Cumulative incidence of carpal instability 12-24 months after fall onto outstretched hand

Descriptive Epidemiological Study.

Ligament tears between carpal bones are easily missed on initial presentation, but can have potentially debilitating effects on the patient if they progress to an instability. They are usually the result of a fall onto an outstretched hand with the wrist in hyperextension. Current incidence of carpal instability after these falls is unknown.

Using established clinical and radiological measures, we sought to establish the cumulative incidence of carpal instability in people who have fallen onto an outstretched hand in the second year after injury. We also sought to describe its relationship with functional impairment.

We used emergency department records of an inner-urban tertiary hospital to contact all patients who presented with wrist pain following fall onto outstretched hand who were between one and two years after injury. Carpal instability was defined by blinded radiological evaluations and provocative clinical tests, including Scaphoid Shift (Watson's) test, Ballottement, and mid-carpal shift test. Wrist-related pain and disability was measured using the Patient-Rated Wrist and Hand Evaluation.

Of the 279 potentially eligible cases, only 146 were contactable, and fifty (28 male, 22 female; mean age of 48 years) attended for assessment. We found a cumulative incidence of 44% of carpal instability within the second year after injury. Of these, 12 (24%) cases had scapho-lunate instability, 12 (24%) had luno-triquetral instability and 7 (14%) had mid-carpal instability. There were no significant correlations between clinically confirmed carpal instability and pain, function, or work participation.

This study found a higher than anticipated cumulative incidence of carpal instability in the second year after injury, which may reflect volunteer bias. Patients should be advised to monitor symptoms in the year after injury and seek a review if symptoms of pain, clicking or clunking arise.

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