Review Question - QID 8974

This patient has neutral version on the operative side and 6 degrees of anteversion on the normal side, therefore no further procedures are required.

Rotational malalignment or torsional deformity is expressed as a difference in femoral version between the injured and uninjured leg. It can be measured clinically, radiograpically, and most accurately by CT scan. CT scan is the method of choice because of its reliability and reproducibility. The incidence of rotational malalignment may be as high 30% in some fracture patterns. Fracture comminution is a risk for rotational malalignment as it alters the ability to obtain a cortical read. Differences between sides of <10 degrees are considered variations of normal while differences of >15 degrees are considered true torsional deformities and likely require de-rotation.

Jaarsma et al. detail how to obtain a rotational profile of the femur. Rotational alignment is determined by the angle between a line tangential to the femoral condyles and a line drawn through the axis of the femoral neck. The difference in angle between the fractured and unaffected side determines the rotational alignment. A decrease in anteversion of the femoral neck of the fractured side implies increased external rotation and an increase denotes increased internal rotation of the distal fragment.

Koerner et al. measured 328 normal femora and found that there were no statistically significant differences in mean version between African American, white, and Hispanic patients for males or females. They found retroversion to be common in white males, African American males, and all females. They conclude that this may have implications in proper alignment restoration after IM nailing of femur fractures.

Gardner et al. performed a cadeveric study and found that freehand distal interlocking may be a substantial cause of rotational deformity. They found that freehand insertion may cause a 7 degree change in alignment. They saw that when inserting the drill freehand, drill/nail contact caused a visible shift of the fracture site. They conclude that the use of computer navigation systems may improve this issue.

Figure A demonstrates a subtrochanteric femur fracture, while Figure B demonstrates the same fracture, stabilized with a piriformis entry nail. Figures C-F demonstrate axial CT cuts to determine femoral version. Figure C demonstrates hip anteversion of 18 degrees, while figure D reveals knee external rotation of 18 degrees. This side exhibits neutral rotation (18-18). Figure E demonstrates hip anteversion of 9.2 degrees while figure F demonstrates knee external rotation of 3.2 degrees. This side exhibits 6 degrees of anteversion (9.2-3.2).

Incorrect Answers:
Answers 1, 2, 4, 5 do not have the correct combination of version and need for further procedures.