7.6: Diseases and Injuries of Joints
- Page ID
- 63417
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- Classify sprains according to severity
- Describe what happens in a joint dislocation
Arthritis
Arthritis is a common disorder of synovial joints that involves inflammation of the joint. This often results in significant joint pain, along with swelling, stiffness, and reduced joint mobility. There are more than 100 different forms of arthritis. Arthritis may arise from aging, damage to the articular cartilage, autoimmune diseases, bacterial or viral infections, or unknown (probably genetic) causes.
Osteoarthritis
The most common type of arthritis is osteoarthritis, which is associated with aging and “wear and tear” of the articular cartilage (Figure \(\PageIndex{1}\)) . Risk factors that may lead to osteoarthritis later in life include injury to a joint; jobs that involve physical labor; sports with running, twisting, or throwing actions; and being overweight. These factors put stress on the articular cartilage that covers the surfaces of bones at synovial joints, causing the cartilage to gradually become thinner. As the articular cartilage layer wears down, more pressure is placed on the bones. The joint responds by increasing production of the lubricating synovial fluid, but this can lead to swelling of the joint cavity, causing pain and joint stiffness as the articular capsule is stretched. The bone tissue underlying the damaged articular cartilage also responds by thickening, producing irregularities and causing the articulating surface of the bone to become rough or bumpy. Joint movement then results in pain and inflammation.
In its early stages, symptoms of osteoarthritis may be reduced by mild activity that “warms up” the joint, but the symptoms may worsen following exercise. In individuals with more advanced osteoarthritis, the affected joints can become more painful and therefore are difficult to use effectively, resulting in increased immobility. There is no cure for osteoarthritis, but several treatments can help alleviate the pain. Treatments may include lifestyle changes, such as weight loss and low-impact exercise, and over-the-counter or prescription medications that help to alleviate the pain and inflammation. For severe cases, joint replacement surgery (arthroplasty) may be required (Figure \(\PageIndex{2}\)).
Joint replacement is a very invasive procedure, so other treatments are always tried before surgery. However arthroplasty can provide relief from chronic pain and can enhance mobility within a few months following the surgery. This type of surgery involves replacing the articular surfaces of the bones with prostheses (artificial components). For example, in hip arthroplasty, the worn or damaged parts of the hip joint, including the head and neck of the femur and the acetabulum of the pelvis, are removed and replaced with artificial joint components. The replacement head for the femur consists of a rounded ball attached to the end of a shaft that is inserted inside the diaphysis of the femur. The acetabulum of the pelvis is reshaped and a replacement socket is fitted into its place. The parts, which are always built in advance of the surgery, are sometimes custom made to produce the best possible fit for a patient.
Gout
Gout is a form of arthritis that results from the deposition of uric acid crystals within a body joint (Figure \(\PageIndex{3}\)). Usually only one or a few joints are affected, such as the big toe, knee, or ankle. The attack may only last a few days, but may return to the same or another joint. Gout occurs when the body makes too much uric acid or the kidneys do not properly excrete it. A diet with excessive fructose has been implicated in raising the chances of a susceptible individual developing gout.
Autoimmune Diseases
Autoimmune diseases, including rheumatoid arthritis, scleroderma, or systemic lupus erythematosus, produce arthritis because the immune system of the body attacks the body joints. In rheumatoid arthritis, the joint capsule and synovial membrane become inflamed. As the disease progresses, the articular cartilage is severely damaged or destroyed, resulting in joint deformation, loss of movement, and severe disability. The most commonly involved joints are the hands, feet, and cervical spine, with corresponding joints on both sides of the body usually affected, though not always to the same extent. Rheumatoid arthritis is also associated with lung fibrosis, vasculitis (inflammation of blood vessels), coronary heart disease, and premature mortality. With no known cure, treatments are aimed at alleviating symptoms. Exercise, anti-inflammatory and pain medications, various specific disease-modifying anti-rheumatic drugs, or surgery are used to treat rheumatoid arthritis.
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Sprains
A sprain is an acute injury of a ligament that is often caused by a sudden or severe movement forcing the joint to exceed its normal range of motion. The collagen fibers in a ligament have a small amount of elasticity - they can stretch by approximately 4% of their length. Tension applied by stretching or twisting that exceeds this elasticity limit will case the collagen fibers to tear. Sprains can occur at any joint, but they most commonly occur in the ankle, knee, or wrist. The majority of sprains are mild, causing minor swelling and bruising that can be resolved with conservative treatment, typically summarized as RICE: rest, ice, compression, and elevation. The most severe sprains involve complete tears, ruptures, or fractures, often leading to joint instability, severe pain, and decreased functional ability. These sprains require prolonged immobilization and sometimes surgery and/or physical therapy. Classification of sprains is based on the severity of damage to the ligament:
- First degree sprain (mild) – There is minor stretching and structural damage to the ligament on the microscopic level, leading to mild swelling and bruising. Patients typically present without joint instability or decreased range of motion of the joint. Return to normal function can be expected from 4 days to 4 weeks.
- Second degree sprain (moderate) – There is a partial tear of the affected ligament. Patients typically experience moderate swelling, tenderness, bruising and some instability of the joint. There may be some difficulty bearing weight on the affected joint resulting from the increased range of motion and the pain. Return to normal function depends on severity and can range from 4 weeks to 4 months.
