Published papers

Introduction: A lumbar discal cyst is a relatively rare cystic lesion that communicates with lumbar intervertebral discs. Surgical resection of the cyst is the reported treatment of choice. In this study, the authors report the minimally invasive surgical resection of lumbar discal cysts using a microendoscopy. Patients and Methods: Seven male patients with lumbar discal cysts underwent microendoscopic resections (mean age: 25.1?3.2 years and the mean follow-up period: 27.9 months). During the surgeries, the cysts were subtotally resected in a piecemeal fashion, and the fistulas forming the communications between the cysts and the corresponding intervertebral discs were coagulated using a bipolar coagulator. Results: All the patients obtained relief from their pain after surgery, and no recurrences occurred during a mean follow-up period of 28 months. The mean operation time was 72.6?20.2min, and the mean blood loss was 44.4?13.7 grams. No intra- or peri-operative complications were noted in any of the patients. Conclusions: Microendoscopic resection appears to be a minimally invasive and feasible surgical option for the treatment of lumbar discal cysts. © Georg Thieme Verlag KG Stuttgart.

Study Design. Prospective clinical series. Objective. To determine how many thoracic scoliotic pedicles have cancellous versus cortical versus absent channels. Summary of Background Data. Although morphologic evaluations of thoracic pedicles have been well reported, the results do not practically reflect clinical findings during actual pedicle screw placement. We propose a novel pedicle channel classification describing the osseous anatomy encountered during pedicle probe insertion. Methods. We noted 4 pedicle types in 53 consecutive scoliosis patients. Type A: pedicle probe smoothly inserted without difficulty; the morphology is described as a "Large Cancellous Channel." Type B: pedicle probe inserted snugly with increased force; described as a "Small Cancellous Channel." Type C: pedicle probe cannot be manually pushed but must be tapped with a mallet down the pedicle into the body; described as a "Cortical Channel." Type D: pedicle probe cannot locate a channel thus necessitating a "juxtapedicular" screw position; described as a "Slit/Absent Channel." The average age at time of surgery was 23.4 ± 16.7 years. Diagnoses included idiopathic scoliosis (n = 38) and syndromic scoliosis (n = 15). The average main thoracic Cobb angle was 73° ± 26°. Evaluation of pedicle morphology of the 4 types was also performed in 21 consecutive cases of adolescent idiopathic scoliosis using preoperative computed tomography images. Results. A total of 1021 pedicles with screws placed were evaluated. The average percent per type was as follows: 61.0% type A; 29.2% type B, 6.8% type C, and 3.0% type D. On the convexity, 98.2% of pedicles were type A or B versus 81.5% on the concavity (P < 0.05). There were significant differences between adolescent versus adult idiopathic scoliosis (P = 0.007), and syndromic scoliosis versus adult idiopathic scoliosis (P = 0.017) regarding pedicle morphologic proportions. There was a significant tendency toward a decrease in the proportion of type A pedicles, an increase in the proportion of type B pedicles as the Cobb angle increased (P < 0.0001). Evaluation based on 312 thoracic pedicles in 21 consecutive adolescent idiopathic scoliosis patients using preoperative computed tomography axial images confirmed assumptions of the 4 pedicle types. Conclusion. We propose a classification for pedicle channels describing the osseous anatomy encountered during pedicle probe insertion. Based on the classification, surprisingly, we found during surgery that 90% of thoracic pedicles had a cancellous channel, whereas 7% had a cortical channel and only 3% had an absent channel. © 2010, Lippincott Williams & Wilkins.

