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1.  Ligament regeneration using an absorbable stent-shaped poly-l-lactic acid scaffold in a rabbit model 
International Orthopaedics  2012;36(11):2379-2386.
Ligaments are frequently damaged in sports activities and trauma, and severe ligament injury can lead to joint instability and osteoarthritis. In this study, we aimed to regenerate the medial collateral ligament (MCL) using an absorbable stent-shaped poly-l-lactic acid (PLLA) scaffold in a rabbit model to examine the biocompatibility and mechanical properties.
Twenty-three Japanese white rabbits were used in this study. MCL defects were surgically created in the knee joints and then reconstructed using stent-shaped PLLA scaffolds. As controls, flexor digitorum longus (FDL) tendons were implanted into the contralateral knees. Seven rabbits were sacrificed at three time points, conducted four, eight and 16 weeks after the operation. The regenerated tissues were histologically evaluated using fibre alignment scoring, morphology of fibroblast scoring and immunohistochemical analysis of types I and III collagen. The regenerated tissues were also biomechanically evaluated by measuring the ultimate failure load and stiffness.
At four weeks post-operation, spindle-shaped cells were observed on the inside of the scaffolds. At eight weeks, maturation of the regenerated tissues and collagen fibre alignment parallel to the ligaments was observed. At 16 weeks, the fibre alignment had become denser. The fibre alignment and morphology of fibroblast scores significantly increased in a time-dependent manner. Expression of type I collagen was more strongly observed in the scaffold group at eight and 16 weeks post-operation than at four weeks. Type III collagen was also observed at four, eight and 16 weeks post-operation. A thin layer of fibrocartilage was observed at the ligament-bone junction at eight and 16 weeks. The ultimate failure load of the scaffold group was 46.7 ± 20.7 N, 66.5 ± 11.0 N and 74.3 ± 11.5 N at four, eight and 16 weeks post-operation, respectively. There was no statistical difference between the normal MCL and the scaffold group at 16 weeks post-operation.
The stent-shaped PLLA scaffold allowed for MCL regeneration with type I collagen expression and fibrocartilage formation and resulted in sufficient mechanical function.
PMCID: PMC3479301  PMID: 22976595
2.  Arthroscopic Bony Bankart Repair Using Double-Threaded Headless Screw: A Case Report 
Case Reports in Orthopedics  2012;2012:789418.
We present a case of arthroscopic fixation for bony Bankart lesion using a double-threaded cannulated screw. A 39-year-old man sustained a left shoulder injury from a motorcycle accident. Radiographs showed bony Bankart lesion and CT revealed 40% defect of glenoid articular surface. Arthroscopic fixation was performed using double-threaded cannulated screw after the bony fragment was reduced by suturing the labrum at the edge with a suture anchor. Arthroscopic bony Bankart repair using double-threaded cannulated screw fixation is effective because compression force could be applied between bony fragments and the screw head is not exposed in the glenohumeral joint.
PMCID: PMC3505899  PMID: 23227392
3.  Application of layered poly (L-lactic acid) cell free scaffold in a rabbit rotator cuff defect model 
This study evaluated the application of a layered cell free poly (L-lactic acid) (PLLA) scaffold to regenerate an infraspinatus tendon defect in a rabbit model. We hypothesized that PLLA scaffold without cultivated cells would lead to regeneration of tissue with mechanical properties similar to reattached infraspinatus without tendon defects.
Layered PLLA fabric with a smooth surface on one side and a pile-finished surface on the other side was used. Novel form of layered PLLA scaffold was created by superimposing 2 PLLA fabrics. Defects of the infraspinatus tendon were created in 32 rabbits and the PLLA scaffolds were transplanted, four rabbits were used as normal control. Contralateral infraspinatus tendons were reattached to humeral head without scaffold implantation. Histological and mechanical evaluations were performed at 4, 8, and 16 weeks after operation.
At 4 weeks postoperatively, cell migration was observed in the interstice of the PLLA fibers. Regenerated tissue was directly connected to the bone composed mainly of type III collagen, at 16 weeks postoperatively. The ultimate failure load increased in a time-dependent manner and no statistical difference was seen between normal infraspinatus tendon and scaffold group at 8 and 16 weeks postoperatively. There were no differences between scaffold group and reattach group at each time of point. The stiffness did not improve significantly in both groups.
A novel form of layered PLLA scaffold has the potential to induce cell migration into the scaffold and to bridge the tendon defect with mechanical properties similar to reattached infraspinatus tendon model.
PMCID: PMC3245426  PMID: 22136125
4.  Potency of double-layered Poly L-lactic Acid scaffold in tissue engineering of tendon tissue 
International Orthopaedics  2009;34(8):1327-1332.
A successful scaffold for use in tendon tissue engineering requires a high affinity for living organisms and the ability to maintain its mechanical strength until maturation of the regenerated tissue. We compared two types of poly(L-lactic acid) (PLLA) scaffolds for use in tendon regeneration, a plain-woven PLLA fabric (fabric P) with a smooth surface only and a double layered PLLA fabric (fabric D) with a smooth surface on one side and a rough (pile-finished) surface on the other side. These two types of fabric were implanted into the back muscles of rabbits and evaluated at three and six weeks after implantation. Histological examination showed collagen tissues were highly regenerated on the rough surface of fabric D. On the other hand, liner cell attachment was seen in the smooth surface of fabric P and fabric D. The total DNA amount was significantly higher in fabric D. Additionally, mechanical examination showed fabric P had lost its mechanical strength by six weeks after implantation, while the strength of fabric D was maintained. Fabric D had more cell migration on one side and less cell adhesion on the other side and maintained its initial strength. Thus, a novel form of double-layered PLLA fabric has the potential to be used as a scaffold in tendon regeneration.
