Quantitative Threshold of Intraoperative Radiological Parameters for Suspecting Oblique Lumbar Interbody Fusion Cage Malposition Triggering Contralateral Radiculopathy.

BACKGROUND: This study aimed to clarify the quantitative threshold of intraoperative radiological parameters for suspecting posterior malposition of the oblique lumbar interbody fusion (OLIF) cage triggering contralateral radiculopathy. METHODS: We measured the sagittal center and axial rotation angle (ARA) of the cage using postoperative computed tomography (CT) in 130 patients (215 cages) who underwent OLIF. The location of the cage tip was determined from axial magnetic resonance imaging in selected cases based on CT simulations to assess whether the cage was in contact with the contralateral exiting nerve or whether the surgical instruments could contact the nerve during intradiscal maneuvers. RESULTS: The sagittal center of the cages was on average 41.5% from the anterior edge of the endplate (shown as AC/AP value: anterior end plate edge-cage center/anterior-posterior endplate edge ×100%), and posterior cage positioning ≥50% occurred in 14% of the cages. The ARA was -2.9°, and posterior oblique rotation of the cages ≥10° (ARA ≤ -10°) was observed in 13%. CT simulation showed that the cage tip could directly contact the contralateral nerve when the cage was placed deep in the posterior portion ≥50% of the AC/AP values with concomitant posterior axial rotation ≥10° (ARA ≤ -10°), or deep in an extremely rare portion ≥60% of the AC/AP values with posterior axial rotation ≥0° (ARA ≤ 0°). Six percent of the cages (13/215) were placed in these posterior oblique areas (potential contact area: PCA). Three cages in the PCA were in direct contact with the contralateral nerves, and 9 were placed deep just anterior to the nerves. Symptomatic contralateral radiculopathy occurred in 2 cages (2/13/215, 15.3%/0.9%). CONCLUSIONS: Two intraoperative radiological parameters (AC/AP and ARA) measurable during OLIF procedures may become practical indicators for suspecting cage malposition in PCA and may be available when determining whether to consider cage revision intraoperatively to a more ventral disc space or anteriorly from the opposite endplate edge.

Contralateral lower limb radiculopathy by extraforaminal disc herniation following oblique lumbar interbody fusion in degenerative lumbar disorder: illustrative cases.

BACKGROUND: Contralateral lower limb radiculopathy is a potential early complication of oblique lumbar interbody fusion (OLIF) in degenerative lumbar disorders. Among several pathologies related to contralateral radiculopathy following OLIF, extraforaminal disc herniation during the OLIF procedure is very rare. OBSERVATIONS: Case 1 is a 68-year-old male underwent L4-5 and L5-6 OLIF for recurrent lumbar canal stenosis-expressed right leg pain and muscle weakness after surgery. Case 2 is a 76-year-old female on whom L4-5 OLIF was performed for L4 degenerative spondylolisthesis and who presented right leg pain and numbness postoperatively. In both patients, OLIF cages were inserted into the posterior part of the disc space or obliquely and the extraforaminal extruded disc compressed opposite exiting nerve roots (L5 root in case 1 and L4 root in case 2) as shown on magnetic resonance imaging (MRI). Surgical decompression with discectomy was required for pain relief and neurological improvement in both cases. LESSONS: When emerging from new-onset opposite limb radiculopathy attributed to the OLIF procedure, extraforaminal disc herniation should be considered a potential pathology and MRI is useful for early diagnosis and selecting a subsequent management, including surgery.

[Causes of asymptomatic side limb pain after minimally invasive transforaminal lumbar interbody fusion].

