Injuries and Conditions: The Wrist

The wrist is comprised of some of the smallest bones in the upper body and represents one of the most complex joints. Often vulnerable to injury because of its range of motion and involvement in day-to-day activities and sports, special understanding of the wrist’s anatomy and effective small bone and joint treatments and techniques is a significant part of upper extremity orthopedics.

The wrist is the narrow, flexible connection between the forearm and the hand. It has eight "carpal" bones, which are arranged in two rows of four - the proximal row sits closest to the crease of the wrist and the distal row sits closer to the fingers.

Beginning at the thumb side of the wrist, the proximal row of carpal bones consists of the scaphoid, lunate and triquetrum and connects the two bones of the forearm, the radius and the ulna, to the hand bones. The distal row of the carpal bones consists of the trapezium, trapezoid, capitate, hamate and pisiform. Contributing to the complexity of the wrist joint is the intricate network of joints created by each small carpal bone connecting to the next. The wrist is actually a joint comprised of many smaller joints.

Covering the ends of the bones at each joint and serving as a type of shock absorber facilitating movement of the joint is articular cartilage. This type of cartilage, which is thinner in the wrist joint than in other large weight-bearing joints such as the knee, provides a smooth buoyant surface that allows the joint surfaces to glide across one another without damaging the bones. Articular cartilage in the wrist covers the sides of all of the carpal bones, as well as the ends of the bones connecting from the forearm to the fingers.

The wrist joint is surrounded by a capsule, which is strengthened by the volar radiocarpal, dorsal radiocarpal, the ulnar, and the radial collateral ligaments. The synovial membrane lines the surfaces of these ligaments. The collateral ligaments are two important ligaments supporting each side of the wrist and connecting it to the forearm.

Located on the ulnar side of the wrist is the ulnar collateral ligament (UCL). This ligament originates at the ulnar styloid, the bony bump at the edge of the wrist, and provides support to a small body of cartilage called the triangular fibrocartilage complex (TFCC). The TFCC is located between the ulna and two of the carpal bones, the lunate and the triquetrum. It's function is to improve the range of motion and ease of movement within the wrist joint, while helping to cushion the area of the joint in which it is located.

Located on the thumb side of the wrist is the radial collateral ligament (RCL), which originates at the outer edge of the radius on a small bump called the radial styloid. The RCL connects at the side of the scaphoid and prevents the wrist from bending too far to the side opposing the thumb.

Located on the thumb side of the wrist is the radial collateral ligament (RCL), which originates at the outer edge of the radius on a small bump called the radial styloid. The RCL connects at the side of the scaphoid and prevents the wrist from bending too far to the side opposing the thumb.

As a result of the constant bending and straightening of daily wrist motion, the nerves traveling through the wrist sustain stress that can lead to pressure within their tunnels (Carpal Tunnel and Guyon's Canal) and result in pain, weakness and numbing in the hand.

Because of the anatomy of the wrist joint and involvement in daily tasks, sports and defense it is susceptible to a variety of conditions that can create an unstable wrist environment. Distal radius fractures and Scaphoid fractures are among the most common fractures in the upper body. If instability within the wrist joint is not addressed early enough, a degenerative environment is created - ultimately leading to arthritis.