The evolution of minimally invasive spine surgery

Transforaminal Contrast Injection Before Computed Tomography-Guided Lateral Endoscopic Lumbar Diskectomy Improves Visualization of Exiting Nerve Root

BACKGROUND AND OBJECTIVES

Percutaneous endoscopic lumbar diskectomy (PELD) is an effective, minimally invasive method for removal of lateral lumbar disk herniations. This minimally invasive technique can be applied with high success and lead to faster recovery than traditional methods. Unfortunately, adoption of these techniques in the United States has been slow. A significant barrier to using this technique is often an inability to completely visualize relevant anatomy and increased operative times. In this article, we describe a technique using computed tomography (CT) guidance in conjunction with a neurogram to perform a PELD. We detail the steps in the technique and its advantages to the surgeon performing it.

METHODS

After a patient is placed supine on a table, a transforaminal injection of contrast is performed under fluoroscopic guidance. Then, after sterilizing and draping in a normal fashion, an intraoperative CT scan is taken with a reference frame in place. During the procedure, this allows for the CT guidance to have the exiting nerve root clearly outlined.

RESULTS

This procedure was successfully performed in a single patient, allowing greater visualization of the exiting nerve root during a difficult revision PELD case. No complications were experienced.

CONCLUSION

A novel technique using a neurogram with CT guidance during a PELD was used to assist with identification of anatomy and decompression of the exiting nerve root. This technique was used without complications.

PDS-MAR: a fine-grained projection-domain segmentation-based metal artifact reduction method for intraoperative CBCT images with guidewires

Objective.Since the invention of modern Computed Tomography (CT) systems, metal artifacts have been a persistent problem. Due to increased scattering, amplified noise, and limited-angle projection data collection, it is more difficult to suppress metal artifacts in cone-beam CT, limiting its use in human- and robot-assisted spine surgeries where metallic guidewires and screws are commonly used.Approach.To solve this problem, we present a fine-grained projection-domain segmentation-based metal artifact reduction (MAR) method termed PDS-MAR, in which metal traces are augmented and segmented in the projection domain before being inpainted using triangular interpolation. In addition, a metal reconstruction phase is proposed to restore metal areas in the image domain.Main results.The proposed method is tested on both digital phantom data and real scanned cone-beam computed tomography (CBCT) data. It achieves much-improved quantitative results in both metal segmentation and artifact reduction in our phantom study. The results on real scanned data also show the superiority of this method.Significance.The concept of projection-domain metal segmentation would advance MAR techniques in CBCT and has the potential to push forward the use of intraoperative CBCT in human-handed and robotic-assisted minimal invasive spine surgeries.

Advances and Evolving Challenges in Spinal Deformity Surgery

BACKGROUND

Surgical intervention is a critical tool to address adult spinal deformity (ASD). Given the evolution of spinal surgical techniques, we sought to characterize developments in ASD correction and barriers impacting clinical outcomes.

METHODS

We conducted a literature review utilizing PubMed, Embase, Web of Science, and Google Scholar to examine advances in ASD surgical correction and ongoing challenges from patient and clinician perspectives. ASD procedures were examined across pre-, intra-, and post-operative phases.

RESULTS

Several factors influence the effectiveness of ASD correction. Standardized radiographic parameters and three-dimensional modeling have been used to guide operative planning. Complex minimally invasive procedures, targeted corrections, and staged procedures can tailor surgical approaches while minimizing operative time. Further, improvements in osteotomy technique, intraoperative navigation, and enhanced hardware have increased patient safety. However, challenges remain. Variability in patient selection and deformity undercorrection have resulted in heterogenous clinical responses. Surgical complications, including blood loss, infection, hardware failure, proximal junction kyphosis/failure, and pseudarthroses, pose barriers. Although minimally invasive approaches are being utilized more often, clinical validation is needed.

CONCLUSIONS

The growing prevalence of ASD requires surgical solutions that can lead to sustained symptom resolution. Leveraging computational and imaging advances will be necessary as we seek to provide comprehensive treatment plans for patients.

Operative results of AO A3 and A4 traumatic injuries in the thoracic and lumbar spine. A multicenter surveillance study of 4230 patients from the German Spine Registry (DWG-Register)

BACKGROUND

The diagnosis, classification and treatment of thoracolumbar burst fractures, continue to be controversial. Surgery is generally the preferred treatment for unstable fractures while stable fractures are managed conservatively. This study aims to describe surgical procedures, outcomes, complications, demography, clinical features and differences between A3 and A4 fractures (AO classification) of the thoracolumbar region. A subgroup of patients <91 years with osteoporotic fractures is included and analyzed.

METHODS

Analysis of data from the DWG-Register German spine registry on operative treatment for thoracolumbar AO A3 and A4 fractures out of 170 departments from January 2017 to May 2021. The evaluated variables included age, gender, surgical approach (posterior, anterior combined), and re-operation.

