Is Minimally Invasive Surgery Better than Conventional Total Knee Arthroplasty?

    Over the past decade, orthopaedic surgeons have been interested in using a minimally invasive surgery (MIS) technique for total knee arthroplasty (TKA). They point to studies suggesting that a minimally invasive approach has a positive impact on early outcomes after TKA, making it a better option than the conventional approach to TKA.

    A limitation of these reports, however, is that they are primarily retrospective studies or case series that lack objective functional outcomes data, such as gait analysis and thigh musculature strength.

    Mark W. Pagnano, MD, and his colleagues at Mayo Clinic, Rochester, Minnesota, sought to answer the question of whether MIS is better than conventional TKA, and at the recent ICJR West meeting, Dr. Pagnano presented the results of their study.

    Study Objective

    • Determine if TKA performed through a mini-subvastus approach improves subjective and objective functional outcomes compared with a standard medial parapatellar approach

    Materials and Methods

    • Randomized controlled trial; single surgeon (Dr. Pagnano) performed all procedures
    • Patients stratified into two groups: mini-subvastus approach (least amount of muscle invasion) or standard medial parapatellar approach
    • Dynamic balancing of groups based on age, gender, and body mass index
    • Assessments preoperatively and at 2 months and 2 years postoperatively
    • Comprehensive gait analysis, including level walking and stair ascent and descent
    • Isometric quadriceps strength testing
    • Typical questionnaires: SF-12, Knee Society Score (KSS), Knee Injury and Osteoarthritis Outcome Score (KOOS), UCLA activity scale


    • No substantial differences between groups in patients’ perceived outcome and quality of life (pain scores, function and activity level) at 2 months posteroperatively
    • No substantial differences between groups in quadriceps strength
    • No substantial differences between groups in gait parameters (spatiotemporal parameters, kinematics/kinetics, stair ascent/descent)

    Dr. Pagnano stated that he and his colleagues saw a dramatic improvement in both groups, with no differences between MIS and a conventional approach to TKA when considering clinical scores, quadriceps strength, milestone ADLs, or gait parameters.

    He and his colleague believe that previous studies reporting improved outcomes with MIS were probably flawed, and that the observed improvements in those studies were more likely attributable to multimodal pain regimens and rapid rehabilitation protocols than to the MIS approach.

    Click the button below to watch Dr. Pagnano’s presentation.