Pathophysiology
The TFCC has a substantial risk for injury and degeneration because of its anatomic complexity and multiple functions.
Application of an extension-pronation force to an axial-load wrist, such as in a fall on an outstretched hand, causes most of the traumatic injuries of the TFCC. Dorsal rotation injury, such as when a drill binds and rotates the wrist instead of the bit, can also cause traumatic injuries. Injury may also occur from a distraction force applied to the volar forearm or wrist. Finally tears of the TFCC are frequently found by patients with distal radius fractures.
Perforations and defects in the TFCC are not all traumatic. There is an age related correlation with lesions in the TFCC, but many of these defects are asymptomatic. These lesions common occur by patients with positive ulnar variance.
Chronic and excessive loading through the ulnocarpal joint, causes degenerative TFCC tears. These tears are a component of ulnar impaction syndrome. Even though natural degeneration of the ulnocarpal joint is very common, it is important to recognize. In cadavaric examinations, 30% to 70% of the cases had TFCC perforations and chondromalacia of the ulnar head, lunate and triquetrum. Cases with ulnar-negative variance had fewer degenerative changes.
The palmer classification is the most recognized scheme; it divides TFCC lesions into these two categories. This classification provides an accurate anatomic description of tears, it does not guide treatment or indicate prognosis.
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