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

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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.

ABBREVIATIONSIQR = interquartile range; MED = microendoscopic discectomy; MIS = minimally invasive surgical; PCS = prospective cohort study; PRISMA = Preferred Reporting Items for Systematic Reviews and Meta-Analyses; RCT = randomized controlled trial.

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.

While the traditional open microdiscectomy technique provides excellent outcomes, it carries the risk of complications such as postoperative CSF leak, nerve root injury, and postoperative pain.24,55,63,64 Because minimally invasive surgical (MIS) techniques, such as microendoscopic discectomy (MED) and percutaneous microdiscectomy, minimize the manipulation of surrounding tissue, they have been purported to decrease complication rates and reduce postoperative pain in addition to improving function.15,20 However, outcome studies have yet to verify the claims that MIS techniques for lumbar microdiscectomy are better than conventional methods.34 Complications related to lumbar microdiscectomy are typically analyzed from an institutional or individual surgeon perspective.4,5,31 A systematic review and meta-analysis of complications following the various surgical techniques to perform lumbar microdiscectomy has not been previously performed. Accurate knowledge of complication rates following conventional open, MED, and percutaneous approaches can be used to help educate patients and surgeons during the informed consent process. We sought to identify differences in complication rates among open, MED, and percutaneous microdiscectomy by performing a systematic review and meta-analysis of all complications reported in clinical studies.

Methods

Study Search

The systematic review was conducted following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA).39 We conducted MEDLINE, Scopus, Web of Science, and Embase database searches with the search algorithm: (“Lumbar Discectomy Complication(s)”) OR (“Lumbar Discectomy Complication(s) and Outcome(s)”) OR ((“Lumbar” and “Discectomy” or “Microdiscectomy”) AND (“Complications” or “Outcomes”)). The search returned 9504 citations. We searched for articles published between January 1, 1990, and December 27, 2014.

Inclusion and Exclusion Criteria

Articles published prior to 1990 were excluded to avoid a historical bias and because MIS techniques were not yet widely used.59 To create a more homogenous patient cohort, studies involving the following procedures were excluded: interbody fusion, transperitoneal lumbar microdiscectomy, corpectomy, revision surgery, and lumbar microdiscectomy spanning more than one vertebral level. We included studies in which lumbar microdiscectomy was performed for degenerative indications and excluded those in which lumbar discectomy was performed to treat infection and tumor pathological processes. We imposed no restrictions on publication status. Animal, in vitro, bio-mechanical, and non-English language studies were excluded. We also excluded those concerning large administrative data sets because different surgical techniques were not separated and many complications are frequently underreported in coded data. We included prospective cohort studies (PCSs) and randomized controlled trials (RCTs; experimental or control arms). We excluded all retrospective chart reviews since many complications are underreported in retrospective studies. For clinical studies using duplicate data, only the study with the most recent results was included.

Data Collection

Three reviewers (M.F.S., J.J.X., and E.Y.T.) independently conducted data extraction from the 42 included articles. The extracted data sets were compared to confirm accuracy. Level of evidence for each of the included articles was assessed using the Oxford Centre for Evidence Based Medicine Level of Evidence 2 classification system (http://www.cebm.net/ocebm-levels-of-evidence/). From the eligible articles, we recorded the publication year, follow-up period (months), number of patients, complications, and collection method. The included studies reported the following complications: nerve root injury, new or worsening neurological deficit, medical complications, surgical errors, durotomy, hematoma, wound complications, recurrent disc complications at the primary surgical site, and reoperation. Criteria and definitions for each complication are summarized in Table 1. Nerve root injuries were recorded separately from new or worsening neurological deficit because some studies reported intraoperative puncture, displacement, or direct injury to the nerve root but did not correlate it to postoperative neurological deficit development. Additionally, surgical errors consisted of exploration started at the wrong vertebral level and surgical instrument breakage during the operative procedure.

TABLE 1.

Criteria and definitions for complications reported among included studies

ComplicationCriteria
Nerve root injury*Defined as any intraop nerve root puncture or direct nerve root injury & nerve root displacement
New or worsening neurological deficitIncluded increased motor or sensory deficit or new postop radiculopathy
Medical complicationsIncluded deep vein thrombosis, pulmonary embolism, myocardial infarction, urinary tract infection, acute kidney or lung disorders, & respiratory distress or failure
Surgical errorsConsisted of exploration started at wrong vertebral level & surgical instrument breakage during the procedure
DurotomyRecorded for any incidental intraop injury to dura or postop CSF leak
HematomaIncluded wound & perineural hematoma
Wound complicationsIncluded cellulitis, discitis, spondylodiscitis, skin infection, superficial wound infection, suture granuloma, dehiscence, & seroma
Recurrent disc complicationsIncluded any persistent or relapsing disc herniation or prolapse
ReoperationIncluded any reop during the postop period, regardless of indication

Studies reporting intraoperative nerve root injury without subsequent correlation to postoperative neurological deficit.

Open lumbar microdiscectomy surgeries use a longitudinal midline incision over the area of the herniated disc and employ a microscope for visualization.2,3,9,17–19,21,25,26,28,33,36,41–43,45,49,52–54,56–58,61 MED techniques employ a longitudinal paramedian incision through which a tubular retractor is placed and visualization is achieved through an endoscope.2,6,10,13,19,24,25,29,36,46,51,53,57,60,62,64 Percutaneous discectomy entails placing a sheath directly into the disc space via a transforaminal approach, extraforaminal approach, or interlaminar approach and then using a suction/debrider or chemical injection to remove the disc.1,11,12,23,30,37,44,50

To assess the risk of bias for each study, 3 reviewers (M.F.S., J.J.X., and E.Y.T.) independently investigated the individual studies and used The Cochrane Collaboration’s tool for assessing risk of bias.22 Bias risk assessment was performed at the study level. Inconsistencies in bias risk assessment were reconciled through discussion.

