Quadriceps tendon rupture is an uncommon injury. This disabling condition is the result of direct or indirect trauma. It requires surgical repair to avoid poor outcomes in cases of neglected or chronic rupture. In most acute cases, simple tendon suture or reinsertion is suitable for an extensor mechanism reconstruction of the knee joint. However, chronic lesions often require a tendon graft or flap reconstruction. We report a case of a 15-year-old male who was diagnosed with a chronic quadriceps rupture with a patellar superior pole fracture. We performed quadriceps reconstruction using tibialis anterior allograft tendon and additional screw fixation to reconstruct the extensor mechanism and recover knee joint range of motion to prevent a high-level functional restriction. The treatment was difficult and limited due to neglect for 9-months that led to ankylosis accompanied with nonunion of tibial fracture. Our surgical treatment using allograft tendon resulted in a very good outcome after 30 months of follow-up.