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The left femur (proximal fracture) is at increased risk of internal malrotation and the right femur (distal fracture) is at increased risk of external malrotation.
46%
1156/2505
The left femur (proximal fracture) is at increased risk of external malrotation and the right femur (distal fracture) is at increased risk of internal malrotation.
33%
825/2505
Malrotation does not depend on fracture location, but whether the nail is placed antegrade or retrograde.
5%
137/2505
Both femora are at increased risk of internal malrotation.
13%
318/2505
Malrotation does not depend on fracture location, but whether the nail uses a piriformis entry point or a trochanteric entry point.
2%
44/2505
Select Answer to see Preferred Response
In proximal femoral fractures, the distal fragment (femoral shaft) will be relatively internally rotated. In distal femoral fractures, the distal fragment will be relatively externally rotated. The direction of femoral malrotation depends on the pull of attached muscles. In PROXIMAL fractures, the proximal fragment is externally rotated by the iliopsoas, short external rotators and abductors. This leads to relative internal rotation of the distal fragment (femoral shaft), leading to INTERNAL malrotation. In DISTAL fractures, the proximal fragment (femoral shaft) is pulled medially by the adductors, while the distal fragment is pulled into external rotation by the lateral gastrocnemius and plantaris, leading to EXTERNAL malrotation. Lindsey et al. reviewed malrotation following femoral shaft nailing and found that malrotation was present in up to 27.6% of all femoral shaft fractures managed this way. Risk was highest with pure transverse fractures (OTA 32-A3), and Winquist III and IV fractures (OTA 32-C). Using a fracture table increases risk of internal malrotation, and supine positioning with a bump (without fracture table) increases risk of external malrotation. Ricci et al. reviewed nailing of femoral shaft fractures. They recommend the following to obtain correct rotation: (1) using alignment of the anterior superior iliac spine, patella and second toe, (2) fluoroscopic evaluation of cortical widths, key fragments or femoral anteversion, (3) checking both legs for symmetry before leaving the operating room. They also state that "The direction of femoral malrotation is based on which attached muscles are involved. For example, proximal femur fractures tend toward net internal rotation of the femoral shaft secondary to the pull of the iliopsoas muscle, short external rotators, and glutei on the proximal femur. The relative external rotation of the proximal femur results in internal rotation of the distal segment. Conversely, external malrotation can occur in distal femoral fractures secondary to the pull of the adductor muscles on the proximal fragment and the pull of the plantaris and lateral gastrocnemius muscles on the distal fragment." Illustration A shows how muscle attachments affect fracture deformity and predispose to malrotation. Incorrect Answers Answers 2, 4: Proximal fractures tend to develop internal malrotation, while distal fractures develop external malrotation. Answer 3: There is no known difference in malrotation between retrograde vs antegrade nail placement. Answer 5: There is no known difference in malrotation between piriformis vs trochanteric nail starting points.
3.1
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