Surgical treatment of a lumbar aneurysmal bone cyst using percutaneous endoscopic lumbar discectomy.

PURPOSE: Aneurysmal bone cysts of the lumbar spine are usually treated by curettage followed by bone or bioactive ceramics grafting. Here, we present the first case of an aneurysmal bone cyst of the lumbar spine treated by percutaneous endoscopic lumbar discectomy (PELD). METHODS: We describe the clinical characteristics of the patient including the radiological and pathological findings of the tumor and the surgical technique used. RESULTS: A 15-year-old boy presented with low back pain, and he was diagnosed with an aneurysmal bone cyst of the L3 vertebra based on radiological findings, including plain radiograph, computed tomography, and magnetic resonance imaging. The technique and equipment of PELD were used to perform curettage of the tumor cavity and fill it with hydroxyapatite granules. The skin incision was only 8 mm. The patient was discharged 1 day postoperatively and could walk without assistance. The postoperative course was uneventful and the symptoms improved following surgery. CONCLUSION: Endoscopic surgery via PELD can be a treatment option for ABCs of the lumbar spine.

Spino-pelvic-rhythm with forward trunk bending in normal subjects without low back pain.

A strong correlation between low back pain and tight hamstrings has been reported. However, the effect of tight hamstrings on spinal biomechanics remains unclear. The purpose of the study was to investigate spino-pelvic-rhythm during forward bending of the trunk and to clarify the rhythm features with regard to hamstrings tightness. Eighteen healthy male adults with no history of low back pain volunteered to participate. First, we measured the finger-to-floor distance (FFD) in the upright position and set this parameter to 100 %. Using a spinal mouse, spinal alignment was measured in the following four positions: (1) upright posture­100 % FFD; (2) forward bending­50 % FFD; (3) forward bending­25 % FFD; and (4) forward bending­0 % FFD (fingers in contact with the floor). Changes of the angle of the thoracic and lumbar spine as well as the pelvis were calculated. As an indicator of tight hamstrings, we measured straight leg raising (SLR) angle. From positions 1­2 (phase I), the entire spino-pelvic angle moved in 104°. During this phase, the lumbar spine mainly moved. In the second phase (positions 2­3), it moved in 16°. Interestingly, all but 2 subjects showed a negative angle in the thoracic motion, meaning that the thoracic spine extended 4° during trunk flexion, thus exhibiting paradoxical motion. During this phase, lumbopelvic rhythm showed 2 patterns. In 7 subjects, pelvic motion was greater than lumbar motion, while the remaining subjects showed the opposite. In subjects without tight hamstrings, 83 % showed a pelvis-dominant pattern. Only 7 subjects were capable of position 4. During this phase, only slight motion was noted in the spine, and the majority of the motion occurred in the pelvis. Lumbar and pelvic motion correlated negatively in all phases. SLR angle and pelvic motion correlated strongly during phase III, indicating dominant pelvic movement in flexible subjects. The lumbo-pelvic-rhythm comprises 2 patterns­lumbar dominant and pelvis dominant. In flexible subjects, pelvis movement was dominant. In conclusion, improving tight hamstrings may reduce lumbar loading thereby reducing low back pain.

Spino-pelvic-rhythm with forward trunk bending in normal subjects without low back pain.

A strong correlation between low back pain and tight hamstrings has been reported. However, the effect of tight hamstrings on spinal biomechanics remains unclear. The purpose of the study was to investigate spino-pelvic-rhythm during forward bending of the trunk and to clarify the rhythm features with regard to hamstrings tightness. Eighteen healthy male adults with no history of low back pain volunteered to participate. First, we measured the finger-to-floor distance (FFD) in the upright position and set this parameter to 100 %. Using a spinal mouse, spinal alignment was measured in the following four positions: (1) upright posture-100 % FFD; (2) forward bending-50 % FFD; (3) forward bending-25 % FFD; and (4) forward bending-0 % FFD (fingers in contact with the floor). Changes of the angle of the thoracic and lumbar spine as well as the pelvis were calculated. As an indicator of tight hamstrings, we measured straight leg raising (SLR) angle. From positions 1-2 (phase I), the entire spino-pelvic angle moved in 104°. During this phase, the lumbar spine mainly moved. In the second phase (positions 2-3), it moved in 16°. Interestingly, all but 2 subjects showed a negative angle in the thoracic motion, meaning that the thoracic spine extended 4° during trunk flexion, thus exhibiting paradoxical motion. During this phase, lumbopelvic rhythm showed 2 patterns. In 7 subjects, pelvic motion was greater than lumbar motion, while the remaining subjects showed the opposite. In subjects without tight hamstrings, 83 % showed a pelvis-dominant pattern. Only 7 subjects were capable of position 4. During this phase, only slight motion was noted in the spine, and the majority of the motion occurred in the pelvis. Lumbar and pelvic motion correlated negatively in all phases. SLR angle and pelvic motion correlated strongly during phase III, indicating dominant pelvic movement in flexible subjects. The lumbo-pelvic-rhythm comprises 2 patterns-lumbar dominant and pelvis dominant. In flexible subjects, pelvis movement was dominant. In conclusion, improving tight hamstrings may reduce lumbar loading thereby reducing low back pain.

