The patient, a 19-year-old male, had a history of sudden weakness of the leg and fall when walking several times. When he fell, he felt the patella deviated to one side, and then he could walk again after slowly straightening it, but there would be knee swelling, and the knee swelling subsided after about 1-2 weeks, and his daily life was not affected. However, similar situation occurred several times in bilateral knee joints. After admission, we examined the patient physically and found that the patella was more mobile to the lateral side bilaterally. Conventional frontal and lateral knee radiographs did not reveal any significant abnormalities. We also examined 30° and 60° axial patellar radiographs, which showed a significant lateral tilt and displacement of the patellae bilaterally. MRI showed lateral displacement of the patella, high patellar elevation, and a significantly higher than normal ratio of patellar tendon length to patellar long axis, and the distance between the tibial tuberosity and the intercondylar fossa of the femur measured on plain CT was normal. The diagnosis was: bilateral recurrent patellar dislocation. The patient requested surgery on one side first and observation on the other side. We performed an arthroscopic right lateral patellar release + medial tightening + inferior displacement of the tibial tuberosity, and one year postoperative follow-up, the patient’s right knee had not been dislocated again, and the knee function was completely normal. The incidence of patellar dislocation is not low in clinical practice, and it is easily overlooked because it can usually reset on its own. Not all patellar dislocations require surgical treatment, and most first-time patellar dislocations can be treated conservatively with braking, icing, and quadriceps strengthening exercises. Surgery can only be considered when there are more than 2 repeated dislocations, combined with osteochondral fractures, or when there are risk factors for recurrent dislocations.