Early Clinical Outcomes of Percutaneous Endoscopic Lumbar Discectomy for L4-5 Highly Down-Migrated Disc Herniation: Interlaminar Approach Versus Transforaminal Approach.

OBJECTIVE: This study is a retrospective evaluation of patients with L4-5 highly down-migrated lumbar disc herniation (LDH) operated with interlaminar endoscopic lumbar discectomy (IELD) versus transforaminal endoscopic lumbar discectomy (TELD). METHODS: From January 2015 to December 2018, 77 patients with L4-5 highly down-migrated LDH were divided into 2 groups according to different surgical approaches. There were 40 patients who underwent IELD, and 37 patients who underwent TELD. The operation time, hospital stay, Oswestry Disability Index, clinical outcome according with modified MacNab criteria, Visual Analog Scale (VAS) scores, and complications were compared between the IELD and TELD groups. RESULTS: Seventy-seven patients were included, 40 and 37 patients underwent IELD and TELD, respectively. The IELD and TELD groups both achieved a significant improvement in Oswestry Disability Index, back and leg VAS scores, and clinical outcome postoperation. Mean operating and x-ray times during operation were significantly shorter in the IELD group than in the TELD group (41.8 vs. 50.3, 1.8 vs. 13.7). There were 3 patients who experienced recurrence in the IELD group and 2 in the TELD group. In the TELD group, there were 3 patients who required revision surgery due to incompletely removed disc fragment. All patients in the IELD group were treated successfully. There was no other complication in these cases. CONCLUSIONS: Both IELD and TELD could be a good alternative option for highly down-migrated LDH in L4-L5. IELD may have advantages in operation time and x-ray times during operation compared with TELD.

Foraminoplasty affects the clinical outcomes of discectomy during percutaneous transforaminal endoscopy: a two-year follow-up retrospective study on 64 patients.

Objective: The aim of this study was to assess the significance of how the degree of injury of the facet joint affects clinical outcomes in foraminoplasty.Methods: We retrospectively enrolled 64 patients treated with percutaneous endoscopic transforaminal discectomy with foraminoplasty (PETDF) from January of 2015 to December of 2016. The patients were divided into two groups depending on whether the articular surface of the facet joint was damaged. Preoperative, perioperative, demographic data, and radiographic parameters for these two groups were extracted and compared.Results: There were no significant differences between the two groups in terms of the duration of operation (p = 0.331), intraoperative blood loss volume (p = 0.631), the weight of disc (p = 0.274) or cut bone (p = 0.526). There were no significant differences between the two groups for VAS or ODI at the same time point (p > 0.05). There were significant differences in the VAS scores of low-back pain at 24 h and 24 months after surgery in the injured group. There were significant differences in ISH, ISA, rate of lumbar instability, recurrent herniation, and Macnab scores between the two groups at 24 months after surgery (p < 0.05). The regression equation between ISA and ISH was Y = 4.237 + 0.565x (where Y denotes an increase of ISA; X, reduction of ISH; F = 6.219, p = 0.015). The Poisson ratio was 0.363 (p = 0.003).Conclusions: PETDF is effective and safe for the treatment of lumbar disc herniation. However, when foraminoplasty destroys the articular surface of the facet joint, there may be increases in lumbar instability and recurrence rate post-operation.

The Evolution of Transforaminal Endoscopic Spine Surgery.

Transforaminal endoscopic spine surgery (T-ESS) has become a well-accepted technique. The first attempts at percutaneous discectomy by Kambin and Hijikata opened a new chapter of endoscopic spine surgery. By the last quarter of the twentieth century, spine surgeons had begun to adopt this novel technique. Many researchers helped advance endoscopic spine surgery, but the turning point was the description of a safe transforaminal triangle of safety by Parviz Kambin. Since then, the indications for T-ESS have increased as a result of the description of different surgical approaches such as inside-out, outside-in, and half-and-half. We present a review of crucial historical advancements in T-ESS and also discuss the evolution of endoscopes, the techniques used, development of endoscopic instruments and equipment, transforaminal thoracic endoscopy, transforaminal endoscopic interbody fusions, the growth of extended indications, and the future direction of T-ESS. This review provides a detailed description of key historical moments and a bird's-eye view of the vast scope of T-ESS.

