Issue: July 2012
July 03, 2012
2 min read

Award-winning study: MIS approach no better than standard technique for TKA

Issue: July 2012
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In a level 1 study, researchers from the Mayo Clinic found no significant differences in objective and subjective function at 2-months follow-up between minimally invasive subvastus and conventional medial parapatellar approaches for total knee arthroplasty.

“When done with advanced pain management and rapid rehabilitation protocols, the minimally invasive approach was not better than the standard approach,” Mark W. Pagnano, MD, said during his presentation of the John Insall Award-winning study at the 2012 Specialty Day Meeting of the Knee Society. “Total knee replacement results in dramatic improvement in perceived outcome for the patient, quadriceps strength [and] gait analysis — that is not dependent on the surgical approach.”

Pagnano said the trial was conducted with the knowledge that previous studies lacked functional outcome data to determine whether minimally invasive surgical (MIS) TKA produces better results than conventional TKA.

“Some of the limitations in the prior literature also include the fact that over the last decade, we have made substantial gains in pain management, the introduction of rapid rehabilitation protocols and early dismissal protocols,” Pagnano said.

Mark W. Pagnano 

Mark W. Pagnano

To explore whether MIS TKA provides a measurable benefit in today’s hospital setting, Pagnano and colleagues conducted a randomized double-blinded, single-surgeon study of 40 patients who underwent total knee arthroplasty performed with either a MIS subvastus approach that took care to not evert the patella or a traditional medial parapatellar approach. The groups were similar regarding age, gender and body mass index. Two patients in each group dropped out of the study.

The groups completed preoperative and 2-months postoperative evaluations using the SF-12, Knee Society score, Knee Injury and Osteoarthritis Outcome Score and the University of California Los Angeles activity score. Patient-reported outcomes were also recorded with a milestone diary. The investigators also recorded patients’ isometric quadriceps strength preoperatively and at 2-months follow-up. In addition, they performed a 3-D gait analysis at both time points and at 2-year follow-up.

Both groups showed marked improvements in function, quality of life, quadriceps strength and pain reduction preoperatively to 2-month follow-up, and there were no significant differences between the groups for these measures. Gait analysis also revealed similar improvements between the groups for single limb support time, walking cadence and speed, gait kinematics and kinetics, knee flexion/extension and knee power generation/absorption.

“Overall, we can say there was a substantial improvement in clinical scores, quadriceps strength, return to activities of daily living and improvements in all of the gait parameters on level walking and stair climbing,” Pagnano said. “We could not detect a difference between the MIS and conventional approach to total knee arthroplasty.”– by Jeff Craven

  • Wegrzyn J, Parratte S, Coleman-Wood K, et al. A randomized controlled trial of minimally invasive TKR: Comprehensive gait and strength testing outcomes. Presented at the 2012 Specialty Day Meeting of The Knee Society. February 11. San Francisco.
For more information:
  • Mark W. Pagnano, MD, can be reached at Department of Orthopedic Surgery, Mayo Clinic, 200 First St. SW, Rochester, MN 55944; email:
  • Pagnano receives royalties from DePuy and MAKO Surgical Group and is a consultant to Stryker Orthopaedics.