RESULTS

In total, 4230 AO A3 and A4 thoracolumbar fractures were identified in the registry; 2898 A3 (group 1) and 1332 A4 (group 2). The preoperative ASIA-impairment scale score in group 1 was significantly different compared with group 2 (P=0.02). Surgical procedures such as decompression/stabilization with rod-screw system cemented/non-cemented, as well as an anterior approach, were statistically significant between the groups. Odds ratio was calculated for variables that could be influenced for the type of fracture (A3 or A4): decompression 4.89, OR time >2 hours 48.22, osteoporosis 6.46 and posterior access 9.85.

CONCLUSIONS

This study provides multicenter results from a huge number of surgically treated AO A3 and A4 fractures. Anterior approaches are more often used in A4 type fractures, probably because of its inherent instability related to burst fractures, surprisingly, not associated with the occurrence of added perioperative complications. Nevertheless, A3 type fractures are presented with worse ASIA Impairment-Scale at admission, in comparison with A4 type fractures of the thoracolumbar region.

A Beginner's Perspective on Biportal Endoscopic Spine Surgery in Single-Level Lumbar Decompression: A Comparative Study with a Microscopic Surgery

Background

The application of biportal endoscopic spinal surgery (BESS) in spine surgery is increasing. However, the clinical results of related studies have been inconsistent. In this study, the perioperative and clinical outcomes of two techniques in single-level lumbar decompression surgery were compared using the perspective of a spine surgeon experienced in microscopic surgery but inexperienced in BESS.

Methods

This is a retrospective study performed with prospectively collected data. From April 2019, 50 consecutive patients who underwent a single-level lumbar decompression surgery with BESS were evaluated. Additionally, the data of 150 consecutive patients who underwent the same microscopic surgery before April 2019 were collected. We performed 1 : 1 ratio propensity score matching for these two groups to adjust for baseline variables. The postoperative patient-reported outcome measures included the Oswestry Disability Index (ODI) and numeric rating scale for the back and leg preoperatively and at 6 months after surgery. The laboratory data (C-reactive protein [CRP, mg/L] and hemoglobin [Hb, g/dL]) were measured preoperatively and 3 times (1, 2, and 3 or 4 days) postoperatively. In these periods, the peak and lowest CRP and Hb concentrations were evaluated. The perioperative outcomes, operation time (from skin incision to dressing), length of hospital stay, drainage (for 24 hours after surgery), and surgery-related complications were also evaluated.

Results

Forty-seven patients (27 men and 20 women) were included in each group. The postoperative 6-month ODI was significantly lower in the BESS group than in the microscope group (6.90 ± 5.98 vs. 11.54 ± 9.70). The peak CRP concentration (16.63 ± 19.41 vs. 42.40 ± 37.73, p < 0.001) and CRP increment (peak CRP minus preoperative CRP, 14.69 ± 19.47 vs. 40.71 ± 37.32, p < 0.001) were significantly higher in the microscope group. Operation time (83.72 ± 35.71 vs. 70.27 ± 23.24, p = 0.047) was significantly longer in the BESS group. Surgery-related complications were found in 6 and 3 cases in the BESS group (3 revisions, 2 dural tears, and 1 conversion to open surgery) and microscope group (2 revisions and 1 hematoma), respectively.

Conclusions

BESS as a new technique resulted in satisfying short-term outcomes. It was a well-tolerated option for surgical treatment of single-level lumbar degenerative disease. The relatively high incidence of recurrence at the index level and incidental dural tears should be considered for surgeons new to BESS; however, these were manageable complications.

Learning curve for endoscopic posterior cervical foraminotomy

PURPOSE

While anterior cervical discectomy and fusion as well as cervical disk arthroplasty are gold standard treatments for the surgical treatment of cervical radiculopathy, posterior endoscopic cervical foraminotomy (PECF) as a substitute procedure is gaining popularity. To date, studies investigating the number of surgeries needed to achieve proficiency in this procedure are lacking. The purpose of the study is to examine the learning curve for PECF.

METHODS

The learning curve in operative time for two fellowship-trained spine surgeons at independent institutions was retrospectively assessed for 90 uniportal PECF procedures (PBD: n = 26, CPH: n = 64) performed from 2015 to 2022. Operative time was assessed across consecutive cases using a nonparametric monotone regression, and a plateau in operative time was used as a proxy to define the learning curve. Secondary outcomes assessing achievement of endoscopic prowess before and after the initial learning curve included number of fluoroscopy images, visual analog scale (VAS) for neck and arm, Neck Disability Index (NDI), and the need for reoperation.

