Anatomical evaluation of lumbar nerves using diffusion tensor imaging and implications of lateral decubitus for lateral transpsoas approach.

PURPOSE: Recently, lateral interbody fusion (LIF) has become more prevalent, and evaluation of lumbar nerves has taken on new importance. We report on the assessment of anatomical relationships between lumbar nerves and vertebral bodies using diffusion tensor imaging (DTI). METHODS: Fifty patients with degenerative lumbar disease and ten healthy subjects underwent DTI. In patients with lumbar degenerative disease, we studied nerve courses with patients in the supine positions and with hips flexed. In healthy subjects, we evaluated nerve courses in three different positions: supine with hips flexed (the standard position for MRI); supine with hips extended; and the right lateral decubitus position with hips flexed. In conjunction with tractography from L3 to L5 using T2-weighted sagittal imaging, the vertebral body anteroposterior span was divided into four equally wide zones, with six total zones defined, including an anterior and a posterior zone (zone A, zones 1-4, zone P). We used this to characterize nerve courses at disc levels L3/4, L4/5, and L5/S1. RESULTS: In patients with degenerative lumbar disease, in the supine position with hips flexed, all lumbar nerve roots were located posterior to the vertebral body centers in L3/4 and L4/5. In healthy individuals, the L3/4 nerve courses were displaced forward in hips extended compared with the standard position, whereas in the lateral decubitus position, the L4/5 and L5/S nerve courses were displaced posteriorly compared with the standard position. CONCLUSIONS: The L3/4 and L4/5 nerve roots are located posterior to the vertebral body center. These were found to be offset to the rear when the hip is flexed or the lateral decubitus position is assumed. The present study is the first to elucidate changes in the course of the lumbar nerves as this varies by position. The lateral decubitus position or the position supine with hips flexed may be useful for avoiding nerve damage in a direct lateral transpsoas approach. Preoperative DTI seems to be useful in evaluating the lumbar nerve course as it relates anatomically to the vertebral body.

Efficacy of nerve growth factor antibody in a knee osteoarthritis pain model in mice.

BACKGROUND: Nerve growth factor (NGF) is not only an important factor in nerve growth but also a major contributor to the production of inflammation. It has been reported that inhibiting NGF could reduce several types of pain in several animal models. Here, we aimed to clarify the efficacy of NGF antibody in a knee osteoarthritis (OA) pain model in mice. METHOD: Six-week-old male C57BR/J mice were used (n = 30). Ten mice comprised the control group, which received saline injection into the right knee joints; the other 20 mice comprised the experimental group, which received monoiodoacetate (MIA) injection into the right knee joints. Three weeks after surgery, the 20 experimental mice were randomly placed into treatment groups which received either sterile saline (non-treat group: 10 mg/kg, i.p.) or an anti-NGF antibody (anti-NGF group: 10 mg/kg, i.p.). Simultaneously, all mice received fluorogold (FG) retrograde neurotracer injection into their right joints. In a behavioral study, we evaluated gait using the CatWalk quantitative gait analysis system before surgery, 3 weeks after surgery (before treatment), 4 weeks after surgery (one week after surgery), and 5 weeks after surgery (2 weeks after surgery). In immunohistochemical analysis, the right dorsal root ganglia (DRGs) from the L4-L6 levels were resected 5 weeks after surgery (2 weeks after surgery). They were immunostained for calcitonin gene-related peptide (CGRP), and the number of FG-labeled or CGRP-immunoreactive (IR) DRG neurons was counted. RESULTS: On gait analysis using the CatWalk system, duty cycle, swing speed, and print area were decreased in non-treat group compared with those in control group and improved in the anti-NGF group compared with those in non-treat group. CGRP expression in DRGs was up-regulated in non-treat group compared with that in control group and suppressed in the anti-NGF group compared with that in non-treat group (both p < 0.05). CONCLUSIONS: MIA injection into the knee joint induced gait impairment and the up-regulation of CGRP in DRG neurons in a knee OA pain model in mice. Intraperitoneal injection of anti-NGF antibody suppressed this impairment of gait and up-regulation of CGRP in DRG neurons. These finding suggest that anti-NGF therapy might be valuable in the treatment of OA pain in the knee.

Muscle injury in rats induces upregulation of inflammatory cytokines in injured muscle and calcitonin gene-related peptide in dorsal root ganglia innervating the injured muscle.

