MIS-TKA: Are You Still There?

Aree Tanavalee, MD
Professor and Chairman
Department of Orthopaedics
Faculty of Medicine
Chulalongkorn University
Email: areetana@hotmail.com

Abstract - Since 2002, total knee arthroplasty (TKA) using minimally invasive surgery (MIS) or MIS-TKA has been popularized worldwide. Although MIS-TKA is characterized by a 3- to 4-inch skin incision, less quadriceps injury, no patellar eversion, pain reduction, faster ambulation and shorter hospital stay, current literature has verified that the significant differences of MIS-TKA from conventional TKA are only shorter skin incision and faster early knee range of motion, especially, the first 6 to 12 weeks, postoperatively. Although infection, instability and stiffness are being concerned as the leading causes of early failure after TKA, reports of mid-term to long-term outcomes of MIS-TKA have shown similar survivorships to those of conventional TKA.Based on our 15 years of experiences, to achieve consistent satisfactory outcomes of MIS-TKA, 3 major issues must be addressed, including concepts of MIS approaches, comprehensive anesthesia & postoperative pain control, and early rehabilitation protocol.

To enhance the MIS approach in TKA, the attempt can be successfully achieved by applying 4 major principles, including mobile skin window; using a pair of retractors moving around the knee for specific surgical areas, multiple knee flexion angles; the knee being flexed at multiple angle to accommodate individual step of surgery, patellar subluxation; avoiding patellar eversion with less tension to the extensor mechanism, and facilitating instruments;

low-profile instruments to avoid skin and soft tissue damage. Evidences have verified that patients’ satisfaction on postoperative pain relates directly to the efficiency of anesthesia and postoperative pain control. Current literature demonstrated that contemporary multimodal pain control, including continuous peripheral nerve blocks and local joint infiltration in TKA provides similar effectiveness of pain control regardless of MIS or conventional surgical approach. Following the improved efficiency of postoperative pain control, contemporary postoperative rehabilitation for both approaches of TKA has moved to the so-called “enhanced recovery after surgery” (ERAS). However, one should be reminded that the aggressive rehabilitation protocol may increase knee inflammation and may develop subacute postoperative knee pain. Therefore, a well balance between rapid knee function training and control of postoperative synovial inflammation should be considered.

Keywords: minimally invasive surgery, MIS, total knee arthroplasty, TKA.