Histological analysis of nucleus pulposus tissue from patients with lumbar disc herniation after condoliase administration.

Background: Condoliase is an enzyme used as a treatment for lumbar disc herniation (LDH). This enzyme degrades chondroitin sulfate (CS) in the nucleus pulposus of the intervertebral disc (IVD). However, there are cases in which symptoms do not improve, despite condoliase administration. This study reports histological analysis of lumbar disc tissue of LDH patients who underwent surgery because condoliase had no therapeutic effect. Methods: Between March 2019 and August 2019, 12 LDH patients who underwent full endoscopic spine surgery (FESS) discectomy at the Dezawa Akira PED Clinic were the subjects of the study. There are two study groups: six cases underwent FESS after condoliase administration, while six underwent FESS without condoliase administration. The average duration from drug administration to surgery was 152 days. Herniated disc removed at surgery was evaluated by histological staining including immunohistochemistry by anti-CS antibodies. Results: Multiple large clusters (40-120 µm in diameter) were observed in the nucleus pulposus of those who received condoliase, but no clusters were observed in those who did not. The lumbar disc tissues, including the nucleus pulposus of recipients, were stained with anti-CS antibodies that recognize the CS unsaturated disaccharide, but non-administration tissue was not stained. These findings suggest that the enzyme acted on the nucleus pulposus, even in cases where symptoms were not improved by condoliase administration. Furthermore, there was no histological difference between stained images of the extracellular matrix in those who did or did not receive condoliase, suggesting that condoliase acted specifically on CS in the nucleus pulposus. Conclusions: We demonstrated that CS in the nucleus pulposus was degraded in patients in whom condoliase did not have a therapeutic effect. Moreover, condoliase acts in human IVD without causing necrosis of chondrocytes and surrounding tissues.

Full-Endoscopic Posterior Lumbar Interbody Fusion: A Review and Technical Note.

Remarkable innovations in spinal endoscopic surgery have broadened its applications over the past 20 years. Full-endoscopic fusions have been widely reported, and several full-endoscopic approaches for interbody fusion have been published. In general, full-endoscopic lumbar interbody fusion (LIF) is called Endo-LIF, and facet-preserving endo-LIF through the transforaminal route is called trans-Kambin's triangle LIF, which has a relatively longer history than facet-sacrificing endo-LIF via the posterolateral route. Both approaches can reduce intraoperative and postoperative bleeding. However, there is a higher risk of subsidence and exit nerve root injury. There is no direct decompression in either of the interbody fusions, and additional decompression is required if there is severe lumbar bony canal stenosis. However, the posterior interlaminar approach, which is a well-known standard in full-endoscopic spine surgery, has rarely been applied in the field of endoscopic lumbar fusion surgery. Full-endoscopic posterior LIF (FE-PLIF) via an interlaminar approach can accomplish direct decompression of bony canal stenosis and safe interbody fusion. FE-PLIF via an interlaminar approach demonstrated a longer operation time, less blood loss, and shorter hospitalization duration than minimally invasive transforaminal LIF. FE-PLIF, which can accomplish direct decompression for bony spinal canal stenosis, is superior to other Endo-LIFs. However, FE-PLIF requires technical dexterity to improve efficiency and reduce technical complexity.

Jack-knife stretching promotes flexibility of tight hamstrings after 4 weeks: a pilot study.

