Jitsuhiko Shikata

Spinal deformity and instability after multilevel cervical laminectomy.

Sixty-four patients who had undergone multilevel cervical laminectomy were studied for postoperative spinal deformity and instability. Special attention was given to patients with cervical spondylosis (CS), ossification of the posterior longitudinal ligament (OPLL), and spinal cord tumors. Twenty-three (36%) of 64 patients showed postoperative changes in curvature type and 9 (14%) had developed spinal deformity (kyphotic or meandering-type curvature). In two juvenile patients, the deformity developed soon after operation and spinal fusion was required to prevent neurologic complications. In the adult cases, contrary to the hitherto accepted concept, long-term follow-up revealed the tendency of the deformity to develop more frequently in OPLL cases than in CS cases. Mobility of the cervical spine was reduced considerably after laminectomy, both in CS and OPLL cases. There was no adult patient who required further operation for severe deformity or instability after laminectomy. Extensive laminectomy, even including the C2 lamina, seemed to have no adverse effect on the stability of the cervical spine.

ANALYSIS AND PREVENTION OF SPINAL COLUMN DEFORMITY FOLLOWING CERVICAL LAMINECTOMY I : PATHOGENETIC ANALYSIS OF POSTLAMINECTOMY DEFORMITIES

Postlaminectomy deformities were simulated in the cervical or cervicothoracic spine by the use of a displacement incremental method based on finite-element analysis combined with composite material and spanning element theory. The simulation analyses revealed that the primary cause of postlaminectomy deformity was the resection of one or more spinous processes and/or posterior ligaments (ie, ligamenta flava, supraspinous, and interspinous ligaments). After their removal, the tensile stresses that were preoperatively distributed through the posterior ligaments were transferred to the facets. This led to an imbalance of the stresses on the spinal bodies, causing deformity. The gravitational center of the head determined whether the deformity would develop as a kyphosis or increasing lordosis. As the elastic modulus of the soft tissue composites (eg, end plates, ligaments, and facets) increased, a kyphotic deformity changed gradually from swan-neck deformity, to extreme kyphotic deformity with a large curvature, and finally to a straightening deformity. Progressive kyphotic deformity is found only in children.

Surgical treatment for paraplegia resulting from vertebral fractures in senile osteoporosis.

Seven extremely rare cases of paraplegia secondary to senile osteoporotic vertebral compression fractures were treated by posterior decompression followed by Harrington rod stabilization. This approach not only ensures more satisfactory decompression, but also facilitates early mobilization and rehabilitation. The follow-up period ranged from 1 year to 3 years, 3 months (average, 24.7 months); in all seven cases a substantial overall improvement was achieved. This report demonstrates that an osteoporotic vertebral body fracture can cause a cord compression, and emphasizes the effectiveness and importance of early surgical treatment.

Extensive En bloc resection of regionally recurrent carcinoma of the rectum

To remove regionally recurrent cancer of the rectum completely, more radical extensive resections were attempted than the conventional ones in 35 patients. Twenty‐two patients underwent total pelvic exentera‐tion. In 23, sacral resection was done, combined with other procedures including excision of the entire circumference of the lower pelvic ring. There were two hospital deaths. Delayed wound healing was seen in ten. Preoperative severe pain was alleviated in 18. Also, perineal ulcer, vaginal bleeding, bloody stools, and tenesmus disappeared. Of the four 5‐year survivors (estimated rate, 23%), only one was disease‐free. A second recurrence was seen in 27 patients, of whom 23 had regional failure. It was concluded that so‐called local recurrence is a lesion more widespread than indicated by imaging and biopsy. Therefore, even the most radical resection rarely can cure this disease. However, such a surgical procedure can afford more effective palliation than other treatments and may prolong life in selected patients significantly.

Ultrasound measurement of vertebral rotation in idiopathic scoliosis

Ultrasound can be used to outline the spinous processes and the laminae, and thus to measure axial rotation. Using our own technique, we measured vertebral rotation in 47 patients with idiopathic scoliosis. There was a strong linear relationship between the Cobb angle and the rotation of the apical vertebra in untreated patients, but this relationship was lost in patients who had had brace treatment. Vertebral rotation can easily be measured by ultrasound. This is a harmless and fairly rapid investigation which can be used at routine follow-up examination of patients with idiopathic scoliosis.

