Some knee joints have instability factors such as medial collateral ligament rupture or cruciate ligament rupture, but the entire duration is very short and the clinical manifestations may not be obvious. In the case of cruciate ligament rupture, the knee feels like it is stuck when walking, especially when going up and down stairs, and the whole knee joint needs to be shaken to move. Medial collateral ligament ruptures sometimes feel particularly lax during a knee walking sprain and have very pronounced pain on the medial side. Long-term knee instability can lead to wear and tear of the meniscus and articular cartilage inside the knee joint and further traumatic arthritis, when there is pain going up and down stairs or pain that is more pronounced when playing badminton or table tennis. The clinical signs include rupture of the cruciate ligament or the medial and lateral collateral ligaments, which are commonly associated with a positive drawer test of the cruciate ligament or a positive inversion stress test of the knee.