INTRODUCTION: In this study we evaluated the relationships among the behavioral changes after muscle injury, histological changes, changes in inflammatory cytokines in the injured muscle, and changes in the sensory nervous system innervating the muscle in rats. METHODS: We established a model of muscle injury in rats using a dropped weight. Behavior was assessed using the CatWalk system. Subsequently, bilateral gastrocnemius muscles and dorsal root ganglia (DRGs) were resected. Muscles were stained with hematoxylin and eosin, and inflammatory cytokines in injured muscles were assayed. DRGs were immunostained for calcitonin gene-related peptide (CGRP). RESULTS: Changes of behavior and upregulation of inflammatory cytokines in injured muscles subsided within 2 days of injury. Repaired tissue was observed 3 weeks after injury. However, upregulation of CGRP in DRG neurons continued for 2 weeks after injury. CONCLUSION: These findings may explain in part the pathological mechanism of persistent muscle pain. Muscle Nerve 54: 776-782, 2016.

Single Intradiscal Administration of the Tumor Necrosis Factor-Alpha Inhibitor, Etanercept, for Patients with Discogenic Low Back Pain.

OBJECTIVE: To examine the analgesic effect of intradiscal administration of a tumor necrosis factor-αα (TNF-α) inhibitor in patients with discogenic low back pain (LBP). DESIGN: Prospective, randomized study. SETTING: Department of Orthopaedic Surgery, Chiba (Japan) University Hospital. SUBJECTS: Seventy-seven patients diagnosed with discogenic LBP. METHODS: Discogenic LBP patients were randomly assigned to the etanercept (n = 38; bupivacaine [2 mL] with etanercept [10 mg]) or control (n = 39; bupivacaine [2 mL]) groups. Patients received a single intradiscal injection. Numerical rating scale (NRS) scores for LBP at baseline, 1 day, and 1, 2, 4, and 8 weeks after the injection were recorded. The Oswestry disability index (ODI) scores at baseline and at 4 and 8 weeks after injection were evaluated. Postinjection complications were recorded and evaluated. RESULTS: In the etanercept group, the NRS scores were significantly lower than in the control group at every time point after the injection for 8 weeks (P < 0.05). Similarly, 4 weeks after the injection, the ODI score was lower in the etanercept group than in the control group (P < 0.05). However, the ODI scores were not significantly different at 8 weeks. Complications were not observed. CONCLUSIONS: Single intradiscal administration of a TNF-α inhibitor can alleviate intractable discogenic LBP for up to 8 weeks. TNF-α may be involved in discogenic pain pathogenesis. This procedure is a novel potential treatment; longer-term effectiveness trials are required in the future.

Single intradiscal injection of the interleukin-6 receptor antibody tocilizumab provides short-term relief of discogenic low back pain; prospective comparative cohort study.

BACKGROUND: Inflammatory cytokines, such as interleukin-6 and tumor necrosis factor-α, are gaining attention as important etiologic factors associated with discogenic low back pain. We conducted a prospective cohort study to evaluate the efficacy and safety of intradiscal injection of the interleukin-6 receptor antibody tocilizumab in patients with discogenic low back pain. METHODS: Thirty-two consecutive patients were intradiscally injected with 2 mL of 0.5% bupivacaine (control group). Another 31 consecutive patients were intradiscally injected with 40 mg tocilizumab and 1-2 mL of 0.5% bupivacaine (tocilizumab group) at the same time. Prior to treatment, the vertebral origin of low back pain was confirmed in all patients based on pain provocation during discography and pain relief with 1 mL of 1% xylocaine. Numeric rating scale and Oswestry disability index scores were used to evaluate pain level before and after treatment between the 2 groups. The association between pain relief with tocilizumab and intervertebral disc degeneration grade was also determined. RESULTS: At the end of the study (8 weeks after treatment), 30 patients in each group were evaluable. In the tocilizumab group, numeric rating scale and Oswestry disability index scores improved significantly at 2 and 4 weeks after treatment, respectively. Intervertebral disc degeneration was not associated with improvement of numeric rating scale score in the tocilizumab group. Local infection (i.e., discitis) was observed in 1 patient in the tocilizumab group. CONCLUSIONS: The results demonstrate the clinical relevance of interleukin-6 in discogenic low back pain. Intradiscal tocilizumab injection was shown to exert a short-term analgesic effect in patients with discogenic low back pain. Further research is required to determine the long-term effects of intradiscal tocilizumab therapy in patients with discogenic low back pain.

Anti-RANKL antibodies decrease CGRP expression in dorsal root ganglion neurons innervating injured lumbar intervertebral discs in rats.

