stenosis. Spine (Phila Pa 1976).
1986;11:107-10.[PubMed][CrossRef]
Bresnahan
L;
Ogden
AT;
Natarajan
RN;
Fessler
RG. A biomechanical evaluation of graded posterior element removal for treatment of lumbar stenosis: comparison of a minimally invasive approach with two standard laminectomy techniques. Spine (Phila Pa 1976).
2009;34:17-23.[PubMed][CrossRef]
Foley
KT;
Smith
MM. Microendoscopic discectomy. Tech Neurosurg.
1997;3:301-7.
Foley
KT;
Smith
MM;
Rampersaud
YR. Microendoscopic approach to far-lateral lumbar disc herniation. Neurosurg Focus.
1999;7:e5.[PubMed][CrossRef]
Perez-Cruet
MJ;
Foley
KT;
Isaacs
RE;
Rice-Wyllie
L;
Wellington
R;
Smith
MM;
Fessler
RG. Microendoscopic lumbar discectomy: technical note. Neurosurgery.
2002;51(
5 Suppl):S129-36.[PubMed]
Schick
U;
Döhnert
J;
Richter
A;
König
A;
Vitzthum
HE. Microendoscopic lumbar discectomy versus open surgery: an intraoperative EMG study. Eur Spine J.
2002;11:20-6.[PubMed][CrossRef]
Muramatsu
K;
Hachiya
Y;
Morita
C. Postoperative magnetic resonance imaging of lumbar disc herniation: comparison of microendoscopic discectomy and Love's method. Spine (Phila Pa 1976).
2001;26:1599-605.[PubMed][CrossRef]
Wu
X;
Zhuang
S;
Mao
Z;
Chen
H. Microendoscopic discectomy for lumbar disc herniation: surgical technique and outcome in 873 consecutive cases. Spine (Phila Pa 1976).
2006;31:2689-94.[PubMed][CrossRef]
Katayama
Y;
Matsuyama
Y;
Yoshihara
H;
Sakai
Y;
Nakamura
H;
Nakashima
S;
Ito
Z;
Ishiguro
N. Comparison of surgical outcomes between macro discectomy and micro discectomy for lumbar disc herniation: a prospective randomized study with surgery performed by the same spine surgeon. J Spinal Disord Tech.
2006;19:344-7.[PubMed][CrossRef]
Cole
JS
4th;
Jackson
TR. Minimally invasive lumbar discectomy in obese patients. Neurosurgery.
2007;61:539-44.[PubMed][CrossRef]
Arts
MP;
Brand
R;
van den Akker
ME;
Koes
BW;
Bartels
RH;
Peul
WC; Leiden-The Hague Spine Intervention Prognostic Study Group (SIPS). Tubular diskectomy vs conventional microdiskectomy for sciatica: a randomized controlled trial. JAMA.
2009;302:149-58.[PubMed][CrossRef]
Ryang
YM;
Oertel
MF;
Mayfrank
L;
Gilsbach
JM;
Rohde
V. Standard open microdiscectomy versus minimal access trocar microdiscectomy: results of a prospective randomized study. Neurosurgery.
2008;62:174-82.[PubMed][CrossRef]
Righesso
O;
Falavigna
A;
Avanzi
O. Comparison of open discectomy with microendoscopic discectomy in lumbar disc herniations: results of a randomized controlled trial. Neurosurgery.
2007;61:545-9.[PubMed][CrossRef]
Weiner
BK;
Walker
M;
Brower
RS;
McCulloch
JA. Microdecompression for lumbar spinal canal stenosis. Spine (Phila Pa 1976).
1999;24:2268-72.[PubMed][CrossRef]
Regev
G;
Taylor
W;
Garfin
SR;
Kim
CW. The use of concurrent bilateral minimally invasive approach for central and neuroforaminal spinal decompression. ; Henderson, NV.
Palmer
S;
Turner
R;
Palmer
R. Bilateral decompressive surgery in lumbar spinal stenosis associated with spondylolisthesis: unilateral approach and use of a microscope and tubular retractor system. Neurosurg Focus.
