Knee locking is a sore condition that occurs if the knee is extended to a certain angle. When the knee joint is extended, it is limited to 10-30 degrees to prevent pain in which the individual could not achieve full normal extension. If extended beyond the limited angle, it results to intense intractable knee pain. The usual cause of knee locking is a congenital defect, meniscus tear or osteoarthritis.
Knee locking is triggered by inflammation of the synovial membrane, ligament tear, cartilage damage or fractures in the tibia, patella or fibula. As a compact joint, the space inside is thin and limited.
What are the indications?
- Intense pain during extension
- Limited knee movement
- The knee is tender and painful during palpation
- The knee is fixed in a position, often at a 45-degree angle
- Inability to straighten the leg
- Grinding or rubbing sounds
Usual causes of knee locking
- Meniscus tear
- Fractured fibula or tibia at the knee
- Presence of cartilage or bone fragments within the joint
- Osteoarthritis causes intense pain due to limited extension of the knee
- Complications after a knee surgery
- Injuries to the knee ligaments
- Knee joint inflammation
- Patellar dislocation
- Osteochondritis dissecans causes wearing out of the cartilage which allows the bony fragments to dislodge which limits movement of the joint and cause intense pain along with knee locking.
- Medio-patellar plica tear
If the muscles or bones are misaligned due to a muscle strain or injury, it can also lead to knee locking. In either case, the knee becomes stiff and frozen which is accompanied by intense pain. When dealing with knee locking, it is vital to determine the cause of the initial symptoms.