The Effect of Joint Line Elevation on In Vivo Knee Kinematics in Bicruciate Retaining Total Knee Arthroplasty

Prior studies have reported a negative effect on both clinical outcomes and patient-reported outcome measures (PROMS) following joint line elevation (JLE) in cruciate-retaining (CR) total knee arthroplasty (TKA) and posterior stabilized (PS) TKA designs. This experimental study was aimed to quantify the effect of JLE on in vivo knee kinematics in patients with bicruciate retaining (BCR) TKA during strenuous activities. Thirty unilateral BCR TKA patients were evaluated during single-leg deep lunge and sit-to-stand using a validated combined computer tomography and dual fluoroscopic imaging system. Correlation analysis was performed to quantify any correlations between JLE and in vivo kinematics, as well as PROMS. There was a significant negative correlation between JLE and maximum flexion angle during single-leg deep lunge (ρ = −0.34, p = 0.02), maximum varus joint angles during single-leg deep lunge (ρ = −0.37, p = 0.04), and sit-to-stand (ρ = −0.29, p = 0.05). There was a significant negative correlation between JLE and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score (ρ = −0.39, p = 0.01) and knee disability and osteoarthritis outcome score physical function (KOOS-PS; ρ = −0.33, p = 0.03). The JLE that yields a significant loss in PROMS and maximum flexion angles were 2.6 and 2.3 mm, respectively. There was a linear negative correlation of JLE with both in vivo knee kinematics and PROMS, with changes in JLE of greater than 2.6 and 2.3 mm, leading to a clinically significant loss in PROMS and maximum flexion angles, respectively, suggesting an increased need to improve surgical precision to optimize patient outcomes following BCR TKA.

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

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.

A 3D Motion Phantom for Assessing the Accuracy and Precision of Dynamic Magnetic Resonance Measurement of In Vivo Knee Kinematics

Measurement of in vivo knee kinematics can provide useful insight into disease, injury, and clinical treatment. Cartilage loading patterns are of particular interest while studying the progression of osteoarthritis [1]. However, inferring cartilage contact from skeletal kinematics requires high resolution volumetric models of cartilage surfaces and accurate skeletal positions and orientations. This is a challenging requirement at the knee, which exhibits substantial translation and non-sagittal rotation during normal activities such as gait [2]. We have recently introduced a novel 3D cine magnetic resonance (MR) imaging technique to measure in vivo tibiofemoral kinematics [3]. The purpose of this study was to develop a MR-compatible motion phantom that can generate repeatable 3D skeletal motion suitable for quantifying the accuracy and precision of kinematics derived from dynamic MRI.