Object. The aim in this study was to evaluate the efficacy of the ball tip technique in placing thoracic pedicle screws (TPSs), as compared with the conventional freehand technique, in both a cadaveric study and a clinical study of patients with adolescent idiopathic scoliosis. Although posterior spinal surgery using TPSs has been widely applied, these screws are associated with the potential risk of vascular, pulmonary, or neurological complications. To further enhance the accuracy and safety of TPS placement, the authors developed the ball tip technique. Methods. After creating an appropriate starting point for probe insertion, a specially designed ball tip probe consisting of a ball-shaped tip with a flexible metal shaft is used to make a guide hole into the pedicle. Holding the probe with the fingertips while using an appropriate amount of pressure or by tapping it gently and continuously with a hammer, one can safely insert the ball tip probe into the cancellous channel in the pedicle. In a cadaveric study, 5 spine fellows with similar levels of experience in placing TPSs applied the ball tip or the conventional technique to place screws in 5 cadavers with no spinal deformities. The incidence of misplaced screws was evaluated by dissecting the spines. In a clinical study, 40 patients with adolescent idiopathic scoliosis underwent posterior surgery with TPS placement via the ball tip or conventional technique (20 patients in each treatment group). The accuracy of the TPS placements was evaluated on postoperative axial CT scanning. Results. In the cadaveric study, 100 TPSs were evaluated, and the incidence of misplaced screws was 14% in the ball tip group and 34% in the conventional group (p = 0.0192). In the clinical study, 574 TPSs were evaluated. One hundred seventy-one intrapedicular screws (67%) were recognized in the conventional group and 288 (90%) in the ball tip group (p < 0.01). In the conventional and ball tip groups, the respective numbers of TPSs with a pedicle breach of ≤ 2 mm were 20 (8%) and 15 (5%), those with a pedicle breach of > 2 mm were 32 (13%) and 9 (3%; p < 0.01), and those located in the costovertebral joints were 32 (13%) and 7 (2%). Conclusions. In both cadaveric and clinical studies the ball tip technique enhanced the accuracy of TPS placement as compared with the conventional freehand technique. Thus, the ball tip technique is useful for the accurate and safe placement of TPSs in deformed spines.

Study Design: A prospective 10-year follow-up study of patients with whiplash-associated disorders (WAD) and asymptomatic volunteers. Objective: To clarify long-term impact of whiplash injury on patient's symptoms and on magnetic resonance imaging (MRI) findings of the cervical spine. Summary of background data: Long-term prognosis of WAD has not been fully elucidated. Methods: Between 1993 and 1996, we conducted cross-sectional comparative study of 508 acute WAD patients and 497 asymptomatic volunteers, all of whom underwent MRI of the cervical spine. For this follow-up study, 133 WAD patients and 223 control subjects were recruited again. All participants underwent follow-up MRI and physical examination, and answered to questionnaires regarding neck symptoms. Evaluation of MRI included decrease in signal intensity of discs, posterior disc protrusion, disc space narrowing, and foraminal stenosis using 2 to 4 numerical grades. Increase in the numerical grades by one or more was considered to be progression of degenerative changes. Results: Progression of decrease in signal intensity was observed in 109 WAD patients (82.0%), and 132 control subjects (59.2%), (age, sex adjusted odds ratio [OR]: 3.06), posterior disc protrusion in 101 (75.9%) and in 155 (69.5%) (OR = 1.46), disc space narrowing in 33 (24.8%) and in 59 (26.5%) (OR = 0.98), and foraminal stenosis in 6 (4.5%), and in 20 (9.0%) (OR = 0.52), respectively. Neck pain was observed in 34 WAD patients (25.6%) and 22 control subjects (9.9%) (P < 0.0001). There was no statistically significant correlation between neck pain and progression in each MR finding in either group. Conclusion: The results of this study suggest that, although some WAD patients are more likely to suffer from long-lasting neck pain, MRI findings cannot explain the symptoms. © 2010, Lippincott Williams & Wilkins.

Objective: The role of postmenopause on the pathogenesis of cartilage degeneration has been an open question. We assessed cartilage degeneration in estrogen receptor (ER)α null mice and examined the role of glucocorticoid receptor-interacting protein 1 (GRIP1) in the ERα-dependent transcription of a type II collagen gene (col2a1) with special reference to a crosstalk with the transforming growth factor (TGF)-β signaling pathway. Methods: The vertebral cartilaginous endplate from female ERα null mice was subjected to histological analyses. Col2a1 expression of primary chondrocytes (PCs) obtained from ERα null mice after 17β-estradiol (E2) and TGF-β1 stimulation was examined by reverse transcription polymerase chain reaction (RT-PCR). Estrogen response element (ERE) or col2a1 promoter-enhancer luciferase reporter system was used to investigate the crosstalk among ERα, GRIP1, and MKK6. Col2a1 expression and glycosaminoglycan (GAG) content were measured in ATDC5 cells treated with GRIP1 small interfering RNA (siRNA). Results: ERα deficiency clearly accelerated impairment of the vertebral cartilaginous endplate. E2 and TGF-β1 stimulation increased col2a1 expression in PC from wild-type mice, but not that from ERα null mice. The same stimulation increased the col2a1 promoter-enhancer reporter activity, and the elevated activity was decreased by dominant-negative ERα and p38 mitogen-activated protein kinase (MAPK) inhibitor. GRIP1 increased the E2-dependent ERE activation in the presence of ERα and constitutive-active MKK6. GRIP1 siRNA repressed col2a1 expression and GAG production in ATDC5 cells. Conclusions: Crosstalks between ERα/GRIP1 and TGF-β/MKK6/p38 MAPK pathway have protective roles on cartilage metabolism via regulating the extracellular matrices expression. The finding may lead to the development of a novel therapeutic approach for cartilage degeneration. © 2010 Osteoarthritis Research Society International.

