Keijiro Mukaiyama

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.

The skeletal muscle cross sectional area in long-term bisphosphonate users is smaller than that of bone mineral density-matched controls with increased serum pentosidine concentrations

Bisphosphonates are effective in increasing bone mineral density (BMD), but fragility fractures can still occur despite bisphosphonate treatment. The purpose of this study was to determine if long-term bisphosphonate users have characteristic findings in the musculoskeletal system, which could put them at risk of developing typical or atypical femoral fractures. We recruited 40 female patients who had taken bisphosphonates for more than 3 years. The control group included 60 volunteers who were matched by age, body mass index, and dual-energy X-ray absorptiometry-derived BMDs. We measured the skeletal muscle cross sectional area around the proximal thigh and buckling ratio of the femoral neck using quantitative computed tomography (qCT) and several biochemical markers of bone metabolism. Those parameters were compared between the groups. While no significant differences of buckling ratio derived from qCT were detected, the skeletal muscle cross sectional area was significantly smaller in the long-term bisphosphonate users than in the controls. Furthermore, the serum pentosidine level was significantly higher in the bisphosphonate users than in the controls. To determine if those differences were attributable to bisphosphonate treatment, we further compared those parameters between before and after 3 years of bisphosphonate treatment in 32 patients. After 3 years of bisphosphonate treatment, the BMD of the femoral neck and serum pentosidine level increased but not the skeletal muscle cross sectional area. In the present study, the skeletal muscle mass did not match the bone mass in long-term bisphosphonate users, thus suggesting that increases in BMD by bisphosphonates are unlikely to have secondary positive effects on the surrounding skeletal muscles. Also, serum pentosidine levels were greater in the long-term bisphosphonate users. Further study is necessary to test if such patients are prone to develop typical or atypical femoral fractures.

a case series of pregnancy- and lactation- associated osteoporosis and a review of the literature

The syndrome of pregnancy- and lactation-associated osteoporosis is a rare disorder whose precise etiology and treatment are largely unknown. We herein report two such cases occurring in the early postpartum period that led to multiple fragility compression fractures. Combination therapy of vitamin D and vitamin K enabled a marked gradual increase in bone mineral density.

The Pathophysiology of Primary Hip Osteoarthritis may Originate from Bone Alterations

Objectives: The aim of this study was to investigate whether bone alterations detected by hip magnetic resonance imaging (MRI) were associated with subsequent primary hip OA. Methods: We enrolled 7 patients with hip joint pain from their first visit, at which hip joints were classified as grade 0 or I on the Kellgren-Lawrence grading scale. Plain radiographs and magnetic resonance imaging (MRI) were performed on all cases, and pain was assessed with the Denis pain scale. Average age, height, weight, body mass index, bone mineral density (L1-4), central edge angle, Sharp’s angle, and acetabular hip index were calculated. Results: Within two months of the onset of pain, 4 of the 7 cases showed broad bone signal changes, while 3 cases showed local signal changes in the proximal femur on hip MRI. Three to 6 months after the onset of pain, in all patients whose pain was much improved, plain radiographs showed progression to further-stage OA. Conclusion: Our findings suggest that bone abnormalities in the proximal femur might be involved in the pathogenesis of primary hip OA.

Pedicle morphology using computed tomography-based navigation system in adolescent idiopathic scoliosis.

