Angular malalignment as cause of limitation of forearm rotation: an analysis of prospectively collected data of both-bone forearm fractures in children.

Although limitation of pronation/supination following both-bone forearm fractures in children is often attributed to an angular malunion, no clinical study has compared pronation/supination and angular malalignment of the same child by analysis of prospectively collected clinical data.The purpose of this trial is to explore whether limitation of pronation/supination can be predicted by the degree of angular malalignment in children who sustained a both-bone forearm fracture.In four Dutch hospitals, children aged ≤16 years with a both-bone forearm fracture were prospectively followed up consecutive children for 6-9 months. At the final follow-up, pronation/supination and angular malunion on radiographs were determined.Between January 2006 and August 2010, a total of 410 children were prospectively followed up, of which 393 children were included for analysis in this study. The mean age of the children was 8.0 (±3.5) years, of which 63% were male and 40% fractured their dominant arm. The mean time to final examination was 219 (±51) days. Children with a metaphyseal both-bone fracture of the distal forearm with an angular malalignment of ≤15° had a 9-13% chance of developing a clinically relevant limitation (i.e., <50° of pronation and/or supination), while children with an angular malalignment of ≥16° had a 60% chance. Children with diaphyseal both-bone forearm fractures with ≤5° of angular malalignment had a 13% chance of developing a clinically relevant limitation, which showed no significant increase with a further increase of angular malalignment.Children who sustained a both-bone forearm fracture localised in the distal metaphysis have a higher chance of developing a clinically relevant limitation of forearm rotation in case of a more severe angular malalignment, while children with a diaphyseal both-bone forearm fracture had a moderate chance of limitation, irrespective of the severity of the angular malalignment.