The Development of Minimally Invasive Spine Surgery

Risk of reoperation and infection after percutaneous endoscopic lumbar discectomy and open lumbar discectomy : a nationwide population-based study

AIMS

Open discectomy (OD) is the standard operation for lumbar disc herniation (LDH). Percutaneous endoscopic lumbar discectomy (PELD), however, has shown similar outcomes to OD and there is increasing interest in this procedure. However despite improved surgical techniques and instrumentation, reoperation and infection rates continue and are reported to be between 6% and 24% and 0.7% and 16%, respectively. The objective of this study was to compare the rate of reoperation and infection within six months of patients being treated for LDH either by OD or PELD.

METHODS

In this retrospective, nationwide cohort study, the Korean National Health Insurance database from 1 January 2007 to 31 December 2018 was reviewed. Data were extracted for patients who underwent OD or PELD for LDH without a history of having undergone either procedure during the preceding year. Individual patients were followed for six months through their encrypted unique resident registration number. The primary endpoints were rates of reoperation and infection during the follow-up period. Other risk factors for reoperation and infection were also evalulated.

RESULTS

Out of 549,531 patients, 522,640 had undergone OD (95.11%) and 26,891 patients had undergone PELD (4.89%). Reoperation rates within six months were 2.28% in the OD group, and 5.38% in the PELD group. Infection rates were 1.18% in OD group and 0.83% in PELD group. The risk of reoperation was lower for patients with OD than for patients with PELD (adjusted hazard ratio (HR) 0.38). The risk of infection was higher for patients with OD than for patients undergoing PELD (HR, 1.325).

CONCLUSION

Compared with the OD group, the PELD group showed higher reoperation rates and lower infection rates. Cite this article: Bone Joint J 2021;103-B(8):1392-1399.

Separation surgery for metastatic epidural spinal cord compression: comparison of a minimally invasive versus open approach

OBJECTIVE

The aim of this study was to compare outcomes of separation surgery for metastatic epidural spinal cord compression (MESCC) in patients undergoing minimally invasive surgery (MIS) versus open surgery.

METHODS

A retrospective study of patients undergoing MIS or standard open separation surgery for MESCC between 2009 and 2019 was performed. Both groups received circumferential decompression via laminectomy and a transpedicular approach for partial corpectomy to debulk ventral epidural disease, as well as instrumented stabilization. Outcomes were compared between the two groups.

RESULTS

There were 17 patients in the MIS group and 24 in the open surgery group. The average age of the MIS group was significantly older than the open surgery group (65.5 vs 56.6 years, p < 0.05). The preoperative Karnofsky Performance Scale score of the open group was significantly lower than that of the MIS group, with averages of 63.0% versus 75.9%, respectively (p = 0.02). This was also evidenced by the higher proportion of emergency procedures performed in the open group (9 of 24 patients vs 0 of 17 patients, p = 0.004). The average Spine Instability Neoplastic Score, number of levels fused, and operative parameters, including length of stay, were similar. The average estimated blood loss difference for the open surgery versus the MIS group (783 mL vs 430 mL, p < 0.05) was significant, although the average amount of packed red blood cells transfused was not significantly different (325 mL vs 216 mL, p = 0.39). Time until start of radiation therapy was slightly less in the MIS than the open surgery group (32.8 ± 15.6 days vs 43.1 ± 20.3 days, p = 0.069). Among patients who underwent open surgery with long-term follow-up, 20% were found to have local recurrence compared with 12.5% of patients treated with the MIS technique. No patients in either group developed hardware failure requiring revision surgery.

CONCLUSIONS

MIS for MESCC is a safe and effective approach for decompression and stabilization compared with standard open separation surgery, and it significantly reduced blood loss during surgery. Although there was a trend toward a faster time to starting radiation treatment in the MIS group, both groups received similar postoperative radiotherapy doses, with similar rates of local recurrence and hardware failure. An increased ability to perform MIS in emergency settings as well as larger, prospective studies are needed to determine the potential benefits of MIS over standard open separation surgery.

Endoscopic Spine Surgery in Athletes: Case Series and Review of Literature

BACKGROUND

Degenerative spine disease is common in athletes and can progress to requiring surgical intervention. Traditional open surgical techniques necessitate prolonged recovery time and time away from play. Newly developed endoscopic surgical techniques may promote faster healing and recovery, and increased return to play. The goal of this paper is to summarize the current evidence in return to play after spine surgery and to present our series of 3 athletes who underwent endoscopic spine surgery.

METHODS

A complete search of all PubMed indexed articles pertaining to spine surgery in athletes was conducted. This was supplemented by a 3-patient case series of our own endoscopic spine experience in athletes.

RESULTS

There are no current widely accepted guidelines for return to play after spinal surgery. The best evidence available cites a return to play of 81% at 5.2-8.7 months after traditional open and minimally invasive surgery, and endoscopic surgery produces an average 88% return to play rate at 3 months.

CONCLUSIONS

Although return to play can vary widely, case-based evidence as well as biomechanical principles support endoscopic spine surgery as a viable surgical modality for the treatment of spinal pathologies in athletes.

Two window-minimally invasive lumbar spine surgery (new approach) has a better post operative outcome and less soft tissue damage

Introduction

The purpose of this new approach is to develop a method that is less invasive as well as less traumatic and can provide a better exposure/view of the surgical field. Postoperatively, the patient has less pain, short hospital stay and less use of the postoperative pain control medications. As compared to other minimally invasive spine surgeries this approach results in less soft tissue damage, minimal muscle destruction, less retraction and better surgical outcome.

Methods

In this article authors focus on the new approach that has cost effective benefits as well as short recovery time postoperatively.

Results

Approach is applicable for severe spinal stenosis as compared to other Minimally Invasive Spine Surgery (MISS) techniques that are only applicable for the mild to moderate stenosis or degenerative processes. This plane is avascular plane so no or less bleeding is anticipated from this procedure.

Conclusion

The technique facilitates bilateral canal enlargement through unilateral approach and provides accessibility to the contralateral foramen for decompression with perfect exposure and allows instrumentation through the lateral window with no muscle destruction.

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Minimally Invasive Spine Surgery, Fusion, Two windows approach.

Risk factors predicting less favorable outcomes in endoscopic lumbar discectomies

Background

Endoscopic lumbar discectomy was among the first minimally invasive spine procedures commonly performed. As such, all the benefits of minimal invasion were seen, including less pain, less soft tissue destruction, and faster recovery. While outcomes compare favorably to micro and open discectomy, not all patients fare equally well. This paper examines independent risk factors to assess their correlation to suboptimal outcomes after endoscopic lumbar discectomy.

Methods

Retrospective analysis of clinical outcomes of 55 consecutive patients treated with endoscopic discectomy between June 2018 and March 2019 by the author. Primary outcome measures were postoperative reductions of visual analog score (VAS) for back and leg pain modified MacNab criteria as well as time to narcotic independence. Risk factors examined included smoking, facet disease, adjacent segments disc degeneration, obesity, alcohol abuse, and psychiatric illness.

Results

There were 31 males and 24 females with a mean age of 41.76±12.53. Most patients suffered from contained herniations (49.1%) followed by extruded herniations (18.2%). Follow-up ranged from 6-18 months. The most common surgical levels were L5-S1 level (30.9%), L4-S1 (29.1%), and L4-5 (25.5%). The mean return to work (RTW) was 23.83±26.01 weeks. The average body mass index (BMI) was 29.11±4.75. The average time for narcotic independence was 9.64±7.29 days. MacNab outcomes showed that 47.3% (26/55) had excellent, 36.4% good (20/55), 12.7% fair (7/55), and 3.6% had poor (2/55), respectively. The VAS scores for the back (7.69 to 2.65) and leg (6.78 to 2.65) pain reduced significantly (P<0.0001). Smoking (P=0.048), psychiatric disease (P=0.029), disc herniations larger than 10 mm, facet disease, obesity (BMI >30), diabetes, and alcohol abuse was associated with fair and poor MacNab outcomes.

