Hirohito Kanamoto

Perioperative Complications in 155 Patients Who Underwent Oblique Lateral Interbody Fusion Surgery: Perspectives and Indications From a Retrospective, Multicenter Survey.

Study Design. A retrospective multicenter survey. Objective. To investigate the perioperative complications of oblique lateral interbody fusion (OLIF) surgery. Summary of Background Data. OLIF has been widely performed to achieve minimally invasive, rigid lumbar lateral interbody fusion. The associated perioperative complications are not yet well described. Methods. The participants were patients who underwent OLIF surgery under the diagnosis of degenerative lumbar diseases between April 2013 and May 2015 at 11 affiliated medical institutions. The collected data were classified into intraoperative and early-stage postoperative (⩽1 mo) complications. The intraoperative complications were then subcategorized into organ damage (neural, vertebral, vascular, and others) and other complications, mainly related to instrumental failure. The collected data were also divided and analyzed based on whether the surgeon was certified to perform the surgery and the incidence of complications in the early (April 2013–March 2014) and late stages (April 2014–May 2015) of OLIF introduction. Results. In the 155 included patients, 75 complications were reported (incidence rate, 48.3%). The most common complication was endplate fracture/subsidence (18.7%), followed by transient psoas weakness and thigh numbness (13.5%) and segmental artery injury (2.6%). Almost all these complications were transient, except for three patients who had permanent damage: one had ureteral injury and two had neurological injury. Postoperative complications included surgical site infection (1.9%) and reoperation (1.9%). Whether the primary operator was experienced did not affect the incidence of complications. Regarding the introductory stage, the incidence of complications was 50% in the early stage and 38% in the late stage. Conclusion. The overall incidence of perioperative complications of OLIF surgery reached 48.3%, of which only 1.9% resulted in permanent damage. Our analysis based on surgeon experience indicated that the OLIF procedure could be performed without increasing incidence of complications, under the guidance of experienced supervisors. Level of Evidence: 3

The diagnosis of double-crush lesion in the L5 lumbar nerve using diffusion tensor imaging

BACKGROUND CONTEXT A double-crush lesion is a condition in which the lumbar nerve is compressed both medially and laterally in the spinal canal, where diagnosis can be very difficult, and is a factor leading to poor surgical success rates. PURPOSE Diffusion tensor imaging (DTI) was used to determine DTI parameter fractional anisotropy (FA) values and apparent diffusion coefficient (ADC) in both intraspinal column lesions alone and in double-crush lesions. STUDY DESIGN This study used a prospective study. PATIENT SAMPLE Of the 56 cases (mean age: 72.2 years) that underwent laminectomy for lumbar spinal stenosis at our clinic between April 2013 to March, 2015, 10 cases with L5 radiculopathy caused by L4-L5 stenosis (Intraspinal stenosis group (Group I); mean age: 74.7 years), and 5 cases with persistent symptoms caused by L5 foraminal stenosis despite L4-L5 decompression surgery (Double-crush group (Group D); mean age: 77.6 years) were targeted. One patient in Group D was diagnosed through microendoscopic intrapedicular partial pediculotomy and the remaining four cases by nerve root infiltration. Five healthy cases (mean age: 54 years) were studied as controls. OUTCOME MEASURES Intraspinal zone (Iz), nerve root (N), and extraforaminal zone (Ez) were established as the regions of interest, and the L5 nerve FA and ADC values were determined on the affected side. METHODS Diffusion tensor imaging was performed prospectively by 1.5T magnetic resonance imaging before surgery, and DTI parameters of L5 nerve were evaluated in all patients and healthy volunteers. Student t test was used for group comparisons, and a p<.05 was considered statistically significant. RESULTS Fractional anisotropy values (Iz, N, Ez) were 0.415, 0.448, and 0.517, respectively, increasing as sites became more distal. Group I values were 0.335, 0.393, and 0.484, and Group D values were 0.296, 0.367, and 0.360. Compared with the healthy volunteers, Group D had significantly lower Iz (p<.05) and Ez (p<.001) values, while Group I had significantly lower Iz (p<.05) values. In Group D, Ez FA values were significantly lower (p<.001) than in Group I. Apparent diffusion coefficient values (Iz, N, Ez) in the healthy control group were 1.270 mm2/s, 1.151 mm2/s, and 0.937 mm2/s with values decreasing as sites grew distal. In Group I, the ADC values were 1.406 mm2/s, 1.184 mm2/s, and 1.001 mm2/s, while in Group D they were 1.551 mm2/s, 1.412 mm2/s, and 1.329 mm2/s. Compared with the healthy volunteers, Iz (p<.05) and Ez (p<.05) values were significantly higher in Group D. The N (p<.01) and Ez (p<.001) ADC values were significantly higher in Group D than in Group I. CONCLUSIONS Depending on where the nerve was compressed, changes in DTI parameters revealed nerve damage (low FA values and increased ADC) in the intraspinal canal in the Intraspinal Group, and over a widespread area in the Double-crush Group spanning the medial to lateral spinal canal. Our research suggests that in cases where double crush is suspected before surgery, failed back surgery syndrome may be prevented by evaluating DTI images.