Evolution of Minimally Invasive Lumbar Spine Surgery.

Spine surgery has evolved over centuries from first being practiced with Hippocratic boards and ladders to now being able to treat spinal pathologies with minimal tissue invasion. With the advent of new imaging and surgical technologies, spine surgeries can now be performed minimally invasively with smaller incisions, less blood loss, quicker return to daily activities, and increased visualization. Modern minimally invasive procedures include percutaneous pedicle screw fixation techniques and minimally invasive lateral approach for lumbar interbody fusion (i.e., minimally invasive transforaminal lumbar interbody fusion, extreme lateral interbody fusion, oblique lateral interbody fusion) and midline lumbar fusion with cortical bone trajectory screws. Just as evolutions in surgical techniques have helped revolutionize the field of spine surgery, imaging technologies have also contributed significantly. The advent of computer image guidance has allowed spine surgeons to advance their ability to refine surgical techniques, increase the accuracy of spinal hardware placement, and reduce radiation exposure to the operating room staff. As the field of spine surgery looks to the future, many novel technologies are on the horizon, including robotic spine surgery, artificial intelligence, and machine learning to help improve preoperative planning, improve surgical execution, and optimize patient selection to ensure improved postoperative outcomes and patient satisfaction. As more spine surgeons begin incorporating these novel minimally invasive techniques into practice, the field of minimally invasive spine surgery will continue to innovate and evolve over the coming years.

Recurrent disc herniation following percutaneous endoscopic lumbar discectomy preferentially occurs when Modic changes are present.

OBJECTIVE: To investigate the relationship between Modic changes (MCs) and recurrent lumbar disc herniation (rLDH) and that between the herniated disc component and rLDH following percutaneous endoscopic lumbar discectomy (PELD). METHODS: We included 102 (65 males, 37 females, aged 20-66 years) inpatients who underwent PELD from August 2013 to August 2016. All patients underwent CT and MRI preoperatively. The presence and type of Modic changes were assessed. During surgery, the herniated disc component of each patient was classified into two groups: nucleus pulposus group and hyaline cartilage group. The association of herniated disc component with Modic changes was investigated. The incidence of rLDH was assessed based on a more than 2-year follow-up. RESULTS: In total, 11 patients were lost to follow-up; the other 91 were followed up during 24-60 months. Of the 91 patients, 99 discs underwent PELD; 28/99 (28.3%) had MCs. Type I and II MCs were seen in 9 (9.1%) and 19 (19.2%), respectively; no type III MCs were found. Among 28 endplates with MCs, according to the herniated disc component, 18/28 (64.3%) showed evidence of hyaline cartilage in the intraoperative specimens, including 6/9 and 12/19 endplates with type I and II MCs, respectively. Among 71 endplates without MCs, 14/71 (19.7%) showed evidence of hyaline cartilage in the intraoperative specimens. Hyaline cartilage was more common in patients with MCs (P < 0.05). We found 2 cases of rLDH in the non-MC group (n = 71); 6 cases of rLDH were found in the MC group (n = 28), including 2 and 4 cases for types I and II, respectively. There was no significant difference between types I and II (P > 0.05). rLDH was more common in patients with MCs (P < 0.05). We found 5 rLDH cases in the hyaline cartilage group (n = 32); 3 rLDH cases were found in the nucleus pulposus group (n = 67). rLDH was more common in the hyaline cartilage group (P < 0.05). CONCLUSIONS: rLDH following PELD preferentially occurs when MCs or herniated cartilage are present.

