No difference in early functional outcomes for mini-midvastus and limited medial parapatellar approaches in navigation-assisted total knee arthroplasty: a prospective randomized clinical trial

Patients desire less pain and faster recovery of range of knee motion after total knee arthroplasty (TKA). While minimal invasive surgery (MIS) TKA appears to meet these needs, concerns exist regarding component malpositioning. Navigation systems can reduce the incidence of component misalignment. The present prospective randomized study compared limited medial parapatellar (LMPP) and mini-midvastus (MMV) approaches in 30 patients who had bilateral simultaneous primary TKAs. Each patient underwent LMPP on one knee and MMV on the other. Both approaches were navigation-assisted. We primarily analyzed postoperative pain (using visual analog scores), range of knee motion, and hospital for special surgery (HSS) scores in the first 6 postoperative months (i.e., the early postoperative period), and secondarily analyzed perioperative parameters and radiographic outcomes. The LMPP and MMV approaches were found to be similar in terms of pain measured at postoperative 3 days, 1, 2 weeks, 1, 3, and 6 months (P = NS). Similarly, the 2 approaches were found to be similar in terms of range of motion measured at 1, 2 weeks, 1, 3, and 6 months (P = NS), and in terms of HSS scores measured at 1, 3, and 6 months (P = NS). There were also no differences between groups in terms of total blood loss, approach preferred by patients, and radiographic component positioning. The present study found that navigation-assisted MMV and navigation-assisted LMPP resulted in similar outcomes in terms of pain, ROM, HSS score, and radiologic outcomes over the first six postoperative months. We recommend the LMPP approach over the MMV approach in navigation-assisted MIS TKA because it is more familiar to surgeons and is easier to convert to the conventional approach where necessary.