Surgical Complications of Microendoscopic Procedures for Lumbar Spinal Stenosis

Treatment Concept and Technical Considerations of Biportal Endoscopic Spine Surgery for Lumbar Spinal Stenosis

Decompression is a major component of surgical procedures for degenerative lumbar spinal stenosis (LSS). In addition to sufficient decompression to guarantee the relief of neurological pain, compensating surgical instability after wider laminectomy and foraminotomy and instrumentation with caging and fusion with grafting are performed to secure or restore the foraminal dimension and correct coronal/sagittal imbalance for longer survival of the adjacent segment. Endoscopic spinal surgery (ESS) has been developed under the flag of successful decompression while preserving structural integrity as much as possible with the help of magnification and illumination. ESS provides a technical possibility and feasibility for solving LSS by decompression alone. Recently, many endoscopic trials have been conducted to overcome conventional surgical treatment that requires wider dissection, escape inevitable complications from surgical damage, and compensate for the fusion technique. However, biportal ESS has some technical limitations, including clinical difficulties in accessibility for more moderate to severe stenosis and challenges for complicated conditions with segmental ventral slip, isthmic defect, stenosis combined with foraminal stenosis or foraminal disk rupture, or degenerative segmental scoliosis with disk height collapsing and endplate fatigue fracture. Because decompression alone is a skill for eliminating pathologies, there is no function of preserving degenerative structure or stopping the recurrence of disk degeneration or subsidence. This review of clinical reports investigated the possibility of biportal ESS for treating degenerative lumbar disorders by sufficient decompression and adequate elimination of various pathologies and decreasing technical complications. The results of this study may help develop better innovative spinal surgical techniques in the near future.

Is Minimally Invasive Spinal Surgery Superior to Endoscopic Spine Surgery in Postoperative Radiologic Outcomes of Lumbar Spine Degenerative Disease? A Systematic Review

BACKGROUND

 Minimally invasive spinal surgery (ESS) are both well-established surgical techniques for lumbar spinal stenosis; however, there is limited literature comparing the efficacy of the two techniques with respect to radiologic decompression data.

METHODS

 In this review, PubMed, Google Scholar, and Scopus databases were systematically searched from inception until July 2022 for studies that reported the radiologic outcomes of endoscopic and minimally invasive approaches for decompressive spinal surgery, namely, the spinal canal area, neural foraminal area, and neural foraminal heights.

RESULTS

 Of the 378 articles initially retrieved using MeSH and keyword search, 9 studies reporting preoperative and postoperative spinal areas and foraminal areas and heights were finally included in our review. Of the total 581 patients, 391 (67.30%) underwent MISS and 190 (32.70%) underwent ESS. The weighted mean difference between the spinal canal diameter in pre- and postoperative conditions was 56.64 ± 7.11 and 79.52 ± 21.31 mm2 in the MISS and ESS groups, respectively. ESS was also associated with a higher mean difference in the foraminal area postoperatively (72 ± 1 vs. 35.81 ± 11.3 mm2 in the MISS and ESS groups, respectively), but it was comparable to MISS in terms of the foraminal height (0.32 ± 0.037 vs. 0.29 ± 0.03 cm in the MISS and endoscopic groups, respectively).

CONCLUSIONS

 Compared with MISS, ESS was associated with improved radiologic parameters, including spinal canal area and neural foraminal area in the lumbar spinal segments. Both techniques led to the same endpoint of neural decompression when starting with a more severe compression. However, the present data do not allow the correlation of the radiographic results with the related clinical outcomes.

Clinical Efficacy of Interlaminar and Transforaminal Spinal Endoscopy in the Treatment of Lumbar Spinal Stenosis

Purpose

To compare the application effect of interlaminar technique (ILT) and transforaminal technique (TFT) spinal endoscopies in lumbar spinal stenosis (LSS) treatment.

Material and Methods

The data of 46 patients aged 65 years or older diagnosed with LSS between January 2019 and March 2021 were retrospectively reviewed in this study. They underwent ILT (21 patients) or TFT (25 patients) spinal endoscopy surgery, and outcomes were analyzed utilizing the visual analog scale (VAS), Oswestry disability index (ODI), and Japanese orthopedic association (JOA) scale. Lumbar stability was also evaluated using the change in dynamic position X-ray of the spine. We also built three-dimensional (3D) finite element of ILT and TFT spine models and compared them with the stability of the intact spine.

Results

The ILT group had a longer operation time than the TFT group, and patients in ILT and TFT groups had comparable VAS scores for back pain. However, the TFT group had higher VAS scores for leg pain than the ILT group 3, 6 and 12 months postoperatively. The JOA and ODI scores of the 2 groups improved after surgery, and there were statistical differences between the 2 groups at 6 and 12 months follow-up, which proved that functional recovery was better in ILT group. The pre- and postoperative change in dynamic position X-ray of the spine proved that ILT and TFT would not destroy the spine's stability. 3D finite element lumbar spine model analysis also demonstrated this point.

Conclusion

Both ILT and TFT can provide good clinical outcomes; compared with TFT, the ILT approach provided more thorough decompression and was more suitable for treating LSS.

Endoscopic Spinal Surgery (BESS and UESS) Versus Microscopic Surgery in Lumbar Spinal Stenosis: Systematic Review and Meta-Analysis

STUDY DESIGN

Systematic Review and Meta-Analysis.

OBJECTIVES

Various minimally invasive surgical techniques have been developed as alternatives to conventional surgery. According to recent studies, endoscopic spinal surgery (ESS) (biportal ESS [BESS] or uniportal ESS [UESS]) is more favorable compared with microscopic spinal surgery (MSS). This systematic review and meta-analysis aimed to assess the latest evidence on the use of ESS compared with MSS in lumbar spinal stenosis.

METHODS

A systematic electronic search using PubMed, Embase, Cochrane Central Database, and Korea Med was performed until December 2019 to identify studies that compared ESS and MSS in patients with lumbar spinal stenosis.

RESULTS

Overall, 1167 patients were included from three randomized controlled trials, six retrospective cohorts, and two prospective case-control studies. This review only presented 3 direct comparative studies. The study had inherent limitations specifically in terms of the study design. Meta-analysis of hospital stay (days) showed significant difference between BESS and MSS, UESS and MSS, BESS +UESS, and MSS at the final follow-up (95% confidence interval [CI]: -3.66 to -.77; P = .003; I² = 97%, 95% CI: -2.95 to -1.22; P <.00001; I² = 90%, and 95% CI: -2.89 to -1.48; P <.00001; I² = 96%, respectively). However, meta-analysis showed no significant difference in other results.