Conclusions

Endoscopic lumbar discectomy safely and reliably reduces axial pain and radiculopathy from lumbar disc herniations. Risk factors associated with incomplete pain relief are large herniations, obesity, instability, smoking, advanced facet degeneration, and decreased ability to cope with the surgery.

Incidence of Surgical Site Infection After Spine Surgery: A Systematic Review and Meta-analysis

STUDY DESIGN

A systematic review and meta-analysis.

OBJECTIVE

The objective of this study was to investigate the incidence of surgical site infection (SSI) in patients following spine surgery and the rate of microorganisms in these cases.

SUMMARY OF BACKGROUND DATA

Many studies have investigated the incidence and risk factors of SSI following spinal surgery, whereas no meta-analysis studies have been conducted regarding the comprehensive epidemiological incidence of SSI after spine surgery.

METHODS

We searched the PubMed, Embase, and Cochrane Library databases for relevant studies that reported the incidence of SSI after spine surgery, and manually screened reference lists for additional studies. Relevant incidence estimates were calculated. Subgroup analysis, sensitivity analysis, and publication bias assessment were also performed.

RESULTS

Our meta-analysis included 27 studies, with 603 SSI cases in 22,475 patients. The pooled SSI incidence was 3.1%. Subgroup analysis revealed that the incidence of superficial SSI was 1.4% and the incidence of deep SSI was 1.7%. Highest incidence (13.0%) was found in patients with neuromuscular scoliosis among the different indications. The incidences of SSI in cervical, thoracic, and lumbar spine were 3.4%, 3.7%, and 2.7%, respectively. Compared with posterior approach surgery (5.0%), anterior approach showed a lower incidence (2.3%) of SSI. Instrumented surgery had a higher incidence of SSI than noninstrumented surgery (4.4% vs. 1.4%). Patients with minimally invasive surgery (1.5%) had a lower SSI incidence than open surgery (3.8%). Lower incidence of SSI was found when vancomycin powder was applied locally during the surgery (1.9%) compared with those not used (4.8%). In addition, the rates of Staphylococcus aureus, Staphylococcus epidermidis, and methicillin-resistant Staphylococci in microbiological culture results were 37.9%, 22.7%, and 23.1%, respectively.

CONCLUSION

The pooled incidence of SSI following spine surgery was 3.1%. These figures may be useful in the estimation of the probability of SSI following spine surgery.

LEVEL OF EVIDENCE

3.

Devices for minimally-invasive microdiscectomy: current status and future prospects

Introduction: The current gold standard technique for lumbar disc herniation (LDH) is open lumbar microdiscectomy. The use of a tubular retractor system in the microdiscectomy technique can minimize tissue trauma by muscle-splitting sequential dilation during the surgical approach. This review aimed to describe the devices and surgical procedure of this minimally invasive microdiscectomy (MI-MD) and to discuss the pros and cons of the use of tubular retractors.Areas covered: Published medical literatures were extensively reviewed to summarize the practical devices and techniques related to the MI-MD for LDH. The placement of the tubular retractor by gradual muscle-splitting dilation technique may reduce muscle damage and postoperative wound pain. The use of flexible arm may easily change the tube direction and create a wide surgical field.Expert opinion: With reference to published literature, the MI-MD provides comparable clinical outcomes with less tissue trauma and early recovery. Development of devices for MI-MD is still ongoing. Extensive studies, including high-quality randomized trials, are required to establish a more practical and relevant MI-MD technique.

[Minimally invasive spinal surgery: stages of development]

In recent decades, spinal surgery has changed significantly. The active use of modern knowledge of anatomy, various diagnostic modules, specialized surgical equipment and high-tech tools has made it possible to transform classical surgical techniques into a new area of spinal neurosurgery - minimally invasive spine surgery (MISS). Its main goals are to reduce damage to the skin and adjacent tissues, significantly reduce the level of pain, reduce the duration of inpatient treatment and fully restore functional status in the shortest possible time. This article reflects the main criteria for MISS compliance and types of surgical interventions, provides information on the advantages of minimally invasive surgical technologies and their possible disadvantages. Currently, the use of MISS is observed in all areas of vertebrology - for degenerative diseases, tumors, inflammatory and traumatic lesions of the spine. At the same time, minimizing surgical aggression while maximizing the achievement of goal becomes the main rule of modern spinal surgery.

Operative Intervention for Lumbar Foraminal Gunshot Wounds: Case Report and Review of the Literature

Gunshot wounds represent the second most frequent cause of spinal cord injury after vehicular trauma. The thoracic region is most commonly involved, followed by the thoracolumbar spine. Numerous studies have demonstrated that improvement of neurological recovery, especially after decompression surgery, is likely to be seen in lumbosacral spine, but not in the thoracic or cervical spine. Herein, we present a case of a gunshot wound causing lumbar 5^th nerve root compression with neurological deficits that improved remarkably after urgent decompression surgery. This signifies a potential neurological benefit to prompt surgical intervention in lumbar gunshot wounds with radiographic evidence of neural compression. A relevant review of the literature was performed along with discussion, the clinical history, and radiological findings.

Minimally Invasive, Stereotactic, Wireless, Percutaneous Pedicle Screw Placement in the Lumbar Spine: Accuracy Rates With 182 Consecutive Screws

BACKGROUND

Standard fluoroscopic navigation and stereotactic computed tomography-guided lumbar pedicle screw instrumentation traditionally relied on the placement of Kirshner wires (K-wires) to ensure accurate screw placement. The use of K-wires, however, is associated with a risk of morbidity due to potential ventral displacement into the retroperitoneum. We report our experience using a computer image-guided, wireless method for pedicle screw placement. We hypothesize that minimally invasive, wireless pedicle screw placement is as accurate and safe as the traditional technique using K-wires while decreasing operative time and avoiding potential complications associated with K-wires.

METHODS

We conducted a retrospective review of 42 consecutive patients who underwent a stereotactic-guided, wireless lumbar pedicle screw placement. All screws were placed to provide fixation to a variety of interbody fusion constructs including anterior lumbar interbody fusion, lateral interbody fusion, and transforaminal lumbar interbody fusion. The procedures were performed using the O-arm intraoperative imaging system with StealthStation navigation (Medtronic, Memphis, TN) and Medtronic navigated instrumentation. After placing a percutaneous navigation frame into the posterior superior iliac spine or onto an adjacent spinous process, an intraoperative O-arm image was obtained to allow subsequent StealthStation navigation. Para-median incisions were selected to allow precise percutaneous access to the target pedicles. The pedicles were cannulated using either a stereotactic drill or a novel awl-tipped tap along with a low-speed/high-torque power driver. The initial trajectory into the pedicle was recorded on the Medtronic StealthStation prior to removal of the drill or awl-tap, creating a "virtual" K-wire rather than inserting an actual K-wire to allow subsequent tapping and screw insertion. Accurate screw placement is achieved by following the virtual path as an exact computer-aided design model of the screw traversing the pedicle is projected onto the display and by using audible and tactile feedback. A second O-arm scan was obtained to confirm accuracy of screw placement.

RESULTS

A total of 20 women and 22 men (average age = 56 years) underwent a total of 182 pedicle screw placements using the stereotactic, wireless technique. The total breach rate was 9.9%, with a clinically significant breach rate of 0% (defined as >2 mm medial breach or >4 mm lateral breach) and a clinical complication rate of 0%.

CONCLUSIONS

Wireless, percutaneous placement of lumbar pedicle screws using computed tomography-guided stereotactic navigation is a safe, reproducible technique with very high accuracy rates.

