ABSTRACT
Rotator cuff injuries are the most common cause of shoulder pain and dysfunction. Ideal animal shoulder models should have similar shoulder anatomy and function as human, and are able to replicate the microenvironment change after tendon injury. At present, a variety of animal models including rat, mouse, rabbit, sheep, canine, bovine, and primate have been used to study the mechanism of rotator cuff injury, effects of different repair techniques, and factors affecting tendon to bone healing. Although large animal models are more anatomically similar to humans, small animal models are more convenient in revealing the biological mechanism of rotator cuff injury and healing. Choosing appropriate animal models based on research objectives and establishing new small animal models play a critical role in revealing the mechanism of rotator cuff diseases and developing novel treating strategies.
Subject(s)
Animals , Cattle , Dogs , Mice , Rabbits , Rats , Disease Models, Animal , Rotator Cuff , Rotator Cuff Injuries , Sheep , Tendon Injuries , Wound HealingABSTRACT
Objective: To assess the effect of microfracture and biomimetic hydrogel scaffold on tendon-to-bone healing in a rabbit rotator cuff tear model. Methods: Gelatin and methacrylic anhydride were used to synthesize gelatin methacryloyl (GelMA). Then the GelMA were treated with ultraviolet rays and vacuum freeze-drying method to obtain a biomimetic hydrogel scaffold. The morphology of the scaffold was observed by gross observation and scanning electron microscope. Degradation of the scaffold was determined at different time points. Twenty-four adult New Zealand rabbits, weighting 2.8-3.5 kg and male or female, were surgically created the bilateral acute rotator cuff tear models. One shoulder was treated with microfractures on the footprint and transosseous suture (control group, n=24). The other shoulder was treated with the same way, except for putting the scaffold on the footprint before transosseous suture (experimental group, n=24). The general conditions of rabbits were observed postoperatively. Tendon-to-bone healing was evaluated by gross observation, Micro-CT, HE staining, and bio-mechanical testing at 4 and 8 weeks after operation. Results: The scaffold was white and has a porous structure with pore size of 31.7-89.9 μm, which degraded slowly in PBS solution. The degradation rate was about 95% at 18 days. All the rabbits survived to the completion of the experiment. Micro-CT showed that there was no obvious defect and re-tear at the tendon-to-bone interface in both groups. No difference was found in bone mineral density (BMD), tissue mineral density (TMD), and bone volume/total volume (BV/TV) between the two groups at 4 and 8 weeks postoperatively ( P>0.05). HE staining showed that the fibrous scar tissue was the main component at the tendon-to-bone interface in the control group at 4 and 8 weeks postoperatively; the disorderly arranged mineralized cartilage and fibrocartilage formation were observed at the tendon-to-bone interface in the experimental group at 4 weeks, and the orderly arranged cartilage formation was observed at 8 weeks. Besides, the tendon maturation scores of the experimental group were significantly higher than those of the control group at 4 and 8 weeks ( P0.05); the ultimate load to failure at 8 weeks was significantly higher in the experiment group than in the control group ( t=4.162, P=0.009), and no significant difference was found in stiffness between the two groups at 8 weeks ( t=2.286, P=0.071). Conclusion: Compared with microfracture alone, microfracture combined with biomimetic hydrogel scaffold can enhance tendon-to-bone healing and improve the ultimate load to failure in rabbits.
ABSTRACT
[Objective]To investigate the effect of reconstituted bone xenografts(RBX) on tendon-to-bone healing by means of imaging,histological and biomechanical studies.[Method]Anterior cruciate ligament(ACL) reconstruction was performed bilaterally in 25 skeletally mature rabbits using long digital extensor tendon grafts.RBX were implanted into the treated knee of each rabbit,with the contralateral knees as controls.Every three rabbits were killed at 2,6 and 12 weeks postoperatively for routine histological studies.The samples were processed through Micro CT and subsequent HE and toludine blue staining.The remaining 16 rabbits were sacrificed at 6 and 12 weeks.Their femur-tendon graft-tibia complexes were harvested for subsequent mechanical testing.[Result]At 6 and 12 weeks after operation,the values of BMD in the RBX group were higher than those in the control group(P
ABSTRACT
Objective To investigate the effect of two kinds of injected biomaterial combined with bone morphological protein (BMP) on tendon-to-bone healing after anterior cruciate ligament reconstruction (ACL) in rabbits. Methods ACL reconstruction was performed bilaterally in 50 skeletally mature rabbits using long digital extensor tendon grafts. Injected fibrin glue (FG) or injected calcium phosphate cements (CPC) combined with BMP were implanted into the treated knee of each rabbit,with the contralateral knees as controls. Every three rabbits were killed at 2,6 and 12 weeks postoperatively for routine histological studies. The samples were processed through Micro CT and subsequent HE and toludine blue staining. The remaining 16 rabbits were sacrificed at 6 and 12 weeks. Their femur-tendon graft-tibia complexes were harvested for subsequent mechanical testing. Results Imageological results showed that 6 weeks after operation,bone mineral density (BMD) values in FG-bBMP group were higher than those in CPC-bBMP group. However,12 weeks after operation,BMD values in CPC-bBMP group were the highest in the three groups. Histological findings of the interface between the tendon and bone differed in the three groups. Two weeks after operation,more chondrocyte-like cells that were fairly disorganized were noted between the tendon and bone in FG-bBMP group. Six weeks after operation,mature bone formation around the tendon was observed in FG-bBMP group while more immature bone ingrew toward implanted tendon in CPC-bBMP group; at 12 weeks,more chondrocyte cells and new bone formation were seen in CPC-bBMP group while a small quantity of mature bone was around tendon in FG-bBMP group. In biomechanical evaluation,the maximum pull-out load of the tendon from the bone tunnel was significantly higher in the two treatment groups than in the control group 6 and 12 weeks after operation (P