Outcomes following Distal Radius Fractures with Preexisting Ulnocarpal Abutment.

 Due to the commonality of distal radius fractures (DRFs), the potential impact of ulnocarpal abutment (UA) on patient outcomes is significant, whether it developed after or prior to injury. It is, therefore, important to consider whether preexisting UA has any impact on outcomes after an acute DRF.  The aims of this study were to determine if differences were present in (1) pain at final follow-up, (2) complications, and (3) unintended operations in patients with DRFs and either without or with preexisting radiographic UA.  A single institution retrospective cohort study comparing patients treated either nonoperatively (43 patients) or operatively (473 patients) for DRFs between 5/1/2008 to 5/1/2018 was performed. Data included demographics, prior wrist pain or surgery, ulnar variance, select treatment data, and presence of pain, complication, or unintended operation by final follow-up. Statistical testing used Fisher's exact test and chi-squared test, with a significance level of 0.05.  The prevalence of preexisting UA was 14.0 and 15.6% in the nonoperatively- and operatively treated groups, respectively. In nonoperatively treated patients without or with UA, no differences in pain (37.8 vs. 33.3%,  = 1.00) or complications were seen (13.5 vs. 50.0%,  = 0.07). A higher unintended operation rate for nonoperatively treated DRFs with UA, compared with those without, UA was seen (5.4 vs. 50.0%,  = 0.01). No differences in pain, complications, or unintended operations were seen between those without and with UA in the operatively treated group.  Preexisting UA is not associated with pain, complications, or unintended operations after operative treatment of DRFs. Prospective studies further evaluating outcomes in nonoperatively treated DRFs with UA may be beneficial.