Patella Eversion Reduces Early Knee Range of Motion and Muscle Torque Recovery after Total Knee Arthroplasty: Comparison between Minimally Invasive Total Knee Arthroplasty and Conventional Total Knee Arthroplasty

Abstract

We hypothesized that patella eversion during total knee arthroplasty (TKA) reduces early return of active knee extension and flexion, quadriceps muscle strength, and postoperative pain. In 100 conventional TKA knees and 100 minimally invasive TKA (MIS TKA) knees, we compared knee range of motion (ROM), postoperative pain, and quadriceps muscle strength at 1 day, 4 days, 1 week, 2 weeks, 3 weeks, 4 weeks, 12 weeks, 1 year, and 5 years after surgery. The differences of surgical approach between MIS TKA and conventional TKA of this study are length of skin incision with subcutaneal flap and patella eversion. In MIS TKA, skin incision is shorter than conventional TKA. Furthermore, patella is not everted in MIS TKA procedure. There were no significant differences in preoperative factors. Postoperative improvement of ROM, postoperative muscle strength recovery, and postoperative improvement of visual analog scale were faster in patients with MIS TKA when compared to that in patients with conventional TKA. On the other hand, no significant difference was observed in complication, 5-year clinical results of subjective knee function score, and the postoperative component angle and lower leg alignment. These results indicate that patella eversion may affect muscle strength recovery and postoperative pain.

Does Minimally Invasive Total Knee Arthroplasty Improve Isokinetic Torque?

“…Many authors assessed quadriceps function in terms of rehabilitation milestones (eg, straight leg raise) after MIS and standard TKAs [8,16,20,25,33]. The findings in those studies are consistent, in that quadriceps function was superior with a MIS TKA during the first postoperative week [8,16,33].…”

“…Many authors assessed quadriceps function in terms of rehabilitation milestones (eg, straight leg raise) after MIS and standard TKAs [8,16,20,25,33]. The findings in those studies are consistent, in that quadriceps function was superior with a MIS TKA during the first postoperative week [8,16,33]. Only a few studies reported on quadriceps function in terms of rehabilitation milestones beyond the first postoperative week; Kolisek et al [25] reported no strength differences 12 weeks after surgery, and the strength findings observed by Karpman and Smith [20] 2 weeks postoperative were dependent on the type of MIS approach (quadriceps-sparing superior, but mini-midvastus not superior as compared with medial parapatellar).…”

“…Quadriceps outcome in terms of rehabilitation milestones might be dependent on the subjective interpretation of the observer. Other authors investigated knee extensor (and partly flexor) torque as an objective parameter of quadriceps function after MIS and standard TKAs [5,23,33,37,44]. The findings from those studies are inconsistent.…”

“…The findings from those studies are inconsistent. Some reported better extensor torque during the first 4 weeks postoperative in patients who had MIS, which no longer was present in the following months [33,37,44]. Others found equal extensor torque during the first postoperative measurements among patients who had MIS and standard TKAs, but better torque after 1 year in patients who had MIS [23].…”

“…Others reported better results for 3 and 12 months postoperative among patients who had MIS [5]. In addition to the incongruent findings, most of the mentioned studies did not assess the torque ratio between knee extension and flexion [5,33,37,44], although it was reported as a parameter indicating quadriceps-hamstrings imbalance [21,26,35,36].…”