Atsushi Okawa

• Tokyo Medical and Dental University

There are two types of carbonated apatite (cap): A‐type and B‐type, where carbonate ions substitute for hydroxyl sites in A‐CAp and phosphate sites in B‐CAp. Despite the known capacity of CAp in supporting the activities of bone cells, the distinct potential of A‐CAp and B‐CAp as porous bone grafts is unclear. This study aimed to fabricate porous A...

Study Design Retrospective cohort study. Objective To investigate the incidence of and risk factors for segmental motor paralysis after anterior cervical spine surgery. Summary of Background Data Segmental motor paralysis is a potential complication following both anterior and posterior cervical decompression procedures; however, previous studies...

This study aimed to determine differences in the hip abductor muscle activity during clam exercise at different hip flexion and femoral anteversion angles. Thirty healthy females were divided into two groups based on the femoral anteversion angle: the excessive femoral anteversion group and the normal group. Clam exercise was performed at three dif...

Study design: Retrospective cohort study. Objectives: To compare the frequency of complications and outcomes between patients with ossification of the posterior longitudinal ligament (OPLL) of the cervical spine and those with cervical spondylotic myelopathy (CSM) who underwent anterior surgery. Summary of background data: Anterior cervical sp...

Study Design Retrospective diagnostic study Objective To automatically detect osteolytic bone metastasis lesions in the thoracolumbar region using conventional computed tomography (CT) scans, we developed a new deep learning (DL)-based computer aided detection (CAD) model. Summary of Background Data Radiographic detection of bone metastasis is of...

Purpose Although movement of the hyoid bone is different for masticatory swallowing and liquid swallowing in normal subjects, it has not been studied after cervical spine surgery. Therefore, we analyzed the swallowing dynamics of masticatory swallowing in anterior cervical spine disease surgery using foods that require chewing close to actual meals...

Background Few studies have investigated the kinematics after reverse total shoulder arthroplasty (RTSA). This study aimed to compare the shoulder kinematics in RTSA patients during shoulder abduction on the scapular plane with and without a load and yield information regarding the function of stabilizing the joints against gravity for the function...

Background Gait decline in older adults is related to falling risk, some of which contribute to injurious falls requiring medical attention or restriction of activity of daily living. Among injurious falls, distal radius fracture (DRF) is a common initial fragility fracture associated with the subsequent fracture risk in postmenopausal females. The...

Study design: A multi-institutional retrospective study. Objectives: To investigate risk factors of mechanical failure in three-column osteotomy (3COs) in patients with adult spinal deformity (ASD), focusing on the osteotomy level. Methods: We retrospectively reviewed 111 patients with ASD who underwent 3COs with at least 2 years of follow-up....

Introduction Intraoperative periprosthetic fracture, one of the most frequent complications of total hip arthroplasty, is a very important factor that affects rehabilitation, hospitalization time, and cost of treatment. Osteoporosis is common in total hip arthroplasty patients and likely contributes to the increasing incidence of periprosthetic fra...

Ossification of the posterior longitudinal ligament of the spine (OPLL) is an intractable disease leading to severe neurological deficits. Its etiology and pathogenesis are primarily unknown. The relationship between OPLL and comorbidities, especially type 2 diabetes (T2D) and high body mass index (BMI), has been the focus of attention; however, no...

Ossification of the posterior longitudinal ligament of the spine (OPLL) is an intractable disease leading to severe neurological deficits. Its etiology and pathogenesis are primarily unknown. The relationship between OPLL and comorbidities, especially type 2 diabetes (T2D) and high body mass index (BMI), has been the focus of attention; however, no...

Ossification of the posterior longitudinal ligament of the spine (OPLL) is an intractable disease leading to severe neurological deficits. Its etiology and pathogenesis are primarily unknown. The relationship between OPLL and comorbidities, especially type 2 diabetes (T2D) and high body mass index (BMI), has been the focus of attention; however, no...

