Although the wrist appears simple from the outside, the inside of the joint is a complex interconnection of ligament, bones, cartilage, and tendons. When someone sustains impact to their wrist, any one or a combination of those structures can get damaged, resulting in pain and loss of function.
The most common mechanism of injury is a fall onto an outstretched hand, causing the wrist to be forcibly bent backwards (hyperextended). When this occurs, the ligaments (direct bone to bone connections) are stretched and sometimes torn. Similarly, the small bones of the base of the hand (the carpal bones) can actually be broken by the leverage of the force from the hand and forearm.
There are two types of cartilage in the wrist. The articular cartilage is the smooth, shiny covering on the bone that allows two bones to touch with minimal friction. Fibrocartilage is a fibrous, thicker material that sits between certain bones acting like a cushion or bumper. Either type of cartilage can be scuffed or torn when compression and shearing occur in the wrist with impact.
Tendons connect muscle to bone, allowing the muscles to move and control our joints. In a fall, the muscles and tendons tighten by reflex to brace for the impact. Under this kind of load, the tendons can be strained and sometimes torn. This is especially true in areas where the tendons make a change of direction (common near the wrist).
The severity of a wrist sprain is very difficult to assess just by inspection alone. The degree of a pain, swelling and bruising may not be very different between a mild sprain where soft tissues have been merely stretched versus a severe injury where ligaments are completely torn or carpal bones may be broken. If a wrist injury looks suspicious at all, prompt evaluation by a qualified health care professional is recommended. A careful examination of the wrist, often combined with imaging studies such as x-ray and MRI (magnetic resonance imaging), will sort out which structures have been injured and how severely. The initial treatment, regardless of severity, is typically immobilization with a splint, elevation to reduce swelling and icing for comfort.
Ultimately, an evaluation by an experienced hand surgeon will lead to a specific treatment plan. Many sprains can be treated with immobilization alone, often in some type of removable brace. For some injuries; especially if serious soft tissue or bone damage has been identified, surgery may be considered. The goal of surgery is usually to repair, remove or replace the damaged structures. These procedures are typically done safely in an outpatient setting.