PURPOSE: Nuclear factor-κB (NF-κB), receptor activator of NF-κB (RANK), and RANK ligand (RANKL) are transcriptional regulators of inflammatory cytokines. RANKL expression in dorsal root ganglion (DRG) neurons is elevated in animal models of pain or intervertebral disc herniation. We sought to evaluate the effect of anti-RANKL antibodies on sensory nerves innervating injured intervertebral discs. METHOD: We labeled DRG neurons innervating L5-6 discs with FluoroGold (FG). The L5-6 discs of 36 rats were punctured using a 23-gage needle and 18 rats underwent sham surgery without disc puncture. The puncture group was evenly subdivided into a group in which 10 µl saline was administered to the injured disc and a group in which 10 µl of anti-RANKL antibody was administered. Seven and 14 days postsurgery, DRGs at L2 level were harvested, sectioned, and immunostained for calcitonin gene-related peptide (CGRP). The proportion of CGRP-immunoreactive (IR) DRG neurons of all FG-positive neurons was determined. Amount of tumor necrosis factor (TNF)-α and interleukin(IL)-6 was measured within the intervertebral discs in each group at 7 and 14 days after surgery using an enzyme-linked immunosorbent assay (ELISA). RESULTS: The proportion of CGRP-IR DRG neurons to total FG-labeled neurons innervating injured intervertebral discs and amount of TNF-α and IL-6 in the injured discs in the saline control group was significantly increased compared with that found in rats from the sham surgery group (P < 0.05). However, application of anti-RANKL antibody to the injured discs significantly decreased the proportion of CGRP-IR DRG neurons to total FG-labeled neurons and amount of TNF-α and IL-6 in the injured discs (P < 0.05). CONCLUSIONS: TNF-α and IL-6 in the injured discs increased and CGRP expression increased in DRG neurons innervating injured discs, and antibodies to RANKL could suppress this increased TNF-α, IL-6, and CGRP expression. RANKL may be a therapeutic target for pain control in patients with lumbar disc degeneration.

Evaluation of behavior and expression of NaV1.7 in dorsal root ganglia after sciatic nerve compression and application of nucleus pulposus in rats.

PURPOSE: The pathomechanisms of pain resulting from lumbar disc herniation have not been fully elucidated. Prostaglandins and cytokines generated at the inflammatory site produce associated pain; however, non-steroidal anti-inflammatory drugs and steroids are sometimes ineffective in patients. Tetrodotoxin-sensitive voltage-gated sodium (NaV) channels are related to sensory transmission in primary sensory nerves. The sodium channel NaV1.7 has emerged as an attractive analgesic target. The purpose of this study was to evaluate pain-related behavior and expression of NaV1.7 in dorsal root ganglia (DRG) after combined sciatic nerve compression and nucleus pulposus (NP) application in rats. METHODS: Rats were divided into three groups and underwent either sciatic nerve compression with NP for 2 s using forceps (n = 20), sham operation with neither compression nor NP (n = 20), or no operation (controls, n = 20). Mechanical hyperalgesia was measured every second day for three weeks using von Frey filaments. NaV1.7 expression in L5 DRG was examined 7 and 14 days after surgery using immunohistochemistry. The number of neurons immunoreactive for NaV1.7 was compared among the three groups. RESULTS: Mechanical hyperalgesia was found over the 14-day observation in the nerve compression plus NP application group, but not in the sham-operated or control groups (P < 0.05). NaV1.7 expression in L5 DRG was up-regulated in the nerve compression plus NP application group, compared with sham-operated and control rats (P < 0.01). CONCLUSIONS: Our results indicate that nerve compression plus NP application produces pain-related behavior. We conclude that NaV1.7 expression in DRG neurons may play an important role in mediating pain from sciatic nerves after compression injury and exposure to NP.

L5 spinal nerve injury caused by misplacement of outwardly-inserted S1 pedicle screws.

PURPOSE: To evaluate L5 nerve root injuries caused by outwardly misplaced S1 pedicle screws. Pedicle screws remain the criterion standard for fixation of L5-S1 to correct lumbosacral instability. When inserting S1 pedicle screws, it is possible to injure the L5 nerve root if screws are inserted outwardly and the tip of the screw perforates the anterior cortex of the sacrum. Despite this risk, to our knowledge this type of injury has never been reported as a case series. METHODS: We experienced 2 cases of L5 nerve root injury caused by outwardly-inserted S1 pedicle screws. In both cases, bilateral S1 pedicle screws were inserted outwardly using a free-hand technique, and on one side, screws induced severe pain by impinging on an L5 root. Computed tomography after the selective rootgraphy of the injured nerve showed the nerve compressed laterally by screw threads in Case 1 and crushed between the screw threads and the sacral body in Case 2. RESULTS: In both cases, leg pain disappeared immediately after the infiltration of the nerve with lidocaine, but symptoms recurred within a few days in Case 1 and within an hour in Case 2. Conservative treatment of three spinal nerve infiltrations was effective in Case 1, but reinsertion of the rogue screw was necessary in Case 2. CONCLUSIONS: Surgeons should recognize that lateral inclination of S1 pedicle screws can cause L5 nerve root injury, which may require reinsertion of the screw, especially in cases where insertion is difficult because of overlapping surrounding muscle or bony tissue.