Ossification of the posterior longitudinal ligament of the spine (OPLL) is an intractable disease leading to severe neurological deficits. Its etiology and pathogenesis are primarily unknown. The relationship between OPLL and comorbidities, especially type 2 diabetes (T2D) and high body mass index (BMI), has been the focus of attention; however, no...

Osteocytes have recently been identified as a new regulator of bone remodeling, but the detailed mechanism of their differentiation from osteoblasts remains unclear. The purpose of this study is to identify cell cycle regulators involved in the differentiation of osteoblasts into osteocytes and determine their physiological significance. The study...

Study design: A prospective multicenter study. Objective: To investigate the effect of preoperative symptom duration on neurological recovery for the treatment of cervical ossification of the posterior longitudinal ligament (OPLL). Summary of background data: The optimal timing to perform surgery in the setting of cervical OPLL remains unknown...

Early detection of cervical myelopathy (CM) is important for a favorable outcome, as its prognosis is poor when left untreated. We developed a screening method for CM using machine learning-based analysis of the drawing behavior of 38 patients with CM and 66 healthy volunteers. Using a stylus pen, the participants traced three different shapes disp...

Objectives : We aimed to review the most recent articles on the rehabilitation of patients after coronavirus disease 2019 (COVID-19) and to identify the methods and effects of rehabilitation on such patients. Methods : A literature search was conducted using PubMed and Web of Science from study inception to October 2022 using the following search t...

Objective Early detection and intervention are essential for the mitigation of degenerative cervical myelopathy (DCM). However, although several screening methods exist, they are difficult to understand for community-dwelling people, and the equipment required to set up the test environment is expensive. This study investigated the viability of a D...

p>An adjustable helmet-style magnetoresistive (MR) sensor array, a room-temperature magnetic flux sensor, was developed to demonstrate simultaneous multipoint measurement of the somatosensory evoked magnetic field (SEF). The SEF was measured in three healthy subjects using an array of 30-channel MR sensors placed on the left hemisphere of the head...

p>An adjustable helmet-style magnetoresistive (MR) sensor array, a room-temperature magnetic flux sensor, was developed to demonstrate simultaneous multipoint measurement of the somatosensory evoked magnetic field (SEF). The SEF was measured in three healthy subjects using an array of 30-channel MR sensors placed on the left hemisphere of the head...

p>An adjustable helmet-style magnetoresistive (MR) sensor array, a room-temperature magnetic flux sensor, was developed to demonstrate simultaneous multipoint measurement of the somatosensory evoked magnetic field (SEF). The SEF was measured in three healthy subjects using an array of 30-channel MR sensors placed on the left hemisphere of the head...

Study design: Retrospective comparative study. Objective: This study aimed to investigate factors associated with postoperative unfavorable ambulatory status following surgery for metastatic spinal tumors using a nationwide in-hospital database. Summary of background data: Surgical treatment for metastatic spinal tumors can improve ambulatory...

Osteosarcoma is a malignant tumor that histologically forms a tumor-like osteoid or bone. Plasminogen activator inhibitor 1 (PAI-1) is highly expressed in the blood of patients with various malignant tumors or in the tumors themselves, and its expression is positively correlated with tumor grade. Therefore, PAI-1 is a potential target for cancer th...

Study design: A prospective multicenter study. Objective: To investigate the incidence of loss of cervical lordosis after laminoplasty for cervical ossification of the posterior longitudinal ligament (OPLL). We also sought to determine associated risk factors and the relationship with patient-reported outcomes. Summary of background data: Loss...

Peripheral nerve injury (PNI) induces severe functional loss in extremities. Progressive denervation and atrophy occur in the muscles if the nerve repair is delayed for long periods of the time. To overcome these difficulties, detailed mechanisms should be determined for neuromuscular junction (NMJ) degeneration in target muscles after PNI and rege...

Patients on bone-modifying agents (BMAs) for bone metastases are at risk of atypical femoral fractures (AFFs), which can lead to a sudden deterioration in performance status. In this study, we sought to determine the prevalence of radiographic precursory signs of AFF in patients on oncologic BMAs. Forty-two patients (23 men, 19 women; mean age 68.8...

