TKA: Standing Alignment Doesn’t Predict Dynamic Alignment

Do you really need to aim for a straight limb when doing a total knee arthroplasty (TKA)?

The jury is out, but researchers from the UK and France have new evidence that says “no.”

Their work, “Does standing limb alignment after total knee arthroplasty predict dynamic alignment and knee loading during gait?” was published online March 24, 2017 in The Knee.

Charles Rivière, M.D., Ph.D. a consulting orthopedic surgeon at the MSK Lab, Imperial College London told OTW, “Postoperative standing frontal limb alignment has recently been shown to have little effect on clinical outcomes of mechanically aligned (MA) TKA. We thought the reason was maybe the poor relationship between standing (static) and dynamic (gait) frontal limb alignment.”

“We designed a prospective study to assess this question. The study included 35 patients operated with a MA posterior stabilized TKA who had a postoperative assessment of their standing (full leg X-ray) and dynamic (gait analysis for level walking) alignments plus their dynamic adduction moment.”

“The standing alignment was found to be of poor value to predict the dynamic alignment and adduction moment during level walking activity. We’ve all been taught during our training period that creating a straight limb when performing a TKA would be biomechanically sensible and reduce constraints apply on the prosthetic knee, therefore reducing risks of accelerated polyethylene wear and implant loosening. I’m not saying this statement is wrong, however modern tools enabling dynamic assessment show a reality which is much more complex.”

“The standing limb alignment is only one of the many parameters which influence the dynamic limb alignment. Residual laxity after TKA, prosthetic knee kinematics, gait pattern, femoral bone torsion etc. are probably other relevant influential parameters needing investigation.”