If you feel your knee suddenly giving way when you’re walking or notice swelling around your knee, you might have a locked knee. First of all, what is meant by a locked knee? A locked knee is the sensation of suddenly getting jammed or stuck in a particular position. The affected knee cannot be straightened or bent. One might need to force the knee straight or twist it in certain positions to “unlock” it, often causing more pain and swelling.
What are the symptoms of a locked knee?
A locked knee is a condition where the knee joint becomes stuck in a particular position and cannot be bent or straightened. This condition can be painful and often requires medical attention. The symptoms of a locked knee include:
- Inability to straighten the knee: The most common symptom is where the knee remains partially bent and cannot be fully straightened.
- Pain and discomfort: Experiencing pain, especially when attempting to move the knee.
- Swelling: The knee may swell due to underlying issues causing the lock, such as an injury or inflammation.
- Stiffness: The knee might feel stiff and unresponsive.
- Difficulty walking: Walking can be challenging and painful due to the inability to straighten the knee.
- The sensation of the knee giving way: A feeling that the knee may buckle or give out under weight.
- Audible clicking or popping Sounds: In some cases, there might be a clicking or popping noise when attempting to move the knee.
- Decreased range of motion: Limited ability to move the knee through its normal range of motion.
The most common causes of a locked knee include displaced meniscus tear, loose bodies, and osteochondral fragments. Sometimes, severe muscle spasms around the knee can also cause this sensation, but it is not a true “locked knee.” Oral muscle relaxants and anti-inflammatory medications can alleviate muscle spasms, resolving this pseudo ‘locked knee.’ I will discuss the three most common causes of true locked knee below.
The three most common causes of true locked knee
1. Meniscus tear
Meniscus or menisci (plural) are C-shaped fibrocartilaginous structures within the knee joint. There are two in every knee: one on the inner (or medial) side and another on the knee’s outer (or lateral) side. They act as shock absorbers and distribute stresses across the knee joint, thus protecting the cartilage that coats its surfaces. As part of the ageing process, they can be torn or damaged during a sudden awkward twisting force to the knee.
In younger individuals, these tears often accompany ligamentous injuries, such as anterior cruciate ligament tears(commonly from traumatic sporting injuries). In older individuals, degenerative types of tears are more common.
Treatment Approaches:
Non-Surgical Management: Small, isolated, undisplaced meniscus tears can often be treated without surgery. This treatment involves rest, anti-inflammatory medications in the acute phase, and physiotherapy once the pain subsides.
Surgical Treatment: Large or unstable tears, particularly those causing locking symptoms, generally require surgical intervention. Continuing physical activities with a displaced unstable meniscus tear can cause further injury to surrounding cartilage, leading to more complex problems. Surgical treatment is typically performed arthroscopically, involving small incisions and using an arthroscope and specialised tools to repair or trim the meniscus tears.
2. Loose bodies
Loose bodies commonly occur as a result of osteoarthritis. This happens when fragments of unstable cartilage get knocked off during knee movement, and they are now free-floating within the knee joint. Sometimes, the loose bodies get stuck or jammed in the knee joint’s moving interfaces, resulting in locking symptoms. Other times, they are pushed towards the back of the knee joint and might not be causing any symptoms.
Suppose they frequently come into the way of knee movement. In that case, it is best to remove them early to prevent them from eroding healthy cartilage on the knee surfaces, thus resulting in rapid deterioration of osteoarthritis.
3. Osteochondral fragments
Osteochondral fragments can arise from conditions such as Osteochondritis Dissecans or from traumatic injuries to the knee, which knocks off a cartilage fragment with its underlying bone. Osteochondritis Dissecans is a condition that usually occurs in adolescence. It is commonly believed that this is due to abnormal blood supply to the underlying bone, which results in the detachment of a fragment of bone with its attached cartilage. It is relatively uncommon, though it is certainly something that one does not want to miss or delay treatment, as this would affect the long-term outcome of this disease.
Clinical Evaluation of a Locked Knee
If you have symptoms of locking, you should seek an evaluation. Your doctor will take a history and examine your knee. Where necessary, your doctor may need to perform additional investigations to understand the cause of your locked knee. Once we have established the cause of your symptoms, we will explain the treatment plan. Where surgery is necessary, we will detail the surgical plan and the expected recovery process after surgery. Ask questions, clarify your concerns, and take time to decide.
At Hip and Knee Orthopaedics Singapore, we believe every patient deserves comprehensive and efficient care for their musculoskeletal conditions to regain mobility independence and enjoy quality time with their loved ones.
With a passion for treating hip and knee conditions, we aim to provide you with quality care by thoroughly assessing your condition and personalising your treatments to meet your needs and goals.