Comparison of Percutaneous Transforaminal Endoscopic Discectomy with and without Epidural Steroid Application in the Treatment of Lumbar Disc Herniation: A Minimum of 2 Years of Follow-Up.

AIM: To compare the efficacy of percutaneous transforaminal endoscopic discectomy with and without epidural steroid application in the treatment of lumbar disc herniation. MATERIAL AND METHODS: A total of 101 patients who had indications for percutaneous transforaminal endoscopic discectomy were retrospectively reviewed. Patients were divided into two groups based on whether epidural steroids were applied following the surgical procedure. Each patient in group A received an epidural injection of 40mg triamcinolone acetonide through the working sleeve following the surgical procedure. However, patients in group B were not given the drug. Preoperative and postoperative radicular pain was measured with the visual analogue scale (VAS). Functional and satisfaction outcomes were measured with the Oswestry Disability Index (ODI) and the modified MacNab criteria, respectively. RESULTS: A total of 97 patients had a complete follow-up of longer than two years without recurrence. The sample sizes of group A and group B were 56 and 41. The VAS scores and ODI scores at each postoperative follow-up point were significantly lower than the preoperative values (p < 0.001). However, there were no significant between-group differences (p > 0.05). The secondary outcomes of the changes in the VAS and ODI scores were also equivalent between the groups at the 3-month and 2-year follow-ups (p > 0.05). No significant difference was observed in the modified MacNab criteria between the groups at 2 years (p=0.7715). CONCLUSION: Percutaneous transforaminal endoscopic discectomy is a safe and effective minimally invasive surgery for radiculopathy caused by lumbar disc herniation. Epidural steroid injection following the surgical procedure offered no benefit compared with surgery alone.

Early outcomes of transforaminal percutaneous endoscopic lumbar discectomy for high school athletes with herniated nucleus pulposus of the lumbar spine.

There are no reports in the literature on the clinical outcomes of percutaneous endoscopic lumbar discectomy (PELD) for high school athletes suffering from herniated nucleus pulposus (HNP) of the lumbar spine. PELD is a minimally invasive surgical procedure that can be performed under local anesthesia via an 8-mm skin incision. This study examined the outcomes of transforaminal PELD in high school athletes suffering from HNP. Subjects were 18 patients [14 males and four females; mean age 17 (15-18) years] who underwent PELD at our institutions. The events in which the patients competed were baseball (n = 6), softball (n = 2), rugby (n = 2), basketball (n = 2), table tennis (n = 2), American football (n = 1), wrestling (n = 1), track and field (n = 1), and dance (n = 1). All patients underwent PELD under local anesthesia. Back pain was assessed using the Japanese Orthopaedic Association Back Pain Evaluation Questionnaire (JOABPEQ) and a visual analog scale (VAS) before and after surgery. Time to return to competitive sport, complications, and rate of recurrence of herniation were examined. All factors assessed by the JOABPEQ were significantly improved after surgery. VAS score was also improved after surgery. Time to return to competitive sport was 7 weeks on average. The rate of return to play was 94.4%. There were no complications, such as dural tear, exiting nerve root injury, or hematoma. One patient had recurrence of HNP. PELD is a promising minimally invasive and effective procedure for high school athletes with HNP.

Effect of time to first ambulation on recurrence after PELD.