Statistical Analysis

Unweighted overall mean complication rates were calculated by the summation of total complication events divided by the overall number of patients included in the studies reporting that specific complication. If a study reported zero events for a particular complication, the study’s cohort was included in the denominator. To assess the variation in the rate of a specific complication across studies, an interstudy median and interquartile range (IQR), which ranged from the first to the third quartile (Q1-Q3), were calculated to demonstrate variations in specific cross-study complication rates.

We also analyzed complication data using a randomeffects model with inverse variance weighting. Calculations for the meta-analysis and construction of forest plots were completed using an established spreadsheet by Neyeloff et al.40 The principal summary measures were the effect summary values and 95% CIs. The presence of zero complication events in some studies did not permit calculations. To allow for inclusion of these studies, we substituted a value of 0.1 complication events per study and calculations were performed using this value. Because of the lack of consistent control groups across all included studies, we were unable to calculate relative risk ratios. We compared results among studies with 95% CIs and forest plots.

To assess heterogeneity between individual studies, a Q statistic and I2 value were calculated within each complication’s meta-analysis. Delong et al.14 established an I2 less than 25% as low heterogeneity, 25%–75% as moderate heterogeneity, and greater than 75% as severe heterogeneity. These same values were used to assess heterogeneity in our meta-analysis.

Results

Study Selection

After removing 6870 duplicates, the titles and abstracts of 2634 publications were screened (Figs. 1 and 2, Table 2).39 The full text was assessed in the resulting 402 articles for eligibility criteria. Full-text assessment resulted in 42 eligible articles (0.4%) to be included in the final analysis. Twenty-four studies reported utilization of the open microdiscectomy technique, while 16 and 8 studies reported the use of MED and percutaneous approaches, respectively.

FIG. 1.
FIG. 1.

PRISMA flow diagram.

FIG. 2.
FIG. 2.

Included studies according to year of publication.

TABLE 2.

Included studies identified by systematic literature review

Authors & YearFollow-Up (mos)No. of PatientsType of OpCollection Method
Galarza et al., 20142447OpenP
Hussein et al., 201496Open: 90, MED: 95Open, MEDP, PR
Tsutsumimoto et al., 20146555MEDP
Choi et al., 20132489PercutaneousP, PR
Yoshimoto et al., 20131226MEDP, chart
Hirano et al., 2012337PercutaneousP
Kaushal et al., 201224300MEDP
Lønne et al., 20121291OpenPR, IO
Martín-Láez et al., 201224Open: 101, MED: 37Open, MEDP
Righesso et al., 201224149OpenP
Wang et al., 2012120151MEDP, PR
Casal-Moro et al., 201160120MEDPR, IO
Celik et al., 20118364OpenP, chart
Chen et al., 201112123MEDNot defined
Choi et al., 20112452PercutaneousPR
Chumnanvej et al., 20112360MEDP
Garg et al., 201112Open: 57, MED: 55Open, MEDIO
Aronsohn et al., 2010250PercutaneousNot defined
Kaner et al., 20104140OpenChart
Nicassio et al., 201030262OpenNot defined
Teli et al., 201029Open: 72, MED: 70Open, MEDChart
Arts et al., 200912Open: 159, MED: 166Open, MEDIO
Franke et al., 20091248OpenP, PR
Harrington et al., 2008335OpenResearch nurse, chart
Parikh et al., 20089141MEDP, PR, chart
Peul et al., 200824180OpenResearch nurse
Ruetten et al., 200824Open: 100, MED: 100Open, MEDPR, IO
Ryang et al., 20082630OpenPR, IO
Righesso et al., 20072421MEDNot defined
Ivanic et al., 2006631OpenIO, PR
Osterman et al., 20062428OpenPR
Tassi, 200636500OpenPR
Thomé et al., 20051842OpenPR
Türeyen, 20031263OpenPR
Aydin et al., 200232.4200OpenPR
Huang et al., 20011211MEDNot defined
Krugluger et al., 20002410PercutaneousNot defined
Nygaard et al., 20001239OpenIO
Nygaard et al., 19991298OpenIO
Mayer et al., 19934820PercutaneousIO
Revel et al., 1993669PercutaneousP, PR
Onik ét al., 199012506PercutaneousIO

IO = independent observer; P = physician; PR = patient-reported.

Bias risk assessment of the included studies identified a marked difference between RCTs and PCSs, with RCTs demonstrating significantly less bias among sequence generation, allocation concealment, and blinding of participants, personnel, and outcome assessors (Table 3).22 No studies demonstrated a high risk of incomplete outcome data or selective reporting of outcomes.22

TABLE 3.

Bias risk assessment for all 42 included studies identified by systematic review

Authors & YearStudy TypeSequence GenerationAllocation ConcealmentBlinding of Participants, Personnel, & Outcome AssessorsIncomplete Outcome DataSelect Outcome ReportingOther Sources of Bias
Galarza et al., 2014PCSLowUnclearLowLowLowLow
Hussein et al., 2014RCTLowLowUnclearLowLowLow
Tsutsumimoto et al., 2014PCSLowUnclearHighUnclearLowLow
Choi et al., 2013PCSLowUnclearLowLowLowLow
Yoshimoto et al., 2013PCSLowUnclearLowLowLowHigh
Hirano et al., 2012PCSLowUnclearUnclearLowHighHigh
Kaushal et al., 2012PCSLowUnclearLowLowLowHigh
Lønne et al., 2012PCSLowUnclearUnclearLowHighLow
Martín-Láez et al., 2012PCSLowLowHighLowLowLow
Righesso et al., 2012PCSLowLowUnclearLowLowLow
Wang et al., 2012PCSLowUnclearLowLowLowLow
Casal-Moro et al., 2011PCSLowLowHighLowLowHigh
Celik et al., 2011RCTLowUnclearLowLowLowLow
Chen et al., 2011PCSUnclearLowHighLowLowLow
Choi et al., 2011PCSLowUnclearUnclearLowLowUnclear
Chumnanvej et al., 2011PCSLowUnclearUnclearLowLowLow
Garg et al., 2011PCSLowLowLowLowLowLow
Aronsohn et al., 2010RCTLowLowLowLowLowLow
Kaner et al., 2010PCSLowLowUnclearLowLowLow
Nicassio et al., 2010PCSUnclearHighHighLowLowHigh
Teli et al., 2010RCTLowLowLowLowLowLow
Arts et al., 2009RCTLowLowLowLowLowLow
Franke et al., 2009RCTLowLowLowLowLowUnclear
Harrington et al., 2008PCSUnclearUnclearLowLowUnclearLow
Parikh et al., 2008PCSUnclearUnclearUnclearLowLowUnclear
Peul et al., 2008RCTLowLowLowLowLowLow
Ruetten et al., 2008RCTLowLowLowLowLowLow
Ryang et al., 2008RCTLowLowLowLowLowLow
Righesso et al., 2007RCTLowLowLowLowLowLow
Ivanic et al., 2006RCTLowUnclearLowLowLowLow
Osterman et al., 2006RCTLowUnclearLowLowLowLow
Tassi, 2006PCSLowUnclearHighLowLowLow
Thomé et al., 2005PCSLowLowUnclearLowLowLow
Türeyen, 2003PCSLowUnclearUnclearLowLowLow
Aydin et al., 2002PCSLowLowLowLowLowLow
Huang et al., 2001PCSLowUnclearLowLowLowLow
Krugluger et al., 2000RCTLowUnclearUnclearLowLowUnclear
Nygaard et al., 2000PCSLowUnclearHighLowLowLow
Nygaard et al., 1999PCSLowHighLowLowLowLow
Mayer et al., 1993RCTLowLowLowLowLowLow
Revel et al., 1993RCTLowLowLowLowLowLow
Onik et al., 1990PCSLowLowUnclearUnclearLowLow