In-vivo transfection of the proopiomelanocortin gene, precursor of endogenous endorphin, by use of radial shock waves alleviates neuropathic pain.

BACKGROUND: Neuropathic pain is difficult to control and patient response to current treatment is often inadequate. Opioids have been widely used to treat a variety of pain states, but have several side effects. Endogenous opioids are clinically safe, but are not used for treatment because of rapid metabolism. However, in-vivo transfection of endogenous opioid genes could have a powerful and safe analgesic effect. The purpose of this study was to investigate the efficacy of proopiomelanocortin (POMC, a precursor of the endogenous opioid peptide ß-endorphin) gene transfer by use of radial shock waves (RSWs) in a rat neuropathic pain model. METHODS: As a neuropathic pain model, we used the Bennett chronic constriction injury (CCI) method. Immediately after CCI induction, POMC plasmid was injected into the rats' gastrocnemius muscle followed by exposure to RSW. Mechanical allodynia was measured for 4 weeks and dorsal root ganglion (DRG) neurons were sectioned and immunostained. RESULTS: ß-Endorphin blood levels and the number of ß-endorphin-immunoreactive (IR) muscle fibers increased over 28 days. ß-Endorphin overexpression caused a decrease in the number of calcitonin gene-related peptide (CGRP)-IR DRG neurons and suppressed neuropathic pain induced by CCI without causing adverse side effects. The size-distribution pattern of CGRP-IR DRG neurons shifted from small to large cells in the CCI group; however, the number of both small and large CGRP-IR cells decreased in the POMC group. CONCLUSION: POMC gene transfection alleviated allodynia and reduced CGRP expression in DRG neurons without adverse effects. CGRP is not produced in large neurons under physiologic conditions; however, in this study CGRP expression was shifted to large neurons after nerve injury. This change in cell-size distribution suggests that CGRP expression in large neurons is related to neuropathic pain. These findings suggest that POMC gene transfection using RSWs is a safe and effective treatment for neuropathic pain.

English publication rate of 3,205 abstracts presented at the Annual Meeting of the Japanese Orthopaedic Association and the Annual Research Meeting of the Japanese Orthopaedic Association.

BACKGROUND: Previous studies reported that the publication rate of abstracts presented at overseas meetings was around 50 %. The study objectives were to determine the rate of publication in English-language journals and the impact factor (IF) for all papers presented at the Annual Meeting of the Japanese Orthopaedic Association (JOA) and Annual Research Meeting of the Japanese Orthopaedic Association (JOAR), and to compare the publication rates and IFs from abstracts accepted for oral versus poster presentations. METHODS: Titles and first authors were identified for 1,676 abstracts of free papers accepted for presentation to the JOA in 2006 and 2007, and 1,529 abstracts to the JOAR from 2006 to 2008. We identified the associated journal publications by searching PubMed, and IFs were determined using the journal citation reports. The publication rates and IFs for papers accepted for oral versus poster presentations were compared using statistical analysis. RESULTS: The overall publication rate was 25.5 % from the JOA and 50 % from the JOAR. There were no significant differences in yearly publication rates, or between oral and poster presentations for each year. The average IFs for all publications from the JOA was 2.45 and that from the JOAR was 3.5. There were no significant differences in yearly IFs, or between oral and poster presentations for each year (P > 0.05). CONCLUSIONS: The rate from JOAR was similar to publication rates for abstracts presented at overseas orthopedic meetings, however, the rate from JOA was half that of publication rates for abstracts presented at overseas orthopedic meetings, indicating that JOA may provide a below average contribution of new medical data to the international scientific community. No significant difference in publication rates between oral and poster presentations were found, and this suggests a need for improvement of the review system for the annual meeting and that review scores at the meetings did not predict the publication fate of abstracts.

Efficacy of epidural administration of anti-interleukin-6 receptor antibody onto spinal nerve for treatment of sciatica.