STUDY DESIGN: Retrospective cohort study. OBJECTIVE: To evaluate the effect of time to first ambulation on recurrence after percutaneous endoscopic lumbar discectomy (PELD). METHODS: From July 2017 to August 2018, 90 patients with lumbar intervertebral disc herniation underwent PELD surgery. According to the initial walking time, i.e., the time until the patient could walk after the operation, the operations were divided into three groups: early stage, middle stage, and late stage. The follow-up period was 3 months, and complete follow-up data were obtained. The visual analog scale (VAS) and Oswestry disability index (ODI) scores before the operation, at first ambulation, 1 month after the operation, and 3 months after the operation and the recurrence and incidence rates of high magnetic resonance imaging (MRI) signal in the vertebral endplate area were recorded after the operation. RESULTS: The success rate was 100% for these 90 cases. The VAS and ODI scores at the first ambulation after the operation significantly improved compared with those before the operation, and the difference was statistically significant. The improvements in the lumbar VAS and ODI scores of the middle- and late-stage groups were better than that of the early-stage group at 1 and 3 months after the operation, and the differences were statistically significant; however, there was no significant difference between the middle- and late-stage groups. The postoperative recurrence rate and rate of high MRI signal in the vertebral endplate area were significantly higher in the early-stage group than in the other two groups, and the difference was statistically significant. CONCLUSION: The time to first ambulation after PELD is an important factor affecting the curative effect of the operation. Early ambulation may be one of the factors affecting recurrence after PELD.

Percutaneous Transforaminal Endoscopic Discectomy Versus Microendoscopic Discectomy for Lumbar Disc Herniation: Two-Year Results of a Randomized Controlled Trial.

STUDY DESIGN: A prospective randomized controlled study. OBJECTIVE: To clarify whether percutaneous transforaminal endoscopic discectomy (PTED) has better clinical outcomes and less surgical trauma compared with microendoscopic discectomy (MED). SUMMARY OF BACKGROUND DATA: Two kinds of minimally invasive spine surgeries, PTED and MED, are now widely used for the treatment of lumbar disc herniation (LDH). It is still a controversial issue to choose the proper surgical approach. METHODS: In this single-center, open-label, randomized controlled trial, patients were included if they had persistent signs and symptoms of radiculopathy with corresponding imaging-confirmed LDH, and were randomly allocated to PTED or MED group. The primary outcome was the score of Oswestry Disability Index (ODI) and the secondary outcomes included the score of Medical Outcomes Study 36-Item Short-Form Health Survey bodily pain and physical function scales, European Quality of Life-5 Dimensions, and Visual Analogue Scales for back pain and leg pain. RESULTS: A total of 250 participants were randomly assigned to two treatment groups, 241 of that received the specific surgical procedure. Two hundred twenty-two patients (92.1%) have completed the 2-year follow-up. Both the primary and secondary outcomes did not differ significantly between the two treatment groups at each prespecified follow-up time (P > 0.05). For PTED, the postoperative improvement of ODI score in the median herniation subgroup was less compared with paramedian subgroup. For MED, less improvement of ODI score was found in far-lateral herniation subgroup compared with paramedian subgroup. Total complication rate over the course of 2 year was 13.44% in PTED group and 15.57% in MED group (P = 0.639). Ten cases (8.40%) in PTED group and five cases (4.10%) in MED group suffered from residue/recurrence of herniation, for which reoperation was required. CONCLUSION: Over the 2-year follow-up period, PTED did not show superior clinical outcomes and did not appear to be safer procedure for patients with LDH compared with MED. PTED had inferior results for median disc herniation, whereas MED did not appear to be the best option for far-lateral disc herniation. LEVEL OF EVIDENCE: 2.

Biomechanical role of osteoporosis affects the incidence of adjacent segment disease after percutaneous transforaminal endoscopic discectomy.