Lower Lumbar Segmental Arteries Can Intersect Over the Intervertebral Disc in the Oblique Lateral Interbody Fusion Approach With a Risk for Arterial Injury: Radiological Analysis of Lumbar Segmental Arteries by Using Magnetic Resonance Imaging.

Study Design. A retrospective radiological study on vascular anatomy. Objective. The aim of this study was to evaluate the anatomical and radiological features of lumbar segmental arteries with respect to the surgical field of the oblique lateral interbody fusion (OLIF) approach by using magnetic resonance imaging (MRI). Summary of Background Data. OLIF surgery restores disc height and enables indirect decompression of narrowed spinal canals through an oblique lateral approach to the spine, by using a specially designed retractor. In a minimal surgical field, injuring segmental arteries can cause massive hemorrhage. Methods. We reviewed 272 lumbar MRIs. In the sagittal images, the intersection of one-third of the anterior and median lines of the intervertebral disc (IVD) was considered the center of the virtually installed OLIF retractor. The cephalad/caudal distances from the center and branch angles of segmental arteries to the longitudinal axes of the aorta were measured to determine whether the segmental arteries run into the surgical area. Statistical significance was set at P < 0.05. Results. The branch angles of segmental arteries were significantly acute (⩽90°) in L1–L3 arteries and significantly blunt (>90°) in L4 and L5 arteries. The average distance to the center of the caudal adjacent IVD was significantly larger, and there were generally low possibilities for the existence of segmental arteries below half of the vertebral height, where the surgeons can install fixation pins with ease and safety. Among the lumbar segmental arteries, L5 showed specific characteristics with significant deviation, a four times (4.1% vs. L1–L3 segmental arteries) higher adjacency rate, and a two-fifth (38.6% vs. 100%) lower existence rate. Conclusion. Segmental arteries can be involved in the surgical field of OLIF especially in the lower lumbar spine level of L4 and L5 arteries, which can directly run across IVDs. L5 segmental arteries can also be iliolumbar arteries that have an abnormal trajectory by nature. Level of Evidence: 4

Discrimination between Lumbar Intraspinal Stenosis and Foraminal Stenosis using Diffusion Tensor Imaging Parameters: Preliminary Results

