Use of motor evoked potentials during lateral lumbar interbody fusion reduces postoperative deficits

Background Context

Intraoperative neurophysiological monitoring (IONM) has gained rather widespread acceptance as a method to mitigate risk to the lumbar plexus during lateral lumbar interbody fusion (LLIF) surgery. The most common approach to IONM involves using only electromyography (EMG) monitoring, and the rate of postoperative deficit remains unacceptably high. Other test modalities, such as transcranial electric motor-evoked potentials (tcMEPs) and somatosensory-evoked potentials, may be more suitable for monitoring neural integrity, but they have not been widely adopted during LLIF. Recent studies have begun to examine their utility in monitoring LLIF surgery with favorable results.

Mini-open lateral retroperitoneal lumbar spine approach using psoas muscle retraction technique. Technical report and initial results on six patients

Purpose

The main aim of this paper was to report reproducible method of lumbar spine access via a lateral retroperitoneal route.

Methods

The authors conducted a retrospective analysis of the technical aspects and clinical outcomes of six patients who underwent lateral multilevel retroperitoneal interbody fusion with psoas muscle retraction technique. The main goal was to develop a simple and reproducible technique to avoid injury to the lumbar plexus.

Results

Six patients were operated at 15 levels using psoas muscle retraction technique. All patients reported improvement in back pain and radiculopathy after the surgery. The only procedure-related transient complication was weakness and pain on hip flexion that resolved by the first follow-up visit.

Conclusions

Psoas retraction technique is a reliable technique for lateral access to the lumbar spine and may avoid some of the complications related to traditional minimally invasive transpsoas approach.     

Technical description of oblique lateral interbody fusion at L1–L5 (OLIF25) and at L5–S1 (OLIF51) and evaluation of complication and fusion rates

Background Context

The oblique lateral interbody fusion (OLIF) procedure is aimed at mitigating some of the challenges seen with traditional anterior lumbar interbody fusion (ALIF) and transpsoas lateral lumbar interbody fusion (LLIF), and allows for interbody fusion at L1–S1.

Lumbar plexopathy following instrumented posterior lumbar interbody fusion: a complication with use of Hohmann’s retractor

Introduction

A series of 12 patients in our centre following single level instrumented posterior lumbar interbody fusion at L4–L5 developed unexplainable motor weakness in the proximal lumbar nerve roots (L2, L3) and numbness of the whole limb, a clinical picture resembling lumbar plexopathy. Even though lumbar plexopathy has been reported following gynaecological procedures and in transpsoas interbody fusion surgeries, there is no literature reporting this complication following conventional instrumented posterior lumbar interbody fusions.

Study design

Retrospective observational study.

Objective

To find the possible mechanism of development of lumbar plexopathy in patients who underwent posterior lumbar interbody fusion surgeries in our centre.

Material and methods

We analyzed retrospectively the medical records, electrophysiological reports of the patients, literatures on the anatomy of lumbar plexus and other literature reporting similar complications. We also dissected lumbar plexus of three cadavers and simulated surgical technique on them to find the mechanism of development of this unusual complication.

Results

We found injury to lumbar plexus that probably occurred intraoperatively with Hohmann’s retractor that was used for retraction of the paraspinal muscles. This theory was favoured by many clinical factors and further confirmed by cadaveric dissections.

Conclusion

We conclude that surgical technique with improper use of Hohmann’s retractor causes traction and compression injury to the lumbar plexus resulting in this complication. We propose proper technique of insertion of Hohmann’s retractor and also recommend use of modified Hohmann’s retractor with shorter tips for spinal procedures to prevent such complication.     

Transient neurological deficit following midthoracic decompression for severe stenosis: a series of three cases

Purpose

To report three cases of transient perioperative neurological deficit in the absence of direct cord insult following decompression of the severely stenotic thoracic spine.

Methods

The clinical and radiographic electronic medical records of three patients who underwent decompression for severe midthoracic stenosis with transient neurological deficits perioperatively were reviewed. The cases are presented with consideration of possible underlying mechanisms and multimodality intraoperative monitoring (IOM) findings.

Results

Two patients had neurologic changes on IOM and Stagnara wake-up test, the remaining patient had absent motor and sensory potentials at baseline and throughout the case. IOM changes were observed immediately following decompression in the absence of direct cord insult or displacement. Postoperatively all patients experienced neurological motor deficits which presented as complete paralysis of the right lower extremity in two of the patients and the left lower extremity in one patient. The deficit was transient—improvement of motor strength occurred between 1 and 13 months of follow-up in all patients.