Skeletal fracture healing involves a variety of cellular and molecular events; however, the mechanisms behind these processes are not fully understood. In the current study, we investigated the potential involvement of the signal transducer and activator of transcription 1 (STAT1), a critical regulator for both osteoclastogenesis and osteoblast differentiation, in skeletal fracture healing. Weused a fracture model and a cortical defect model in mice, and found that fracture callus remodeling and membranous ossification are highly accelerated in STAT1-deficient mice. Additionally, we found that STAT1 suppresses Osterix transcript levels and Osterix promoter activity in vitro, indicating the suppression of Osterix transcription as one of the mechanisms behind the inhibitory effect of STAT1 on osteoblast differentiation. Furthermore, we found that fludarabine, a potent STAT1 inhibitor, significantly increases bone formation in a heterotopic ossification model. These results reveal previously unknown functions of STAT1 in skeletal homeostasis and may have important clinical implications for the treatment of skeletal bone fracture. © 2010 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.

Study Design: Retrospective radiographic/imaging study. Objective: To evaluate preoperative and sequential postoperative radiographs following C1-C2 arthrodesis for atlantoaxial subluxation in patients with rheumatoid arthritis (RA) to determine risk factors for the development of subaxial subluxations (SAS). Summary of Background Data: The development of SAS has often been observed after C1-C2 arthrodesis. However, there have been no previous reports on the correlation between radiographic parameters and the incidence of postoperative SAS. Methods: The study group comprised of 58 patients with RA who underwent C1-C2 arthrodesis due to atlantoaxial subluxation. There were 5 men and 53 women with a mean age of 55.8 years. The mean follow-up period was 137 months. Nineteen patients with a postoperative SAS after C1-C2 arthrodesis were classified as the SAS+ group. Other 39 pat ents without a postoperative SAS were included in the SAS- group. Clinical outcomes and plain radiographs were reviewed retrospectively and compared between the 2 groups. Results: The difference between pre- and postoperative atlantoaxial (AA) angles in the SAS+ group was significantly greater than those in the SAS- group (P = 0.039). The C2-C7 angles changed significantly between pre- and postoperative periods in the SAS+ group (P = 0.039), but not in the SAS- group (P = 0.897). It was suggested that a large AA angle and a small C2-C7 angle observed at the early postoperative period were the risk factors for the development of SAS. We also demonstrated that a high incidence of the C3-C4 SAS resulted from excessive bone fusion at the C2-C3. Conclusion: Excessive correction of AA angle is likely to cause loss of cervical lordosis, resulting in the development of postoperative SAS. In addition, extensive bony union at C2-C3 following C1-C2 arthrodesis frequently leads to the development of extensive SAS at the C3-C4. © 2010, Lippincott Williams & Wilkins.

