Yoshikazu Ikuta

Transplanted neuronal progenitor cells in a peripheral nerve gap promote nerve repair

A basic experiment of peripheral nerve regeneration using neuronal progenitor cells embedded in collagen gel was performed in a rat sciatic nerve defect. First, when neuronal progenitor cells derived from the fetal rat hippocampus were cultured in atelocollagen-containing medium, neurospheres positive for anti-nestin antibody were confirmed after 8 days. These cells differentiated into astrocytes positive for anti-glial fibrillary acidic protein (GFAP) antibody, oligodendrocytes positive for anti-galactocerebroside (GalC) antibody and neurons positive for anti-neurofilament 200 (NF200) antibody, and they were capable of extending axons. They also differentiated into Schwann-like supportive cells positive for anti-s100 and anti-p75 antibody. Next, a 15-mm defect was prepared in the sciatic nerve of mature rats, and the nerve was bridged with a silicone tube filled with neuronal progenitor cells (1 x 10(5)) embedded in collagen gel. The transplanted neuronal progenitor cells were labeled in advance with 5-bromo-2-deoxyuridine (BrdU). When the regenerated tissue was examined 6 weeks and 10 weeks after grafting, the number and diameter of myelinated fibers were significantly increased compared with a control tube without neuronal progenitor cells. Action potentials were detected in the regenerated nerve. Also, cells positive for both anti-BrdU antibody and anti-S100 or anti-p75 antibody were observed in the regenerated tissue, and part of the grafted neural stem cells were considered to have differentiated into Schwann cell-like supportive cells. From these results neuronal progenitor cells derived from the fetal rat hippocampus are considered to retain their proliferative and differentiating abilities in collagen gel, and when transplanted to a site of peripheral nerve defect, part of them differentiate into supportive cells and they contributed to promotion of axonal regeneration.

Repair of flexor tendons by intratendinous tendon suture.

In a three year period, severed flexor tendons in the fingers and palm of 50 patients were repaired using an intratendinous suture method. The majority were secondary repairs, and 21 of 50 were in children less than 15 years of age. Results were satisfactory, with 79% being rated as good or excellent. The technique apparently causes little disturbance in the circulation, and if adhesions develop, they are limited and good results can be expected from tenolysis.

The anatomic relation among the nerve roots, intervertebral foramina, and intervertebral discs of the cervical spine

Study Design. An anatomic study of the cervical intervertebral foramina, nerve roots, and intradural rootlets performed using a surgical microscope. Objectives. To investigate the anatomy of cervical root compression, and to obtain the anatomic findings related to cervical foraminotomy for the treatment of cervical radiculopathy. Summary of Background Data. Cervical foraminotomy is a procedure performed frequently for the management of cervical radiculopathy. However, anatomic studies of cervical foraminotomy have not been fully elucidated. Methods. In this study, 18 cadavers were obtained for the study of the cervical spine. All the soft tissues were dissected from the cervical spine. Thereafter, laminectomy and facetectomy were performed on C4 through T1 using a surgical microscope. The nerve roots and surrounding anatomic structures, including intervertebral discs and foramina, were exposed. In addition, the intradural rootlets and their intersegmental connections were observed. Results. The shape of the intervertebral foramina approximated a funnel, the entrance zone being the most narrow part and the root sleeves conical, with their takeoff points from the central dural sac being the largest part. Therefore, compression of the nerve roots occurred at the entrance zone of the intervertebral foramina. Anteriorly, compression of the nerve roots was caused by protruding discs and osteophytes of the uncovertebral region, whereas the superior articular process, the ligamentum flavum, and the periradicular fibrous tissues affected the nerve posteriorly. The C5 nerve roots were found to exit over the middle aspect of the intervertebral disc, whereas the C6 and C7 nerve roots were found to traverse the proximal part of the disc. The C8 nerve roots had little overlap with the C7–T1 disc in the intervertebral foramen. The C6 and C7 rootlets passed two disc levels in the dural sac. Also, a high incidence of the intradural connections between the dorsal rootlets of C5, C6, and C7 segments was found. Conclusions. This study demonstrated the anatomy of the nerve roots, rootlets, and intervertebral foramina, and may aid in understanding the pathology of cervical radiculopathy. The presence of intradural connections between dorsal nerve roots and the relation between the course of the nerve root and the intervertebral disc may explain the clinical variation of symptoms resulting fromnerve root compression in the cervical spine. To perform cervical foraminotomy for cervical radiculopathy, it is necessary to understand the detailed anatomy of the intervertebral foramina thoroughly.

Beneficial effect of basic fibroblast growth factor on the repair of full-thickness defects in rabbit articular cartilage

Abstract The effects of exogenous basic fibroblast growth factor (bFGF) on the repair of full-thickness cartilage defects were examined. Four-millimeter diameter, cylindrical defects were made in rabbit articular cartilage and were filled with human recombinant bFGF. The addition of bFGF to the defect induced the formation of a thick cartilage layer composed of chondrocytes and a metachromatic-stained matrix after 6 weeks. The score of the bFGF-treated tissue, as evaluated by a semiquantitative histological scale, was significantly higher than that of the untreated tissue. At 24 weeks, the cartilage-like matrix that contained the proteoglycans and type II collagen was thicker in the bFGF-treated tissue than in the untreated tissue. Immunohistochemical analysis of the tissues at 6–12 weeks with an anti-bFGF monoclonal antibody suggested that a single application of bFGF increased the number of differentiating chondrocytes that synthesized bFGF at a high level. In contrast, immunostaining of the tissues at 6–12 weeks with a monoclonal antibody against proliferating cell nuclear antigen showed that the number of proliferating cells in the bFGF-treated tissue was fewer than in the untreated tissue. These findings suggest that administration of bFGF into cartilagenous defects promotes the differentiation of chondrocytes and their matrix synthesis, and that this growth factor is useful for improving cartilage repair.