Risk factors for surgical site infection after lumbar laminectomy and/or discectomy for degenerative diseases in adults: A prospective multicenter surveillance study with registry of 4027 cases

Surgical site infection (SSI) is a significant complication after spinal surgery and is associated with increased hospital length of stay, high healthcare costs, and poor patient outcomes. Accurate identification of risk factors is essential to develop strategies to prevent wound infections. The aim of this prospective multicenter study was to determine the independent factors associated with SSI in posterior lumbar surgeries without fusion (laminectomy and/or herniotomy) for degenerative diseases in adult patients. From July 2010 to June 2014, we conducted a prospective multicenter surveillance study in adult patients who developed SSI after undergoing lumbar laminectomy and/or discectomy in ten participating hospitals. Detailed patient and operative characteristics were prospectively recorded using a standardized data collection format. SSI was based on the Centers for Disease Control and Prevention definition. A total of 4027 consecutive adult patients were enrolled, of which 26 (0.65%) developed postoperative SSI. Multivariate regression analysis indicated two independent factors. An operating time >2 h (P = 0.0095) was a statistically significant independent risk factor, whereas endoscopic tubular surgery (P = 0.040) was a significant independent protective factor. Identification of these associated factors may contribute to surgeons’ awareness of the risk factors for SSI and could help counsel the patients on the risks associated with lumbar laminectomy and/or discectomy. Furthermore, this study’s findings could be used to develop protocols to decrease SSI risk. To the best of our knowledge, this is the first prospective multicenter study that identified endoscopic tubular surgery as an independent protective factor against SSI after lumbar posterior surgery without fusion.

In-hospital complication rate following microendoscopic versus open lumbar laminectomy: a propensity score-matched analysis

BACKGROUND CONTEXT

The incidence of postoperative complications after microendoscopic laminectomy (MEL) has not been compared with that after open laminectomy in a large study, so it is not clear whether MEL is a safer procedure.

PURPOSE

The objective of this study was to compare postoperative morbidity and mortality following lumbar laminectomy between patients treated with MEL and with open laminectomy.

STUDY DESIGN

This is a retrospective cohort study with propensity score-matched analysis.

PATIENT SAMPLE

Data of patients who underwent elective spinal surgery between July 2010 and March 2013 were extracted from the Diagnosis Procedure Combination database, a nationwide inpatient database in Japan.

OUTCOME MEASURES

Clinical outcomes included length of hospital stay, occurrence of major complications (cardiac events, respiratory complications, pulmonary embolism, stroke, and acute renal failure), surgical site infection (SSI), postoperative delirium, and in-hospital death.

MATERIALS AND METHODS

Propensity score matching was performed to adjust for measured confounding factors, including patient age, sex, Charlson Comorbidity Index, body mass index, smoking status, blood transfusion, duration of anesthesia, number of operated disc levels, and type of hospital and hospital volumes. The clinical outcomes of one-to-one propensity-matched pairs of the MEL and the open laminectomy groups were compared.

RESULTS

Of 23,317 patients identified in the database, 1,536 underwent MEL (6.6%). By one-to-one propensity score matching, 1,536 pairs were selected. The distributions of patient backgrounds were closely balanced between the MEL and the open laminectomy groups. An analysis of 1,536 pairs revealed that there was a significantly lower incidence of major postoperative complications in those who underwent MEL (1.0% vs. 2.8% for open laminectomy, risk difference 1.8%, 95% confidence interval [CI] 0.9%-2.9%), SSI (0.5% vs. 1.6% for open laminectomy, risk difference 1.1%, 95% CI 0.4%-1.9%), and postoperative delirium (1.1% vs. 2.3% for open laminectomy, risk difference1.2%, 95% CI 0.3%-2.1%). The length of hospital stay was significantly shorter in those treated with MEL (12 days vs. 16 days for open laminectomy, p<.001). There was no significant difference in in-hospital mortality between the groups.

CONCLUSIONS

Patients who underwent MEL were significantly less likely to experience major postoperative complications and were less likely to develop SSI and postoperative delirium than those who underwent open laminectomy.

Clinical and Radiological Comparison between Three Different Minimally Invasive Surgical Fusion Techniques for Single-Level Lumbar Isthmic and Degenerative Spondylolisthesis: Minimally Invasive Surgical Posterolateral Fusion versus Minimally Invasive Surgical Transforaminal Lumbar Interbody Fusion versus Midline Lumbar Fusion

Study Design

Retrospective cohort study.

Purpose

Comparison between three different minimally invasive surgical (MIS) fusion techniques for single-level lumbar spondylolisthesis.

Overview of Literature

There has been an increase in the development and utilization of MIS techniques for lumbar spine fusion. No study has compared the efficacy of MIS-posterolateral fusion (MIS-PLF), MIS-transforaminal lumbar interbody fusion (MIS-TLIF), and midline lumbar fusion (MIDLF) with modified cortical bone trajectory screws for lumbar spondylolisthesis.

Methods

Fifty-nine patients with single-level lumbar spondylolisthesis and a minimum follow-up period of 1 year were included in this study. The MIS-PLF, MIS-TLIF, and MIDLF groups included 22, 15, and 22 patients, respectively. The average age of the groups was 70.6, 49.3, and 62.7 years, respectively. The evaluation parameters were operation time, intraoperative bleeding, serum C-reactive protein (CRP) value, creatine kinase (CK) value, and overall functional outcome as per the Japanese Orthopedic Association Back Pain Evaluation Questionnaire (JOABPEQ) score. The changes in the lumbar lordosis angle (LLA), segmental disc angle (SDA), and disc height were measured. Fusion rate, screw loosening, and loss of correction were also assessed.

Results

MIDLF showed a significantly shorter operation time (111 min), less bleeding amount (112.5 mL), and lower values of CRP and CK than the other two techniques. There was no significant difference in the JOABPEQ scores of the three groups. MIDLF resulted in a greater increase in the LLA and SDA postoperatively. MIDLF and MIS-TLIF resulted in a significant increase in the middle disc height compared with MIS-PLF. MIDLF showed a lower loss of correction after 6 months postoperatively (2.6%) than MIS-PLF (5.2%) and MIS-TLIF (4.2%). The fusion rate was 100% in the MIDLF and MIS-TLIF groups and 90% in the MIS-PLF group. Screw loosening occurred in 10% of the MIS-PLF cases, 7.14% of the MIS-TLIF cases, and 4.76% of the MIDLF cases.

Conclusions

MIDLF was the least invasive, and there was no significant difference between the three groups in terms of fusion, screw loosening, and clinical outcomes.

Is MIS-TLIF superior to open TLIF in obese patients?: A systematic review and meta-analysis

PURPOSE

Obesity is a global health problem. It increases the risk of surgical complications and re-operations. While both MIS-TLIF and O-TLIF are reported to have comparably good long-term outcomes for non-obese patients, no consensus has been reached for obese patients.

METHODS

A comprehensive search of the published literature was performed: PubMed, Scopus, Web of Science and Cochrane Central Register of Controlled Trials database in accordance to the PRISMA 2009 checklist. Data were collected with attention to baseline demographics, intra-operative blood loss, duration of surgery, surgical complications, hospitalization stay, VAS and Oswestry disability index (ODI) pre- and postoperatively.

RESULTS

A total of 863 abstracts were identified from the databases, of which 4 articles were included in the meta-analysis. A total of 430 patients were identified, of which 217(50.5%) underwent the O-TLIF, while 213(49.5%) underwent MIS-TLIF. One hundred and ninety-four (45.1%) patients were males, while 236(54.9%) were females. The average age was 54.8 ± 12.0 years. The pooled BMI was 33.4 ± 4.7 for the open-TLIF group, and 32.7 ± 3.9 for MIS-TLIF group (p = 0.22). When comparing O-TLIF to MIS-TLIF: Patients who underwent O-TLIF had 383 mls more blood loss (95% CI: 329.5-437.4, p < 0.00001), 1.2-day longer hospitalization stay (95% CI: 0.80-1.62, p < 0.00001) and 3.8 times higher risk of dural tear (95% CI: 1.61-9.87, p = 0.003) when compared to MIS-TLIF patients. A trend toward higher postoperative wound infection rates (O-TLIF: 4.5%, MIS-TLIF: 2.4%) and an inferior improvement in ODI score (O-TLIF: 39.3, MIS-TLIF: 44.1) was found in O-TLIF patients when compared to MIS-TLIF patients. However, these were not statistically significant.

CONCLUSION

MIS-TLIF is safe and may be a better option for lumbar fusion in obese patients. These slides can be retrieved under Electronic Supplementary Material.

[Decompression by mini-open posterior approach assisted with microscope for thoracolumbar burst fracture with severe spinal canal stenosis]

Objective

To investigate the effectiveness of posterior microscopic mini-open technique (MOT) decompression in patients with severe spinal canal stenosis resulting from thoracolumbar burst fractures.

