Does Minimally Invasive Total Knee Arthroplasty Improve Isokinetic Torque?

Abstract

Background Less invasive dissection of the extensor apparatus, one of the aspects of minimally invasive surgical (MIS) TKA, might result in less reduction of postoperative quadriceps strength. However, it is unclear whether MIS is associated with less strength reduction. Questions/purposes We asked whether knee strength (extensor or flexor torque) would be greater in patients having a MIS TKA compared with patients having a standard TKA and whether knee scores, alignment, ROM, tourniquet and operating times, and hospital length of stay were improved. Methods We prospectively recruited 52 patients awaiting MIS or standard TKA, matched for age, weight, height, BMI, sex, and surgically treated side, but not randomized. Isokinetic tests were performed preoperatively and postoperatively to obtain peak values of extensor and flexor torque. Postoperative-to-preoperative ratios and the extensor-flexor torque ratio also were calculated. Results Mean baseline extensor torques were 57 Nm and 53 Nm for MIS and standard TKAs, respectively. At 8 weeks postoperatively, absolute values of the mean postoperative knee extensor torque also were similar: 47 and 45 Nm for patients with MIS and standard TKAs, respectively. The postoperative-to-preoperative ratios were 0.8 for extensor and flexor torque in both groups. The extensor-flexor torque ratios were similar between groups. Conclusions Our data suggest a less invasive dissection of the extensor apparatus involved in MIS TKA does not enhance postoperative quadriceps strength. Level of Evidence Level III, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

Knee Extensor Strength and Gait Characteristics After Minimally Invasive Unicondylar Knee Arthroplasty vs Minimally Invasive Total Knee Arthroplasty: A Nonrandomized Controlled Trial

“…Others reported that the extent of quadriceps injury inflicted while performing knee arthroplasty correlates with postoperative knee extensor strength in the early postoperative course after knee arthoplasty [31][32][33]. Therefore, an MIS may be advantageous although no benefit for longer term recovery has been seen [34,35].…”

Isokinetic Extension Strength Is Associated With Single-Leg Vertical Jump Height

“…Before testing, patients completed a 10-minute warm-up on a stationary bicycle, and if needed, they were allowed to perform individual dynamic stretching and jumping. The isokinetic testing protocol was based on the protocol described by Liebensteiner et al 23 All tests were administered by the same researcher, who followed a standardized method for measuring peak extension and flexion torque using an isokinetic dynamometer (Con-Trex MJ; CMV AG). The testing protocol consisted of concentric quadriceps and hamstring contractions.…”

“…The testing protocol consisted of concentric quadriceps and hamstring contractions. 23 The patients started with the noninjured leg and performed 4 repetitions at an angular velocity of 60 deg/s. Angular velocity was automatically prescribed and controlled by the Con-Trex testing device software.…”

Mini-midvastus total knee arthroplasty does not result in superior gait pattern

“…Recently, the results of our MIS versus standard TKA population were published in terms of other outcome parameters: WOMAC scores, knee extensor/flexor torque, radiographic outcome and tourniquet/operating time [ 12 ]. We found WOMAC score, knee extensor and flexor strength to have equal results, and leg axis, component positioning and tourniquet/operating time in MIS patients to even be slightly inferior.…”

“…Those findings of static alignment are in good agreement with the valgus kinematics during gait (dynamic alignment) observed in the current study. The slightly inferior component positioning and whole leg alignment in MIS TKA were attributed to the limited surgical access [ 12 ].…”