Conclusion

Decompression of a severely stenotic region of the thoracic spinal cord may lead to a complete yet transient motor deficit in the perioperative period in the absence of direct mechanical cord insult. Potential etiologies include ischemia-reperfusion injury, microthrombi, and altered perfusion due to internal recoil of spinal cord architecture following decompression. IOM may show conspicuous findings in such events, however, may not be relied upon when baseline potentials are sub-optimal. Recognition of this short-lived neurological deficit following decompression of the severely stenotic thoracic spine will improve preoperative patient counseling and merits further study for determination of the precise pathophysiology.     

Minimally invasive transforaminal lumber interbody fusion and degenerative lumbar spine disease

Objective

The purpose of this study was to assess the clinical and radiological outcomes of minimally invasive transforaminal lumbar interbody fusion (MI-TLIF) surgery for degenerative lumbar spine disease.

Methods

A prospective analysis of 34 consecutive patients who underwent a MI-TLIF using image guidance between July 2008 and November 2010. The patient group comprised 19 males and 15 females (mean age 56), 23 of whom had undergone additional reduction of spondylolisthesis. All patients underwent post-operative CT imaging to assess pedicle screw, cage placement and fusion at 6 months. Oswestry Disability Index (ODI) scores were recorded pre-operatively and at 6-month follow up.

Results

33/34 (97.1 %) patients showed evidence of fusion at 6 months with a mean improvement of 27 on ODI scores. The mean length of hospital stay was 4 days. The mean operative time was 173 min.

Complications observed

1/34 (2.9 %) suffered a pulmonary embolism and 1/34 (2.9 %) patients developed transient nerve root pain post-operatively. There were no occurrences of infection and no post-operative CSF leaks.

Conclusion

MI-TLIF offers patients a safe and effective surgical treatment option to treat degenerative lumbar spine disease.     

Minimally invasive versus open transforaminal lumbar interbody fusion: a meta-analysis based on the current evidence

Purpose

This is a meta-analysis of randomized and non-randomized studies comparing the clinical and radiological efficacy of minimally invasive (MI) and conventional open transforaminal lumbar interbody fusion (open-TLIF) for degenerative lumbar diseases.

Methods

A literature search of the MEDLINE database identified 11 studies that met our inclusion criteria. A total of 785 patients were examined. Pooled estimates of clinical and radiological outcomes, and corresponding 95 % confidence intervals were calculated.

Results

The pooled data revealed that MI-TLIF was associated with less blood loss, shorter hospital stay, and a trend of better functional outcomes when compared with open-TLIF. However, MI-TLIF significantly increased the intraoperative X-ray exposure. Both techniques had similar operative time, complication rate, and re-operation rate.

Conclusions

Based on the available evidence, MI-TLIF for degenerative lumbar diseases might lead to better patient-based outcomes. MI-TLIF would be a promising procedure, but extra efforts are needed to reduce its intraoperative radiation exposure. More randomized controlled trials are needed to compare these two surgical options.     

Evaluation of hip flexion strength following lateral lumbar interbody fusion

Background context

Lateral interbody fusion (LIF) is a minimally invasive procedure that is designed to achieve a solid interbody fusion while minimizing the damage to the surrounding soft tissue. Although short-term results have been promising, few data have been published to date regarding its risks and complication rate.

Purpose

The aim was to evaluate the extent of injury to the psoas muscle after the LIF procedure by measuring hip flexion strength.

Study design

A prospective case series was used in the study.

Method

Hip flexion strength was measured using a handheld digital dynamometer while the patient was seated on a chair; the examiner held the device against the patient’s attempt to flex the hip. Both sides were measured to compare the operated and nonoperated psoas muscles. Each side was measured three times and the average amount (in pounds) was recorded. Measurements were done before and after surgery on Day 2-3, at 2 weeks, 6 weeks, and at 3 and 6 months.