INTRODUCTION: Interleukin-6 (IL-6) is thought to play a crucial role in the radicular pain caused by lumbar spinal stenosis. However, efficacy of inhibition of IL-6 for sciatica in patients with lumbar spinal stenosis has not been clarified. The purpose of the current study was to examine the effect of the anti-IL-6 receptor monoclonal antibody, tocilizumab, on radicular pain by its epidural administration onto spinal nerves in patients with lumbar spinal stenosis. METHODS: Sixty patients with low back and radicular leg pain caused by spinal stenosis were investigated. In 30 patients, we infiltrated 2.0 mL of lidocaine and 80 mg of tocilizumab onto the affected spinal nerve, and 2.0 mL of lidocaine and 3.3 mg of dexamethasone were used in 30 patients. Low back pain, leg pain, and leg numbness were evaluated during 1 month after spinal nerve infiltration. RESULTS: Infiltration of tocilizumab was more effective than dexamethasone for leg pain (3 days, 1, 2, and 4 weeks), low back pain (3 days, 1, 2 and 4 weeks), and leg numbness (3 days, 1 and 2 weeks). No adverse event was observed in either group. CONCLUSION: Our results indicate that the epidural administration of an anti-IL-6 receptor monoclonal antibody, tocilizumab, onto the spinal nerve produced reduction of radicular leg pain, numbness, and low back pain without adverse event. IL-6 may be one of the inducers of pain caused by spinal stenosis in humans.

Percutaneously absorbed NSAIDs attenuate local production of proinflammatory cytokines and suppress the expression of c-Fos in the spinal cord of a rodent model of knee osteoarthritis.

BACKGROUND: Nonsteroidal anti-inflammatory drugs (NSAIDs) are commonly used in clinical situations to reduce inflammation and pain. Percutaneous administration is one of the routes mainly used in Japan to deal with the pain from acute injuries, to chronic pain such as chronic low back pain and osteoarthritis (OA). There have been no studies that report the effect of percutaneous administration of NSAIDs on chronic pain in animal models. This study aimed to investigate the effect of percutaneously absorbed NSAIDs on a rodent model of OA. METHODS: OA was induced with an intra-articular injection of monoiodoacetate into the right knees (left knee was treated with saline, normal control) of female Sprague-Dawley rats. Physical evaluation, diameter, and the range of motion (ROM) of the knee joint, as well as pain-related behavior, were evaluated. Animals were killed and perfused 7 days after the intra-articular injection, and then local tissue from the knee [for cytokine assay: tumor necrosis factor (TNF)-α, interleukin (IL)-6, and nerve growth factor (NGF)] and spinal cord (immunostained for c-Fos protein reflecting neuronal excitation) were evaluated (n = 7 each). Twenty-eight days after the injection, the other rats were then divided into three groups and were identified by a plaster tape containing an NSAID or a vehicle applied to their OA (ipsilateral) knees: a vehicle-treated group, a loxoprofen-treated (lox) group, and a ketoprofen-treated (ket) group. The behavior elicited by von Frey hairs, inflammatory cytokines, and c-Fos protein at 0, 8, and 24 h after tape application were evaluated (n = 7 each). The plaster tapes contained corresponding NSAIDs used in clinical settings: lox 2.8 mg and ket 1.1 mg. Three of the OA animals were histologically evaluated. RESULTS: As the OA progressed, the ipsilateral knee joint showed OA-like appearance physically and histologically. The knee diameter increased and ROM decreased significantly (P < 0.05), showing histological OA-like cartilage degeneration. Pain threshold decreased significantly according to OA progression (P < 0.05). NSAID application significantly improved the threshold 24 h after application in both the lox and ket groups (P < 0.05) without any significant difference between groups. Cytokine concentrations and c-Fos were significantly suppressed in both lox and ket groups (P < 0.05). Lox suppressed TNF-α and NGF more than ket, whereas ket suppressed IL-6 more. CONCLUSION: Suppression of proinflammatory cytokines and c-Fos expression by clinically used NSAIDs suggests that their percutaneous administration may have an analgesic effect for treating chronic pain at a molecular level.

Improvements in Intractable Lumbar and LowerExtremity Symptoms after Systemic Administration of Tocilizumab, an Anti-interleukin-6 Receptor Antibody.

