MDPI Acta Medica Okayama 1010-660X 58 5 2022 Mechanical Study of Various Pedicle Screw Systems including Percutaneous Pedicle Screw in Trauma Treatment 565 EN Yoshiaki Oda Department of Orthopaedic Surgery, Okayama University Hospital Tomoyuki Takigawa Department of Orthopaedic Surgery, Kobe Red Cross Hospital Yasuo Ito Department of Orthopaedic Surgery, Kobe Red Cross Hospital Haruo Misawa Department of Orthopaedic Surgery, Okayama University Hospital Tomoko Tetsunaga Department of Orthopaedic Surgery, Okayama University Hospital Koji Uotani Department of Orthopaedic Surgery, Okayama University Hospital Toshifumi Ozaki Department of Orthopaedic Surgery, Dentistry, and Pharmaceutical Sciences, Graduate School of Medicine, Okayama University Background and Objectives: Spine surgery using a percutaneous pedicle screw placement (PPSP) is widely implemented for spinal trauma. However, percutaneous systems have been reported to have weak screw-rod connections. In this study, conventional open and percutaneous systems were biomechanically evaluated and compared. Material and Methods: The experiments were performed in two stages: the first stage was a break test, whereas the second stage was a fatigue test. Four systems were used for the experiments. System 1 was intended for conventional open surgery (titanium rod with a 6.0 mm diameter, using a clamp connecting mechanism). System 2 was a percutaneous pedicle screw (PPS) system for trauma (titanium alloy rod with a 6.0 mm diameter, using ball ring connections). System 3 was a PPS system for trauma (cobalt-chromium alloy rod with a 6.0 mm diameter, using sagittal adjusting screw connections). System 4 was a general-purpose PPS system (titanium alloy rod with a 5.5 mm diameter, using a mechanism where the adapter in the head holds down the screw). Results: Stiffness values of 54.8 N/mm, 43.1 N/mm, 90.9 N/mm, and 39.3 N/mm were reported for systems 1, 2, 3, and 4, respectively. The average number of load cycles in the fatigue test was 134,393, 40,980, 1,550,389, and 147,724 for systems 1 to 4, respectively. At the end of the test, the displacements were 0.2 mm, 16.9 mm, 1.2 mm, and 8.6 mm, respectively. System 1, with a locking mechanism, showed the least displacement at the end of the test. Conclusion: A few PPS systems showed better results in terms on stiffness and life than the open system. The experiments showed that mechanical strength varies depending on the spinal implant. The experiments conducted are essential and significant to provide the mechanical strength required for surgical reconstruction. No potential conflict of interest relevant to this article was reported.