STUDY DESIGN: Variation in the biomechanical characteristics of intervertebral discs adjacent to the segment disc after undergoing percutaneous transforaminal endoscopic discectomy (PTED) in models with normal and abnormal bone mineral density (BMD) was estimated using the finite element method. OBJECTIVE: The study investigated the change in the incidence of adjacent segment disease (ASD) after PTED in patients without and with osteoporosis. BACKGROUNDS: PTED has been widely used for treating lumbar disc herniation (LDH); changes in BMD will affect biomechanical characteristics, possibly leading to changes in the incidence of ASD after PTED. However, this issue remains largely unclear. METHODS: A non-linear, lumbosacral finite element model was reconstructed based on imaging data and validated using compared values computed by the current model from published and well-validated, in vitro biomechanical experiment studies. Corresponding PTED models with normal and abnormal BMDs were also reconstructed. Shear and von Mises stresses on the annulus fibrosis, the von Mises stress on the endplates in L5-S1 segment discs, and the total deformation of current lumbosacral models were computed in different body positions by changing loading conditions, including flexion, extension, left and right lateral bending, and axial rotation. RESULTS: In most loading conditions, biomechanical characteristics of the lumbosacral segment discs with normal BMDs after PTED slightly increased. However, in the PTED model with osteoporosis, most of the biomechanical characteristics dramatically increased. CONCLUSION: Osteoporosis leads to the deterioration of biomechanical characteristics in the adjacent segment disc after PTED; this variation may also result in an increase in the incidence of ASD. However, further studies on the interactions between pathological changes are warranted.

The frequency of re-surgery after lumbar disc Nucleoplasty in a ten-year period.

OBJECTIVE: Percutaneous disc nucleoplasty (PDN) is a minimally invasive technique. A portion of the nucleus tissue is ablated using the Coblation technique. Re-surgery is an important factor for the clinical outcome. However, the rate of subsequent surgery after PDN is still unknown. The aim of the present study was to investigate the frequency of an additional open surgery after PDN in a retrospective of more than ten years. PATIENTS AND METHODS: Retrospective observational study. Consecutive patients who underwent PDN between 2005 and 2006 were included. Patient's satisfaction was evaluated using MacNab's outcome criteria. The patient data (age and gender), the MRI findings (annular fissure or contained herniation) and the follow-up time was evaluated. A distinction was made between patients with only lumbago and patients with radiating pain. The focus of this study was to evaluate the necessity of an additional surgery at the same level. The period of time between the PDN and re-surgery was analyzed. RESULTS: In total, 203 patients were included in this study. All patients were seen one month after PDN. The follow-up time was longer than five years in 41 patients (20.2%), and longer than 10 years in 16 patients (7.9%). The short-term success rate was 63.5%; however, 18.7% of all patients had to undergo an additional surgery at the index level. Half of these additional surgeries were performed during the first three months after PDN. If only a poor pain reduction was achieved, re-surgery was significantly more frequent compared to patients with substantial pain relief. An initial surgery at the L4-5 level was associated more often with an additional surgery compared to an initial surgery at the L5-S1 level. CONCLUSION: The present study is the first study to report the frequency of re-surgery after PDN. At first sight, the fact that 63.5% of patients are satisfied seems to be a good result. However, this short-term result was significantly worsened due to a re-surgery rate at the index level of 18.7%. Moreover, it is possible that nucleoplasty has adverse effects resulting from the puncture and progressive degeneration. Therefore, indications for nucleoplasty should be critically reconsidered.

The Recovery of Motor Strength after Posterior Percutaneous Endoscopic Cervical Foraminotomy and Discectomy.

OBJECTIVE: Cervical radiculopathy infrequently presents with motor weakness. Motor weakness was improved in >90% of patients after anterior cervical discectomy and fusion or posterior cervical foraminotomy. Posterior percutaneous endoscopic cervical foraminotomy and discectomy (PECF) is an alternative surgical technique, but the outcome of motor weakness has not been reported. Our objective was to demonstrate the longitudinal outcomes of motor weakness after PECF. METHODS: A retrospective review of 106 consecutive patients was performed. Preoperative motor weakness was graded as mild (IV/V strength) or severe (less than III/V strength). The patients visited the outpatient clinic at 1, 3, 6, and 12 months after surgery and yearly thereafter. Improvement was defined as an improved weakness of more than 1 grade, and normalization was defined as the recovery of complete motor strength. RESULTS: Motor weakness preoperatively presented in 76 of 106 (72%) patients (49%, mild weakness; 23%, severe weakness). After PECF, the weakness improved in 72 of 76 (95%) patients and normalized in 65 of 76 (86%) patients. In the patients with mild weakness, the normalization rates were 48%, 81%, 90%, and 96% at postoperative months 1, 3, 6, and 12, respectively. In the patients with severe weakness, the improvement rates were 50%, 71%, 83%, 88%, and 92%, and the normalization rates were 8%, 38%, 58%, 58%, and 63% at postoperative months 1, 3, 6, 12, and 24, respectively. CONCLUSIONS: Preoperative motor weakness was improved in 95% of the patients after PECF, but motor weakness was not normalized in 37% of the patients with severe weakness.

