There are different types of joints in the body, all of which allow for some degree of movement. Without joints, the body would be inflexible since the bones are rigid structures. Joints are the site where two bones meet and are able to move (articulate) by the action of muscles attached to the bone. Some joints are more flexible than others. The degree of mobility also depends on the type of articulation – gliding, hinge, ball and socket.
The two main types of movable joints in the body are :
- Cartilaginous joints where flexible cartilage connects two bones. The joint is slightly movable like the cartilaginous joints of the vertebrae.
- Synovial joints where two bones are separated by a joint space. The ends of each bone in the joint are lined by flexible cartilage and a synovial membrane secretes fluid into the joint space for lubrication. The knee joint is a typical example of a synovial joint.
In order for a joint to be flexible there needs to be space between the ends of the bone as in a synovial joint. Alternatively cartilage can occupy the space between the bones, like in a cartilaginous joint, and since this material is elastic it can be manipulated to some extent to allow for a small degree of flexibility.
What is joint stiffness?
Joint stiffness, commonly referred to as tight joints, is where the movement of a body part is reduced or impeded at the joint. It is not always due to the joint itself and can sometimes be associated with the muscles or tendons which move the opposing bones or the ligaments around the joint. However, the majority of cases of joint stiffness are due to joint problems.
Stiffness of the joints may be a result of :
- Excessive fluid in the joint space
- Crystals within the joint
- Damage or degeneration of the articular cartilage lining the ends of joints in a synovial joint
- Hardening or degeneration of the cartilage in cartilaginous joints
- Thickening or stiffening of the joint lining or capsule
Causes of Joint Stiffness
Some of the causes of joint stiffness are due to age-related changes or wear and tear. Majority of the cases, however, especially in younger people are associated with some underlying problem of the joint and its structures. The surrounding tissue like the muscles and bones may also cause joint stiffness. Sometimes systemic factors, like infections, may present with joint stiffness largely due to immune reactions.
Arthritis is inflammation of a joint and is the most common cause of joint stiffness. It can be acute or chronic. Spondylitis is an inflammation of the cartilage in cartilaginous joints like the vertebrae. Types and causes of arthritis includes :
- Osteoarthritis which is the degeneration of the cartilage over the parts of the bone involved in the joint (articular cartilage). It is often associated with long term wear and tear of the cartilage with reduced regenerative capacity of the cartilage. Osteoarthritis is the most common type of arthritis mainly seen in the elderly.
- Rheumatoid arthritis is inflammation of the joint lining caused by the immune system attacking these tissues (autoimmune disorder). The small joints of the hands and feet are more commonly affected. The exact cause is unknown but it appears to be linked to genetic factors and may be triggered by certain environmental factors or infections.
- Gout, or more correctly gouty arthritis, is an accumulation of uric acid crystals in the joint space. It presents with painful swelling and redness of the joint, mainly of the big toe. Gout arises when the uric acid levels in the blood are significantly elevated (hyperuricemia).
- Pseudogout is similar to gout but is instead caused by an accumulation of calcium pyrophosphate crystals.
- Septic arthritis is an infection within the joint most commonly caused by bacteria. The immune reaction coupled with the bacterial toxins can damage the joint lining within a short period of time. It is therefore considered to be the most serious form of arthritis warranting emergency medical attention.
- Reactive arthritis is joint inflammation associated with an infection an a site other than the joint itself. It is a result of an immune response triggered by a bacterial infection that then leads to pronounced joint inflammation. Reactive arthritis is also known as Reiter’s syndrome.
Other joint conditions that may also contribute to stiffness includes :
- Arthrosis is the wearing down of the cartilage that precedes osteoarthritis.
- Hemarthrosis is an accumulation of blood in the joint space.
- Dislocation where the bone slips out of its normal alignment in the joint.
Muscle and Bones
Diseases of the muscles and bones may also cause joint stiffness even when the joint itself is not affected. Many of these conditions may not directly impair joint mobility but rather reduce flexibility of a body part due to pain. These conditions may include :
- Osteomyelitis which is an infection of the bone.
- Bone cancer which is a malignant tumor of the bone.
- Fractures are a break in the bone.
- Stress fractures are small cracks in the bone.
- Tendonitis which is stretching and inflammation of the connective tissue bands that attach muscle to bone.
- Muscle spasm where the muscle is contracted at certain points and is stiff.
- Sprain which is stretching of the ligament that supports a joint or muscles.
There are various other causes of joint stiffness which may not be due to a disease of the joint, muscle or bone. Causes include :
- Infections like measles, mumps and the seasonal flu (influenza)
- Bursitis which is inflammation of the fluid filled pouches that reduce friction between different tissues.
- Systemic lupus erythematosus (SLE) which is an autoimmune disease where the immune system attacks tissues throughout the body.
- Medication side effects.
- Leukemia which is a type of cancer of the bone marrow or blood cells formed in the marrow.
Joint stiffness is a symptom of disorders of the joint, muscle and bone, although it can be seen with other conditions as mentioned above. Often joint stiffness occurs on its own with no other prominent symptoms. It can sometimes be the first symptom that appears with other features developing later. Two other common symptoms that often accompany joint stiffness is joint pain (arthralgia) and swollen joints. Redness and heat of the skin over the joint or around it indicates an inflammatory process, most likely arthritis.
Stiffness of the joints tends to ease with movement although this may cause the joint pain and swelling to worsen in some cases. The range of motion of the body part is often restricted and this may be described as tightness of the affected area. In some cases there may be a full range of motion but pain increases and there is difficulty and slowness in achieving the full range of motion.
Treatment of Joint Stiffness
There is no specific treatment for joint stiffness on its own. It largely depends on the underlying cause and the treatment can vary significantly even among the different types of arthritis. Supportive measures like a joint brace/guard may help to ease joint pain and stiffness associated with pain upon movement.