Masashi Uehara

Computer-assisted C1-C2 Transarticular Screw Fixation "Magerl Technique" for Atlantoaxial Instability

Study Design A retrospective study. Purpose To evaluate the surgical results of computer-assisted C1-C2 transarticular screw fixation for atlantoaxial instability and the usefulness of the navigation system. Overview of Literature We used a computed tomography (CT)-based computer navigation system in planning and screw insertion in Magerls procedure, which provides the most rigid atlantoaxial fusion, to avoid risk of vertebral artery (VA) tear by avoiding high-riding VA during screw insertion. Methods Twenty patients who underwent atlantoaxial fusion under the CT-based navigation system were studied. The mean observation period was 33.5 months. The evaluated items included the existence of VA stenosis by preoperative magnetic resonance angiography, surgical time, blood loss volume, Japanese Orthopaedic Association (JOA) score and Ranawats pain criteria before surgery and at final follow-up, postoperative screw position evaluated by CT, and bony fusion. Results The mean operation time was 205 minutes, with the mean blood loss volume of 242 ml. The mean JOA score was 11.6 points before surgery and 13.7 at final follow-up. Occipital and/or cervical pain presented before operation was remitted or resolved in all patients. Evaluation of screw insertion by CT revealed correct penetration to atlantoaxial joints, with a perforation rate of 2.6%. There was no complication, including VA tear, and all patients who were followed-up during one year or more after surgery achieved bony fusion. Some subjects who appeared inappropriate for surgery from CT images were assessed as eligible for surgery based on the evaluation results obtained using the navigation system. Conclusions It was demonstrated that the CT-based navigation system is an effective support device for Magerls procedure.

Hodgkin's disease of the thoracic vertebrae

BACKGROUND CONTEXT Hodgkins disease rarely occurs in the spine, which is usually a setting for the advanced form of the disease. PURPOSE To describe an unusual case of isolated, primary spinal Hodgkins disease and to draw attention to this disease as a possible diagnosis in patients with mixed inflammatory cell infiltrate lesions located in the thoracic spine. STUDY DESIGN/SETTING A case report of a 28-year-old woman who presented with back pain and progressive weakness in the lower extremities as a result of spinal cord compression from Hodgkins disease of the thoracic vertebrae. METHODS We report a new case of spinal cord compression resulting from Hodgkins disease of the thoracic vertebrae. Decompression surgery was performed in the patient, followed by antibiotic treatment. RESULTS Antibiotic therapy temporarily improved inflammation and fever. However, magnetic resonance imaging (MRI) evaluation showed that the inflammatory reaction in the lesion was not completely resolved. The disease progressed and later investigations revealed Hodgkins disease, which improved with a course of chemotherapy and radiation. CONCLUSIONS Hodgkins disease should be considered in the differential diagnosis of spinal neoplastic lesions with clinical features similar to spondylitis. Because MRI evaluation showed that the vertebral disc was maintained in this case, the presence of a tumor rather than inflammation should have been suspected.

Cervical Pedicle Screw Fixation Combined with Laminoplasty for Cervical Spondylotic Myelopathy with Instability

Study Design A retrospective study. Purpose To evaluate the surgical results of cervical pedicle screw (CPS) fixation combined with laminoplasty for treating cervical spondylotic myelopathy (CSM) with instability. Overview of Literature Cervical fixation and spinal cord decompression are required for CSM patients with instability. However, only a few studies have reported on CPS fixation combined with posterior decompression for unstable CSM patients. Methods Thirteen patients that underwent CPS fixation combined with laminoplasty for CSM with instability were evaluated in this study. We assessed the clinical and radiological results of the surgical procedures. The Japanese Orthopedic Association (JOA) scoring system was used to evaluate the clinical results. The percentages of sli p, difference in sli p angle between maximum flexion and maximum extension of unstable intervertebrae, and perforation rate of CPS were evaluated. Results The mean JOA scores before surgery, immediately after surgery, and at final follow-up were 9.1, 13.3, and 12.6, respectively. The mean percentages of sli p before surgery, immediately after surgery, and at final follow-up were 9.1%, 3.2%, and 3.5%, respectively; there were significant improvements immediately after surgery and at final follow-up. The difference in sli p angle between the maximum flexion and maximum extension of the unstable intervertebrae changed from 9.0° before surgery to 1.6° at the final follow-up. The perforation rate of CPS was 10.9%. Conclusions The results suggest that CPS fixation combined with laminoplasty is an effective surgical procedure for treating CSM with instability.

