X-Ray Transparency Interpositions After Reduction of Traumatic Dislocations of the Hip in Children

Abstract

Traumatic dislocations of the hip are much less frequent in children than in adults. If some complications are well known (avascular necrosis of the femoral head, recurrent dislocation), the lateralization of the head by x-ray transparency interposition is less appreciated. We report 4 cases of x-ray transparency interposition in 15 reductions of incomplete traumatic dislocation of the hip. These 4 dislocations were posterior in non-pathological hips, three on the left side and one on the right. Our reductions have been easy and the hips remained stable. However, the post-reduction roentgenogram shows the same unusual enlarged joint space corresponding to the lateralization of the femoral head. Four arthrotomies were performed, tracing a cartilaginous fragment free or fixed to the articular capsule into the femoral joint. We have found a concentric reduction of the hip in 4 cases and enlargement from 1 to 3 mm of the joint space of the hip. After several years, articular function of the four hips is normal, nevertheless, they have shown a coxa valga with a femoral elongation to 10 mm, a coxa magna with an articular space wider than 1 mm, 2 very good concentric reductions of the hip. The lateralization of the head after reduction had to be detected as soon as the first radiographic control because it can cause immediate instability or arthrosis of the hip. Because of the cartilaginous or capsular composition and the size of the interposition, an arthrotomy is performed in front of a radiological enlarging of the space joint, or a loss of parallelism of osteochondral acetabulum bone. Computerized tomography and MRI can reveal the nature, the place of the included fragment, as well as the surgical approach. An arthrogram is not absolutely indispensible. Surgical exploration should avoid degenerative arthrosis after a lateralisation left untreated.

Traumatic Hip Dislocation in Childhood

“…This change may have been due to postinjury hyperemia and synovitis 16 or possibly a secondary direct effect of trauma. 1,8,14 We found a statistical correlation with age and coxa magna development and noted that it occurred in younger children (P , 0.05).…”

“…It seems to us that in children, a postreduction CT scan of the hip should be reserved for cases where the joint space remains widened to allow visualization of bone lesions and/or interposed osteochondral or capsular elements. 2,8 We feel that surgical exploration is required whenever there is residual postreduction joint space asymmetry.…”

Incongruent reduction following post-traumatic hip dislocations as an indicator of intra-articular loose bodies: A prospective study of 117 dislocations

“…It plays a role in the analysis of an incongruent hip in which both plain radiographs and CT images demonstrate unexplained joint widening, in nondisplaced fractures that are not apparent on axial CT scans, and in patients with incarcerated fragments or interposed soft tissues 127. However, the ‘gold standard’ remains direct visualization of the joint space 2122…”

Transepiphyseal fracture of the femoral neck with dislocation of the femoral head and fracture of the posterior column of the acetabulum in a child

“…3,5,7,14,20 Imperfect reduction is associated with early degenerative change. 21 In younger children there is a possibility of recurrent dislocation with detachment of the posterior capsule. [22][23][24] Associated acetabular fractures are very rare and occur with high-energy injuries in older children, usually only involving the posterior wall of the acetabulum.…”