ObjectiveTo investigate the effectiveness of modified patellar tendon reconstruction using hamstring autograft in the treatment of chronic patellar tendon rupture and defects.MethodsThe clinical data of 11 patients with chronic patellar tendon rupture and defects admitted between January 2015 and August 2018 were retrospectively analyzed. The patient were treated with inverted U-shaped reconstruction technique using hamstring autografts, in which 2 bone tunnels were created at the level of 1/2 and lower 3/4 of the patella, and 1 bone tunnel was created beneath the tibial tuberosity. There were 8 males and 3 females with an average age of 30.1 years (range, 10-61 years). The average interval from the primary injury to the operation was 9.5 months (range, 2-36 months). According to Yousef classification, there were 7 cases of type A2, 3 cases of type B2, and 1 case of type C2. The length of the patella tendon defect was measured when the patella was reducted intraoperatively with an average of 4.5 cm (range, 2.7-7.1 cm). Subjective function scores [including International Knee Documentation Committee (IKDC) subjective score, Tegner activity level, and Lysholm score] were evaluated before operation and at last follow-up. The loss of knee extension, Caton index, and thigh circumference difference at 15 cm above the patella between bilateral limbs were also measured.ResultsAll patients were followed up 24-66 months (mean, 34.2 months). All incisions were primary healing, and there were no complications such as wound infection, venous thrombosis of the lower extremities, stiffness of the knee joint, graft failure, neurovascular injury, etc. No second revision surgery was performed during the follow-up. At last follow-up, the subjective function scores (IKDC subjective score, Tegner activity level, Lysholm score), loss of knee extension, thigh circumference difference, and Caton index were significantly improved when compared with those before operation (P<0.05). Two patients still had patella alta, with Caton indexes of 1.29 and 1.32, respectively.ConclusionIn the treatment of chronic patellar tendon ruptures and defects, the modified patellar tendon reconstruction using hamstring autograft can significantly improve the postoperative knee function, restore the normal range of knee extension, enhance the extensor and correct the patella alta.