Preoperative Spinal Cord Damage Affects the Characteristics and Prognosis of Segmental Motor Paralysis After Cervical Decompression Surgery

Study Design. Retrospective analysis. Objective. To test the hypothesis that preoperative spinal cord damage affects postoperative segmental motor paralysis (SMP). Summary of Background Data. SMP is an enigmatic complication after cervical decompression surgery. The cause of this complication remains controversial. We particularly focused on preoperative T2-weighted high signal change (T2HSC) on magnetic resonance imaging in the spinal cord, and assessed the influence of preoperative T2HSC on SMP after cervical decompression surgery. Methods. A retrospective review of 181 consecutive patients (130 males and 51 females) who underwent cervical decompression surgery was conducted. SMP was defined as development of postoperative motor palsy of the upper extremities by at least 1 grade in manual muscle testing without impairment of the lower extremities. The relationship between the locations of T2HSC in preoperative magnetic resonance imaging and SMP and Japanese Orthopedic Association score was investigated. Results. Preoperative T2HSC was detected in 78% (142/181) of the patients. SMP occurred in 9% (17/181) of the patients. Preoperative T2HSC was not a significant risk factor for the occurrence of SMP (P = 0.682). However, T2HSC significantly influenced the severity of SMP: the number of paralyzed segments increased with an incidence rate ratio of 2.2 (P = 0.026), the manual muscle score deteriorated with an odds ratio of 8.4 (P = 0.032), and the recovery period was extended with a hazard ratio of 4.0 (P = 0.035). In patients with preoperative T2HSC, Japanese Orthopaedic Association scores remained lower than those in patients without T2HSC throughout the entire period including pre- and postoperative periods (P < 0.001). Conclusion. Preoperative T2HSC was associated with worse severity of SMP in patients who underwent cervical decompression surgery, suggesting that preoperative spinal cord damage is one of the pathomechanisms of SMP after cervical decompression surgery. Level of Evidence: 3

Efficacy of Denosumab for Osteoporosis in Three Female Patients with Osteogenesis Imperfecta.

Osteogenesis imperfecta (OI) is an inherited bone disorder that causes fractures due to impaired production of collagen type I. In recent years, denosumab, a human monoclonal antibody against receptor activator of nuclear factor κB ligand (RANKL), has become widely used as an anti-osteoclastic agent for osteoporosis. This study investigated osteoporotic cases of OI to examine effects of denosumab on bone fragility. This was a retrospective, consecutive case series that included 3 female patients aged 42, 40, and 14 years, respectively. One patient carries a point mutation (c.G769A) in the COL1A1 gene, encoding collagen type I alpha 1 chain, which causes an amino-acid substitution (p.G257R). By contrast, no mutation was found in the analyzed regions of the OI responsive genes in another two patients (mother and daughter). These three patients underwent subcutaneous injection of denosumab every 6 months. All patients underwent dual-energy X-ray absorptiometry for bone mineral density (BMD) measurement of the lumbar 1-4 spine (L-BMD) and bilateral hips (H-BMD) before and during treatment. BMD and laboratory data were evaluated before, between 2 and 4 months, and at 6, 12, 18, and 24 months of therapy. No fractures or severe side effects, such as hypocalcemia, were observed during denosumab treatment. Both L-BMD and H-BMD were increased by denosumab. At 24 months, the mean percentage changes in L-BMD and H-BMD were 14.7% and 15.1%, respectively. In conclusion, no bone fragility fractures occurred during 2 years of denosumab administration in OI patients. Denosumab therefore is a good therapeutic option in the OI patients.