Tight hamstrings are reported to be one of the causes of low back pain. However, there have been few reports on effective stretching procedures for the tight hamstrings. The so-called jack-knife stretch, an active-static type of stretching, can efficiently increase the flexibility of tight hamstrings. To evaluate hamstring tightness before and after the 4-week stretching protocol in healthy volunteer adults and patients aged under 18 years with low back pain. For understanding the hamstrings tightness, we measured two parameters including (1) finger to floor distance (FFD) and (2) pelvis forward inclination angle (PFIA). Eight healthy adult volunteers who had no lumbar or hip problems participated in this study (mean age: 26.8 years). All lacked flexibility and their FFD were positive before the experiment. Subjects performed 2 sets of the jack-knife stretch every day for 4 weeks. One set consisted of 5 repetitions, each held for 5 s. Before and during the 4-week experiment, the FFD and PFIA of toe-touching tests were measured weekly. For 17 of the sports players aged under 18, only FFD was measured. In adult volunteers, FFD was 14.1 ± 6.1 cm before the experiment and decreased to -8.1 ± 3.7 cm by the end of week 4, indicating a gain in flexibility of 22.2 cm. PFIA was 50.6 ± 8.2 before the experiment and 83.8 ± 5.8 degrees after. Before and after the experiment, the differences were significant (p < 0.05). For those aged under 18, FFD was 8.1 ± 8.0 and -9.6 ± 6.8, before and after the stretching, respectively. This difference was significant (p < 0.05). The jack-knife stretch is a useful active-static stretching technique to efficiently increase flexibility of tight hamstrings.

Two types of laminolysis in adolescent athletes.

Bony defects in the spine are divided into three main types: spondylolysis, pediculolysis, and laminolysis. Lumbar spondylolysis is a well-known stress fracture that occurs frequently in adolescent athletes. Pediculolysis means stress fracture of the pedicle, which sometimes occurs subsequent to unilateral spondylolysis. Laminolysis is a rarely reported stress fracture similar to spondylolysis and pediculolysis that sometimes causes low back pain (LBP). However, its pathomechanism has not been elucidated. Recently, we encountered four adolescent athletes with symptomatic laminolysis. Mean age was 15.8 (range 15-17) years. All subjects reported severe LBP exacerbated by extension of the lumbar spine, and radiology revealed two types of laminolysis: hemilaminar type and intralaminar type. To elucidate the mechanisms of each type, we reviewed a biomechanical study, and found that the hemilaminar type was thought to be subsequent to contralateral spondylolysis, while the intralaminar type might be a result of a stress fracture due to repetitive extension loading.

Modic type I changes of the lumbar spine in golfers.

Low back pain (LBP) is the most prevalent musculoskeletal complaint among professional and amateur golfers; however, associated radiological changes in golf-related LBP have not been examined in the literature. We suspect that Modic Type 1 changes in the lumbar spine are linked to golf-related LBP. In this retrospective case series, four middle-aged golfers (one professional and three high-level amateurs) presented to our clinic with LBP. Inflammation of the right side of endplates in the lumbar spine was suspected based on Modic Type 1 changes detected by magnetic resonance imaging (MRI) in each patient. All four cases were diagnosed with right-sided endplate inflammation and administered intradiscal steroid injections with a non-steroidal anti-inflammatory drug (NSAID). Treatment swiftly alleviated LBP and diminished Modic Type 1 changes on follow-up MRI 3-6 months later in all four patients. We suggest that Modic Type 1 changes play a significant role in the diagnosis and treatment of golf-related LBP.

Painful lumbar spondylolysis among pediatric sports players: a pilot MRI study.

INTRODUCTION: For children and adolescents who are very active athletes, fresh lumbar spondylolysis is the main pathologic cause of lower back pain (LBP). However, regarding the terminal-stage spondylolysis (pars defect), there have been few studies to clarify the pathomechanism of LBP. The purpose of this study is to clarify the cause of LBP associated with pars defects in athletes. This is the first report showing a possible pathomechanism of LBP in active athletes with painful pars defect. METHOD: Six pediatric athletes (5 boys and 1 girl) below 18 years old with painful bilateral lumbar spondylolysis were evaluated. In all cases, spondylolysis was identified as terminal stage (pseudoarthrosis) on CT scan. To evaluate the inflammation around the pars defects, short time inversion recovery (STIR) MRI was performed along with the sagittal section. Fluid collection, which is an indicator of inflammatory events, was evaluated in 12 pars defects as well as in 12 cranial and caudal adjoining facet joints. RESULTS: Inflammation (i.e., fluid collection) was observed in all 12 pars defects in six subjects at the pseudoarthrotic pars defects. In terms of facet joints, 7 of 12 (58%) pars defects showed fluid collection at the cranial and/or caudal adjoining joints on STIR MRI. CONCLUSION: The present study showed that inflammation was always present at the pars defects and in some cases at the adjoining facet joints. Thus, it is not difficult to understand how, during sports activity, inflammation may first occur at the pseudoarthrotic site and then spread to the adjoining facet joints. This mechanism could cause LBP associated with terminal-stage (pseudoarthrotics) spondylolysis in athletes.

