We have developed a cast microfluidic chip for concentration gradient generation that contains a thin (~5 μm^2 crosssectional area) microchannel. Durable 2 μm-high microchannel mold features with a smooth bell-shaped sidewall were fabricated by exposing SU-8 photoresist to diffused 185 nm UV light emitted by a low-cost ozone lamp from the backside of the substrate to ensure sufficient crosslinking of small regions of the SU-8 photoresist. An H-shaped microfluidic configuration was used, in which the thin channel was able to maintain constant diffusion fronts beyond purely static diffusion confirmed with experiment. We also demonstrated the long-term effects of a gradient of nerve growth factor on axon elongation by primary neuronal cells cultured in the microfluidic channel.

Study design : Technical note. Objectives: To present a new spinal shortening technique for tethered cord syndrome. Background : Tethered cord syndrome (TCS) is a debilitating condition of progressive neurological decline. Surgical detethering for TCS is a gold standard. However, symptomatic retethering of TCS has been reported in 5%–50% of patients after initial release. To solve this problem, posterior spinal shortening osteotomy has been reported. This technique has risks of massive blood loss and neurological deterioration. The authors hereby report a new safe spinal shortening technique for tethered cord syndrome. Materials and Methods : A 31-year-old man with gait disturbance was referred to our hospital. After the delivery, he underwent surgical untethering of spinal cord in another hospital. He had hyperreflexia of Achilles tendon reflex and muscle weakness of bilateral legs (MMT 3-4). He also had urinary and bowel incontinence, and total sensory loss below L5.Anteroposterior lumbar radiogram indicates partial laminectomy of L3 and L4. Lumbar MRI showed retethering of spinal cord. Results: He underwent new spinal shortening technique for tethered cord syndrome under the guidance of O-arm navigation. First, from anterior approach disectomy from T12 to L3 was performed. Second, from posterior Ponte osteotomy was done from T12 to L3, shorten the spinal column 15 mm. The patient was successfully treated surgically. Postoperative lumbar MRI showed the tension of spinal cord was released. Manual muscle testing results and sensory function of the left leg had recovered almost fully on final follow-up at one year. Conclusions/Level of Evidence: Retethered spinal cord after initial untethering was difficult to treat. This new spinal shortening technique was effective and very safe technique to release the tension of spinal cord. Level V.

Background and Objectives: C-arm free MIS techniques can offer significantly reduced rates of postoperative complications such as blood loss and hospitalization time. Another advantageous long-term aspect is the notably diminished exposure to radiation which is known to cause ma-lignant changes. This study emphasizes that, in some cases of spinal conditions which require a procedural intervention, C-arm free MIS techniques hold stronger indications than open surgeries guided by image intensifier. Materials and Methods: In this research, a retrospective analysis and review of various cervical and thoracic spinal procedures, performed in our hospital, by applying C-arm free techniques. The course of the study explains the basic steps of the procedures and demonstrating postoperative or intra-operative results. For anterior cervical surgery, we performed OPLL resection, while for posterior cervical surgery, we performed posterior fossa decompression for Chiari malformation, minimally invasive cervi-cal pedicle screw fixation (MICEPS) and modified Goel technique with C1 lateral mass screw for atlantoaxial subluxation. Re-garding the thoracic spine, we performed anterior correction for Lenke type 5 scoliosis, and transdiscal screw fixation for DISH fractures. Results: C-arm free techniques are safe procedures that offer precise and high-quality postoperative results by offering sufficient spine alignment and adequate decompression depending on the case. Blood loss, postoperative pain and wound infection are other important aspects of spine surgery that must be always taken into consideration. Conclusions: Navigated C-arm free techniques are safe and precise procedures implemented in the treatment of surgically demanding conditions. They can significantly increase accuracy while decreasing the operative time. They represent the advancement in the field spine surgery and are hailed as the future of the same