RESULTS

There was no significant difference in operative time between surgeons (p = 0.420). The start of a plateau for Surgeon 1 occurred at 9 cases and 111.6 min. The start of a plateau for Surgeon 2 occurred at 29 cases and 114.7 min. A second plateau for Surgeon 2 occurred at 49 cases and 91.8 min. Fluoroscopy use did not significantly change before and after surmounting the learning curve. The majority of patients achieved minimally clinically important differences in VAS and NDI after PECF, but postoperative VAS and NDI did not significantly differ before and after achieving the learning curve. There were no significant differences in revisions or postoperative cervical injections before and after reaching a steady state in the learning curve.

CONCLUSION

PECF is an advanced endoscopic technique with an initial improvement in operative time that occurred after as few as 8 cases to as many as 28 cases in this series. A second learning curve may occur with additional cases. Patient-reported outcomes improve following surgery, and these outcomes are independent of the surgeon's position on the learning curve. Fluoroscopy use does not change significantly along the learning curve. PECF is a safe and effective technique that current and future spine surgeons should consider as part of their armamentarium.

Is navigation beneficial for transforaminal endoscopic lumbar foraminotomy? A preliminary comparison study with fluoroscopic guidance

PURPOSE

The primary purpose of this study was to determine radiation exposure of the surgeon during transforaminal endoscopic lumbar foraminotomy (TELF). Secondary purpose of this study was to compare clinical and radiologic outcomes between TELF under C-arm fluoroscopic guidance (C-TELF) and O-arm navigation-guided TELF (O-TELF).

METHODS

The author reviewed patients' medical records who underwent TELF at our institute from June 2015 to November 2022. A total of 40 patients were included (18 patients with C-TELF and 22 with O-TELF). Basic demographic data were collected. Preoperative/postoperative visual analog scale (VAS) and Oswestry Disability Index (ODI) were recorded at the outpatient clinic. Radiologic features were compared on X-rays at each follow-up. The degree of foraminal expansion was measured/compared through MRI. In the C-TELF group, the amount of exposure was calculated with a dosimeter.

RESULTS

Average surgeon's effective dose in the C-TELF group was 0.036 mSv. In the case of the O-TELF group, there was no radiation exposure during operation. However, the operation time in the O-TELF group was about 37 min longer than that in the C-TELF group. There were significant improvements in VAS/ODI after operation in both groups. Complications were identified in three patients.

CONCLUSION

O-TELF showed similarly favorable clinical and radiologic outcomes to C-TELF in lumbar foraminal stenosis, including complication rate. Compared to C-TELF, O-TELF has an advantage of not wearing a lead apron since the operator is not exposed to radiation. However, the operation time was longer with O-TELF due to O-arm setting time. Because there are pros and cons, the choice of surgical method depends on the surgeon's preference.

Background, techniques, applications, current trends, and future directions of minimally invasive endoscopic spine surgery: A review of literature

Across many of the surgical specialties, the use of minimally invasive techniques that utilize indirect visualization has been increasingly replacing traditional techniques which utilize direct visualization. Arthroscopic surgery of the appendicular skeleton has evolved dramatically and become an integral part of musculoskeletal surgery over the last several decades, allowing surgeons to achieve similar or better outcomes, while reducing cost and recovery time. However, to date, the axial skeleton, with its close proximity to critical neural and vascular structures, has not adopted endoscopic techniques at as rapid of a rate. Over the past decade, increased patient demand for less invasive spine surgery combined with surgeon desire to meet these demands has driven significant evolution and innovation in endoscopic spine surgery. In addition, there has been an enormous advancement in technologies that assist in navigation and automation that help surgeons circumvent limitations of direct visualization inherent to less invasive techniques. There are currently a multitude of endoscopic techniques and approaches that can be utilized in the treatment of spine disorders, many of which are evolving rapidly. Here we present a review of the field of endoscopic spine surgery, including the background, techniques, applications, current trends, and future directions, to help providers gain a better understanding of this growing modality in spine surgery.

Long-Term Reoperation Rates After Open versus Minimally Invasive Spine Surgery for Degenerative Lumbar Disease: Five Year Follow-Up of 2130 Patients

BACKGROUND

Minimally Invasive Spine Surgery (MISS) is a growing alternative to Open Spine Surgery (OSS). The preservation of musculature and minimization of iatrogenic injury is hypothesized to decrease the need for reoperation by preserving normal anatomy. Our objective is to compare the relative long-term reoperation rates after MISS and OSS for the treatment of degenerative disease of the lumbar spine.

METHODS

This retrospective analysis compares the long-term reoperation rates after MISS and OSS. Eligible patients were adults with a primary lumbar intervention carried out between 5/1/2004 and 1/31/2014 to allow for at least 5 years of follow up. Patients without sufficient descriptive metrics or follow-up data were excluded. The primary outcome was the rate of lumbar spine reoperation.