STUDY DESIGN: Prospective cohort study (open-label, single-arm, and non-blinded). PURPOSE: This study aims to determine the effects of systemic administration of tocilizumab, an anti-interleukin-6 (IL-6) receptor antibody on refractory low back pain and leg symptoms. OVERVIEW OF LITERATURE: IL-6 overexpression is associated with neuropathic pain pathogenesis, which is potentially followed by chronic low back pain, including leg pain and numbness. This finding suggest that inhibition of IL-6 at the site of pain or in the transmission pathway could provide novel therapeutic targets for chronic low back pain. METHODS: This prospective, single-arm study included 11 patients (eight men; mean age, 62.7 years) with ≥3-months' chronic pain history due to lumbar disease. Subcutaneous TCZ injections were administered twice, at a 2-week interval. We evaluated low back pain, leg pain, and leg numbness using numeric rating scales and the Oswestry Disability Index (ODI; baseline and 6 months postinjection); serum IL-6 and tumor necrosis factor-α levels (baseline and 1 month postinjection); and clinical adverse events. RESULTS: Intractable symptoms reduced after TCZ administration. Low back pain improved for 6 months. Improvements in leg pain and numbness peaked at 4 and 1 month, respectively. Improvements in ODI were significant at 1 month and peaked at 4 months. Serum IL-6 was increased at 1 month. IL-6 responders (i.e., patients with IL-6 increases >10 pg/mL) showed particularly significant improvements in leg pain at 2 weeks, 1 month, and 2 months compared with nonresponders. We observed no apparent adverse events. CONCLUSIONS: Systemic TCZ administration improved symptoms effectively for 6 months, with peak improvements at 1-4 months and no adverse events. Changing serum IL-6 levels correlated with leg pain improvements; further studies are warranted to elucidate the mechanistic connections between lumbar disorders and inflammatory cytokines.

Platelet-rich plasma enhances bone union in posterolateral lumbar fusion: A prospective randomized controlled trial.

BACKGROUND CONTEXT: Platelet-rich plasma (PRP) accelerates bone union in vivo in a rodent model of spinal fusion surgery. However, PRP's effect on bone union after spinal surgery remains unclear. PURPOSE: The objective of this study was to evaluate the efficacy of PRP after posterolateral lumbar fusion (PLF) surgery. STUDY DESIGN/SETTING: Single-center prospective randomized controlled clinical trial with 2-year follow-up. PATIENT SAMPLE: The patient sample included a total 62 patients (31 patients in the PRP group or 31 patients in the control group). OUTCOME MEASURES: The outcome measures included the bone fusion rate, the area of bone fusion mass, the duration of bone fusion, and the clinical score using the visual analog scale (VAS). MATERIALS AND METHODS: We randomized 62 patients who underwent one- or two-level instrumented PLF for lumbar degenerative spondylosis with instability to either the PRP (31 patients) or the control (31 patients) groups. Platelet-rich plasma-treated patients underwent surgery using an autograft bone chip (local bone), and PRP was prepared from patient blood samples immediately before surgery; patients from the control group underwent PLF without PRP treatment. We assessed platelet counts and growth factor concentrations in PRP prepared immediately before surgery. The duration of bone union, the postoperative bone fusion rate, and the area of fusion mass were assessed using plain radiography every 3 months after surgery and by computed tomography at 12 or 24 months. The duration of bone fusion and the clinical scores for low back pain, leg pain, and leg numbness before and 3, 6, 12, and 24 months after surgery were evaluated using VAS. RESULTS: Data from 50 patients with complete data were included. The bone union rate at the final follow-up was significantly higher in the PRP group (94%) than in the control group (74%) (p=.002). The area of fusion mass was significantly higher in the PRP group (572 mm2) than in the control group (367 mm2) (p=.02). The mean period necessary for union was 7.8 months in the PRP group and 9.8 months in the control group (p=.013). In the PRP, the platelet count was 7.7 times higher and the growth factor concentrations were 50 times higher than those found in plasma (p<.05). There was no significant difference in low back pain, leg pain, and leg numbness in either group at any time evaluated (p>.05). CONCLUSIONS: Patients treated with PRP showed a higher fusion rate, greater fusion mass, and more rapid bone union after spinal fusion surgery than patients not treated with PRP.

Longitudinal Evaluation of the Histological Changes in a Rat Model of Paravertebral Muscle Injury.

INTRODUCTION: Thus far, few reports have described the time series histological variations in injured paravertebral muscle tissues for long durations, considering the type of pain. The purpose of this study is to evaluate histological changes in injured paravertebral muscles and dominant nerves considering the type of pain. METHODS: We used 59 eight-week-old male Sprague-Dawley rats. A 115-g weight was dropped from a height of 1 m on the right paravertebral muscle. Fluoro-Gold (FG), a sensory nerve tracer, was injected into this muscle. Hematoxylin and eosin (HE) staining and nerve growth factor (NGF) immunostaining of the muscle were performed for histological evaluation. L2 dorsal root ganglia (DRG) on both sides were resected, and immunohistochemical staining was performed for calcitonin gene-related peptide (CGRP, a pain-related neuropeptide) and for activating transcription factor 3 (ATF3, a neuron injury marker). Each examination was performed at 3 days, 1-3 weeks, and 6 weeks after injury. RESULTS: HE staining of the paravertebral muscle indicated infiltration of inflammatory cells and the presence of granulation tissue in the injured part on the ipsilateral side at 3 days and 1 week after the injury. Fibroblasts and adipocytes were present at 2-3 weeks. At 6 weeks, the injured tissue was almost completely repaired. NGF was detected at 2-3 weeks post injury and appeared to colocalize with fibroblasts, but was not observed at 6 weeks post injury. The percentage of cells double-labeled with FG and CGRP in FG-positive cells of the primary muscle was significantly higher in the injured side at 3 days and 1-3 weeks post injury (P < 0.05). However, at 6 weeks, no significant difference was observed. No significant expression of ATF3 was observed. CONCLUSIONS: These results suggest that sensitization of the dominant nerve in the DRG, in which NGF may play an important role, can protract pain in injured muscles.