CONCLUSIONS

Although a shorter duration of hospital stay was observed in ESS, there were no significant differences in efficacy and safety between ESS and MSS. Further studies are required to validate these results.

Microendoscopic Lumbar Posterior Decompression Surgery for Lumbar Spinal Stenosis: Literature Review

Lumbar spinal stenosis (LSS) is a common disease in the elderly, mostly due to degenerative changes in the lumbar spinal complex. Decompression surgery is the standard surgical treatment for LSS. Classically, total laminectomy—which involves resection of the spinous process, entire laminae and medial facet—has been the standard decompression technique; however, it can cause post-surgical instability. To overcome this disadvantage, various minimally invasive techniques that preserve the stabilization structures of the spine have been developed, and surgeons have begun to re-evaluate decompression surgery from the standpoint of reduced invasiveness and cost. More than two decades have passed since the introduction of microendoscopic spine surgery, and studies continue to shed light on its advantages and limitations as new knowledge becomes available. This article is a narrative review of the available literature, along with authors’ experience, regarding the indications, surgical techniques, clinical outcomes, and limitations/complications of microendoscopic decompression for LSS.

Epidural hemostasis by autologous fat graft in minimally invasive surgery for lumbar spinal stenosis: In vivo experimental study

BACKGROUND

Epidural hemostasis needs to use small, adapted material in minimally invasive surgery, including bilateral decompression via a unilateral approach for lumbar spinal stenosis. Most surgeons avoid external material for hemostasis because of possible neural tissue damage or complications. We compared epidural hemostasis in minimally invasive surgery by fat graft versus gelatin sponge.

METHODS

The design was a prospective randomized controlled in-vivo human experimental study. The 24 levels operated on for lumbar spinal stenosis were evaluated in two groups: Group A (control group: gelatin sponge) and Group B (experimental group: fat graft). International Normalized Ratio and Prothrombin Time were assessed preoperatively. Number of cotton hemostats and systolic and diastolic blood pressure were assessed intraoperatively. Epidural hemorrhage area, spinal cord size and ratio of epidural hemorrhage area to spinal cord size were evaluated on early postoperative lumbar MRI.

RESULTS

Mean epidural hemorrhage area in groups A and B was respectively 1.3±0.5 and 1.2±0.6cm², and mean spinal cord size 1.2±0.6 and 1.8±0.6cm² on early postoperative axial lumbar MRI. The two groups did not significantly differ in ratio of epidural hemorrhage/spinal cord size or number of intraoperative hemostats (P=0.36, and P=0.71).

CONCLUSIONS

The autologous fat graft ensured sufficient and safe epidural hemostasis without serious adverse events in minimally invasive spinal surgery, and is preferable as autologous tissue is easily and quickly harvested. The surgeon feels safe with this technique and does not need external hemostatic agents.

Biportal endoscopic decompression vs. microscopic decompression for lumbar canal stenosis: A systematic review and meta-analysis

Lumbar decompressive surgery is the gold standard treatment for lumbar spinal stenosis. Minimally invasive surgical techniques have been introduced with the aim of reducing the morbidity associated with open surgery. The purpose of the present study was to systematically search the literature and perform a meta-analysis of studies comparing the outcomes between biportal endoscopic technique and microscopic technique for lumbar canal stenosis decompression. A comprehensive search of the PubMed, Google Scholar, Web of Science, Embase and the Cochrane Library databases was performed to identify relevant articles up to 15th of December 2019. Eligible studies were retrieved, data were extracted by two authors independently and risks of bias were assessed. A total of six studies involving 438 patients were selected for review. The results of the pooled analysis indicated similar operative times [mean difference (MD), -3.41; 95% CI, -10.78-3.96; P<0.36], similar complications (MD, 0.70; 95% CI, 0.33-1.46; P=0.34), similar visual analogue scale scores for back and leg pain at the time of the final follow-up and similar Oswestry disability indexes (MD, -0.28; 95% CI, -1.25-0.69; P=0.58) for the two procedures. In conclusion, biportal endoscopic technique is a viable alternative to microscopic technique for lumbar canal stenosis decompression with similar operative time, clinical outcomes and complications.

Scoliosis, diabetes mellitus and total laminectomy at the 4th lumbar vertebra are independent risk factors for post-laminectomy fracture around the isthmus

OBJECTIVE

We aimed to identify the risk factors and clinical outcomes for post-laminectomy fracture around the isthmus, which can cause back pain or radiculopathy.

METHODS

We performed a retrospective cohort study involving all patients who underwent laminectomy splitting the spinous process for lumbar spinal stenosis between 2010 and 2014. The primary outcome measure was post-laminectomy fracture around the isthmus. Clinical outcomes were evaluated based on reoperation rate. To evaluate risk factors for fracture, the following parameters were collected: (1) patient characteristics and concomitant diabetes mellitus, (2) lumbar scoliosis and sagittal alignment parameters, and (3) surgical data, such as rate of total laminectomy. Logistic regression analysis was performed to identify the independent risk factors for post-laminectomy fracture.

RESULTS

Twelve of the 92 patients suffered a post-laminectomy fracture around the isthmus. Logistic regression analysis revealed that diabetes mellitus (odds ratio [OR]: 15.41; 95% confidence interval [CI]: 2.93-80.98; P=0.001), L4 total laminectomy (OR: 14.68; 95% CI: 1.51-142.76; P=0.021), and lumbar scoliosis (OR: 5.72; 95% CI: 1.16-28.21; P=0.032) were independent risk factors. The fracture group included 2 patients (16.7%) who required reoperation at the decompression level for recurrent leg pain, whereas the non-fracture group included 2 (2.5%) who underwent reoperation at a level different from the index procedure.

CONCLUSIONS

Post-laminectomy fractures around the isthmus were significantly associated with scoliosis, diabetes mellitus, and total laminectomy at L4. Total laminectomy at L4 is best avoided to reduce the risk of post-laminectomy fracture in patients with scoliosis or diabetes mellitus.

Ipsilateral Pedicle Stress Fracture After Endoscopic Foraminal Decompression for Patient with Isthmic Spondylolisthesis

BACKGROUND

Minimally invasive endoscopic spine surgery is useful for the treatment of various spinal conditions. Although surgery-related complications such as dural injury, exiting nerve root injury, incomplete decompression, and hematoma have been reported, there are few reports of late complications after endoscopic surgery.