Study Design.: Magnetic resonance imaging (MRI) study on degeneration of the thoracic spine in asymptomatic subjects. Objective.: To investigate the incidence of degenerative MRI findings of the thoracic spine in asymptomatic subjects and to identify factors related to the degeneration of the thoracic discs. Summary of Background Data.: Studies on age-related degenerative changes of the thoracic spine are scarce. Methods.: Ninety-four asymptomatic Japanese volunteers (48 men and 46 women, mean age of 48.0 ± 13.4 years) underwent MRI of the thoracic and cervical spine and filled the questionnaire regarding life styles. The items evaluated on MRI using a numerical grading system were (1) decrease in the signal intensity of the intervertebral discs (DSI), (2) posterior disc protrusion (PDP), (3) anterior compression of the dural sac (ACD), and (4) disc space narrowing. Association between each degenerative MRI finding and several factors, including age, sex, smoking, sports, body mass index, and degeneration of cervical spine was investigated. Results.: Forty-four (46.8%) patients demonstrated positive degenerative MRI findings at 1 or more thoracic intervertebral levels. The percentage of the subjects with positive MRI findings was 37.2% in DSI, 30.9% in PDP, 29.8% in ACD, and 4.3% in disc space narrowing. The percentages of all MRI findings increased with aging. In 85 (90.4%) patients, degenerative MRI findings were positive in the cervical spine. DSI was significantly associated with age (odds ratio, 11.21, 95% confidence interval, 2.70-46.5), PDP with age (3.44, 1.02-16.61), smoking (4.94, 1.55-15.71) and presence of PDP in the cervical spine (4.25, 1.01-17.92), and ACD was associated with smoking (3.99, 1.28-12.44). Conclusion.: Degenerative changes in the thoracic spine on MRI was observed in approximately half of the asymptomatic subjects, whereas their incidences were less frequent than those in the cervical spine. Factors significantly associated with degenerative changes in the thoracic spine included age, smoking, and degeneration in the cervical spine. © 2010, Lippincott Williams & Wilkins.

STUDY DESIGN.: Case report. OBJECTIVE.: To report 3 cases of malignant tumors in the upper cervical spine that were treated surgically by a combination of posterior tumor resection and stabilization and anterior tumor resection through a mandible-splitting approach after failed ion-beam radiation therapy. SUMMARY OF BACKGROUND DATA.: Few clinical reports have described in detail the postoperative complications associated with transoral surgical resection of tumors in the upper cervical spine after unsuccessful ion-beam radiation therapy. METHODS.: Three patients with malignant tumors in the upper cervical spine who had undergone ion-beam radiotherapy and experienced tumor recurrence were treated by a combination of posterior and anterior surgery through a mandible-splitting approach. One patient (patient 1, a 32-year-old man) had a hemangioendothelioma at the C2 and C3 level, whereas the other 2 patients (patient 2, a 66-year-old woman and patient 3, a 65-year-old man) had a chordoma at the C2 and C3 level. RESULTS.: The intralesional but macroscopic total resection of the tumors was achieved in all 3 patients. However, serious complications developed after surgery, including deep wound infection, cerebrospinal fluid leakage, and meningitis in patient 1, prolonged swallowing difficulty, subsidence of the strut graft, and recurrence in patient 2, and deep wound infection and discitis causing progressive paralysis in patient 3. All patients underwent salvage surgery, including debridement of the wound in patient 1, posterior reinforcement using instrumentation and posterior tumor resection for the recurrent tumor in patient 2, and anterior debridement of the wound with a pedicle flap using the pectoral major muscle in patient 3 to address these problems. Patients 1 and 3 had no signs of recurrence at the time of a follow-up examination. CONCLUSION.: Severe complications, mainly associated with the disturbance in healing of the retropharyngeal wall, were observed in all 3 patients. A preventive method, such as primary repair of the retropharyngeal wall using muscular/musculocutaneous flaps, should be considered for patients undergoing resection through a transoral approach after ion-beam irradiation. © 2010, Lippincott Williams & Wilkins.

Anterior cervical decompression and fusion (ACDF) is one of the standard surgical techniques for the treatment of cervical spinal disorders including degenerative diseases, trauma, infection, and tumor. However, the surgical outcomes of ACDF can be deteriorated by the development of adjacent segment degeneration or disease in the postoperative time course. In this article, the biomechanical background, incidence, risk factors, prevention, and management of this disorder are discussed. The incidence rate of adjacent segment degeneration or disease varies according to different reports. The risk factors are reported to be a level of fusion, the number of fusion levels, the preexistence of degenerative changes at the adjacent segments, and the alignment of the entire cervical spine and the fused segments. Although adjacent segment disease can be a sequel of the natural aging of the patients, a comparative study with control population revealed that patients who underwent ACDF had significantly higher incidence of disc degeneration at the adjacent segments than the control population. Adjacent segment diseases can be prevented by the use of motion preservation techniques including artificial disc replacement and decompression surgery without fusion. It can be managed by repeated ACDF, expansive laminoplasty, and artificial disc replacement, although the efficacies of these revision surgical procedures remain to be tested in the larger case series. © 2010 Lippincott Williams & Wilkins, Inc.