Methods

The clinical data of 28 patients with severe spinal canal stenosis caused by thoracolumbar burst fractures, who were treated by posterior microscopic MOT, which performed unilateral or bilateral laminectomy, poking reduction, intervertebral bone graft via spinal canal, and percutaneous pedicle screw fixation between January 2014 and January 2016 were retrospectively analyzed. There were 21 males and 7 females with a mean age of 42.1 years (range, 16-61 years). The involved segments included T 11 in 1 case, T 12 in 4 cases, L 1 in 14 cases, and L 2 in 9 cases. According to AO classification, there were 19 cases of type A3, 9 of type A4. According to American Spinal Injury Association (ASIA) grading, 12 cases were grade C, 13 grade D, and 3 grade E. The time between injury and operation was 3-7 days (mean, 3.6 days). To evaluate effectiveness, the changes in the visual analogue scale (VAS), percentage of anterior height of injured vertebrae, Cobb angle, rate of spinal compromise (RSC), and ASIA grading were analyzed.

Results

All patients were performed procedures successfully. The operation time was 135-323 minutes (mean, 216.4 minutes). The intraoperative blood loss was 80-800 mL (mean, 197.7 mL). The hospitalization time was 10-25 days (mean, 12.5 days). The incisions healed primarily, without wound infection, cerebrospinal fluid leakage, or other early complications. All the 28 patients were followed up 12-24 months (mean, 16.5 months). No breakage or loosening of internal fixation occurred. All fractures healed, and the healing time was 3-12 months (mean, 6.5 months). Compared with preoperative ones, the percentage of anterior height of injured vertebrae, Cobb angle, and RSC at immediate after operation and at last follow-up and the VAS scores at 1 day after operation and at last-follow were significantly improved ( P<0.05). There was no significant difference in the percentage of anterior height of injured vertebrae and Cobb angle between at immediate after operation and at last follow-up ( P>0.05). But the RSC at immediate after operation and VSA score at 1 day after operation were significantly improved when compared with those at last follow-up ( P<0.05). The ASIA grading at last follow-up was 1 case of grade C, 14 grade D, and 13 grade E, which was significantly improved when compared with preoperative ones ( Z=3.860, P=0.000).

Conclusion

MOT is an effective and minimal invasive treatment for thoracolumbar AO type A3 and A4 burst fractures with severe spinal canal stenosis, and it is beneficial to early rehabilitation for patients.

Divergent Bilateral Posterior Lumbar Interbody Fusion with Cortical Screw Fixation: Description of New Trajectory for Interbody Technique from Midline Exposure

BACKGROUND

A major drawback to use of cortical bone trajectory pedicle screws (CBTPSs) with traditional posterior lumbar interbody fusion (PLIF) and transforaminal lumbar interbody fusion grafts is that traditional graft insertion trajectories require wider posterior exposure. This wider exposure, beyond the limits otherwise required for CBTPS placement, negates a primary benefit of CBTPS fixation. The aim of this study was to define an alternative surgical technique for interbody graft placement that, when used in conjunction with CBTPS fixation, permits both minimal soft tissue dissection and optimal graft placement.

METHODS

A team of neurosurgeons specializing in treatment of spinal pathologies developed a surgical technique for insertion of bilateral PLIF grafts that complements the principles of CBTPS fixation. This technique is illustrated in a patient undergoing lumbosacral decompression, CBTPS fixation, and 3-column arthrodesis.

RESULTS

The described technique uses a divergent trajectory of bilateral PLIF grafts rather than the traditional parallel or convergent trajectories.

CONCLUSIONS

By aiming medially to laterally with the interbody graft, one recapitulates many advantages of CBTPSs, including avoidance of wide tissue dissection, greater intergraft volume available for bone grafting, and greater graft coverage of the hypophyseal ring. The prospective collection of outcome data for patients who undergo lumbosacral fusion using the divergent PLIF technique is ongoing.

Minimally Invasive Versus Open Laminectomy/Discectomy, Transforaminal Lumbar, and Posterior Lumbar Interbody Fusions: A Systematic Review

Minimally invasive spine surgeries (MISS) are becoming increasingly favored as alternatives to open spine procedures because of the reduced blood loss, postoperative pain, and recovery time. Studies have shown mixed results regarding the efficacy and safety of minimally invasive procedures compared to the traditional, open counterparts. The objectives of this systematic analysis are to compare clinical outcomes between the three MISS and open procedures: (1) laminectomy/discectomy, (2) transforaminal lumbar interbody fusion (TLIF), and (3) posterior lumbar interbody fusion (PLIF). The Cochrane and PubMed databases were queried according to the preferred reporting items for systematic review and meta-analyses (PRISMA) statement. The primary outcome measures included the visual analog scale (VAS), the Oswestry disability index (ODI), and blood loss. A total of 32 studies were included in the analysis. Of the three procedures investigated, only MISS TLIF showed significantly improved VAS for leg pain (p = 0.02), ODI (p = 0.05), and reduced blood loss (p = 0.005). MISS-laminectomy/discectomy, TLIF, and PLIF appear to be similar in terms of postoperative pain and perioperative blood loss. MISS TLIF is perhaps more effective in specific outcome measures and results in less intraoperative blood loss than open TLIF.

Biomechanical comparison of multilevel lateral interbody fusion with and without supplementary instrumentation: a three-dimensional finite element study

Background

Lateral lumbar interbody fusion (LLIF) is a popular, minimally invasive technique that is used to address challenging multilevel degenerative spinal diseases. It remains controversial whether supplemental instrumentation should be added for multilevel LLIF. In this study, we compared the kinematic stability afforded by stand-alone lateral cages with those supplemented by bilateral pedicle screws and rods (PSR), unilateral PSR, or lateral plate (LP) fixation using a finite-element (FE) model of a multi-level LLIF construct with simulated osteoporosis. Additionally, to evaluate the prospect of cage subsidence, the stress change characteristics were surveyed at cage-endplate interfaces.

Methods

A nonlinear 3-dimensional FE model of the lumbar spine (L2 to sacrum) was used. After validation, four patterns of instrumented 3-level LLIF (L2-L5) were constructed for this analysis: (a) 3 stand-alone lateral cages (SLC), (b) 3 lateral cages with lateral plate and two screws (parallel to endplate) fixated separately (LPC), (c) 3 lateral cages with bilateral pedicle screw and rod fixation (LC + BPSR), and (d) 3 lateral cages with unilateral pedicle and rod fixation (LC + UPSR). The segmental and overall range of motion (ROM) of each implanted condition were investigated and compared with the intact model. The peak von Mises stresses upon each (superior) endplate and the stress distribution were used for analysis.

Results

BPSR provided the maximum reduction of ROM among the configurations at every plane of motion (66.7–90.9% of intact spine). UPSR also provided significant segmental ROM reduction (45.0–88.3%). SLC provided a minimal restriction of ROM (10.0–75.1%), and LPC was found to be less stable than both posterior fixation (23.9–86.2%) constructs. The construct with stand-alone lateral cages generated greater endplate stresses than did any of the other multilevel LLIF models. For the L3, L4 and L5 endplates, peak endplate stresses caused by the SLC construct exceeded the BPSR group by 52.7, 63.8, and 54.2% in flexion, 22.3, 40.1, and 31.4% in extension, 170.2, 175.1, and 134.0% in lateral bending, and 90.7, 45.5, and 30.0% in axial rotation, respectively. The stresses tended to be more concentrated at the periphery of the endplates.

Conclusions

SLC and LPC provided inadequate ROM restriction for the multilevel LLIF constructs, whereas lateral cages with BPSR or UPSR fixation provided favorable biomechanical stability. Moreover, SLC generated significantly higher endplate stress compared with supplemental instrumentation, which may have increased the risk of cage subsidence. Further biomechanical and clinical studies are required to validate our FEA findings.

Electronic supplementary material

The online version of this article (doi:10.1186/s12891-017-1387-6) contains supplementary material, which is available to authorized users.