Study Design/Setting: Retrospective study. Objective: The purpose of this study was to use multidimensional analysis with a computed tomography (CT)-based navigation system to measure the outer cortical diameter and the maximum screw trajectory length of the pedicle of the thoracic and lumbar regions of the spine in adolescent idiopathic scoliosis (AIS) patients. Another objective was to identify pedicles that require cautious insertion of screws. Summary of Background Data: Pedicle diameter in AIS patients was narrower on the concave side of the scoliotic curve. Many researchers have measured pedicle diameter and length of AIS patients by using standard CT or magnetic resonance imaging (MRI), but only few have used 3-dimensional imaging, especially CT-based navigation. Methods: Fifteen patients with right-side thoracic AIS who underwent pedicle screw fixation were studied. A CT-based navigation system was used to measure the pedicle diameter, defined as the widest outer cortical diameter at the narrowest part of the pedicle. Moreover, the maximum pedicle screw trajectory length was measured as the distance between the posterior cortical entry point of the pedicle screw and the anterior vertebral cortex in line with the axis of the pedicle between T1 and L5. In addition, the values of each parameter taken using the CT navigation system and the standard axial CT were compared. Results: Pedicles on the concave side of the main thoracic curve apex and proximal thoracic curve tended to have the narrowest diameters. The mean length of the longest screw that could be fixed was longer on the right side, except for T8 and T9. Our data showed screw size feasibility as follows: 25 or 30 mm screws were feasible from T1 to T5; 30 or 35 mm screws, from T6 to T12; and 35 or 40 mm screws, from L1 to L5. Pedicle diameter measured by the CT navigation system was larger than that measured by standard axial CT. Left-side pedicle length measured by the CT navigation system was lesser than that measured by standard axial CT. Conclusions: Pedicle diameter in patients with AIS is narrower on the concave side of the scoliotic curve, and therefore, caution should be exercised during screw insertion on the concave side.

Role of Weekly Teriparatide Administration in Osseous Union Enhancement within Six Months After Posterior or Transforaminal Lumbar Interbody Fusion for Osteoporosis-Associated Lumbar Degenerative Disorders: A Multicenter, Prospective Randomized Study.

Background: For elderly patients, posterior lumbar interbody fusion (PLIF) or transforaminal lumbar interbody fusion (TLIF) is usually performed to treat lumbar degenerative diseases. However, some patients exhibit pseudarthrosis following such procedures. The anabolic agent teriparatide is an approved treatment for promoting bone formation in osteoporotic patients. Our multicenter, prospective randomized study assessed the role of once-weekly teriparatide administration on patient outcomes following interbody fusion. Methods: Patients were females who were ≥50 years of age, had a bone mineral density (BMD) of <80% of the sex-matched young adult mean and/or previous spinal compression or femoral fractures, and had lumbar degenerative disease. Patients were randomly allocated to receive either weekly teriparatide, administered subcutaneously starting at week 1, for 6 months postoperatively (the teriparatide arm), or no teriparatide (the control arm). Blinded radiographic evaluations were performed using dynamic radiography and computed tomography (CT) and assessed by modified intention-to-treat analysis and per-protocol analysis. Clinical and neurological symptoms were evaluated using the Japanese Orthopaedic Association Back Pain Evaluation Questionnaire (JOA-BPEQ) and the Oswestry Disability Index (ODI). Results: Seventy-five patients were randomized to treatment, and 66 patients completed treatment. At 4 months postoperatively, bone fusion in the 2 center CT slices was significantly higher in the teriparatide arm compared with the control arm in the age-adjusted modified intention-to-treat analysis and was significantly higher at 6 months in the per-protocol analysis. Radiographic examinations showed no disc-space narrowing and no intervertebral disc instability. JOA-BPEQ and ODI results were improved postoperatively in both treatment arms. Conclusions: Weekly administration of teriparatide promoted bone formation at the surgical fusion site and decreased bone resorption, as indicated by bone metabolic marker results, within the early postoperative period. Our findings suggest that combining lumbar interbody fusion and teriparatide treatment may be an effective option for managing lumbar degenerative disease in elderly patients. Level of Evidence: Therapeutic Level I. See Instructions for Authors for a complete description of levels of evidence.

Comparison of Clinical and Radiological Results of Posterolateral Fusion and Posterior Lumbar Interbody Fusion in the Treatment of L4 Degenerative Lumbar Spondylolisthesis

