From the Guidelines
Knee locking is most commonly caused by meniscus tears, particularly "bucket handle" tears, as well as other conditions such as loose bodies, anterior cruciate ligament (ACL) tears, patellofemoral issues, and osteoarthritis with bone spurs. When considering the cause of knee locking, it's essential to evaluate the patient's symptoms and signs, including pain, swelling, locking, catching, popping, giving way, tenderness, effusion, loss of motion, and crepitus 1. The diagnosis of knee locking can be approached with radiographs, including AP, lateral, sunrise/Merchant, and tunnel views, as an option for patients with knee symptoms and/or signs 1. Some key points to consider when evaluating knee locking include:
- Meniscus tears are a common cause of knee locking, particularly "bucket handle" tears
- Loose bodies, such as fragments of cartilage or bone, can also cause knee locking
- ACL tears, patellofemoral issues, and osteoarthritis with bone spurs are other potential causes of knee locking
- Initial treatment typically includes rest, ice, compression, and elevation (RICE protocol), along with over-the-counter pain medications like ibuprofen or acetaminophen
- Avoid activities that worsen symptoms, and consider medical intervention, including physical therapy or possibly surgery, depending on the underlying cause 1. It's crucial to prioritize the patient's morbidity, mortality, and quality of life when determining the best course of treatment for knee locking. Given the available evidence, the most appropriate recommendation for the cause of knee locking is to consider meniscus tears, loose bodies, ACL tears, patellofemoral issues, and osteoarthritis with bone spurs as potential causes, and to approach diagnosis and treatment with a comprehensive evaluation of the patient's symptoms and signs 1.
From the Research
Causes of Knee Locking
The causes of knee locking can be attributed to various mechanical or functional factors. Some of the most common causes include:
- Meniscal injuries, such as meniscal tears, which are the most frequent arthroscopic finding in locked knees 2, 3, 4
- Loose bodies in the knee joint, which can be caused by trauma or degeneration 3, 5, 4
- Rupture of the anterior cruciate ligament (ACL) 3
- Gouty tophus, which is a rare cause of knee locking 2
- Meniscal subluxation, which is a controversial and rarely reported cause of knee locking 6
- Cysts of the cruciate ligaments and focal pigmented villonodular synovitis, which are less common causes of knee locking 4
Diagnosis and Treatment
The diagnosis of knee locking is typically made using magnetic resonance imaging (MRI), which is considered the gold standard in diagnostic imaging 3, 5, 4, 6. Knee arthroscopy is also commonly used to diagnose and treat knee locking, and is considered the gold standard in management 3, 5, 6. The treatment of knee locking depends on the underlying cause, and may involve surgical or conservative management 3, 5, 6.