Operative Approaches for Lumbar Disc Herniation: A Systematic Review and Multiple Treatment Meta-Analysis of Conventional and Minimally Invasive Surgeries.

BACKGROUND: Minimally invasive surgery (MIS) techniques have emerged as viable and safe alternatives for lumbar disc herniation, including percutaneous discectomy, percutaneous endoscopic discectomy, and tubulardiscectomy (TD). We present here a systematic review and a multiple-treatment meta-analysis evaluating the operative outcomes and patient-reported outcomes of open/microdiscectomy (OD/MD) and all MIS approaches for lumbar disc herniation. METHODS: The PICO approach and PRISMA (i.e., Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines were followed to query existing online databases since their inception to 2016, which yielded 14 studies after we applied the inclusion/exclusion criteria. The Cochrane Collaboration's tool for assessing risk of bias in randomized trials was used to assess the risk of bias in each study was used to assess the risk of bias in each study. Each outcome was assessed across all studies with the GRADE (i.e., Grading of Recommendations, Assessment, Development and Evaluations) criteria. RESULTS: There were 1707 patients analyzed, with 782 (45.81%) undergoing OD/MD, 491 (28.76%) undergoing TD, 199 (11.65%) undergoing percutaneous endoscopic discectomy, and 235 (13.76%) patients undergoing percutaneous discectomy. TD was found to be associated with significantly worse Oswestry Disability Index scores (mean difference 1.17, P = 0.03) whereas OD/MD was associated with worse Oswestry Disability Index scores compared with all other approaches (mean difference 2.61, P = 0.03), significantly longer duration of stay (mean difference 2.96, P = 0.04), and more blood loss (mean difference 30.53, P < 0.001). In terms of complications, TD was found to be associated with a greater rate of overall complications (odds ratio [OR] 1.49, P = 0.002), greater incidence of dural tears (OR 1.72 P = 0.04), and recurrent herniation (OR 2.09, P = 0.0007). Finally, OD/MD was associated with significantly lower incidence of revision surgery (OR 0.53, P = 0.0007). CONCLUSIONS: Our meta-analysis revealed that tubular-discectomy and percutaneous-endoscopic-discectomy, the most commonly employed MIS techniques for discectomy, can be used as safe alternatives for open discectomy depending on the preference of the operating surgeon.

Percutaneous Transforaminal Endoscopic Discectomy for the Treatment of Lumbar Disc Herniation in Obese Patients: Health-Related Quality of Life Assessment in a 2-Year Follow-Up.

