We present a new hypothesis regarding the causes of chronic low back pain based on the neuroanatomy of the sensory and emotional aspects of pain. Of the neuroanatomical components involved in pain signaling, spatial discrimination is highest in the skin, lower in musculoskeletal tissue, and lowest in the lumbar spinal canal tissues. Nociceptive signaling in the lumbar intra spinal canal tissue is transmitted by sympathetic afferent fibers projecting into the deep laminae of the spinal dorsal horn. The pain experience consists of sensory and emotional aspects. Emotional components originate in the deep laminae of the spinal dorsal horn and are transmitted to and processed in the limbic system of the brain. Thus, pain sensation originating inside the lumbar spinal canal, where there is low spatial discrimination, projects relatively strongly to the emotional system of the brain, where it may lead to chronicity.

The prevalence and the associated burden of low back pain (LBP) increase with age; however, research on LBP has primarily focused on young people and adults, and little attention has been given to the elderly population. Given that older adults are susceptible to LBP, the mechanism of geriatric chronic pain remains unexplained. Senescent cells involving irreversibly proliferative arrest can develop the SASP, consisting of proinflammatory cytokines and extracellular matrix-degrading proteins, which function as deleterious paracrine and systemic mild inflammation. Chronic inflammation is well known as a senescence-associated secretory phenotype (SASP), which produces numerous proinflammatory cytokines leading to age-related inflammation ( "inflammaging" ). Age-related low muscle mass (sarcopenia) and/or intramuscular fat deposition (sarcopenic obesity), which are associated with geriatric LBP, are considered part of systemic inflammation. In sarcopenia, age-related loss of trunk muscle mass follows a decrease in skeletal muscle mass of the extremities, which leads to poor spinal sagittal balance and subsequent LBP. On the other hands, pathological changes in the posterior horn of the spinal cord and/or peripheral nerve system also adversely affect the pain sensitivity of the elderly with aging. As above, we consider that the mechanism of senescence and the development of chronic pain are closely related. However, since there are no clinically useful biomarkers for senescence in the elderly, we focused on the fact that chronic inflammation associated with senescence causes a decrease in skeletal muscle mass and an increase in fat mass. Thus, we have been addressing the research to find the body compositional changes that are indicators of the development of chronic pain in the elderly. Focusing on the skeletal muscle-fat ration from the viewpoint of the mechanism of senescence as an evaluation of the threshold of body composition that causes chronic pain in the elderly, we demonstrated that skeletal muscle mass 2.5 times the fat mass of the lower extremities should be maintained as an index of exercise therapy.

The sacroiliac joint (SIJ) functions as a shock absorber with a narrow range of motion at the base of the spine, at the interface between the trunk and lower limbs. SIJ disorders occur due to minor subluxation of the joint caused by unintentional or repetitive movements in activities of daily living. Most cases are resolved by early diagnosis with SIJ injections and early treatment including manual therapies, but chronic and severe cases may lead to a severe deterioration in quality of life. Severe cases are classified into three pathological mechanisms: 1) traumatic damage to the surrounding ligaments and joint capsule; 2) inflammation within the SIJ cavity; and 3) enthesopathy of the periarticular ligamentous bone attachment sites. Among the SIJ disorders caused by obvious traumatic accidents, some patients are susceptible to contrast medium leakage from the joint cavity, particularly young patients who may experience chronic SIJ pain due to irreversible joint maladjustment and damage to the periarticular ligaments and joint capsule caused by trauma. Prolonged subluxation of the joint may result in intra-articular inflammation, and similarly, continued excessive traction on the periarticular ligaments, such as the sacrotuberous and long posterior sacroiliac ligaments, may result in enthesopathy similar to severe plantar tendinitis. Intra-articular SIJ injections, extracorporeal shock wave therapies, and SIJ arthrodesis should be considered in severe cases.

Osteoporosis and low back pain are closely related pathologies for physicians who work in pain management. Therefore, it is very important to accurately understand the mechanisms involved from a diagnostic and therapeutic point of view. It is important to note the following: 1. Complications of spinal diseases, 2. Fractures, 3. Osteoporosis, and 4. Sarcopenia are important. Another important point is that these factors do not exist independently, and it is necessary to keep this in mind when examining and treating patients with osteoporosis and back pain.