Osteoclastogenesis is a highly sophisticated process that involves a variety of membrane-bound proteins expressed in osteoblasts and osteoclast precursors. Over the past several years, proteolytic cleavage and release of the ectodomain of membrane-bound proteins, also referred to as ectodomain shedding, has emerged as an important posttranslational regulatory mechanism for modifying the function of cell surface proteins. In line with this notion, several membrane-bound molecules involved in osteoclastogenesis, including CSF-1R and receptor activator of NF-κB ligand (RANKL), are proteolytically cleaved and released from the cell surface. In this study, we investigated whether receptor activator of NF-κB (RANK), one of the most essential molecules in osteoclastogenesis, undergoes ectodomain shedding. The results showed that RANK is released in the form of a soluble monomeric protein and that TNF-α-converting enzyme is involved in this activity. We also identified potential cleavage sites in the juxtamembrane domain of RANK and found that rRANKL induces RANK shedding in a macrophage-like cell line RAW264.7 via TNFR-associated factor 6 and MAPK pathways. Furthermore, we found that RANKL-induced osteoclastogenesis is accelerated in TNF-α-converting enzyme-deficient osteoclast precursors. These observations suggest the potential involvement of ectodomain shedding in the regulation of RANK functions and may provide novel insights into the mechanisms of osteoclastogenesis. Copyright © 2010 by The American Association of Immunologists, Inc.

Development of bone morphogenetic protein (BMP) signaling modulators may provide useful therapeutic options for the treatment of large bony defects in clinical settings. Controversy remains over whether hepatocyte growth factor (HGF) is a positive or negative modulator of BMP-induced osteogenesis. This study analyzed osteogenic properties of HGF, particularly during BMP-2-induced bone formation. Using a mouse model of ectopic bone formation, HGF-impregnated gelatin sponges displayed significantly reduced bone formation induced by BMP-2, both radiologically and histologically. Abrogation of endogenous HGF production by knockdown of HGF mRNA resulted in upregulation of BMP-2-induced ALP activity for C2C12 myoblasts in vitro. In contrast, addition of exogenous HGF inhibited BMP-2-induced ALP activity and osteocalcin production by mouse embryonic fibroblasts (MEFs) through HGF-c-Met interactions. Inhibition of ALP activity by HGF was rescued by U0126, a MEK1/2 inhibitor, indicating that HGF suppresses the BMP-2-Smad axis via activation of ERK1/2. Importantly, treatment with HGF prior to administration of BMP-2 induced cellular proliferation of MEFs and did not influence subsequent osteoblast differentiation induced by BMP-2. The effects of HGF may differ according to the differentiation stage of mesenchymal stem cells, which would explain the inconsistencies seen in osteogenic properties of HGF in previous reports. The timing of HGF treatment is critical and should be carefully determined for successful induction of bone formation by BMPs. © 2009 Elsevier Ltd. All rights reserved.

Study Design. Prospective 10-year follow-up magnetic resonance imaging (MRI) study of patients who underwent anterior cervical decompression and fusion (ACDF) and healthy control subjects. Objective. To clarify the incidence of adjacent segment degeneration during 10 years after ACDF. Summary of Background Data. There have been few studies which investigated incidence of progression of degenerative changes at adjacent segments in patients treated by ACDF comparing with healthy subjects. Methods. Sixty-four patients who underwent ACDF (48 males, 16 females, mean age 47.3 years, mean follow-up 12.1 year) and 201 asymptomatic volunteers who underwent MRI in our previous study (113 males, 88 females, mean age; 41.1 year, mean follow-up; 11.7 years) were included in this study. The patients and control subjects underwent follow-up MRI in this study. Following MR findings were evaluated using a numerical grading system from C2-C3-C7-T1: (1) Decrease in signal intensity of disc (DSI), (2) Posterior disc protrusion (PDP), (3) Disc space narrowing, and (4) Foraminal stenosis. When an increase in at least one grade in any of the radiographic parameters was detected between the 2 time points, progression of disc degeneration was judged as present at the level of interest. Results. Progression of DSI was significantly more frequent in ACDF group than in control group at C4-C5, while progression of PDP was significantly more frequent in ACDF group than in control group at all levels except for C5-C6. Progression of disc space narrowing and foraminal stenosis was significantly more frequent in ACDF group at C3-C4 and at C6-C7, respectively. Conclusion. Although both ACDF patients and control subjects demonstrated progression of disc degeneration during 10 years, ACDF patients had significantly higher incidence of progression of disc degeneration at adjacent segments than control subjects, while progression of disc degeneration at adjacent segments was not always related to development of clinical symptoms. © 2009, Lippincott Williams & Wilkins.

