Retrospective single-surgeon study of prone versus lateral robotic pedicle screw placement: a CT-based assessment of accuracy

J Neurosurg Spine 39:490–497, 2023

Lateral lumbar interbody fusion including anterior-to-psoas oblique lumbar interbody fusion has conventionally relied on pedicle screw placement (PSP) for construct stabilization. Single-position surgery with lumbar interbody fusion in the lateral decubitus position with concomitant PSP has been associated with increased operative efficiency. What remains unclear is the accuracy of PSP with robotic guidance when compared with the more familiar prone patient positioning. The present study aimed to compare robot-assisted screw placement accuracy between patients with instrumentation placed in the prone and lateral positions.

METHODS The authors identified all consecutive patients treated with interbody fusion and PSP in the prone or lateral position by a single surgeon between January 2019 and October 2022. All pedicle screws placed were analyzed using CT scans to determine appropriate positioning according to the Gertzbein-Robbins classification grading system (grade C or worse was considered as a radiographically significant breach). Multivariate logistic regression models were constructed to identify risk factors for the occurrence of a radiographically significant breach.

RESULTS Eighty-nine consecutive patients (690 screws) were included, of whom 46 (477 screws) were treated in the prone position and 43 (213 screws) in the lateral decubitus position. There were fewer breaches in the prone (n = 13, 2.7%) than the lateral decubitus (n = 15, 7.0%) group (p = 0.012). Nine (1.9%) radiographically significant breaches occurred in the prone group compared with 10 (4.7%) in the lateral decubitus group (p = 0.019), for a prone versus lateral decubitus PSP accuracy rate of 98.1% versus 95.3%. There were no significant differences in BMI between prone versus lateral decubitus cohorts (30.1 vs 29.6) or patients with screw breach versus those without (31.2 vs 29.5). In multivariate models, the prone position was the only significant protective factor for screw accuracy; no other significant risk factors for screw breach were identified.

CONCLUSIONS The present data suggest that pedicle screws placed with robotic assistance have higher placement accuracy in the prone position. Further studies will be needed to validate the accuracy of PSP in the lateral position as single-position surgery becomes more commonplace in the treatment of spinal disorders.

Anterolateral versus posterior minimally invasive lumbar interbody fusion surgery for spondylolisthesis: comparison of outcomes from a global, multicenter study at 12-months follow-up

The Spine Journal 23 (2023) 1494−1505

Several minimally invasive lumbar interbody fusion techniques may be used as a treatment for spondylolisthesis to alleviate back and leg pain, improve function and provide stability to the spine. Surgeons may choose an anterolateral or posterior approach for the surgery however, there remains a lack of real-world evidence from comparative, prospective studies on effectiveness and safety with relatively large, geographically diverse samples and involving multiple surgical approaches.

PURPOSE: To test the hypothesis that anterolateral and posterior minimally invasive approaches are equally effective in treating patients with spondylolisthesis affecting one or two segments at 3months follow-up and to report and compare patient reported outcomes and safety profiles between patients at 12-months post-surgery.

DESIGN: Prospective, multicenter, international, observational cohort study.

PATIENT SAMPLE: Patients with degenerative or isthmic spondylolisthesis who underwent 1- or 2-level minimally invasive lumbar interbody fusion.

OUTCOME MEASURES: Patient reported outcomes assessing disability (ODI), back pain (VAS), leg pain (VAS) and quality of life (EuroQol 5D-3L) at 4-weeks, 3-months and 12-months follow-up; adverse events up to 12-months; and fusion status at 12-months post-surgery using X-ray and/or CT-scan. The primary study outcome is improvement in ODI score at 3-months. METHODS: Eligible patients from 26 sites across Europe, Latin America and Asia were consecutively enrolled. Surgeons with experience in minimally invasive lumbar interbody fusion procedures used, according to clinical judgement, either an anterolateral (ie, ALIF, DLIF, OLIF) or posterior (MIDLF, PLIF, TLIF) approach. Mean improvement in disability (ODI) was compared between groups using ANCOVA with baseline ODI score used as a covariate. Paired t-tests were used to examine change from baseline in PRO for both surgical approaches at each timepoint after surgery. A secondary ANCOVA using a propensity score as a covariate was used to test the robustness of conclusions drawn from the between group comparison.