MDPI Acta Medica Okayama 1010-660X 58 5 2022 Long-Term Results of Posterior Vertebral Column Resection for Severe Thoracolumbar Kyphosis with Achondroplastic Patients: A Case Series 605 EN Masato Tanaka Department of Orthopaedic Surgery, Okayama University Hospital Tsang-Tung Chan Department of Orthopaedic Surgery, Okayama University Hospital Haruo Misawa Department of Orthopaedic Surgery, Okayama University Hospital Koji Uotani Department of Orthopaedic Surgery, Okayama University Hospital Shinaya Arataki Department of Orthopaedic Surgery, Okayama University Hospital Tomoyuki Takigawa Department of Orthopaedic Surgery, Okayama University Hospital Tetsuro Mazaki Department of Orthopaedic Surgery, Okayama University Hospital Yoshihisa Sugimoto Department of Orthopaedic Surgery, Okayama University Hospital Background and Objectives: Thoracolumbar kyphosis is one of the most frequent skeletal manifestations in patients with achondroplasia. Few papers have been published on the surgical treatment of this condition, especially in skeletally mature patients. With this study, we presented a retrospective case series of long-term surgical results for achondroplastic patients with severe thoracolumbar kyphosis. This study was conducted to evaluate the outcome of surgical treatment for thoracolumbar kyphosis in patients associated with achondroplasia presenting with paraparesis. Materials and Methods: Three patients with achondroplasia who developed neurologic deficits due to severe thoracolumbar kyphosis and underwent surgical treatment were evaluated (mean age 22.3 years; mean follow-up 9.3 years). All patients were treated with posterior vertebral column resection (p-VCR) of hypoplastic apical vertebrae with a cage and segmental instrumentation. Neurologic outcomes (JOA scores), correction of kyphosis, and operative complications were assessed. Results: All patients had back pain, neurological deficits, and urinary disturbance before surgery. The average preoperative JOA score was 8.3/11 points, which was improved to 10.7/11 points at the final follow-up (mean recovery rate 83%). All patients obtained neurologic improvement after surgery. The mean preoperative kyphotic angle was 117 degrees (range 103 degrees-126 degrees). The postoperative angles averaged 37 degrees (range 14 degrees-57 degrees), resulting in a mean correction rate of 67%. All patients had postoperative complications such as rod breakage and/or surgical site infection. Conclusions: The long-term results of p-VCR were acceptable for treating thoracolumbar kyphosis in patients with achondroplasia. To perform this p-VCR safely, spinal navigation and neuromonitoring are inevitable when resecting non anatomical fused vertebrae and ensuring correct pedicle screw insertion. However, surgical complications such as rod breakage and surgical site infection may occur at a high rate, making informed consent very important when surgery is indicated. No potential conflict of interest relevant to this article was reported.

Nature Research Acta Medica Okayama 2045-2322 11 1 2021 Quantification of patellar tendon reflex using portable mechanomyography and electromyography devices 2284 EN Hironori Tsuji Department of Orthopaedic Surgery, Dentistry, and Pharmaceutical Sciences, Okayama University Graduate School of Medicine Haruo Misawa Department of Orthopaedic Surgery, Okayama University Hospital Tomoyuki Takigawa Department of Orthopaedic Surgery, Kobe Red Cross Hospital Tomoko Tetsunaga Department of Orthopaedic Surgery, Okayama University Hospital Kentaro Yamane Department of Orthopaedic Surgery, Okayama University Hospital Yoshiaki Oda Department of Orthopaedic Surgery, Okayama University Hospital Toshifumi Ozaki Department of Orthopaedic Surgery, Dentistry, and Pharmaceutical Sciences, Okayama University Graduate School of Medicine Deep tendon reflexes are one of the main components of the clinical nervous system examinations. These assessments are inexpensive and quick. However, evaluation can be subjective and qualitative. This study aimed to objectively evaluate hyperreflexia of the patellar tendon reflex using portable mechanomyography (MMG) and electromyography (EMG) devices. This study included 10 preoperative patients (20 legs) who had a pathology that could cause bilateral patellar tendon hyperreflexia and 12 healthy volunteers (24 legs) with no prior history of neurological disorders. We attached MMG/EMG sensors onto the quadriceps and tapped the patellar tendon with maximal and constant force. Our results showed a significantly high amplitude of the root mean square (RMS) and low frequency of the mean power frequency (MPF) in the rectus femoris, vastus medialis, and vastus lateralis muscles in both EMG and MMG with both maximal and constant force. Especially in the patients with cervical and thoracic myelopathy, the receiver operating characteristic (ROC) curve for diagnosing hyperreflexia of the patellar tendon showed a moderate to very high area under the curve for all EMG-RMS, EMG-MPF, MMG-RMS, and MMG-MPF values. The use of EMG and MMG for objectively quantifying the patellar tendon reflex is simple and desirable for future clinical applications and could help diagnose neurological disorders. No potential conflict of interest relevant to this article was reported.