Pedicle Screw Loosening after Posterior Spinal Fusion for Adolescent Idiopathic Scoliosis in Upper and Lower Instrumented Vertebrae Having Major Perforation

Study Design. A retrospective chart review. Objective. The aim of this study was to investigate the incidence and characteristics of screw loosening in surgically treated adolescent idiopathic scoliosis (AIS) patients. Summary of Background Data. Pedicle screws are widely used in posterior spinal fusion for AIS, although postoperative loosening can occur. However, few reports exist on screw loosening after pedicle screw fixation in young scoliosis patients and the etiology of loosening is not well known. Methods. One hundred twenty AIS patients (9 males, 111 females; mean age: 15.0 years) who had received pedicle screw fixation were retrospectively reviewed. All patients underwent routine computed tomography (CT) reconstruction scans at 6 months postoperatively to assess screw position, bony fusion, and the presence of screw loosening. The perforation status of each pedicle screw was assigned a grade of 0 to 3 using Rao classification. Results. Forty-three of 1624 (2.6%) screws showed evidence of loosening on CT. Screw loosening rates according to vertebral insertion level were upper instrumented vertebra (UIV): 9.6%; lower instrumented vertebra (LIV): 5.4%; one vertebra below the UIV: 1.8%; one vertebra above the LIV: 0.5%; two vertebrae below the UIV: 1.2%; and three vertebrae below the UIV: 0.9%. Screw loosening rates based on screw perforation grade were Grade 0: 1.4%; Grade 1: 3.1%; Grade 2: 15.5%; and Grade 3: 15.2%. Multivariate analysis revealed a distance from the UIV or LIV of one vertebra as well as the presence of major perforation to be independent factors affecting screw loosening. The odds ratios (ORs) of UIV/LIV insertion and major perforation were 73.4 and 17.2, respectively. When major perforations occurred in the UIV or LIV, the OR for loosening approached 1262. Conclusion. Pedicle screw loosening after posterior spinal fusion in AIS patients tend to occur in the UIV or LIV. Major screw perforation is also significantly associated with screw loosening. The risk of loosening becomes compounded when major perforations are present in the UIV or LIV. Level of Evidence: 4

Osteoid osteoma presenting as thoracic scoliosis.

BACKGROUND CONTEXT Osteoid osteoma of the thoracic spine is relatively uncommon and is often difficult to diagnose, especially when patients do not complain of pain. PURPOSE This study aims to describe an unusual case of scoliosis caused by osteoid osteoma of the thoracic spine that was challenging to diagnose. STUDY DESIGN/SETTING A case report of a 12-year-old girl who presented with scoliosis caused by osteoid osteoma of the thoracic spine without apparent pain was carried out. METHODS Diagnosis of the lesion was made using computed tomography (CT) and magnetic resonance imaging as well as the Scoliosis Research Society-22 (SRS-22) patient-based questionnaire. RESULTS A preoperative CT myelogram revealed a mass lesion in the lamina of the 10th thoracic vertebra that was considered to be osteoid osteoma. This diagnosis was histologically confirmed following tumor excision. The patients spinal deformity and SRS-22 scores were both improved at 5 months postoperatively. CONCLUSIONS Osteoid osteoma of the thoracic spine may present as non-painful scoliosis. Tumor resection is effective. Clinicians should bear this uncommon lesion in mind during recommended CT examination before scoliosis surgery.

Comparison of Spinous Process-Splitting Laminectomy versus Conventional Laminectomy for Lumbar Spinal Stenosis

Study Design Seventy-five patients who had been treated for lumbar spinal stenosis (LSS) were reviewed retrospectively. Purpose Invasion into the paravertebral muscle can cause major problems after laminectomy for LSS. To address these problems, we performed spinous process-splitting laminectomy. We present a comparative study of decompression of LSS using 2 approaches. Overview of Literature There are no other study has investigated the lumbar spinal instability after spinous process-splitting laminectomy. Methods This study included 75 patients who underwent laminectomy for the treatment of LSS and who were observed through follow-ups for more than 2 years. Fifty-five patients underwent spinous process-splitting laminectomy (splitting group) and 20 patients underwent conventional laminectomy (conventional group). We evaluated the clinical and radiographic results of each surgical procedure. Results Japanese Orthopaedic Association score improved significantly in both groups two years postoperatively. The following values were all significantly lower, as shown with p-values, in the splitting group compared to the conventional group: average operating time (p=0.002), postoperative C-reactive protein level (p=0.006), the mean postoperative number of days until returning to normal body temperature (p=0.047), and the mean change in angulation 2 years postoperatively (p=0.007). The adjacent segment degeneration occurred in 6 patients (10.9%) in the splitting group and 11 patients (55.0%) in the conventional group. Conclusions In this study, the spinous process-splitting laminectomy was shown to be less invasive and more stable for patients with LSS, compared to the conventional laminectomy.

