Knee replacement surgery alleviates pain and restores mobility for many. After surgery, it is common to notice sounds like clicking. While these sounds can be concerning, they are often a normal part of the joint’s function and adjustment.
The Mechanics of a Knee Replacement
A total knee replacement involves replacing damaged bone and cartilage with artificial components. These components typically include a metal alloy cap for the end of the thigh bone (femur), a metal alloy platform for the top of the shin bone (tibia), and a strong plastic insert, usually made of polyethylene, that sits on the tibial component. The undersurface of the kneecap (patella) may also be replaced with a plastic component.
These prosthetic parts recreate the knee’s natural movement. The metal femoral component articulates with the polyethylene insert on the tibial component, allowing the knee to bend and straighten smoothly. Materials like cobalt-chromium or titanium alloys for metal parts and polyethylene for plastic are chosen for durability.
Common Reasons for Clicking
Clicking in a knee replacement can stem from several factors. A common reason is the sound of metal and plastic components interacting as they move. This is often a normal mechanical sensation, as implant surfaces produce sound more readily than natural cartilage.
Soft tissue impingement can also cause clicking. This occurs when ligaments, tendons, or scar tissue around the knee rub against the implant or bone. Scar tissue can sometimes catch or snap over the prosthetic components.
Issues with the kneecap (patella) tracking smoothly can lead to clicking. If the kneecap does not move correctly, it might rub against other implant parts. Component loosening or wear of the polyethylene insert can also contribute to noises. Rarely, gas bubbles forming and bursting within the joint fluid can produce a popping sound.
When Clicking Requires Attention
While many instances of knee replacement clicking are harmless, certain accompanying symptoms suggest the need for medical evaluation. A sudden onset of clicking after a period when the knee was quiet can be a warning sign. Clicking that is accompanied by pain, swelling, or warmth around the joint warrants immediate attention.
Additional concerning symptoms include a feeling of instability or the knee “giving way” when bearing weight. Clicking that progressively becomes louder or more frequent, or that limits the knee’s range of motion or function, should also be discussed with a healthcare provider. If clicking occurs after a fall or injury, it is important to seek medical advice.
Addressing and Managing Clicking
For clicking that is not accompanied by pain or other concerning symptoms, observation is often the initial approach. Many benign sounds may diminish over time as the knee adjusts and surrounding tissues strengthen. Physical therapy can be beneficial, focusing on strengthening the muscles around the knee to improve joint alignment and stability.
Activity modification, such as adjusting movements that exacerbate clicking, can help manage the sensation. If inflammation or pain is present, medication may reduce these symptoms. Surgical intervention is a last resort for problematic clicking, reserved for severe pain, instability, or confirmed issues like component loosening, wear, or soft tissue impingement unresponsive to other treatments. This may involve arthroscopic surgery to remove scar tissue or revision surgery to address implant issues.