Study Design Retrospective observational study. Purpose To examine fractional anisotropy (FA) values and apparent diffusion coefficient (ADC) values of damaged nerves to discriminate between lumbar intraspinal stenosis (IS) and foraminal stenosis (FS) using diffusion tensor imaging (DTI) Overview of Literature It is important in the selection of surgical procedure to discriminate between lumbar IS and FS, but such discrimination is difficult. Methods There were 9 cases of IS, 7 cases of FS, and 5 healthy controls. The regions of interest were established in the lumbar intraspinal zone (Iz), nerve root (N), and extraforaminal zone (Ez). The FA and ADC values were measured on the affected and unaffected sides of the nerves. The FA ratio and the ADC ratio were calculated as the affected side/unaffected side ×100 (%). Results In the Ez, the FA value was significantly lower in FS than in IS (p<0.01). FA ratio was significantly lower in FS than in IS for the Ez (p<0.01). In the Iz, the ADC value was significantly higher in IS than FS (p<0.01). ADC ratio was significantly higher in FS than in IS for the N and Ez (p<0.05). For the Ez, receiver operating characteristic analysis of parameters revealed that the FA values showed a higher accuracy for the diagnosis of FS than the ADC values, and the FA value cut-off value was 0.42 (sensitivity: 85.7%, false positive: 11.1%) and the FA ratio cut-off value was 83.9% (sensitivity: 85.7%, false positive: 22.2%). Conclusions The low FA value in the extraforaminal zone suggests the presence of foraminal stenosis. When the FA value and FA ratio cut-off value were established as 0.42 and 83.9%, respectively, the accuracy was high for the diagnosis of foraminal stenosis. It may be possible to use DTI parameters to help in the discrimination between IS and FS.

Does Discontinuing Teriparatide Treatment and Replacing It with Bisphosphonate Maintain the Volume of the Bone Fusion Mass after Lumbar Posterolateral Fusion in Women with Postmenopausal Osteoporosis

Study Design Retrospective case series. Purpose The purpose of this study was to determine whether discontinuing teriparatide treatment and replacing it with bisphosphonate treatment maintains the volume of the fusion mass after posterolateral fusion (PLF) in women with postmenopausal osteoporosis. Overview of Literature Clinical data support the efficacy of parathyroid hormone (PTH) for lumbar PLF. However, the use of PTH is limited to 2 years. Methods We treated 19 women diagnosed with osteoporosis and degenerative spondylolisthesis with teriparatide (20 µg daily subcutaneously). All patients underwent one-level instrumented PLF. Teriparatide was used during 2 months prior to surgery and more than 8 months after surgery. After discontinuing teriparatide treatment, all patients used bisphosphonate (17.5 mg risedronate weekly, oral administration). Area of the fusion mass across the transverse processes at one segment was determined on an anteroposterior radiograph at 1, 2, and 3 years after surgery. Results We followed 19 patients for 3 years. The average duration of teriparatide treatment was 11.5 months. The bone union rate was 95%. The average area of the bone fusion mass was not significantly different between the right and left sides at 1, 2, or 3 years after surgery (p>0.05). Conclusions This study showed that replacing teriparatide treatment with bisphosphonate maintained the bone fusion mass volume after PLF in women with postmenopausal osteoporosis.

Assessment of Clinical Symptoms in Lumbar Foraminal Stenosis Using the Japanese Orthopaedic Association Back Pain Evaluation Questionnaire

Objective It is important to develop an easy means of diagnosing lumbar foraminal stenosis (LFS) in a general practice setting. We investigated the use of the Japanese Orthopaedic Association Back Pain Evaluation Questionnaire (JOABPEQ) to diagnose LFS in symptomatic patients. Methods Subjects included 13 cases (mean age, 72 years) with LFS, and 30 cases (mean age, 73 years) with lumbar spinal canal stenosis (LSCS) involving one intervertebral disc. The visual analogue scale score for low back pain and leg pain, the JOABPEQ were evaluated. Results Those with LFS had a significantly lower JOA score (p<0.001), while JOABPEQ scores (p<0.05) for lumbar dysfunction and social functioning impairment (p<0.01) were both significantly lower than the scores in LSCS. The following JOABPEQ questionnaire items (LFS vs. LSCS, p-value) for difficulties in: sleeping (53.8% vs. 16.6%, p<0.05), getting up from a chair (53.8% vs. 6.6%, p<0.001), turning over (76.9% vs. 40%, p<0.05), and putting on socks (76.9% vs. 26.6%, p<0.01) such as pain during rest, and signs of intermittent claudication more than 15 minutes (61.5% vs. 26.6%, p<0.05) were all significantly more common with LFS than LSCS. Conclusion Results suggest that of the items in the JOABPEQ, if pain during rest or intermittent claudication is noted, LFS should be kept in mind as a cause during subsequent diagnosis and treatment. LFS may be easily diagnosed from LSCS using this established patient-based assessment method.

