forearm rotation occurs around an axis connecting the center of the radial head and the fovea of the distal ulna .
various treatments for malunion have been reported , but the optimal method for reduction remains controversial .
we planned this study to determine numerical values indicative of healing treatment during deformation of the forearm .
we therefore investigated cases in which corrective osteotomy was performed for malunion without dislocation of the elbow or wrist .
our hypothesis was that increased differences between the axes of forearm and proximal radius would be associated with increased deterioration of forearm rotational motion .
data from patients with corrective osteotomies for malunited forearm fractures without dislocation of the elbow or wrist were reviewed retrospectively .
patient demographics were reviewed , including age , sex , and interval between injury and surgery .
mean interval between initial injury and surgery was 21 months ( range , 347 months ) .
mean duration of follow - up was 12 months ( range , 622 months ) .
this retrospective study included eight cases ( 6 men , 2 women ) , and mean patient age was 15 years ( range , 1021 years ) .
fracture type was radioulnar shaft fracture in five cases and radial shaft fracture in three cases .
initial treatment of forearm fractures comprised conservative treatment in five cases and operative treatment in three cases . pre- and postoperative ranges of motion were obtained from clinical charts .
we performed corrective osteotomy of the radius alone in five cases , ulna alone in one case , and both radius and ulna in two cases .
intraoperatively , we attempted to restore the normal shape of both bones according to intraoperative fluoroscopic images and anteroposterior and lateral radiographs .
we evaluated plain radiographic images using medical image analysis software ( rapideye ; toshiba medical systems , tochigi , japan ) .
anteroposterior and lateral radiographs of the forearm were obtained using the same position of forearm rotation ( in the neutral position , if possible ) , with the elbow in 90 of flexion , and the wrist in neutral alignment .
two lines were drawn : the axis of the proximal radial head ; and the forearm axis .
the angle between these two lines was then measured on both lateral and anteroposterior radiographs ( fig .
if the tuberosity of the radius and styloid were not on opposite sides of the bone , we determined malrotation by plain radiography . with the ulna ,
the coronoid process of the ulna and the ulnar styloid process are normally on opposing sides , so we used this relationship to assess malrotation of the ulna .
the longitudinal ( rotational ) axis of the forearm runs from the center of the radial head proximally to the fovea of the distal ulna .
the axis of the proximal radius runs between the center of the radial head and the radial neck .
proximal radial tilt angle (  ) represents the angle between the rotational axis of the forearm and the axis of the proximal radius .
differences in forearm rotation and in radiological assessments were analyzed using the mann - whitney u test .
we evaluated plain radiographic images using medical image analysis software ( rapideye ; toshiba medical systems , tochigi , japan ) .
anteroposterior and lateral radiographs of the forearm were obtained using the same position of forearm rotation ( in the neutral position , if possible ) , with the elbow in 90 of flexion , and the wrist in neutral alignment .
two lines were drawn : the axis of the proximal radial head ; and the forearm axis .
the angle between these two lines was then measured on both lateral and anteroposterior radiographs ( fig .
if the tuberosity of the radius and styloid were not on opposite sides of the bone , we determined malrotation by plain radiography . with the ulna ,
the coronoid process of the ulna and the ulnar styloid process are normally on opposing sides , so we used this relationship to assess malrotation of the ulna .
the longitudinal ( rotational ) axis of the forearm runs from the center of the radial head proximally to the fovea of the distal ulna .
the axis of the proximal radius runs between the center of the radial head and the radial neck .
proximal radial tilt angle (  ) represents the angle between the rotational axis of the forearm and the axis of the proximal radius .
differences in forearm rotation and in radiological assessments were analyzed using the mann - whitney u test .
mean forearm rotation increased from 81 ( range , 0135 ) preoperatively to 138 ( range , 108175 ) postoperatively .
mean proximal radial tilt angle improved from 14 to 9.3 , compared to 3.3 on the normal side .
postoperative rotation correlated with proximal radial tilt angle , and severe malunion affected the range of forearm rotation ( fig .
2 ) . three patients were considered to show radial malrotation and no patients displayed ulnar malrotation .
mean rotation in malrotation cases was 128  17.2 , compared to 145  26.9 in the remaining cases .
the forearm is composed of the radius and ulna , which are linked by the interosseous membrane and intercalated between the elbow and wrist . the forearm rotation axis runs through the center of the radial head to the ulnar head , and radial motion around the ulna results in forearm rotation .
angular deformity of the forearm affects forearm rotation , so the treatment for malunion of the forearm should be provided by treating the radius and ulna as bones of a joint .
although corrective osteotomy can achieve good rotation within 1 year after injury , the factors contributing to clinical results remain unclear and no reports have clarified how deformity of the axis of rotational motion affects forearm rotation .
the acceptable range of deformity at initial treatment for fracture remains contentious , particularly in pediatric cases , due to good remodeling ability .
our series included skeletally immature cases , but a previous report showed that in diaphyseal fractures , the distal radial epiphyseal plate realigned well only in children under 10 years of age , so our results appear reasonable .
some recent papers have reported three - dimensional computed tomography ( 3dct ) and computer - assisted osteotomy for malunion .
indeed , we think that malunion of the forearm should be treated in 3d , but we investigated the indicators for corrective osteotomy only on plain radiographs in consideration of radiation exposure and usability .
we tried to reduce malrotation , and only three cases showed malunion and the degrees of deformity were mild .
differences in each parameter were also relatively small and the small sample size could have limited the statistical power of the analyses .
bones , ligaments and soft tissues would affect rotation , but the rigid body element must provide the primary effects on forearm rotation .
we evaluated the results of corrective osteotomy for forearm fracture malunion using plain radiography . to improve the range of rotation
we think the angle between the axis of rotation of the forearm and the axis of the proximal radius offers a useful indicator for corrective osteotomy .
 abstractforearm rotation occurs around an axis connecting the center of the radial head and the fovea of the distal ulna . 
 the purpose of the present study was to demonstrate the usefulness of the difference between forearm and proximal radial axis in the treatment of malunited forearm fractures . 
 we reviewed the results of eight corrective osteotomies for malunited fractures of the forearm without dislocations of the wrist or elbow . 
 subjects were 6 men and 2 women ( mean age , 15 years ; range , 1021 years ) . 
 corrective osteotomy was performed at the fracture site . 
 preoperatively and at final follow - up , the arc of forearm rotation was recorded and anteroposterior and lateral x - rays were taken . 
 proximal radius tilt was defined as the angle between the rotational axis of the forearm and the axis of the proximal radius . 
 corrective osteotomy improved proximal radius tilt in all cases . 
 three patients were considered to have malrotation . 
 postoperative rotational arc correlated with proximal radial tilt ( r = 0.83 ) . 
 no significant difference in rotational arc was evident between malunited cases and the remaining cases . to improve forearm rotation , corrective osteotomy 
 should be planned to minimize proximal radius tilt.key words : forearm fracture , corrective osteotomy , malunion , axis 
INTRODUCTION
MATERIALS AND METHODS
Radiological assessment
Statistical analysis
RESULTS
DISCUSSION