Results

Thirty-three patients were recruited for this study. Mean preoperative hip flexion strength values were 20.7±3.47 lb and 21.3±4.31 lb for operated and nonoperated legs, respectively, with no significant difference (p=.85). With a mean of 11.2±2.24 lb postoperative measurements on Day 2, the operated side showed statistically significant reduction of strength (p=.0001). The nonoperated side was also weaker postoperatively, but not significantly (mean=19.12±1.74 lb; p=.097). From the first follow-up visit at 2 weeks, the values on the operated leg had returned to baseline values (20.6, p=.97) and were not significantly different from preoperative values on either side.

Discussion

Hip flexion was weakened immediately after the LIF procedure, which may be attributed to psoas muscle injury during the procedure. However, this damage was temporary, with almost complete return to baseline values by 2 weeks.     

Lateral lumbar interbody fusion: a systematic review of complication rates

Background Context

Lateral lumbar interbody fusion (LLIF) is a frequently used technique for the treatment of lumbar pathology. Despite its overall success, LLIF has been associated with a unique set of complications. However, there has been inconsistent evidence regarding the complication rate of this approach.

Comparison of pure lateral and oblique lateral inter-body fusion for treatment of lumbar degenerative disk disease: a multicentric cohort study

Purpose

The most effective interbody fusion technique for degenerative disk disease (DDD) is still controversial. The purpose of our study is to compare pure lateral (LLIF) and oblique lateral (OLIF) approaches for the treatment of lumbar DDD from L1–L2 to L4–L5, in terms of clinical and radiological outcomes.

Materials and methods

45 patients underwent lumbar interbody fusion for pure lumbar DDD from  L1–L2 to L4–L5 through LLIF (n?=?31, mean age 62.1 years, range 45–78 years) or OLIF (n?=?14, mean age 57.4 years, range 47–77 years). Clinical evaluations were performed with ODI and SF-36 tests. Radiological assessment was based on the modification of coronal segmental Cobb angles and segmental lumbar lordosis (L1–S1).

Results

On ODI and SF-36, all patients presented good results at follow-up, with 26% the difference between the LIF and OLIF groups on ODI scale in the post-operative period, and 3.9 and 8.8 points difference on physical and mental SF-36 in favor of OLIF. Radiological parameters improved significantly in both groups. The mean correction was 6.25° for cCobb (11.3° in LIF and 1.9° in OLIF), 2.5° for sLL (2° in LLIF and 4° in OLIF).

Conclusions

LLIF and OLIF represent safe and effective MIS procedures for the treatment of lumbar DDD. LLIF had some risks of motor deficit and monitoring is mandatory, though it addressed more the coronal deformities. OLIF did not imply risks for motor deficits, but attention should be paid to vascular anatomy. It was more effective in kyphotic segmental deformities.

Graphical abstract

These slides can be retrieved under Electronic Supplementary material.

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The surgical vascular anatomy of the minimally invasive lateral lumbar interbody approach: a cadaveric and radiographic analysis

Purpose

The minimally invasive (MI) lateral lumbar interbody fusion (LLIF) approach has become increasingly popular for the treatment of degenerative lumbar spine disease. The neural anatomy of the lumbar plexus has been studied; however, the pertinent surgical vascular anatomy has not been examined in detail. The goal of this study is to examine the vascular structures that are relevant in relation to the MI-LLIF approach.

Methods

Anatomic dissection of the lumbar spines and associated vasculature was performed in three embalmed, adult cadavers. Right and left surgeon perspective views during LLIF were for a total of six approaches. During the dissection, all vascular elements were noted and photographed, and anatomical relationships to the vertebral bodies and disc spaces were analyzed. In addition, several axial and sagittal MRI images of the lumbar spine were analyzed to complement the cadaveric analysis.

Results

The aorta descends along the left anterior aspect of lumbar vertebra with an average distance of 2.1 cm (range 1.9–2.3 cm) to the center of each intervertebral disc. The vena cava descends along the right anterior aspect of lumbar vertebrates with average distance of 1.4 cm (range 1.3–1.6 cm) to the center of the intervertebral disc. Each vertebral body has two lumbar arteries (direct branches from the aorta); one exits to the left and one to the right side of the vertebral body. The lumbar arteries pass underneath the sympathetic trunk, run in the superior margin of the vertebral body and extend all the way across it, with average length of 3.8 cm (range 2.5–5 cm). The mean distance between the arteries and the inferior plate of the superior disc space is 4.2 mm (range 2–5 mm) and mean distance of 3.1 cm (range 2.8–3.8 cm) between two arteries in adjacent vertebrae. One of the cadavers had an expected normal anatomical variation where the left arteries at L3–L4 anastomosed dorsally of the vertebral bodies at the middle of the intervertebral disc.