The purpose of this study was to investigate the association between chronic low back pain (CLBP) visual analogue scale (VAS) scores and the T2 values of the discs, intramyocellular lipids (IMCL), and extramyocellular lipids (EMCL) of the multifidus and psoas muscles, spinopelvic alignment, and lumbar range of motion. The CLBP VAS score was significantly negatively correlated with the T2 value of the posterior annulus fibrosus (AF) at the L4/5 level (r=−0.49, p<0.01), significantly positively correlated with the IMCL of the multifidus muscle (r=0.51, p<0.01), significantly negatively correlated with lumbar lordosis (r=−0.41, p<0.01), and significantly positively correlated with sagittal vertical axis (r=0.42, p<0.01). Rich afferent fibers around the posterior AF at the L4/5 level, inflammation associated with increased IMCL, load on the intervertebral disc, intramuscular pressure, and muscle ischemia due to spinal kyphosis may be factors contributing to CLBP.

Low back pain is a significant problem in the world and in Japan. It is understood that about 70% of non-specific low back pain improves in 4-6 weeks, but the remaining 30% becomes chronic. It is widely known that psychosocial factors, in addition to structural and functional problems, are responsible for the chronicity and delayed improvement of non-specific low back pain. Therefore, it is necessary to consider non-specific low back pain based on a biopsychosocial model. In addition, the concepts of classification and stratified care have been developed to identify the direction of specific interventions by grouping low back pain according to its characteristics, rather than considering it as a single condition. Physical therapy management for non-specific low back pain based on the biopsychosocial model requires different strategies depending on the duration of the disease, and more multifaceted strategies are needed in the chronic phase. In recent years, a new intervention called Cognitive Functional Therapy, which is a multifaceted intervention method consisting of the three components of "Making Sense of Pain," "Exposure with Control," and "Lifestyle Change," has been proposed. Since 80% of low back pain is non-specific that does not require surgery, the evolution of physical therapy will help to decrease the number of low back pain patients.

Introduction: Factors affecting program efficacy and subjective improvement in patients with chronic low back pain who participated in an outpatient pain management program combining education and exercise were investigated.

Methods: The subjects were 83 participants in this program who had chronic low back pain lasting more than 3 months. Education and exercise therapy were combined and conducted in small groups, one day a week, for a total of nine sessions. Before and after the program, Visual Analog Scale (VAS), Pain Disability Assessment Scale (PDAS), Hospital Anxiety and Depression scale (HADS), Pain Catastrophizing Scale (PCS), Pain Self-Efficacy Questionnaire (PSEQ), EuroQol 5 Dimension (EQ-5D), 6-min walk distance, and isometric trunk muscle strength were assessed, and subjective improvement was rated on a 7-point scale at the end of the program. The analysis consisted of 1) comparison of each evaluation item before and after the program, and 2) multiple regression analysis with subjective improvement as the dependent variable and the rate of change in other evaluation items as the independent variable.

Results: Significant improvements were observed in VAS, PDAS, HADS, PCS, PSEQ, EQ-5D, 6-min walk distance, and isometric trunk muscle strength after the program. In addition, PCS, 6-min walk distance, and EQ-5D were identified as factors affecting subjective improvement.

Conclusions: The results suggest that catastrophizing, exercise tolerance, and quality of life may have a strong effect on subjective improvement in patients with chronic low back pain.

Sacroiliac joint (SIJ) dysfunction has been recognized as one of the major causes of low back and buttock pain. Conservative treatments are effective in most patients with SIJ pain due to dysfunction. However, some intractable cases require surgical treatment. Currently, various types of SIJ arthrodesis with minimally-invasive techniques are performed for numerous patients in the USA and Europe, and many surgeons have realized that dealing with SIJ problems could become part of their responsibilities. The most important factor that determines the postoperative outcome is the definitive diagnosis of SIJ dysfunction. According to the diagnostic algorithm of the Japanese Sacroiliac Joint Research Association, the diagnosis of SIJ pain is confirmed when there is more than 70% pain relief after a diagnostic SIJ injection. For minimally-invasive sacroiliac joint fixation, the iFUSE Implant System^® (SI-BONE, Inc., San Jose, CA, USA) is most commonly used in the USA and Europe, and it has been reported to have good results. In a pilot study conducted in Japan, the implant system was found to be superior in terms of simplicity and the minimal invasiveness of the surgical procedure. However, there is a risk of pelvic vascular/nerve injury due to the lateral approach, and long-term results may be unstable in elderly women due to loosening of the implant on the sacral side. Minimally-invasive revision surgery using the same lateral approach is difficult when the implant loosens, so surgery should be performed only for carefully selected cases.

A deficiency in lumbar muscle blood circulation is considered to be a major risk factor for nonspecific low back pain. The aim of this study was to investigate changes in relative circulation over time in the lumbar multifidus in different sitting positions between subjects with and without LBP.

