Neurological complications using a novel retractor system for direct lateral minimally invasive lumbar interbody fusion

Female Sex and Supine Proximal Lumbar Lordosis Are Associated With the Size of the LLIF "Safe Zone" at L4-L5

STUDY DESIGN

Retrospective chart review.

OBJECTIVE

Identify demographic and sagittal alignment parameters that are independently associated with femoral nerve position at the L4-L5 disk space.

SUMMARY OF BACKGROUND DATA

Iatrogenic femoral nerve or lumbar plexus injury during lateral lumbar interbody fusion (LLIF) can result in neurological complications. The LLIF "safe zone" is the anterior half to two third of the disk space. However, femoral nerve position varies and is inconsistently identifiable on magnetic resonance imaging. The safe zone is also narrowest at L4-L5.

METHODS

An analysis of patients with symptomatic lumbar spine pathology and magnetic resonance imaging with a visibly identifiable femoral nerve evaluated at a single large academic spine center from January 1, 2017, to January 8, 2020, was performed. Exclusion criteria were transitional anatomy, severe hip osteoarthritis, coronal deformity with cobb >10 degrees, > grade 1 spondylolisthesis at L4-L5 and anterior migration of the psoas.Standing and supine lumbar lordosis (LL) and its proximal (L1-L4) and distal (L4-S1) components were measured. Femoral nerve position on sagittal imaging was then measured as a percentage of the L4 inferior endplate. A stepwise multivariate linear regression of sagittal alignment and LL parameters was then performed. Data are written as estimate, 95% CI.

RESULTS

Mean patient age was 58.2±14.7 years, 25 (34.2%) were female and 26 (35.6%) had a grade 1 spondylolisthesis. Mean femoral nerve position was 26.6±10.3% from the posterior border of L4. Female sex (-6.6, -11.1 to -2.1) and supine proximal lumbar lordosis (0.4, 0.1-0.7) were independently associated with femoral nerve position.

CONCLUSIONS

Patient sex and proximal LL can serve as early indicators of the size of the femoral nerve safe zone during a transpsoas LLIF approach at L4-L5.

Lateral and Oblique Lumbar Interbody Fusion-Current Concepts and a Review of Recent Literature

PURPOSE

To review the relevant recent literature regarding minimally invasive, lateral, and oblique approaches to the anterior lumbar spine, with a particular focus on the operative and postoperative complications.

METHODS

A literature search was performed on Pubmed and Web of Science using combinations of the following keywords and their acronyms: lateral lumbar interbody fusion (LLIF), oblique lateral interbody fusion (OLIF), anterior-to-psoas approach (ATP), direct lateral interbody fusion (DLIF), extreme lateral interbody fusion (XLIF), and minimally invasive surgery (MIS). All results from January 2016 through January 2019 were evaluated and all studies evaluating complications and/or outcomes were included in the review.

RECENT FINDINGS

Transient neurological deficit, particularly sensorimotor symptoms of the ipsilateral thigh, remains the most common complication seen in LLIF. Best available current literature demonstrates that approximately 30-40% of patients have postoperative deficits, primarily of the proximal leg. Permanent symptoms are less common, affecting 4-5% of cases. Newer techniques to reduce this rate include different retractors, direct visualization of the nerves, and intraoperative neuromonitoring. OLIF may have lower deficit rates, but the available literature is limited. Subsidence rates in both LLIF and OLIF are comparable to ALIF (anterior lumbar interbody fusion), but further study is required. Supplemental posterior fixation is an active area of investigation that shows favorable biomechanical results, but additional clinical studies are needed. Minimally invasive lumbar interbody fusion techniques continue to advance rapidly. As these techniques continue to mature, evidence-based risk-stratification systems are required to better guide both the patient and clinician in the joint decision-making process for the optimal surgical approach.

Patient Care During Minimally Invasive Lateral Spine Surgery: 1.7 www.aornjournal.org/content/cme

Perioperative nurses care for patients undergoing a wide range of surgical procedures. One fast-growing surgical specialty is spine surgery performed using minimally invasive techniques. Patients may be candidates for minimally invasive spine surgery based on their presenting signs and symptoms and medical imaging test results. Open anterior and posterior surgical approaches to spine surgery are how surgeons traditionally have performed these procedures. However, new technology has enabled a minimally invasive lateral approach to the spine. This approach minimizes many of the risks and challenges associated with both the anterior and posterior approaches. Minimally invasive lateral interbody fusion requires the perioperative nurse to have a thorough understanding of the necessary patient positioning, spinal anatomy, and OR suite setup to ensure a safe and successful surgical experience for the patient.

Patients with High Pelvic Tilt Achieve the Same Clinical Success as Those with Low Pelvic Tilt After Minimally Invasive Adult Deformity Surgery

BACKGROUND

Pelvic tilt (PT) is a compensatory mechanism for adult spinal deformity patients to mitigate sagittal imbalance. The association between preop PT and postop clinical and radiographic outcomes has not been well studied in patients undergoing minimally invasive adult deformity surgery.

OBJECTIVE

To evaluate clinical and radiographic outcomes in adult spinal deformity patients with high and low preoperative PT treated surgically using less invasive techniques.

METHODS

Retrospective case-control, institutional review board-approved study. A multicenter, minimally invasive surgery spinal deformity patient database was queried for 2-yr follow-up with complete radiographic and health-related quality of life (HRQOL) data. Hybrid surgery patients were excluded. Inclusion criteria were as follows: age > 18 and either coronal Cobb angle > 20, sagittal vertical axis > 5 cm, pelvic incidence-lumbar lordosis (PI-LL) > 10 or PT > 20. Patients were stratified by preop PT as per Schwab classification: low (PT< 20), mid (PT 20-30), or high (>30). Postoperative radiographic alignment parameters (PT, PI, LL, Cobb angle, sagittal vertical axis) and HRQOL data (Visual Analog Scale Back/Leg, Oswestry Disability Index) were evaluated and analyzed.

RESULTS

One hundred sixty-five patients had complete 2-yr outcomes data, and 64 patients met inclusion criteria (25 low, 21 mid, 18 high PT). High PT group had higher preop PI-LL mismatch (32.1 vs 4.7; P < .001). At last follow-up, 76.5% of patients in the high PT group had continued PI-LL mismatch compared to 34.8% in the low PT group (P < .006). There was a difference between groups in terms of postop changes of PT (-3.9 vs 1.9), LL (8.7 vs 0.5), and PI-LL (-9.5 vs 0.1). Postoperatively, HRQOL data (Oswestry Disability Index and Visual Analog Scale) were significantly improved in both groups (P < .001).

CONCLUSION

Adult deformity patients with high preoperative PT treated with minimally invasive surgical techniques had less radiographic success but equivalent clinical outcomes as patients with low PT.