CASE DESCRIPTION

A 51-year-old man complained of radiating pain to the right leg. The patient underwent endoscopic foraminal decompression under the diagnosis of foraminal stenosis with isthmic type spondylolisthesis (L5-S1). The lower extremity radiating pain was improved after surgery. Six weeks after surgery, the patient's symptoms recurred. The patient experienced a sudden onset of severe low back pain, which was aggravated by any motion of the lumbar spine. Computed tomography scan and magnetic resonance imaging revealed a fracture line with a sclerotic margin at the base of the right pedicle at the L5 level. Because the symptoms significantly interfered with his normal activities of daily living, the patient was treated with a total laminectomy, followed by posterior instrumented fusion. As the indication for endoscopic spinal surgery is widening, endoscopic decompression surgery is being performed for patients with low-grade lumbar spondylolisthesis, regardless of the presence of advanced spinal instability. However, endoscopic decompression surgery may cause damage to the posterior facet joint, which may have worsened the instability and lead to late complications such as progression of spondylolisthesis and pedicle stress fracture.

CONCLUSIONS

The surgeon should carefully review risk factors such as isthmic type spondylolisthesis before planning spine surgery and minimize facet joint damage during endoscopic decompression.

Dural Tears in Percutaneous Biportal Endoscopic Spine Surgery: Anatomical Location and Management

OBJECTIVE

To determine the rate and anatomical location of dural tears associated with spinal surgery using a percutaneous biportal endoscopic surgery (PBES) technique. We investigated the relationship between dural tears and the type of procedure and type of instrument used.

METHODS

We retrospectively analyzed 643 PBES cases by reviewing the medical records, operative records, and operative videos. Incidental durotomy was identified in 29 cases. We analyzed the size and anatomical location of the dural tears, the surgical instrument that caused the tear, and the technique used to seal the tear.

RESULTS

The dural tear incidence was 4.5% (29 of 643 cases). Tears in the exiting nerve area (2 cases; 6.9%) had mainly been caused by curettage, tears in the thecal sac area (18 cases; 62.1%) were associated with electric drill and forceps use; and tears in the traversing nerve area were associated with the use of a Kerrison punch (9 cases; 31%). Of the 29 cases of dural tear, 12 were treated with in-hospital monitoring and bed rest, 14 were treated with a fibrin sealant, 2 were treated with a nonpenetrating titanium clip, and 1 was converted to microscopic surgery. One case of postoperative meningocele after conservative treatment required endoscopic revision surgery to close the dural tear.

CONCLUSIONS

Most cases of incidental dural tear during PBES were treated with an endoscopic procedure. The incidence of dural tear was no greater than that associated with microscopic surgery. Our management strategy for incidental dural tears during PBES has been shown to be safe and effective.

Five-year Reoperation Rates and Causes for Reoperations Following Lumbar Microendoscopic Discectomy and Decompression

STUDY DESIGN

Retrospective study of prospectively collected outcome data.

OBJECTIVE

The aim of this study was to investigate reoperation cases and determine whether or not the experience period of a single surgeon was associated with the causes of reoperations following lumbar microendoscopic discectomy for disc herniation (MEDH) and microendoscopic decompression for spinal stenosis (MEDS).

SUMMARY OF BACKGROUND DATA

There have been few studies that investigated reoperation cases following MEDH and MEDS.

METHODS

Between June 2005 (first experience of MEDH) and September 2013, the same surgeon had been using MEDH and/or MEDS on 441 consecutive patients. The follow-up rate was 89.3%. The causes and rates of reoperations (RORs) were determined at 5 years after the initial operations. We also investigated the experience period of a single surgeon (EPS, interval between June 2005 and initial operation: median, 37 months).

RESULTS

The 5-year reoperation rate for all patients combined was 12.4% (49/394). The main causes for reoperations were recurrence of disc herniation (ROR, 7.01%) and increase of postoperative spondylolisthesis and/or instability (ROR, 9/394 = 2.28%); two of the nine cases were caused by excessive decompression, and the EPSs were 11 and 16 months. The other causes for reoperations were postoperative epidural hematoma (ROR, 0.76%; median EPS, 20 months), insufficient decompression (ROR, 0.25%; EPS, 17 months), and residual segmental scoliosis (ROR, 7.69%); two segmental scoliosis cases did not provide relief from sciatica, and therefore L4/5 transforaminal interbody fusions were performed.

CONCLUSION

Postoperative epidural hematoma and excessive or insufficient decompression were often observed in the initial series of patients as the causes for reoperations. We think that it is important to be aware of and prevent such potential problems in any initial series of patients, as there are limitations to any surgical indications for the use of microendoscopic decompression for degenerative segmental scoliosis because of original traction and/or kinking of nerve roots.

LEVEL OF EVIDENCE

4.

Minimally invasive spine surgery decreases postoperative pain and inflammation for patients with lumbar spinal stenosis

In certain cases, lumbar spinal stenosis may lead to lumbar nervous disorder. A previous study indicated that minimally invasive spine surgery (MISS) presents benefits compared with conventional open surgery (COS). In the current study, the efficacy of MISS and COS for lumbar spinal stenosis patients was investigated. A total of 82 patients with lumbar spinal stenosis were enrolled and divided into two age-matched groups that received MISS (n=41) or COS (n=41). Patient parameters, including symptoms, inflammatory score, visual analog score (VAS), wound length, Oswestry Disability Index (ODI), hospital stay and postoperative outcomes were analyzed in the current study. Outcomes indicated that both MISS and COS significantly improved symptoms of lumbar spinal stenosis compared with the baseline. It was observed that MISS resulted in decreased wound length and hospital stay compared with COS for patients with lumbar spinal stenosis. The results revealed that MISS had better outcomes compared with COS in improving ODI and inflammatory score for patients with lumbar spinal stenosis. Notably, it was identified that MISS exhibited improved VAS for back and leg pain compared with the COS group for patients with lumbar spinal stenosis. In conclusion, these outcomes indicate that MISS was more effective compared with COS for improving symptoms in patients with lumbar stenosis.