2002;13:E4.[PubMed]
Palmer
S;
Turner
R;
Palmer
R. Bilateral decompression of lumbar spinal stenosis involving a unilateral approach with microscope and tubular retractor system. J Neurosurg.
2002;97(
2 Suppl):213-7.[PubMed]
Costa
F;
Sassi
M;
Cardia
A;
Ortolina
A;
De Santis
A;
Luccarell
G;
Fornari
M. Degenerative lumbar spinal stenosis: analysis of results in a series of 374 patients treated with unilateral laminotomy for bilateral microdecompression. J Neurosurg Spine.
2007;7:579-86.[PubMed][CrossRef]
Iwatsuki
K;
Yoshimine
T;
Aoki
M. Bilateral interlaminar fenestration and unroofing for the decompression of nerve roots by using a unilateral approach in lumbar canal stenosis. Surg Neurol.
2007;68:487-92.[PubMed][CrossRef]
Khoo
LT;
Fessler
RG. Microendoscopic decompressive laminotomy for the treatment of lumbar stenosis. Neurosurgery.
2002;51(
5 Suppl):S146-54.[PubMed]
Rahman
M;
Summers
LE;
Richter
B;
Mimran
RI;
Jacob
RP. Comparison of techniques for decompressive lumbar laminectomy: the minimally invasive versus the "classic" open approach. Minim Invasive Neurosurg.
2008;51:100-5.[PubMed][CrossRef]
Thomé
C;
Zevgaridis
D;
Leheta
O;
Bäzner
H;
Pöckler-Schöniger
C;
Wöhrle
J;
Schmiedek
P. Outcome after less-invasive decompression of lumbar spinal stenosis: a randomized comparison of unilateral laminotomy, bilateral laminotomy, and laminectomy. J Neurosurg Spine.
2005;3:129-41.[PubMed][CrossRef]
Ikuta
K;
Arima
J;
Tanaka
T;
Oga
M;
Nakano
S;
Sasaki
K;
Goshi
K;
Yo
M;
Fukagawa
S. Short-term results of microendoscopic posterior decompression for lumbar spinal stenosis. Technical note. J Neurosurg Spine.
2005;2:624-33.[PubMed][CrossRef]
Oertel
MF;
Ryang
YM;
Korinth
MC;
Gilsbach
JM;
Rohde
V. Long-term results of microsurgical treatment of lumbar spinal stenosis by unilateral laminotomy for bilateral decompression. Neurosurgery.
2006;59:1264-70.[PubMed]
Ikuta
K;
Tono
O;
Tanaka
T;
Arima
J;
Nakano
S;
Sasaki
K;
Oga
M. Surgical complications of microendoscopic procedures for lumbar spinal stenosis. Minim Invasive Neurosurg.
2007;50:145-9.[PubMed][CrossRef]
Yagi
M;
Okada
E;
Ninomiya
K;
Kihara
M. Postoperative outcome after modified unilateral-approach microendoscopic midline decompression for degenerative spinal stenosis. J Neurosurg Spine.
2009;10:293-9.[PubMed][CrossRef]
Castro-Menéndez
M;
Bravo-Ricoy
JA;
Casal-Moro
R;
Hernández-Blanco
M;
Jorge-Barreiro
FJ. Midterm outcome after microendoscopic decompressive laminotomy for lumbar spinal stenosis: 4-year prospective study. Neurosurgery.
2009;65:100-10, .[PubMed][CrossRef]
Asgarzadie
F;
Khoo
LT. Minimally invasive operative management for lumbar spinal stenosis: overview of early and long-term outcomes. Orthop Clin North Am.
2007;38:387-99, .[PubMed][CrossRef]
Podichetty
VK;
Spears
J;
Isaacs
RE;
Booher
J;
Biscup
RS. Complications associated with minimally invasive decompression for lumbar spinal stenosis. J Spinal Disord Tech.
