Objective:To explore the biomechanical effect of platelet-rich plasma（PRP） on the tendon-to-bone healing of rotator cuff tissue in a New Zealand rabbit model of full-thickness supraspinatus tear.Methods:Sixty healthy New Zealand white rabbits were obtained and divided into three groups:PRP gel group

simple PRP group

and blank group.All the rabbits were subjected to full-thickness supraspinatus tear modeling on the left shoulder.For the PRP gel group

during the modeling

PRP gel was applied to the injury site and then a layer closure was performed; for the simple PRP group

PRP was provided in liquid form and the liquid PRP was injected into the injured tissue and its surrounding areas after suturing was completed; for the blank group

the injured site was sutured directly.At 4 and 8 weeks after operation

the shoulder joint specimens were taken and subjected to histological and biomechanical evaluations of tendon-to-bone juncture for healing status.Results:In the histological evaluation

there was no significant difference in ligament tissue maturity index（LTMI）score at each time point between the PRP gel group and the simple PRP group.The LTMI score at each time point was significantly higher in the PRP gel group and the simple PRP group than in the blank group（P < 0.05）.The LTMI scores were significantly higher at week 8 than at week 4 for the three groups（P < 0.01）.In the biomechanical evaluation

the tensile failure load（TFL）at each time point was significantly greater in the PRP gel group than in the simple PRP group and the blank group（P < 0.05 and P < 0.01）.The TFLs at weeks 4 and 8 were significantly greater in the simple PRP group than in the blank group（P < 0.01）.The TFLs were significantly greater at week 8 than at week 4 for the three groups（P < 0.01）.Conclusion:In rabbits with rotator cuff injury

PRP can promote tendon-to-bone healing to some degree

while PRP gel can better promote tendon-to-bone healing due to its improved biomechanical strength of healing sites.