Yoshiharu Katoh

Water diffusion pathway, swelling pressure, and biomechanical properties of the intervertebral disc during compression load.

The behavior of water in the intervertebral disc of pig tail and its physiologic and biomechanical properties were investigated in relation to compression load. The water content, chemical composition, and swelling pressure in the intervertebral disc were measured, and the mechanism of the generation of the swelling pressure in relation to compression load stress was studied. The swelling pressure, through regulation of the water content of the disc and the resistance of the external load, differs with the region of the intervertebral disc. In the nucleus pulposus and the inner layer of the anulus fibrosus, the swelling pressure rises in proportion to the load, but few changes occur in the outer layer of the anulus fibrosus, and the constant pressure environment is thus maintained. The tritiated water (3H2O) uptake of the disc under various loads was measured. The molar partition coefficient of tritiated water is almost equal to 1 even under a compression load, which suggests that water is freely exchangeable. The diffusion of 3H2O in the intervertebral disc was traced using two pathway models: the perianular route and the end-plate route. The diffusion of water in the unloaded disc for both uptake and washout was about 2 to 3 times larger in the perianular route than in the end-plate route. Under load, the water diffusion was inhibited in both pathways. The relation between the load and displacement revealed viscoelastic properties indicating creep and stress relaxation. Youngs modulus and the stiffness increased with a rise in load speed. In a prolonged preloaded disc, preservation of high physical stiffness increased the stability of the disc against the impaction load, and the smaller internal dissipation demonstrated the deterioration of the shock-absorbing function of the disc. These findings provide new information on the effects of a prolonged load on metabolism and biomechanical properties of the intervertebral disc.

Occipito-cervical fusion reinforced by Luque's segmental spinal instrumentation for rheumatoid diseases.

Thirteen rheumatoid patients who suffered from severe neck-occipital pain with or without myelopathy due to cranio-cervical instability, were operated on using a modified U-shaped rod. Twelve of them concomitantly had lower cervical rheumatoid lesions. Average extent of fusion was 5.9 levels. Bone union was confirmed in twelve cases in which autogenous bone graft had been used at approximately 4 months postoperatively; methylmethacrylate was used in the remaining one case. Good alignment of the cervical spine also was obtained in 12 cases; one patient experienced occipito-C2 shortening after an additional surgery for deep infection. Improvement of neck-occipital pain was noted in all cases, and seven of eight patients with myelopathy showed neurologic recovery.

Morphometric analysis of subchondral bone of the tibial condyle in osteoarthrosis

Tibial condyles in 11 patients with knee joint osteoarthrosis were analyzed by subchondral bone morphometry using 11 static parameters. The results were evaluated by comparison with the grade of joint cartilage degeneration in relation to the external, intermediate, and internal areas of the tibial condyle. The bone morphometric data also were analyzed according to the depth of layers, from the surface to the depth of 2000 microns of the bone. A parallel relationship between the bone volume/bone formation activity and the Mankin grade of cartilage degeneration was noted in both medial and lateral condyles. Bone resorption activity in the medial condyle was found only in the external and intermediate areas; it was extremely low in the lateral condyle. Throughout the observation areas, the values of bone volume in relation to depth were highest in the superficial layer with a gradual decrease as the depth increased. The bone formation activity was highest in the superficial layer in the lateral condyle, whereas in the medial condyle, it was highest in the layer between 1000 and 1500 microns in depth. The bone resorption activity showed no variations according to the depth. The progression of joint cartilage degeneration was associated with remodeling of the underlying subchondral bone.

Results of expansive laminoplasty for lumbar spinal stenosis in active manual workers

Expansive laminoplasty was done on 18 selected patients with lumbar spinal canal stenosis who were active manual workers and 2 patients with cauda equina tumors from 1982 to 1990. Postoperative follow-up on the lnitial 10 cases of spinal stenosis was 1–7 years (mean, 3 years). Using computed tomography, the spinal canal was found to be enlarged with a nearly rectangular shape, and the mean percent eniargement was 119% (1.9 cm2). Spinal stability also was reinforced. The preoperative mean evaluation score (Japanese Orthopaedic Association score) was 10.4 (full scale, 29). The mean score improved to 24 postoperatively (mean percent improvement, 73%). These findings did not change during the long follow-up, and the satisfactory results were maintained.

RT-PCR Suggests Human Skeletal Muscle Origin of Alveolar Soft-Part Sarcoma

In 1952, Christopherson et al. proposed that alveolar soft-part sarcoma (ASPS) was a distinct entity with unique clinical and pathological features. Since their report, its histogenesis has not been determined. In order to clarify the histogenesis of ASPS, a study using reverse transcription polymerase chain reaction using cDNAs from MyoD1 and myogenin, and the actin filament from human-skeletal-muscle-related mRNAs has been performed in 5 cases of ASPS. The expression of MyoD1 and myogenin was determined in 5 and 2 cases of the 5 cases, respectively. Moreover, expression of the many mRNAs from the actin filament of skeletal muscle was also found in ASPS. According to these findings, it is now postulated that ASPS is of skeletal muscle origin.

Complications of Lateral C1-2 Puncture Myelography

This study reviewed the technical complication of 112 cases of lateral C1-2 puncture myelography for cervical spinal cord disorders. Spinal cord puncture and contrast injection, puncture between the occiput and C1, and blood vessel puncture were the main complications. These principally depended on the positioning of the patients neck (hyperextension) and misdirection of the x-ray beam. For preventing major arterial puncture, the authors also reviewed 164 vertebral angiograms and determined the pathway of the vertebral arteries and the incidence of anomaly.

Posterior Decompression for Cervical Ossification of the Posterior Longitudinal Ligament

Characteristics of ossification of the posterior longitudinal ligament (OPLL) in the cervical spine are (1) reducing the space available for the spinal cord (SAC) and causing compressive myelopathy, (2) extending cranially to C2 or above, (3) diminishing the cervical rangeof-motion, and (4) generally occurring in older people over 50 years old. The basic strategy of treatment in patients with myelopathy caused by cervical OPLL is decompression for the cervical cord and removal of OPLL if readily done.

Effects of Ceramic Interspinous Block on Anterior Lumbar Interbody Fusion

Anterior interbody fusion (AIF) for degenerative lumbar disk and/or infectious diseases promises the most stable long-term performance for patients. However, this type of surgery necessitates long periods of rest and abstention from work to obtain a sound bony union, and the union failure rate is relatively high. Results of lumbar AIF using autogenous bone grafts have been reported by many authors, but the fusion rate varied from 56% to 94% [1–9].

Non-Instrumentation Stabilization / Decompression Procedure for Lumbar Spinal Stenosis: Significance of Expansive Laminoplasty

In the surgical treatment of various types of spinal stenosis, adequate decompression of the nerve roots and maintenance of spinal stability are essential. When spinal instability or degenerative spinal malalignment exists, extensive laminectomy impairs the mechanical integrity of the posterior supportive structures, and acceleration of the spinal instability and symptom recurrence may occur.