Is biportal technique/endoscopic spinal surgery satisfactory for lumbar spinal stenosis patients?: A prospective randomized comparative study

BACKGROUND

Lumbar decompressive surgery is a standard surgical technique for lumbar spinal stenosis. Many new surgical techniques have been introduced, ranging from open surgery to minimally invasive procedures. Minimally invasive surgical techniques are preferred because patients experience less postoperative pain and shorter hospital stays. However, the success rate of minimally invasive techniques have been controversial. The object of this study was to assess the feasibility of spinal decompression using biportal technique/endoscopic surgery compared with microscopic surgery.

METHODS

Seventy lumbar spinal stenosis patients undergoing laminectomy were included in this study. A number table was used to randomize the patients into two groups: a biportal technique/endoscopic surgery group (BG-36) and a microscopic surgery group (OG-34). One surgeon performed either biportal technique/endoscopic decompression or microscopic decompression using a tubular retractor, depending on the group to which the patient was randomized. Perioperative data and clinical outcomes at postoperative 6 months were collected and analyzed.

RESULTS

The demographic data and level of surgery were comparable between the two groups. A shorter operation time (36 ± 11 vs 54 ± 9 min), less hemovac drain output (25.5 ± 15.8 vs 53.2 ± 32.1 ml), less opioid usage (2.3 ± 0.6 vs 6.5 ± 2.5 T) and shorter hospital stay (1.2 ± 0.3 vs 3.5 ± 0.8 days) were shown in BG. The BG experienced no significant differences in clinical outcomes compared with OG. Favorable clinical outcomes were shown at 6 months after surgery in both groups.

CONCLUSION

Lumbar decompressive surgery using biportal technique/endoscopy showed favorable clinical outcomes, less pain and a shorter hospital stay compared to microscopic surgery in patients with lumbar spinal stenosis.

Management of Dural Tears in Endoscopic Lumbar Spinal Surgery: A Review of the Literature

OBJECTIVE

The incidental dural tear is a common complication in lumbar spine surgery. It has been reported that the incidence of dural tears is much greater in endoscopic procedures. Primary closure via suturing remains challenging in endoscopic procedures. The objective of this study was to conduct a literature review on the surgical technique for dural closure and repair in endoscopic spine surgery.

METHODS

A systematic literature search was performed using the database PubMed. In total, 12 studies reported specifically about the surgical treatment for dural tear in percutaneous and tubular assisted endoscopic technique. The dural tear rate, the technique of dural closure, postoperative time of bed rest, postoperative symptoms related to cerebrospinal fluid fistula, and revision surgery were assessed.

RESULTS

The overall rate of dural tears in endoscopic spinal surgery was 2.7%, with a range from 0% to 8.6%. The incidence of a dural tear was much greater in cases with lumbar stenosis (3.7%) than in lumbar disc herniation (2.1%). The greatest rate was accompanied by resecting synovial cysts. In addition, the risk of dural tear is greater in bilateral decompression procedures via a unilateral approach. There is no consensus about the ideal technique for dural closure in endoscopic procedures. Furthermore, there is a debate whether dural tear requires surgical treatment or not.

CONCLUSIONS

An autologous muscle or fat graft in combination with fibrin glue or a fibrin-sealed collagen sponge seems to be a good and safe method for the management of dural tear in lumbar endoscopic spine surgery.

Endoscope-Assisted Abscess Drainage Secondary to Endoscope-Assisted Transforaminal Lumbar Interbody Fusion: 1-Year Follow-Up

INTRODUCTION

Endoscopic discectomy and fusions have been gaining popularity in the recent past and are noted to be safe for their application in elderly population. The procedure involves ultra-small incision for discectomy followed by placement of percutaneous screws in awake patients. Treatment of advanced spinal pathology with endoscope-assisted techniques is challenging. Although not common with the endoscopic approach, postoperative infection can be problematic, as there are no established guidelines on its management.

METHODS

A 76-year-old female patient underwent lumbar 4-5 endoscopic-assisted transforaminal lumbar interbody fusion for severe degenerative changes leading to back and radicular leg pain. She did well postoperatively and was discharged home the following day. She presented to the outside hospital with new onset of severe back pain, sepsis, and positive methicillin-susceptible Staphylococcus aureus with blood culture and demonstrated no improvement while on antibiotics.

RESULTS

Initial magnetic resonance imaging revealed postoperative changes only. With positive blood culture and localized pain, she was then offered to undergo a percutaneous drainage of the abscess. Under local anesthesia and intravenous sedation, a small pocket of collection was found along the endoscopic trajectory from previous surgery. After evacuation of the collection, the interbody device was irrigated with vancomycin through endoscope. Postoperatively, immediate symptomatic improvement was noted in back pain. She was discharged home on oxacillin and continues to do well at 12 months' follow-up with excellent fusion.

CONCLUSIONS

The present case illustrates the successful treatment of a surgical-site infection after endoscope-assisted transforaminal lumbar interbody fusion via a repeat percutaneous endoscopic approach.

Complications of Anterior and Posterior Cervical Spine Surgery

Cervical spine surgery performed for the correct indications yields good results. However, surgeons need to be mindful of the many possible pitfalls. Complications may occur starting from the anaesthestic procedure and patient positioning to dura exposure and instrumentation. This review examines specific complications related to anterior and posterior cervical spine surgery, discusses their causes and considers methods to prevent or treat them. In general, avoiding complications is best achieved with meticulous preoperative analysis of the pathology, good patient selection for a specific procedure and careful execution of the surgery. Cervical spine surgery is usually effective in treating most pathologies and only a reasonable complication rate exists.

Percutaneous biportal endoscopic decompression for lumbar spinal stenosis: a technical note and preliminary clinical results

OBJECTIVE

The use of conventional uniportal spinal endoscopic decompression surgery for lumbar spinal stenosis can be limited by technical difficulties and a restricted field of vision. The purpose of this study is to describe the technique for percutaneous biportal endoscopic decompression (PBED) for lumbar spinal stenosis and analysis of clinical postoperative results.

METHODS

The authors performed a unilateral laminotomy with bilateral foraminal decompression using a unilateral biportal endoscopic system in patients with single-level lumbar stenosis. The authors enrolled only patients who underwent follow-up for longer than 12 months after PBED. Fifty-eight patients were enrolled in this study. This approach was based on 2 portals: one portal was used for continuous irrigation and endoscopic viewing and the other portal was used to manipulate the instruments used in the decompression procedures. Clinical parameters such as the Oswestry Disability Index (ODI), Macnab criteria, and postoperative complications were analyzed.