Vascular endothelial growth factor in degenerating intervertebral discs of rat caudal vertebrae.

INTRODUCTION: Discogenic back pain remains poorly understood with respect to etiopathogenesis, despite being a considerable burden. We sought to examine the expression of vascular endothelial growth factor in injured intervertebral discs in rat caudal vertebrae. METHODS: Forty-eight male Sprague Dawley rats were assigned to 2 groups according to disc puncture injury: puncture (n = 32) or non-puncture (n = 16). Disc puncture was performed percutaneously such that the incision would be in the primary plane of motion for the coccygeal discs 5-6, 6-7, and 7-8. A 26-gauge needle was used to puncture each disc 10 times. Punctured discs were examined histologically by hematoxylin and eosin staining at 1, 7, 14, and 28 days post-injury. RESULTS: Vascular endothelial growth factor was localized immunohistochemically, and determined quantitatively using an enzyme-linked immunosorbent assay. Peak inflammation occurred on the 7th day post-injury, but tissue degeneration continued until day 28. Local expression of vascular endothelial growth factor tended to be highest in the annulus fibrosus on the 7th and 14th days after puncture injury. The level of vascular endothelial growth factor was highest 1-day post-injury, and then gradually decreased thereafter. Furthermore, vascular endothelial growth factor levels in the puncture group were significantly higher than those in the non-puncture control group (p < 0.05). CONCLUSIONS: We found increased expression of the inflammatory cytokine vascular endothelial growth factor in injured intervertebral discs, suggesting that vascular endothelial growth factor may be clinically important in discogenic back pain.

Evaluation of Histological Changes in Back Muscle Injuries in Rats over Time.

STUDY DESIGN: Animal model study. PURPOSE: The purpose of this study was to evaluate the histological variation in the injured muscle and production of calcitonin gene-related peptide in rats over time. OVERVIEW OF LITERATURE: Vertebral surgery has been reported to cause atrophy of the back muscles, which may result in pain. However, few reports have described the time series histological variation in the injured muscle and changes in the dominant nerve. METHODS: We used 30 male, 8-week-old Sprague-Dawley rats. The right and left sides of the paravertebral muscle were considered as the injured and uninjured sides, respectively. A 115 g weight was dropped from a height of 1 m on the right paravertebral muscle. Hematoxylin and eosin (H&E) staining of the muscle was performed 1-3 weeks after injury for histological evaluation. Fluoro-Gold (FG) was injected into the paravertebral muscle. The L2 dorsal root ganglia on both sides were resected 1, 2, and 3 weeks after injury, and immunohistochemical staining for calcitonin gene-related peptide was performed. RESULTS: H&E staining of the paravertebral muscle showed infiltration of inflammatory cells and the presence of granulation tissue in the injured part on the ipsilateral side 1 week after injury. Muscle atrophy occurred 3 weeks after injury, but was repaired via spontaneous replacement of muscle cells/fibers. In contrast, compared with the uninjured side, the percentage of cells double-labeled with FG and calcitonin gene-related peptide in FG-positive cells in the dorsal root ganglia of the injured side was significantly increased at each time point throughout the study period. CONCLUSIONS: These results suggest that sensitization of the dominant nerve in the dorsal root ganglia, which may be caused by cicatrix formation, can protract injured muscle pain. This information may be helpful in elucidating the underlying mechanism of persistent pain after back muscle injury.

Oriented collagen tubes combined with basic fibroblast growth factor promote peripheral nerve regeneration in a 15 mm sciatic nerve defect rat model.