Ten subjects (mean age, 21.0 years) with low back pain (LBP group) for the past three months and ten healthy subjects (mean age, 21.1 years) without low back pain (non-LBP group) for the past twelve months were recruited. They received a full explanation, and all agreed to participate in this study. Near-infrared spectroscopy (NIRS) was used to non-invasively measure total hemoglobin (Total-Hb), oxygenated hemoglobin (Oxy-Hb), and deoxygenated hemoglobin (Deoxy-Hb) of the lumbar multifidus at the L5-S1 segment. All measurements were obtained in the neutral position, at 30 degrees of trunk flexion, and at 20 degrees of trunk extension while sitting. The subjects were asked to move into either the flexed or extended position from the starting (neutral) position in 3 seconds timed by a metronome and to maintain the positions for 60 seconds. The angles of the flexed and extended positions were measured with goniometer, and self-made devices were used to properly maintain these positions. All participants received education and practice time in order to be able to perform the proper body movements and positions prior to assessment. The measurements were obtained at -3 seconds (neutral position), 0, 30, and 60 seconds in each flexed and extended position while sitting and compared between subjects of the LBP and non-LBP groups.

In flexion, significant interactions were observed with Total-Hb and Deoxy-Hb of lumbar multifidus. There was no significant difference in the changes over time in the LBP group. However, in the non-LBP group, significant decreases were noted in all Total-Hb, Oxy-Hb, and Deoxy-Hb. In extension, significant interactions were observed with the Total-Hb and Oxy-Hb of lumbar multifidus. There were no significant differences in the changes over time in the non-LBP group. However, in the LBP group, significant increases were noted in Total-Hb, Oxy-Hb, and Deoxy-Hb.

The results of this study showed that the intramuscular circulation of lumbar multifidus decreased in the non-LBP group once the trunk started moving into the flexed position on sitting, but there was no change in the LBP group. On the other hand, the intramuscular circulation of lumbar multifidus increased once the trunk started moving into the extended position in the LBP group; however, there was no change in the non-LBP group.

Introduction: Removal of intradural extramedullary spinal cord tumors in thoracolumbar spine with total or partial laminectomy has been extensively utilized; however, new neurological symptoms often develop. Motor evoked potential (MEP) monitoring during surgery has been found to be useful for decreasing postoperative neurological complications in the prediction of postoperative neurological complications. Therefore, use of multimodality intraoperative monitoring, including MEP monitoring for surgery has been recommended. This study aimed to investigate the prognosis of new-onset or worsening neurological symptoms following the removal of intradural extramedullary tumors in the thoracolumbar spine on MEP monitoring.

Method: Fifty-five patients (29 men, and 26 women; mean age, 61.8 years: mean follow-up duration, 33.1 months) who had undergone removal of intradural extramedullary tumors in the thoracolumbar spine at our hospital between January 2006 and September 2019 were retrospectively reviewed. Transcranial electrical stimulation was used for MEP monitoring of all patients. Data pertaining to age, sex, follow-up duration, histology, location, and neurological deficits from the medical charts of these patients were reviewed. New-onset or worsening neurological symptoms included motor and sensory deficit and bladder dysfunction.

Results: The histopathological diagnoses were schwannomas in 35 patients, meningioma in 17, ependymoma in 1, epidermoid tumor in 1, hemangioma in 1, and glomus tumor in 1. New-onset or worsening neurological symptoms were observed in 19 patients (34.5%) after the surgery; 17 patients exhibited a new-onset sensory disorder, 3 had a worsening motor deficit, and 3 had new-onset bladder dysfunction. In the patient who developed postoperative bladder dysfunction, the tumor was localized to the ventral side of the conus medullaris. The MEP amplitude of all three patients did not decrease by >50% from that observed at baseline.

Conclusion: The present study demonstrated that the incidence of new-onset or worsening neurological symptoms after the removal of intradural extramedullary tumors was 34.5% on MEP monitoring. Three patients had new-onset bladder dysfunction. Care should be taken when treating the ventral side tumor of the conus medullaris.

Introduction: This study aimed to evaluate the effect of lumbar function by the number of decompression levels on postoperative lumbar function.

Methods: Between May 2017 and April 2019, 291 consecutive patients who were diagnosed with lumbar spinal canal stenosis and underwent microscopic posterior decompression surgery at our institution were included in this study. Patients (n = 170) who underwent single-level lumbar decompression were categorized into the S group, while patients (n = 121) who underwent multi-level lumbar decompression were categorized into the M group. The Japanese Orthopaedic Association score, Japanese Orthopaedic Association Back Pain Evaluation Questionnaire (JOABPEQ), and visual analogue scale of low back pain were used to measure operative outcomes, and the scores of the groups were compared. The Mann-Whitney U-test was performed and Spearman's rank correlation coefficient was determined.