Anterior decompression and fusion (ADF) using the floating method for cervical ossification of the posterior longitudinal ligament (OPLL) is an ideal surgical technique, but it has a specific risk of insufficient decompression caused by the impingement of residual ossification. Augmented reality (AR) support is a novel technology that enables the s...

Bone is one of the largest organ systems in humans and is considered to regulate whole-body homeostasis in cooperation with other organs. We have previously reported that a sympathetic or sensory nervous system inside bone regulates bone homeostasis. However, the detailed regulatory mechanism, including the distribution of nerves inside bone, remai...

We prospectively investigated the postoperative dysphagia in cervical posterior longitudinal ligament ossification (C-OPLL) and cervical spondylotic myelopathy (CSM) to identify the risk factors of each disease and the incidence. A series of 55 cases with C-OPLL: 13 anterior decompression with fusion (ADF), 16 posterior decompression with fusion (P...

Study design: A prospective multi-institutional observational study. Objective: To investigate and identify risk factors for residual neuropathic pain after surgery in patients with cervical ossification of posterior longitudinal ligament (c-OPLL). Summary of background data: Patients with c-OPLL often require surgery for numbness and paralysi...

Background: It may be difficult to define what would constitute an abnormal spinal sagittal alignment. The same degree of malalignment may be found both in patients with pain and disability and in asymptomatic individuals. This study focuses on elderly farmers who characteristically have a kyphotic spine, in addition to local residents. It questio...

Background: The differential diagnosis of neuropathic pain, especially discrimination between neuropathic pain caused by spinal canal stenosis (SCS) and neuropathic pain associated with causes other than SCS, is sometimes difficult; however, it is important for surgical application. Methods: We established a reliable method for measuring lysopho...

Purpose Postoperative complication prediction helps surgeons to inform and manage patient expectations. Deep learning, a model that finds patterns in large samples of data, outperform traditional statistical methods in making predictions. This study aimed to create a deep learning-based model (DLM) to predict postoperative complications in patients...

To evaluate the radiological differences between diffuse idiopathic skeletal hyperostosis (DISH) and ankylosing spondylitis (AS) using whole spine computed tomography (CT), including the spine and sacroiliac joint (SIJ). The ossification and bridging of spinal ligament and fusion of the facet joint and SIJ were evaluated in 111 patients who were di...

Background context: Lumbar spinal canal stenosis caused by degenerative lumbar spondylolisthesis is one of the most common indications for spinal surgery. However, the factors that influence its long-term (>10 years) outcomes remain unknown. Design: This is a post-hoc analysis of a prospective randomized study. Purpose: This study aimed to det...

Early detection of cervical myelopathy (CM) is important for a favorable outcome, as its prognosis is poor if left untreated. We developed a screening method for CM using machine learning to analyze a drawing behavior. A total of 38 patients with CM and 66 healthy volunteers were enrolled. Using a stylus pen, they traced three different shapes disp...

Pneumothorax is a rare surgical complication in spinal surgery with thoracic pedicle screws. The penetrating endplate screw (PES) technique has been developed as a strong alternative spinal anchor to conventional pedicle screws for diffuse idiopathic skeletal hyperostosis (DISH). We present an intraoperative pneumothorax without deviation to the th...

Objective: To compare forward head posture (FHP) in natural and corrected head postures between patients with nonspecific neck pain (NSNP) and controls, and to clarify the relationship between natural- and corrected-head posture angle differences and deep cervical flexor function. Design: Survey study Setting: Patients with NSNP were outpatients at...

This prospective multicenter study, established by the Japanese Ministry of Health, Labour and Welfare and involving 27 institutions, aimed to compare postoperative outcomes between laminoplasty (LM) and posterior fusion (PF) for cervical ossification of the posterior longitudinal ligament (OPLL), in order to address the controversy surrounding the...

To determine the pathogenesis of trapeziometacarpal (TMC) joint instability, which leads to osteoarthritis, we investigated the anatomical relationships among the surrounding ligaments, muscles (first dorsal interosseous [FDI] and opponens pollicis [OPP]), and joint capsule. We examined the bone morphology and cortical bone thickening in 25 cadaver...