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. © 2010 The Japanese Orthopaedic Association.

Object. In this paper, the authors' goal was to elucidate the clinical features and results of decompression surgery for extraforaminal stenosis at the lumbosacral junction. Methods. Twenty-eight patients with severe leg pain caused by extraforaminal stenosis at the lumbosacral junction (18 men and 10 women; mean age 68.2 ± 8.9 years) were treated by posterior decompression without fusion using a microendoscope in 19 patients and a surgical microscope or loupe in 9 patients. The decompression procedures consisted of partial resection of the sacral ala, the L-5 transverse process, and the L5-S1 facet joint along the L-5 spinal nerve. The following items were investigated: 1) preoperative neurological findings; 2) preoperative radiological findings, including plain radiographs, CT scans, selective radiculography of L-5; 3) surgical outcome as evaluated using the Japanese Orthopaedic Association scale for low-back pain (JOA score); and 4) need for revision surgery. Results. All patients presented with neurological deficits compatible with a diagnosis of L-5 radiculopathy such as weakness of the extensor hallucis longus muscle and sensory disturbance in the L-5 area together with neurogenic claudication. On plain radiographs, 21 patients (75%) and 17 patients (60.7%) exhibited lumbar scoliosis (? 5° ) and wedging of the L5-S1 intervertebral space (≥ 3 o ), respectively. The CT scans demonstrated marked osteophyte formation at the posterolateral margin of the L5-S1 vertebral bodies, and a selective L-5 nerve root block was effective in all patients. All patients reported pain relief immediately after surgery. The mean JOA scores were 11.3 ± 3.8 before surgery and 24.3 ± 3.4 at the time of the final follow-up examination; the recovery rate was 68.6 ± 16.5%. The mean estimated blood loss was 66.6 ± 98.6 ml, and the mean surgical time was 135.3 ± 46.5 minutes. No significant difference in the recovery rate of the JOA scores or in the surgical time and blood loss was observed between the 2 surgical approaches. Four patients underwent revision posterior interbody fusion for the recurrence of radicular pain as a result of intraforaminal stenosis in 3 patients and insufficient decompression of the extraforaminal area in the remaining patient at an average of 19.5 months after surgery. Conclusions. Extraforaminal stenosis at the lumbosacral junction is a rare but distinct pathological condition causing L-5 radiculopathy. Decompression surgery without fusion using a microendoscope or a surgical microscope/loupe is a feasible and less invasive surgical option for elderly patients with extraforaminal stenosis at the lumbosacral junction.

Study Design: A case report. OBJECTIVES.: To report a case of progressive yphoscoliosis associated with a tethered cord that was corrected by posterior vertebral column resection after complicated untethering surgery. Summary of Background Data: There have been few clinical reports on posterior vertebral column resection conducted for severe deformity associated with a tethered cord. Methods: A patient with progressive kyphoscoliosis associated with a tethered cord first underwent untethering surgery, resulting in neurologic deterioration. Posterior vertebral column resection was performed to correct the kyphoscoliosis while shortening the spinal column to prevent the spinal cord from stretch injury. Results: Good correction of kyphoscoliosis was obtained without further neurologic deterioration. The Cobb angles of scoliosis was 103° before surgery and 25° after surgery (correction rate; 75.7%), and that of kyphosis was 90° and 36°, respectively (correction rate; 60.0%). Conclusion: Correction of progressive kyphoscoliosis associated with a tethered cord can be achieved successfully by posterior vertebral column resection even after complicated untethering surgery. © 2009, Lippincott Williams & Wilkins.

Receptor activator of nuclear factor-κB ligand (RANKL) and osteoprotegerin (OPG), a decoy receptor of RANKL, maintain bone mass by regulating the differentiation of osteoclasts, which are bone-resorbing cells. Endochondral bone ossification and bone fracture healing involve cartilage resorption, a less well-understood process that is needed for replacement of cartilage by bone. Here we describe the role of OPG produced by chondrocytes in chondroclastogenesis. Fracture healing in OPG-/- mice showed faster union of the fractured bone, faster resorption of the cartilaginous callus, and an increased number of chondroclasts at the chondroosseous junctions compared with that in wild-type littermates. When a cultured pellet of OPG-/- chondrocytes was transplanted beneath the kidney capsule, the pellet recruited many chondroclasts. The pellet showed the ability to induce tartrate-resistant acid phosphatase-positive multinucleated cells from RAW 264.7 cells in vitro. Finally, OPG-/- chondrocytes (but not wild-type chondrocytes) cultured with spleen cells induced many tartrate-resistant acid phosphatase-positive multinucleated cells. The expression of RANKL and OPG in chondrocytes was regulated by several osteotropic factors including 1,25-dihydroxyvitamin D3, PTHrP, IL-1α, and TNF-α. Thus, local OPG produced by chondrocytes probably controls cartilage resorption as a negative regulator for chondrocyte-dependent chondroclastogenesis. Copyright © 2009 by The Endocrine Society.

