Biomedical subjects

Hirotaka Sano

Publications and source records attributed to Hirotaka Sano.

10 recordsLinked to original sources

PubMed2007

Stress distribution in the supraspinatus tendon after tendon repair: suture anchors versus transosseous suture fixation.

BACKGROUND: The stress concentration at the site of supraspinatus tendon repair, either by suture anchor fixation or by transosseous suture fixation, has not been fully clarified. HYPOTHESIS: Suture anchor fixation showed higher stress concentrations in the tendon than did transosseous suture fixation. STUDY DESIGN: Controlled laboratory study. METHODS: Three finite element models were developed based on a previously published model of normal supraspinatus tendon (0 degrees abduction). Single-row fixation, double-row fixation, and transosseous suture fixation were simulated. A tensile force was applied to the proximal end of the supraspinatus tendon to simulate its contraction force. RESULTS: In the single-row model, the stress appeared from the site of the anchor and extended into the proximal tendon. The highest stress concentration was observed on the bursal surface of the tendon. The double-row model showed a similar pattern to the single-row model except that the stress concentration was observed only around the medial anchor. In the transosseous model, the stress appeared from the attachment site to a bony trough, which extended proximally into the tendon substance. No significant stress concentration was observed inside the tendon. CONCLUSION: Both single-row and double-row fixations showed higher stress concentration inside the tendon than did transosseous suture fixation. CLINICAL RELEVANCE: A high stress concentration might be a cause of the rerupture often observed after arthroscopic cuff repair using suture anchors.

Adaptation, Physiological↗

PubMed2006

Non-mineralized fibrocartilage shows the lowest elastic modulus in the rabbit supraspinatus tendon insertion: measurement with scanning acoustic microscopy.

The acoustic properties of rabbit supraspinatus tendon insertions were measured by scanning acoustic microscopy. After cutting parallel to the supraspinatus tendon fibers, specimens were fixed with 10% neutralized formalin, embedded in paraffin, and sectioned. Both the sound speed and the attenuation constant were measured at the insertion site. The 2-dimensional distribution of the sound speed and that of the attenuation constant were displayed with color-coded scales. The acoustic properties reflected both the histologic architecture and the collagen type. In the tendon proper and the non-mineralized fibrocartilage, the sound speed and attenuation constant gradually decreased as the predominant collagen type changed from I to II. In the mineralized fibrocartilage, they increased markedly with the mineralization of the fibrocartilaginous tissue. These results indicate that the non-mineralized fibrocartilage shows the lowest elastic modulus among 4 zones at the insertion site, which could be interpreted as an adaptation to various types of biomechanical stress.

Adaptation, Physiological↗

PubMed2006

Does decalcification alter the tissue sound speed of rabbit supraspinatus tendon insertion? In vitro measurement using scanning acoustic microscopy.

Failure of the tendon or ligament insertions is one of the most common injuries in the Orthopaedic field. To elucidate the pathogenesis of those injuries, the authors had attempted to measure the tissue sound speed that could be correlated to its elasticity using scanning acoustic microscopy (SAM). For the application of SAM to tendon or ligament insertions, it was necessary to determine the role of decalcification in SAM measurements since mineralized tissues including bone or mineralized fibrocartilage were present at the insertion site. To assess whether decalcification alters the tissue sound speed or not, supraspinatus tendon insertion of six Japanese white rabbits were measured with SAM operating in the frequency range of 50-150 MHz. Right supraspinatus tendons attached to the humeral head were cut into two pieces at the center of the tendon. Then, they were fixed with 10% neutralized formalin for 12 h. In each specimen, medial half was not decalcified, while lateral half was decalcified with ethylene-diamine-tetra-acetic acid (EDTA). After embedding in paraffin, 5 microm thick specimens were prepared for the measurement using SAM. The mean sound speed in each histologic zone was evaluated, and subsequently compared to that measured in the undecalcified and the decalcified specimens. Mean sound speed of non-mineralized fibrocartilage was 1544 m/s in the undecalcified specimens, while the value of 1541 m/s was determined in the decalcified ones. On the other hand, it decreased 2-3% after decalcification in the mineralized tissue including mineralized fibrocartilage and bone (mineralized fibrocartilage: undecalcified = 1648 m/s, decalcified = 1604 m/s; bone: undecalcified = 1716 m/s, decalcified = 1677 m/s). However, no significant differences were found between the undecalcified and the decalcified specimens (non-mineralized fibrocartilage: p = 0.84, mineralized fibrocartilage: p = 0.35, bone: p = 0.28). These results indicate that SAM could be applied to determine the properties of the tendon or the ligament insertions after decalcification with EDTA. Although SAM is applicable only for in vitro experimental study, it is expected that these data will contribute to better understanding concerning the biomechanics of tendon or ligament insertions as well as the pathogenesis of their failure at a microscopic level.