2006;19:161-6.[PubMed][CrossRef]
Rosen
DS;
O'Toole
JE;
Eichholz
KM;
Hrubes
M;
Huo
D;
Sandhu
FA;
Fessler
RG. Minimally invasive lumbar spinal decompression in the elderly: outcomes of 50 patients aged 75 years and older. Neurosurgery.
2007;60:503-10.[PubMed]
Sasaki
M;
Abekura
M;
Morris
S;
Akiyama
C;
Kaise
K;
Yuguchi
T;
Mori
S;
Iwatsuki
K;
Yoshimine
T. Microscopic bilateral decompression through unilateral laminotomy for lumbar canal stenosis in patients undergoing hemodialysis. J Neurosurg Spine.
2006;5:494-9.[PubMed][CrossRef]
Tomasino
A;
Parikh
K;
Steinberger
J;
Knopman
J;
Boockvar
J;
Härtl
R. Tubular microsurgery for lumbar discectomies and laminectomies in obese patients: operative results and outcome. Spine (Phila Pa 1976).
2009;34:E664-72.[PubMed][CrossRef]
Pao
JL;
Chen
WC;
Chen
PQ. Clinical outcomes of microendoscopic decompressive laminotomy for degenerative lumbar spinal stenosis. Eur Spine J.
2009;18:672-8.[PubMed][CrossRef]
Sasai
K;
Umeda
M;
Maruyama
T;
Wakabayashi
E;
Iida
H. Microsurgical bilateral decompression via a unilateral approach for lumbar spinal canal stenosis including degenerative spondylolisthesis. J Neurosurg Spine.
2008;9:554-9.[PubMed][CrossRef]
Kleeman
TJ;
Hiscoe
AC;
Berg
EE. Patient outcomes after minimally destabilizing lumbar stenosis decompression: the "Port-Hole" technique. Spine (Phila Pa 1976).
2000;25:865-70.[PubMed][CrossRef]
Blume
H;
Rojas
C. Unilateral lumbar interbody fusion (posterior approach) utilizing dowel grafts: experience in over 200 patients. J Neurol Orthop Surg.
1981;2:171.
Cloward
RB. The treatment of ruptured lumbar intervertebral discs by vertebral body fusion. I. Indications, operative technique, after care. J Neurosurg.
1953;10:154-68.[PubMed][CrossRef]
Harms
JG;
Jeszensky
D. The unilateral, transforaminal approach for posterior lumbar interbody fusion. Orthop Traumatol.
1998;6:88-99.
Foley
KT;
Holly
LT;
Schwender
JD. Minimally invasive lumbar fusion. Spine (Phila Pa 1976).
2003;28(
15 Suppl):S26-35.[PubMed]
Hee
HT;
Castro
FP
Jr;
Majd
ME;
Holt
RT;
Myers
L. Anterior/posterior lumbar fusion versus transforaminal lumbar interbody fusion: analysis of complications and predictive factors. J Spinal Disord.
2001;14:533-40.[PubMed][CrossRef]
Whitecloud
TS
3rd;
Roesch
WW;
Ricciardi
JE. Transforaminal interbody fusion versus anterior-posterior interbody fusion of the lumbar spine: a financial analysis. J Spinal Disord.
2001;14:100-3.[PubMed][CrossRef]
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;34:1385-9.[PubMed][CrossRef]
Dhall
SS;
Wang
MY;
Mummaneni
PV. Clinical and radiographic comparison of mini-open transforaminal lumbar interbody fusion with open transforaminal lumbar interbody fusion in 42 patients with long-term follow-up. J Neurosurg Spine.
2008;9:560-5.[PubMed][CrossRef]
Selznick
LA;
Shamji
MF;
Isaacs
RE. Minimally invasive interbody fusion for revision lumbar surgery: technical feasibility and safety. J Spinal Disord Tech.