Neurological Injuries

Intraoperative nerve root injury was identified by 19 studies (Table 4, Figs. 3 and 4). Studies performing open, MED, and percutaneous techniques resulted in unweighted means of 2.6% (median 0.0%), 0.9% (median 0.7%), and 1.1% (median 0.7%), respectively. Meta-analysis calculations revealed a statistically significant higher rate of intraoperative nerve root injury following percutaneous procedures relative to MED. A new or worsening neurological deficit was reported in 15 studies. Studies involving open microdiscectomy, MED, and percutaneous microdiscectomy resulted in unweighted means of 1.3% (median 1.2%), 3.0% (median 2.8%), and 1.6% (median 5.0%), respectively. Meta-analysis calculations indicated no statistically significant difference between the surgical techniques.

FIG. 3.
FIG. 3.

Combined bar graph for the overall rates of various complications across open, microendoscopic, and percutaneous lumbar microdiscectomy.

FIG. 4.
FIG. 4.

Meta-analysis effect summary values and 95% CIs for Identified complications following each surgical technique.

TABLE 4.

Complication rates for open, MED, and percutaneous microdiscectomy

Neurological InjuriesContributing StudiesNo. of PatientsOverall Rate*Interstudy Median Rate (IQR)
Nerve root injury
 Open76182.6%0.0% (0.0%–0.9%)
 MED1010650.9%0.7% (0.0%–1.6%)
 Percutaneous2891.1%0.7% (0.4%–1.1%)
New or worsening neurological deficit
 Open610691.3%1.2% (0.5%–1.7%)
 MED75733.0%2.8% (0.0%–3.1%)
 Percutaneous2621.6%5.0% (2.5%–7.5%)
General complications
Medical complications
 Open53842.6%2.6% (2.5%–3.6%)
 MED55872.6%0.0% (0.0%–0.8%)
 Percutaneous
Surgical errors
 Open11593.1%3.1%
 MED22861.0%1.0% (0.9%–1.1%)
 Percutaneous
Durotomy complications
Durotomy
 Open1414793.9%4.9% (1.5%–6.0%)
 MED1520194.5%4.8% (1.2%–7.4%)
 Percutaneous
Wound complications
Hematoma
 Open49300.5%0.6% (0.5%–0.7%)
 MED11661.2%1.2%
 Percutaneous47160.6%0.8% (0.1%–1.6%)
Wound complications
 Open1620162.1%2.2% (0.9%–3.4%)
 MED1313781.2%0.8% (0.0%–2.0%)
 Percutaneous46280.5%0.2% (0.0%–0.8%)
Recurrent complications
Recurrent disc complications
 Open1411924.4%4.8% (2.7%–6.1%)
 MED1215993.1%3.3% (1.8%–5.1%)
 Percutaneous31783.9%5.4% (3.8%–5.6%)
Reoperation
 Open1616317.1%7.1% (4.8%–10.1%)
 MED1417193.7%3.3% (2.1%–6.2%)
 Percutaneous671410.2%7.9% (5.5%–11.4%)

Overall rate = number of patients affected/total number of patients screened.

IQR = interquartile range from Quartile 1 to Quartile 3.

General Complications

Medical complications were reported in 10 studies but not in any studies performing percutaneous microdiscectomy (Table 4, Figs. 3 and 4). Open microdiscectomy and MED resulted in rates of medical complications of 2.6% (median 2.6%) and 2.6% (median 0.0%), respectively. Surgical errors were reported only in studies that involved open microdiscectomy and MED at rates of 3.1% (median 3.1%) and 1.0% (median 1.0%), respectively. No statistically significant differences were found among the different approaches.

Durotomy-Related Complications

Durotomy was identified in 29 studies (Table 4, Figs. 3 and 4). Open and MED techniques resulted in unweighted means of 3.9% (median 4.9%) and 4.5% (median 4.8%), respectively. Postoperative CSF leakage was reported by 1 study for open (1.3%) and MED (0.6%) approaches.2 Meta-analysis calculations, of durotomy rates, indicated no statistically significant difference among the surgical techniques.

Wound Complications

Nine total studies reported the development of a wound hematoma (Table 4, Figs. 3 and 4). Open, MED, and percutaneous microdiscectomy studies reported rates of 0.5% (median 0.6%), 1.2% (median 1.2%), and 0.6% (median 0.8%), respectively. Wound complications were identified in 33 studies. Open, MED, and percutaneous microdiscectomy techniques resulted in rates of 2.1% (median 2.2%), 1.2% (median 0.8%), and 0.5% (median 0.2%), respectively. There was no statically significant difference in reported hematoma or wound complication rates in the meta-analysis.