Animals↗

PubMed2006

Recurrent Crow-Fukase syndrome associated with increased serum levels of vascular endothelial growth factor: a case report and review of the literature.

Crow-Fukase syndrome (CFS) is a rare multi-system disorder, characterized by polyneuropathy, organomegaly, endocrinopathy, M-proteins, skin changes and anasarca, with or without myeloma. The pathophysiology, diagnosis, and treatment of CFS are controversial. CFS may be associated with the overproduction of vascular endothelial growth factor (VEGF). However, there have been no reports of monitoring the serum VEGF level after recurrence, to the best of our knowledge. We report a 54-year-old man with CFS presenting with a 3-year history of ascites, anasarca, weakness of the lower extremities, and plasmacytoma in the scapula. At the initial examination, the VEGF level was 1,590 pg/ml (the VEGF level of a healthy control, 78.4 +/- 75.2 pg/ml). After initial treatment with chemotherapy and irradiation of the affected shoulder, the VEGF level decreased to 154 pg/ml and the symptoms disappeared. Twenty one months later, gate disturbance and anasarca recurred, and the VEGF level was over 2,000 pg/dl. After total scaplectomy, the VEGF level decreased to 730 pg/dl and the symptoms disappeared. The serum level of VEGF well correlated to the clinical course of the patient. In conclusion, measurement of the VEGF level is useful for diagnosing CFS and for monitoring its clinical course.

Bone and Bones↗

PubMed2004

Repeated hemarthrosis with massive rotator cuff tear.

An 80-year-old woman with repeated hemarthrosis of the right shoulder was examined and treated arthroscopically. Plain radiographs indicated narrowing of the acromiohumeral interval (3 mm) with large acromial spur. Under fluoroscopic visualization, the impingement between the humeral head and the medial edge of the acromion was seen at 50 degrees abduction. The area of impingement of the humeral head seemed to be just medial to the greater tuberosity. Arthroscopically, a crater formation was seen at this site. Active bleeding was seen at the center of the crater, which was interpreted as the principal cause of intra-articular hemorrhaging. The undersurface of the acromion was irregular because of the presence of osteophyte. At 50 degrees abduction, the crater impinged with the medial edge of the acromion. We assume that both the presence of osteophyte and the instability caused by the massive rotator cuff tear might contribute to the attrition of the humeral head. In this patient, intra-articular hemorrhaging was successfully treated arthroscopically by coagulation of the bleeding point with minimal abrasion of the undersurface of the acromion. We believe that the arthroscopy facilitated the clinical management of the repeated hemarthrosis with massive rotator cuff tear.

Aged↗

PubMed2004

Super bone scan due to bone marrow metastases appearing 19 years after surgery for early gastric cancer--a case report.

A 54 year old man presenting a so-called super bone scan is reported. The patient had a past history of subtotal gastrectomy due to early gastric cancer 19 years previously. Laboratory data indicated microcytic anemia and high serum alkaline phosphatase. Both the serum calcium and phosphate levels were within normal ranges. In spite of extensive examination for a primary malignant lesion in the organs including the remaining stomach, no solid tumors were identified. Pathological examinations revealed that the tumor cells in the biopsy specimen from the lumbar spine were almost identical to those in the gastric cancer excised 19 years previously. We considered that micrometastases in the bone marrow existed at the time of the initial surgery for gastric cancer and reappeared 19 years later showing super bone scan.

Adenocarcinoma↗

PubMedDate not supplied

Stress distribution in the supraspinatus tendon with partial-thickness tears: an analysis using two-dimensional finite element model.