Conclusions

Understanding the vascular anatomy of the lateral and anterior lumbar spine is paramount for successfully and safely executing the LLIF procedure. It is imperative to identify anatomical variations in lumbar arteries and veins with careful assessment of the preoperative imaging.

     

Biomechanics of lateral plate and pedicle screw constructs in lumbar spines instrumented at two levels with laterally placed interbody cages

Background context

The lateral transpsoas approach to interbody fusion is gaining popularity because of its minimally invasive nature and resultant indirect neurologic decompression. The acute biomechanical stability of the lateral approach to interbody fusion is dependent on the type of supplemental internal fixation used. The two-hole lateral plate (LP) has been approved for clinical use for added stabilization after cage instrumentation. However, little biomechanical data exist comparing LP fixation with bilateral pedicle screw and rod (PSR) fixation.

Purpose

To biomechanically compare the acute stabilizing effects of the two-hole LP and bilateral PSR fusion constructs in lumbar spines instrumented with a lateral cage at two contiguous levels.

Study design

Biomechanical laboratory study of human cadaveric lumbar spines.

Methods

Eighteen L1–S1 cadaveric lumbar spines were instrumented with lateral cages at L3–L4 and L4–L5 after intact kinematic analysis. Specimens (n=9 each) were allocated for supplemental instrumentation with either LP or PSR. Intact versus instrumented range of motion was evaluated for all specimens by applying pure moments (±7.5 Nm) in flexion/extension, lateral bending (LB) (left+right), and axial rotation (AR) (left+right). Instrumented spines were later subjected to 500 cycles of loading in all three planes, and interbody cage translations were quantified using a nonradiographic technique.

Results

Lateral plate fixation significantly reduced ROM (p<.05) at both lumbar levels (flexion/extension: 49.5%; LB: 67.3%; AR: 48.2%) relative to the intact condition. Pedicle screw and rod fixation afforded the greatest ROM reductions (p<.05) relative to the intact condition (flexion/extension: 85.6%; LB: 91.4%; AR: 61.1%). On average, the largest interbody cage translations were measured in both fixation groups in the anterior-posterior direction during cyclic AR.

Conclusions

Based on these biomechanical findings, PSR fixation maximizes stability after lateral interbody cage placement. The nonradiographic technique served to quantify migration of implanted hardware and may be implemented as an effective laboratory tool for surgeons and engineers to better understand mechanical behavior of spinal implants.     

The learning curve of lateral access lumbar interbody fusion in an Asian population: a prospective study

Purpose

Lateral access lumbar interbody fusion (LLIF) is a minimally invasive technique that has an increasing popularity. It offers unique advantages and circumvents risk of certain serious complications encountered in other conventional spinal approaches. This study provides a statistical analysis defining the lateral access learning curve in the Asian population.

Methods

This prospective study included 32 consecutive patients who underwent LLIF from April 2012 to August 2014. The surgeries were performed by two senior spine surgeons and follow-up was conducted at 6 weeks, 3, 6, 9 months and 1 year post-operation.

Results

The breakpoint in operating time occurred at the 22nd level operated, from a mean of 71 min in the early phase group to a mean of 42 min in the steady state group. LLIF at L4/5 level is technically more demanding but technically feasible as competency is achieved.

Conclusions

During the learning process, there was no compromise of perioperative or clinical outcomes. It should be feasibly incorporated into a spine surgeon’s repertoire of procedures for the lumbar spine.

     

Use of the LION procedure on the sensitive branches of the lumbar plexus for the treatment of intractable postherniorrhaphy neuropathic inguinodynia

Purpose

To report on the use of the laparoscopic implantation of neuroprosthesis (LION) procedure on the sensitive branches of the lumbar plexus for the treatment of refractory postherniorrhaphy neuropathic inguinodynia.

Methods

Laparoscopic exposure and implantation of an electrode to the different nerves is undertaken by the transumbilical transperitoneal approach. The genitofemoral nerve is identified on the anterior surface of the psoas major muscle, the ilioinguinal, iliohypogastric, and of the lateral femoral cutaneous nerves on the anterior surface of the quadratus lumborum muscle behind the kidney and colon. A quadripolar electrode is placed laparoscopically in direct contact with the injured nerve(s).