Study Design Multicenter analysis of two groups of patients surgically treated for degenerative L4 unstable spondylolisthesis. Purpose To compare the clinical and radiographic outcomes of posterolateral fusion (PLF) and posterior lumbar interbody fusion (PLIF) for degenerative L4 unstable spondylolisthesis. Overview of Literature Surgery for lumbar degenerative spondylolisthesis is widely performed. However, few reports have compared the outcome of PLF to that of PLIF for degenerative L4 unstable spondylolisthesis. Methods Patients with L4 unstable spondylolisthesis with Meyerding grade II or more, slip of >10° or >4 mm upon maximum flexion and extension bending, and posterior opening of >5 degree upon flexion bending were studied. Patients were treated from January 2008 to January 2010. Patients who underwent PLF (n=12) and PLIF (n=19) were followed-up for >2 years. Radiographic findings and clinical outcomes evaluated by the Japanese Orthopaedic Association (JOA) score were compared between the two groups. Radiographic evaluation included slip angle, translation, slip angle and translation during maximum flexion and extension bending, intervertebral disc height, lumbar lordotic angle, and fusion rate. Results JOA scores of the PLF group before surgery and at final follow-up were 12.3±4.8 and 24.1±3.7, respectively; those of the PLIF group were 14.7±4.8 and 24.2±7.8, respectively, with no significant difference between the two groups. Correction of slip estimated from postoperative slip angle, translation, and maintenance of intervertebral disc height in the PLIF group was significantly (p<0.05) better than those in the PLF group. However, there was no significant difference in lumbar lordotic angle, slip angle and translation angle upon maximum flexion, or extension bending. Fusion rates of the PLIF and PLF groups had no significant difference. Conclusions The L4–L5 level posterior instrumented fusion for unstable spondylolisthesis using both PLF and PLIF could ameliorate clinical symptoms when local stability is achieved.

Eldecalcitol, in Combination with Bisphosphonate, Is Effective for Treatment of Japanese Osteoporotic Patients.

Alfacalcidol (ALF) and eldecalcitol (ELD) are vitamin D analogues that can be combined with anti-resorption drugs, such as bisphosphonate (BP) for the treatment of osteoporosis (OP). There has been no report comparing the effects of those vitamin D analogs in combination with BPs. Twenty female patients with OP were enrolled, and all of them were treated with ALF and BPs. After switching from ALF to ELD, we examined the effectiveness of ALF and ELD. The averaged age was 69.4 years and the period of BP usage was between 1 to 13.4 years (mean period was 3.7 years). Serum corrected calcium, serum inorganic phosphorus, serum bone specific alkaline phosphatase (BAP), and serum tartrate-resistant acid phosphatase (TRACP)-5b were measured prior to ELD and at 6 months afterwards. Bone mineral density (BMD) of the lumbar spine (L-BMD), femoral neck, and total hip BMD were assessed one year before, prior to, and one year after ELD therapy commencement. Six months after switching from ALF to ELD, BAP and TRACP-5b values significantly decreased. After one year of ALF therapy, L-BMD, total hip BMD and femoral neck H-BMD values slightly increased. In contrast, a year following the change from ALF to ELD, L-BMD significantly increased and femoral neck BMD slightly increased, but total hip BMD did not. These results suggest that the treatment with ELD after ALF significantly suppressed bone turnover and increased L-BMD. Thus, the combined therapy with ELD is more effective for OP treatment than that with ALF.

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.

Complications Associated With Spine Surgery in Patients Aged 80 Years or Older: Japan Association of Spine Surgeons with Ambition (JASA) Multicenter Study:

Study Design: Retrospective study of registry data. Objectives: Aging of society and recent advances in surgical techniques and general anesthesia have increased the demand for spinal surgery in elderly patients. Many complications have been described in elderly patients, but a multicenter study of perioperative complications in spinal surgery in patients aged 80 years or older has not been reported. Therefore, the goal of the study was to analyze complications associated with spine surgery in patients aged 80 years or older with cervical, thoracic, or lumbar lesions. Methods: A multicenter study was performed in patients aged 80 years or older who underwent 262 spinal surgeries at 35 facilities. The frequency and severity of complications were examined for perioperative complications, including intraoperative and postoperative complications, and for major postoperative complications that were potentially life threatening, required reoperation in the perioperative period, or left a permanent injury. Results: Perioperative complications occurred in 75 of the 262 surgeries (29%) and 33 were major complications (13%). In multivariate logistic regression, age over 85 years (hazard ratio [HR] = 1.007, P = 0.025) and estimated blood loss ≥500 g (HR = 3.076, P = .004) were significantly associated with perioperative complications, and an operative time ≥180 min (HR = 2.78, P = .007) was significantly associated with major complications. Conclusions: Elderly patients aged 80 years or older with comorbidities are at higher risk for complications. Increased surgical invasion, and particularly a long operative time, can cause serious complications that may be life threatening. Therefore, careful decisions are required with regard to the surgical indication and procedure in elderly patients.