Kinematic or Mechanical Alignment? Award Winning Study Says “No Difference”

Question: Which is better for total knee arthroplasty (TKA) patients—kinematic alignment or mechanical alignment techniques?

According to Casey Tingle, writing for Helio Orthopaedcs Today, researchers found that there was no difference when they looked at 2-year functional outcomes of either kinematic alignment or mechanical alignment techniques during implantation.

Simon W. Young, M.D., FRACS of the University of Auckland in New Zealand, told Orthopedics Today Europe, “We found no difference in 2-year patient-reported outcome scores in TKAs implanted using the kinematically aligned vs. mechanically aligned technique. We did not find evidence for the theoretical advantages of improved pain and function that form the basis of the design rationale for kinematic alignment.”

For the study researchers randomly assigned 99 patients undergoing primary TKA with the Triathlon prosthesis (Stryker) to either a mechanical alignment or kinematic alignment group. They assessed all patients’ preoperative alignment with full-length MRIs and their postoperative alignment with CT scans. The team also assessed the functional scores for these patients preoperatively and at 6-weeks, 6-months, 1-year and 2-years postoperatively.

To ensure mechanical alignment accuracy, researchers used computer navigation in the mechanical alignment group and in the kinematic alignment group. They also manufactured patient-specific cutting blocks based on patients’ individual preoperative MRI data.

Young presented the study results to the Knee Society Specialty Day Meeting, in Orlando, Florida, where he received the Chitranjan S. Ranawat, M.D., Award for this research. “For Oxford Knee Score, which was our main outcome, we saw no difference in the clinical outcome score at 2 years between the kinematic and mechanically aligned groups, ” Young said. Both study groups had similar complication rates.