Efficacy of Anti-NaV1.7 Antibody on the Sensory Nervous System in a Rat Model of Lumbar Intervertebral Disc Injury

Purpose The pathophysiology of discogenic low back pain is not fully understood. Tetrodotoxin-sensitive voltage-gated sodium (NaV) channels are associated with primary sensory nerve transmission, and the NaV1.7 channel has emerged as an analgesic target. Previously, we found increased NaV1.7 expression in dorsal root ganglion (DRG) neurons innervating injured discs. This study aimed to examine the effect of blocking NaV1.7 on sensory nerves after disc injury. Materials and Methods Rat DRG neurons innervating the L5/6 disc were labeled with Fluoro-Gold (FG) neurotracer. Twenty-four rats underwent intervertebral disc puncture (puncture group) and 12 rats underwent sham surgery (non-puncture group). The injury group was divided into a saline infusion group (puncture+saline group) and a NaV1.7 inhibition group, injected with anti-NaV1.7 antibody (puncture+anti-NaV1.7 group); n=12 per group. Seven and 14 days post-surgery, L1 to L6 DRGs were harvested and immunostained for calcitonin gene-related peptide (CGRP) (an inflammatory pain marker), and the proportion of CGRP-immunoreactive (IR) DRG neurons of all FG-positive neurons was evaluated. Results The ratio of CGRP-IR DRG neurons to total FG-labeled neurons in the puncture+saline group significantly increased at 7 and 14 days, compared with the non-puncture group, respectively (p<0.05). Application of anti-NaV1.7 into the disc significantly decreased the ratio of CGRP-IR DRG neurons to total FG-labeled neurons after disc puncture at 7 and 14 days (40% and 37%, respectively; p<0.05). Conclusion NaV1.7 antibody suppressed CGRP expression in disc DRG neurons. Anti-NaV1.7 antibody is a potential therapeutic target for pain control in patients with lumbar disc degeneration.

Low-Dose Tramadol and Non-Steroidal Anti-Inflammatory Drug Combination Therapy Prevents the Transition to Chronic Low Back Pain

Study Design Retrospective study. Purpose To determine whether low-dose tramadol plus non-steroidal anti-inflammatory drug combination therapy could prevent the transition of acute low back pain to chronic low back pain. Overview of Literature Inadequately treated early low back pain transitions to chronic low back pain occur in approximately 30% of affected individuals. The administration of non-steroidal anti-inflammatory drugs is effective for treatment of low back pain in the early stages. However, the treatment of low back pain that is resistant to non-steroidal anti-inflammatory drugs is challenging. Methods Patients who presented with acute low back pain at our hospital were considered for inclusion in this study. After the diagnosis of acute low back pain, non-steroidal anti-inflammatory drug administration was started. Forty patients with a visual analog scale score of >5 for low back pain 1 month after treatment were finally enrolled. The first 20 patients were included in a non-steroidal anti-inflammatory drug group, and they continued non-steroidal anti-inflammatory drug therapy for 1 month. The next 20 patients were included in a combination group, and they received low-dose tramadol plus non-steroidal anti-inflammatory drug combination therapy for 1 month. The incidence of adverse events and the improvement in the visual analog scale score at 2 months after the start of treatment were analyzed. Results No adverse events were observed in the non-steroidal anti-inflammatory drug group. In the combination group, administration was discontinued in 2 patients (10%) due to adverse events immediately following the start of tramadol administration. At 2 months, the improvement in the visual analog scale score was greater in the combination group than in the non-steroidal anti-inflammatory drug group (p<0.001). Conclusions Low-dose tramadol plus non-steroidal anti-inflammatory drug combination therapy might decrease the incidence of adverse events and prevent the transition of acute low back pain to chronic low back pain.

