Kengo Yamamoto

Surgical results and related factors for ossification of posterior longitudinal ligament of the thoracic spine: A multi-institutional retrospective study

Study Design. Retrospective multi-institutional study Objective. To describe the surgical outcomes in patients with ossification of the posterior longitudinal ligament in the thoracic spine (T-OPLL) and to clarify factors related to the surgical outcomes. Summary of Background Data. Detailed analyses of surgical outcomes of T-OPLL have been difficult because of the rarity of this disease. Methods. The subjects were 154 patients with T-OPLL who were surgically treated at 34 institutions between 1998 and 2002. The surgical procedures were laminectomy in 36, laminoplasty in 51, anterior decompression via anterior approach in 25 and via posterior approach in 29, combined anterior and posterior fusion in 8, and sternum splitting approach in 5 patients. Instrumentation was conducted in 52 patients. Assessments were made on (1) The Japanese Orthopedic Association (JOA) scores (full score, 11 points), its recovery rates, (2) factors related to surgical results, and (3) complications and their consequences. Results. (1) The mean JOA score before surgery was 4.6 ± 2.0 and, 7.1 ± 2.5 after surgery. The mean recovery rate was 36.8% ± 47.4%. (2) The recovery rate was 50% or higher in 72 patients (46.8%). Factors significantly related to this were location of the maximum ossification (T1–T4) (odds ratio, 2.43–4.17) and the use of instrumentation (odds ratio, 3.37). (3) The frequent complications were deterioration of myelopathy immediately after surgery in 18 (11.7%) and dural injury in 34 (22.1%) patients. Conclusion. The factors significantly associated with favorable surgical results were maximum ossification located at the upper thoracic spine and use of instrumentation. T-OPLL at the nonkyphotic upper thoracic spine can be treated by laminoplasty that is relatively a safe surgical procedure for neural elements. The use of instrumentation allows correction of kyphosis or prevention of progression of kyphosis, thereby, enhancing and maintaining decompression effect, and its use should be considered with posterior decompression.

Radiographic predictors for the development of myelopathy in patients with ossification of the posterior longitudinal ligament: a multicenter cohort study.

Study Design. A multicenter cohort study was performed retrospectively. Objective. To identify radiographic predictors for the development of myelopathy in patients with ossification of the posterior longitudinal ligaments (OPLL). Summary of Background Data. The pathomechanism of myelopathy in the OPLL remains unknown. Some patients with large OPLL have not exhibited myelopathy for a long periods of time. Predicting the course of future neurologic deterioration in asyptomatic patients with OPLL is difficult at their initial visit. Methods. A total of 156 OPLL patients from 16 spine institutes with an average of 10.3 years of follow-up were reviewed. Subjects underwent a plain roentgenogram, computed tomography (CT), and magnetic resonance imaging of the cervical spine during the follow-up. The trauma history of the cervical spine, maximum percentage of spinal canal stenosis in a plain roentgenogram and CT, range of motion of the cervical spine, and axial ossified pattern in magnetic resonance imaging or CT were reviewed in relation to the existence of myelopathy. Results. All 39 patients with greater than 60% spinal canal stenosis on the plain roentgenogram exhibited myelopathy. Of 117 patients with less than 60% spinal canal stenosis, 57 (49%) patients exhibited myelopathy. The range of motion of the cervical spine was significantly larger in patients with myelopathy than in those of without it. The axial ossified pattern could be classified into 2 types: a central type and a lateral deviated type. The incidence of myelopathy in patients with less than 60% spinal canal stenosis was significantly higher in the lateral deviated-type group than in the central-type group. Fifteen patients of 156 subjects developed trauma-induced myelopathy. Of the 15 patients, 13 had mixed-type OPLL and 2 had segmental-type OPLL. Conclusion. Static and dynamic factors were related to the development of myelopathy in OPLL.

Effects of A-P translation and rotation on the wear of UHMWPE in a total knee joint simulator

We developed a three-channel total knee joint simulator and studied the effect of tibial anterior-posterior translation and internal/external rotation on the wear of polyethylene tibial inserts in total knee replacements (Anatomic Graduated Component knees). The wear rate was the lowest in experiment (Exp.) 1, without translation and rotation [1.74 mg/million (mg/Mc) cycles]. In Exp. 2, with +/-5 degrees tibial rotation added, the wear rate increased to 10.6 mg/Mc. In Exp. 3, with rotation and -12 mm tibial translation added, the wear rate was 15.1 mg/Mc, whereas in Exp. 4, with rotation and +12 mm tibial translation, the wear rate was 18.7 mg/Mc. Internal/external rotation and anterior-posterior translation added a 6- to 11-fold increase in the wear rates of tibial knee inserts. The shapes of the tibial wear tracks were rectangular and the area of the track increased when rotation and translation were added.

