The wrist comprises many bones, joints, nerves, ligaments, tendons and blood vessels. The "outer side" of the wrist is the thumb or radial side, and mainly constitutes the radius bone, the scaphoid and lunate carpal bones, the first metacarpal bone, and the radial and median nerves. All of these structures can be injured--usually from trauma--and cause outer wrist pain. The main causes of outer wrist pain are ligament damage, nerve entrapment, De Quervain's tenosynovitis, bone fractures, arthritis, avascular necrosis and ganglions.
Ligament Damage
The most common injury to the outer wrist involves ligament damage. Usually, the lateral ligaments are mildly sprained, or stretched, and heal quickly. Ligament tears are more serious and can cause instability of the lunate carpal bone, or partial dislocation of the distal radius. Gamekeeper's thumb is a chronic sprain at the inside base of the thumb. Common causes include athletic trauma, such as gymnastics, martial arts and football; falling with an outstretched hand; and recurring wrist movements.
Nerve Entrapment
Nerves become entrapped in the wrist because of lack of space and inflammation or scar tissue from repetitive trauma. Carpal tunnel syndrome is chronic inflammation of the tunnel formed by the carpal bones, which primarily entraps and compresses the median nerve. Laterally, an entrapped median nerve causes pain, weakness and tingling in the thumb and outer palm. Wartenberg syndrome is compression of the outer radial nerve and affects the thumb as well. Wrist inflammation occurs from trauma or repetitive motions like typing, writing and painting.
De Quervain's Tenosynovitis
De Quervain's tenosynovitis is inflammation of the tendon sheaths of the abductor pollicis longus and the extensor pollicis brevis tendons, which causes pain and swelling in the outer wrist, and reduces movement of the thumb. Causes include repetitive thumb movements such as video gaming, athletic trauma and accidental falls.
Bone Fractures
In general, fractures of the wrist are the most common fracture up until the age of 75. In the outer wrist, the scaphoid, lunate, first metacarpal and the distal end of the radius bones are usually broken. Wrist fractures are caused by trauma--especially contact sports like ice hockey and boxing--but also motor vehicle accidents and falling with an outstretched hand. Osteoporosis can lead to lateral wrist fractures more readily.
Arthritis
Osteoarthritis--the "wear and tear" type--and inflammatory arthritis such as rheumatoid and psoriatic are fairly common in the wrist. Osteoarthritis is caused by frequent sprains and strains, overuse, unhealed fractures and joint dislocations, which can lead to achy pain and grinding with lateral wrist movement. Rheumatoid arthritis is an auto-immune disorder and usually affects both wrists simultaneously.
Avascular Necrosis
Avascular necrosis can be a complication of severe trauma and cause pain if the blood supply to an area is cut off. In the outside wrist, the scaphoid and the lunate bones are most susceptible to avascular necrosis, especially following fractures.
Ganglions
Ganglions are little fluid-filled cysts within tendon sheaths that can occur over the outside wrist due to fluid blockage. Ganglions are benign, but they can grow to the size of a pea over time. They create pain by putting pressure on tendons, ligaments and nerves.
References
- "Radial Side Hand and Wrist Pain: Diagnois and Treatment of Common Problems"; Journal of Chinese Clinical Medicine; Ran Schwarzkopf, M.D. et al; July 2007
- Medline Plus: Wrist Pain
- "Clinical Sports Medicine"; Peter Brukner et al; 2005