RESULTS

Neural decompression was effectively performed in all enrolled patients. The mean ODI was significantly lower after PBED. Of 58 patients, 47 (81.0%) had a good or excellent result according to the Macnab criteria. Postoperative ODI and visual analog scale scores were significantly improved compared with preoperative values.

CONCLUSIONS

From a surgical point of view, percutaneous biportal endoscopy is very similar to microscopic spinal surgery, permitting good visualization of the contralateral sublaminar and medial foraminal areas. The authors suggest that the PBED, which is a minimally invasive procedure, is an alternative treatment option for degenerative lumbar stenosis.

Endoscopic inter laminar management of lumbar disease

Discectomy for lumbar disc provides faster relief in acute attack than does conservative management. Long-term results of open, microscopy-, and endoscopy-assisted discectomy are same. Early results of endoscopy-assisted surgery are better as compared to that of open surgery in terms of better visualization, smaller incision, reduced hospital stay, better education, lower cost, less pain, early return to work, and rehabilitation. Although microscopic discectomy also has comparable advantages, endoscopic-assisted technique better addresses opposite side pathology. Inter laminar technique (ILT) and trans foraminal technique (TFT) are two main endoscopic approaches for lumbar pathologies. Endoscopy-assisted ILT can be performed in recurrent, migrated, and calcified discs. All lumbar levels including L5-S1 level, intracanalicular, foraminal disc, lumbar canal and lateral recess stenosis, multiple levels, and bilateral lesions can be managed by ILT. Migrated, calcified discs, L5-S1 pathology, lumbar canal, and lateral recess stenosis can be better approached by ILT than by TFT. Most spinal surgeons are familiar with anatomy of ILT. It can be safely performed in foramen stenosis and in uncooperative and anxious patients. There is less risk of exiting nerve root damage, especially in short pedicles and in presence of facet osteophytes as compared to TFT. On the other hand, ILT is more invasive than TFT with more chances of perforations of the dura matter, pseudomeningocele formation, and cerebrospinal fluid fistula in early learning curve. Obtaining microsurgical experience, attending workshops, and suitable patient selection can help shorten the learning curve. Once adequate skill is acquired, this procedure is safe and effective. The surgeon must be prepared to convert to an open procedure, especially in early learning curve. Spinal endoscopy is likely to achieve more roles in future. Endoscopy-assisted ILT is a safer alternative to the microscopic technique.

Finite element analysis for comparison of spinous process osteotomies technique with conventional laminectomy as lumbar decompression procedure

PURPOSE

The purpose of this study was to evaluate and compare the biomechanical behavior of the lumbar spine after posterior decompression with the spinous process osteotomy (SPiO) technique or the conventional laminectomy (CL) technique using a finite element (FE) model.

MATERIALS AND METHODS

Three validated lumbar FE models (L2-5) which represented intact spine and two decompression models using SPiO and CL techniques at the L3-4 segment were developed. In each model, the ranges of motion, the maximal von Mises stress of the annulus fibrosus, and the intradiscal pressures at the index segment (L3-4) and adjacent segments (L2-3 and L4-5) under 7.5 Nm moments were analyzed. Facet contact forces were also compared among three models under the extension and torsion moments.

RESULTS

Compared to the intact model, the CL and SPiO models had increased range of motion and annulus stress at both the index segment (L3-4) and the adjacent segments under flexion and torsion. However, the SPiO model demonstrated a reduced range of motion and annulus stress than the CL model. Both CL and SPiO models had an increase of facet contact force at the L3-4 segment under the torsion moment compared to that of the intact model. Under the extension moment, however, three models demonstrated a similar facet contact force even at the L3-4 model.

CONCLUSION

Both decompression methods lead to postoperative segmental instability compared to the intact model. However, SPiO technique leads to better segmental stability compared to the CL technique.

Complications of minimally invasive, tubular access surgery for cervical, thoracic, and lumbar surgery

The object of the study was to review the author's large series of minimally invasive spine surgeries for complication rates. The author reviewed a personal operative database for minimally access spine surgeries done through nonexpandable tubular retractors for extradural, nonfusion procedures. Consecutive cases (n = 1231) were reviewed for complications. There were no wound infections. Durotomy occurred in 33 cases (2.7% overall or 3.4% of lumbar cases). There were no external or symptomatic internal cerebrospinal fluid leaks or pseudomeningoceles requiring additional treatment. The only motor injuries were 3 C5 root palsies, 2 of which resolved. Minimally invasive spine surgery performed through tubular retractors can result in a low wound infection rate when compared to open surgery. Durotomy is no more common than open procedures and does not often result in the need for secondary procedures. New neurologic deficits are uncommon, with most observed at the C5 root. Minimally invasive spine surgery, even without benefits such as less pain or shorter hospital stays, can result in considerably lower complication rates than open surgery.

Early surgical education of residents is safe for microscopic lumbar disc surgery

INTRODUCTION

It is a well-established dogma that many surgeons do not reach a quintessential level of their technical operative skills until successful completion of their training program. The aim of this study was to test the hypothesis that early introduction of supervised residents to non-complex spinal surgical procedures within a structured and supervised educational program does not harm the patient in terms of higher complication rates or worse pain- and health-related quality of life (HrQOL) outcomes.

METHODS

A prospective study on 102 patients undergoing surgery for lumbar disc herniation (LDH) was performed. The procedures were dichotomized into two groups according to the surgeon's level of experience: teaching cases (neurosurgical residents in the 1st to 4th year of training) and non-teaching cases (experienced board-certified faculty neurosurgeons). Pain levels (VAS) and the HrQOL using the 12-item short-form health survey (SF-12) were measured at baseline, at 4 weeks and as a survey at 1 year postoperatively. In addition, data concerning the operation and the postoperative course including common complications were assessed.

RESULTS

Intraoperative blood loss, length of surgery, as well as intra- and postoperative complications were similar between the study groups. Patients in both groups achieved equal results in terms of pain reduction after 4 weeks [mean VAS change -3.8 (teaching cases) vs. -3.1 (non-teaching cases), p = 0.25] and 1 year postoperatively [mean change in VAS -3.5 (teaching cases) vs. -3.37 (non-teaching cases), p = 0.84]. Teaching cases were 100 % (odds ratio of 1.00) as likely as non-teaching cases to achieve a favorable HrQOL response to surgery (p = 0.99).