Free muscle transplantation by microsurgical technique to treat severe Volkmann's contracture.

In a free muscle transfer, great care must be taken in selecting the muscle to be grafted. We have found the pectoralis major to be a good donor muscle. Although most muscles are not nourished by a single artery and a few veins, the vessels which enter the pectoralis major muscle with the nerves are the main nutrient vessels, and these vessels alone can adequately nourish this muscle. Neurorrhaphy should be performed at a site as close as possible to the muscle. Good indications for free muscle transfer are cases in which a flexor muscle has become necrotic, while the extensor muscle is viable--for example, if the flexor muscle has sustained traumatic crushing injury or if there is a Volkmanns contracture.

Meniscal repair enhanced by an interpositional free synovial autograft: An experimental study in rabbits

This report describes the methods and effectiveness of interpositional free synovial autografts (IPFSAs) in promoting the healing of lesions in the avascular portion of the knee joint meniscus in rabbits. Thirty-four specimens were divided into two groups: 17 in the study group and 17 in the control group. The medial meniscus of the left knee joint was excised in each rabbit, and an artificial longitudinal tear was created in the avascular zone of the meniscus. In the study group, an IPFSA was sewn into the tear with a single horizontal suture. In the control group, the tear was repaired without synovium in the same manner. The menisci were then implanted into the right knee joint in the respective animals. At intervals the animals were killed, and the menisci were examined grossly and microscopically. Three menisci were eliminated because they had become attached to the synovial wall. In the study group, the lesion completely healed by 4 weeks, except for one. The menisci in the control group never completely healed, particularly at the deeper levels of the lesion. At 8-16 weeks, autolysis of the specimens made microscopic examination difficult and unreliable in both groups. Based on these results, it has been concluded that an IPFSA can promote the healing process in the avascular zone of a torn meniscus in rabbits and that systemic vascularity to the synovium or the meniscus is not essential for healing to occur.

Ipsilateral osteochondral grafting for finger joint repair

A method for reconstructing articular osteochondral defects of the joint surfaces of the fingers is described. An osteochondral graft was harvested from the distal or proximal side of the second or third carpometacarpal joint of the ipsilateral hand. The graft was subsequently transplanted to the site of the defect in the proximal or distal interphalangeal joint. Ten cases with a follow-up period of more than 2 years were reviewed. The mean angular deformity decreased from 33 degrees to 4 degrees, and the mean active range of motion increased from 22 degrees to 38 degrees. Plain x-ray films revealed good joint congruity, and no donor site morbidity was appreciated. This treatment approach may be particularly useful in children.

The state of the articular cartilage at the time of surgery as an indication for rotational acetabular osteotomy

We have studied whether the state of the articular cartilage at the time of rotational acetabular osteotomy for dysplasia of the hip affects the outcome 2 to 5.5 years after surgery. Arthroscopy in 57 patients (59 joints) at the time of the operation showed grade-0 changes in seven, grade-1 in nine, grade-2 in 17, grade-3 in 14 and grade-4 in 12 joints, according to the classification of Outerbridge. There was radiological evidence of the progression of arthritis in four joints which were classified at arthroscopy as grade 4. Stepwise regression analysis showed that damage to acetabular or femoral articular cartilage significantly affected the progression of arthritis. We conclude that the short-term results of successful rotational acetabular osteotomy for dysplasia are affected by the state of the articular cartilage.

The Diagnostic Value of MRI in Traumatic Brachial Plexus Injury

Findings in 34 patients with traumatic brachial plexus injury documented by surgical exploration and intra-operative somatosensory-evoked potentials were correlated with findings on myelography and magnetic resonance imaging (MRI) to determine whether MRI can identify nerve root avulsion. The coronal and sagittal planes were not able to demonstrate avulsion of the individual nerve roots. The axial and axial oblique planes did provide useful information to determine which nerve root was avulsed in the upper plexus, although it was difficult to clearly delineate the lower cervical rootlets. The accuracy of MRI was 73% for C5 and 64% for C6 and that of myelograpby 63% for C5 and 64% for C6. Thus, the diagnostic accuracy of MRI for upper nerve roots was slightly superior to myelography. Although its primary diagnostic value is limited to the upper nerve roots whose avulsion is relatively difficult to diagnose by myelography, MRI can provide useful guidance in the waiting period prior to surgical exploration after brachial plexus injury.

A scanning electron microscope study of microvascular anastomoses.

The abdominal aortas of 30 rats were sutured under an operating microscope. The results were studied under a scanning electron microscope at 8 different periods after operation, ranging from 3 minutes to one month. The observations are presented.