Introduction Rupture of the patellar tendon after total knee arthroplasty is an infrequent but serious complication. Several methods for treating this catastrophic complication have been described. The purpose of this article was to evaluate the results of semitendinosus graft augmentation with direct repair in the treatment of patellar tendon rupture after total knee arthroplasty. Material and methods From 2012 to 2014, six patients who underwent cemented total knee arthroplasty without patellar resurfacing presented with patellar tendon rupture after operation. Patellar tendon repair and augmentation with autogenous ipsilateral semitendinosus graft was scheduled with preparation of stocks of primary and revision prosthesis. Results All knees required revision either all components or one of the components. Postoperative radiograph confirmed that normal patellar height was with good alignment of all prosthesis components. Patients were followed up for average 1.5 years. No intra-or postoperative complications were recorded. Functionally, scores at final follow-up were excellent in two patients and good in four patients according to Knee Society clinical rating scores. The average active range of motion is from 10 to 135°. All patients could return to their daily activities without pain. Conclusion The right alignment and rotation of the knee prosthesis, together with good surgical technique in a primary operation, are the most important factors to avoid the catastrophic complication of patellar tendon rupture during or after the total knee arthroplasty. However, if patellar tendon rupture does occur, the use of our operative technique and rehabilitation program can bring good functional results.