CONCLUSIONS

Early introduction of resident surgeons to lumbar microdiscectomy can be conducted safely within a structured and supervised educational program as it neither harms the patient nor leads to worse 1-year results. Surgical resident education may thus be implemented safely in times of rigorous working laws. However, a structured education program in which the senior surgeon gives advice, guidance and communicates cautions during each resident surgery is of paramount importance to provide high-quality patient care.

A prospective study of the incidence and outcomes of incidental dural tears in microendoscopic lumbar decompressive surgery

Little information is available about the incidence and outcome of incidental dural tears associated with microendoscopic lumbar decompressive surgery. We prospectively examined the incidence of dural tears and their influence on the outcome six months post-operatively in 555 consecutive patients (mean age 47.4 years (13 to 89)) who underwent this form of surgery. The incidence of dural tears was 5.05% (28/555). The risk factors were the age of the patient and the procedure of bilateral decompression via a unilateral approach. The rate of recovery of the Japanese Orthopaedic Association score in patients with dural tears was significantly lower than that in those without a tear (77.7% vs 87.6%; p < 0.02), although there were no significant differences in the improvement of the Oswestry Disability Index between the two groups. Most dural tears were small, managed by taking adequate care of symptoms of low cerebrospinal fluid pressure, and did not require direct dural repair. Routine MRI scans were undertaken six months post-operatively; four patients with a dural tear had recurrent or residual disc herniation and two had further stenosis, possibly because the dural tear prevented adequate decompression and removal of the fragments of disc during surgery; as yet, none of these patients have undergone further surgery.

Cite this article: Bone Joint J 2014;96-B:641–5.

Lumbar spinal stenosis: therapeutic options review

Lumbar spinal stenosis (LSS) functionally impacts significant numbers of Americans per year. Current estimates place the number of Americans suffering from senescent lumbar spinal stenosis at 400,000. The prevalence of this disorder in patients ranging from 60 to 69 years of age is very high. Forty-seven percent of this age group have mild to moderate stenosis, and 19.7% have severe stenosis. As the baby boomer generation gets older, 10,000 individuals attain the age of 65 years every day in United States. LSS is becoming very common and will be a major healthcare issue as the population ages. Although LSS is not life threatening, it can cause substantial disability with limitations to performing daily activities, and thus, the associated negative impact on quality of life (QOL). This article reviews the pathophysiology and current treatment options for LSS, focusing on evidence-based treatment options.

Minimally invasive lumbar decompression for the treatment of spinal stenosis of the lumbar spine

SUMMARY Lumbar spinal stenosis is one of the most common degenerative diseases of the elderly population, and a major cause of debilitating pain and decreased function. Lumbar spinal stenosis is almost always associated with neurogenic claudication characterized as pain worsened by standing or walking and relieved by lumbar flexion or sitting. While initial treatment of lumbar spinal stenosis may involve conservative therapies, as patients become more symptomatic the traditional treatment path has generally led to open laminectomy and other invasive, potentially destabilizing, procedures. More recently, less invasive alternatives to wide laminectomy have been developed. This article describes a new method of percutaneous lumbar decompression for treatment of neurogenic claudication secondary to lumbar spinal stenosis, the minimally invasive lumbar decompression procedure. We review the steps of successfully decompressing the hypertrophic ligamentum flavum and lamina, thereby alleviating pressure on neural structures. This is a major innovation in patient care and a step to reduce risks while minimizing costs.

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.

Primary closure of inadvertent durotomies utilizing the U-Clip in minimally invasive spinal surgery

STUDY DESIGN

Retrospective clinical cohort study.

OBJECTIVE

To examine performance of the U-Clip for the closure of inadvertent durotomy occurring during minimally invasive spinal surgery.

SUMMARY OF BACKGROUND DATA

Primary closure of inadvertent durotomies that occur during minimally invasive spinal surgery can be technically difficult to accomplish when using standard knot-tying and suture management techniques, owing to the narrow and deep surgical corridor afforded by tubular retraction systems. The U-Clip is a novel device that can achieve tight tissue approximation without the need for knot-tying and excessive suture manipulation, making it ideally suited for use in minimally invasive spinal surgeries.

METHODS

We performed a retrospective review of patients who underwent minimally invasive decompressive procedures complicated by durotomy and repaired using U-Clips for the period January 2008 to January 2010. A total of seven patients were identified.

RESULTS

Four of the seven patients were male. Six patients underwent lumbar laminectomy or discectomy. One patient underwent resection of a cervical synovial cyst. In each patient, the durotomy was repaired primarily using U-Clips. All six lumbar patients were discharged home on the same day, and the remaining patient was discharged the following morning. Mean follow-up was 6.3 months. No patient experienced symptoms related to persistent cerebrospinal fluid leakage.

CONCLUSION

Primary closure of an inadvertent durotomy occurring during minimally invasive spinal surgery can be effectively achieved using the self-closing U-Clip device.

Comparative analysis of perioperative surgical site infection after minimally invasive versus open posterior/transforaminal lumbar interbody fusion: analysis of hospital billing and discharge data from 5170 patients

Object

Surgical site infection (SSI) after lumbar fusion results in significant patient morbidity and associated medical resource utilization. Minimally invasive (MI) techniques for posterior/transforaminal lumbar interbody fusion (P/TLIF) were introduced with the goals of smaller wounds, less tissue trauma, reduced blood loss, and quicker postoperative recovery, while maintaining comparable surgical results. Studies with sufficient power to directly compare the incidence of SSI following MI versus open P/TLIF procedures have been lacking. Furthermore, the direct medical cost associated with the treatment of SSI following the P/TLIF procedure is poorly understood and has not been adequately assessed. Thus, the aim in the present study was to determine the incidence of perioperative SSI in patients undergoing MI versus open P/TLIF and the direct hospital cost associated with the diagnosis and management of SSI after P/TLIF as reported in a large administrative database.

Methods

The authors retrospectively reviewed hospital discharge and billing records from the Premier Perspective Database for 2003 to 2009 to identify patients undergoing 1- or 2-level MI or open P/TLIF for lumbar spondylotic disease, disc degeneration, or spondylolisthesis. The ICD-9-CM procedure codes were used to identify patients undergoing P/TLIF and those experiencing SSI. Infection-related costs were obtained from the total costs incurred by the hospital for SSI-related care provided during inpatient or hospital outpatient encounters.