RESULTS: Participants receiving an anterolateral approach (n=114) compared to those receiving a posterior approach (n=112) were younger (56.9 vs 62.0 years, p <.001), more likely to be employed (49.1% vs 25.0%, p<.001), have isthmic spondylolisthesis (38.6% vs 16.1%, p<.001) and less likely to only have central or lateral recess stenosis (44.9% vs 68.4%, p=.004). There were no statistically significant differences between the groups for gender, BMI, tobacco use, duration of conservative care, grade of spondylolisthesis, or the presence of stenosis. At 3-months follow-up there was no difference in the amount of improvement in ODI between the anterolateral and posterior groups (23.2 § 21.3 vs 25.8 § 19.5, p=.521). There were no clinically meaningful differences between the groups on mean improvement for back- and leg-pain, disability, or quality of life until the 12-months follow-up. Fusion rates of those assessed (n=158; 70% of the sample), were equivalent between groups (anterolateral, 72/88 [81.8%] fused vs posterior, 61/70 [87.1%] fused; p=.390).

CONCLUSIONS: Patients with degenerative lumbar disease and spondylolisthesis who underwent minimally invasive lumbar interbody fusion presented statistically significant and clinically meaningful improvements from baseline up to 12-months follow-up. There were no clinically relevant differences between patients operated on using an anterolateral or posterior approach.

Far lateral lumbar interbody fusion with unilateral pedicle screw fixation and double traversing cages using a biportal endoscopic technique

Acta Neurochirurgica (2023) 165:2165–2169

Transforaminal lumbar interbody fusion (TLIF) with a single cage and bilateral pedicle screw fixation results in decreased stability or increased risk of cage displacement Wang and Guo (Comput Methods Biomech Biomed Eng, 24(3):308–319, 6). We succeeded in inserting double traversing cages with unilateral pedicle screw fixation (UPSF) during far lateral TLIF using unilateral biportal endoscopy (UBE).

Method We attempted far lateral UBE-TLIF through two small incisions for degenerative lumbar spondylolisthesis with unilateral stenosis. With the help of novel instruments, far lateral UBE-TLIF with double traversing cages and UPSF was performed under tracheal intubation anaesthesia.

Conclusions We successfully performed far lateral UBE-TLIF with double traversing cages and UPSF. This procedure may be an alternative minimally invasive method for treating lumbar instability.

Transforaminal lumbar interbody fusion (TLIF) versus posterolateral instrumented fusion (PLF) in degenerative lumbar disorders

Eur Spine J (2013) 22:2022–2029

The aim of the present study was to analyze outcome, with respect to functional disability, pain, fusion rate, and complications of patients treated with transforaminal lumbar interbody fusion (TLIF) in compared to instrumented poserolateral fusion (PLF) alone, in low back pain. Spinal fusion has become a major procedure worldwide. However, conflicting results exist. Theoretical circumferential fusion could improve functional outcome. However, the theoretical advantages lack scientific documentation.

Methods Prospective randomized clinical study with a 2-year follow-up period. From November 2003 to November 2008, 100 patients with severe low back pain and radicular pain were randomly selected for either posterolateral lumbar fusion [titanium TSRH (Medtronic)] or transforaminal lumbar interbody fusion [titanium TSRH (Medtronic)] with anterior intervertebral support by tantalum cage (Implex/Zimmer). The primary outcome scores were obtained using Dallas Pain Questionnaire (DPQ), Oswestry disability Index, SF-36, and low back pain Rating Scale. All measures assessed the endpoints at 2-year follow-up after surgery.

Results The overall follow-up rate was 94 %. Sex ratio was 40/58. 51 patients had TLIF, 47 PLF. Mean age 49(TLIF)/45(PLF). No statistic difference in outcome between groups could be detected concerning daily activity, work leisure, anxiety/depression or social interest. We found no statistic difference concerning back pain or leg  pain. In both the TLIF and the PLF groups the patients had significant improvement in functional outcome, back pain, and leg pain compared to preoperatively. Operation time and blood loss in the TLIF group were significantly higher than in the PLF group (p \ 0.001). No statistic difference in fusion rates was detected.

Conclusions Transforaminal interbody fusion did not improve functional outcome in patients compared to posterolateral fusion. Both groups improved significantly in all categories compared to preoperatively. Operation time and blood loss were significantly higher in the TLIF group.

Patient outcomes after circumferential minimally invasive surgery compared with those of open correction for adult spinal deformity

J Neurosurg Spine 36:203–214, 2022

Circumferential minimally invasive spine surgery (cMIS) for adult scoliosis has become more advanced and powerful, but direct comparison with traditional open correction using prospectively collected data is limited. The authors performed a retrospective review of prospectively collected, multicenter adult spinal deformity data. The authors directly compared cMIS for adult scoliosis with open correction in propensity-matched cohorts using health-related quality-of-life (HRQOL) measures and surgical parameters.