Recurrent Complications

Recurrent disc complications were reported by 29 studies and occurred in 4.4% (median 4.8%), 3.1% (median 3.3%), and 3.9% (median 5.4%) of patients undergoing open, MED, and percutaneous microdiscectomy, respectively (Table 4, Figs. 3 and 4). Reoperation occurred at rates of 7.1% (median 7.1%), 3.7% (median 3.3%), and 10.2% (median 7.9%) for open, MED, and percutaneous techniques, respectively. Meta-analysis calculations indicated no statistically significant difference between the surgical techniques.

Discussion

This study represents the most comprehensive systematic literature review and meta-analysis of complication rates associated with the various surgical techniques of lumbar microdiscectomy to date. While the 42 included studies represent a small sample of the 2634 total studies screened during our systematic review, we solely evaluated prospective studies because of bias and underreported complication rates outlined in retrospective studies. We analyzed reported complication rates and elucidated differences among open, MED, and percutaneous microdiscectomy procedures.

Open Microdiscectomy and MED

In our review and meta-analysis, we identified a number of complications following conventional open microdiscectomy and MED. While there were differences in unweighted mean complication rates following both surgical techniques, none reached statistical significance (Fig. 4). The conventional open procedure potentially requires more extensive muscle and soft-tissue dissection, and with its reliance on a microscope, it offers a restricted view during the operation.51 MED, on the other hand, achieves resection of the herniated disc by access through a smaller incision and uses a tubular retractor and endoscope.51 Prior studies evaluating MED have reported a reduction in postoperative complications.16,35,38,51 Authors performing the MED technique have purported better visualization with the endoscope, facilitating enhanced identification and manipulation of anatomical structures such as the nerve root and dural sac.7,8,51 These conclusions suggest that fewer complications should be observed when using MED relative to the conventional open technique. This, however, was not the case in our review. While the MED approach is less invasive for disc resection, we found no significant difference in complication rates compared with open microdiscectomy. We did not evaluate rates of improved neurological outcomes following these procedures because the literature was inconsistent in its reporting. Garg et al.19 have reported that MED results in less para-vertebral muscle trauma, fibrosis, and morbidity, along with reduced hospital length of stay, ultimately increasing overall patient satisfaction. Therefore, while MED is indeed associated with a learning curve during initial implementation, the lack of significant differences in complication rates advocates for MED as a potential alternative to traditional open microdiscectomy.

Open Microdiscectomy and Percutaneous Discectomy

While there were differences in complication rates between open and percutaneous microdiscectomy techniques, none reached statistical significance (Fig. 4). An advantage associated with percutaneous discectomy, over that seen with open conventional discectomy, is the elimination of the need for facet resection because the disc interspace is accessed through the triangle of Kambin, which decreases the risk for spine destabilization.27,48 In addition, a percutaneous approach requires less damage to muscular and ligamentous structures than open microdiscectomy. However, the evaluation of complication rates showed no statistical significance in our meta-analysis. Nonetheless, it is worth noting that there were fewer contributing studies for percutaneous discectomy than for MED and open microdiscectomy. The lack of significant difference in complication rates and advantages in terms of shorter operating time, shorter hospital stay, and disc height preservation suggests that percutaneous discectomy is a potential alternative for minimally invasive surgery.32,47 Further prospective or randomized controlled studies are required to more objectively evaluate the outcomes of the 2 techniques.

Limitations

Most abstracts and studies screened for complication rates in this review were retrospective case series, which limited the number of included studies. As a result, a small number of studies were analyzed, which somewhat restricted our ability to compare surgical techniques. Because of this limitation and concomitant lack of studies with direct comparisons or a consistent control group, we were unable to calculate relative risk values among the procedures. In addition, while stratification of complication rates by age and anatomical levels would decrease heterogeneity and reveal inherent differences associated with these factors, the primary literature is varied and does not routinely discuss these factors in reporting complications. Finally, this meta-analysis solely investigated complications associated with single-level lumbar microdiscectomy. Further research should be performed to explore complication rates across all forms of lumbar surgery, allowing for comparative effectiveness investigation.

Conclusions

This work presents a systematic review of complications reported in 42 studies published between 1990 and 2014, comparing the differences in complication rates among open microdiscectomy, MED, and percutaneous discectomy. Previous clinical studies have purported reduced complications when utilizing MIS techniques, but our analysis of complication rates following open microdiscectomy and MED showed no statistically significant differences. Furthermore, differences in complication rates between open microdiscectomy and percutaneous discectomy were not statistically significant. The resultant list of complications should serve as a framework to provide an educated and reasonably comprehensive informed consent discussion between the surgeon and the patient regarding potential expectations as well as alternative surgical techniques.

Author Contributions

Conception and design: Shriver, Xie, Rosenbaum, Kshettry. Acquisition of data: Shriver, Xie, Tye. Analysis and interpretation of data: Shriver, Xie, Tye. Drafting the article: Shriver, Xie, Critically revising the article: Shriver, Xie, Rosenbaum, Kshettry, Benzel, Mroz. Reviewed submitted version of manuscript: all authors. Approved the final version of the manuscript on behalf of all authors: Shriver. Statistical analysis: Xie, Tye.