Efficacy of TachoSil, a Fibrin-Based Hemostat, for Anterior Lumbar Spine Surgery

Study Design Retrospective case series. Purpose To examine the efficacy of TachoSil for vessel injury in 6 patients who underwent anterior lumbar fusion surgery (ALF). Overview of Literature ALF for the lumbar spine has a high rate of success, although intraoperative concerns and iatrogenic complications are known, and injury of a major vessel is sometimes a complication. The efficacy of TachoSil, a fibrin-based hemostat, has been reported for several types of surgery; however, use of TachoSil for ALF surgery has not been described. Here, we report on the efficacy of TachoSil in 6 patients, who underwent ALF after vascular surgeons having difficulty in repairing vessels. Methods Two man and 4 women with average age of 50.8±10.9 (mean±standard deviation) were diagnosed with a vertebral tumor (2 patients), L4 degenerative spondylolisthesis (2 patients), and L5 spondylolytic spondylolisthesis (2 patients) and underwent ALF. The blood vessels injured included the common iliac vein in 2 patients and a branch of a segmental artery from the aorta in 4 patients. We consulted a vascular surgeon to suture or repair the vessels during surgery, and although the vascular surgeon attempted to address the injuries, suturing or repair was not possible in these cases. For this reason, we used TachoSil to repair the injury in the vessels walls or to stop the bleeding. Results Time to pressure hemostasis using TachoSil was 34±12 minutes, and total blood loss was 1,488±1,711 mL. Nevertheless, all vessel injuries were controlled by the use of TachoSil. Conclusions We recommend the use of TachoSil for vessel injuries that vascular surgeons cannot suture or repair during ALF surgery.

Classification of Chronic Back Muscle Degeneration after Spinal Surgery and Its Relationship with Low Back Pain

Study Design Retrospective case series. Purpose To classify back muscle degeneration using magnetic resonance imaging (MRI) and investigate its relationship with back pain after surgery. Overview of Literature Back muscle injury and degeneration often occurs after posterior lumbar surgery, and the degeneration may be a cause of back pain. However, the relationship between back muscle degeneration and back pain remains controversial. Methods A total of 84 patients (average age, 65.1 years; 38 men, 46 women) with lumbar spinal stenosis underwent posterior decompression surgery alone. MRI (1.5 tesla) was evaluated before and more than a year after surgery in all patients. Muscle on MRI was classified into three categories: low intensity in T1-weighted imaging, high intensity in T2-weighted imaging (type 1), high intensity in both T1- and T2-weighted images (type 2), and low intensity in both T1- and T2-weighted imaging (type 3). The prevalence of the types and their relationship with back pain (determined on a visual analog scale) were evaluated. Results MRI revealed muscle degeneration in all patients after surgery (type 1, 6%; type 2, 82%; and type 3, 12%). Type 2 was significantly more frequent compared with types 1 and 3 (p<0.01). Low back pain was significantly improved after surgery (p<0.01). Low back pain was not associated with any MRI type of muscle degeneration after surgery (p>0.05). Conclusions Various pathologies of back muscle degeneration after posterior lumbar surgery were revealed. Type 2 (fatty) change was most frequent, and other patients had type 3 (scar) or type 1 (inflammation or water-like) changes. According to the Modic classification of bone marrow changes, Modic type 1 change is associated with inflammation and back pain. However, no particular type of back muscle degeneration was correlated with back pain after surgery.