Kunio Ibaraki

Mobilization of a congenital proximal radioulnar synostosis with use of a free vascularized fascio-fat graft

We present the results of a new mobilization procedure for the treatment of a congenital proximal radioulnar synostosis in seven patients. The operative procedure included separation of the synostosis and placement of a free vascularized fascio-fat graft to prevent recurrent ankylosis. The average age at the time of the operation was eight years and two months (range, six years and four months to eleven years and ten months). All of the patients were boys who had no other congenital anomalies. The radial head was dislocated in all seven patients (anteriorly in two and posteriorly in five). The final four index operations included an osteotomy of the radius in order to reduce the dislocated radial head. The average duration of follow-up was three years and eight months (range, two years and four months to four years and five months). Preoperatively, the patients had had difficulty with holding a bowl of soup and accepting objects, such as coins, into the palm. Postoperatively, they were able to perform these activities. None of the patients had recurrent ankylosis or loss of the flap. The average supination was 26 degrees (range, 10 to 45 degrees), and the average pronation was 45 degrees (range, 10 to 80 degrees). The four patients who had had an osteotomy of the radius in addition to the index procedure did not have a dislocation of the radial head and had an average arc of motion of 83 degrees of pronation and supination. The three patients who had not had an osteotomy had a dislocation of the radial head and an average arc of motion of 40 degrees after the index procedure. These findings demonstrate that separation of a congenital radioulnar synostosis with a vascularized fascio-fat graft and osteotomy of the radius can achieve pronation and supination of the forearm.

The role of calcitonin gene-related peptide (CGRP) in macrophages: the presence of functional receptors and effects on proliferation and differentiation into osteoclast-like cells

It has been shown that both calcitonin gene-related peptide (CGRP) and amylin bind weakly to calcitonin (CT) receptors in osteoclast-like cells formed in vitro and inhibit bone resorption by a cAMP-dependent mechanism. Osteoclasts are thought to be derived from cells of the monocyte macrophage lineage, in which CGRP, but not CT, induces cAMP production. In this study, we determined the presence of functional receptors for CGRP in mouse alveolar macrophages and the effects of this peptide on proliferation and osteoclastic differentiation in mouse alveolar and bone marrow-derived macrophages. Human CT did not stimulate cAMP production in macrophages. Human CGRP stimulated cAMP production in mouse alveolar macrophages and bone marrow-derived macrophages dose-dependently. Human amylin, which has 43% homology with human CGRP, also stimulated these macrophages to produce cAMP, but only at a 100-fold higher concentration. The increment in cAMP production induced by human CGRP and amylin was abolished by the addition of human CGRP(8-37), a selective antagonist for CGRP receptors. Specific binding of [125I]human CGRP to alveolar macrophages was detected (dissociation constant, 2.5 x 10(-8) M; binding sites, 1.4 x 10(4)/cell). Amylin, but not CT, displaced the bound [125I]human CGRP from alveolar macrophages, but at a 100-fold higher concentration. No specific binding of [125I]human CT and [125I]human amylin to alveolar macrophages could be detected. Pretreatment with human CGRP for 24 h dose-dependently suppressed DNA synthesis in alveolar macrophages induced by granulocyte-macrophage colony-stimulating factor (GM-CSF). CGRP also suppressed the number of macrophage colonies formed from bone marrow cells induced by macrophage colony-stimulating factor (M-CSF).(ABSTRACT TRUNCATED AT 250 WORDS)

Packing with high-porosity hydroxyapatite cubes alone for the treatment of simple bone cyst

In 23 patients, simple bone cysts were treated by curettage followed by packing the cavity with cubes of high-porosity hydroxyapatite (HA). In 22 patients, HA was packed exclusively without autogeneic bone graft. Except in one patient who sustained pathologic fracture at the femoral diaphysis, HA was packed with a fibula strut graft. Each case had an uneventful postoperative course and was followed, on average, two years. Complete healing without cyst recurrence occurred in 18 cases (78%). In three cases--all rapidly growing children--a new cyst appeared between the epiphyseal plate and the HA packing, but the original cysts did not recur. In two multiloculated cysts, the cavities were not filled fully and healing was incomplete, yet there was no cyst recurrence. In the entire group, new bone surrounding HA was roentgenographically evident within an average of 2.3 months. Thus, the result of packing high-porosity HA for simple bone cysts compares favorably with the cure rates reported either with autogeneic bone graft, or topical steroid injection.

Free vascularized medial plantar flap with functioning abductor hallucis transfer for reconstruction of thenar defects

We devised a medial plantar flap with a functioning abductor hallucis for simultaneous reconstruction of thenar skin and muscle defects. The anatomy of the flap was studied in five cadaver dissections before surgical attempts were made in patients, who in this series included three men and one woman (average age 38 years, range 26 to 50 years). All patients were followed a minimum of 3 years (average 3 years and 9 months). In all cases, voluntary abduction of the thumb by the transferred abductor hallucis was achieved and confirmed by electromyography. The functioning medial plantar flap provides not only stable skin to the thenar area with sufficient thenar bulk but also satisfactory abduction of the thumb.