Results

Five thousand one hundred seventy patients undergoing P/TLIF were identified. Demographic profiles, including the Charlson Comorbidity Index, were similar between MI and open cohorts. Overall, 292 patients (5.6%) experienced an SSI with a mean direct cost of $15,817 per SSI. For 1-level MI versus open P/TLIF, the incidence of SSI (38 [4.5%] vs 77 [4.8%], p = 0.77) and the mean SSI-associated cost per P/TLIF ($684 vs $724, p = 0.680) were similar. For 2-level MI versus open P/TLIF, the incidence of SSI (27 [4.6%] vs 150 [7.0%], p = 0.037) and mean SSI-associated cost per P/TLIF ($756 vs $1140, p = 0.030) were both significantly lower among MI-treated patients. In a multivariate model that accounted for differences in demographics and patient severity, open fusion was associated with a strong trend of increased incidence of SSI as compared with MI fusion (OR 1.469, 95% CI 0.959–2.250).

Conclusions

In this multihospital study, the MI technique was associated with a decreased incidence of perioperative SSI and a direct cost savings of $38,400 per 100 P/TLIF procedure when used in 2-level fusion. There was no significant difference in the incidence of SSIs between the open and MI cohorts for 1-level fusion procedures. The results of this study provide further evidence of the reduced patient morbidity and health care costs associated with MI P/TLIF.

A novel simulation model for minimally invasive spine surgery

OBJECTIVE

Minimally invasive spine surgery (MISS) is among the fastest growing technologies in general neurosurgical practice. In addition, great demand exists to teach these skills to neurosurgery residents. With newly enforced work hour restrictions, opportunities to acquire these skills are limited, necessitating development of alternative strategies of education. We describe a novel simulation model for MISS supplemented by resident self-assessment analysis and evaluation.

METHODS

The simulator was constructed using a nontransparent Plexiglas frame supplemented with a modified halo frame on which to affix spine specimens. Interchangeable copper tubing was affixed to a 360-degree pivot system to replicate a working portal. Deer skulls and spines were then collected and prepared accordingly. Laboratory exercises were based on the resident's level of training with emphasis on proper drilling techniques. Eight neurosurgery residents were asked to complete the exercises and complete a self-assessment survey regarding their competence level on a scale of 0 to 5, both before and after completing the skill sets. Additionally, they were asked to complete an exit survey that was used to assess the simulation exercises.

RESULTS

All exercises were completed successfully with the exception of placing 2 separate pedicle screws through the same portal, which posed difficulty on some specimens because of the of lack of lordosis of the specimens, leading to unfavorable trajectories using a free-hand technique. With regard to the resident self-assessment analysis, the mean confidence rating for performing an MISS laminectomy improved by a difference of 1.25 points (n = 8; 95% confidence interval, 0.66-1.84; P = 0.0015), from 2.50 to 3.75 before and after simulation exercises, respectively, and reached statistical significance. For the senior-level residents, the mean confidence rating for performing MISS placement of pedicle screws using a free-hand technique improved by a difference of 1.00 (n = 3; 95% confidence interval, -1.48-3.48; P = 0.225), from 3.33 to 4.33 before and after simulation exercises, respectively. Results of the exit survey were encouraging.

CONCLUSION

The MISS simulator is a feasible, inexpensive, and reproducible adjunct to neurosurgery resident training and provides a new teaching method for spine surgery. Further investigation of this technology is warranted, although multicenter, randomized, controlled trials assessing its validity may not be practical because of ethical constraints with regard to patient safety.

Endoscopic lumbar discectomy: Experience of first 100 cases

BACKGROUND

Various modalities of treatment from standard discectomy, microdiscectomy, percutaneous discectomy, and transforaminal endoscopic discectomy have been in use for lumbar intervertebral disc prolapse. The access to spine is kept to a minimum without stripping paraspinal muscles minimizing muscle damage by posterior interlaminar endoscopic approach. The aim of this study was to evaluate technical problems, complications, and overall initial results of microendoscopic discectomy.

MATERIALS AND METHODS

First 100 consecutive cases aged 19-65 years operated by microendoscopic dissectomy between August 2002 - December 2005 are reported. All patients with single nerve root lesions including sequestrated or migrated and selected central disc at L4-5 and L5-S1 were included. The patients with bilateral radiculopathy were excluded. All patients had preoperative MRI and first 11 patients had postoperative MRI to check the adequacy of decompression. Diagnostic selective nerve root blocks were done in selective cases to isolate the single root lesion when MRI was inconclusive (n=7). All patients were operated by a single surgeon with the Metrx system (Medtronics). 97 were operated by 18-mm ports, and only three patients were operated by 16-mm ports. Postoperatively, all patients were mobilized as soon as the pain subsided and discharged within 24-48 h postsurgery. Patients were evaluated for technical problems, complications, and overall results by modified Macnab criteria. Patients were followed up at 2, 6, and 12 weeks.

RESULTS

The mean follow up was 12 months (range 3 months - 4 years). Open conversion was required in one patient with suspected root damage. Peroperatively single facet removal was done in 5 initial cases. Minor dural punctures occurred in seven cases and root damage in one case. The average surgical time was 70 min (range 25-210 min). Average blood loss was 20-30 ml. Technical difficulties encountered in initial 25 cases were insertion of guide pin, image orientation, peroperative dissection and bleeding problems, and reaching wrong levels suggestive of a definitive learning curve. Postoperative MRI (n=11) showed complete decompression. Overall 91% of patients had good-to-excellent results, with four patients having recurrence of whom three were reoperated. Four patients had postoperative discitis. One of the patients required fusion for discitis and rest were managed conservatively. One patient had root damage to L5 root that had paresthesia in L5 region even on 4 years of follow-up.

CONCLUSION

Microendoscopic discectomy is minimally invasive procedure for discectomy with early encouraging results. Once definite learning curve was over and expertise is acquired, the results of this procedure are acceptable safe and effective.

Surgical site infection rates after minimally invasive spinal surgery

OBJECT

Postoperative surgical site infections (SSIs) have been reported after 2-6% of spinal surgeries in most large series. The incidence of SSI can be < 1% after decompressive procedures and > 10% after instrumented fusions. Anecdotal evidence has suggested that there is a lower rate of SSI when minimally invasive techniques are used.