Study design :Technical note. Objectives : To present a new unilateral biportal endoscopic technique for lumbar disc herniation without C-arm . Background : Lumbar disc herniation requires surgical intervention when conservative methods fail. Shifts towards minimally invasive percutaneous endoscopic lumbar discectomy, including uniportal and biportal approaches, have been hindered by challenges such as steep learning curves and reliance on radiation-intensive C-arm guidance. Our study introduces the use of standard intraoperative navigation in unilateral biportal endoscopy (UBE) to reduce radiation exposure and increase surgical acuracy. Materials and Methods : A 24-year-old man with low back and bilateral leg pain with gait disturbance was referred to our hospital. He had have conservative treatment for 12 months in another hospital before admission. However, the conservative treatment did not work for him. He had low back pain (VAS 4/10) and bilateral leg pain (VAS 8/10), muscle waekness of bilateral legs (Manual muscle testing ;MMT of extensor hullusis longs 4 4), and numbness of bilateral lower leg. Preoperative lumbar MRI showed L4/5 large central disc herniation. Results: He underwent C-arm free unilateral biportal endoscopic discectomy under the guidance of O-arm navigation. The patient was successfully treated surgically. Postoperative lumbar MRI showed good decompression of dural sac and bilateral L5 nerve roots. MMT and sensory function of both leg had recovered fully on final follow-up at one year. Conclusions/Level of Evidence: The new unilateral biportal endoscopic technique under navigation guidance is useful technique for lumbar disc herniation. This innovative technique proved to be safe, accurate, and minimized radiation exposure for surgeons for the treatment of lumbar intervertebral disc herniation. Level V.

The aging of the population in developing and developed countries has lead to a significant increase in health burden of spinal diseases. These elderly patients often have a number of medical co-morbidities due to aging. The need for minimally invasive techniques to address spinal disorders in this elderly population group cannot be stressed enough. Minimally invasive spine surgery (MISS) has several proven benefits such as minimal muscle trauma, minimal bony resection, lesser post-operative pain, decreased infection rate and shorter hospital stay. Over the last 40 years, constant efforts are being made to develop newer techniques of spine surgery. Endoscopic spine surgery is one such subset of MISS which has all the benefits of modern MISS. Endoscopic spine surgery initially was limited only to treatment of lumbar disc herniations. With improvement in optics, endoscopes, endoscopic drills and shavers, irrigation pumps, there has been a paradigm shift. Endoscopic spine surgery can now be performed with high magnification thus allowing its application not only to lumbar spinal stenosis, but also to spinal fusion surgeries, cervical and thoracic pathology as well. There has been increasing evidence in support of these newer techniques of spine surgery. For the purpose of this review, we studied current available literature and outlined the historical evolution of endoscopic spine surgery, the various different endoscopic systems, and techniques available and the current applications of endoscopic techniques as an alternative to traditional spinal surgery.

Study design: Technical note. Objectives: To present a novel technique of treatment for patient with basilar invagination. Background : Basilar invagination (BI) is considered a congenital condition and can compress the cervicomedullary junction, causing neurologic deficit. Severe neurological deficit due to BI should be treated surgically. However, there is controversy regarding whether an anterior or posterior approach should be used. Anterior approach is optimal for decompression of cervicomedullary junction, but this approach has high complication rates. Posterior reduction has a high risk of occipital screws backout and/or instrument failure. Materials and Methods : A 15-year-old boy with severe myelopathy was referred to our hospital. He had neck pain, muscle weakness of bilateral upper limbs, gait disturbance appeared 3 months before he visited our hospital, he drops a cup several times recently. In the examination, he had hyperreflexia of upper and lower limbs and muscle weakness of bilateral arms (MMT 4), hypoesthesis was observed bilaterally below elbow and both legs. He also had clumsiness of bilateral hands, mild urinary and bowel incontinence, and spastic gait. His 10 second grip and release test was 16 in both hands. His grip power was 20 kg in right and 17 kg in left. Radiograms showed severe BI and spinal cord was severely compressed with odontoid process.. Results : The patinet underwent posterior surgery with C-arm free technique. All screws including occipital screws were inserted adequate position under navigation guidance. Reduction was achieved with skull rotation and distraction. A follow-up at one year we have these results : Manual muscle testing results and sensory function tests showed almost full recovery, bilateral arms (MMT 5) ,walking smoothly. Cervical Japanese orthopedic association score of the patient has improved from 9/17 to 16/17. Post-operative images showed an excellent spinal cord decompression, and no major or severe complications has occured . Conclusions/Level of Evidence : Basilar invagination with Klippel-Feil syndrome is relatively rare condition. Posterior approach and occipito-cervical fixation for BI treatment with navigation technique is a safe method to treat severe myelopaty with reducible odontoid. This novel navigation technique provides an excellent results for a patient with BI. Level V.