Incidence of complications associated with spinal endoscopic surgery: nationwide survey in 2007 by the Committee on Spinal Endoscopic Surgical Skill Qualification of Japanese Orthopaedic Association.

BACKGROUND: This report was conducted to elucidate the current status of spinal endoscopic surgery and relevant incidents through analysis of the results of a questionnaire survey conducted in 2007 by the Committee on Spinal Endoscopic Surgical Skill Qualification of the Japanese Orthopaedic Association (JOA). METHODS: Questionnaire forms were sent to 2011 training facilities nationwide certified by the JOA, and 1082 of these facilities returned the filled questionnaires (response rate 53.8%). Of these facilities, 257 (23.8% of the responding facilities) undertook spinal endoscopic surgery in 2007. These institutions were asked to fill in the survey form with the details of the operations and relevant incidents as well as the incident levels. RESULTS: In total, the 257 facilities performed 6239 spinal endoscopic surgeries during 2007. Posterior spinal endoscopic surgery constituted most of the operations (6217 cases, 98.2%) including 4336 cases of microendoscopic discectomy (MED), 1273 cases of microendoscopic laminectomy or fenestration, and 379 cases of transforaminal or posterior lumbar interbody fusion. The total number of incidents was 133 (2.13%). The numbers of incidents by operative method were 75 (56.4%) during MED, 57 (42.9%) during microendoscopic laminectomy or fenestration, and 1 (0.8%) during interbody fusion. Of 133 incidents, dural tear occurred in 99 (74.4%), injury of the cauda equina or a nerve root in 7 (5.3%), facet fracture in 7 (5.3%), hematoma and wrong level in 6 each (4.5%), and wrong side and bedsore in 1 each (0.8%). The incident level was level 1 in 6, level 2 in 24, level 3a in 82, level 3b in 16, level 4 in 5, and level 5 (fatal) in 0. CONCLUSIONS: The results of this survey revealed an increasing trend of spinal endoscopic surgery and a decreasing trend of the complication rates. The complication rates of spinal endoscopic surgery were not higher than those of conventional surgery, indicating the safety of this surgical method.

[Development of percutaneous endoscopic approach for lumbar disc herniations].

"Primum nil nocere" (minimally invasive procedure) has been the perennial pursuit for surgeons since the time of Hippocrates. However, due to the recent advancement of optical technology and the development of related devices, a remarkable progress has been made in lumbar discectomy by using minimally invasive surgery. By minimizing not only skin incision but also approach related morbidity, an adverse effect to the nerve root can be reduced to the minimum. And day surgery (outpatient surgery, same day surgery, ambulatory surgery) hastens patients' return to normal life. In the U.S., outpatient surgery has grown in popularity since Medicare's introduction of prospective payment system of in-hospital treatment in 1983. As for lumbar disc surgery, a surgical technique which is applicable to the disc herniation at a high location or a traverse section has been developed. This procedure is conducted under either local or general anaesthesia and designed to take the pressure off the nerve root by directly excising the disc that is pushing against the nerve root. The surgery can be done on an outpatient basis or with one overnight stay in the hospital, and most patients can be released from the hospital within 24 hours. This is a technique called percutaneous endoscopic lumbar discectomy (PELD) and the disc can be dissected from lateral intervertebral foramen or between the interlaminar window of vertebrae. PELD originated from percutaneous nucleotomy devised by Hijikata et al. in 1975 and the introduction of endoscopic technique has enabled the direct approach to the lumbar disc herniation, located further posteriorly than nucleus pulposus. It is not an exaggeration to say that this technique was created in Japan. Minimal damage to posterior longitudinal ligament and bones would reduce the postsurgical instability. The procedure is also advantageous in preventing lumbar facet syndrome and vertebral canal stenosis. The patients' satisfaction rate is high in terms of postoperative recovery and the usage of NSAID, and compared to microscopic discectomy and MED technique, PELD can be considered as less invasive surgical technique for lumbar disc herniation. This technique makes the most of the space within the intervertebral foramen where, as Kambin claimed, the safe approach to the lesion is possible. As we make the skin incision more medially than reported before in order to approach the intervertebral foramen at a steep angle, the occurrence of exiting nerve lesion at a superior location has decreased. This surgical method would be a promising alternative to MED technique as well as microscope-assisted technique.

