Heterotopic ossification around the patellar tendon is known to be extremely rare. A 42-year-old man had a transverse fracture of the left patella. Open reduction and tension band wiring were performed. At four weeks, plain radiographs showed an extensive ossification around the patellar tendon and the patient presented limitation of flexion and pain in kneeling position. We just encouraged active and passive ranges of motion exercises and performed one manipulation under anesthesia. At the final follow-up (10 months post-operatively), he was able to flex his knee by 140 degrees. We present a case of heterotopic ossification around the patellar tendon with limitation of knee flexion that was successfully treated with nonoperative treatment.