From the Guidelines
A knee making a clunking sound is most likely due to structural issues within the joint, such as patellofemoral syndrome, meniscus tears, loose bodies, or osteoarthritis, which can cause abnormal movement between joint surfaces, tendons, or ligaments snapping over bony prominences, or air bubbles popping in the synovial fluid. The sound can occur when there's mechanical catching or grinding between joint surfaces. According to a recent study 1, dynamic US can be used to evaluate causes of snapping knee, including patellar clunk, snapping popliteus, and snapping related to component/liner malposition.
Possible Causes
- Patellofemoral syndrome: where the kneecap doesn't track properly in its groove
- Meniscus tears: creating mechanical catching
- Loose bodies: like cartilage fragments floating in the joint
- Osteoarthritis: where roughened cartilage surfaces grind together
- Aseptic loosening or osteolysis: as discussed in a study 1, which can lead to component loosening and may require revision surgery
Evaluation and Treatment
While occasional clicking or popping without pain is usually harmless, persistent clunking accompanied by pain, swelling, or instability warrants medical evaluation. Treatment depends on the underlying cause and may include:
- Rest
- Physical therapy to strengthen supporting muscles
- Anti-inflammatory medications like ibuprofen (400-800mg three times daily with food)
- Surgical intervention for structural repairs, as discussed in a study 1, which highlights the importance of evaluating available bone stock in preparation for revision surgery.
Importance of Medical Evaluation
It is crucial to evaluate the knee to determine the underlying cause of the clunking sound, as some causes may require prompt medical attention to prevent further damage or complications. A study 1 discusses the utility of using dynamic US for the workup of patellar clunk syndrome, highlighting the importance of proper diagnosis and treatment. Therefore, if a knee is making a clunking sound, it is essential to seek medical evaluation to determine the cause and appropriate treatment.
From the Research
Causes of Knee Clunking Sound
- A clunking sound in the knee can be caused by various factors, including patellar clunk or crepitation after primary total knee arthroplasty 2
- Meniscal tears may also contribute to abnormal sounds in the knee, although the exact relationship between meniscal tears and clunking sounds is not well-established 3, 4, 5
- Other factors such as patellar retention, lateral reticular release, and previous surgery may increase the risk of patellar clunk or crepitation 2
Risk Factors for Patellar Clunk or Crepitation
- Intraoperative variables such as patellar retention and lateral reticular release can increase the risk of patellar clunk or crepitation 2
- Clinical variables such as previous surgery can also contribute to the risk of patellar clunk or crepitation 2
- Radiographic measurements such as increased anterior tibial offset, increased joint line changes, and increased postoperative knee flexion angle can also be associated with patellar clunk or crepitation 2
Management of Knee Clunking Sound
- The management of knee clunking sound depends on the underlying cause, and may involve surgical or non-surgical approaches 6, 2
- In cases of patellar clunk or crepitation after primary total knee arthroplasty, modifiable factors such as patellar retention and lateral reticular release should be considered and addressed to limit the risk of patellar clunk or crepitation 2
- For meniscal tears, meniscal repair has been shown to have better long-term outcomes and is therefore recommended for all tears, especially for young patients with acute traumatic lesions 3, 4, 5