The Science of Wrist Sprains & Strains
Wrist sprains involve damage to the ligaments that connect the bones of your wrist, most commonly affecting the scapholunate ligament complex or the triangular fibrocartilage complex (TFCC). These structures are crucial for maintaining proper carpal bone alignment and allowing coordinated wrist movement. The scapholunate interosseous ligament is particularly vulnerable to injury during falls on an outstretched hand or rotational movements under load. When this ligament is damaged, it can lead to abnormal movement patterns between the scaphoid and lunate bones, potentially causing long-term instability if not properly managed. TFCC injuries affect the complex of ligaments and cartilage on the pinky side of your wrist. This structure acts as a shock absorber and stabilizer for the distal radioulnar joint, allowing smooth rotation of your forearm while maintaining wrist stability. The healing potential of wrist ligaments varies significantly depending on their blood supply. Some areas have excellent healing capacity, while others, particularly the central portions of certain ligaments, have limited blood flow and may heal slowly or incompletely without proper treatment.
Contributing Factors
Your wrist functions as a complex joint system where eight small carpal bones must work together to provide both stability and mobility. The scapholunate ligament acts as a critical link that maintains the relationship between the scaphoid and lunate during all wrist movements.
During normal wrist extension, the scaphoid tends to flex while the lunate extends, creating a complex motion that requires intact ligamentous restraints. When the scapholunate ligament is injured, this coordinated movement is disrupted, leading to altered mechanics and potential for progressive instability.
The dart throwing motion (DTM) represents a path of movement where the wrist moves from radial extension to ulnar flexion, following the natural alignment of the carpal bones. This movement pattern places less stress on the scapholunate interval and is often used therapeutically in rehabilitation programs.
TFCC injuries affect the biomechanics of forearm rotation and ulnar-sided wrist stability. The complex must maintain proper relationship between the radius, ulna, and carpal bones during activities that involve gripping combined with rotation, such as using a screwdriver or opening jars.