The purpose of this study was to clarify the stress distribution in the rotator cuff tendon with 3 types of partial-thickness tears by use of 2-dimensional finite element analysis. In the finite element model of the normal human shoulder, a tendon defect was created on the articular surface, on the bursal surface, or in the midsubstance close to the insertion. A tensile force was applied to the proximal end of the tendon, and the stress distribution was calculated. In all 3 types of tears, a high stress concentration appeared around the articular surface at the insertion and at the site of the tear, which extended proximally. The maximum value of the von Mises stress increased with the presence of a partial-thickness tear. With the arm in abduction, a high stress concentration was also observed around the site of the tear. These biomechanical conditions of the supraspinatus tendon may eventually lead to a full-thickness tear at the critical zone.

Finite Element Analysis↗

PubMedDate not supplied

Mechanical environment of the supraspinatus tendon: a two-dimensional finite element model analysis.

We performed 2-dimensional finite element model analysis to estimate the mechanical environment of the supraspinatus tendon. The geometric shape of the finite element model was determined by magnetic resonance imaging of a normal human shoulder obtained at 0 degrees, 30 degrees, and 60 degrees of abduction, whereas the histologic location of noncalcified and calcified fibrocartilage was determined from a cadaveric specimen. The supraspinatus tendon was pulled proximally with the force of 10 N at 0 degrees, 53 N at 30 degrees, and 115 N at 60 degrees of abduction. The area of high principal stress maximum was observed on the articular side of the supraspinatus tendon, which shifted toward the insertion as the arm was abducted. High stress concentration on the articular side of the supraspinatus tendon near its insertion during arm elevation may explain the frequent occurrence of rotator cuff tears at this site.

Adult↗

PubMedDate not supplied

Experimental fascial autografting for the supraspinatus tendon defect: remodeling process of the grafted fascia and the insertion into bone.

To elucidate the postoperative histologic changes of fascial autografting, tendinous defects (1.5 x 1.5 cm) were created close to the supraspinatus insertion and were covered by fascial autografts in 21 rabbits. Shoulders harvested on the fourth day and 1, 2, 3, 4, 6, and 8 weeks after surgery were examined histologically and immunohistochemically. At the fascia-bone junction, chondrocytes started to appear at 2 weeks after surgery and increased rapidly thereafter. Although a tidemark was not seen, remodeling of direct insertion with fibrocartilage was almost complete by 8 weeks. The distribution of collagen types II and III represented a pattern similar to that of a normal supraspinatus tendon insertion. In the grafted fascia, the cellular density showed a marked increase over time (r2 = 0.74, P <.0001). Our study revealed that both the tendinous tissue and its insertion were reformed after this procedure. Fascial autografting might be useful for repairing a supraspinatus tendon defect.

Animals↗

PubMedDate not supplied

Tensile strength of the supraspinatus after reimplantation into a bony trough: an experimental study in rabbits.

The goals of this study were to determine the strength of the supraspinatus tendon after reimplantation into a bony trough and to find out whether the fibrocartilaginous enthesis reformed. In 21 rabbits, the supraspinatus tendon was transected and reinserted into a bony trough at the greater tuberosity. After sacrifice at 8 and 12 weeks, tensile strength was measured. Microscopically, the presence of fibrocartilage and the spatial orientation of the cartilage columns and collagen fibers were assessed. At sacrifice, 14 of 21 reinserted specimens had healed successfully and were studied. Most mechanical failures occurred through bone, and none failed at the site of reimplantation. The mean peak loads of the operated tendons were significantly lower than their controls (8 weeks, 134.8 +/- 49.9 N vs 223.1 +/- 33.4 N, and 12 weeks, 172.2 +/- 68.2 N vs 274.1 +/- 70.0; P =.013 and P =.025, respectively). Histologically, at 8 weeks, the fibrocartilaginous enthesis had partially reformed; it was narrower than normal, and the collagen fibers had only partially assumed their normal spatial arrangement. Twelve weeks after reimplantation, 4 of 7 entheses had a normal histologic appearance. We conclude that return of strength of the supraspinatus tendon is evident 8 weeks after surgical reattachment into a bony trough and that the fibrocartilaginous enthesis is normal in over half of the specimens at 12 weeks. The subchondral bone was weaker than the reinserted tendon. The results support the clinical practice of surgical reimplantation. Avoiding active exercises early while promoting them later could improve the surgical results and reduce the effects of disuse.

Animals↗