OBJECTIVE: To investigate possible causes and preventive measures for asymptomatic pain in the limbs after minimally invasive transforaminal lumbar interbody fusion(MIS-TLIF). METHODS: Clinical data from 50 patients with lumbar degenerative disease who underwent MIS-TLIF between January 2019 and September 2020 were retrospectively analyzed. The group included 29 males and 21 females aged from 33 to 72 years old, with an average age of (65.3±7.13) years. Twenty-two patients underwent unilateral decompression, and 28 underwent bilateral decompression. The side(ipsilateral or contralateral) and site(low back, hip, or leg) of the pain were recorded before surgery, 3 days after surgery, and 3 months after surgery. The pain degree was evaluated using the visual analogue scale(VAS) at each time point. The patients were further grouped based on whether contralateral pain occurred postoperatively (8 cases in the contralateral pain group and 42 in the no contralateral pain group), and the causes and preventive measures of pain were analyzed. RESULTS: All surgeries were successful, and the patients were followed up for at least 3 months. Preoperative pain on the symptomatic side improved significantly, with the VAS score decreasing from (7.00±1.79) points preoperatively to (3.38±1.32) points at 3 days postoperatively and (3.98±1.17) points at 3 months postoperatively. Postoperative asymptomatic side pain (contralateral pain) occurred in 8 patients within 3 days after surgery, accounting for 16% (8/50) of the group. The sites of contralateral pain included the lumbar area (1 case), hip(6 cases), and leg (1 case). The contralateral pain was significantly relieved 3 months after surgery. CONCLUSION: More cases of contralateral limb pain occur after unilateral decompression MIS-TLIF, and the reason may include contralateral foramen stenosis, compression of medial branches, and other factors. To reduce this complication, the following procedures are recommended: restoring intervertebral height, inserting a transverse cage, and withdrawing screws minimally.

Contralateral radiculopathy after unilateral transforaminal lumbar interbody fusion: causes and prevention.

BACKGROUND: Unilateral transforminal lumbar interbody fusion (TLIF) with a single cage can provide circumferential fusion and biomechanical stability. However, the causes and prevention of contralateral radiculopathy following unilateral TLIF remain unclear. METHODS: In total, 190 patients who underwent unilateral TLIF from January 2017 to January 2019 were retrospectively reviewed. Radiological parameters including lumbar lordosis, segmental angle, anterior disc height, posterior disc height (PDH), foraminal height (FH), foraminal width, and foraminal area (FA) were measured preoperatively and postoperatively. Preoperative and postoperative visual analog scale scores were also recorded. RESULTS: The incidence of contralateral radiculopathy after unilateral TLIF was 5.3% (10/190). The most common cause was contralateral foraminal stenosis. Unilateral TLIF could increase the lumbar lordosis, segmental angle, and anterior disc height but decrease the PDH, FA, and FH in patients with symptomatic contralateral radiculopathy. The intervertebral cage should be placed to cover the epiphyseal ring and cortical compact bone of the midline, and the disc height can be increased to enlarge the contralateral foramen. CONCLUSION: The most common cause of contralateral radiculopathy is contralateral foraminal stenosis. Careful preoperative planning is necessary to achieve satisfactory outcomes. Improper unilateral TLIF will decrease the PDH, FA, and FH, resulting in contralateral radiculopathy.

Lumbar Disc Herniations Causing Contralateral Radicular Symptoms: Can They Be Explained by Hypotenusal Theory?

OBJECTIVE: Cases presenting contralateral radicular symptoms are rarely encountered. It is difficult to decide on the correct side in cases where surgical intervention will be performed. The aim of the study is to explain the symptomatology in cases of lumbar disc herniations causing contralateral radicular symptoms by a hypotenusal effect. MATERIALS AND METHODS: In total, 27 cases were included in the study. Eight cases underwent surgical interventions performed on the side where disc herniation was radiologically detected. Nineteen cases were treated conservatively. Disc herniations were radiologically evaluated in 3 different groups, and the effect on the root on the symptomatic side was explained by a hypotenusal theory. Correlations among symptomatology, clinical findings, magnetic resonance imaging, and electromyography were discussed. RESULTS: Clinical improvement was observed in all cases that were operated on the side where disc herniation was detected radiologically. Neurologic examination findings in the postoperative period also revealed the correctness of the selected surgical approach. Electromyography is insufficient to explain clinical findings and to decide on the surgical side. CONCLUSION: Lumbar disc herniations, which lead to contralateral radicular symptoms, should be operated from the side where the disc is radiologically detected. The top of the disc is responsible for symptomatology. Surgical excision of the top of the disc removes the contralateral root traction and root compression on the same side.