2009;22:207-13.[PubMed][CrossRef]
Kasis
AG;
Marshman
LA;
Krishna
M;
Bhatia
CK. Significantly improved outcomes with a less invasive posterior lumbar interbody fusion incorporating total facetectomy. Spine (Phila Pa 1976).
2009;34:572-7.[PubMed][CrossRef]
Molinari
RW;
Gerlinger
T. Functional outcomes of instrumented posterior lumbar interbody fusion in active-duty US servicemen: a comparison with nonoperative management. Spine J.
2001;1:215-24.[PubMed][CrossRef]
Fritzell
P;
Hägg
O;
Wessberg
P;
Nordwall
A; Swedish Lumbar Spine Study Group. Lumbar fusion versus nonsurgical treatment for chronic low back pain: a multicenter randomized controlled trial from the Swedish Lumbar Spine Study Group. Spine (Phila Pa 1976).
2001;26:2521-34.[PubMed][CrossRef]
Christensen
FB;
Hansen
ES;
Eiskjaer
SP;
Høy
K;
Helmig
P;
Neumann
P;
Niedermann
B;
Bünger
CE. Circumferential lumbar spinal fusion with Brantigan cage versus posterolateral fusion with titanium Cotrel-Dubousset instrumentation: a prospective, randomized clinical study of 146 patients. Spine (Phila Pa 1976).
2002;27:2674-83.[PubMed][CrossRef]
McAfee
PC;
Regan
JJ;
Geis
WP;
Fedder
IL. Minimally invasive anterior retroperitoneal approach to the lumbar spine. Emphasis on the lateral BAK. Spine (Phila Pa 1976).
1998;23:1476-84.[PubMed][CrossRef]
Ozgur
BM;
Hughes
SA;
Baird
LC;
Taylor
WR. Minimally disruptive decompression and transforaminal lumbar interbody fusion. Spine J.
2006;6:27-33.[PubMed][CrossRef]
Pimenta
L;
Lhamby
J;
Gharzedine
I;
Coutinho
E. XLIF approach for the treatment of adult scoliosis: 2 year follow-up. Spine J.
2004;7(
Suppl):52S-3S.
Saraph
V;
Lerch
C;
Walochnik
N;
Bach
CM;
Krismer
M;
Wimmer
C. Comparison of conventional versus minimally invasive extraperitoneal approach for anterior lumbar interbody fusion. Eur Spine J.
2004;13:425-31.[PubMed][CrossRef]
Regev
GJ;
Chen
L;
Dhawan
M;
Lee
YP;
Garfin
SR;
Kim
CW. Morphometric analysis of the ventral nerve roots and retroperitoneal vessels with respect to the minimally invasive lateral approach in normal and deformed spines. Spine (Phila Pa 1976).
2009;34:1330-5.[PubMed][CrossRef]
Bose
B;
Wierzbowski
LR;
Sestokas
AK. Neurophysiologic monitoring of spinal nerve root function during instrumented posterior lumbar spine surgery. Spine (Phila Pa 1976).
2002;27:1444-50.[PubMed][CrossRef]
Knight
RQ;
Schwaegler
P;
Hanscom
D;
Roh
J. Direct lateral lumbar interbody fusion for degenerative conditions: early complication profile. J Spinal Disord Tech.
2009;22:34-7.[PubMed][CrossRef]
Anand
N;
Baron
EM;
Thaiyananthan
G;
Khalsa
K;
Goldstein
TB. Minimally invasive multilevel percutaneous correction and fusion for adult lumbar degenerative scoliosis: a technique and feasibility study. J Spinal Disord Tech.
2008;21:459-67.[PubMed][CrossRef]
Wright
N. XLIF: the United States experience 2003-2004. Read at the International Meeting on Advanced Spinal Techniques; ; Banff, Canada.
Akbarnia
BA;
Varma
VV;
Bess
S;
Bagheri
R;
Mahjouri
S;
Lhamby
JT;
Hsu
V;
Salari
PA. eXtreme lateral interbody fusion (XLIF) safely improves segmental and global deformity in large adult lumbar scoliosis: preliminary results on 13 patients. Read at the 15th International Meeting on Advanced Spine Techniques (IMAST); ; Hong Kong.
