Joints

The joints in our hands are made up of cartilage surfaces that cap the bones.  Cartilage is a smooth surface that allows for gliding. When cartilage is healthy, there is a cushioning effect of the cartilage that absorbs and evens out the forces across the joint.  Our joints typically have a capsule of tough, but flexible, fibrous tissue that helps hold the joints together and an inner lining of synovium.  The synovium has multiple functions including to help provide fluid for lubrication of the joint.  The tough fibrous tissue is often what is injured when you have a sprain of a joint.

When discussing hand joints, we refer to the palmar or volar surface (the palm side), the dorsal surface (the back of the hand), the radial side (toward the thumb), and the ulnar side (toward the little finger).

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Finger Joints

Thumb

Interphalangeal Joint (IP)
The thumb digit has only two phalanges (bones) so it only has one joint. The thumb interphalangeal (IP) joint is similar to the distal interphalangeal (DIP) joint in the fingers. The IP joint in thumb is located at the tip of the finger just before the fingernail starts. The terminal extensor tendon in the thumb comes from the extensor pollicis longus muscle. The radial and ulnar collateral ligaments are important to provide stability of the fingertip during pinching.

Metacarpophalangeal Joint (MP)
The MP joint is where the hand bone, called the metacarpal, meets the finger bones, called the phalanges. A single finger bone is called a phalanx. MP joints are important for both power grip and pinch activities; they are where the fingers move in relation to the hand. The MP joint primarily allows you to bend and extend the thumb. The ulnar collateral ligament of the thumb MP joint is important to stabilize the thumb during most pinch activities and is commonly injured.

Carpometacarpal Joint (CMC)
The thumb CMC joint has the most freedom of motion. The thumb metacarpal can bend and extend the thumb, move the thumb away from and toward the hand, and spin the thumb on the trapezium. Two very important ligaments are the dorsoradial and the volar beak ligaments.  The abductor pollicis longus and brevis help move the thumb away from the hand. The adductor pollicis helps move the thumb toward the hand. The thumb CMC joint is one of the most common areas in the hand and wrist to develop arthritis. Surgical treatment for arthritis of the joint often includes removal of the trapezium or resurfacing of the joint.  Common injuries to this joint include a Bennett’s fracture and a Rolando’s fracture. 

Learn about thumb arthritis.

Scaphotrapeziotrapezoid Joint (STT)

The scaphotrapeziotrapezoid joint is at the base of the thumb in the wrist. It is made up of three wrist bones, the scaphoid, the trapezium, and the trapezoid. The scaphoid rotates at this joint as you move the wrist. This joint can become arthritic. Treatment of arthritis in this joint can include removal of the scaphoid, removal of the trapezium and part of the trapezoid, or arthrodesis (also known as fusion).

Index Finger

Distal Interphalangeal Joint (DIP)
The DIP joint in the finger is located at the tip of the finger, just before the finger nail starts. Common problems at this joint include Mallet Finger, Jersey Finger, arthritis, mucous cysts, and fractures. The index finger is more likely to develop arthritis from the pinch force that occurs throughout one’s life.

Proximal Interphalangeal Joint (PIP Joint)
The PIP joint is the first joint of the finger and is located between the first two bones of the finger. The PIP joint can bend and extend the finger. It becomes stiff easily after injury.  Common injuries include sprains, fractures, dislocations, arthritis, and extensor tendon ruptures (leads to Boutonnière deformity), and hyperextension (Swan neck).

Metacarpophalangeal Joint (MCP joint)
The MP joint is where the hand bone called the metacarpal meets the finger bones called the phalanges. A single hand bone is called a phalanx. MP joints are important for both power grip and pinch activities; they are where the fingers move with respect to the hand. The MP joints allows you to bend and flex your fingers, spread your fingers, and bring the fingers together. You can spread your fingers more more easily when they are straightened rather than bent because the collateral ligaments are loose when the finger is extended. Common problems at the MCP joint include arthritis and collateral ligament injuries.

Carpometacarpal Joint (CMC Joint)
The index CMC joint has little motion; this provides a more rigid and stable radial column to the hand. Injuries and problems with this joint are uncommon. Occasionally, joint pain can be caused by a CMC boss.