Does Minimally Invasive Spine Surgery Minimize Surgical Site Infections?

STUDY DESIGN

Retrospective review of prospectively collected data.

PURPOSE

To evaluate the incidence of surgical site infections (SSIs) in minimally invasive spine surgery (MISS) in a cohort of patients and compare with available historical data on SSI in open spinal surgery cohorts, and to evaluate additional direct costs incurred due to SSI.

OVERVIEW OF LITERATURE

SSI can lead to prolonged antibiotic therapy, extended hospitalization, repeated operations, and implant removal. Small incisions and minimal dissection intrinsic to MISS may minimize the risk of postoperative infections. However, there is a dearth of literature on infections after MISS and their additional direct financial implications.

METHODS

All patients from January 2007 to January 2015 undergoing posterior spinal surgery with tubular retractor system and microscope in our institution were included. The procedures performed included tubular discectomies, tubular decompressions for spinal stenosis and minimal invasive transforaminal lumbar interbody fusion (TLIF). The incidence of postoperative SSI was calculated and compared to the range of cited SSI rates from published studies. Direct costs were calculated from medical billing for index cases and for patients with SSI.

RESULTS

A total of 1,043 patients underwent 763 noninstrumented surgeries (discectomies, decompressions) and 280 instrumented (TLIF) procedures. The mean age was 52.2 years with male:female ratio of 1.08:1. Three infections were encountered with fusion surgeries (mean detection time, 7 days). All three required wound wash and debridement with one patient requiring unilateral implant removal. Additional direct cost due to infection was $2,678 per 100 MISS-TLIF. SSI increased hospital expenditure per patient 1.5-fold after instrumented MISS.

CONCLUSIONS

Overall infection rate after MISS was 0.29%, with SSI rate of 0% in non-instrumented MISS and 1.07% with instrumented MISS. MISS can markedly reduce the SSI rate and can be an effective tool to minimize hospital costs.

Lumbar microdiscectomy complication rates: a systematic review and meta-analysis

OBJECT Lumbar microdiscectomy and its various minimally invasive surgical techniques are seeing increasing popularity, but a systematic review of their associated complications has yet to be performed. The authors sought to identify all prospective clinical studies reporting complications associated with lumbar open microdiscectomy, microendoscopic discectomy (MED), and percutaneous microdiscectomy. METHODS The authors conducted MEDLINE, Scopus, Web of Science, and Embase database searches for randomized controlled trials and prospective cohort studies reporting complications associated with open, microendoscopic, or percutaneous lumbar microdiscectomy. Studies with fewer than 10 patients and published before 1990 were excluded. Overall and interstudy median complication rates were calculated for each surgical technique. The authors also performed a meta-analysis of the reported complications to assess statistical significance across the various surgical techniques. RESULTS Of 9504 articles retrieved from the databases, 42 met inclusion criteria. Most studies screened were retrospective case series, limiting the number of studies that could be included. A total of 9 complication types were identified in the included studies, and these were analyzed across each of the surgical techniques. The rates of any complication across the included studies were 12.5%, 13.3%, and 10.8% for open, MED, and percutaneous microdiscectomy, respectively. New or worsening neurological deficit arose in 1.3%, 3.0%, and 1.6% of patients, while direct nerve root injury occurred at rates of 2.6%, 0.9%, and 1.1%, respectively. Hematoma was reported at rates of 0.5%, 1.2%, and 0.6%, respectively. Wound complications (infection, dehiscence, orseroma) occurred at rates of 2.1%, 1.2%, and 0.5%, respectively. The rates of recurrent disc complications were 4.4%, 3.1%, and 3.9%, while reoperation was indicated in 7.1%, 3.7%, and 10.2% of operations, respectively. Meta-analysis calculations revealed a statistically significant higher rate of intraoperative nerve root injury following percutaneous procedures relative to MED. No other significant differences were found. CONCLUSIONS This review highlights complication rates among various microdiscectomy techniques, which likely reflect real-world practice and conceptualization of complications among physicians. This investigation sets the framework for further discussions regarding microdiscectomy options and their associated complications during the informed consent process.

Ablation of porcine ligamentum flavum with Ho:YAG, q-switched Ho:YAG, and quadrupled Nd:YAG lasers

BACKGROUND AND OBJECTIVES

Ligamentum flavum (LF) is a tough, rubbery connective tissue providing a portion of the ligamentous stability to the spinal column, and in its hypertrophied state forms a significant compressive pathology in degenerative spinal stenosis. The interaction of lasers and this biological tissue have not been thoroughly studied. Technological advances improving endoscopic surgical access to the spinal canal makes selective removal of LF using small, flexible tools such as laser-coupled fiber optics increasingly attractive for treatment of debilitating spinal stenosis. Testing was performed to assess the effect of Ho:YAG, Q-switched Ho:YAG, and frequency quadrupled Nd:YAG lasers on samples of porcine LF. The objective was to evaluate the suitability of these lasers for surgical removal of LF.

STUDY DESIGN/MATERIALS AND METHODS

LF was resected from porcine spine within 2 hours of sacrifice and stored in saline until immediately prior to laser irradiation, which occurred within an additional 2 hours. The optical absorbance of a sample was measured over the spectral band from 190 to 2,360 nm both before and after dehydration. For the experiments using the Ho:YAG (λ = 2,080 nm, tp  = 140 µs, FWHM) and Q-Switched Ho:YAG (λ = 2,080 nm, tp  = 260 ns, FWHM) lasers, energy was delivered to the LF through a laser-fiber optic with 600 µm core and NA = 0.39. For the experiment using the frequency quadrupled Nd:YAG laser (λ = 266 nm, tp  = 5 ns FWHM), rather than applying the laser energy through a laser-fiber, the energy was focused through an aperture and lens directly onto the LF. Five experiments were conducted to evaluate the effect of the given lasers on LF. First, using the Ho:YAG laser, the single-pulse laser-hole depth versus laser fluence was measured with the laser-fiber in direct contact with the LF (1 g force) and with a standoff distance of 1 mm between the laser-fiber face and the LF. Second, with the LF remaining in situ and the spine bisected along the coronal plane, the surface temperature of the LF was measured with an IR camera during irradiation with the Ho:YAG laser, with and without constant saline flush. Third, the mass loss was measured over the course of 450 Ho:YAG pulses. Fourth, hole depth and temperature were measured over 30 pulses of fixed fluence from the Ho:YAG and Q-Switched Ho:YAG lasers. Fifth, the ablation rate and surface temperature were measured as a function of fluence from the Nd:YAG laser. Several LF staining and hole-depth measurement techniques were also explored.

RESULTS

Aside from the expected absorbance peaks corresponding to the water in the LF, the most significant peaks in absorbance were located in the spectral band from 190 to 290 nm and persisted after the tissue was dehydrated. In the first experiment, using the Ho:YAG laser and with the laser-fiber in direct contact with the LF, the lowest single-pulse fluence for which LF was visibly removed was 35 J/cm(2) . Testing was conducted at 6 fluences between 35 and 354 J/cm(2) . Over this range the single-pulse hole depth was shown to be near linear (R(2)  = 0.9374, M = 1.6), ranging from 40 to 639 µm (N = 3). For the case where the laser-fiber face was displaced 1 mm from the LF surface, the lowest single-pulse fluence for which tissue was visibly removed was 72 J/cm(2) . Testing was conducted at 4 energy densities between 72 and 180 J/cm(2) . Over this range the single-pulse hole depth was shown to be near linear (R(2)  = 0.8951, M = 1.4), ranging from 31 to 220 µm (N = 3). In the second experiment, with LF in situ, constant flushing with room temperature saline was shown to drastically reduce surface temperature during exposure to Ho:YAG at 5 Hz with the laser-fiber in direct contact with the LF. Without saline, over 1 minute of treatment with a per-pulse fluence of 141 mJ/cm(2) , the average maximum surface temperature measured 110°C. With 10 cc's of saline flushed over 1 minute and a per-pulse laser fluence of 212 mJ/cm(2) , the average maximum surface temperature was 35°C. In the third experiment, mass loss was shown to be linear over 450 pulses of 600 mJ from the Ho:YAG laser (212 J/cm(2) , direct contact, N = 4; 108 J/cm(2) , 1 mm standoff, N = 4). With the laser-fiber in direct contact, an average of 53 mg was removed (R(2)  = 0.996, M = 0.117) and with 1 mm laser-fiber standoff, an average of 44 mg was removed (R(2)  = 0.9988, M = 0.097). In the fourth experiment, 30 pulses of the Ho:YAG and Q-Switched Ho:YAG lasers at 1 mm standoff, and 5 Hz produced similar hole depths for the tested fluences of 9 J/cm(2) (151 and 154 µm, respectively) and 18 J/cm(2) (470 and 442 µm, respectively), though the Ho:YAG laser produced significantly more carbonization around the rim of the laser-hole. The increased carbonization was corroborated by higher measured LF temperature. In all tests with the Ho:YAG and Q-Switched Ho:YAG, an audible photo-acoustic affect coincided with the laser pulse. In the fifth experiment, with the frequency quadrupled Nd:YAG laser at 15 Hz for 450 pulses, ablation depth per pulse was shown to be linear for the fluence range of 0.18 - 0.73 J/cm(2) (R(2)  = 0.989, M = 2.4). There was no noticeable photo-acoustic effect nor charring around the rim of the laser-hole.