Regev
GJ;
Lee
YP;
Taylor
WR;
Garfin
SR;
Kim
CW. Nerve injury to the posterior rami medial branch during the insertion of pedicle screws: comparison of mini-open versus percutaneous pedicle screw insertion techniques. Spine (Phila Pa 1976).
2009;34:1239-42.[PubMed][CrossRef]
Ringel
F;
Stoffel
M;
Stüer
C;
Meyer
B. Minimally invasive transmuscular pedicle screw fixation of the thoracic and lumbar spine. Neurosurgery.
2006;59(
4 Suppl 2):ONS361-7.[PubMed]
Foley
KT;
Gupta
SK. Percutaneous pedicle screw fixation of the lumbar spine: preliminary clinical results. J Neurosurg.
2002;97:7-12.[PubMed]
Schwender
JD;
Holly
LT;
Rouben
DP;
Foley
KT. Minimally invasive transforaminal lumbar interbody fusion (TLIF): technical feasibility and initial results. J Spinal Disord Tech.
2005;18
Suppl:S1-6.[PubMed][CrossRef]
Eck
JC;
Hodges
S;
Humphreys
SC. Minimally invasive lumbar spinal fusion. J Am Acad Orthop Surg.
2007;15:321-9.[PubMed]
Kosmopoulos
V;
Schizas
C. Pedicle screw placement accuracy: a meta-analysis. Spine (Phila Pa 1976).
2007;32:E111-20.[PubMed][CrossRef]
Merloz
P;
Troccaz
J;
Vouaillat
H;
Vasile
C;
Tonetti
J;
Eid
A;
Plaweski
S. Fluoroscopy-based navigation system in spine surgery. Proc Inst Mech Eng H.
2007;221:813-20.[PubMed]
Assaker
R;
Cinquin
P;
Cotten
A;
Lejeune
JP. Image-guided endoscopic spine surgery: part I. A feasibility study. Spine (Phila Pa 1976).
2001;26:1705-10.[PubMed][CrossRef]
Assaker
R;
Reyns
N;
Pertruzon
B;
Lejeune
JP. Image-guided endoscopic spine surgery: part II: clinical applications. Spine (Phila Pa 1976).
2001;26:1711-8.[PubMed][CrossRef]
Rampersaud
YR;
Foley
KT;
Shen
AC;
Williams
S;
Solomito
M. Radiation exposure to the spine surgeon during fluoroscopically assisted pedicle screw insertion. Spine (Phila Pa 1976).
2000;25:2637-45.[PubMed][CrossRef]
Bindal
RK;
Glaze
S;
Ognoskie
M;
Tunner
V;
Malone
R;
Ghosh
S. Surgeon and patient radiation exposure in minimally invasive transforaminal lumbar interbody fusion. J Neurosurg Spine.
2008;9:570-3.[PubMed][CrossRef]
Kim
CW;
Lee
YP;
Taylor
W;
Oygar
A;
Kim
WK. Use of navigation-assisted fluoroscopy to decrease radiation exposure during minimally invasive spine surgery. Spine J.
2008;8:584-90.[PubMed][CrossRef]
Webb
J;
Gottschalk
L;
Lee
YP;
Garfin
S;
Kim
C. Surgeon perceptions of minimally invasive spine surgery. SAS J.
2008;2:145.[PubMed][CrossRef]
Nowitzke
AM. Assessment of the learning curve for lumbar microendoscopic discectomy. Neurosurgery.
2005;56:755-62.[PubMed][CrossRef]
Villavicencio
AT;
Burneikiene
S;
Bulsara
KR;
Thramann
JJ. Perioperative complications in transforaminal lumbar interbody fusion versus anterior-posterior reconstruction for lumbar disc degeneration and instability. J Spinal Disord Tech.
2006;19:92-7.[PubMed] [CrossRef]