Aims Osteoporosis is common in total hip arthroplasty (THA) patients. It plays a substantial factor in the surgery’s outcome, and previous studies have revealed that pharmacological treatment for osteoporosis influences implant survival rate. The purpose of this study was to examine the prevalence of and treatment rates for osteoporosis prior to TH...

Bone Joint Res 2022;11(12):873-880. HIP The prevalence and treatment of osteoporosis in patients undergoing total hip arthroplasty and the levels of biochemical markers of bone turnover Aims Osteoporosis is common in total hip arthroplasty (THA) patients. It plays a substantial factor in the surgery's outcome, and previous studies have revealed tha...

Background context: Dysphagia is one of the postoperative complications of cervical degenerative disorders. However, few studies have evaluated the pre- and postoperative swallowing function in detail. Purpose: To analyze pre- and postoperative swallowing dynamics kinetically and investigate factors associated with postoperative dysphagia in pat...

The ideal surgical strategy for cervical ossification of the posterior longitudinal ligament (OPLL) remains controversial due to the lack of high-quality evidence. Herein, we prospectively investigated the surgical outcomes of anterior cervical decompression with fusion (ADF) and laminoplasty (LAMP) with cervical OPLL. Three hundred patients were i...

BACKGROUND CONTEXT Although osteoporotic vertebral fractures (OVFs) are the most common type of osteoporotic fracture, few reports have closely investigated the factors contributing to the quality of life (QOL) in the chronic phase after thoracolumbar OVFs using detailed radiographic evaluation. PURPOSE This study aimed to identify factors associa...

Objective: To evaluate the radiological differences between diffuse idiopathic skeletal hyperostosis (DISH) and ankylosing spondylitis (AS) using whole spine computed tomography (CT), including the spine and sacroiliac joint (SIJ) Methods: The ossification and bridging of spinal ligament and fusion of the facet joint and SIJ were evaluated in 111 p...

Background: Residual acetabular dysplasia in children after reduction of hip dislocation is often treated using Salter innominate osteotomy to prevent future osteoarthritis. Preventive surgery for asymptomatic patients, which could result in overtreatment, should be carefully applied with consideration of patients' opinions. In this study, we aime...

Study design: Prospective comparative study. Objective: To investigate the benefits of postoperative application of lumbosacral orthosis after single-level discectomy for lumbar disc herniation (LDH). Summary of background data: Although many surgeons use postoperative lumbosacral orthosis for patients with LDH, there is no clear evidence to s...

Background Surgeons should be aware of vascular injury during THA due to the proximity of major vessels. However, there is no report with the anterolateral approach in the supine position. Case presentation We report a case of a 70 year-old man referred to our hospital as a diagnosis of osteoarthritis of the left hip. The patient underwent THA via...

The mechanistic regulation of bone mass in aged animals is poorly understood. In this study, we examined the role of SIRT6, a longevity-associated factor, in osteocytes, using mice lacking Sirt6 in Dmp-1 -expressing cells (cKO mice) and the MLO-Y4 osteocyte-like cell line. cKO mice exhibited increased osteocytic expression of Sost, Fgf23 and senesc...

BACKGROUND As cervical myelopathy (CM) is a progressive disease, early detection and intervention are essential for its mitigation. While several screening methods exist, they are difficult to understand for community-dwelling people, and the equipment required to set up the test environments is expensive. Thus, a simple screening system is necessa...

Background The association of the reactive strength index (RSI) during single-limb vertical continuous jumps (SVCJs) with single-limb hop tests in athletes after anterior cruciate ligament reconstruction (ACLR) is unclear. Thus, this study aimed to confirm the measurement properties of the RSI during SVCJs in athletes with ACLR at the phase of dete...

Background Nerve palsy following total hip arthroplasty (THA) critically impacts patient clinical function. However, few studies have focused on femoral nerve palsy (FNP) following THA via the modified Watson-Jones approach. Previous reports have suggested that THA, regardless of the approach, is associated with several FNP risk factors, including...