Results

All patients included in this series had reported failure of all previous treatments. Twenty-three consecutive patients were included in this series. Success, defined as visual analog scale (VAS) reduction >50%, was obtained in 19 patients. To date (mean follow-up 28.61 months [±16.2; min. 6 months to max. 68 months]), 11 patients report a reduction of the mean VAS of more than 80% and eight report a reduction of between 50 and 80%; the mean VAS score could be reduced, so far, from 8.1 (±8.1; range 6–10) preoperatively to 3.1 (±2.8; range 0–5) postoperatively (P < 0.001).

Conclusions

The presented technique of laparoscopic implantation permits a selective implantation and neuromodulation of all sensitive branches of the lumbar plexus. These preliminary results suggest that the technique described is effective, safe, minimally invasive, and must be indicated in patients after failure of all other treatments.     

Image changes of paraspinal muscles and clinical correlations in patients with unilateral lumbar spinal stenosis

Study design

This is a retrospective study.

Purpose

To compare the morphometric parameters of the psoas major and lumbar multifidus muscles in lumbar spinal stenosis (LSS) patients exhibiting different functional performance.

Summary of background data

LSS refers to symptoms related to size reduction of the lumbar spinal canal; however, the degree of stenosis is poorly related to symptom severity and functional impairments. Morphometric changes in the paraspinal muscles have been correlated with chronic lower back pain in previous studies. However, correlations between the functional performance of LSS patients and the morphometric changes in paraspinal muscles have seldom been reported.

Methods

Sixty-six LSS patients without mechanical back pain or segmental instability were enrolled in the study. A review of their medical records and MRI images was performed. Morphometric parameters, including the fatty infiltration (FI) of the lumbar multifidus muscle as well as the relative cross-sectional area (RCSA) of the psoas major and lumbar multifidus muscles, were measured. Subjects were divided into high and low functional performance groups according to their Japanese Orthopedic Association (JOA) scores.

Results

The male LSS patients exhibited a larger psoas RCSA than the female patients, whereas the older patients exhibited a smaller psoas RCSA and higher multifidus FI than the younger patients. LSS patients in the high functional performance group exhibited a significantly larger psoas RCSA and lower multifidus FI.

Conclusion

The psoas RCSA and multifidus FI can be used as predictive factors for functional performance in LSS patients.     

Transforaminal lumbar interbody fusion (TLIF) versus posterolateral instrumented fusion (PLF) in degenerative lumbar disorders: a randomized clinical trial with 2-year follow-up

Purpose

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.     

Vertebral body fracture following stand-alone lateral lumbar interbody fusion (LLIF): report of two events out of 712 levels

Purpose

Available studies demonstrate vertebral body fractures as a relatively rare complication following lateral lumbar interbody fusion (LLIF), with most fractures reported in association with lateral plating and vertebral screws. This study reports the occurrence of two vertebral body fractures following stand-alone LLIF in 712 levels fused in 335 patients.

Methods

A retrospective review of prospectively collected data was performed on all patients who underwent minimally invasive LLIF over a seven-year period at a single institution. Patients with vertebral body fractures were recorded.

Results

Two patients (0.6 %) out of 335 total patients (712 levels) were identified with vertebral body fractures following stand-alone LLIF. Both patients presented with severe back pain and return of symptoms within 2 weeks of the index surgery. Both patients were obese, had impaired bone mineral density and were managed with open posterior segmental fixation.

Conclusions

The 0.6 % incidence of vertebral body fractures in our series of fusing 712 levels is in accordance with the incidence rates reported in the literature. Potential risk factors for vertebral body fractures at the index LLIF level included obesity, osteopenia, unrecognized intraoperative endplate breach, graft subsidence and oversized graft placement.

     

Biomechanical analysis of lateral interbody fusion strategies for adjacent segment degeneration in the lumbar spine

Background Context

Surgical treatment of symptomatic adjacent segment disease (ASD) typically involves extension of previous instrumentation to include the newly affected level(s). Disruption of the incision site can present challenges and increases the risk of complication. Lateral-based interbody fusion techniques may provide a viable surgical alternative that avoids these risks. This study is the first to analyze the biomechanical effect of adding a lateral-based construct to an existing fusion.