Bone malrotation
Further research is currently being examined in this area to reduce occurrences of malrotation, including detailed computer navigation to improve visual accuracy during surgery.
[1][3] However, due to the semi-closed nature of IM, it is impossible to correct under direct vision, so there is less rotational control compared to traditional open methods such as plate fixation.
[4] Historically, bone malrotation occurred due to a lack of adequate treatment measures, where fixation methods such as traction, casting and non-locked nails provided poor torsional stability.
Currently, the utilisation of locked intramedullary nailing, has reduced the occurrence of rotational malalignment during fracture healing, yet femoral malrotation continues to remain very prevalent due to surgeon's inability to reliably restore the pre-injury alignment during operation.
For femoral or tibial malrotation, many surgeons use the patient's ankle or patella to symmetrically align them with the injured side or to the floor but this method does not consider the position of the proximal fragment and could be moved during reduction attempts.
However, while clinical assessment can indicate the direction of malrotation, it often reports inaccurate measurements of the degree of malalignment, so it is unreliable in determining the potential impacts and necessary treatment methods.
Firstly, an anteroposterior (AP) perspective which shows the degree of difference between the femoral neck and femur, and another view where the hips and knees are both flexed to a right angle, which determines antetorsion.
[5] The standard bone malrotation detection practice utilised are computed tomography scans, which are able to exactly quantify the amount of rotational malalignment.
Another advantage of CT scans is that patient positioning does not impact the measurement accuracy of femoral torsion, which is unlike radiographs and ultrasounds.
However, inaccurate measurements of malrotation can still occur in CT scans, but are mostly related difficulty in drawing clear and accurate lines along the femoral neck within the image.
[2] Malrotation of the femur in the setting of a mid-shaft fracture has an impact on the axis of the entire leg, which shifts the centre of force in the knee away from its neutral position.
This can cause pain in the hip and knee, and patients may be limited in their movement, which can impair their function, especially in physically demanding activities such as walking up stairs and running.
[3] It can be conducted around the existing intramedullary fixtures, but it usually requires a subtrochanteric osteotomy, which is an invasive surgical approach where bone is cut and realigned.
[5] Correct measurement of bone malalignment with a CT scan is vital when considering an osteotomies in fixing rotational deformities, as torsional differences below 15 degrees are often easily compensated for with non surgical treatment.
Computer assisted surgery (CAS) matches a patient's anatomy with pre or intraoperatively generated fluoroscopic image data, by using camera detected infrared signals.
As a result, the surgeon can monitor in real time the position of the surgical instruments in relation to the patient's anatomy and conducts the procedure accordingly.