METHODS Data from a prospective, multicenter adult spinal deformity database were retrospectively reviewed. Inclusion criteria were age > 18 years, minimum 1-year follow-up, and one of the following characteristics: pelvic tilt (PT) > 25 , pelvic incidence minus lumbar lordosis (PI-LL) > 10 , Cobb angle > 20 , or sagittal vertical axis (SVA) > 5 cm. Patients were categorized as undergoing cMIS (percutaneous screws with minimally invasive anterior interbody fusion) or open correction (traditional open deformity correction). Propensity matching was used to create two equal groups and to control for age, BMI, preoperative PI-LL, pelvic incidence (PI), T1 pelvic angle (T1PA), SVA, PT, and number of posterior levels fused.

RESULTS A total of 154 patients (77 underwent open procedures and 77 underwent cMIS) were included after matching for age, BMI, PI-LL (mean 15  vs 17 , respectively), PI (54  vs 54 ), T1PA (21  vs 22 ), and mean number of levels fused (6.3 vs 6). Patients who underwent three-column osteotomy were excluded. Follow-up was 1 year for all patients. Postoperative Oswestry Disability Index (ODI) (p = 0.50), Scoliosis Research Society–total (p = 0.45), and EQ-5D (p = 0.33) scores were not different between cMIS and open patients. Maximum Cobb angles were similar for open and cMIS basepatients at baseline (25.9  vs 26.3 , p = 0.85) and at 1 year postoperation (15.0  vs 17.5 , p = 0.17). In total, 58.3% of open patients and 64.4% of cMIS patients (p = 0.31) reached the minimal clinically important difference (MCID) in ODI at 1 year. At 1 year, no differences were observed in terms of PI-LL (p = 0.71), SVA (p = 0.46), PT (p = 0.9), or Cobb angle (p = 0.20). Open patients had greater estimated blood loss compared with cMIS patients (1.36 L vs 0.524 L, p < 0.05) and fewer levels of interbody fusion (1.87 vs 3.46, p < 0.05), but shorter operative times (356 minutes vs 452 minutes, p = 0.003). Revision surgery rates between the two cohorts were similar (p = 0.97).

CONCLUSIONS When cMIS was compared with open adult scoliosis correction with propensity matching, HRQOL improvement, spinopelvic parameters, revision surgery rates, and proportions of patients who reached MCID were similar between cohorts. However, well-selected cMIS patients had less blood loss, comparable results, and longer operative times in comparison with open patients.



Oblique lumbar interbody fusion at L5S1(OLIF51)

Acta Neurochirurgica (2019) 161:1079–1083

OLIF51 retains the advantages of traditional ALIF procedure with good fusion rates and improvement in radiographic parameters and reduces its drawbacks. It has the added advantage of being a minimal access technique.

Methods Preoperative analysis of the vascular anatomy using CT angiography is mandatory. OLIF51 is done in right lateral position using specialized retractor blades and Thompson retractor system. The procedure is similar to OLIF at other levels except for the differences described here. The instruments are specialized for OLIF at L5S1.

Conclusion OLIF51 provides an excellent alternative to traditional ALIF

Robot-assisted multi-level anterior lumbar interbody fusion: an anatomical study

Acta Neurochirurgica (2018) 160:1891–189

Minimally invasive surgical approaches still provide limited exposure. Access to the L2–L5 intervertebral discs during a single procedure is challenging and often requires repositioning of the patient and adopting an alternative approach.

Objectives Investigate the windows to the L2–L5 intervertebral discs to assess the dimensions of the interbody implants suitable for the procedure and evaluate the feasibility of multi-level lumbar intervertebral disc surgery in robot-assisted surgery (RAS)

Methods Sixteen fresh-frozen cadaveric specimens underwent a retroperitoneal approach to access the L2–L5 intervertebral discs. The L2–L3 to L4–L5 windows were defined as the distance between the left lateral border of the aorta (or nearest common iliac vessel) and the medial border of the psoas, measured in a static state and after gentle medial retraction of the vascular structures. Two living porcine specimens and one cadaveric specimen underwent da Vinci robot-assisted transperitoneal approach to expose the L2–L3 to L4–L5 intervertebral discs and perform multi-level discectomy and interbody implant placement.