In Vitro Study of the Effects of Denosumab on Giant Cell Tumor of Bone: Comparison with Zoledronic Acid.

Giant cell tumor of bone (GCTB) is a locally aggressive primary bone tumor that contains numerous osteoclasts formed from marrow-derived precursors through receptor activator of nuclear factor κ-B ligand (RANKL), an osteoclast differentiation factor expressed in neoplastic cells of GCTB. Denosumab, a fully human monoclonal antibody targeting RANKL, has recently been used for the treatment of GCTB, and superior treatment effects have been reported. The aim of this work was to elucidate the mechanism of action of denosumab, and the differences between denosumab and zoledronic acid at the level of GCTB cells. We isolated GCTB cells from 3 patients and separated them into osteoclasts, osteoclast precursors and proliferating spindle-shaped stromal cells (the true neoplastic component), and examined the action of denosumab on differentiation, survival and bone resorption activity of osteoclasts. Denosumab and zoledronic acid inhibited osteoclast differentiation from mononuclear cells containing osteoclast precursors. Zoledronic acid inhibited osteoclast survival, whereas an inhibitory effect of denosumab on osteoclast survival was not observed. The inhibitory effect on bone resorption by both agents was confirmed in culture on dentin slices. Furthermore, zoledronic acid showed dose-dependent inhibition of cell growth of neoplastic cells whereas denosumab had no inhibitory effect on these cells. Denosumab has an inhibitory effect on osteoclast differentiation, but no inhibitory effects on survival of osteoclasts or growth of neoplastic cells in GCTBs.

Endoscopic decompression combined with interspinous process implant fusion for lumbar spinal stenosis.

OBJECTIVE: To propose a new technique to treat lumbar spinal stenosis with median approach endoscopic decompression combined with interspinous process implant fusion and evaluate the initial clinical outcome. METHODS: This study involved 30 patients who had neurogenic commitment claudication over 2 years and were resistant to conservative therapy. All cases were treated using the median approach endoscopic decompression combined with interspinous process implant fusion in 2006. Clinical signs and radicular pain were noted and evaluated preoperatively and at the 1st month and 3rd month postoperatively. Japanese Orthopedic Association (JOA) score was used to evaluate leg and back pain. X-ray films at flexion and extension were applied to evaluate the range of motion at involved segments. RESULTS: There was a significant increase in JOA score postoperatively, but no significant difference preoperatively or postoperatively between the two groups.The range of motion at involved segments was significantly higher in the control group. CONCLUSIONS: The median approach endoscopic decompression is an ideal method for bilateral radiculopathy resulting from lumbar spinal canal stenosis. The combination with interspinous process implant fusion can stabilize the spine.The initial clinical outcome is exllent. Preservation of adjacent level disease can be assessed only in long-term follow-up.

Clinical study of a new approach to thoracolumbar surgery.

OBJECTIVE: The conventional approaches for treatment of thoracolumbar diseases require extensive surgical exposure, often leading to postoperative pain and morbidity. Thoracoscopic-assisted surgery in these regions usually requires an extended recovery period due to the placement of drainage. We developed an innovative retroperitoneal-extrapleural approach to thoracolumbar involvement by an extra-diaphragmatic technique using dedicated instruments. Neither incision nor reconstruction of the diaphragm was necessary. Exposure to the lateral part of the thoracolumbar vertebrae could be achieved without crus resection. This study is aimed to evaluate the clinical outcomes of this new surgical procedure. METHODS: A total of 9 cases (5 cases of thoracolumbar fracture-dislocation, 1 each of spinal infection, tumor, thoracolumbar scoliosis and ossification of posterior longitudinal ligament) were subjected to the study. The average age of the patients was 52.3 years. The results were compared with the control group consisting of thoracoscopic surgery subgroup (5 patients, mean age 52.1 years) and conventional surgery subgroup (12 patients, mean age 61.3 years). RESULTS: Compared with the control group, the average period of bed confinement and mean intra- and postoperative blood loss decreased significantly. Pulmonary complications were avoided in all cases. The surgical time was shortened, postoperative pain was reduced, and early postoperative ambulation became possible. CONCLUSION: The diaphragm-preserving retroperitoneal-extrapleural approach that we developed is a valid minimally invasive alternative for the treatment of thoracolumbar diseases.

