Derotational femoral osteotomy yields changes in patella tilt, engagement
Click Here to Manage Email Alerts
Published results showed changes in patella tilt, patella engagement and the tibial tuberosity-trochlear groove distance after derotational femoral osteotomy.
Researchers evaluated femoral torsion, tibial torsion, knee torsion, patella tilt, axial patella engagement and tibial tuberosity-trochlear groove distance among 10 lower limbs that underwent derotational femoral osteotomy. They estimated the effect of femoral torsion on patella tilt, axial patella engagement, tibial tuberosity-trochlear groove distance and knee torsion using a linear mixed model analysis adjusted for correlation due to repeated observations.
Data showed a significant correlation between femoral torsion and axial patella engagement, patella tilt and tibial tuberosity-trochlear groove distance. Investigators found a significantly decreased axial patella engagement, an increased patella tilt and an increased tibial tuberosity-trochlear groove distance in cases of increased internal femoral torsion. However, researchers noted no correlation between change in femoral torsion and knee torsion.
“The present study can give estimations as to how much the patella tilt and engagement would be restored by derotational osteotomy before [medial patellofemoral ligament (MPFL)] reconstruction or further surgical procedures,” the researchers wrote. “This could be important because tightening of the MPFL reconstruction might differ depending on the achieved alignment. This is merely an assumption and further research is necessary.”
The researchers also noted that derotational osteotomy is not the primary treatment for patients with patella instability, who generally have multiple combined risk factors like trochlea dysplasia, patella alta, increased tibial tuberosity-trochlear groove distance or knee valgus. Before performing a derotational osteotomy, surgical treatment should primarily emphasize the correction of these risk factors that may potentially correct and alter patella tilt and engagement, according to the researchers.
“Additionally, because there is a high variance of norm values for femoral torsion and torsion itself cannot predict patella instability, a derotational osteotomy needs to be used with care,” the investigators wrote. “The benefits need to be balanced against potential complications.”
Perspective
Back to Top
John P. Fulkerson, MD
This is a well-done study in cadaver knees, and I believe the findings are accurate as well as consistent with what we would expect. Everything makes sense from a mechanical perspective. While distal external femur derotation osteotomy accomplishes a goal of improved patella engagement, tilt and tibial tuberosity-trochlear groove distance, it is a formidable procedure and, in clinical practice, tibial tubercle transfer medially or anteromedially (which provides the added benefit of tipping up the distal patella when needed) is a more benign surgical intervention for the majority of surgeons and patients. In the end, the surgeon is usually looking for improved patella engagement into the trochlea and must decide how he or she can best achieve that with least risk to the patient.
Collapse
Click Here to Manage Email Alerts