Effects of innervation on the distribution of acetylcholine receptors in regenerating skeletal muscles of adult chickens

In order to determine the roles of nerves in the formation of clusters of acetylcholine receptors (AChRs) during synaptogenesis, we examined the distribution of AChRs in denervated, nerve-transplanted (neurotized) muscles and in regenerated skeletal muscles of adult chickens by fluorescence microscopy using curaremimetic toxins. In the denervated muscles, many extrajunctional clusters developed at the periphery of some of the muscle nuclei of a single muscle fiber and continued to be present for up to 3 months. The AChR accumulations originally present at the neuromuscular junctions disappeared within 3 weeks. In the neurotized muscles, line-shaped AChR clusters developed at 4 days after transection of the original nerve, but no change in the distribution of AChRs had occurred even at 2 months after implantation of the foreign nerve. The line-shaped AChR clusters were found to be newly formed junctional clusters as they were associated with nerve terminals of similar shape and size. Some of both the line-shaped and extrajunctional clusters were formed at least partly by the redistribution of preexisting AChRs. Finally, based on the above observations, the regenerating muscle fibers in normal muscles and in denervated muscles were examined: The extrajunctional clusters appeared in both kinds of muscles at 2 weeks after injury. Afterward, during the innervation process, the line-shaped AChR clusters developed while the extrajunctional clusters disappeared in the innervated muscles. In contrast with this, in the absence of innervation, only the extrajunctional clusters continued to be present for up to 3 months. These results demonstrate clearly that the nerve not only induces the formation of junctional clusters at the contact site, but also prevents the formation of clusters at the extrajunctional region during synaptogenesis.

Solo Implantation of Porous Cuboidal Hydroxyapatite for the Treatment of Simple Bone Cysts

ABSRACT Solo packing of porous cuboidal hydroxiapatite (HAp) for the treatment of simple bone cyst was performed in 23 cases. New bone formation of the space around HAp in the cysts were demonstrated radiologically in a few months. Complete cure was confirmed in 19 cases(83%) followed over one year(average one year nine months). Even for the large expansive cysts which had been often ineffective by topical steroid injection, complete healing by packing of HAp alone was obtained. In three cases, the cavities were not fully packed with HAp because of bony septa in multilocular cysts. Only in one growing child, new cyst was recurred between the epiphyseal plate and the packed HAp. Thus, this treatment for simple bone cysts is recommended because of high curability and shorter contraction period compared to topical steroid injection, and also recommended because of less invasiveness compared to conventional autogenous bone graft.

Which Activates Mechanotransduction in Bone—Extracellular Fluid Flow or Mechanical Strain?

We have defined mechanocoupling as the transduction of applied mechanical forces into a local mechanical signal which bone cells can perceive. Two candidates for this localized phenomenon are substrate strain or fluid flow within the bone matrix. Studies using the rat tibial 4-point bending model show that dynamic loads but not static loads increase bone formation, suggesting fluid flow as the machanical determinant of bone adaptation. To study the effects of these candidates on the osteoblast, MC3T3-E1 cells were grown on type I collagen-coated plastic plates and subjected to 4-point bending. Varying levels of substrate strain and fluid effects can be created independently in this system. Osteopontin (OPN) mRNA expression was used to assess the anabolic response of MC3T3-E1 cells. When fluid flow was low, neither strain magnitude nor strain rate was correlated with OPN expression. However, a higher magnitude of fluid flow significantly increased OPN mRNA expression independent of the strain magnitude or rate. We conclude that extracellular fluid flow might be more important than deformation of cell substrate in bone formation in response to mechanical loading.

Posterior Lumbar Interbody Fusion with Pedicle Screws in the Treatment of Lytic and Degenerative Spondylolisthesis

Three fusion techniques—posterolateral fusion, posterior lumbar interbody fusion (PLIF), and anterior spinal fusion—have been used for the treatment of spondylolisthesis. In general, it seems more desirable to combine instrumentation with fusion when the slipping vertebra is unstable. The instrument not only provides rigid stability immediately after surgery, but also decreases the late correction loss.

Evaluation of Bone Mineral Densities in Ossification of Posterior Longitudinal Ligament Using Dual-Energy X-Ray Absorptiometry

Ossification of posterior longitudinal ligament (OPLL) is an abnormal ossification of the spinal ligament and sometimes causes severe compressive myelopathy. Because of frequent association with ossification of other spinal and skeletal ligaments, OPLL has been classified as a type of ankylosing spinal hyperostosis (ASH) [1], or diffuse idiopathic skeletal hyperostosis (DISH) [2,3]. Pathological chondral ossification and bone remodeling were observed following the thickening of the ligaments [4], but the etiology remains unknown. It is considered that both local factors, such as mechanical stress or bone morphogenic factors, and generalized factors such as heredity or hormones may play a role in ossification. The purpose of this study is to determine whether bone mineral densities of OPLL patients can be used as an indicator of generalized hyperostotic inclination. This was done by comparing their bone mineral densities (BMDs) with those of normal subjects.

An experimental study of drug treatment following acute peripheral nerve compression injury. Part 3: An effect of steroid treatment following epineurectomy.

Experiments in our laboratory have shown that steroid therapy commenced immediately before the operation prevents the functional deficit caused by silicone cuffs applied to intact sciatic nerves in rats. A further study showed that epineurectomy alone caused no significant functional deficit. In this experiments when compression was applied after removal of the epineurium the same dose of steroid used in our previous experiments proved unable to prevent the functional deficit.In intact nerves, it is probable that the trauma of cuff application caused edema of the intraneural pressure in the segment under the cuff and thus neuronal injury. The maximum injury and edema would occur in the epineurium, which can be prevented by steroid administration. Following epineurectomy edema of the perineurium and endoneurium resulted in a similar pressure increase that was not prevented by the steroids.