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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.  Treatment of stress fracture of the olecranon in throwing athletes with internal fixation through a small incision 
The present study is a report of retrospective case series of stress fracture of the olecranon. Six patients presented posterior elbow pain in throwing in baseball and softball, but fracture was not diagnosed in radiographs. We detected stress fracture of the olecranon using computed tomographic (CT) scan and treated the patient with internal fixation with a headless cannulated double threaded screw through a small skin incision. All patients returned to competitive level without elbow complaints after the operation.
When throwing athletes present with unusual posterior elbow pain and no significant findings on radiographs, a CT scan examination should be performed. We recommend surgical treatment of internal fixation with a screw through a small skin incision, as a good option for stress fracture of the olecranon in order to allow early return to sports activity in competitive athletes.
PMCID: PMC3541177  PMID: 23241173
Stress fracture; Elbow; Olecranon; Throwing athlete
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.  Pneumocephalus Associated with Cerebrospinal Fluid Fistula as a Complication of Spinal Surgery: A Case Report 
Case Reports in Medicine  2010;2010:328103.
Pneumocephalus is a well-known condition following head trauma, but is rare as an injury or as a result of surgery of the spine. We present a 76-year-old patient with a rare case of pneumocephalus associated with a cerebrospinal fluid fistula as a complication of surgical treatment for cervical myelopathy. Although cerebrospinal fluid leakage was noted and the injured dura was carefully sutured at operation, tension pneumocephalus occurred. The resultant pneumocephalus was diagnosed based on neurogenic symptoms including sudden convulsion, head radiograph, and computed tomography scan. The benign course of the pneumocephalus postdiagnosis did not require secondary operation.
PMCID: PMC2892666  PMID: 20589216
7.  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
8.  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
9.  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.
10.  Surgical Treatment of Stress Fracture of the Scaphoid of an Adolescent Gymnast 
Stress fracture of the carpal scaphoid is very rare. We present stress fracture of the scaphoid in an adolescent gymnast who was treated with internal fixation.
Key pointsThere is a risk of stress fracture of the scaphoid in gymnast.Internal fixation with a screw is one of the good options for stress fracture of the scaphoid.
PMCID: PMC3761527  PMID: 24149614
Stress fracture; scaphoid; gymnast.
11.  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.
12.  A Palmar Fracture-Dislocation of the Proximal Interphalangeal Joint of the Middle Finger Caused by Bowling: A Case Report 
During bowling, a twenty year old man could not pull out his middle finger from the ball in release and injured his finger. X-ray revealed a palmar fracture- dislocation of the PIP joint. We manipulated the PIP joint, but a gap remained at the fracture site on the X-ray after reduction. Surgical treatment was performed with a screw. Postoperatively, the middle finger was fixed with a splint for two weeks, and then active range of motion exercises were started. One year after the operation, the fracture had healed with a congruous joint surface, and the patient had full range of motion in the middle finger with no difficulties in activities of daily living. The etiology of a palmar fracture-dislocation of the PIP joint is still controversial, but we suggested the mechanism of the fracture-dislocation was caused by a shearing force to the middle phalangeal base from a dorsal direction. The main cause of the current injury was the poor fit between the middle finger and the hole of the bowling ball. Bowling is a popular and safe sport, but we should be aware of unexpected hand injuries related to bowling which may occur, especially in players at a recreational level.
Key pointsWe presented a palmar fracture-dislocation of the PIP joint in a middle finger that occured while bowling.We discussed the mechanism and suggested the main cause of the injury was the poor fit between the middle finger and the hole of the bowling ball.We advised that while bowling is recognized as a safe sport, due to its popularity we should be aware of unexpected hand injuries which may occur, especially in players at a recreational level.
PMCID: PMC3737785  PMID: 24150568
Palmal fracture-dislocation; PIP joint; bowling; sports
13.  Comparison of mechanical and histological properties between the immature and mature tendon attachment 
International Orthopaedics  2002;26(5):318-321.
We tested the tensile strength of the Achilles tendon attachment to the calcaneus in skeletal mature and immature rabbits. The mean ultimate failure load was 179.6±28.6 N in the mature animals, and 138.5±36.1 N in the immature animals (P<0.05). Although direct insertion was clearly observed histologically in the mature animals, direct insertion was not obvious in the immature animals. In the mature animals, failure occurred partly at the attachment zone (50%) and partly at the tendon zone (50%). In the immature animals, failure occurred at the attachment zone in 85% and at the tendon zone in 15%.
PMCID: PMC3620985  PMID: 12378363

Results 1-13 (13)