CONCLUSION

The Ho:YAG, Q-Switched Ho:YAG, and frequency quadrupled Nd:YAG lasers were shown to remove ligamentum flavum (LF). A single pulse of the Ho:YAG laser was shown to cause tearing of the tissue and a large zone of necrosis surrounding the laser-hole. Multiple pulses of the Ho:YAG and Q-Switched Ho:YAG lasers caused charring around the rim of the laser-hole, though the extent of charring was more extensive with the Ho:YAG laser. Charring caused by the Ho:YAG laser was shown to be mitigated by continuously flushing the affected LF with saline during irradiation. The Nd:YAG laser was shown to ablate LF with no gross visible indication of thermal damage to surrounding LF.

Mast Quadrant-assisted minimally invasive modified transforaminal lumbar interbody fusion: single incision versus double incision

BACKGROUND

The concept of minimally invasive techniques is to make every effort to reduce tissue damage. Certainly, reducing skin incision is an important part of these techniques. This study aimed to investigate the clinical feasibility of Mast Quadrant-assisted modified transforaminal lumbar interbody fusion (TLIF) with a small single posterior median incision.

METHODS

During the period of March 2011 to March 2012, 34 patients with single-segment degenerative lumbar disease underwent the minimally invasive modified TLIF assisted by Mast Quadrant with a small single posterior median incision (single incision group). The cases in this group were compared to 37 patients with single-segment degenerative lumbar disease in the double incision group. The perioperative conditions of patients in these two groups were statistically analyzed and compared. The Oswestry Disability Index (ODI) scores, Visual Analog Scale (VAS) scores, and sacrospinalis muscle damage evaluation indicators before operation and 3, 12 months postoperation were compared.

RESULTS

A total of 31 and 35 cases in the single incision and double incision groups, respectively, completed at least 12 months of systemic follow-up. The differences in perioperative conditions between the two groups were not statistically significant. The incision length of the single incision group was significantly shorter than that of the double incision group (P < 0.01). The ODI and VAS scores of patients in both groups improved significantly at 3 and 12 months postoperation. However, these two indicators at 3 and 12 months postoperation and the sacrospinalis muscle damage evaluation indicators at 3 months postoperation did not differ significantly between the two groups (P ≥ 0.05).

CONCLUSIONS

Mast Quadrant-assisted modified TLIF with a small single posterior median incision has excellent clinical feasibility compared to minimally invasive TLIF with a double paramedian incision.

Complications in adult spinal deformity surgery: an analysis of minimally invasive, hybrid, and open surgical techniques

OBJECT

It is hypothesized that minimally invasive surgical techniques lead to fewer complications than open surgery for adult spinal deformity (ASD). The goal of this study was to analyze matched patient cohorts in an attempt to isolate the impact of approach on adverse events.

METHODS

Two multicenter databases queried for patients with ASD treated via surgery and at least 1 year of follow-up revealed 280 patients who had undergone minimally invasive surgery (MIS) or a hybrid procedure (HYB; n = 85) or open surgery (OPEN; n = 195). These patients were divided into 3 separate groups based on the approach performed and were propensity matched for age, preoperative sagittal vertebral axis (SVA), number of levels fused posteriorly, and lumbar coronal Cobb angle (CCA) in an attempt to neutralize these patient variables and to make conclusions based on approach only. Inclusion criteria for both databases were similar, and inclusion criteria specific to this study consisted of an age > 45 years, CCA > 20°, 3 or more levels of fusion, and minimum of 1 year of follow-up. Patients in the OPEN group with a thoracic CCA > 75° were excluded to further ensure a more homogeneous patient population.

RESULTS

In all, 60 matched patients were available for analysis (MIS = 20, HYB = 20, OPEN = 20). Blood loss was less in the MIS group than in the HYB and OPEN groups, but a significant difference was only found between the MIS and the OPEN group (669 vs 2322 ml, p = 0.001). The MIS and HYB groups had more fused interbody levels (4.5 and 4.1, respectively) than the OPEN group (1.6, p < 0.001). The OPEN group had less operative time than either the MIS or HYB group, but it was only statistically different from the HYB group (367 vs 665 minutes, p < 0.001). There was no significant difference in the duration of hospital stay among the groups. In patients with complete data, the overall complication rate was 45.5% (25 of 55). There was no significant difference in the total complication rate among the MIS, HYB, and OPEN groups (30%, 47%, and 63%, respectively; p = 0.147). No intraoperative complications were reported for the MIS group, 5.3% for the HYB group, and 25% for the OPEN group (p < 0.03). At least one postoperative complication occurred in 30%, 47%, and 50% (p = 0.40) of the MIS, HYB, and OPEN groups, respectively. One major complication occurred in 30%, 47%, and 63% (p = 0.147) of the MIS, HYB, and OPEN groups, respectively. All patients had significant improvement in both the Oswestry Disability Index (ODI) and visual analog scale scores after surgery (p < 0.001), although the MIS group did not have significant improvement in leg pain. The occurrence of complications had no impact on the ODI.

CONCLUSIONS

Results in this study suggest that the surgical approach may impact complications. The MIS group had significantly fewer intraoperative complications than did either the HYB or OPEN groups. If the goals of ASD surgery can be achieved, consideration should be given to less invasive techniques.

Infection rate after minimally invasive noninstrumented spinal surgery based on 4350 procedures

STUDY DESIGN

Retrospective review of a prospectively collected database.

OBJECTIVE

To assess the rate of postoperative infection associated with minimally invasive noninstrumented spinal surgery.

SUMMARY OF BACKGROUND DATA

Infection after spinal surgery results in significant morbidity, extended hospital stay, and significant costs. Minimally invasive spinal techniques require smaller incisions and less dissection, minimizing the risk of postoperative infection.

METHODS

Inclusion criteria were patients undergoing posterior spinal surgery using a tubular retractor system with the aid of operative microscope between June 1998 and November 2013. The analysis revealed a total number of 4350 procedures performed in 4037 patients (mean age=53.2 yr). Sixty percent of the patients were male. The majority of procedures were performed in the lumbar spine (98.4%), and the indication was mostly degenerative in nature (96.9%). The databases were then reviewed for any infectious complications.

RESULTS

Postoperative infection was recorded in 4 patients (0.09%). All of them occurred in the lumbar region after discectomy. These patients presented with discitis and underwent revision in the form of open debridement and fusion. The time lapse between the index surgery and revision was 56 days. All 4 patients recovered, with a mean follow-up of 7.5 years.

CONCLUSION

Infection rate after posterior transtubular microscopic assisted spinal surgery is very low (0.09%). Surgical debridement with fusion was the method of choice in treating such complications. This minimally invasive technique reduces markedly the risk of postoperative infection when compared with other large series published in the literature.

LEVEL OF EVIDENCE

4.

