The rotator cuff is composed of the subscapularis, supraspinatus, infraspinatus, and teres minor muscles and plays a crucial role in the movement of the shoulder joint. Rotator cuff tears are one of the most common causes of shoulder pain and dysfunction. The number of outpatient visits and surgeries for rotator cuff tears is increasing and will continue to rise as the population ages. The incidence of rotator cuff injury in athletes increases dramatically, especially in antagonistic and overhead-throwing sports. Massive rotator cuff tear (MRCT) refers to a rotator cuff defect of more than 5 cm or involving two or more rotator cuff tendons, which cannot be repaired entirely due to tendon retraction, fatty infiltration, or muscle atrophy. It is called an irreparable rotator cuff tear (IRCT) . After rotator cuff injury, patients presented with obvious shoulder pain and dysfunction. Superior capsule reconstruction (SCR) for the treatment of IRCT was first proposed by Mihata and has achieved good clinical outcomes. However, there are still some patients with postoperative retears. The main area of retear after rotator cuff injury occurs at the tendon-bone junction in the rotator cuff footmark area. The main reason is that the tendon-bone junction fails to form true tendon-bone healing but scar healing after rotator cuff repair. There are a variety of grafts available for SCR surgery, but all of them are soft grafts. The final healing mode of humeral foot marks is tendon-bone union, and the healing strength is lower than that of the normal tendon-bone junction.

To investigate the healing effect of autologous patella quadriceps femoris tendon graft in repairing massive rotator cuff injury in rabbits.

Thirty-six healthy adult rabbits were randomly divided into three groups: the control group (n=12) , the suture repair group (n=12) , and the graft repair group (n=12) . In the control group, the shoulder joint was cut open, the rotator cuff tendon was exposed, and the wound was sutured. In the suture repair group, the severed rotator cuff tendon was sutured to the greater tuberosity of the humerus by transosseous suture. In the graft group, the patella quadriceps femoris tendon graft was sutured to the rotator cuff rupture, the patella was fixed to the greater tubercle of the humerus, and the quadriceps femoris tendon was fixed to the glenoid. Six weeks after the operation, six rabbits in each group were sacrificed for biomechanical testing. Eight weeks after the procedure, six rabbits in each group were sacrificed for histomorphological analysis.

The results of the biomechanical study showed that the maximum tension of the graft repair group was significantly higher than that of the suture repair group (P<0.05) , and there was no significant difference between the graft repair group and the control group. Histological analysis showed that the patella and humerus healed well in the graft repair group. In the suture repair group, the tendon-bone was not well recovered at the suture site, and the fibrous tissue at the humerus junction was loose.

Autologous patella quadriceps femoris tendon repair of massive rotator cuff injury in rabbits can replace tendon-bone healing with bone-bone healing in the humerus and achieve better healing strength.