EXPERIMENTAL STUDIES OF THE ELASTIC FIBER OF THE CAPSULAR LIGAMENT: INFLUENCE OF AGEING AND SEX HORMONES ON THE HIP JOINT CAPSULE OF RATS

Physiological changes with advancing age and the influence of sex hormones on elastin in the hip joint capsule of rats were studied both biochemically and morphologically. Elastin content of the joint capsule was greater in females than in males at 10 weeks of age. Staining of ultrathin sections with Verhoeff iron hematoxylin followed by lead citrate (VIH-LC) demonstrated that the elastic fibers of specimens from infant rats were characterized by a small elastin core formed by aggregation of elastin fibrils in the center of closely packed microfibrils. With advancing age the diameter of the elastic fiber of the hip joint capsule tended to increase gradually in both sexes until sexual maturation was reached. In specimens from adult rats, the elastic fiber consisted of an increased solid elastin core surrounded by loosely packed microfibrils. The diameter of the elastic fiber and the ratio of the central elastin to the peripheral microfibrils were greater in females than in males after sexual maturation. Th...

Long-term results over 10 years of anterior corpectomy and fusion for multilevel cervical myelopathy.

Study Design. Retrospective long-term outcome analysis over more than 10 years. Objectives. To assess the long-term results of anterior corpectomy and fibular strut grafting over ≥4 disc levels for cervical myelopathy, and identify factors affecting the late deterioration in clinical outcome. Summary of Background Data. Few studies have shown long-term results after anterior corpectomy and strut grafting. There is little detailed information about the long-term effects of multilevel anterior corpectomy and fusion for cervical myelopathy. Methods. A total of 31 cases were available for the 10-year follow-up after surgery (86% follow-up rate). Clinical results and radiographic measurements were obtained before surgery, 3 months after surgery, and at follow-up. Results. There were 3 patients who had deterioration of the Japanese Orthopedic Association score of 1 point because of increasing hand numbness; 1 patient had adjacent disc degeneration, and 1 had pseudarthrosis without additional stenosis on magnetic resonance imaging. Adjacent disc degeneration did not affect the clinical results (P = 0.76). Conclusions. The long-term follow-up showed stable clinical results for more than 10 years, which depended on the thorough removal of the possible causes of the myelopathy, such as ossification of the posterior longitudinal ligament or a degenerated disc. Adjacent disc degeneration has minimal effects on the long-term clinical results after anterior long fusion.

Lumbar posterolateral fusion with biphasic calcium phosphate ceramic.

The authors conducted a retrospective observational study of patients who needed lumbar posterolateral fusion (PLF) using a biphasic calcium phosphate ceramic implant as a substitute for bone graft. The findings of clinical, radiographic, and histologic examinations were reviewed. Thirty-two patients underwent single-level PLF with instrumentation. In all cases, to decrease the occurrence of donor-site complications and morbidity, locally harvested morselized bone from the decompressive site was mixed with hydroxyapatite and beta-tricalcium phosphate (HAP-TCP) granules and sticks and used for fusion at the posterolateral aspect of the lumbar spine. The histologic findings of three biopsy specimens obtained during second operations for metallic implant removal were reviewed. The minimum follow-up period was 26 months. There was no evidence of instrument loosening or breakage. However, bone-graft incorporation was difficult to evaluate radiographically, because image quality was inferior to that with conventional autogenous iliac bone graft. Partial graft bone resorption was revealed on radiographs in 75% of cases. The results showed clinical improvement in all but one case. Solid fusion was observed during the second operation in all three cases. Histologic analysis showed excellent bone incorporation around the HAP-TCP granules. These findings suggest that, although the bulk of the fusion mass with HAP-TCP was smaller than that with autogenous bone, this technique combined with rigid instrumentation is a safe and effective procedure.

Replacement of the lumbar vertebrae of sheep with ceramic prostheses

We prepared a prosthesis for the replacement of the lumbar vertebrae of sheep, using apatite- and wollastonite-containing glass-ceramic. The material is stronger than human cortical bone and has the special feature of chemical bonding to bone. Ten sheep underwent replacement of L3 and L4 vertebrae, without bone grafting. The animals were killed at intervals from three months to 27 months after operation, and the interface between the prosthesis and bone was examined radiologically, histologically and crystallographically. Bone bonding with the prosthesis had occurred in half the implants. It took at least one year for bonding to be complete, but an apatite layer on the surface of the prosthesis was observed as early as three months after the operation, suggesting the possibility of much earlier bone bonding if more rigid fixation of the prosthesis had been provided.

Changes in collagen cross-linking and lysyl oxidase by estrogen

Dermal collagen solubility and lysyl oxidase activity of bones were measured in DDD mice of advancing age. Insoluble fractions of the dermal collagen increased more rapidly in females than in males after 5 weeks of age. Activity of the lysyl oxidase extracted from bones was higher in females than in males after 4 weeks of age. After sexual maturation, such sex differences were always observed in skin as well as in bone tissue. In other experimental animals, dermal collagen solubility was markedly decreased by estrogen treatment and lysyl oxidase was remarkably activated by estrogen in both skin and bone. Thus it is clear that estrogen stimulates the enzyme activity and accelerates the maturation of collagen and elastin in extracellular space.