PMCID: PMC2989087  PMID: 19960193
5.  Autologous osteochondral plug transplantation for osteochondrosis of the second metatarsal head: a case report 
Osteochondrosis of the second or third metatarsal head is a rare condition called Freiberg's disease. To relieve foot pain, conservative treatment with a foot orthosis to reduce weight-bearing and immobilize the foot are recommended. In cases in which such treatments have proved to be ineffective, several surgical treatments have been performed. The appropriate surgical treatment for Freiberg's disease remains controversial.
Case presentation
We describe the case of a 20-year-old Japanese woman with a three-year history of right forefoot pain and no history of trauma. Two years after treatment by autologous osteochondral plug transplantation, she has neither complaints nor symptoms.
Autologous osteochondral plug transplantation represents a potentially successful surgical arthroplastic option in preserving the metatarsophalangeal joint in patients with Freiberg's disease.
PMCID: PMC3224451  PMID: 21752253
6.  The effect of porosity and mechanical property of a synthetic polymer scaffold on repair of osteochondral defects 
International Orthopaedics  2008;33(3):821-828.
We have made three types of poly (DL-lactide-co-glycolide) (PLG) scaffolds (porosity: scaffold I 80 ± 0.9%, II 85 ± 0.8%, III 92 ± 0.7%; compression module determined with 10% strain: scaffold I 0.26 MPa, II 0.091 MPa, III 0.0047 MPa). Osteochondral defects made in the femoral condyle of rabbits were treated with these scaffolds and the possibilities of cartilage repair were investigated histologically. At post-operative weeks 6 and 12, histological scores in the groups of scaffolds II and III were significantly higher than the score in the group of scaffold I. Scaffolds II and III, which have higher porosity than scaffold I, allow better migration of bone marrow cells and better replacement of the scaffold with bone and cartilage than scaffold I. This study suggests that higher porosity allowing bone marrow cells to migrate to the scaffold is important in repairing osteochondral defects.
PMCID: PMC2903104  PMID: 18415099
7.  The effect of fibroblast growth factor-2 on autologous osteochondral transplantation 
International Orthopaedics  2007;33(1):275-280.
In this study, we performed a mechanical analysis of the effect of fibroblast growth factor-2 (FGF-2) on autologous osteochondral transplantation in a rabbit model. A full-thickness cartilage defect (diameter: 5 mm; depth: 5 mm) made in the right femoral condyle was treated with osteochondral transplantation using an osteochondral plug (diameter: 6 mm; depth: 5 mm) taken from the left femoral condyle. The animals were divided into three groups: Group I, the defect was filled with 0.1 ml of gelatin hydrogel containing 1 μg of FGF-2; Group II, the defect was filled with 0.1 ml of gelatin hydrogel only; Group III, the defect was left untreated. Thereafter, osteochondral plugs were transplanted and the transplanted osteochondral grafts were evaluated mechanically and histologically at postoperative weeks 1, 3, 8 and 12. The structural property of the osteochondral graft was significantly greater in Group I than in Groups II and III at postoperative week 3. Histological analysis at 3 weeks revealed a tendency towards increased subchondral bone trabeculae in Group I compared with the other groups. Autologous osteochondral grafts transplanted with gelatin hydrogel containing FGF-2 acquired adequate stiffness at an early postoperative phase.
PMCID: PMC2899235  PMID: 17940768
8.  Subcutaneous Peroneus Longus Tendon Rupture Associated with OS Peroneum Fracture 
We report a rare case of subcutaneous peroneus longus tendon rupture associated with os peroneum fracture. Three dimensional computed tomographic scan was useful to understand this disorder. We treated the patient with excision of fractured os peroneum and tenodesis of the proximal stump of the ruptured peroneus longus tendon to the lateral aspect of the calcaneus.
Key pointsIn order to understand a rare case of subcutaneous peroneus longus tendon rupture associated with os peroneum fracture, three dimensional computed tomographic scan was useful.The patient was treated with excision of fractured os peroneum and tenodesis of the proximal stump of the ruptured peroneus longus tendon to the lateral aspect of the calcaneus.
PMCID: PMC3761522  PMID: 24149615
Os peroneum; fracture; rupture; peroneus longus tendon.
9.  Stress Fracture of the First Rib in a High School Weight Lifter 
A 17-year-old boy, who played a weight lifting in high school, sustained stress fracture of the first rib without any causes. We successfully treated first rib stress fracture with limitation of using the upper extremity and with using low-intensity pulsed ultrasound.
Key pointsStress fracture of the first rib in a weight lifter was successfully treated with limitation of sports activity and with LIPUS treatment.
PMCID: PMC3761492  PMID: 24149543
Stress fracture; low-intensity pulsed ultrasound; first rib; weight lifting.

Results 1-9 (9)