RESULTS

A total of 2130 patients met the inclusion criteria-1895 underwent OSS and 235 underwent MISS. On average and across all surgery types (decompression and decompression with fusion), 28% of OSS patients required reoperation during the minimum 5-year follow up period while only 14% of MISS patients required reoperation (P = 0.001). The MISS group was statistically identical to the OSS group in all categories except that the MISS group was on average 1.8 years older (62.25 vs. 60.45, P = 0.039) and had a higher incidence of diabetes (26% vs. 17%, P = 0.000), but had a lower average body mass index than the OSS group (28.35 vs. 29.60, P = 0.002).

CONCLUSIONS

In the setting of degenerative lumbar spine disease, MISS has the potential to reduce the long-term need for reoperation when compared with OSS.

Percutaneous Full Endoscopic Management of Spinal Foraminal Schwannomas: Case Series

BACKGROUND

Schwannoma, a benign peripheral nerve sheath tumor, is perhaps only secondary to degenerative pathology as the most common lesion at neural foramen. The surgical dilemma here is either risking nerve injury because of inadequate exposure or the need for internal fixation because of facet joint sacrifice.

OBJECTIVE

To evaluate the feasibility and safety of management of foraminal schwannomas by percutaneous full-endoscopic technique.

METHODS

A single-center retrospective review was conducted on patients who underwent full-endoscopic resection of neural foraminal schwannomas. Tumors were grouped into either medial type or lateral type based on relevant location to the neural foramen, and respective surgical approaches were adopted. Data including preoperative neurological status, tumor size, surgery time, the extension of resection, and clinical outcomes were collected. The learning curve was plotted as surgical time/tumor size against case number.

RESULTS

A total of 25 patients were treated between May 2015 and March 2022. Gross total resection was achieved in 24 patients, and near-total resection in 1 case, with 1 patient experienced transient voiding difficulty. No tumor recurrence or spinal instability was detected in the short-term follow-up (median follow-up 22 months, range 3 months-6 years). Surgical efficiency improved with the number of cases operated on and remained stable after the initial 10 cases.

CONCLUSION

Percutaneous full-endoscopic technique is a safe and minimally invasive technique for the resection of foraminal schwannomas.

Minimally Invasive Resection of Benign Osseous Tumors of the Spinal Column: 10 Years' Experience and Long-Term Outcomes of a Specialized Center

Background and Objectives: Benign osseous tumors of the spinal column comprise about 10% of all spinal tumors and are rare cause for surgery. However, these tumors pose various management challenges and conventional surgery may be associated with significant morbidity. Previous reports on minimally invasive resection of these lesions are rare. We report a series of patients managed by total resection of benign osseous spine tumors using MIS techniques. Surgical decisions and technical considerations are discussed. Materials and Methods: A retrospective evaluation of prospectively collected data of patients who underwent minimally invasive surgery for removal of benign osseous vertebral tumors. Demographic, clinical and radiographic features, operative details and final pathological reports were summarized. Primary outcomes were completeness of tumor resection and pain relief assessed by VAS for back and leg pain. Secondary outcome measures were recurrence of tumor on repeat post-operative MRI and postoperative unstable deformity on standing scoliosis X-rays. Results: This series included 32 cases of primary osseous spine tumors resected by minimally invasive techniques. There were 17 males and 15 females aged 5-68 years (mean 23.3). The follow-up period was 8-90 months (mean 32 months) and the preoperative symptoms duration was 9-96 months. Axial spinal pain was the presenting symptom in all the patients. Five patients also complained about radicular pain and four patients had antalgic scoliosis. The tumor involved the thoracic spine in 12 cases, the lumbar segment in 11, the cervical in 5 and the sacral area in 4 cases. Complete tumor removal was performed in all patients. No procedure-related complications were encountered. Histopathology showed osteoid osteoma in 24 patients, osteoblastoma in 5 patients, and fibrous dysplasia, fibroadenoma and eosinophilic granuloma in one case each. All patients experienced significant pain relief after surgery, and had stopped pain medications by 12 months postoperatively. No patient suffered from tumor recurrence or spinal deformity. Conclusions: Minimally invasive surgery is feasible for total removal of selected benign vertebral tumors and may have some advantages over conventional surgical techniques.

[Brief history, global trends, and Chinese mission of unilateral biportal endoscopy technique]

The current unilateral biportal endoscopy (UBE) technique was originated from Argentina and developed in South Korea, which was rapidly growing and popularizing in China. The adoption of spinal endoscopy, using small cameras placed inside body with continuous water irrigation, providing better surgical field with less tissue dissection and quicker recovery for patients. As with other disciplines, the use of spinal endoscopy in spinal surgery will become increasingly widespread. UBE technique will promote the popularization of spinal endoscopy in China with monoportal endoscopy technique. At the same time, biportal endoscopy has better expansibility, the application of accessory incision may provide solution for more complicated spinal disease. Chinese spine surgeon should better understand the trends in spinal endoscopy, seize the opportunity of the rapidly evolving in spinal healthcare, and to promote the popularization of UBE across the globe.