We developed a new scaffold material-oriented collagen tubes (OCT)-and evaluated the potential of OCTs combined with basic fibroblast growth factor (bFGF) to repair of a 15 mm sciatic nerve defect in rats. The treatment groups consisted of OCT with adsorbed bFGF (OCT/bFGF group), OCT in phosphate-buffered saline (PBS) (OCT/PBS group), and a no-treatment group (Defect group). Functional evaluation of nerve regeneration was performed using the CatWalk system, and histological analyses of the defect sites were also performed. In rats treated with either OCT/bFGF or OCT/PBS, the walking function parameter of max contact area returned to normal levels by 4 weeks after grafting, and the regeneration of myelinated fibers was detected after 8 weeks. However, more regenerated myelinated fibers were observed in the OCT/bFGF group compared with the OCT/PBS group at 4 weeks. In addition, the max contact area and swing speed in the OCT/bFGF group were significantly recovered compared to the OCT/PBS and Defect groups at 8 weeks. Although the combination of bFGF and OCT was superior to OCT alone for nerve regeneration and functional recovery, the present findings demonstrate that OCT alone or in combination with bFGF accelerates nerve repair in a large peripheral nerve defect in rats. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 8-14, 2017.

Inhibiting Vascular Endothelial Growth Factor in Injured Intervertebral Discs Attenuates Pain-Related Neuropeptide Expression in Dorsal Root Ganglia in Rats.

STUDY DESIGN: An experimental animal study. PURPOSE: To evaluate effects of anti-vascular endothelial growth factor (VEGF) on the content and distribution of the calcitonin gene-related peptide (CGRP) in the dorsal ganglia in a rat model. OVERVIEW OF LITERATURE: Increased expression of VEGF in degenerative disc disease increases the levels of inflammatory cytokines and nerve ingrowth into the damaged discs. In animal models, increased levels of VEGF can persist for up to 2 weeks after an injury. METHODS: Through abdominal surgery, the dorsal root ganglia (DRG) innervating L5/L6 intervertebral disc were labeled (FluoroGold neurotracer) in 24, 8-week old Sprague Dawley rats. The rats were randomly allocated to three groups of eight rats each. The anti-VEGF group underwent L5/6 intervertebral disc puncture using a 26-gauge needle, intradiscal injection of 33.3 µg of the pegaptanib sodium, a VEGF165 aptamer. The control-puncture group underwent disc puncture and intradiscal injection of 10 µL saline solution, and the sham-surgery group underwent labeling but no disc puncture. Two rats in each group were sacrificed on postoperative days 1, 7, 14, and 28 after surgery. L1-L6 DRGs were harvested, sectioned, and immunostained to detect the content and distribution of CGRP. RESULTS: Compared with the control, the percentage of CGRP-positive cells was lower in the anti-VEGF group (p<0.05; 40.6% and 58.1% on postoperative day 1, 44.3% and 55.4% on day 7, and 42.4% and 59.3% on day 14). The percentage was higher in the control group compared with that of the sham group (p<0.05; sham group, 34.1%, 40.7%, and 33.7% on postoperative days 1, 7, and 14, respectively). CONCLUSIONS: Decreasing CGRP-positive cells using anti-VEGF therapy provides fundamental evidence for a possible therapeutic role of anti-VEGF in patients with discogenic lower back pain.

Long-Term Outcomes of In Situ Fusion for Treating Dysplastic Spondylolisthesis.

STUDY DESIGN: Retrospective, observational, single-center study. PURPOSE: To investigate the long-term outcomes of in situ fusion procedures for treating dysplastic spondylolisthesis. OVERVIEW OF LITERATURE: In situ fusion performed in patients with dysplastic spondylolisthesis avoids the development of nerve complications. METHODS: In total, 12 of 28 patients who underwent in situ fusion for treating dysplastic spondylolisthesis at Chiba University Hospital from 1974 to 2004 were followed up in August 2013. Surgical complications were evaluated. Low back pain and leg pain were assessed using a visual analog scale (VAS). Vertebral alignment, including the lumbosacral angle and lumbar lordosis angle measurement on radiographic images (profile view in the neutral standing position), was evaluated during preoperative, postoperative, and final examinations. RESULTS: The mean follow-up duration, patient age at the final examination, and patient age at operation were 20.0±7.2, 42.3±13.3, and 22.3±11.4 years, respectively. No complications were reported. Mean VAS scores for low back pain and leg pain were significantly lower at the final examination than at the preoperative examination (p<0.05). At the preoperative, postoperative, and final examinations, the mean lumbosacral angle was 32.3°±14.2°, 33.7°±11.8°, and 36.5°±16.4°, while the mean lumbar lordosis angle was 51.0°±14.8°, 48.6°±18.8°, and 49.6°±15.5°, respectively. No significant differences were noted among these values across the different time periods (p<0.05). CONCLUSIONS: In situ fusion performed in patients with dysplastic spondylolisthesis avoids the development of nerve complications such as nerve paralysis that may occur after repositioning operation and maintains appropriate long-term sagittal alignment, even 20 years after operation.