METHODS

A retrospective review of prospectively collected databases of consecutive patients who underwent minimally invasive spinal surgery was performed. Minimally invasive spinal surgery was defined as any spinal procedure performed through a tubular retractor system. All surgeries were performed under standard sterile conditions with preoperative antibiotic prophylaxis. The databases were reviewed for any infectious complications. Cases of SSI were identified and reviewed for clinically relevant details. The incidence of postoperative SSIs was then calculated for the entire cohort as well as for subgroups based on the type of procedure performed, and then compared with an analogous series selected from an extensive literature review.

RESULTS

The authors performed 1338 minimally invasive spinal surgeries in 1274 patients of average age 55.5 years. The primary diagnosis was degenerative in nature in 93% of cases. A single minimally invasive spinal surgery procedure was undertaken in 1213 patients, 2 procedures in 58, and 3 procedures in 3 patients. The region of surgery was lumbar in 85%, cervical in 12%, and thoracic in 3%. Simple decompressive procedures comprised 78%, instrumented arthrodeses 20%, and minimally invasive intradural procedures 2% of the collected cases. Three postoperative SSIs were detected, 2 were superficial and 1 deep. The procedural rate of SSI for simple decompression was 0.10%, and for minimally invasive fusion/fixation was 0.74%. The total SSI rate for the entire group was only 0.22%.

CONCLUSIONS

Minimally invasive spinal surgery techniques may reduce postoperative wound infections as much as 10-fold compared with other large, modern series of open spinal surgery published in the literature.

A new endoscopic spine system: the first results with "Easy GO"

PURPOSE

Endoscopy meets increasing interest by spine surgeons. However, endoscopic results are diverging and many spinal endoscopic systems are difficult to apply and handle.

METHODS

A system for endoscopic spinal surgery was developed where the main goals were: (1) easy intraoperative handling with standard microsurgical techniques, and (2) avoidance of a prolonged learning curve. The system consists of various dilators, two different work sheaths, two different 30 degrees endoscopes, and an endoscope holder.

RESULTS

Between August 2006 and April 2008, 80 spinal surgeries were performed in degenerative lumbar spine cases (mean age 52 years, range 22-85 years). Intraoperatively, the system was easy to handle. Standard microsurgical techniques were used. Mean surgical time scored 75 min (range 28-168 min). There was no intraoperative complication, no new postoperative deficit and no infection. In four cases, the endoscope was abandoned and the procedure microsurgically continued (5%). At the last follow-up (mean FU 10 months, range 2 weeks up to 21 months), 89% of the patient were pain free (71/80). Four patients suffered from recurrent disc prolapses (5%). Another five patients (6%) were not satisfied without evidence of re-prolaps. Of those who answered the questionnaire of patient satisfaction, 83% (45/54) considered their postoperative status as excellent, 13% as good (7/54), 4% were not satisfied (2/54).

CONCLUSIONS

The Easy GO system was easy and safe to handle with the standard bimanual microsurgical technique and good postoperative results. Further studies are needed to show a significant advantage of the technique in comparison to the microsurgical standard procedure.

Prevalence and clinical features of intraspinal facet cysts after decompression surgery for lumbar spinal stenosis

Object

Although many cases of primary intraspinal facet cysts in the lumbar spine have been reported, there have only been a few reports of postoperative intraspinal facet cysts in the lumbar spine. The purpose of this study was to investigate the prevalence and clinical features of postoperative intraspinal facet cysts in the lumbar spine.

Methods

Data from 81 patients undergoing microendoscopic posterior decompression to treat lumbar spinal stenosis were reviewed. The development of a postoperative intraspinal facet cyst was observed using MR imaging during 1 year after surgery. If the patient demonstrated a postoperative intraspinal facet cyst, additional MR imaging was performed to evaluate the natural course of the cyst. Furthermore, the authors conducted a comparative evaluation to identify the factors associated with the causes of cyst development.

Results

A postoperative intraspinal facet cyst developed in 7 patients (8.6%) during 1 year after surgery. Spondylotic spinal stenosis, degenerative spondylolisthesis, and degenerative scoliosis were revealed before surgery in 2, 4, and 1 patient, respectively. In 5 patients, the cysts developed within 3 months after surgery. Although 3 patients exhibited symptoms caused by cyst development, all symptoms were relieved by conservative treatment. On radiographic evaluations, postoperative segmental spinal instability, including a progression of spondylolisthesis and disc degeneration, was revealed in 6 (86%) of the 7 patients. Spontaneous regression of the cysts was observed in 5 (71%) of these 7 patients. On comparative evaluation of patients with and without postoperative intraspinal facet cysts, the presence of segmental spinal instability before surgery (including degenerative spondylolisthesis) and the appearance of postoperative segmental spinal instability were related to the development of the cysts.

Conclusions

The prevalence of postoperative intraspinal facet cysts, including asymptomatic cysts, was 8.6% during 1 year after decompression surgery for lumbar spinal stenosis. The development of postoperative intraspinal facet cysts was related to the presence of segmental spinal instability before surgery (including degenerative spondylolisthesis) and postoperative segmental spinal instability, including a progression of spondylolisthesis and disc degeneration after surgery. A postoperative intraspinal facet cyst, which can be expected to regress spontaneously with a probability > 50%, should be recognized as one of the postoperative complications of decompression surgery for lumbar spinal stenosis.

Operative results and learning curve: microscope-assisted tubular microsurgery for 1- and 2-level discectomies and laminectomies

Object

The authors present their clinical results and the learning curve associated with the use of tubular retractors for 1- and 2-level lumbar microscope-assisted discectomies and laminectomies.

Methods

The study involves a retrospective and prospective analysis of 230 patients who underwent noninstrumented minimally invasive procedures for degenerative lumbar spinal disease between 2004 and 2007. Data on patient demographic characteristics and operative results, including length of stay, blood loss, operative times, and surgical complications were collected. Clinical outcomes were assessed based on pre- and postoperative Visual Analog Scale scores, Oswestry Disability Index values, and the Macnab outcome scale scores.

Results

The results showed characteristic differences in blood loss and operating times between 1- and 2-level procedures and between discectomies and laminectomies. A significant learning curve was seen by a decrease in operating time for 1- level discectomies and 2-level laminectomies. Major complications were not observed.

Conclusions

The use of tubular retractors for microsurgical decompression of degenerative spinal disease is a safe and effective treatment modality. As with other techniques, minimally invasive procedures are associated with a significant learning curve. As surgeons become more comfortable with the procedure, its applications can be expanded to include, for example, spinal instrumentation and deformity correction.