Abstract
Background Scaphoid malunion is rarely reported. Previous literature has attributed loss of
carpal height and degenerative changes to scaphoid malunion, but the percentage of
asymptomatic malunions remains unknown.
Purpose The authors of this study aim to define predictors of malunion and outcomes associated
with scaphoid malunion.
Methods Institutional board review was obtained prior to evaluating medical records of patients
18 years and older who were treated for scaphoid fractures and/or nonunion between
2000 and 2020. The following data were collected for each patient: age, gender, fracture
location, surgical technique, time to union, and whether malunion resulted. Malunion
was defined using a lateral intrascaphoid angle (LISA) >45 degrees and height-to-length
ratio (HLR) >60. Pain scores, range of motion (ROM), and secondary surgery were also
evaluated.
Results Overall, 355 scaphoid injuries, including 196 acute fractures and 159 nonunions,
were evaluated in this analysis. Of these, 55 scaphoids (15%) met the definition of
malunion. Of these patients, 23% were female. The mean age at the time of injury was
29 years. Nonunion cases were more likely than acute cases to be associated with malunion.
Proximal pole fractures were more likely to associated with malunion than waist fractures.
When controlling for nonunion and fracture location, malunited scaphoids were not
associated with any significant difference in pain score, ROM, or secondary surgery,
compared with nonmalunion cases. A total of 10 patients (3.3%) without malunion and
2 patients (3.6%) with malunion went on to a secondary surgery. Final extension/flexion
was 67/67 degrees and 56/59 degrees in nonmalunion and malunion groups, respectively,
but these differences were not significant.
Conclusion Compared with scaphoid injuries that do not result in malunion, scaphoid injuries
that heal into malunion have similar outcomes. While scaphoid malunion in a single
case or series may be associated with poor outcomes, this study suggests that scaphoid
malunions do not have worse functional outcomes.
Level of Evidence This is a Level IV study.
Keywords
scaphoid - malunion - function - pain - union - surgery - fracture - SNAC