Results The L2–L3 to L4–L5 intervertebral disc windows significantly increased from a static to a retracted state (p < 0.05). The mean L2–L3, L3–L4, and L4–L5 windows measured respectively 20.1, 21.6, and 19.6 mm in the static state, and 27.2, 30.9, and 30.3 mm after gentle vascular retraction. The intervertebral windows from L2–L3 to L4–L5 were successfully exposed through an anterior transperitoneal approach with the da Vinci robot on the cadaveric and living porcine specimens, and interbody implants were inserted.

Conclusion RAS appears to be feasible for a mini-invasive multi-level lumbar intervertebral disc surgery. The RAS procedure, longer and more expensive than conventional MIS approaches, should be reserved for elective patients.


Minimally Invasive Transforaminal Lumbar Interbody Fusion Using Banana-Shaped and Straight Cages: Radiological and Clinical Results from a Prospective Randomized Clinical Trial

Neurosurgery 82:289–298, 2018

In minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF), cage type and position play important roles in fusion achievement and sagittal alignment correction. However, no prospective randomized comparison of the results using different types of cage has been reported to date.

OBJECTIVE: To compare the radiological and clinical outcomes of unilateral MIS-TLIF using 2 types of cage.

METHODS: All candidates for single-level MIS-TLIF were randomized into banana-shaped cage and straight-cage groups. Plain radiographs and computed tomography scans were used for assessment of cage positions, fusion status, disc height, segmental lordotic angle, cage subsidence, and pelvic parameters. Clinical outcome was assessed using visual analog scale and Oswestry Disability Index scores.

RESULTS: Forty-four and 40 consecutive patients were operated on using banana-shaped and straight cages, respectively. Cage position was more anterior and lateral in the straightcage group and more medial and posterior in the banana-shaped cage group. Solid fusion was achieved in 95.2% and 96.6% of the 2 groups, respectively, at 12 mo. The change in disc height and segmental lordotic angle postoperatively was significantly greater in the banana-shaped cage group. The incidence of subsidence during follow-up was significantly higher in the banana-shaped cage group (P<.04). Clinically, the visual analog scale and Oswestry Disability Index scores decreased significantly after surgery in both groups, with no significant difference between the groups.

CONCLUSION: Our preliminary outcomes suggest that the subsidence rate may be higher using banana-shaped cages in MIS-TLIF, possibly due to their more medial final position.


Denervation and atrophy of paraspinal muscles after open lumbar interbody fusion is associated with clinical outcome

Denervation and atrophy of paraspinal muscles after open

Acta Neurochir (2014) 156:235–244

Different studies have shown that atrophy of paraspinal muscles arises after open dorsal lumbar fusion, and the reasons for this atrophy are still not yet fully clarified. This prospective study investigates the extent of atrophy of the lumbar paraspinal muscles after open lumbar interbody fu- sion, its possible causes, and their association with clinical outcome measures.

Methods Thirty consecutive patients were prospectively in- cluded (13 male, 17 female, median age 60.5 years, range 33– 80 years). Mono or bisegmental, posterior lumbar interbody fusion and instrumentation was performed applying a conven- tional, open lumbar midline approach. Clinical outcome was assessed by the Short Form (36) Health Survey (SF-36) ques- tionnaire and visual analogue scale. Needle electromyography of paraspinal muscles was performed preoperatively, at 6 and 12 months. Serum values of creatine kinase, lactate dehydro- genase and myoglobin were determined preoperatively, at day 2 after surgery and at discharge. Paraspinal muscle volume was determined by volumetric analysis of thin-slice computed tomography scans preoperatively and 1 year after surgery. Results There was a significant increase of electromyographic denervation activity (p =0.024) and reduced recruitment of motor units (p=0.001) after 1 year. Laboratory studies showed a sig- nificant increase of CK (p<0.001) and myoglobin (p < 0.001) serum levels at day 2 after surgery. The paraspinal muscle volume decreased from 67.8 to 60.4 % (p < 0.001) after 1 year. Correlation analyses revealed a significant negative correlation between denervation and muscle volume (K= -0.219, p= 0.002). Paraspinal muscle volume is significantly correlated with physical outcome (K= 0.169, p= 0.020),mental outcome (K= 0.214, p = 0.003), and pain (K = 0.382, p < 0.001) after 1 year.

Conclusions Atrophy of paraspinal muscles after open, posterior lumbar interbody fusion seems to be associated with denervation, as well as direct muscle trauma during surgery. While muscle atrophy is also correlated with a worse clinical outcome, it seems to be a determining factor for successful lumbar spine surgery.