Nobuzo Matsui

Low-intensity pulsed ultrasound initiates bone healing in rat nonunion fracture model

Low‐intensity pulsed ultrasound exposure has been shown clinically to shorten the fracture repair process and to induce healing of nonunions in humans, but its mechanism of action remains unclear. In this study we investigated the effect and mechanism of low‐intensity pulsed ultrasound on nonunion fracture healing in rat tibias. A consistently reproducible nonunion was produced in rat tibias by muscle interposition without osteotomy. This model was produced by creating a closed tibial fracture with only the distal end of the tibialis anterior muscle interposed into the fracture site. One limb was noninvasively exposed to low‐intensity pulsed ultrasound (a 200‐millisecond burst of sine waves of 1.5 MHz, repeating at 1.0 kHz) for 20 minutes daily. The incident intensity was approximately 30 mW/cm2. Rats were killed at intervals between 2 and 6 weeks. The events were assessed by radiographs, microfocus X‐ray computed tomograms, and histologic examination. After 6 weeks of exposure, 7 of 14 nonunion fractures showed healing on radiologic assessment. The results of three‐dimensional microfocus X‐ray computed tomographic reconstruction and histologic examination also supported this finding. On the other hand, all control tibias remained in a state of nonunion during the same period. These results indicate that low‐intensity pulsed ultrasound promotes healing in the rat nonunion fracture model.

Influence of macrophage infiltration of herniated disc tissue on the production of matrix metalloproteinases leading to disc resorption.

Study Design. Herniated lumbar disc specimens were cocultured with peripheral blood mononuclear cells, and cells isolated from extruded disc were cultured to study the production of matrix metalloproteinases. Objective. To investigate the role of peripheral blood mononuclear cells infiltrating extruded discs and disc-derived cells in the production of matrix metalloproteinases. Summary of Background Data. Magnetic resonance imaging analysis of herniated disc patients revealed a progressive decrease in the size of herniated discs. Spontaneous regression of herniated disc is associated with infiltrating macrophages, and matrix metalloproteinases have been implicated in this phenomenon. However, the correlation between infiltrating macrophages and the production of matrix metalloproteinases has received little research attention. Methods. Each disc specimen was incubated with homologous peripheral blood mononuclear cells. The numbers of peripheral blood mononuclear cells attached to the surfaces of herniated discs were counted and the culture media was assayed for MMP-3. The cells isolated from herniated discs were incubated with cytokines and the production of matrix metalloproteinases was measured. Total RNA was extracted from herniated discs and RT-PCR was carried out. Results. Significantly larger numbers of peripheral blood mononuclear cells were attached to the surfaces of extruded discs, and higher amounts of MMP-3 were detected than those of control discs. The culture medium of extruded discs showed higher MMP-1 and MMP-3 production than those from controls. Significant enhancement of MMP-1 and MMP-3 mRNA expression was observed in the disc-derived cells stimulated with cytokines. Conclusion. These results suggest that peripheral blood mononuclear cells infiltrating extruded discs may secrete a variety of biologic materials capable of further recruiting monocytes into herniated discs in an autocrine fashion. Disc cells stimulated with cytokines showed enhanced production of matrix metalloproteinases, which might play an important role in spontaneous regression of disc materials.

Evaluation of Hamstring Strength and Tendon Regrowth After Harvesting for Anterior Cruciate Ligament Reconstruction

Background It is generally thought that tissue regeneration and good functional recovery can be expected after anterior cruciate ligament reconstruction using the hamstring tendons. However, persistent strength deficit in deep knee flexion has also been reported. Hypothesis Morphologic regeneration of the harvested hamstring tendon is not necessarily associated with its functional recovery. Study Design Retrospective follow-up study. Method Twenty-eight patients who underwent anterior cruciate ligament reconstruction with hamstring graft were evaluated after a minimum period of 2 years. Status of tendon regrowth was assessed by magnetic resonance imaging. To specifically analyze the functional deficit after graft harvest, the isometric hamstring strength was examined in a sitting position at 90° of flexion and a prone position at 90° and 110° of flexion. Then, the strength data were correlated with the extent of tendon regeneration. Results In 22 of the 28 patients, a regrowth of the semitendinosus tendon was found, whereas regeneration of the gracilis tendon was observed in 13 patients. In the evaluation of hamstring strength, the isometric peak torque was reduced to 86.2%, 54.6%, and 49.1%, respectively, in the aforementioned 3 postures as compared with the contralateral side. Conclusions Significant functional deficit of hamstring strength remains regardless of morphologic regeneration.

Posterior condylar offset and flexion in posterior cruciate-retaining and posterior stabilized TKA

BackgroundAnterior tibial translation associated with posterior impingement has been reported to be one of the factors limiting flexion after posterior cruciate-retaining (CR) total knee arthroplasty (TKA), especially when posterior condylar offset is decreased postoperatively. On the other hand, its effect on postoperative motion in posterior-stabilized (PS) TKA remains unknown. It has been demonstrated that PS TKA exhibits a consistent posterior femoral rollback during flexion. Thus, we hypothesized that the problem of posterior impingement can be avoided by use of PS TKA. In this study, we examined the relationship between postoperative posterior condylar offset and knee flexion in CR and PS TKAs.MethodsIn this study, analysis was performed for 20 subjects who underwent bilateral TKAs (one CR and one PS TKA) as well as another group of 50 PS TKAs. All patients could be tracked for a minimum of 2 years. The range of flexion was measured before operation and at follow-up. Preoperative and postoperative posterior condylar offset was evaluated on true lateral radiographs.ResultsAt the follow-up examination, the mean flexion angle was 123° in the CR knees and 131° in the PS knees with a significantly greater improvement observed for the latter group. In the roentgenographic measurement of the posterior condylar offset, no significant difference was observed between the preoperative and postoperative values both in the CR and PS knees. We divided the patients into two groups according to the change of posterior condylar offset. The first group (Group I) showed a decrease in the posterior condylar offset after surgery and the second group (Group II) showed no change or an increase. Subsequently, postoperative change in flexion was compared between Groups I and II for the CR and PS knees. A significant difference between Groups I and II was observed in the CR knees, while no difference was observed in the PS knees. The magnitude of postoperative posterior condylar offset did not correlate with an improvement in maximum flexion angle in the 50 PS knees.ConclusionsIt was shown that the magnitude of posterior condylar offset correlated with a postoperative change in flexion angle in CR knees, while no such correlation was observed in PS knees.