Endoscope-Assisted Retroperitoneal Prepsoas Approach to Lumbar Intervertebral Disk Decompression. Technical Note

BACKGROUND

Increasingly there is an impetus on the part of surgeons to find more minimally invasive approaches to treat spinal pathologies. Retroperitoneal prepsoas and transpsoas approaches to the lumbar spine are one such example gaining increased attention. Endoscope-assisted approaches may help further reduce soft tissue dissection.

OBJECTIVE

To describe an endoscope-assisted lateral retroperitoneal prepsoas approach for lumbar diskectomy.

METHODS

Two fresh-frozen thoracolumbar cadaveric specimens were obtained and placed in the right lateral decubitus position. Using a left-sided, retroperitoneal prepsoas approach to the lumbar spine and under endoscopic visualization, diskectomies were performed at the L2/3, L3/4, L4/5, and L5/S1 intervertebral spaces. Qualitative assessment of the extent of central and contralateral foraminal decompression was performed.

RESULTS

The endoscope was found to provide effective visualization at all disk spaces and combined with the anterior retroperitoneal prepsoas approach allowed for effective decompression of all explored disk spaces. Both operators noted difficulty obtaining visualization of the ipsilateral foramen, but adequate central and contralateral foraminal decompression was achievable for central, paracentral, and contralateral far lateral disk protrusions.

CONCLUSION

Endoscope assistance may improve visualization of the lumbar intervertebral disk spaces during retroperitoneal prepsoas approaches and thereby help to expand the surgical indication for anterior and oblique lumbar interbody fusion.

Clinical experience on intertransverse extraforaminal approach for far lateral disc herniations: 132 cases

Background

Far lateral disc herniations attract many spine surgeons for their type of onset, degree of pain, risk of neurological deficit, and increasing incidence. Today, a direct approach to the region by miminally invasive techniques is preferred.

Aims

We aimed to present the results of the cases that were operated via intertransverse extraforaminal approach through a midline incision.

Patients and Methods

One hundred thirty-two patients who were operated for far lateral disc herniation by extraforaminal approach between January 2010 and December 2017 were retrospectively evaluated. The demographical data, level of disc herniations, examination findings, preoperative and postoperative VAS scores, and postoperative long-term MacNab satisfaction rates were recorded.

Results

Sixty-nine of the patients were male. The mean age was 58.1 years. Acute onset pain was a dominant complaint in 75% of the cases. The mean preoperative VAS score of 8.24 decreased to 2.08 at one month postoperatively. Based on a mean follow-up of 34.4 months, the long-term satisfaction rates according to Macnab criteria were 74% excellent-good, 20% moderate, and 6% poor.

Conclusion

Intertransverse extraforaminal approach is an effective and safe technique for far lateral disc herniations. However, considering the anatomical restrictions and the unfamiliarity of the surgeons with the region, it is important that the surgeons perform the surgery with the technique they know best to increase the success of the surgery.

Spinal endoscopy: evidence, techniques, global trends, and future projections

The utilization of indirect visualization during procedures has been increasingly replacing traditional forms of direct visualization across many different surgical specialties. The adoption of arthroscopy, using small cameras placed inside joints, has transformed musculoskeletal care over the last several decades, allowing surgeons to provide the same anatomic solutions with less tissue dissection, resulting in lower requirements for inpatient care, reduced costs, and expedited recovery.  For a variety of reasons, spine surgery has lagged behind other specialties in the adoption of indirect visualization.  Nonetheless, patient demand for less invasive spine procedures and surgeon drive to provide these solutions and improve care quality has driven global adoption of spinal endoscopy.  There are numerous endoscopic platforms and techniques currently utilized, and these systems are rapidly evolving.  Additionally, the variance in technology and health system incentives across the globe has generated tremendous regional heterogeneity in the utilization of spinal endoscopic procedures.  We present a consolidated review, including the background, evidence, techniques, and trends in spinal endoscopy, so that clinicians can gain a deeper understanding of this rapidly evolving domain of spinal healthcare.

An updated management algorithm for incorporating minimally invasive techniques to treat thoracolumbar trauma

OBJECTIVE

Minimally invasive surgery (MIS) techniques can effectively stabilize and decompress many thoracolumbar injuries with decreased morbidity and tissue destruction compared with open approaches. Nonetheless, there is limited direction regarding the breadth and limitations of MIS techniques for thoracolumbar injuries. Consequently, the objectives of this study were to 1) identify the range of current practice patterns for thoracolumbar trauma and 2) integrate expert opinion and literature review to develop an updated treatment algorithm.

METHODS

A survey describing 10 clinical cases with a range of thoracolumbar injuries was sent to 12 surgeons with expertise in spine trauma. The survey results were summarized using descriptive statistics, along with the Fleiss kappa statistic of interrater agreement. To develop an updated treatment algorithm, the authors used a modified Delphi technique that incorporated a literature review, the survey results, and iterative feedback from a group of 14 spine trauma experts. The final algorithm represented the consensus opinion of that expert group.