Etiology of Adult-onset Stress Fracture in the Lumbar Spine.

STUDY DESIGN: This study was a case series. OBJECTIVE: The purpose of this paper was to present a case series of fresh stress fractures (spondylolysis) in the lumbar spines of adult athletes. SUMMARY OF BACKGROUND DATA: Lumbar spondylolysis is a stress fracture of the pars interarticularis, which is generally considered a disease of children or adolescence. There is only 1 case series written in English reporting on adult-onset fresh spondylolysis. METHODS: Eleven patients aged 20-27 years are included in this case series. A retrospective analysis was made of events that may cause stress fracture such as traumatic episodes or sports activities, spinal level, radiologic findings, stage of spondylolysis, treatment, and prognosis. RESULTS: Among the 11 patients, two had bilateral early-stage spondylolysis, 7 had unilateral early-stage spondylolysis and 2 had unilateral progressive-stage spondylolysis. Three occurred subsequent to a preexisting terminal-stage spondylolysis in the contralateral side, 1 occurred subsequent to a terminal-stage spondylolysis at the adjacent spinal level, and 1 occurred subsequent to a terminal-stage spondylolysis at a distant level. Thirteen pedicles adjacent to the pars interarticularis in the 11 patients showed bone marrow edema-like signal on magnetic resonance imaging. Six spondylolyses were found at L5, 2 each at L3 and L4, and 1 spondylolysis at L2. The 11 patients were divided into 4 groups according to suspected pathogenic mechanism: preexistent spondylolysis in the contralateral side, alteration of the athletic event, apparent traumatic episode, and others. Conservative treatment was prescribed for return to sports in all cases. Although 1 patient retired because of persistent low back pain, the remaining 10 patients returned to competition. CONCLUSIONS: Although lumbar spondylolysis is generally recognized to occur in childhood or adolescence, fresh lumbar spondylolysis should be included in the differential diagnosis of adult low back pain when patients are high-level athletes. Conservative treatment should be attempted for adult patients.

Arthroscopic release of the piriformis muscle under local anesthesia for piriformis syndrome.

We developed a minimally invasive technique of releasing the piriformis muscle under endoscopic control for entrapment neuropathy of the sciatic nerve because of tension and contraction of the piriformis muscle. This surgical technique was performed in patients who fulfilled at least 5 of 9 diagnostic criteria we established and who did not respond to conservative therapy for 6 months or more. Although a cavity was maintained using a disposable syringe (10 mL) with a cut tip, an arthroscope (4 mm in diameter) was inserted at an oblique viewing angle of 30 degrees, and the muscle was identified. The area from the musculotendinous junction to the muscle was gradually incised using a special scraper. In particular, pain disappeared simultaneously with release of the piriformis muscle during surgery. With this technique, an adequate cavity can be produced and maintained in a manner similar to that in posterior endoscopic surgery for intervertebral disc herniation. This technique is useful for reducing postoperative pain and allows early return to activity.

Comparison of organic electroluminescence and liquid crystal displays for clinical utility in orthopedic endoscopic surgery.