Intraoperative navigation in minimally invasive transforaminal lumbar interbody fusion and lateral interbody fusion

Advances in spine surgery continue to provide increased safety and efficacy for a wide range of disorders. Minimally invasive techniques have revolutionized many of the ways spinal disorders are treated, offering optimal outcomes with minimal complications on the premise of avoiding unnecessary traumatic muscle dissection and disruption. Percutaneous spine surgery is mostly, if not purely, fluoroscopically based. Hence, there is an increased amount of radiation exposure to the patient, surgeons, and the operating-room team. To address this issue, navigation-based percutaneous techniques have evolved with the aim of reducing the radiation exposure while achieving all goals of minimally invasive spine surgery.

Full-endoscopic interlaminar removal of chronic lumbar epidural hematoma after spinal manipulation

Background:

Spinal manipulation is widely used for low back pain treatments. Complications associated with spinal manipulation are seen. Lumbar epidural hematoma (EDH) is one of the complications reported in the literature. If lumbar chronic EDH symptoms are present, which are similar to those of a herniated nucleus pulposus, surgery may be considered if medical treatment fails. Percutaneous endoscopic discectomy utilizing an interlaminar approach can be successfully applied to those with herniated nucleus pulposus. We use the same technique to remove the lumbar chronic EDH, which is the first documented report in the related literature.

Methods:

We present a case with chronic lumbar EDH associated with spinal manipulation. Neurologic deficits were noted on physical examination. We arranged for a full-endoscopic interlaminar approach to remove the hematoma for the patient with the rigid endoscopy (Vertebris system; Richard Wolf, Knittlingen, Germany).

Results:

After surgery, the patient's radiculopathy immediately began to disappear. Magnetic resonance imaging (MRI) follow-up 10 days after the surgery revealed no residual hematoma. No complications were noted during the outpatient department follow up.

Conclusions:

Lumbar EDH is a possible complication of spinal manipulation. Patient experiencing rapidly progressive neurologic deficit require early surgical evacuation, while conservative treatment may only be applied to those with mild symptoms. A percutaneous full-endoscopic interlaminar approach may be a viable alternative for the treatment of those with chronic EDH with progressive neurologic deficits.

The past, present and future of minimally invasive spine surgery: a review and speculative outlook

In the last 25 years of spinal surgery, tremendous improvements have been made. The development of smart technologies with the overall aim of reducing surgical trauma has resulted in the concept of minimally invasive surgical techniques. Enhancements in microsurgery, endoscopy and various percutaneous techniques, as well as improvement of implant materials, have proven to be milestones. The advancement of training of spine surgeons and the integration of image guidance with precise intraoperative imaging, computer- and robot-assisted treatment modalities constitute the era of reducing treatment morbidity in spinal surgery. This progress has led to the present era of preserving spinal function. The promise of the continuing evolution of spinal surgery, the era of restoring spinal function, already appears on the horizon. The current state of minimally invasive spine surgery is the result of a long-lasting and consecutive development of smart technologies, along with stringent surgical training practices and the improvement of instruments and techniques. However, much effort in research and development is still mandatory to establish, maintain and evolve minimally invasive spine surgery. The education and training of the next generation of highly specialized spine surgeons is another key point. This paper will give an overview of surgical techniques and methods of the past 25 years, examine what is in place today, and suggest a projection for spine surgery in the coming 25 years by drawing a connection from the past to the future.

Minimally invasive lateral approach for adult degenerative scoliosis: lessons learned

OBJECT

Lateral minimally invasive thoracolumbar instrumentation techniques are playing an increasing role in the treatment of adult degenerative scoliosis. However, there is a paucity of data in determining the ideal candidate for a lateral versus a traditional approach, and versus a hybrid construct. The objective of this study is to present a method for utilizing the lateral minimally invasive surgery (MIS) approach for adult spinal deformity, provide clinical outcomes to validate our experience, and determine the limitations of lateral MIS for adult degenerative scoliosis correction.

METHODS

Radiographic and clinical data were collected for patients who underwent surgical correction of adult degenerative scoliosis between 2007 and 2012. Patients were retrospectively classified by degree of deformity based on coronal Cobb angle, central sacral vertical line (CSVL), pelvic incidence, lumbar lordosis (LL), sagittal vertical axis (SVA), pelvic tilt (PT), presence of comorbidities, bone quality, and curve flexibility. Patients were placed into 1 of 3 groups according to the severity of deformity: "green" (mild), "yellow" (moderate), and "red" (severe). Clinical outcomes were determined by a visual analog scale (VAS) and the Oswestry Disability Index (ODI).

RESULTS

Of 256 patients with adult degenerative scoliosis, 174 underwent a variant of the lateral approach. Of these 174 patients, 27 fit the strict inclusion/exclusion criteria (n = 9 in each of the 3 groups). Surgery in 17 patients was dictated by their category, and 10 were treated with surgery outside of their classification. The average age was 61 years old and the mean follow-up duration was 17 months. The green and yellow groups experienced a reduction in coronal Cobb angle (12° and 11°, respectively), and slight changes in CSVL, SVA, and PT, and LL. In the green group, the VAS and ODI improved by 35 and 17 points, respectively, while in the yellow group they improved by 36 and 33 points, respectively. The red subgroup showed a 22° decrease in coronal Cobb angle, 15° increase in LL, and slight changes in PT and SVA. Three patients placed in the yellow subgroup had "green" surgery, and experienced a coronal Cobb angle and LL decrease by 17° and 10°, respectively, and an SVA and PT increase by 1.3 cm and 5°, respectively. Seven patients placed in the red group who underwent "yellow" or "green" surgery had a reduction in coronal Cobb angle of 16°, CSVL of 0.1 cm, SVA of 2.8 cm, PT of 4°, VAS of 28 points, and ODI of 12 points; lumbar lordosis increased by 15°. Perioperative complications included 1 wound infection, transient postoperative thigh numbness in 2 cases, and transient groin pain in 1 patient.

CONCLUSIONS

Careful patient selection is important for the application of lateral minimally invasive techniques for adult degenerative scoliosis. Isolated lateral interbody fusion with or without instrumentation is suitable for patients with preserved spinopelvic harmony. Moderate sagittal deformity (compensated with pelvic retroversion) may be addressed with advanced derivatives of the lateral approach, such as releasing the anterior longitudinal ligament. For patients with severe deformity, the lateral approach may be used for anterior column support and to augment arthrodesis.

Minimally invasive transforaminal lumbar interbody fusion (MI-TLIF): surgical technique, long-term 4-year prospective outcomes, and complications compared with an open TLIF cohort

Transforaminal lumbar interbody fusion (TLIF) is an important surgical option for the treatment of back pain and radiculopathy. The minimally invasive TLIF (MI-TLIF) technique is increasingly used to achieve neural element decompression, restoration of segmental alignment and lordosis, and bony fusion. This article reviews the surgical technique, outcomes, and complications in a series of 144 consecutive 1- and 2-level MI-TLIFs in comparison with an institutional control group of 54 open traditional TLIF procedures with a mean of 46 months' follow-up. The evidence base suggests that MI-TLIF can be performed safely with excellent long-term outcomes.

Craniocervical junction diseases treatment with a minimally invasive approach

Objective: To introduce a new minimally invasive surgical approach to anterior and lateral craniocervical junction diseases, preserving the midline posterior cervical spine stabilizing elements and reducing the inherent morbidity risk associated with traditional approaches. Methods: We describe a novel surgical technique in four cases of extra-medullary anterolateral compressive lesions located in the occipito-cervical junction, including infections and intra- and/or extradural tumor lesions. We used a paramedian trasmuscular approach through an anatomical muscle corridor using a micro MaXcess(r) surgical expandable retractor, with the purpose of reducing morbidity and preserving the posterior muscle and ligamentous tension band. Results: This type of surgical approach provides adequate visualization and microsurgical resection of lesions and reduces muscle manipulation and devascularisation, preserving the tension of the ligament complex. There was minimal blood loss and a decrease in postoperative pain, with rapid start of rehabilitation and shorter hospitalization times. There were no intraoperative complications, and all patients recovered from their pre-operative symptoms. Conclusions: This novel surgical technique is feasible and adequate for the occipito-atlanto-axial complex, with better results than traditional procedures.