Springer Acta Medica Okayama 1749-799X 15 1 2020 Short-term outcomes of mirogabalin in patients with peripheral neuropathic pain: a retrospective study 191 EN Tomoko Tetsunaga Department of Orthopedic Surgery, Okayama University Hospital Tomonori Tetsunaga Department of Orthopedic Surgery, Okayama University Hospital Keiichiro Nishida Department of Orthopedic Surgery, Okayama University Hospital Haruo Misawa Department of Orthopedic Surgery, Okayama University Hospital Tomoyuki Takigawa Department of Orthopedic Surgery, Okayama University Hospital Kentaro Yamane Department of Orthopedic Surgery, Okayama University Hospital Hironori Tsuji Department of Orthopedic Surgery, Okayama University Hospital Yoshitaka Takei Department of Orthopedic Surgery, Kurashiki Municipal Hospital Toshifumi Ozaki Department of Orthopedic Surgery, Okayama University Hospital Background</br> Mirogabalin, which is approved for the treatment of peripheral neuropathic pain in Japan, is a ligand for the α2δ subunit of voltage-gated calcium channels. Both pregabalin and mirogabalin act as nonselective ligands at the α2δ-1 and α2δ-2 subunits. Mirogabalin has a unique binding profile and long duration of action. Pregabalin has been reported to produce intolerable adverse effects in some patients. This study investigated outcomes associated with mirogabalin administration in patients with peripheral neuropathic pain who ceased treatment with pregabalin.</br> Methods</br> We retrospectively assessed peripheral neuropathic pain using the neuropathic pain screening questionnaire (NeP score) in 187 patients (58 men, 129 women) who were treated with mirogabalin. All patients had switched from pregabalin to mirogabalin due to lack of efficacy or adverse events. Differences in the treatment course (i.e., numeric rating scale (NRS) scores) were compared using one-way analysis of variance with Bonferroni post hoc tests.</br> Results</br> The mean age of the patients was 72.3 years (range, 30–94 years), and the mean duration of disease was 37 months (range, 3–252 months). After treatment with mirogabalin for 1 week, NRS scores significantly decreased compared with baseline and continued to decrease over time. After 8 weeks, NRS scores improved by ≥ 30% from baseline in 113 patients (69.3%). Twenty-four patients (12.8%) stopped mirogabalin treatment due to adverse events. Somnolence (26.7%), dizziness (12.3%), edema (5.9%), and weight gain (0.5%) were noted as adverse events of mirogabalin.</br> Conclusions</br> The results of this investigation indicate that mirogabalin is safe and effective for reducing peripheral neuropathic pain. No potential conflict of interest relevant to this article was reported.

MDPI Acta Medica Okayama 1422-0067 20 23 2019 Multipotent Neurotrophic Effects of Hepatocyte Growth Factor in Spinal Cord Injury 6078 EN Kentaro Yamane Department of Intelligent Orthopaedic System Development, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Haruo Misawa Department of Orthopaedic Surgery, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Tomoyuki Takigawa Department of Orthopaedic Surgery, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Yoshihiro Ito Nano Medical Engineering Laboratory, RIKEN Toshifumi Ozaki Department of Orthopaedic Surgery, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Akihiro Matsukawa Department of Pathology and Experimental Medicine, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Spinal cord injury (SCI) results in neural tissue loss and so far untreatable functional impairment. In addition, at the initial injury site, inflammation induces secondary damage, and glial scar formation occurs to limit inflammation-mediated tissue damage. Consequently, it obstructs neural regeneration. Many studies have been conducted in the field of SCI; however, no satisfactory treatment has been established to date. Hepatocyte growth factor (HGF) is one of the neurotrophic growth factors and has been listed as a candidate medicine for SCI treatment. The highlighted effects of HGF on neural regeneration are associated with its anti-inflammatory and anti-fibrotic activities. Moreover, HGF exerts positive effects on transplanted stem cell differentiation into neurons. This paper reviews the mechanisms underlying the therapeutic effects of HGF in SCI recovery, and introduces recent advances in the clinical applications of HGF therapy. No potential conflict of interest relevant to this article was reported.