INTRODUCTION: Organic electroluminescence displays (OELD) use organic materials that self-emit light with the passage of an electric current. OELD provide high contrast, excellent color reproducibility at low brightness, excellent video images, and less restricted viewing angles. OELD are thus promising for medical use. This study compared the utility of an OELD with conventional liquid crystal displays (LCD) for imaging in orthopedic endoscopic surgery. METHODS: One OELD and two conventional LCD that were indistinguishable in external appearance were used in this study. Images from 18 patients were displayed simultaneously on three monitors and evaluated by six orthopedic surgeons with extensive surgical experience. Images were shown for 2 min, repeated twice, and viewed from the front and side (diagonally). Surgeon rated both clinical utility (12 parameters) and image quality (11 parameters) for each image on a 5-point scale: 1, very good; 2, good; 3, average; 4, poor; and 5, very poor. RESULTS: For clinical utility in 16 percutaneous endoscopic discectomy cases, mean scores for all 12 parameters were significantly better on the OELD than on the LCD, including organ distinguishability (2.1 vs 3.2, respectively), lesion identification (2.2 vs 3.1), and overall viewing impression (2.1 vs 3.1). For image quality, all 11 parameters were better on the OELD than on LCD. Significant differences were identified in six parameters, including contrast (1.8 vs 2.9), color reproducibility in dark areas (1.8 vs 2.9), and viewing angle (2.2 vs 2.9). CONCLUSION: The high contrast and excellent color reproducibility of the OELD reduced the constraints of imaging under endoscopy, in which securing a field of view may be difficult. Distinguishability of organs was good, including ligaments, dura mater, nerves, and adipose tissue, contributing to good stereoscopic images of the surgical field. These findings suggest the utility of OELD for excellent display of surgical images and for enabling safe and highly accurate endoscopic surgery.

Assessment of maximal insertional torque of cervical and thoracic screws during posterior spinal surgery.

STUDY DESIGN: Multicenter intraoperative biomechanical analysis. PURPOSE: This study aimed to assess the maximal insertional torque (MIT) of lateral mass screw (LMS) and pedicle screw (PS) in the cervical or thoracic vertebrae during surgery. METHODS: During posterior spinal fusion, cervical or thoracic multi-axial screws were placed at different cervical or thoracic levels and the MIT was recorded for each screw revolution using an analogue torque wrench. Screw number was as follows: 11 PS at C7, 134 LMS (C3-6) (Magerl technique, 70; Roy-Camille technique, 64), and 33 PS in the thoracic region. RESULTS: Average MIT values (cNm) were as follows: for PS (diameter: 3.5 mm) at C7, 45.3 ± 21.9 in men and 60.0 ± 20.1 in women (p=0.28); for Magerl screws, 69.0 ± 20.5 in men and 58.6 ± 15.7 in women (p=0.13); and for Roy-Camille screws, 51.0 ± 17.9 in men and 42.4 ± 15.9 in women (p=0.52). The average MIT for Magerl screws was significantly higher than that for Roy-Camille screws in men and women (both p<0.01). CONCLUSIONS: Intraoperative insertional torque could be a good indicator to evaluate the purchase and help guide decisions on screw type and insertion technique. Further postoperative assessments with sequential X-rays are needed to reveal the significance of MIT during posterior spinal fusion.

Persistent tight hamstrings following conservative treatment for apophyseal ring fracture in adolescent athletes: critical appraisal.

Apophyseal ring fracture is a unique disease in children and adolescents. Its clinical features include low back pain, sciatica, paravertebral muscle spasm and tenderness, restricted back motion, neurological symptoms, and tight hamstrings. For all athletes, body flexibility is one of the most important factors for better performance. Therefore, persistent tight hamstrings has a negative influence on athletic performance. In this report, we present two adolescent athletes with apophyseal ring fracture treated successfully by conservative treatment for severe low back pain (LBP) and leg pain, despite having persistent tight hamstrings for more than one year. Unlike herniated nucleus pulposus, bony fragments in the spinal canal never disappear. Although conservative treatment can alleviate LBP and leg pain, surgical removal of fragments is considered when symptoms such as tight hamstrings and restricted lumbar motion due to canal stenosis are found, particularly in athletes.

State of the art: Transforaminal approach for percutaneous endoscopic lumbar discectomy under local anesthesia.

Minimally invasive percutaneous endoscopic discectomy (PED) with a transforaminal approach under local anesthesia was started in the late 20th century. As the procedure requires a skin incision of only 8 mm, it is the least invasive disc surgery procedure at present, and owing to advances in instruments and optics, the use of this technique has gradually spread. In Japan, Dr. Dezawa from Teikyo University Mizonokuchi Hospital introduced this technique in 2003. Thanks to his efforts, the number of surgeons who can perform PED has increased, although the number of active PED surgeons is still only around 20. The first author (K.S.) started PED in 2010. In this review article, we explain the state-of-the-art PED transforaminal technique for minimally invasive disc surgery and present three successful cases.