BACKGROUND Cervical myelopathy (CM) causes several symptoms such as clumsiness of the hands, and often requires surgery. Screening and early diagnosis of CM are important because some patients are unaware of their early symptoms and consult a surgeon only after their condition has become severe. The 10-second hand grip and release (10-s) test is co...

Background Cervical myelopathy (CM) causes several symptoms such as clumsiness of the hands and often requires surgery. Screening and early diagnosis of CM are important because some patients are unaware of their early symptoms and consult a surgeon only after their condition has become severe. The 10-second hand grip and release test is commonly u...

Study design: A prospective multicenter study. Objective: This study aims to evaluate patient-reported outcomes using the Japanese Orthopedic Association Cervical Myelopathy Evaluation Questionnaire (JOACMEQ) and clarify clinical factors that affect the therapeutic effects for patients with cervical ossification of the posterior longitudinal lig...

Superficial siderosis (SS) of the central nervous system is a rare disease caused by chronic and repeated hemorrhages in the subarachnoid space. Recently, attention has been paid on the association of SS and dural defect with ventral fluid-filled collection in the spinal canal (VFCC). The pathophysiology of hemosiderin deposition in patients with S...

Background: The purpose of this study was to clarify the clinical features of ossification of the posterior longitudinal ligament (OPLL) and extreme ossification at multiple sites. Methods: This prospective study involved patients with a diagnosis of cervical OPLL at 16 institutions in Japan. Patient-reported outcome measures, including response...

Background: Ossification of the posterior longitudinal ligament of the spine (OPLL) is an intractable disease, leading to severe neurological deficits. Its etiology and pathogenesis are mostly unknown. The relationship between OPLL and comorbidities, especially type 2 diabetes (T2D) and body mass index (BMI), has been the focus of attention; howeve...

For ossification of the posterior longitudinal ligament (OPLL) and cervical spondylotic myelopathy (CSM), anterior decompression with fusion (ADF) can accurately achieve spinal decompression. However, the difference in perioperative complications in ADF between OPLL and CSM is poorly described. This study aimed to investigate the perioperative comp...

Excluding clinical trials, there is limited evidence on the effect of 12 months of romosozumab treatment on bone mineral density (BMD) increase in real‐world clinical practice because its use has only been approved recently. Thus, this study aimed to investigate the real‐world effect of 12 months of romosozumab treatment on BMD increase and identif...

Differentiation of mesenchymal stem cells (MSCs) into osteoblasts is a critical process for proper skeletal development and acquisition/maintenance of bone mass. However, since this regulatory mechanism has not yet been fully elucidated, the treatment of severe osteoporosis and fractures is a challenge. Here, through a comprehensive analysis of gen...

Background: Nerve palsy following total hip arthroplasty (THA) critically impacts patient clinical function. However, few studies have focused on femoral nerve palsy (FNP) following THA via the modified Watson-Jones approach. Previous reports have suggested that THA, regardless of the approach, is associated with several FNP risk factors, including...

Positive association between ossification of the posterior longitudinal ligament of the spine (OPLL) and obesity is widely recognized; however, few studies focused on the effects of obesity on treatment of cervical OPLL. The effects of obesity on surgical treatment of cervical OPLL were investigated by a Japanese nationwide, prospective study. Over...

The cranial vertical angle (CVA) and cranial rotation angle (CRA) are used in clinical settings because they can be measured on lateral photographs of the head and neck. We aimed to clarify the relationship between CVA and CRA photographic measurements and radiographic cervical spine alignment. Twenty-six healthy volunteers were recruited for this...

Introduction: In Japan, cervical total disc replacement (TDR) was approved in 2017. However, because of its short history, no comparative study between cervical TDR and anterior cervical discectomy with fusion (ACDF) has been conducted in the country. Therefore, we examined and compared the surgical outcomes of TDR and ACDF for one-level cervical d...