Okayama University Medical School Acta Medica Okayama 0386-300X 74 1 2020 Minimally Invasive Surgery for Unstable Pelvic Ring Fractures: Transiliac Rod and Screw Fixation 27 32 EN Kazukiyo Toda Department of Orthopaedic Surgery, Kobe Red Cross Hospital Yukihisa Yagata Department of Orthopaedic Surgery, Hyogo Emergency Medical Center, Takeshi Kikuchi Department of Orthopaedic Surgery, Kobe Red Cross Hospital Tomoyuki Takigawa Department of Orthopaedic Surgery, Okayama University Hospital Yasuo Ito Department of Orthopaedic Surgery, Kobe Red Cross Hospital Original Article 10.18926/AMO/57949 Pelvic fractures occur with high-energy trauma, and the patient’s clinical status is unstable. Although a number of surgical methods for unstable pelvic fractures are available, none can achieve strong fixation with minimal invasiveness. We describe a surgical transiliac rod and screw fixation (TIF) procedure that provides minimally invasive fixation using a spinal implant for unstable pelvic ring fractures, and we retrospectively analyzed the procedure’s outcomes in 27 patients with type B or C1 fractures (based on the AO/ATO classification system). Small skin incisions are made above the posterior superior iliac spines on both sides. The ilium is partially resected, and two iliac screws are inserted on each side. The spinous process of the sacral spine is then shaved, and the iliac screws are connected to 2 rods, one placed caudal to the other. Corrective manipulation is performed at the fracture site, and the rods are connected with connectors. Favorable fracture reduction, defined as a rating of ‘excellent’ or ‘good,’ was achieved in 77.8% of the patients. Transiliac rod and screw fixation (TIF) will be a useful therapeutic option for unstable pelvic ring fractures. No potential conflict of interest relevant to this article was reported.

Okayama University Medical School Acta Medica Okayama 0386-300X 71 4 2017 Cervical Spine Osteoradionecrosis 345 349 EN Masato Tanaka Department of Orthopaedic Surgery, Okayama University Hospital Yoshihisa Sugimoto Department of Orthopaedic Surgery, Okayama University Hospital Tomoyuki Takigawa Department of Orthopaedic Surgery, Okayama University Hospital Yoshihiro Kimata Department of Plastic and Reconstructive Surgery, Okayama University Hospital Toshifumi Ozaki Department of Orthopaedic Surgery, Okayama University Hospital Case Report 10.18926/AMO/55312 Osteoradionecrosis (ORN), a well-known complication of radiotherapy in the mandibular bone, is very rare in the cervical spine. The authors report the result of a 3-year follow-up of a 63-year-old female patient with ORN of the cervical spine. The patient had a history of laryngeal carcinoma and was treated with chemotherapy and radiation therapy with a total of 120 Gy. Eight years later, she developed acute, severe neck pain due to cervical spine necrosis. The authors performed vascularized fibular bone graft and posterior pedicle screw fixation to reconstruct her cervical spine. The patient was successfully treated with surgery, and cervical alignment was preserved. She had neither neurological deficits nor severe neck pain at her final follow-up 3 years later. Delaying treatment of ORN may be life threatening, so the early diagnosis of this condition is important for patients who receive radiotherapy. Otolaryngologists and spine surgeons should understand this potential complication to speed diagnosis and treatment as early as possible. No potential conflict of interest relevant to this article was reported.

