The Effect of Scaphoid Morphology After Surgical Fixation of Scaphoid Nonunions on Long-term Functional Outcomes and Scaphoid Union Rates

Abstract Scaphoid nonunion can progress to wrist pain, stiffness and an established pattern of wrist arthritis. The effect of scaphoid malunion on clinical outcomes is largely unknown. In this study, the effect of scaphoid morphology on union rates and clinical outcomes is explored using a prospectively collected database of surgeries. The primary aim of the study is to understand the effect of initial post-surgical scaphoid morphology on union. The secondary aim examines the effect of final scaphoid morphology on long-term functional outcomes among patients that underwent surgical fixation for scaphoid nonunion and ultimately went on to union. 84 participants were included in this study. 74 (88.1%) nonunions went to union, and 10 (11.9%) remained persistent nonunions after surgery. After nonunion surgery, the initial post-operative height-to-length (H/L) ratio was predictive of scaphoid union. For every 0.1 increase in H/L ratio, odds of union were reduced by 53.7%. Of the patients who progressed to union, there was a significant relationship (p=0.019) between initial post-operative H/L ratio and final DASH scores. It was found that there was a 35.9% increase in DASH score for every 0.1 increase in H/L ratio. Similarly, there was a significant relationship (p=0.013) between final post-operative H/L ratio and final DASH scores where an increase of 0.l in H/L ratio translated to a 33.5% increase in DASH. The authors propose that the restoration of initial post-operative H/L ratio can predict odds of union after surgical fixation of an established scaphoid nonunion. Improved morphology at union as measured by H/L ratio also demonstrated improved functional outcomes, such as DASH score.