Purpose: The purpose of this study was to determine the impact of an ulnar styloid fracture (USF) associated with a nonsurgically or surgically treated distal radius fracture (DRF) in adult Patients under 65 years of age.

Method: This was a cohort study involving 170 DRF patients aged 18 to 64 years old that presented to a single tertiary care center from 2004 to 2008. At initial presentation, three, six, 12 and 24 months follow up, patients were asked to complete a standardized pain and disability self-report measure, Patient Rated Wrist Evaluation (PRWE). All participants had posterior-anterior and lateral wrist radiographs performed at initial presentation and at each visit. Radiographs were reviewed at initial presentation, post treatment and at final follow up for DRF alignment as well as USF information. USFs were classified by size into tip, middle and base.

Results: There were 170 DRF patients with two patients having bilateral injuries giving a total of 172 DRFs. Age ranged from 20 to 64 years old with a mean age of 50. There were 113 females and 57 males. Eighty-four of the DRFs were not associated with an USF and 88 were. Of these 88, 42 were tip, 18 were middle and 28 were base USFs. Thirty-two of these USFs (36%) were united at final follow up. One-hundred and one patients were treated nonoperatively and 69 treated operatively for their DRFs. The PRWE scores of DRF patients with an associated USF of any size was significantly better than those without an associated USF only at 24 month follow up (10 vs. 23, p=0.04). Patients with an USF in the middle or at the base had better PRWE scores at both 12 and 24 months (17 vs. 23, p=0.05 at 12 months & 10 vs. 20, p=0.01 at 24 months). An ulnar head fracture had no influence on PRWE scores. There was no difference in PRWE scores between united and nonunited ulnar styloid fractures at all follow up time points.

Conclusion: We found that an USF was associated with better PRWE scores at 24 months and that the larger USFs, middle and base fractures, were associated with better scores at as early as 12 months. A fall onto the outstretched hand includes a component of force transmission through the ulnar side of the wrist. Without a bony ulnar styloid injury, we hypothesize that this force is transmitted through the soft tissues, creating an associated occult ligamentous, TFCC or other undetected soft tissue injuries resulting in higher pain and disability among those without a fracture. This hypothesis will require further attention in future studies. Union of the USFs also did not show an effect on outcome.