Okayama University Medical School Acta Medica Okayama 0386-300X 71 2 2017 Scoliosis in Patients with Severe Cerebral Palsy: Three Different Courses in Adolescents 119 126 EN Yoshiaki Oda Department of Orthopaedic Surgery, Okayama University Hospital Tomoyuki Takigawa Department of Orthopaedic Surgery, Okayama University Hospital Yoshihisa Sugimoto Department of Orthopaedic Surgery, Okayama University Hospital Masato Tanaka Department of Orthopaedic Surgery, Okayama University Hospital Hirofumi Akazawa Asahikawasou Ryouiku Iryou Center Toshifumi Ozaki Department of Orthopaedic Surgery, Okayama University Hospital Original Article 10.18926/AMO/54980 Patients with cerebral palsy (CP) frequently present with scoliosis; however, the pattern of curve progression is difficult to predict. We aimed to clarify the natural course of the progression of scoliosis and to identify scoliosis predictors. This was a retrospective, single-center, observational study. Total of 92 CP patients from Asahikawasou Ryouiku Iryou Center in Okayama, Japan were retrospectively analyzed. Cobb angle, presence of hip dislocation and pelvic obliquity, and Gross Motor Function Classification System (GMFCS) were investigated. Severe CP was defined as GMFCS level IV or V. The mean observation period was 10.7 years. Thirtyfour severe CP patients presented with scoliosis and were divided into 3 groups based on their clinical courses: severe, moderate and mild. The mean Cobb angles at the final follow-up were 129°, 53°, and 13° in the severe, moderate, and mild groups, respectively. The average progressions from 18 to 25 years were 2.7°/year, 0.7°/year, and 0.1°/year in the severe, moderate, and mild curve groups, respectively. We observed the natural course of scoliosis and identified 3 courses based on the Cobb angle at 15 and 18 years of age. This method of classification may help clinicians predict the patients’ disease progression. No potential conflict of interest relevant to this article was reported.

Okayama University Medical School Acta Medica Okayama 0386-300X 70 6 2016 Neurological Recovery after Posterior Spinal Surgery in Patients with Metastatic Epidural Spinal Cord Compression 449 453 EN Noriyuki Watanabe Department of Orthopaedic Surgery, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Yoshihisa Sugimoto Department of Orthopaedic Surgery, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Masato Tanaka Department of Orthopaedic Surgery, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Tetsuro Mazaki Department of Orthopaedic Surgery, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Shinya Arataki Department of Orthopaedic Surgery, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Tomoyuki Takigawa Department of Orthopaedic Surgery, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Masaki Kataoka Department of Orthopaedic Surgery, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Toshiyuki Kunisada Department of Medical Materials for Musculoskeletal Reconstruction, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Toshifumi Ozaki Department of Orthopaedic Surgery, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Original Article 10.18926/AMO/54807 Metastatic epidural spinal cord compression (MESCC) is a common complication in patients with a malignant tumor, but it is difficult to decide the proper time to perform the necessary surgery. Here we analyzed the prognostic factors for postoperative walking ability. We retrospectively reviewed the cases of 112 MESCC patients treated surgically at our institute and divided them into ambulatory (n＝ 88) and non-ambulatory (n＝24) groups based on their American Spinal Injury Association (ASIA) Impairment Scale grades at the final follow-up. We also classified the patients preoperatively using the revised Tokuhashi score. We assessed the correlation between preoperative or intraoperative factors and postoperative walking ability in both groups. Of the 10 patients classified preoperatively as grade A or B, 2 (20 ) were ambulatory at the final follow-up. Of the 102 patients classified preoperatively as grade C, D or E, 86 (84 ) were ambulatory at the final follow-up (p＜0.001). There were no significant differences between the groups in the average total Tokuhashi score. Our analysis revealed that the severity of paralysis significantly affects neurological recovery in patients with MESCC. Patients with MESCC should receive surgery before the preoperative ASIA Impairment Scale grade falls below grade C. No potential conflict of interest relevant to this article was reported.

Okayama University Medical School Acta Medica Okayama 0386-300X 68 5 2014 A Rare Course of Scoliosis Associated with Chiari Malformation and Syringomyelia 303 306 EN Masato Tanaka Yoshihisa Sugimoto Shinya Arataki Tomoyuki Takigawa Toshifumi Ozaki Case Report 10.18926/AMO/52899 Spinal deformity is an important clinical manifestation of Chiari I malformation (CM-I) and syringomyelia. Here we report the result of an 8-year follow-up of a 13-year-old girl with severe scoliosis associated with Chiari malformation and a large syringomyelia. The patient presented at our hospital at the age of 13 with a 68° scoliosis. Magnetic resonance imaging showed Chiari malformation and a large syringomyelia. Neurosurgical treatment involved foramen magnum decompression and partial C1 laminectomy, but the scoliosis still progressed. We present the first case report of a rare course of scoliosis in a patient with CM-I and a large syringomyelia. No potential conflict of interest relevant to this article was reported.