There have been few studies that investigated and clarified the relationships between progression of degenerative changes and sagittal alignment of the cervical spine. The objective of the study was to longitudinally evaluate the relationships among progression of degenerative changes of the cervical spine with age, the development of clinical symptoms and sagittal alignment of the cervical spine in healthy subjects. Out of 497 symptom-free volunteers who underwent MRI and plain radiography of the cervical spine between 1994 and 1996, 113 subjects (45 males and 68 females) who responded to our contacts were enrolled. All subjects underwent another MRI at an average of 11.3 years after the initial study. Their mean age at the time of the initial imaging was 36.6 ± 14.5 years (11-65 years). The items evaluated on MRI were (1) decrease in signal intensity of the intervertebral disks, (2) posterior disk protrusion, and (3) disk space narrowing. Each item was evaluated using a numerical grading system. The subjects were divided into four groups according to the age and sagittal alignment of the cervical spine, i.e., subjects under or over the age of 40 years, and subjects with the lordosis or non-lordosis type of sagittal alignment of the cervical spine. During the 10-year period, progression of decrease in signal intensity of the disk, posterior disk protrusion, and disk space narrowing were recognized in 64.6, 65.5, and 28.3% of the subjects, respectively. Progression of posterior disk protrusion was significantly more frequent in subjects over 40 years of age with non-lordosis type of sagittal alignment. Logistic regression analysis revealed that stiff shoulder was closely correlated with females (P = 0.001), and that numbness of the upper extremity was closely correlated with age (P = 0.030) and male (P = 0.038). However, no significant correlation between the sagittal alignment of the cervical spine and clinical symptoms was detected. Sagittal alignment of the cervical spine had some impact on the progression of degenerative changes of the cervical spine with aging; however, it had no correlation with the occurrence of future clinical symptoms. © 2009 Springer-Verlag.

Study Design. Retrospective case series. Objective. To evaluate our treatment strategy for myxopapillary ependymomas of the cauda equina. Summary of Background Data. Some patients with myxopapillary ependymoma develop cerebrospinal fluid (CSF) dissemination leading to poor prognosis. Because of the rarity of this tumor, there is no consensus on its optimal treatment options and prognosis. Methods We reviewed 25 cases of myxopapillary ependymomas, treated surgically between 1972 and 2005. The mean postoperative follow-up period was 10.4 years. The effects of surgical margins at surgery and postoperative radiotherapy on tumor recurrence and prognosis were investigated. Results In 15 patients, total resection achieved (6 cases of en bloc resection without postoperative radiation, and in 9 cases piecemeal resection) was followed by whole brain and spinal cord radiation or local irradiation. Fourteen of these patients survived without tumor recurrence. In 1 case of total resection without radiotherapy, the tumor capsule was violated intraoperatively and local recurrence occurred 2 years after surgery. In 4 patients, the tumors were removed subtotally. Of these, 2 patients who received radiation (24 Gy) only to the whole brain and spinal cord developed recurrence, and 2 who received whole brain and spinal cord radiation (24 Gy) supplemented with local radiation (46 Gy) developed no recurrence. The remaining 6 patients received partial resection after local radiation (40-50 Gy) alone, and all 6 died of CSF dissemination. Conclusion. The results of the present study indicate that the surgical margin obtained at the initial surgery and the extent and amount of postoperative radiation can be crucial factors determining the prognosis of patients with myxopapillary ependymoma. Although this tumor is histologically benign, CSF dissemination can occur once tumor capsule is violated, before or during surgery. Therefore, early diagnosis is essential, and a therapeutic strategy including radiotherapy, on the assumption that this tumor is malignant, should be established. © 2009, Lippincott Williams & Wilkins.