Higher Axial Tibiofemoral Rotation and Functional Outcomes with Mobile-Bearing Compared with Fixed-Bearing Total Knee Arthroplasty at 1- but Not at 2-Year Follow-Up—A Randomized Clinical Trial

Abstract

The objective of this study was to determine in vivo knee kinematics and clinical outcomes of patients who underwent fixed- and mobile-bearing total knee arthroplasty (TKA) at 1- and 2-year follow-up. This prospective double-blinded randomized controlled trial was performed from November 2011 to December 2012. A total of 64 patients were randomized to fixed- and mobile-bearing TKA groups (32 patients in each group). All patients were evaluated with the following: three-dimensional in vivo knee kinematics analysis during gait, stepping up and stepping down stair steps, and getting up from and sitting on a chair; and knee range of motion and patient-reported outcome measures (Knee Outcome Survey Activities of Daily Living Scale [KOS-ADLS] and pain visual analog scale [VAS]) at 1- and 2-year follow-up. Descriptive statistics (means, standard deviations, and percentages) were calculated for all variables. The Kolmogorov–Smirnov test was used to test if variables were normally distributed. A Student's t-test was used to compare continuous variables between patients in the two groups. The chi-square test was used to compare the groups with respect to categorical variables. The α level for statistical significance was set at p < 0.05. The mean axial tibiofemoral rotation in patients who underwent mobile-bearing TKA was significantly higher during gait (13.3 vs. 10.7), stepping up (12.8 vs. 10) stair steps, and getting up (16.1 vs. 12.1) from a chair compared with fixed-bearing TKA patients at 1-year follow-up (p < 0.05). KOS-ADLS function score was significantly higher in the mobile-bearing compared with the fixed-bearing TKA group (32 vs. 27.7) at 1-year follow-up (p < 0.05). No significant difference in kinematics and clinical outcomes between fixed- and mobile-bearing TKA groups was observed at 2-year follow-up (p > 0.05). Based on the results of this study, mobile-bearing TKA allowed a higher degree of rotation when walking, stepping up stair steps, and standing up from a chair, and had higher functional outcomes compared with fixed-bearing TKA at 1-year follow-up. However, no difference in in vivo kinematics or in clinical outcomes was observed between fixed- and mobile-bearing prostheses at 2-year follow-up.

Does mobile-bearing have better flexion and axial rotation than fixed-bearing in total knee arthroplasty? A randomised controlled study based on gait

“…'s study concluded that MB TKA allowed a higher degree of axial tibiofemoral rotation when walking, stepping up stair steps, and standing up from a chair and had higher functional outcomes compared with FB TKA at 1-year follow-up by knee kinematics analysis. But, they did not compare with the healthy group [34]. Zürcher et al.…”

No difference between mobile and fixed bearing in primary total knee arthroplasty: a meta-analysis

“…The minimal functional improvement may be explained by greater axial rotation promoted by the MB implants [ 29 , 53 , 99 ]. Amaro et al [ 8 ] evaluating kinematic differences in 64 patients, found that axial rotation was higher in the MB group after 1 year, but disappeared at 2-year follow-up. A histological study showed the development of fibrotic tissue in the synovial membrane and infrapatellar fat pad after a TKA [ 3 ].…”

“…A histological study showed the development of fibrotic tissue in the synovial membrane and infrapatellar fat pad after a TKA [3]. This produces a hardening effect that may minimize the kinematic differences between the MB and FB groups [8] The rate of deep infection was strongly influenced by the study by Breeman et al [17], which weighted 17.6% on the final effect. Indeed, when conducting the analyses without those data [17], the rate of deep infection is similar between the two groups.…”

“…However, the difference was minimal, and whether mobile bearing provide better outcomes remains controversial [ 5 , 16 , 38 , 46 , 63 , 82 , 96 , 100 , 103 , 111 ]. Several randomized clinical trials (RCTs), which have not been yet considered in any previous meta-analyses, have recently been recently published [ 8 , 24 , 28 , 59 , 93 , 105 , 107 , 123 ]. An update of current evidence could clarify whether MB implants promote greater outcomes to FB in TKA in terms of outcome and complication rate.…”

Mobile Bearing versus Fixed Bearing for Total Knee Arthroplasty: Meta-analysis of Randomized Controlled Trials at Minimum 10-Year Follow-up

“…of motion (ROM) of the knee joint, 10 and provide better functional outcomes. 11 Meanwhile, several disadvantages of MB-TKA were described, such as dislocation of the insert, an increased risk of soft tissue impingement, and a prolonged learning curve. 12,13 Although MB-TKA has some theoretical advantages compared with FB-TKA, controversy still remains which type of prosthesis provides better clinical and radiographic outcomes in long-term follow-up.…”