Okayama University Medical School Acta Medica Okayama 0386-300X 67 6 2013 Chiari Type I Malformation Caused by Craniometaphyseal Dysplasia 385 389 EN Masato Tanaka Shinya Arataki Yoshihisa Sugimoto Tomoyuki Takigawa Tomoko Tetsunaga Toshifumi Ozaki Case Report 10.18926/AMO/52012 Craniometaphyseal dysplasia is a rare genetic condition characterized by progressive thickening of bones in the skull and metaphyseal abnormalities in the long bones. This disorder often causes progressively symptomatic cranial nerve compression, but in rare cases foramen magnum stenosis may lead to quadriplegia. Chiari I malformation with craniometaphyseal dysplasia is extremely rare. The authors report on a 25-year-old woman with myelopathy due to Chiari I malformation along with craniometaphyseal dysplasia. There are only four previous case reports of this condition. The authors present here the fifth case report of this rare condition and summarize its characteristics. No potential conflict of interest relevant to this article was reported.

Okayama University Medical School Acta Medica Okayama 0386-300X 67 6 2013 Factors Predicting Clinical Impairment after Surgery for Cervical Spinal Schwannoma 343 349 EN Kentaro Yamane Tomoyuki Takigawa Masato Tanaka Syuhei Osaki Yoshihisa Sugimoto Toshifumi Ozaki Original Article 10.18926/AMO/52007 Cervical spinal schwannoma is benign, and outcomes after surgical resection are generally excellent. A surgical dilemma sometimes arises as to whether to perform total tumor removal, which carries a risk of sacrificing the nerve root, or subtotal removal, where the risk can be tumor recurrence. The purpose of this study was to identify factors with the potential to predict clinical impairment after surgery for cervical spinal schwannomas. Thirty cases of cervical schwannomas treated surgically in our institute were retrospectively reviewed;initial symptoms, tumor location, Eden classification, surgical method, functional outcome, and tumor recurrence were investigated. All permanent motor deficits were the result of resecting functionally relevant nerve roots (i.e., C5-8). The rate of permanent sensory deficit was 11% after C1-4 nerve root resection, and 67% after C5-8 nerve root resection. Permanent neurological deficits occurred in 14% of patients younger than 40 years and 38% of those older than 40. Dumbbell tumors were associated with the need for total or ventral nerve root transection, as well as with a high incidence of tumor recurrence. The incidence of permanent neurological deficit was significantly higher in patients undergoing C5-8 nerve root resection, and tended to be higher in those over 40. No potential conflict of interest relevant to this article was reported.

Okayama University Medical School Acta Medica Okayama 0386-300X 66 4 2012 Segmental Pedicle Screw Fixation for a Scoliosis Patient with Post-laminectomy and Post-irradiation Thoracic Kyphoscoliosis of Spinal Astrocytoma 363 368 EN Masato Tanaka Yoshihiro Sugimoto Haruo Misawa Tomoyuki Takigawa Toshiyuki Kunisada Toshifumi Ozaki Case Report 10.18926/AMO/48692 Spinal deformity is an important clinical manifestation after surgery for spinal cord tumors. One-third of patients who receive laminectomies and irradiation of the spinal column develop scoliosis, kyphosis, or kyphoscoliosis. Recent reports indicate good results after scoliosis surgery using segmental pedicle screws and a navigation system, but these reported studies have not included surgery for post-laminectomy kyphosis. Hooks and wires are ineffective in such patients who undergo laminectomy, and there are also high perioperative risks with insertion of pedicle screws because landmarks have been lost. Here, we report on the 5-year follow-up of a 13-year-old male patient with post-laminectomy and post-irradiation thoracic kyphoscoliosis after surgical treatment of spinal astrocytoma. Posterior segmental pedicle screw fixation was performed safely using a computer-assisted technique. The authors present the first case report for treatment of this condition using a navigation system. No potential conflict of interest relevant to this article was reported.