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    Franke JGreiner-Perth RBoehm HMahlfeld KGrasshoff HAllam Y: Comparison of a minimally invasive procedure versus standard microscopic discotomy: a prospective randomised controlled clinical trial. Eur Spine J 18:99210002009

  • 18

    Galarza MGazzeri RDe la Rosa PMartínez-Lage JF: Microdiscectomy with and without insertion of interspinous device for herniated disc at the L5-S1 level. J Clin Neurosci 21:193419392014

  • 19

    Garg BNagraja UBJayaswal A: Microendoscopic versus open discectomy for lumbar disc herniation: a prospective randomised study. J Orthop Surg (Hong Kong) 19:30342011

  • 20

    Guyer RDFoley KTPhillips FMBall PA: Minimally invasive fusion: summary statement. Spine (Phila Pa 1976) 28:15 SupplS442003

  • 21

    Harrington JFFrench P: Open versus minimally invasive lumbar microdiscectomy: comparison of operative times, length of hospital stay, narcotic use and complications. Minim Invasive Neurosurg 51:30352008

  • 22

    Higgins JPTGreen S: Cochrane Handbook for Systematic Reviews of Interventions Version 5.1.0 LondonThe Cochrane Collaboration2011. (http://handbook.cochrane.org)Accessed August 5 2015

  • 23

    Hirano YMizuno JTakeda MItoh YMatsuoka HWatanabe K: Percutaneous endoscopic lumbar discectomy-early clinical experience. Neurol Med Chir (Tokyo) 52:6256302012

  • 24

    Huang TJHsu RWLee YYChen SH: Video-assisted endoscopic lumbar discectomy. Surg Endosc 15:117511782001

  • 25

    Hussein MAbdeldayem AMattar MM: Surgical technique and effectiveness of microendoscopic discectomy for large uncontained lumbar disc herniations: a prospective, randomized, controlled study with 8 years of follow-up. Eur Spine J 23:199219992014

  • 26

    Ivanic GMPink PTSchneider FStuecker MHomann NCPreidler KW: Prevention of epidural scarring after microdiscectomy: a randomized clinical trial comparing gel and expanded polytetrafluoroethylene membrane. Eur Spine J 15:136013662006

  • 27

    Kambin PBrager MD: Percutaneous posterolateral discectomy. Anatomy and mechanism. Clin Orthop Relat Res 2231451541987

  • 28

    Kaner TSasani MOktenoglu TAydin ALOzer AF: Minimum two-year follow-up of cases with recurrent disc herniation treated with microdiscectomy and posterior dynamic transpedicular stabilisation. Open Orthop J 4:1201252010

  • 29

    Kaushal MSen R: Posterior endoscopic discectomy: Results in 300 patients. Indian J Orthop 46:81852012

  • 30

    Krugluger JKnahr K: Chemonucleolysis and automated percutaneous discectomy—a prospective randomized comparison. Int Orthop 24:1671692000

  • 31

    Lau DHan SJLee JGLu DCChou D: Minimally invasive compared to open microdiscectomy for lumbar disc herniation. J Clin Neurosci 18:81842011

  • 32

    Lee DYShim CSAhn YChoi YGKim HJLee SH: Comparison of percutaneous endoscopic lumbar discectomy and open lumbar microdiscectomy for recurrent disc herniation. J Korean Neurosurg Soc 46:5155212009

  • 33

    Lønne GSolberg TKSjaavik KNygaard OP: Recovery of muscle strength after microdiscectomy for lumbar disc herniation: a prospective cohort study with 1-year follow-up. Eur Spine J 21:6556592012

  • 34

    Lubelski DMihalovich KESkelly ACFehlings MGHarrop JSMummaneni PV: Is minimal access spine surgery more cost-effective than conventional spine surgery?. Spine (Phila Pa 1976) 39:22 Suppl 1S65S742014

  • 35

    Maroon JC: Current concepts in minimally invasive discectomy. Neurosurgery 51:5 SupplS137S1452002

  • 36

    Martín-Láez RMartínez-Agüeros JASuárez-Fernández DMontiaga-Núñez FVázquez-Barquero A: Complications of endoscopic microdiscectomy using the EASYGO! system: is there any difference with conventional discectomy during the learning-curve period?. Acta Neurochir (Wien) 154:102310322012

  • 37

    Mayer HMBrock M: Percutaneous endoscopic discectomy: surgical technique and preliminary results compared to microsurgical discectomy. J Neurosurg 78:2162251993

  • 38

    Mixter WJBarr JS: Rupture of the intervertebral disc with involvement of the spinal canal. N Engl J Med 211:2102151934

  • 39

    Moher DLiberati ATetzlaff JAltman DG: Preferred reporting items for systematic reviews and meta-analyses: the PRISMA statement. BMJ 339:b25352009

  • 40

    Neyeloff JLFuchs SCMoreira LB: Meta-analyses and Forest plots using a Microsoft Excel spreadsheet: step-by-step guide focusing on descriptive data analysis. BMC Res Notes 5:522012

  • 41

    Nicassio NBobicchio PUmari MTacconi L: Lumbar microdiscectomy under epidural anaesthesia with the patient in the sitting position: a prospective study. J Clin Neurosci 17:153715402010

  • 42

    Nygaard OPJacobsen EASolberg TKloster RDullerud R: Postoperative nerve root displacement and scar tissue. A prospective cohort study with contrast-enhanced MR imaging one year after microdiscectomy. Acta Radiol 40:5986021999

  • 43

    Nygaard OPKloster RSolberg TMellgren SI: Recovery of function in adjacent nerve roots after surgery for lumbar disc herniation: use of quantitative sensory testing in the exploration of different populations of nerve fibers. J Spinal Disord 13:4274312000

  • 44

    Onik GMooney VMaroon JCWiltse LHelms CSchweigel J: Automated percutaneous discectomy: a prospective multi-institutional study. Neurosurgery 26:2282331990

  • 45

    Osterman HSeitsalo SKarppinen JMalmivaara A: Effectiveness of microdiscectomy for lumbar disc herniation: a randomized controlled trial with 2 years of follow-up. Spine (Phila Pa 1976) 31:240924142006

  • 46

    Parikh KTomasino AKnopman JBoockvar JHärtl R: Operative results and learning curve: microscope-assisted tubular microsurgery for 1- and 2-level discectomies and laminectomies. Neurosurg Focus 25:2E142008

  • 47

    Peng CWYeo WTan SB: Percutaneous endoscopic discectomy: clinical results and how it affects the quality of life. J Spinal Disord Tech 23:4254302010

  • 48

    Peng CWYeo WTan SB: Percutaneous endoscopic lumbar discectomy: clinical and quality of life outcomes with a minimum 2 year follow-up. J Orthop Surg 4:202009

  • 49

    Peul WCvan den Hout WBBrand RThomeer RTKoes BW: Prolonged conservative care versus early surgery in patients with sciatica caused by lumbar disc herniation: two year results of a randomised controlled trial. BMJ 336:135513582008