Study of hip joint dislocation after total hip arthroplasty

The present study was undertaken to identify the factors responsible for hip joint dislocation after total hip arthroplasty, laying emphasis on analysis of the background variables of the patients. Of the 317 hips included in the study, ten (3.2%) dislocated. Only the anteversion angle of the cup differed significantly between the dislocation group and the dislocation-free group. The safe zone of the anteversion angle seems to be between 20 and 30 degrees. but it is also essential to set the antetorsion angle of the stem to match the shape of individual bones to create a more stable hip joint. This safe zone may be expanded by the additive effect of antetorsion angle of the stem.RésuméLe but de cette étude a été d’identifier les facteurs responsables d’uneluxation de la hanche après arthroplastie totale en insistant sur l’analysedes différents paramètres de chaque patient. Sur les 317 hanches inclusesdans cette étude, 10 (3,2%) ont présenté une luxation. La seule différencesignificative entre le groupe des sujets ayant présenté une luxation et ceuxn’en ayant pas présenté est l’angle d’antéversion de la cupule. L’angleoptimum d’antéversion de la cupule semble être compris entre 20 et 30 degrésmais il est également essentiel de lier l’angle d’antéversion avec l’angled’antétorsion de la pièce fémorale, celles-ci ayant été manufacturées surmesure et adaptées à la géométrie osseuse de chaque individu de façon àcréer une hanche parfaitement stable. Cette zone de sécurité peut êtreaméliorée par l’addition, à l’angle d’antéversion de la cupule de l’angled’antétorsion de la pièce fémorale.

A report of two cases of Werner's syndrome and review of the literature.

Two cases of Werners syndrome are reported. The first case is that of a man with grey hair since his 20s, and alopecia since aged about 50 years. At the age of 53 years, Werners syndrome was diagnosed, along with a malignant soft tissue tumour of the hand. The patient underwent ray amputation for the tumour. The subsequent histopathological diagnosis was synovial cell sarcoma, and the patient died of lung metastasis at 15 weeks postsurgery. The second case is that of a woman diagnosed with diabetes mellitus when aged 34 years. At 39 years, a bilateral cataract was diagnosed and at 40 years, diabetic gangrene of the left calcaneal region and calcaneal osteomyelitis necessitated left below-knee amputation. The incidence of Werners syndrome in Japan is extremely high (about 1000 of the around 1300 cases reported worldwide) compared to other countries. Most patients develop malignant tumour or arteriosclerosis, the most important complications of this syndrome. The average life expectancy for patients with Werners syndrome is 46 years. The incidence of epithelial cancer and mesenchymal sarcoma is 10 times that of the general population. The onset of symptoms of Werners syndrome generally precedes any later symptoms of associated conditions, such as malignant tumour. Therefore, early recognition of Werners syndrome is important to assist identification of malignant tumours at an early stage in this patient group.

Artificial hip joints: The biomaterials challenge.

What is new and what comes next in artificial hip joints? These are the crucial questions we attempt to answer after accurately surveying the state of the art in the field of hip arthroplasty, especially related to non-metallic materials. Summarizing the present situation, one could safely state that the current generation of hard-on-soft and hard-on-hard hip bearings has become quite effective in exhibiting extremely low degrees of wear when compared to traditional implants made of cobalt-chromium alloys coupled with conventional polyethylene materials or to the primitive alumina materials used in the past. Moreover, at a stage of more than 10 years in the clinical follow-up of new generations of hard-on-hard bearings, and more than 10 years follow-up for highly cross-linked polyethylene materials, we should soon be expecting a new set of officially compiled statistics that show significant reductions in failures due to particle-mediated osteolysis as compared to past statistical compilations. However, further important issues (other than wear) remain unsolved, including structural reliability of advanced ceramic and polyethylene components. Severe challenges yet stand in optimizing the biomaterials choice for significantly extended lifetimes and reduced failure risks. Moreover, joint healing trends are expected to evolve more radically in the next few decades.

Total sagittal spinal alignment in patients with lumbar canal stenosis accompanied by intermittent claudication.