Results: The S group had significantly higher scores than the M group for postoperative lumbar spine dysfunction, walking ability, social life dysfunction, mental health on the JOABPEQ subscales, and amount of change in these scores. Significant correlations were observed between the number of decompression levels and walking ability on the JOABPEQ subscales.

Conclusions: We should readily perform multi-level lumbar decompression to prevent reoperation at other levels of the primary surgery. However, multilevel lumbar decompression surgery affects the lumbar function. Therefore, to prevent postoperative deterioration of lumbar spine function and low back pain, the age, affected levels, and spinal canal area, must be considered for each case, and appropriate decompression levels must be determined.

Introduction: We have introduced unilateral thigh-raising exercises combined with bilateral arm maximum elevation in a sitting position as specific isometric exercises of core trunk muscles at an early stage after lumbar surgery. The aim of the present study was to determine the effects of bilateral arm elevation on core muscle activity during our postoperative exercises using surface electromyography.

Methods: Ten healthy young volunteers were included. The activities of 3 trunk muscles, the external oblique (EO), internal oblique (IO), and lumbar spine erector muscles (LE), were measured bilaterally. The participants performed 4 types of exercises in a sitting position: unilateral thigh-raising on the side ipsilateral to the measurement (Ex1); additional bilateral arm maximum elevation, coupled with Ex1 (Ex2); thigh raising on the contralateral side (Ex3); and bilateral arm elevation, coupled with Ex3 (Ex4). Integrated rectified waveform (iEMG) values were measured per second in each muscle bilaterally during stable muscle contraction in each exercise. The changes in the iEMG values during the exercises from those measured while the participant was sitting were determined.

Results: Increases of EO and IO muscle activities were significantly greater in Ex2 than in Ex1. In contrast, there were no changes in LE muscle activities during all 4 types of exercises.

Conclusions: These findings suggest that additional bilateral arm maximum elevation during unilateral thigh-raising exercise could be a useful method to enhance EO and IO muscle activity without changing LE muscle activity. Thus, our postoperative exercise program was considered an appropriate method by which to increase trunk stability through promoting core muscle activity without a load on the back extensors at an early stage after lumbar posterior decompression surgery.

INTRODUCTION: The endplate-intervertebral disc (IVD) complex is closely interrelated with the vertebral body (VB) in the structural integrity of the anterior spinal column, including biomechanical and biological functions. Our previous study showed that endplate and intervertebral disc injuries occurred frequently with osteoporotic vertebral fractures (OVFs), and these injuries were not significant independent risk factors of delayed union at six months after injury. However, the impact of these injuries on the other important outcome of OVF treatment, vertebral collapse assessment, was not determined. The purpose of this study was to elucidate the association of endplate and/or IVD injuries with the progression of vertebral collapse by semi-quantitative assessment.

METHODS: Endplate and IVD injuries associated with single- and acute-OVFs were retrospectively evaluated using magnetic resonance imaging (MRI). The vertebrae of 72 patients (male: 13, female: 59, mean age: 79.5 years) who received conservative treatment for at least 6 months were included in this study. Using the lateral view of the plain radiograph in the sitting position, anterior (A), center (C), and posterior (P) vertebral collapse was evaluated by a semi-quantitative technique at baseline and six months after injury. The progression of vertebral collapse was classified by semi-quantitative grade at 6 months compared to baseline and classified into two groups (advanced collapse group/no advanced collapse group) To identify factors that impact vertebral collapse, statistical analyses were performed.

RESULTS: Overall, 13 of 72 patients were in the advanced collapse group. Progression of vertebral collapse occurred more frequently in the case of OVFs with IVD injuries (10 of 51 patients: 20%) or EP injuries (8 of 42 patients: 19%) compared with cases without IVD/EP injury (1 of 14 patients: 7%). However, these factors were not significantly associated with the progression of vertebral collapse. The other patient characteristics at baseline (age, sex, level of fracture) were also not significantly associated with the progression of vertebral collapse in this study.

DISCUSSION: The endplate and IVD injuries in OVFs were not significantly associated with the progression of vertebral collapse using semi-quantitative assessment. To evaluate the impact of endplate and/or IVD injuries on OVF treatment outcomes comprehensively, a pain scale and health-related quality of life should also be examined in a future study.

Introduction: Condoliase reduces the pressure of lumbar disc herniation and ameliorates pain. But the timing of its onset is vague. The purpose of this study was to elucidate and predict the improvement after condoliase injection.

Methods: We conducted a retrospective study using Oswestry Disability Index (ODI) at pre-injection and post-injection (1, 4 and 12 weeks).

