ABSTRACT
Objective To observe the effect of bone marrow-derived mesenchymal stem cells (bMSCs) on graft healing within a bone tunnel after anterior cruciate ligament (ACL) reconstruction in rabbits.Methods The study involved 24 New Zealand white rabbits undergone ACL reconstruction with an autologous ipsilateral gastrocnemius tendon graft.Both hindlimbs were included.In one hindlimb,graft coated with fibrin glue compound by bMSCs was employed (bMSCs group).Whereas in the contralateral hindlimb,graft coated with fibrin glue without cells was employed (control group).At postoperative 2,4,6 and 8 weeks,specimens were harvested to have a biomechanical test of tensile strength and stiffness of tendon-bone interface.Results Tensile strength and stiffness of tendon-bone interface in both experiment and control groups presented a rising trend with the prolong of repair time.In contrast,significantly higher tensile strength and stiffness of tendon-bone interface were observed in experiment group since the 6 weeks (P ＜ 0.05).Conclusion bMSCs transplantation significantly enhances the early tensile strength and stiffness at tendon-bone interface after ACL reconstruction in rabbits and improves the graft healing within a bone tunnel.
ABSTRACT
ObjectiveTo develop an EZ screw remover for screwing out the skidded screws,discuss its design features and biomechanical characteristics and verify its extracting effect by clinical applications.MethodsFresh skeleton specimens were used in the study,including the femur (n =3),tibia ( n =3 ),radius and ulna ( n =3 ).The screws were fixed to the specimens according to clinical requirements and bone cement was filled into the medullary cavity.The specimens were randomized into three biomechanical test model groups,ie,Group A (measuring the skidded screws with the biggest torsion when the screws were taken out by screwdriver),Group B (measuring the skidded screws with the biggest torsion when the screws were taken out by one handle of EZ screw remover) and Group C ( measuring the skidded screws with the biggest torsion when the screws were taken out by two handles).The fixed screws were divided into two types of φ4.5 mm and φ3.5 mm.The experimental specimens were tested on the universal testing machines to measure the maximum torque,torsion angle,power consumption value and efficiency when drawing out the screws. The experimental data were compared between groups.The skidded screws encountered in clinical were taken out with EZ screw remover to verify the extracting effect.ResultsThe pullout torque in Groups A,B and C was 2.87-3.27 N · m,3.06-4.83N · m and 4.12-8.36 N · m respectively ( P ＜ 0.05 ).The average torsion angle value in each corresponding group was 0.77°,0.28°,0.16° respectively (P ＜ 0.05 ).When the screws were screwed out,the average power consumption was 21 J,32 J and 45 J in Groups A,B and C respectively and power ( mechanical efficiency) was 0.35 J/s,0.53 J/s and 0.75J/s in Groups A,B and C respectively,with significant differences ( P ＜ 0.05 ).Seventeen pieces of the cannulated skidded screws of φ7.3 mm in seven patients were successfully taken out by using the EZ screw remover.ConclusionEZ screw removerhas enough resistance strength and rigidity to torsion as well as powerful clamping force and hence is an ideal tool for screwing out the skidded screw in orthopedics.
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Objective To observe the biomechanical effect of sacroiliac screw fixation with dif-ferent needling points in treatment of extorsion pelvic instabihty so as to provide experimental basis for clinical application. Methods Ten fresh adult pelvis specimens were fixated by sacroiliac screw with needling points B (2.5 cm anterior to posteroinferior iliac spine and 40. cm posterior to greater sciatic notch), A (0.1 cm anterior to the same horizontal plane of point B) and C ( 1.0 cm posterior to the same horinzontal plane of point B). The shifting of the pubic symphysis diastasis and the sacroiliac joint crack under the same extorsion force was measured in integrity ligament group, point A group, point B group and point C group to compare the stability of different needling points. Results In confronting extor-sion force, integrity ligament group and point C group were obviously inferior to point A group and point B group (P<0.05 ) but there was no statistical difference between point B group and point A group (P > 0.05). As for the stability of the sacroiliac joint, there was statistical difference among all groups ( P < 0.05 ), while there was no statistical difference between integrity ligament group and point B group ( P > 0.05). Conclusion Point B is the most stable, safe and effective needling point.
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@#Objective To investigate the design and clinical result of the modified medial fasciocutaneous flap of lower leg in the different zonation. Methods The length of lower leg was divided into three zonations equally.According to the different zonation of the fasciocutaneous flap,the 45 patients were divided into three groups from Jan.2005 to Feb.2008.The defects of the patients were repaired with the flaps.The sizes of the flaps ranged from 5 cm×3 cm to 25 cm×10 cm.Results The flaps survived completely in 43 cases.The distal sides of flaps necrosed partially in 2 cases in the upper third of the lower leg.The necrosed part of the flap was repaired after the change dressings.The colour and texture of flaps were excellent,the appearance and function were satisfactory after a follow up of 4-20 months.Conclusion The modified medial fasciocutaneous flap of the lower leg is easy to design and dissect,blood supply is reliable without sacrifice of the major arteries.The flap can be used according to the different location of the fascia pedicel.It is the idea flap to repair the soft tissue defects of the front of knee joint,the leg,the ankle and the foot.