RESULTS

Eleven of 12 surgeons contacted completed the case survey, including 8 (73%) neurosurgeons and 3 (27%) orthopedic surgeons. For the 4 cases involving patients with neurological deficits, nearly all respondents recommended decompression and fusion, and the proportion recommending open surgery ranged from 55% to 100% by case. Recommendations for the remaining cases were heterogeneous. Among the neurologically intact patients, MIS techniques were typically recommended more often than open techniques. The overall interrater agreement in recommendations was 0.23, indicating fair agreement. Considering both literature review and expert opinion, the updated algorithm indicated that MIS techniques could be used to treat most thoracolumbar injuries. Among neurologically intact patients, percutaneous instrumentation without arthrodesis was recommended for those with AO Spine Thoracolumbar Classification System subtype A3/A4 (Thoracolumbar Injury Classification and Severity Score [TLICS] 4) injuries, but MIS posterior arthrodesis was recommended for most patients with AO Spine subtype B2/B3 (TLICS > 4) injuries. Depending on vertebral body integrity, anterolateral corpectomy or mini-open decompression could be used for patients with neurological deficits.

CONCLUSIONS

Spine trauma experts endorsed a range of strategies for treating thoracolumbar injuries but felt that MIS techniques were an option for most patients. The updated treatment algorithm may provide a foundation for surgeons interested in safe approaches for using MIS techniques to treat thoracolumbar trauma.

Decompression of Lumbar Central Spinal Canal Stenosis Following Minimally Invasive Transforaminal Lumbar Interbody Fusion

STUDY DESIGN

This was a retrospective clinical series.

OBJECTIVE

The objective of this study was to evaluate radiologic changes in central spinal canal dimensions following minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF) with placement of a static or an expandable interbody device.

SUMMARY OF BACKGROUND DATA

MIS-TLIF is used to treat lumbar degenerative diseases and low-grade spondylolisthesis. MIS-TLIF enables direct and indirect decompression of lumbar spinal stenosis, with patients experiencing relief from radiculopathy and neurogenic claudication. However, the effects of MIS-TLIF on the central spinal canal are not well-characterized.

MATERIALS AND METHODS

We identified patients who underwent MIS-TLIF for degenerative lumbar spondylolisthesis and concurrent moderate to severe spinal stenosis. We selected patients who had both preoperative and postoperative magnetic resonance imaging (MRI) and upright lateral radiographs of the lumbar spine. Measurements on axial T2-weighted MRI scans include anteroposterior and transverse dimensions of the dural sac and osseous spinal canal. Measurements on radiographs include disk height, neural foraminal height, segmental lordosis, and spondylolisthesis. We made pairwise comparisons between each of the central canal dimensions and lumbar sagittal segmental radiologic outcome measures relative to their corresponding preoperative values. Correlation coefficients were used to quantify the association between changes in lumbar sagittal segmental parameters relative to changes in radiologic outcomes of central canal dimensions. Statistical analysis was performed for "all patients" and further stratified by interbody device subgroups (static and expandable).

RESULTS

Fifty-one patients (age 60.4 y, 68.6% female) who underwent MIS-TLIF at 55 levels (65.5% at L4-L5) were included in the analysis. Expandable interbody devices were used in 45/55 (81.8%) levels. Mean duration from surgery to postoperative MRI scan was 16.5 months (SD 11.9). MIS-TLIF was associated with significant improvements in dural sac dimensions (anteroposterior +0.31 cm, transverse +0.38 cm) and osseous spinal canal dimensions (anteroposterior +0.16 cm, transverse +0.32 cm). Sagittal lumbar segmental parameters of disk height (+0.56 cm), neural foraminal height (+0.35 cm), segmental lordosis (+4.26 degrees), and spondylolisthesis (-7.5%) were also improved following MIS-TLIF. We did not find meaningful associations between the changes in central canal dimensions relative to the corresponding changes in any of the sagittal lumbar segmental parameters. Stratified analysis by interbody device type (static and expandable) revealed similar within-group changes as in the overall cohort and minimal between-group differences.

CONCLUSIONS

MIS-TLIF is associated with radiologic decompression of neural foraminal and central spinal canal stenosis. The mechanism for neural foraminal and central canal decompression is likely driven by a combination of direct and indirect corrective techniques.

A novel vertebral trench technique (VTT) involving transforaminal endoscopic lumbar foraminotomy (TELF) for very highly up-migrated lumbar disc herniation above L5

BACKGROUND

Percutaneous endoscopic lumbar discectomy (PELD) has become popular for the treatment of symptomatic lumbar disc herniation (LDH). The very highly up-migrated lumbar disc herniation (VHUM-LDH) is difficult to remove under PELD. The purpose of this research is to investigate the feasibility, clinical efficacy and operative nuances of a novel VTT involving TELF for this type of herniation.