Background Treatment for pyogenic spondylitis tends to be prolonged in controlling the infection; however, few reports have examined the factors associated with the duration required to control infection. We analyzed a consecutive cohort of patients who underwent surgery for pyogenic spondylitis to identify predictors associated with the duration r...

Neuropathic pain, a heterogeneous condition, affects 7-10% of the general population. To date, efficacious and safe therapeutic approaches remain limited. Antisense oligonucleotide (ASO) therapy has opened the door to treat spinal muscular atrophy, with many ongoing clinical studies determining its therapeutic utility. ASO therapy for neuropathic p...

Background : Parkes-Weber syndrome is a rare congenital vascular abnormality involving aggressive overgrowth of vascular structures. Destruction of the surrounding bone, muscle, and joint tissues often occurs, resulting in pain while walking and reduced range of motion. Current treatments for this arteriovenous malformation options include conserva...

Background Spinal schwannoma recurs after initial surgery at a rate of 4%–6%, with known risk factors including subtotal resection, multilevel involvement, large tumor size, and malignant histopathology. This study examined risk factors for schwannoma recurrence and residual tumor regrowth. Methods Sixty-five patients who underwent resection of sp...

Objective To measure the neuromagnetic fields of carpal tunnel syndrome patients after electrical digital nerve stimulation and evaluate median nerve function with high spatial resolution. Methods A superconducting quantum interference device magnetometer system was used to record neuromagnetic fields at the carpal tunnel after electrical stimulat...

Purpose Although the understanding of the mechanisms of low back pain due to spinopelvic sagittal imbalance has strengthened, the understanding of the mechanisms of neck pain remains insufficient. Thus, this study aimed to identify the factors associated with preoperative and postoperative neck pain in patients with degenerative cervical myelopathy...

Objectives: This study aimed to describe the rehabilitation characteristics of patients with acute stage coronavirus disease managed with extracorporeal membrane oxygenation (ECMO) in the intensive care unit. Methods: This retrospective study enrolled coronavirus disease patients who underwent rehabilitation following ECMO between April 21, 2020...

Electrophysiological examination is important for the diagnosis and evaluation of nerve function in carpal tunnel syndrome (CTS). Electrophysiological severity classifications of CTS using a nerve conduction study (NCS) have been reported, and there are many reports on the relationship between severity classifications and clinical symptoms. The exi...

Although osteoporotic vertebral fractures (OVFs) are the most common type of osteoporotic fracture, few reports have investigated the factors contributing to residual low back pain in the chronic phase after OVFs by using radiographic evaluation. We examined the contribution of nonunion, vertebral deformity, and thoracolumbar alignment to the sever...

Objective To visualize the neural activity of the ulnar nerve at the elbow using magnetoneurography (MNG). Methods Subjects were asymptomatic volunteers (eight men and one woman; age, 26–53 years) and a male patient with cubital tunnel syndrome (age, 54 years). The ulnar nerve was electrically stimulated at the left wrist and evoked magnetic field...

Background There are few reports concerning determinants of the surgical outcome of anterior decompression and fusion (ADF) when performed for ossification of the posterior longitudinal ligament of the thoracic spine (T-OPLL). We investigated prognostic factors associated with neurological recovery in the patients with T-OPLL. Methods This retrosp...

Objective: It is unclear whether anterior cervical decompression and fusion (ADF) or laminoplasty (LMP) results in better outcomes for patients with K-line-positive (+) cervical ossification of the posterior longitudinal ligament (OPLL). The purpose of the study is to compare surgical outcomes and complications of ADF versus LMP in patients with K...

Aim The orthopedic surgery unit in our suburb serves a large elderly trauma population in addition to providing elective surgeries. As patients with hip fractures have become older and at higher risk of medical complications, our hospital has initiated integrated co-management of these patients by orthopedic surgeons and geriatricians from the poin...

Background Context Its rare prevalence and subtle radiological changes often lead to difficulties in diagnosing cervical ossification of the posterior longitudinal ligament (OPLL) on plain radiographs. However, OPLL progression may lead to trauma-induced spinal cord injury, resulting in severe paralysis. To address the difficulties in diagnosis, a...