BACKGROUND: Percutaneous transforaminal endoscopic discectomy (PTED) is a minimally invasive surgical technique used principally for the treatment of lumbar disc herniation (LDH). LDH is a frequent spinal ailment in obese individuals. The aim of this prospectively designed study was to assess for the first time in the literature the impact of PTED in postoperative parameters of health-related quality of life (HRQoL) in obese patients with LDH within a 2-year follow-up period, to further evaluate the effectiveness of PTED. METHODS: Patients with surgically treatable LDH were divided into 2 groups. Group A constituted 20 obese patients, and group B was composed of 10 patients with normal body mass index (BMI). A visual analog scale was used for pain evaluation, and the Short Form SF-36 Medical Survey Questionnaire contributed to HRQoL assessment. Follow-up was conducted preoperatively and at 6 weeks and 3, 6, 12, and 24 months postoperatively. RESULTS: Two of the 20 patients (10%) presented with severe postoperative pain, necessitating conventional microdiscectomy. All studied parameters exhibited maximal improvement at 6 months in group A and at 6 weeks in group B, with subsequent stabilization. Obese patients scored lower in all parameters compared with their healthy counterparts with normal BMI, acquiring a less favorable clinical benefit. CONCLUSIONS: PTED appears to be a generally safe and effective method for treating obese patients with LDH. However, major technical challenges that lead to a higher frequency of complications, as well as the lesser acquired clinical benefit, in obese patients may contribute to the further consideration for PTED in specific obese patients, especially on the grounds of low surgical experience.

Increased Volume of Lumbar Surgeries for Herniated Intervertebral Disc Disease and Cost-Effectiveness Analysis: A Nationwide Cohort Study.

STUDY DESIGN: Retrospective cohort study of a nationwide database. OBJECTIVE: The primary objective was to summarize the use of surgical methods for lumbar herniated intervertebral disc disease (HIVD) at two different time periods under the national health insurance system. The secondary objective was to perform a cost-effectiveness analysis by utilizing incremental cost-effectiveness ratio (ICER). SUMMARY OF BACKGROUND DATA: The selection of surgical method for HIVD may or may not be consistent with cost effectiveness under national health insurance system, but this issue has rarely been analyzed. METHODS: The data of all patients who underwent surgeries for HIVD in 2003 (n = 17,997) and 2008 (n = 38,264) were retrieved. The surgical methods included open discectomy (OD), fusion surgery, laminectomy, and percutaneous endoscopic lumbar discectomy (PELD). The hospitals were classified as tertiary-referral hospitals (≥300 beds), medium-sized hospitals (30-300 beds), or clinics (<30 beds). ICER showed the difference in the mean total cost per 1% decrease in the reoperation probability among surgical methods. The total cost included the costs of the index surgery and the reoperation. RESULTS: In 2008, the number of surgeries increased by 2.13-fold. The number of hospitals increased by 34.75% (731 in 2003 and 985 in 2008). The proportion of medium-sized hospitals increased from 62.79% to 70.86%, but the proportion of surgeries performed at those hospitals increased from 61.31% to 85.08%. The probability of reoperation was highest after laminectomy (10.77%), followed by OD (10.50%), PELD (9.20%), and fusion surgery (7.56%). The ICERs indicated that PELD was a cost-effective surgical method. The proportion of OD increased from 71.21% to 84.12%, but that of PELD decreased from 16.68% to 4.57%. CONCLUSION: The choice of surgical method might not always be consistent with cost-effectiveness strategies, and a high proportion of medium-sized hospitals may be responsible for this change. LEVEL OF EVIDENCE: 4.

"Minimally invasive" lumbar spine surgery: a critical review.

BACKGROUND: Minimal-access technology has evolved rapidly with "tubular" or "percutaneous" approaches for decompression and stabilization in the lumbar spine. Potential benefits (smaller scars, diminished local pain, reduced blood loss, reduced postoperative wound pain, shorter hospital stays) have to be weighed against possible drawbacks (reduced orientation, steep learning curve, increased radiation exposure, dependency on technology, cost). While non-comparative case series are often rather enthusiastic, comparative studies and particularly RCTs are scarce and might convey a more realistic appreciation. METHODS: A MEDLINE search via PubMed was performed to find all English-language studies comparing "open" or "traditional" or "conventional" with "minimally invasive" or "percutaneous" or "tubular" approaches in degenerative lumbar spine surgery. RESULTS: Only nine comparative studies could be retrieved altogether. No clear benefit could be found for minimally invasive procedures in lumbar disc herniation, TLIF, or PLIF. There seems to be a slight advantage in terms of hardware safety in open procedures. CONCLUSIONS: This review, based solely on the very limited number of available comparative studies, shows no relevant benefit from minimally invasive techniques, and a tendency for more safety in open procedures in lumbar disc herniation, TLIF and PLIF.