METHODS

Eleven patients with very highly up-migrated LDH who underwent VTT involving TELF discectomy from May 2016 to May 2019 were included in this study. The operative time, length of hospital stay, and postoperative complications were recorded. Pre-and postoperative radiologic findings were investigated. All the patients were followed more than 1 year. The visual analogue score (VAS), Oswestry Disability Index (ODI), Japanese Orthopaedic Association (JOA) scores and modified MacNab criteria were used to assess surgical efficacy.

RESULTS

All the 11 patients underwent successful surgery. We compared the VAS, ODI, and JOA scores before and after surgery. The differences were statistically significant (P < 0.05). According to the modified MacNab criteria, 10 patients were assessed as "excellent", 1 patient was assessed as "good" at the last follow up.

CONCLUSION

The novel VTT involving TELF discectomy is a supplement to the traditional PELD. This technique enables the endoscope with working cannula to get closer the sequestrated nucleus pulposus without irritating the exiting nerve root, and facilitates the nucleus pulposus be removed successfully under direct visualization. The VTT involving TELF discectomy can be a safe, effective and feasible surgical procedure for the treatment of LDH with very highly up-migrated.

Multi-view 3D skin feature recognition and localization for patient tracking in spinal surgery applications

BACKGROUND

Minimally invasive spine surgery is dependent on accurate navigation. Computer-assisted navigation is increasingly used in minimally invasive surgery (MIS), but current solutions require the use of reference markers in the surgical field for both patient and instruments tracking.

PURPOSE

To improve reliability and facilitate clinical workflow, this study proposes a new marker-free tracking framework based on skin feature recognition.

METHODS

Maximally Stable Extremal Regions (MSER) and Speeded Up Robust Feature (SURF) algorithms are applied for skin feature detection. The proposed tracking framework is based on a multi-camera setup for obtaining multi-view acquisitions of the surgical area. Features can then be accurately detected using MSER and SURF and afterward localized by triangulation. The triangulation error is used for assessing the localization quality in 3D.

RESULTS

The framework was tested on a cadaver dataset and in eight clinical cases. The detected features for the entire patient datasets were found to have an overall triangulation error of 0.207 mm for MSER and 0.204 mm for SURF. The localization accuracy was compared to a system with conventional markers, serving as a ground truth. An average accuracy of 0.627 and 0.622 mm was achieved for MSER and SURF, respectively.

CONCLUSIONS

This study demonstrates that skin feature localization for patient tracking in a surgical setting is feasible. The technology shows promising results in terms of detected features and localization accuracy. In the future, the framework may be further improved by exploiting extended feature processing using modern optical imaging techniques for clinical applications where patient tracking is crucial.

Transfacet Minimally Invasive Transforaminal Lumbar Interbody Fusion With an Expandable Interbody Device-Part I: 2-Dimensional Operative Video and Technical Report

BACKGROUND

Advances in operative techniques and minimally invasive technologies have evolved to maximize patient outcomes and radiographic results, while reducing morbidity and recovery time.

OBJECTIVE

To describe the operative technique for a transfacet minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF) as a proposed modification to the standard approach MIS-TLIF.

METHODS

We present the case of a 72-yr-old man with left-sided lumbar radiculopathy. Preoperative imaging demonstrated degenerative lumbar anterolisthesis at L4-5, with associated canal and neuroforaminal stenosis. The patient underwent transfacet MIS-TLIF at L4-L5. We describe the preoperative planning, patient positioning, incision and dissection, pedicle screw insertion, transfacet approach to the working access corridor, discectomy, interbody device placement, fixation, and closure.

RESULTS

The transfacet MIS-TLIF utilizes 3 key techniques to safely maximize surgical correction: (1) a limited bony resection based on the superior articular process, leaving the medial inferior articular process, lateral superior articular process, and rostral pars intact, providing a working bony corridor that protects the traversing and exiting nerve roots; (2) decortication and release of the contralateral facet joint to provide additional capacity for indirect decompression and provide the first point of osseous fusion; and (3) placement of an expandable interbody device that provides additional indirect decompression to the working side and contralateral foramen.

CONCLUSION

The transfacet MIS-TLIF uniquely leverages a bony working corridor to access the disc space for discectomy and interbody placement. Transfacet MIS-TLIF is a feasible solution for lumbar spinal reconstruction to maximize direct and indirect decompression of the neuroforamina and central spinal canal in patients with lumbar degenerative diseases and low-grade spondylolisthesis.

Transfacet Minimally Invasive Transforaminal Lumbar Interbody Fusion With an Expandable Interbody Device-Part II: Consecutive Case Series

BACKGROUND

Advances in operative techniques and instrumentation technology have evolved to maximize patient outcomes following minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF). The transfacet MIS-TLIF is a modified approach to the standard MIS-TLIF that leverages a bony working corridor to access the disc space for discectomy and interbody device placement.