Middle Finger

Distal Interphalangeal Joint (DIP Joint)

The DIP joint in the finger is located at the tip of the finger, just before the finger nail starts. Common problems at this joint include Mallet Finger, Jersey Finger, arthritis, mucous cysts, and fractures.

Proximal Interphalangeal Joint (PIP Joint)
The PIP joint is the first joint of the finger and is located between the first two bones of the finger. The PIP joint can bend and extend the finger. It becomes stiff easily after injury and has very limited side to side motion. Common injuries include sprains, fractures, dislocations, arthritis, extensor tendon ruptures (leads to Boutonnière deformity), and hyperextension (Swan neck).

Metacarpophalangeal Joint (MCP Joint)
The MP joint is where the hand bone called the metacarpal meets the finger bones called the phalanges. A single hand bone is called a phalanx. MP joints are important for both power grip and pinch activities; they are where the fingers move with respect to the hand. The MP joints allows you to bend and flex your fingers, spread your fingers, and bring the fingers together. You can spread your fingers more more easily when they are straightened rather than bent because the collateral ligaments are loose when the finger is extended.


Common problems at the MCP joint include arthritis and collateral ligament injuries. 
The middle finger MCP joint is the most common finger (it can happen to any finger) to have a radial sagittal band injury. This results in the extensor tendon snapping to the pinky side of the hand.

Carpometacarpal Joint (CMC Joint)
The middle finger CMC joint has little motion. Injuries and problems with this joint are uncommon. Occasionally, joint pain can be caused by a CMC boss.

Ring Finger

Distal Interphalangeal Joint (DIP Joint)
The DIP joint in the finger is located at the tip of the finger, just before the fingernail starts.  Common problems at this joint include Mallet Finger, Jersey Finger, arthritis, mucous cysts, and fractures.

Proximal Interphalangeal Joint (PIP Joint)
The PIP joint is the first joint of the finger and is located between the first two bones of the finger. The PIP joint can bend and extend the finger. It becomes stiff easily after injury and has very limited side to side motion. Common injuries include sprains, fractures, dislocations, arthritis, extensor tendon ruptures (leads to Boutonnière deformity), and hyperextension (Swan neck).

Metacarpophalangeal Joint (MCP Joint)
The MP joint is where the hand bone, called the metacarpal, meets the finger bones called the phalanges. A single hand bone is called a phalanx. MP joints are important for both power grip and pinch activities and are where the fingers move with respect to the hand. The MP joints allows you to bend and flex your fingers, spread your fingers, and bring the fingers together. You can spread your fingers more more easily when they are straightened rather than bent because the collateral ligaments are loose when the finger is extended. Common problems at the MCP joint includes arthritis and collateral ligament injuries.

Carpometacarpal Joint (CMC Joint)

The ring finger CMC joint has much more motion than the index or middle fingers. This permits the hand to change its shape and adapt to grasping objects of different size and shape. Because this joint is more mobile, it is more common to have a fracture or dislocation of this joint. CMC bossing does not typically occur at this joint.

Small Finger

Distal Interphalangeal Joint (DIP Joint)
The DIP joint in the finger is located at the tip of the finger just before the fingernail starts. Common problems at this joint include Mallet Finger, Jersey Finger, arthritis, mucous cysts, and fractures.

Proximal Interphalangeal Joint (PIP Joint)
The PIP joint is the first joint of the finger and is located between the first two bones of the finger. The PIP joint can bend and extend the finger. It becomes stiff easily after injury. Common injuries include sprains, fractures, dislocations, arthritis, extensor tendon ruptures (leads to Boutonnière deformity), and hyperextension (Swan neck).

Metacarpophalangeal Joint (MCP Joint)
The MP joint is where the hand bone called, the metacarpal, meets the finger bones called the phalanges. A single hand bone is called a phalanx. MP joints are important for both power grip and pinch activities and are where the fingers move with respect to the hand. The MP joints allows you to bend and flex your fingers, spread your fingers, and bring the fingers together. You can spread your fingers more more easily when they are straightened rather than bent because the collateral ligaments are loose when the finger is extended. Common problems at the MCP joint includes arthritis and collateral ligament injuries.