  • 50

    Revel MPayan CVallee CLaredo JDLassale BRoux C: Automated percutaneous lumbar discectomy versus chemonucleolysis in the treatment of sciatica. A randomized multicenter trial. Spine (Phila Pa 1976) 18:171993

  • 51

    Righesso OFalavigna AAvanzi O: Comparison of open discectomy with microendoscopic discectomy in lumbar disc herniations: results of a randomized controlled trial. Neurosurgery 61:5455492007

  • 52

    Righesso OFalavigna AAvanzi O: Correlation between persistent neurological impairment and clinical outcome after microdiscectomy for treatment of lumbar disc herniation. Neurosurgery 70:3903972012

  • 53

    Ruetten SKomp MMerk HGodolias G: Full-endoscopic interlaminar and transforaminal lumbar discectomy versus conventional microsurgical technique: a prospective, randomized, controlled study. Spine (Phila Pa 1976) 33:9319392008

  • 54

    Ryang YMOertel MFMayfrank LGilsbach JMRohde V: Standard open microdiscectomy versus minimal access trocar microdiscectomy: results of a prospective randomized study. Neurosurgery 62:1741822008

  • 55

    Sihvonen THerno APaljärvi LAiraksinen OPartanen JTapaninaho A: Local denervation atrophy of paraspinal muscles in postoperative failed back syndrome. Spine (Phila Pa 1976) 18:5755811993

  • 56

    Tassi GP: Comparison of results of 500 microdiscectomies and 500 percutaneous laser disc decompression procedures for lumbar disc herniation. Photomed Laser Surg 24:6946972006

  • 57

    Teli MLovi ABrayda-Bruno MZagra ACorriero AGiudici F: Higher risk of dural tears and recurrent herniation with lumbar microendoscopic discectomy. Eur Spine J 19:4434502010

  • 58

    Thomé CBarth MScharf JSchmiedek P: Outcome after lumbar sequestrectomy compared with microdiscectomy: a prospective randomized study. J Neurosurg Spine 2:2712782005

  • 59

    Thongtrangan ILe HPark JKim DH: Minimally invasive spinal surgery: a historical perspective. Neurosurg Focus 16:1E132004

  • 60

    Tsutsumimoto TYui MUehara MOhta HKosaku HMisawa H: A prospective study of the incidence and outcomes of incidental dural tears in microendoscopic lumbar decompressive surgery. Bone Joint J 96-B:6416452014

  • 61

    Türeyen K: One-level one-sided lumbar disc surgery with and without microscopic assistance: 1-year outcome in 114 consecutive patients. J Neurosurg 99:3 Suppl2472502003

  • 62

    Wang MZhou YWang JZhang ZLi C: A 10-year follow-up study on long-term clinical outcomes of lumbar microendoscopic discectomy. J Neurol Surg A Cent Eur Neurosurg 73:1951982012

  • 63

    Weinstein JNLurie JDTosteson TDTosteson ANBlood EAAbdu WA: Surgical versus nonoperative treatment for lumbar disc herniation: four-year results for the Spine Patient Outcomes Research Trial (SPORT). Spine (Phila Pa 1976) 33:278928002008

  • 64

    Yoshimoto MTakebayashi TIda KTanimoto KYamashita T: Microendoscopic discectomy in athletes. J Orthop Sci 18:9029082013

If the inline PDF is not rendering correctly, you can download the PDF file here.

Article Information

Correspondence Michael F. Shriver, Case Western Reserve University School of Medicine, 2109 Adelbert Rd., Cleveland, OH 44106. email: mfs82@case.edu.

INCLUDE WHEN CITING DOI: 10.3171/2015.7.FOCUS15281.

Disclosure Dr. Benzel has an ownership interest (stock options) in Axiomed, DePuy, Orthomens, and Turning Point. He also has grants from OREF and Rawlings. He receives royalties from Elsevier and Thieme as well. Dr. Mroz has received personal fees from Globus, AOSpine, and CeramTec and has an ownership interest (stock options) in PearlDriver, Inc. He has also received faculty honoraria from AOSpine.

© AANS, except where prohibited by US copyright law.

Headings

Figures

  • View in gallery

    PRISMA flow diagram.

  • View in gallery

    Included studies according to year of publication.

  • View in gallery

    Combined bar graph for the overall rates of various complications across open, microendoscopic, and percutaneous lumbar microdiscectomy.

  • View in gallery

    Meta-analysis effect summary values and 95% CIs for Identified complications following each surgical technique.

References

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    Aronsohn JChapman KSoliman MShah TCostandi SMichael R: Percutaneous microdiscectomy versus epidural injection for management of chronic spinal pain. Proc West Pharmacol Soc 53:16192010

  • 2

    Arts MPBrand Rvan den Akker MEKoes BWBartels RHPeul WC: Tubular diskectomy vs conventional microdiskectomy for sciatica: a randomized controlled trial. JAMA 302:1491582009

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    Aydin YZiyal IMDuman HTürkmen CSBaşak MSahin Y: Clinical and radiological results of lumbar microdiskectomy technique with preserving of ligamentum flavum comparing to the standard microdiskectomy technique. Surg Neurol 57:5142002

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    Cahill KSDunn IGunnarsson TProctor MR: Lumbar microdiscectomy in pediatric patients: a large single-institution series. J Neurosurg Spine 12:1651702010

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    Cahill KSLevi ADCummock MDLiao WWang MY: A comparison of acute hospital charges after tubular versus open microdiskectomy. World Neurosurg 80:2082122013

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    Casal-Moro RCastro-Menéndez MHernández-Blanco MBravo-Ricoy JAJorge-Barreiro FJ: Long-term outcome after microendoscopic diskectomy for lumbar disk herniation: a prospective clinical study with a 5-year follow-up. Neurosurgery 68:156815752011

  • 7

    Caspar W: A new surgical procedure for lumbar disc herniation causing less tissue damage through a microsurgical approach. Adv Neurosurg 4:74801977