Minimally Invasive Posterior Trans-muscular C1-C2 Screw Fixation Through an Anatomical Corridor to Preserve Occipitocervical Tension Band: Surgical Anatomy and Clinical Experience

The C1-C2 joint is affected by multiple entities that may produce biomechanical instability. Optimal management for atlantoaxial instability has been searched by ways of different surgical techniques with different results, generating discussion between second effects of a particular treatment. Lateral dissections can place the axial neck musculature and ligaments at risk of neural denervations or vascular compromise. Either of these entities may result in significant postoperative atrophy, pain, and instability. Minimally invasive techniques for the treatment of spinal disorders allow to our patients less morbid procedures with equal or better results compared to conventional surgery. In the following paper, we review the anatomy of the atlantoaxial joint and propose a minimally invasive trans-muscular C1-C2 fusion technique using C1 lateral-mass screws and C2 pedicular screws. We describe cases with surgical, clinical, and radiographic follow-up.

Minimally invasive thoracic decompression for multi-level thoracic pathologies

We describe our experience using a minimal access approach for multi-level dorsal decompression of the thoracic spine that may limit approach-related soft-tissue injury and spinal destabilization. Additionally, three patients, each with unique compressive thoracic pathology, are discussed. A single minimal access technique, using multi-level hemilaminotomies, was used to address these unique pathologies via a similar approach. The three patients in this study had a mean age of 49.3 years (range: 45-55 years), mean estimated blood loss of 750 cc (range: 350-1000 cc), mean operative time of 3.8 hours (range: 3-5 hours), and a mean post-operative hospital stay of 2.3 days (range: 2-3 days). Complete decompression was achieved with resolution of symptoms in all patients. Long-term follow-up averaged 26.7 months (range: 15-36 months). Radiographic decompression was demonstrated in all patients. Minimal access techniques using muscle-splitting tubular retractor systems can effectively treat multi-level dorsal compression of the thoracic cord, while potentially limiting morbidity and long-term spinal instability.

Microendoscopic decompression for cervical spondylotic myelopathy

Object

Cervical spondylotic myelopathy (CSM) is a common cervical degenerative disease that affects the elderly population. Spinal cord decompression is achieved through various anterior and posterior approaches including anterior cervical decompression and fusion, laminectomy, laminoplasty, and combined approaches. The authors describe another option, minimally invasive endoscopically assisted decompression of stenosis (MEDS), which obviates the need for muscle dissection and disruption of the posterior tension band, a cause of postlaminectomy kyphosis.

Methods

The authors conducted a retrospective study of 10 patients with CSM who underwent MEDS from January 2002 through July 2012. Data were collected on demographics, preoperative and postoperative Nurick scores, postoperative Odom scores, and preoperative and postoperative Cobb angles.

Results

The mean patient age (± SD) was 67 ± 7.7 years; 8 patients were male. The average number of disc levels operated on was 2.2 (range 1–4). The mean Nurick score was 1.6 ± 0.7 preoperatively and improved to 0.3 ± 0.7 postoperatively (p < 0.0005). The postoperative Odom scores indicated excellent outcomes for 4 patients, good for 3, fair for 2, and poor for 1. The average preoperative focal Cobb angle at the disc levels operated on was −0.43º ± 1.9º. The average Cobb angle at the last follow-up visit was 0.25° ± 1.6° (p = 0.6). The average follow-up time was 18.9 ± 32.1 months. There were no intraoperative or postoperative complications.

Conclusions

For selected patients with CSM, whose pathologic changes are primarily posterior and who have acceptable preoperative lordosis, MEDS is an alternative to open laminectomy and laminoplasty.

The microendoscopic decompression of lumbar stenosis: a review of the current literature and clinical results

Lumbar stenosis is a well-defined pathologic condition with excellent surgical outcomes. Empiric evidence as well as randomized, prospective trials has demonstrated the superior efficacy of surgery compared to medical management for lumbar stenosis. Traditionally, lumbar stenosis is decompressed with open laminectomies. This involves removal of the spinous process, lamina, and the posterior musculoligamentous complex (posterior tension band). This approach provides excellent improvement in symptoms, but is also associated with potential postoperative spinal instability. This may result in subsequent need for spinal fusion. Advances in technology have enabled the application of minimally invasive spine surgery (MISS) as an acceptable alternative to open lumbar decompression. Recent studies have shown similar to improved perioperative outcomes when comparing MISS to open decompression for lumbar stenosis. A literature review of MISS for decompression of lumbar stenosis with tubular retractors was performed to evaluate the outcomes of this modern surgical technique. In addition, a discussion of the advantages and limitations of this technique is provided.

Paradigm changes in spine surgery: evolution of minimally invasive techniques

Minimally invasive spine surgery (MISS) techniques were developed to address morbidities associated with open spinal surgery approaches. MISS was initially applied for indications such as the microendoscopic decompression of stenosis (MEDS)-an operation that has become widely implemented in modern spine surgery practice. Minimally invasive surgery for MEDS is an excellent example of how an MISS technique has improved outcomes compared with the use of traditional open surgical procedures. In parallel with reports of surgeon experience, accumulating clinical evidence suggests that MISS is favoured over open surgery, and one could argue that the role of MISS techniques will continue to expand. As the field of minimally invasive surgery has developed, MISS has been implemented for the treatment of increasingly difficult and complex pathologies, including trauma, spinal malignancies and spinal deformity in adults. In this Review, we present the accumulating evidence in support of minimally invasive techniques for established MISS indications, such as lumbar stenosis, and discuss the need for additional level I and level II data to demonstrate the benefit of MISS over traditional open surgery. The expanding utility of MISS techniques to address an increasingly broad range of spinal pathologies is also highlighted.

Perioperative pain management in the neurosurgical patient

Perioperative pain management in neurosurgical patients has been inadequately recognized and treated. An increased awareness of pain management and advances in understanding of pain modulation and pathophysiology have led to improved perioperative care of patients. There is a need to assess neurologic function while providing superior analgesia with minimal side effects. Several classes of drugs are currently available or under investigation for use as adjuvants or alternative therapies. There remains a need to determine the best treatment of perioperative pain in this patient population. Improved awareness, assessment, and treatment of pain result in better care and overall patient outcome.

Minimally invasive lateral extracavitary corpectomy: cadaveric evaluation model and report of 3 clinical cases

OBJECT

In this paper, the authors' goal was to demonstrate the clinical and technical nuances of a minimally invasive lateral extracavitary approach (MI-LECA) for thoracic corpectomy and anterior column reconstruction.

METHODS

A cadaveric feasibility study and the subsequent application of this approach in 3 clinical cases are reported. Six procedures were completed in 3 human cadavers. Minimally invasive, extrapleural thoracic corpectomies were performed with the aid of a 24-mm tubular retraction system, using a posterolateral incision and an oblique approach angle. Fluoroscopy and postprocedural CT scanning, using 3D volumetric averaging software, was used to evaluate the degree of bone removal and decompression. Three clinical cases, including a T-11 burst fracture, a T-7 plasmacytoma, and a T4-5 vertebral body (VB) tuberculosis lesion, were treated using the approach.

RESULTS

At 6 cadaveric levels, the mean circumferential volumetric decompression was 48% ± 16%, and the mean resection of the VB was 72% ± 13%. The mean change in anterior and posterior vertebral height with expansion of the corpectomy cage was 47 and 61 mm, respectively. There were no violations of the pleura or dura. Pedicle screw reliability was 95.8% (23 of 24 screws) with a single lateral breach. All 3 patients in the clinical cohort had excellent clinical outcomes. There was a single pleural tear requiring chest tube drainage. Operative images and a video clip are provided to illustrate the approach.

CONCLUSIONS

A minimally invasive lateral extracavitary thoracic corpectomy has the ability to provided excellent spinal cord decompression and VB resection. The procedure can be completed safely and successfully with minimal blood loss and little associated morbidity. This approach has the potential to improve upon established traditional open corridors for posterolateral thoracic corpectomy.