Low-intensity pulsed ultrasound enhances early healing of medial collateral ligament injuries in rats

To investigate the effect of low‐intensity pulsed ultrasound exposure on the healing of injured medial collateral ligaments.

Repeat tears of repaired menisci after arthroscopic confirmation of healing

We undertook 114 arthroscopic meniscal repairs in 111 patients and subsequently carried out second-look arthroscopy to confirm meniscal healing at a mean of 13 months after repair. Stable healing at the repaired site was seen in 90. Of these, however, 13 had another arthroscopy later for a further tear. The mean period between the repair and the observation of a repeat tear was 48 months. Of the 13 patients, 11 had returned to high activity levels (International Knee Documentation Committee level I or II) after the repair. An attempt should be made to preserve meniscal function by repairing tears, but even after arthroscopic confirmation of stable healing repaired menisci may tear again. The long-term rate of healing may not be as high as is currently reported. Second-look arthroscopy cannot predict late meniscal failure and may not be justified as a method of assessment for meniscal healing. Young patients engaged in arduous sporting activities should be reviewed regularly even after arthroscopic confirmation of healing.

A posterior-stabilized total knee arthroplasty shows condylar lift-off during deep knee bends.

This prospective randomized study was done to examine whether any difference in presentation of condyler lift-off exists between posterior cruciate-retaining and posterior-stabilized total knee arthroplasties. Fluoroscopic analysis of flexion kinematics under weightbearing condition was done for 18 patients who had bilateral paired total knee arthroplasties. The posterior cruciate-retaining and posterior-stabilized prostheses were from the same total knee arthroplasty series with comparable surface geometries and were implanted by one surgeon. At evaluation, five of 18 patients (28%) with posterior cruciate-retaining total knee arthroplasties had condylar lift-off, compared with 12 of 18 patients (67%) with posterior-stabilized total knee arthroplasties. Consequently, a significant difference in its incidence was seen between the groups. Condylar lift-off in posterior-stabilized knees was observed at various flexion angles, and one knee in this group had lift-off laterally and medially at different flexion angles. These findings raise concern that the higher incidence of condylar lift-off in posterior-stabilized total knee arthroplasty may lead to an increased wear rate of polyethylene associated with long-term prosthetic loosening.

Production of adrenomedullin from synovial cells in rheumatoid arthritis patients.

It was recently reported that plasma levels of adrenomedullin (AM), identified as a vasorelaxant peptide, are significantly higher in rheumatoid arthritis (RA) patients than in osteoarthritis (OA) patients. The objective of the present study was to elucidate AM production in synovial cells from patients with RA. Adrenomedullin mRNA was detected in cultured synovial cells from RA patients by reverse transcription polymerase chain reaction (RT-PCR). Immunohistochemical analysis demonstrated the presence of AM in synovial cells from RA patients. In addition, we investigated AM levels in knee joint fluids from RA and OA patients. Those from RA patients were elevated approximately threefold over those of OA patients. In this study, we demonstrated for the first time AM expression in synovial cells from RA patients and high levels of AM production in RA joint fluid.

Expression of Transcription Factor Sox9 in Rat L6 Myoblastic Cells

Muscle-derived cells can differentiate into chondrogenic cells. In our present study, we investigated the pattern of expression of Sox9, a transcription factor known to play a key role in chondrogenesis, in a rat myoblastic cell line, L6. In addition, we evaluated expression of type II collagen and myogenic regulatory markers by reverse-transcript polymerase chain reaction. We also investigated the effect of transforming growth factor (TGF)-β 3, which is known to induce chondrogenesis, on Sox9 mRNA expression. On the first day of culture, we observed a high expression of Sox9. However, on the seventh day of culture, there was a decline in the level of Sox9 and type II collagen mRNAs and an increased expression of Myf5 and myogenin mRNAs. Sox9 mRNA expression was increased after stimulation of TGF-β 3 at 2, 6, and 24 hr. Cartilage nodules were observed in L6 cells treated with TGF-β 3 and dexamethasone. These results indicated that L6 myoblasts originally possess the capacity to differentiate into chondrogenic cells, but that capacity is lost as the cells differentiate toward the myogenic lineage. In addition, TGF-β 3 may modulate Sox9 mRNA expression in L6 cells and retain the capacity to differentiate into chondrogenic lineage.

A new fibular osteotomy in association with high tibial osteotomy (a comparative study with conventional mid-third fibular osteotomy)

Abstract A new technique for dividing the fibula when performing a high tibial osteotomy is described. The head of the fibula is enucleated and morselized. The technique is simple and safe with a low complication rate.Résumé En cas d’ostéotomie supérieure du tibia, nous décrivons une nouvelle technique d’ostéotomie péronière avec énucléation et morcellement de la tête du péroné. On peut employer pour ce faire la même incision cutanée que pour l’ostéotomie du tibia. L’incidence de complications est faible.