  • 8

    Caspar WCampbell BBarbier DDKretschmmer RGotfried Y: The Caspar microsurgical discectomy and comparison with a conventional standard lumbar disc procedure. Neurosurgery 28:78871991

  • 9

    Çelik SGöksu KÇelik SEEmir CB: Benign neurological recovery with low recurrence and low peridural fibrosis rate in pediatric disc herniations after lumbar microdiscectomy. Pediatr Neurosurg 47:4174222011

  • 10

    Chen HTTsai CHChao SCKao THChen YJHsu HC: Endoscopic discectomy of L5–S1 disc herniation via an interlaminar approach: Prospective controlled study under local and general anesthesia. Surg Neurol Int 2:932011

  • 11

    Choi GModi HNPrada NAhn TJMyung SHGang MS: Clinical results of XMR-assisted percutaneous transforaminal endoscopic lumbar discectomy. J Orthop Surg 8:142013

  • 12

    Choi KCKim JSKang BULee CDLee SH: Changes in back pain after percutaneous endoscopic lumbar discectomy and annuloplasty for lumbar disc herniation: a prospective study. Pain Med 12:161516212011

  • 13

    Chumnanvej SKesornsak WSarnvivad PPaiboonsirijit SKuansongthum V: Full endoscopic lumbar discectomy via interlaminar approach: 2-year results in Ramathibodi Hospital. J Med Assoc Thai 94:146514702011. (Erratum in J Med Assoc Thai 95:296 2011)

  • 14

    DeLong WBPolissar NNeradilek B: Timing of surgery in cauda equina syndrome with urinary retention: meta-analysis of observational studies. J Neurosurg Spine 8:3053202008

  • 15

    Fessler RGO’Toole JEEichholz KMPerez-Cruet MJ: The development of minimally invasive spine surgery. Neurosurg Clin N Am 17:4014092006

  • 16

    Foley KTSmith MM: Microendoscopic discectomy. Tech Neurosurg 3:3013071997

  • 17

    Franke JGreiner-Perth RBoehm HMahlfeld KGrasshoff HAllam Y: Comparison of a minimally invasive procedure versus standard microscopic discotomy: a prospective randomised controlled clinical trial. Eur Spine J 18:99210002009

  • 18

    Galarza MGazzeri RDe la Rosa PMartínez-Lage JF: Microdiscectomy with and without insertion of interspinous device for herniated disc at the L5-S1 level. J Clin Neurosci 21:193419392014

  • 19

    Garg BNagraja UBJayaswal A: Microendoscopic versus open discectomy for lumbar disc herniation: a prospective randomised study. J Orthop Surg (Hong Kong) 19:30342011

  • 20

    Guyer RDFoley KTPhillips FMBall PA: Minimally invasive fusion: summary statement. Spine (Phila Pa 1976) 28:15 SupplS442003

  • 21

    Harrington JFFrench P: Open versus minimally invasive lumbar microdiscectomy: comparison of operative times, length of hospital stay, narcotic use and complications. Minim Invasive Neurosurg 51:30352008

  • 22

    Higgins JPTGreen S: Cochrane Handbook for Systematic Reviews of Interventions Version 5.1.0 LondonThe Cochrane Collaboration2011. (http://handbook.cochrane.org)Accessed August 5 2015

  • 23

    Hirano YMizuno JTakeda MItoh YMatsuoka HWatanabe K: Percutaneous endoscopic lumbar discectomy-early clinical experience. Neurol Med Chir (Tokyo) 52:6256302012

  • 24

    Huang TJHsu RWLee YYChen SH: Video-assisted endoscopic lumbar discectomy. Surg Endosc 15:117511782001

  • 25

    Hussein MAbdeldayem AMattar MM: Surgical technique and effectiveness of microendoscopic discectomy for large uncontained lumbar disc herniations: a prospective, randomized, controlled study with 8 years of follow-up. Eur Spine J 23:199219992014

  • 26

    Ivanic GMPink PTSchneider FStuecker MHomann NCPreidler KW: Prevention of epidural scarring after microdiscectomy: a randomized clinical trial comparing gel and expanded polytetrafluoroethylene membrane. Eur Spine J 15:136013662006

  • 27

    Kambin PBrager MD: Percutaneous posterolateral discectomy. Anatomy and mechanism. Clin Orthop Relat Res 2231451541987

  • 28

    Kaner TSasani MOktenoglu TAydin ALOzer AF: Minimum two-year follow-up of cases with recurrent disc herniation treated with microdiscectomy and posterior dynamic transpedicular stabilisation. Open Orthop J 4:1201252010

  • 29

    Kaushal MSen R: Posterior endoscopic discectomy: Results in 300 patients. Indian J Orthop 46:81852012

  • 30

    Krugluger JKnahr K: Chemonucleolysis and automated percutaneous discectomy—a prospective randomized comparison. Int Orthop 24:1671692000

  • 31

    Lau DHan SJLee JGLu DCChou D: Minimally invasive compared to open microdiscectomy for lumbar disc herniation. J Clin Neurosci 18:81842011

  • 32

    Lee DYShim CSAhn YChoi YGKim HJLee SH: Comparison of percutaneous endoscopic lumbar discectomy and open lumbar microdiscectomy for recurrent disc herniation. J Korean Neurosurg Soc 46:5155212009

  • 33

    Lønne GSolberg TKSjaavik KNygaard OP: Recovery of muscle strength after microdiscectomy for lumbar disc herniation: a prospective cohort study with 1-year follow-up. Eur Spine J 21:6556592012

  • 34

    Lubelski DMihalovich KESkelly ACFehlings MGHarrop JSMummaneni PV: Is minimal access spine surgery more cost-effective than conventional spine surgery?. Spine (Phila Pa 1976) 39:22 Suppl 1S65S742014

  • 35

    Maroon JC: Current concepts in minimally invasive discectomy. Neurosurgery 51:5 SupplS137S1452002

  • 36

    Martín-Láez RMartínez-Agüeros JASuárez-Fernández DMontiaga-Núñez FVázquez-Barquero A: Complications of endoscopic microdiscectomy using the EASYGO! system: is there any difference with conventional discectomy during the learning-curve period?. Acta Neurochir (Wien) 154:102310322012

