A stiff knee is a common physical complaint describing a restriction in the joint’s normal movement or range of motion. This limitation often makes it difficult to fully bend or straighten the leg, and while it may be accompanied by pain, the sensation of stiffness itself is a feeling of tightness or resistance. It is a symptom that can arise suddenly after an injury or develop gradually over many years, indicating a wide range of underlying issues. Understanding the nature of this restriction is the first step toward finding appropriate relief.
Understanding the Sensation of Stiffness
Knee stiffness is experienced differently depending on its origin, frequently categorized as either mechanical or inflammatory. Mechanical stiffness is characterized by a physical obstruction or restriction in the joint and is often worse after periods of activity, improving slightly with rest. This sensation feels like the joint is blocked or physically unable to reach full extension or flexion.
Inflammatory stiffness tends to be most noticeable after extended periods of rest or upon waking, sometimes referred to as “gelling.” This morning stiffness can last for thirty minutes or more, gradually improving as the person begins to move. The inflammatory process involves swelling and warmth, which restricts movement and causes the surrounding tissues to feel tight.
A loss of flexibility limits the ability to perform everyday actions like climbing stairs or crouching down. Sometimes, stiffness is accompanied by a grinding or clicking sensation, known as crepitus, which indicates roughened joint surfaces. Recognizing these distinct patterns is important because the timing and sensation of stiffness often point to the underlying cause.
Primary Underlying Causes of Knee Stiffness
The origins of knee stiffness often relate to degenerative changes, acute trauma, or mechanical interference. Degenerative arthritis is the most frequent cause, with Osteoarthritis (OA) occurring as the cartilage cushioning the joint wears down over time. This causes the bones to rub together, leading to stiffness that worsens with activity and often includes the formation of bony growths called spurs.
Inflammatory arthritis, such as Rheumatoid Arthritis (RA), is an autoimmune disease where the body attacks the synovial membrane lining the joint. This causes the membrane to swell, resulting in joint pain and the prolonged morning stiffness characteristic of inflammatory conditions. A past injury can also lead to post-traumatic arthritis years later, as the initial damage causes instability and accelerated wear on the joint surfaces.
Acute injuries and trauma are immediate sources of stiffness, often due to internal swelling (hemarthrosis) from damaged tissues. A torn ligament, such as the anterior cruciate ligament (ACL), or a sprain causes fluid to leak into the joint cavity, immediately restricting motion. Similarly, damage to the meniscus, the C-shaped cartilage that acts as a shock absorber, can cause stiffness and may lead to “locking” if a piece of torn cartilage physically impedes movement.
Mechanical issues can also cause chronic restriction. Arthrofibrosis, sometimes called stiff knee syndrome, is the excessive formation of scar tissue inside the joint, often occurring after major surgeries like a knee replacement. Conditions like tendinitis or bursitis, which are inflammations of the tendons or the fluid-filled sacs surrounding the joint, can lead to temporary stiffness due to localized inflammation and swelling.
Immediate Steps for Self-Management
For stiffness resulting from minor injury or overuse, several self-care techniques can help reduce discomfort and restore motion. The R.I.C.E. protocol—Rest, Ice, Compression, and Elevation—is the initial approach for managing acute symptoms. Resting the joint prevents further irritation, and applying an ice pack for 15 to 20 minutes several times a day helps reduce swelling and pain.
Wrapping the knee with an elastic bandage provides compression to minimize fluid accumulation, and elevating the leg above the heart level encourages fluid drainage. Over-the-counter (OTC) nonsteroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen or naproxen, can be used temporarily to reduce pain and inflammation. Gentle, non-weight-bearing range-of-motion exercises, like simple leg slides, are also beneficial by keeping the joint lubricated without causing excessive stress.
When to Seek Professional Evaluation
While self-management is appropriate for minor stiffness, certain symptoms indicate the need for immediate medical assessment. The inability to bear weight on the affected leg or a severe, sudden onset of pain requires prompt attention. Other urgent warning signs include visible deformity, fever, and noticeable redness or warmth around the knee, which could signal a serious infection.
If the knee locks up, feels unstable, or gives way during movement, it suggests a mechanical issue, such as a significant ligament tear or a displaced meniscus fragment. For chronic stiffness, a doctor’s evaluation involves a physical examination, followed by imaging tests. X-rays assess bone structure and cartilage loss, while an MRI views soft tissues like ligaments and menisci.
Professional treatment for persistent stiffness ranges from formal physical therapy, which employs tailored exercises to improve strength and range of motion, to advanced interventions. Joint injections of corticosteroids or hyaluronic acid can reduce inflammation and provide temporary cushioning. In cases of severe mechanical obstruction or advanced joint damage, surgical options like arthroscopy or joint replacement may be considered to restore full function.