Operative management of lumbar disc herniation : the evolution of knowledge and surgical techniques in the last century.

Removal of a herniated disc with the use of the operative microscope was first performed by Yasargil (Adv Neurosurg. 4:81-2, 1977) in 1977. However, it began to be used more and more only in the late 1980s (McCulloch JA (1989) Principles of microsurgery for lumbar disc disease. Raven Press, New York). In the 1990s, many spinal surgeons abandoned conventional discectomy with naked-eye to pass to the routine practice of microdiscectomy. The merits of this technique are that it allows every type of disc herniation to be excised through a short approach to skin, fascia and muscles as well as a limited laminoarthrectomy. For these reasons, it has been, and still is, considered the "gold standard" of surgical treatment for lumbar disc herniation, and the method used by the vast majority of spinal surgeons. In the 1990s, the advent of MRI and the progressive increase in definition of this modality of imaging, as well as histopathologic and immunochemical studies of disc tissue and the analysis of the results of conservative treatments have considerably contributed to the knowledge of the natural evolution of a herniated disc. It was shown that disc herniation may decrease in size or disappear in a few weeks or months. Since the second half of the 1990s there has been a revival of percutaneous procedures. Some of these are similar to the percutaneous automated nucleotomy; other methods are represented by intradiscal injection of a mixture of "oxygen-ozone" (Alexandre A, Buric J, Paradiso R. et al. (2001) Intradiscal injection of oxygen ozone for the treatment of lumbar disc herniations: result at 5 years. 12th World Congress of Neurosurgery; 284-7), or laserdiscectomy performed under CT scan (Menchetti PPM. (2006) Laser Med Sci. 4:25-7). The really emerging procedure is that using an endoscope inserted into the disc through the intervertebral foramen to visualize the herniation and remove it manually using thin pituitary rongeurs, a radiofrequency probe or both (Chiu JC. (2004) Surg Technol Int. 13:276-86).Microdiscectomy is still the standard method of treatment due to its simplicity, low rate of complications and high percentage of satisfactory results, which exceed 90% in the largest series. Endoscopic transforaminal discectomy appears to be a reliable method, able to give similar results to microdiscectomy, provided the surgeon is expert enough in the technique, which implies a long learning curve in order to perform the operation effectively, with no complications. All the non-endoscopic percutaneous procedures now available can be used, but the patient must be clearly informed that while the procedure is simple and rapid, at least for the disc L4-L5 and those above (except for laserdiscectomy under CT, that can be easily performed also at L5-S1), their success rate ranges from 60 to 70% and that, in many cases, pain may decrease slowly and may take even several weeks to disappear.

Percutaneous iliac screw placement: description of a new minimally invasive technique.

Minimally invasive spinal instrumentation techniques have evolved tremendously over the past decade. Although there have been numerous reports of lumbar instrumentation performed via a percutaneous or minimal incisional route, to date there have been no reports of minimally invasive iliac screw placement. A method was developed for accurate placement of minimally invasive iliac screw placement based on a modification of currently available percutaneous lumbar instrumentation techniques. The method involves fluoroscopically guided insertion of a cannula-based screw system, and this technique was successful applied to treat an L-5 burst fracture with L-4 to iliac spinal stabilization via a minimally invasive approach. This report demonstrates the feasibility of percutaneous iliac screw instrumentation. However, future studies will be needed to validate the safety and efficacy of this approach.

Nuances in percutaneous discectomy.

This article presents an update of the field of percutaneous discectomy and a perspective as to where percutaneous discectomy currently fits in the treatment of patients with herniated discs. The future of minimally invasive disc surgery is also entertained, and a novel approach to lumbar disc surgery is presented.