  • 37

    Mayer HMBrock M: Percutaneous endoscopic discectomy: surgical technique and preliminary results compared to microsurgical discectomy. J Neurosurg 78:2162251993

  • 38

    Mixter WJBarr JS: Rupture of the intervertebral disc with involvement of the spinal canal. N Engl J Med 211:2102151934

  • 39

    Moher DLiberati ATetzlaff JAltman DG: Preferred reporting items for systematic reviews and meta-analyses: the PRISMA statement. BMJ 339:b25352009

  • 40

    Neyeloff JLFuchs SCMoreira LB: Meta-analyses and Forest plots using a Microsoft Excel spreadsheet: step-by-step guide focusing on descriptive data analysis. BMC Res Notes 5:522012

  • 41

    Nicassio NBobicchio PUmari MTacconi L: Lumbar microdiscectomy under epidural anaesthesia with the patient in the sitting position: a prospective study. J Clin Neurosci 17:153715402010

  • 42

    Nygaard OPJacobsen EASolberg TKloster RDullerud R: Postoperative nerve root displacement and scar tissue. A prospective cohort study with contrast-enhanced MR imaging one year after microdiscectomy. Acta Radiol 40:5986021999

  • 43

    Nygaard OPKloster RSolberg TMellgren SI: Recovery of function in adjacent nerve roots after surgery for lumbar disc herniation: use of quantitative sensory testing in the exploration of different populations of nerve fibers. J Spinal Disord 13:4274312000

  • 44

    Onik GMooney VMaroon JCWiltse LHelms CSchweigel J: Automated percutaneous discectomy: a prospective multi-institutional study. Neurosurgery 26:2282331990

  • 45

    Osterman HSeitsalo SKarppinen JMalmivaara A: Effectiveness of microdiscectomy for lumbar disc herniation: a randomized controlled trial with 2 years of follow-up. Spine (Phila Pa 1976) 31:240924142006

  • 46

    Parikh KTomasino AKnopman JBoockvar JHärtl R: Operative results and learning curve: microscope-assisted tubular microsurgery for 1- and 2-level discectomies and laminectomies. Neurosurg Focus 25:2E142008

  • 47

    Peng CWYeo WTan SB: Percutaneous endoscopic discectomy: clinical results and how it affects the quality of life. J Spinal Disord Tech 23:4254302010

  • 48

    Peng CWYeo WTan SB: Percutaneous endoscopic lumbar discectomy: clinical and quality of life outcomes with a minimum 2 year follow-up. J Orthop Surg 4:202009

  • 49

    Peul WCvan den Hout WBBrand RThomeer RTKoes BW: Prolonged conservative care versus early surgery in patients with sciatica caused by lumbar disc herniation: two year results of a randomised controlled trial. BMJ 336:135513582008

  • 50

    Revel MPayan CVallee CLaredo JDLassale BRoux C: Automated percutaneous lumbar discectomy versus chemonucleolysis in the treatment of sciatica. A randomized multicenter trial. Spine (Phila Pa 1976) 18:171993

  • 51

    Righesso OFalavigna AAvanzi O: Comparison of open discectomy with microendoscopic discectomy in lumbar disc herniations: results of a randomized controlled trial. Neurosurgery 61:5455492007

  • 52

    Righesso OFalavigna AAvanzi O: Correlation between persistent neurological impairment and clinical outcome after microdiscectomy for treatment of lumbar disc herniation. Neurosurgery 70:3903972012

  • 53

    Ruetten SKomp MMerk HGodolias G: Full-endoscopic interlaminar and transforaminal lumbar discectomy versus conventional microsurgical technique: a prospective, randomized, controlled study. Spine (Phila Pa 1976) 33:9319392008

  • 54

    Ryang YMOertel MFMayfrank LGilsbach JMRohde V: Standard open microdiscectomy versus minimal access trocar microdiscectomy: results of a prospective randomized study. Neurosurgery 62:1741822008

  • 55

    Sihvonen THerno APaljärvi LAiraksinen OPartanen JTapaninaho A: Local denervation atrophy of paraspinal muscles in postoperative failed back syndrome. Spine (Phila Pa 1976) 18:5755811993

  • 56

    Tassi GP: Comparison of results of 500 microdiscectomies and 500 percutaneous laser disc decompression procedures for lumbar disc herniation. Photomed Laser Surg 24:6946972006

  • 57

    Teli MLovi ABrayda-Bruno MZagra ACorriero AGiudici F: Higher risk of dural tears and recurrent herniation with lumbar microendoscopic discectomy. Eur Spine J 19:4434502010

  • 58

    Thomé CBarth MScharf JSchmiedek P: Outcome after lumbar sequestrectomy compared with microdiscectomy: a prospective randomized study. J Neurosurg Spine 2:2712782005

  • 59

    Thongtrangan ILe HPark JKim DH: Minimally invasive spinal surgery: a historical perspective. Neurosurg Focus 16:1E132004

  • 60

    Tsutsumimoto TYui MUehara MOhta HKosaku HMisawa H: A prospective study of the incidence and outcomes of incidental dural tears in microendoscopic lumbar decompressive surgery. Bone Joint J 96-B:6416452014

  • 61

    Türeyen K: One-level one-sided lumbar disc surgery with and without microscopic assistance: 1-year outcome in 114 consecutive patients. J Neurosurg 99:3 Suppl2472502003

  • 62

    Wang MZhou YWang JZhang ZLi C: A 10-year follow-up study on long-term clinical outcomes of lumbar microendoscopic discectomy. J Neurol Surg A Cent Eur Neurosurg 73:1951982012

  • 63

    Weinstein JNLurie JDTosteson TDTosteson ANBlood EAAbdu WA: Surgical versus nonoperative treatment for lumbar disc herniation: four-year results for the Spine Patient Outcomes Research Trial (SPORT). Spine (Phila Pa 1976) 33:278928002008

  • 64

    Yoshimoto MTakebayashi TIda KTanimoto KYamashita T: Microendoscopic discectomy in athletes. J Orthop Sci 18:9029082013

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