Results: A total of 48 patients completed the questionnaire. The results showed an improvements with time. Minimal clinically important differences were achieved in 27% of the patients at week 1, 50% at week 4, and 75% at week 12. The earlier and later improvements were fitted by linear regression and the correlation coefficients were 0.51 in 1-4 weeks, 0.42 in 1-12 weeks, and 0.72 in 4-12 weeks.

Conclusion: we showed that post-injection ODI change is predictable, with the greatest correlation coefficient between 4-12 weeks.

Introduction: Lumbar spondylolysis refers to a stress fracture that is commonly observed in adolescents involved with sports activities. Early diagnosis and treatment result in satisfactory healing in many patients. Although recurrence is known to occur in a few cases, accurate data regarding recurrence rates remain unknown. In this study, we investigated the prognosis of post-recovery lumbar spondylolysis in adolescents.

Methods: A total of 108 patients under the age of 18 years who were diagnosed with lumbar spondylolysis and had bone fusion were included in the study. A post-treatment questionnaire was administered by telephone and paper.

Results: We received a response from 64 of 108 patients (response rate 59%). Recurrent low back pain (LBP) occurred in 28 of 64 (44%) patients. The recurrence of low back pain tended to be more common in females, L3 by height of lumbar spondylolysis, "fresh/old" by morbidity type, and advanced stage by CT classification, but there was no significant difference. MRI and CT were performed on 11 patients who had recurrent low back pain, and recurrence of lumbar spondylolysis was found in 3 patients (27%).

Conclusions: We conducted a questionnaire-based prognostic survey of patients with lumbar spondylolysis who had bone fusion and found that 44% had recurrent back pain. Of these, recurrence of lumbar spondylolysis was observed in 27% of patients who visited our clinic.

Introduction: Entrapment neuropathy of the middle cluneal nerves (MCNs) is not commonly recognized, but it might be a cause of lower back pain.

Case Report: A 61-year old woman complained of right buttock pain that had developed gradually over 5 months. Neurological examination showed no sensory or motor disturbance in her legs, but Tinel's sign and tenderness were present in her right buttock. The patient's clinical symptom was persistently unresponsive to conservative treatment. Therefore, surgical release of the right MCN was performed under local anesthesia. Just after the operation, the patient reported that her pain around the right buttock had completely disappeared.

Conclusion: Intraoperatively, intermuscular dissection between the iliocostalis and the longissimus was useful to find the MCN squeezed by the posterior sacroiliac ligament.

The patient was 69-year-old man who had several previous spinal surgeries in other hospitals: L4-L5 lumbar disc herniation at 26 years of age; C4-C5 and C5-C6 anterior decompression and fusion at 45 years of age; L4-L5 decompression surgery at 46 years of age; and T11-L5 posterior fusion with L3-L4 posterior lumbar interbody fusion surgery at 63 years of age. He visited the first author's hospital because of recently developed walking discomfort 6 years after the last surgery. One year after the index visit, he was admitted for the progression of intermittent claudication and unstable walking. Physical examination showed slight weakness of muscle strength (level 4 on manual muscle testing) in the lower extremities and sensory disturbance below the T11 level without any abnormality of the deep tendon reflexes. Radiography showed a right-convex long thoracolumbar scoliosis with a Cobb angle of 27 degrees and loosening of pedicle screws in the T11 and T12 vertebrae. Computed tomography showed a right-sided parallel shift of loosened T11 pedicle screws and destruction of the inner wall of the spinal canal by the left screw. Severe compression of the spinal cord was observed on myelography and magnetic resonance imaging. Surgery was performed for removal of the T11 and T12 pedicle screws and proximal extension of thoracolumbar fixation up to the T7 vertebra, with special attention to avoid spinal cord injury during screw removal. After surgery, the patient recovered rapidly and was capable of walking more than 5 km cane-free without claudication or staggering one year after surgery.

Many complications at proximal instrumented vertebrae in patients undergoing long thoracolumbar spinal fusion surgery have been reported as the proximal junctional failure (PJF) or kyphosis (PJK). Though the majority of previous reports regarding PJF and PJK presented problems related to sagittal alignment, few reports have described pain and fractures related to the coronal alignment. In the present case, myelopathy with spinal canal destruction was caused by repeated lateral bending to maintain the straight standing position. This type of complication at the proximal instrumented vertebrae is relatively rare but important to avoid the development of myelopathy. Therefore, correction of the coronal alignment, as well as the sagittal alignment, at the lower lumbar and/or lumbosacral region and extended upward fixation above the T9 vertebra should be considered in the initial spinal surgery.