Objective/Hypothesis: Carpal dislocations are easily missed on initial presentation, as x-rays can appear unremarkable. It is thought that perilunate injuries in general make up around 10% to 19% of all wrist sprains; however, no incidence or prevalence studies have been undertaken. We aimed to establish the incidence of carpal instability between 1 and 2 years post acute wrist injury as the result of a fall using established clinical and radiological measures and secondarily, attempt to estimate its relationship with functional impairment. Materials and Methods: This incidence study used multiple overlapping sources to ascertain all patients presenting to a major urban hospital with wrist pain following fall onto outstretched hand between 1and 2 years post injury. Carpal instability was defined by blinded radiological evaluations and provocative clinical tests, including Scaphoid Shift (Watson) test, ballottement, and midcarpal shift test. Wrist-related pain and disability were measured using the patient-rated wrist and hand evaluation. Results: Fifty participants (28 male, 22 female) with a mean age of 47.8 years met inclusion criteria. We found a cumulative incidence of 40% of carpal instability within the second year post injury, based on clinical testing. X-ray evaluations were inconsistent with clinical findings. There were no significant correlations between clinically confirmed carpal instability and presence of fracture at the time of injury, pain, function, age, sex, high energy trauma, or sick days from work. Conclusions: This study found a higher than anticipated cumulative incidence of carpal instability in the second year post injury. Patients should be advised to monitor symptoms in the year post injury and seek a review if symptoms of pain, clicking, or clunking arise.
