A new definition of wrist sprain necessary after findings in a prospective MRI study.

INTRODUCTION

Wrist injuries with negative X-rays are diagnosed as acute wrist sprains. The prognosis is usually good, but some patients suffer from long-lasting pain and reduced wrist function, probably due to missed diagnosis followed by inappropriate treatment. The aim of this study was to investigate acute wrist sprains with MRI to detect the pathoanatomy of the injury.

PATIENTS AND

METHODS

This prospective magnetic resonance imaging (MRI) study included patients between 18 and 49 years, who attended the Accident and Emergency Department (A&E) Bergen, Norway, after sustaining an acute wrist trauma within the previous week. Initial X-rays of the wrist were normal. MRI was done within a median of 1 day (range 0-31 days) after the trauma, 80% within 4 days. The study period lasted from 5 November 2009 to 4 November 2010.

RESULTS

A total of 155 acute MRIs were done, out of which 30 were completely normal. Patients with positive MRI had a median of two (range 0-8) pathological findings. We found 54 fractures and 56 bone bruises, mostly located to the radius followed by the scaphoid, the triquetrum, the capitate and the lunate. There were 73 soft-tissue injuries, which included 15 injuries to the triangular fibrocartilage complex (TFCC) and five scapho-lunate (SL) ligament lesions.

CONCLUSIONS

Wrist sprain is an inaccurate diagnosis. In four out of five patients with normal X-rays, MRI identified pathological findings and a large variety of injuries in different structures. We suggest that wrist sprain should be defined as "occult partial or complete soft tissue (ligament, tendon, muscle) or bony injury in relation to a trauma with negative X-ray". The MRI findings led to a more differentiated treatment in more than a third of the patients. We recommend that MRI should be considered as a part of an early investigation, especially when the wrist pain does not settle within the first couple of weeks.