OBJECTIVE

To evaluate clinical and radiographic results following transfacet MIS-TLIF using an expandable interbody device.

METHODS

We performed a retrospective review of consecutive patients who underwent transfacet MIS-TLIF for degenerative lumbar spondylolisthesis. Patient-reported outcome measures for pain and disability were assessed. Sagittal lumbar segmental parameters and regional lumbopelvic parameters were assessed on upright lateral radiographs obtained preoperatively and during follow-up.

RESULTS

A total of 68 patients (61.8% male) underwent transfacet MIS-TLIF at 74 levels. The mean age was 63.4 yr and the mean follow-up 15.2 mo. Patients experienced significant short- and long-term postoperative improvements on the numeric rating scale for low back pain (-2.3/10) and Oswestry Disability Index (-12.0/50). Transfacet MIS-TLIF was associated with an immediate and sustained reduction of spondylolisthesis, and an increase in index-level disc height (+0.71 cm), foraminal height (+0.28 cm), and segmental lordosis (+6.83°). Patients with preoperative hypolordosis (<40°) experienced significant increases in segmental (+9.10°) and overall lumbar lordosis (+8.65°). Pelvic parameters were not significantly changed, regardless of preoperative alignment. Device subsidence was observed in 6/74 (8.1%) levels, and fusion in 50/53 (94.3%) levels after 12 mo.

CONCLUSION

Transfacet MIS-TLIF was associated with clinical improvements and restoration of radiographic sagittal segmental parameters. Regional alignment correction was observed among patients with hypolordosis at baseline.

Minimally Invasive Spine Surgery: Techniques, Technologies, and Indications

Over the past few decades, interest in minimally invasive spine surgery (MISS) has increased tremendously due to its core principle of minimizing approach-related injury while providing outcomes similar to traditional open spine procedures. With technical and technological advancements, MISS has expanded its utility not only to simple spinal stenosis, but also to complex spinal pathologies such as metastasis, trauma, or adult spinal deformity. In this article, we review the techniques and technology in MISS and discuss the indications, benefits, and limitations of MISS.

Design and control of an image-guided robot for spine surgery in a hybrid OR

BACKGROUND

Minimally invasive spine (MIS) fusion surgery requires image guidance and expert manual dexterity for a successful, efficient, and accurate pedicle screw placement. Operating room (OR)-integrated robotic solution can provide precise assistance to potentially minimize complication rates and facilitate difficult MIS procedures.

METHODS

A 5-degrees of freedom robot was designed specifically for a hybrid OR with integrated surgical navigation for guiding pedicle screw pilot holes. The system automatically aligns an instrument following the surgical plan using only instrument tracking feedback. Contrary to commercially available robotic systems, no tracking markers on the robotic arm are required. The system was evaluated in a cadaver study.

RESULTS

The mean targeting error (N = 34) was 1.27±0.57 mm and 1.62±0.85°, with 100% of insertions graded as clinically acceptable.

CONCLUSIONS

A fully integrated robotic guidance system, including intra-op imaging, planning, and physical guidance with optimized robot design and control, can improve workflow and provide pedicle screw guidance with less than 2 mm targeting error.

Feasibility and accuracy of a robotic guidance system for navigated spine surgery in a hybrid operating room: a cadaver study

The combination of navigation and robotics in spine surgery has the potential to accurately identify and maintain bone entry position and planned trajectory. The goal of this study was to examine the feasibility, accuracy and efficacy of a new robot-guided system for semi-automated, minimally invasive, pedicle screw placement. A custom robotic arm was integrated into a hybrid operating room (OR) equipped with an augmented reality surgical navigation system (ARSN). The robot was mounted on the OR-table and used to assist in placing Jamshidi needles in 113 pedicles in four cadavers. The ARSN system was used for planning screw paths and directing the robot. The robot arm autonomously aligned with the planned screw trajectory, and the surgeon inserted the Jamshidi needle into the pedicle. Accuracy measurements were performed on verification cone beam computed tomographies with the planned paths superimposed. To provide a clinical grading according to the Gertzbein scale, pedicle screw diameters were simulated on the placed Jamshidi needles. A technical accuracy at bone entry point of 0.48 ± 0.44 mm and 0.68 ± 0.58 mm was achieved in the axial and sagittal views, respectively. The corresponding angular errors were 0.94 ± 0.83° and 0.87 ± 0.82°. The accuracy was statistically superior (p < 0.001) to ARSN without robotic assistance. Simulated pedicle screw grading resulted in a clinical accuracy of 100%. This study demonstrates that the use of a semi-automated surgical robot for pedicle screw placement provides an accuracy well above what is clinically acceptable.