Carpometacarpal Joint (CMC Joint)

The small finger CMC joint has the most motion of any finger joint, with the exception of the thumb. This makes the hand more flexible. This permits the hand to change its shape and adapt to grasping objects of different size and shape. Because this joint is more mobile it is more common to have a fracture or dislocation, particularly when you hit a hard object. CMC bossing is a problem that does not typically occur at this joint.


Wrist Joints

Radiocarpal Joint

The radiocarpal joint consists of the radius, one of the forearm bones, and the first row of wrist bones consisting of the scaphoid, lunate, and triquetrum. There is also a fourth bone in the first row of wrist bones called the pisiform, but it does not connect to either the radius or ulna. Wrist fractures that involve the joint surface are common wrist injuries. One of the most common ligaments involved in a wrist sprain is the scapholunate ligament.

Ulnocarpal Joint

The ulnocarpal joint includes the ulna, one of the forearm bones, as well as the lunate and triquetrum. Ulnocarpal injuries are common with sprains. A broken wrist (fracture) that collapses and tilts can cause the ulna to be longer than the radius, which causes extra stress and pain, even after the fracture heals and stops hurtig. Some people who are born with, or develop, an ulna that is longer than the radius can have pain or even have ulnocarpal abutment (impaction) syndrome. A person with a shorter ulna than radius can also have a higher chance of developing Kienbock’s disease

Distal radioulnar

The distal radioulnar joint is at the wrist where the two forearm bones meet. Distal radioulnar joint instability or pain can sometimes be a challenging problem to treat.


Elbow Joints

Ulnohumeral joint

The ulnohumeral joint is formed by the coming together of the humerus and ulna bones. This joint is responsible for bending and extending the elbow.  Ulnohumeral arthritis can cause pain and make it difficult to bend and straighten the elbow. This can make it painful and difficult to the get the hand to the mouth, wash hair, or hold a phone to your ear.

Radiocapitellar

The radiocapitellar joint is formed by the coming together of the radius and the capitellum, which is a part of the humerus. Radiocapitellar problems often lead to a clicking sound and pain when rotating the elbow.

Proximal radioulnar

Pronation and supination occur at this joint, which is the act of rotating your palms to face upward and downward. Radial head fractures often disrupt the close fit between the two bones at the proximal radioulnar joint, leading to pain and loss of motion.


Shoulder Joints

Glenohumeral

The glenohumeral joint is the coming together of the upper arm bone, the humerus, and a portion of the shoulder blade called the glenoid. The glenoid is a shallow cup that connects to the humerus. The shoulder has a great deal of motion including bending and straightening, moving away from the side of the body, moving toward the body, and circumduction (a spinning type of motion). Common problems with this joint include stiffness, dislocation, labral tears, bursitis, rotator cuff tears, long head of biceps tendonitis or tears, subacromial impingement, proximal humeral fractures, and arthritis. 

Acromioclavicular (AC)

The AC joint is a smaller joint associated with the shoulder. The acromium is part of the scapula (shoulder blade) and the clavicle (also called the collarbone). The AC joint is where the scapula and clavicle come together.  There are three major ligaments, the acro-mioclavicular, coracoacromial, coracoclavicular. This joint is involved with raising and lowering the arm and moving the arm forward and backward. An AC separation is a common injury of this joint which occurs from a fall or a direct blow to the shoulder. Many shoulder separations are treated without surgery, but some may require surgery to reconstruct the coracoacromial or coracoclavicular ligaments. Osteoarthritis is also common and can be treated sometimes with surgery.  

Sternoclavicular joint (SC)

The sternoclavicular joint is the junction of the sternum (breastbone) and clavicle (collarbone). There is an articular disc of fibrocartilage within the joint. The motion of this joint permits the clavicle to move up and down and front to back. There are no tendons that attach to this joint area.  A posterior (back) SC joint dislocation can be a serious injury and puts vital structures at risk such as the heart, aorta, superior vena cava, esophagus, and trachea. Anterior (front) dislocations can also occur and are often somewhat less serious, but can cause pain and clicking.