Study design: Technical note. Objectives: To present a new technique of treatment for a patient with thoracolumbar focal kyphosis due to osteoporotic verte-bral fracture (OVFs). Background : OVFs are common among the elderly population. Following a severe wedged fracture, patients often experience low back pain and disruptions in activities of daily living. Reconstruction surgeries, such as corpectomy, are among the treatment options for this condition. However, corpectomy requires longer surgical times and involves a significant amount of blood loss. Materials and Methods : An 80-year-old woman presented to our hospital with severe low back pain and gait disturbance. She had experienced an L2 OVF six years prior. Although she had no neurological deficit, she could not walk more than 200m due to pain. Preoperative spinal radiographs revealed severe sagittal malalignment, with the L2 vertebra collapsed and focal kyphosis of L1-3 measuring 34 degrees. Results: The patient underwent anterior and posterior surgery in the right decubitus position using a C-arm free technique. The surgical time was 133 minutes with an estimated blood loss of 100 ml. Hyperlordotic cages were inserted in the upper and lower disc space via a lateral approach, while percutaneous pedicle screws (PPS) were inserted from a posterior approach. These procedures were performed simultaneously under navigation guidance only. Post-operative images showed excellent spinal alignment, with local kyphosis reduced from 34 to 14 degrees, and no major or severe complications occurred. At one-year follow-up, the patient was able to walk smoothly, with her visual analogue scale for low back pain improving from 73mm to 13mm, and her Oswestry Disability Index improving from 53.3% to 13.3%. Conclusions/Level of Evidence : The simultaneous use of hyperlordotic cages and PPS is an effective and innovative navigation technique that yields promising outcomes for thoracolumbar focal kyphosis resulting from OVFs. This approach not only reduces surgical time but also minimizes intraoperative blood loss. Level V.

With an increase in proportion of elderly patients, the global burden of spinal disease is on the rise. Likewise, there has been an increasing trend in the number of spine surgeries being performed worldwide. As we know, rehabilitation following spine surgery is critical for optimal recovery. However, current literature lacks consensus regarding the appropriate post operative rehabilitation protocol. The goals of rehabilitation after lumbar spine surgery are to improve physical and psychosocial function and may include multiple modalities such as physical therapy, cognitive behavioral therapy, specialized instruments, and instruction to be followed during activities of daily living. In recent years, not only are a greater number of spine surgeries being performed, various different techniques of lumbar spine surgery and spinal fusion have emerged. Physical therapy programs need to be curated after assessing the functional status of the patient by using various patient reported outcome measures and taking into consideration the technique of spinal fusion used and the muscle groups involved in these surgeries. By doing so it is possible to assess the level of functional impairment and then specifically target strengthening of those muscle groups affected by surgery whilst also improving impaired balance and allowing return to activities of daily living. We reviewed available literature pertaining to the history of spinal rehabilitation, the popular patient reported outcome measures used and different rehabilitation methods with the purpose of summarizing the current guidelines for postoperative rehabilitation after spine surgery and to introduce the rehabilitation after lumbar surgeries that we provide at our hospital.

Study design: Retrospective cohort study. Objectives: To investigate the outcomes of early ballon kyphoplasty (BKP) intervention compared with late intervention for osteoporotic vertebral fracture. Background: Osteoporotic vertebral fractures, can lead to kyphotic deformity, severe back pain, depression, and disturbances in activities of daily living (ADL). BKP has been widely utilized to treat symptomatic OVFs and has proven to be a very effective surgical option for this condition. BKP is relatively a safe and effective method due to less acrylic cement leakage and greater kyphosis correction. Materials and Methods: A retrospective comparative study was conducted at our hospital for patients who underwent BKP for osteoporotic vertebral fractures in the time frame between January 2020 and December 2022. Ninety-nine patients were included in this study, patients were classified into two groups: 36 patients underwent early BKP intervention (EI)