- Third degree sprain (severe) – There is a complete rupture or tear of the ligament, sometimes avulsing (tearing off) a piece of bone (Figure \(\PageIndex{5}\)). Patients typically experience severe joint instability, pain, bruising, swelling, and inability to apply weight to the joint. However, in a minority of cases the patient may not experience any pain after the tear because the damage also severed the nerve endings that would normally send the pain signals to the brain. Return to normal function depends on severity and whether surgical repair is necessary, but the typical range is 3 to 6 months.
Knee Joint
Injuries to the knee are common. Since this joint is primarily supported by muscles and ligaments, injuries to any of these structures will result in pain or knee instability. Injury to the posterior cruciate ligament occurs when the knee is flexed and the tibia is driven posteriorly, such as falling and landing on the tibial tuberosity or hitting the tibia on the dashboard when not wearing a seatbelt during an automobile accident. More commonly, injuries occur when forces are applied to the extended knee, particularly when the foot is planted and unable to move. Anterior cruciate ligament injuries can result with a forceful blow to the anterior knee, producing hyperextension, or when a runner makes a quick change of direction that produces both twisting and hyperextension of the knee (Figure \(\PageIndex{6}\)).
Figure \(\PageIndex{6}\): MRI of Knee Ligaments. Ligaments appear dark black on an MRI because of their lack of water. In image A both the ACL and PCL (arrows) are normal and appear as thick black bands; in image B the PCL is normal but the torn ACL appears as a fuzzy, variable grey area. (Image Credits: "MRI of Knee Ligaments" by Jennifer Lange are licensed under CC BY-NC-SA 4.0, based on originals A: "MRI Normal ACL and PCL": Marios G Lykissas, George I Mataliotakis, Nikolaos Paschos, Christos Panovrakos, Alexandros E Beris and Christos D Papageorgiou, CC BY-SA 2.0, via Wikimedia Commons; B: MRI ACL tear: Case courtesy of Dr Ali Alsmair, Radiopaedia.org. From the case rID: 95927)
A worse combination of injuries can occur with a hit to the lateral side of the extended knee (Figure \(\PageIndex{7}\)). A moderate blow to the lateral knee will cause the medial side of the joint to open, resulting in stretching or damage to the tibial collateral ligament. Because the medial meniscus is attached to the tibial collateral ligament, a stronger blow can tear the ligament and also damage the medial meniscus. This is one reason that the medial meniscus is 20 times more likely to be injured than the lateral meniscus. A powerful blow to the lateral knee produces a “terrible triad” injury, in which there is a sequential injury to the tibial collateral ligament, medial meniscus, and anterior cruciate ligament.
Arthroscopic surgery has greatly improved the surgical treatment of knee injuries and reduced subsequent recovery times. This procedure involves a small incision and the insertion into the joint of an arthroscope, a pencil-thin instrument that allows for visualization of the joint interior. Small surgical instruments are also inserted via additional incisions. These tools allow a surgeon to remove or repair a torn meniscus or to reconstruct a ruptured cruciate ligament. The current method for anterior cruciate ligament replacement involves using a portion of the patellar ligament. Holes are drilled into the cruciate ligament attachment points on the tibia and femur, and the patellar ligament graft, with small areas of attached bone still intact at each end, is inserted into these holes. The bone-to-bone sites at each end of the graft heal rapidly and strongly, thus enabling a rapid recovery.
Dislocation
A dislocation is the complete separation of the bones that form a joint, usually caused by trauma such as a car accident or a fall. In a partial dislocation, called a subluxation, the bones in the joint shift out of position but the articular surfaces remain in partial alignment. The shifting of the bones can also cause damage to the surrounding joint structures such as ligaments, the joint capsule, or the labrum as well as nearby muscles, blood vessels, or nerves. The most commonly dislocated joint is the shoulder, accounting for about 50% of injuries. Other commonly dislocated joints are the fingers, toes, patella, elbow, and hip, with the frequency of each varying by country. Joint dislocation results in pain, swelling, and, sometimes, bruising. Because moving the injured joint is so painful, some people are unwilling or unable to move it and will attempt to hold the bones to keep them immobile.
A. Anterior Shoulder Dislocation
B. Shoulder Dislocation Clinical Appearance
C. Lateral Patella Dislocation
D. Finger Dislocation, 2nd DigitA dislocated joint usually can be successfully be manipulated (through pulling, twisting, etc.) into its normal position only by a trained medical professional. This procedure is called a reduction, as the displacement is reduced by bringing the bones back into normal alignment. Trying to reduce a joint without any training could substantially worsen the injury. Manipulating the bones back into position can be a very painful process, therefore people are given pain relievers, sedatives, and/or an anesthetic before the procedure, depending on the severity and location of the injury. Following reduction of the joint, a PRICE regimen is recommended: protection (immobilization), rest, ice, compression (pressure), and elevation.
Review Questions
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Critical Thinking Questions
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Glossary
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Contributors and Attributions
OpenStax Anatomy & Physiology (CC BY 4.0). Access for free at https://openstax.org/books/anatomy-and-physiology