Ball and Socket Joints: Anatomy, Location, and Function (2024)

This article will discuss different types of joints, how a ball and socket joint moves, and examples of ball and socket joints throughout the body.

Anatomy

A ball and socket joint is a synovial joint, which means it allows for smooth movements between bones. The end of one bone within the joint is spherical, forming the ball, while the end of the other bone within the joint contains a rounded depression, forming the socket. The ball slides, rolls, and spins within the socket to allow movement of the joint in multiple directions. Because ball and socket joints move through three or more planes of movement, they are the most mobile joints in the body.

Examples of ball and socket joints include:

• The shoulder joint, which allows for 8 different movements (flexion, extension, abduction, adduction, internal rotation, external rotation, horizontal abduction, and horizontal adduction) that combine to move the arm
• The hip joint, which allows for 6 different movements (flexion, extension, abduction, adduction, internal rotation, and external rotation) that combine to move the leg

Because the ball and socket joint of the shoulder is the most mobile joint of the body, it is also the most unstable and at risk of dislocating.

Function

Ball and socket joints allow for movement of the arms and legs in multiple directions essential for all daily functions. This includes activities of daily living like bathing, getting dressed, and eating, and everyday movements like walking and standing up and sitting down.

Associated Conditions

Osteoarthritis and inflammatory forms of arthritis can affect any joint, but commonly affect the ball and socket joints of the shoulders and hips, causing joint pain and stiffness.

Autoimmune inflammatory forms of arthritis, including rheumatoid arthritis and psoriatic arthritis, that cause the body to attack its own joints can also affect the shoulders and hips, although the knees and fingers are more commonly affected. Symptoms of these types of arthritis include redness, swelling, stiffness, and pain.

Other conditions that affect ball and socket joints include injuries to the cartilage within the joints or the labrum, a ring of tougher cartilage within the joints that helps hold the ball within the socket. Trauma, repeated overuse, or joint dislocation can damage the labrum in either the shoulder or hip, causing pain, catching, clicking, locking, and instability.

Other specific conditions affect the shoulder and hip individually.

Shoulder Conditions

The ball of the shoulder socket is stabilized and held in place by the rotator cuff tendons that surround the shoulder. Tears to one or more of the rotator cuff tendons can result in pain and instability of the shoulder, which can lead to shoulder dislocation or subluxation.

When the shoulder is not moved enough, oftentimes after injury or surgery, afrozen shoulder (adhesive capsulitis) can develop. With frozen shoulder, the joint capsule of the shoulder joint becomes very stiff, which significantly limits shoulder range of motion and causes pain.

Hip Conditions

Hip dysplasia is a condition where the hip bones do not fully form during development. This results in a shallow hip socket that incompletely stabilizes the hip joint, resulting in frequent hip dislocation and associated pain.

Avascular necrosis can also affect the hip joint and occurs when the blood supply to the hip is cut off, causing the bone cells in the hip to die. Avascular necrosis often causes pain and hip range of motion limitations. Many factors can contribute to the development of avascular necrosis, including injury, extended use of corticosteroid medication, chemotherapy or radiation treatment to a nearby area, autoimmune conditions, and infections.

Rehabilitation

Conditions that affect ball and socket joints often cause inflammation and swelling, resulting in pain and limited joint movement. After injuries or during flare-ups of inflammatory conditions, limiting active movement and resting the affected ball and socket joint is beneficial at first to reduce increased stress and pain to the joint. Applying ice and using pain-relieving medications like non-steroidal anti-inflammatory drugs (NSAIDs) can also help reduce pain.

Once your pain and swelling start to subside, physical therapy can be used to help rehabilitate your affected ball and socket joints. Your physical therapist will provide you with stretches and exercises to help improve the range of motion of your joints and strength of surrounding muscles to support your joints.

If you experience ball and socket joint pain from an autoimmune condition like rheumatoid arthritis or psoriatic arthritis, biologic medication to decrease your body’s autoimmune activity is often administered through infusions delivered every several weeks or months. Cortisone injections may also be used to decrease inflammation within your painful joints.

For certain conditions that do not improve with medication and physical therapy, surgery may be needed. Severe forms of osteoarthritis that cause significant pain may require a total shoulder replacement or a total hip replacement, while full rotator cuff tears often need surgical repair to reattach the torn tendons. Labral tears in either the shoulder or hip may also need surgery if physical therapy does not improve symptoms. If hip pain and dislocation is significant with hip dysplasia, a surgical procedure called periacetabular osteotomy may be performed to realign the hip joint.

Summary

Ball and socket joints are a type of synovial joint that moves throughout three or more planes of motion into multiple directions. Ball and socket joints are found in the shoulders and hips and control movement essential for all daily functions. Injuries, osteoarthritis, and autoimmune conditions can all affect ball and socket joints while rest, medication, ice, and physical therapy can be used to help reduce pain and improve your strength and range of motion. For significant conditions including shoulder and hip osteoarthritis, rotator cuff tears, labral tears, and hip dysplasia, surgery may be needed to treat symptoms.

A Word from Verywell

If you notice difficulty moving your shoulders or hips, make sure to speak with your healthcare provider. Joint stiffness is often a sign of arthritis, and all forms of arthritis tend to worsen over time without treatment. Regular movement and exercise are key for reducing joint stiffness to keep your ball and socket joints moving properly to support your daily activities.