Is minimally invasive surgery in total knee arthroplasty really minimally invasive surgery?

Minimization of soft-tissue damage is one of the primary purposes behind the application of minimally invasive surgery (MIS) in total knee arthroplasty (TKA). A consecutive series of 147 TKAs were enrolled in the present study, with 96 MIS-TKAs using 11 quadriceps-sparing, 46 subvastus, 32 midvastus, and 7 parapatellar approaches and 51 conventional TKAs using 22 subvastus, 9 midvastus, and 20 parapatellar approaches. Serum levels of creatinine phosphokinase, myoglobin, aldolase, lactate dehydrogenase, glutamic oxaloacetic transaminase, and creatinine were measured on postoperative days 0, 1, 2, 4, 7, and 14. Postoperative rising index (RI) was expressed as a proportion of the preoperative value. When RIs were compared between MIS-TKA and conventional TKA, no significant differences were found for any enzymes. Interestingly, the midvastus approach displayed the highest RIs for creatinine phosphokinase and myoglobin between the 4 vastus-splitting approaches. Consequently, degree of muscle damage was equivalent between MIS-TKA and conventional TKA, whereas types of vastus-splitting approach appeared closely related to muscle damage.