Mid-Term Results of Computer-Assisted Cervical Pedicle Screw Fixation

Study Design A retrospective study. Purpose The present study aimed to evaluate mid-term results of cervical pedicle screw (CPS) fixation for cervical instability. Overview of Literature CPS fixation has widely used in the treatment of cervical spinal instability from various causes; however, there are few reports on mid-term surgical results of CPS fixation. Methods Record of 19 patients who underwent cervical and/or upper thoracic (C2-T1) pedicle screw fixation for cervical instability was reviewed. The mean observation period was 90.2 months. Evaluated items included Japanese Orthopaedic Association (JOA) score and C2-7 lordotic angle before surgery and at 5 years after surgery. Postoperative computerized tomography was used to determine the accuracy of screw placement. Visual analog scale (VAS) for neck pain and radiological evidence of adjacent segment degeneration (ASD) at the 5-year follow-up were also evaluated. Results Mean JOA score was significantly improved from 9.0 points before surgery to 12.8 at 5 years after surgery (p=0.001). The C2-7 lordotic angle of the neutral position improved from 6.4° to 7.8° at 5 years after surgery, but this was not significant. The major perforation rate was 5.0%. There were no clinically significant complications such as vertebral artery injury, spinal cord injury, or nerve root injury caused by any screw perforation. Mean VAS for neck pain was 49.4 at 5 years after surgery. The rate of ASD was 21.1%. Conclusions Our mid-term results showed that CPS fixation was useful for treating cervical instability. Severe complications were prevented with the assistance of a computed tomography-based navigation system.

Spinal cord MRI signal changes at 1 year after cervical decompression surgery is useful for predicting midterm clinical outcome: an observational study using propensity scores

BACKGROUND CONTEXT There is little information on the relationship between magnetic resonance imaging (MRI) T2-weighted high signal change (T2HSC) in the spinal cord and surgical outcome for cervical myelopathy. We therefore examined whether T2HSC regression at 1 year postoperatively reflected a 5-year prognosis after adjustment using propensity scores for potential confounding variables, which have been a disadvantage of earlier observational studies. PURPOSE The objective of this study was to clarify the usefulness of MRI signal changes for the prediction of midterm surgical outcome in patients with cervical myelopathy. STUDY DESIGN/SETTING This is a retrospective cohort study. PATIENT SAMPLE We recruited 137 patients with cervical myelopathy who had undergone surgery between 2007 and 2012 at a median age of 69 years (range: 39-87 years). OUTCOME MEASURES The outcome measures were the recovery rates of the Japanese Orthopaedic Association (JOA) scores and the visual analog scale (VAS) scores for complaints at several body regions. MATERIALS AND METHODS The subjects were divided according to the spinal MRI results at 1 year post surgery into the MRI regression group (Reg+ group, 37 cases) with fading of T2HSC, or the non-regression group (Reg- group, 100 cases) with either no change or an enlargement of T2HSC. The recovery rates of JOA scores from 1 to 5 years postoperatively along with the 5-year postoperative VAS scores were compared between the groups using t test. Outcome scores were adjusted for age, sex, diagnosis, symptom duration, and preoperative JOA score by the inverse probability weighting method using propensity scores. RESULTS The mean recovery rates in the Reg- group were 35.1%, 34.6%, 27.6%, 28.0%, and 30.1% from 1 to 5 years post surgery, respectively, whereas those in the Reg+ group were 52.0%, 52.0%, 51.1%, 49.0%, and 50.1%, respectively. The recovery rates in the Reg+ group were significantly higher at all observation points. At 5 years postoperatively, the VAS score for pain or numbnessin the arms or hands of the patients in the Reg+ group (24.7 mm) was significantly milder than that of the patients in the Reg- group (42.2 mm). CONCLUSIONS Spinal T2HSC improvement at 1 year postoperatively may predict a favorable recovery until up to 5 years after surgery.