Study Design. Cross-sectional study of total sagittal spinal alignment in lumbar spinal canal stenosis (LCS) patients with and without intermittent claudication. Objective. To evaluate total sagittal spinal alignment in LCS. Summary of Background Data. The sagittal spinal alignment is an important factor in the management of lumbar degenerative diseases and lower back pain. Patients with LCS accompanied by intermittent claudication adopt a forward-bending posture during walking. However, few studies have quantitatively assessed the abnormal posture in LCS in relation to clinical symptoms. Methods. This study analyzed 93 patients with LCS. They were divided into two groups according to the presence of neurogenic intermittent claudication; patients of the Claudicant group had intermittent claudication of the cauda equina (n = 53; mean age, 66.7) and those of the Nerve root group had no claudication (n = 40; mean age, 67.0). The following parameters were measured on the lateral whole-spine standing radiographs: the distance between the C7 plumb line and the posterior superior corner on the superior margin of S1 (sagittal vertical axis), the angle between the superior margin of the first lumbar vertebra and the first sacral vertebra (L1S1), lumbar lordotic angle, pelvic tilting angle (PA), and pelvic morphologic angle (PRS1). Results. The sagittal vertical axis of the Claudicant group (57.6 ± 37.5 mm) was significantly larger than that of the Nerve root group (40.3 ± 42.3 mm) and was larger in both groups compared with the standard values. Lumbar lordotic angle was smaller (18.8° ± 13.2°) and pelvic tilting angle was larger (27.2° ± 8.3°) in patients with the Claudicant group than those with the Nerve root group (22.4° ± 14.0° and 22.7° ± 7.2°, respectively). Conclusion. Patients of the Claudicant group exhibited forward bending of the trunk and pelvis backtilt, compared with those of the Nerve root group.

Chemotherapeutic agents sensitize sarcoma cell lines to tumor necrosis factor-related apoptosis-inducing ligand-induced caspase-8 activation, apoptosis and loss of mitochondrial membrane potential

Chemotherapeutic agents have been used for the treatment of patients with osteosarcoma (OS). However, inherent or acquired resistance to these agents is a serious problem in the management of OS patients. Tumor necrosis factor‐related apoptosis‐inducing ligand (TRAIL) is considered to induce apoptosis in a variety of cancer cells but not normal cells. In the present study, we examined whether chemotherapeutic agents enhance TRAIL‐induced apoptosis in the sarcoma cell lines MG‐63 and SaOS‐2. Pretreatment with sub‐toxic or slightly toxic concentrations of chemotherapeutic agents (cis‐diammine dichloroplatinum, CDDP and doxorubicin, DXR) sensitized both cell lines to TRAIL‐induced apoptosis, as assessed by the propidium iodide or Annexin V‐Cy5 staining method. These cell lines expressed death receptors TRAIL‐receptor 1 (TRAIL‐R1) and TRAIL‐R2, which were unaltered by treatment with CDDP, as assessed by flow cytometry. The decoy receptors TRAIL‐R3 and ‐R4 were barely detected in both cell lines. CDDP down‐regulated c‐FLIP, tending to lower the activation threshold required for TRAIL‐induced caspase‐8 activation. The CDDP‐pretreated cells indeed demonstrated more increased TRAIL‐mediated caspase‐8 activation, loss of mitochondrial membrane potential (ΔΨm), and apoptosis than untreated cells. Consequently, the activated caspase‐8 might lead to either activation of effector caspases such as caspase‐3 or loss in ΔΨm. Both the increased caspase activation and mitochondrial dysfunction induced by combination of CDDP and TRAIL would contribute to enhanced apoptotic cell death. The results of the present study would be valuable for the design of novel treatment modalities for patients with OS.

Highly crosslinked polyethylenes in hip replacements : Improved wear performance or paradox?

The lubrication and wear of artificial joints are important issues for their longevity. Bone loss caused by the biological response (osteolysis) to the wear debris leads to implant loosening and eventual failure of the device. Various studies have shown that the size, shape, and the number of particles are important factors in the osteolytic response to wear debris. It has been demonstrated that both submicron-size particles and long fibrils can stimulate macrophage responses. This paper examines the clinical and laboratory data on highly crosslinked polyethylene (XLPE) regarding implant wear and particulate debris. In simulator studies, total hip replacements have shown greatly reduced wear with XLPE cups compared with conventional polyethylene (PE) and short-term clinical studies of XLPE have now also shown reduced levels of wear. However, simulator studies have also demonstrated that adverse wear conditions can partially or completely negate the wear advantage of XLPE. Additionally, it has been shown that the XLPE debris particles are smaller than conventional PE. In a paradoxical manner, the decreased wear rate of XLPE should decrease the osteolytic potential, but the decreased debris size may have the potential to increase the biological activity. Therefore, the long-term clinical performance of XLPE is not clear at this time. Long-term clinical follow-ups will be needed to determine the actual benefit of XLPE in patients.

The radiographic study in the relationship of the glenohumeral joint

Accurate reproduction of anatomic relationship is important in non‐constrained prosthetic arthroplasty. The accurate lateral glenohumeral offset, which indicates a parameter of the lever arm of the deltoid and supraspinatus muscles, is one of the most important elements in achieving the efficient shoulder functions after prosthetic reconstruction. However, to our knowledge, there has been no detailed study on the influence of minute changes in the neck shaft angle, within the normal range, on lateral glenohumeral offset. In this study, we evaluated the relationship between the neck shaft angle and various geometric measurement values in the glenohumeral joint.