We sought to evaluate the early post-operative active range-of-motion (AROM) between robotic-assisted total knee arthroplasty (raTKA) and conventional TKA (cTKA). A secondary data analysis on a global prospective cohort study was performed. A propensity score method was used to select a matched control of cTKA from the same database using 1:1 ratio, based on age, sex, BMI, and comorbidity index. This resulted in 216 raTKA and cTKA matched cases. Multivariable longitudinal regression was used to evaluate difference in ROM over time and values are reported as least squares means (95% confidence interval). The longitudinal model tested the treatment effect (raTKA vs cTKA), time effect, and their interaction with control on covariance of patients ‘s age, sex, BMI, comorbidity and pre-operative flexion. Logistic regression was used to analyze the active flexion level at one month (cut by 90°) and three months (cut by 110°). At one-month postoperative the raTKA cases had more AROM for flexion by an average of 5.54 degrees (p<0.001). There was no difference at three months (p=0.228). The raTKA group had a greater improvement from pre-operative values at both one-month, with an average 7.07° (3.6°, 10.5°, p<0.001) more improvement, and at three-months with an average improvement of 4° more (1.61°, 7.24°, p=0.0115). AROM for extension was lower overall in the raTKA group by an average of 0.44° (p=0.029). The raTKA patients had higher odds of achieving ≥90° of flexion at one-month (OR 2.15, 95% CI 1.16, 3.99). raTKA resulted in greater AROM flexion gains in the early postoperative period than cTKA. Additional research is needed to understand if these earlier gains in AROM are associated with improved patient satisfaction and continued improvements with time

Introduction. Many groups consider passive flexion to be a good indicator of postoperative success, to the point where this outcome directly influences certain outcome scores such as Knee Society Scores (KSS). However, it is alternatively believed that normal-like kinematics result in better TKA outcomes, and previous fluoroscopy studies have demonstrated that there are many parameters that affect weight-bearing range-of-motion. The objective of this study to investigate the correlations between patient-reported outcomes, passive flexion, and weight-bearing knee kinematics. Methods. The femorotibial kinematics, passive and weight-bearing range-of-motion, and KOOS and KSS for 291 TKA subjects were collected in a retrospective study. The average age, BMI, and post-op time was 69.2±7.2 years, 29.3±4.6, and 22.4±16.3 months, respectively. Pearson correlation analysis was used to find the statistical correlations between the various parameters, and two-tailed t-tests were carried out to find statistical differences. Results. Superior weight-bearing flexion was statistically correlated with both higher KOOS (r=0.2122, p=0.0094) and KSS (r=0.2986, p<.0001), shown in Table 1. Interestingly, there was no correlation with respect to passive flexion and KOOS (r=0.1363, p=0.0975). Correlations between KSS and passive flexion were not analyzed due to the inherent covariance between these parameters. Furthermore, subjects with paradoxical anterior sliding of either condyle had significantly lower KSS scores than those without anterior sliding (81.1±11.9 versus 84.4±12.4 for lateral, p=0.03, and 82.2±12.1 versus 85.1±12.5 for medial, p=0.02). Conclusion. The results of this study revealed that weight-bearing flexion and not passive flexion is a better predictor of TKA outcomes. Subjects having greater weight-bearing flexion demonstrated higher KOOS and KSS scores. Also, subjects that experienced a paradoxical anterior slide had a statistically lower KSS than those subjects that experienced posterior femoral rollback. Therefore, it may be more important to evaluate weight-bearing flexion during clinical exams. For any figures or tables, please contact the authors directly

Introduction. Wearable sensors are promising tools for fast clinical gait evaluations in individuals with osteoarthritis (OA) of the knee and hip. However, gait assessments with wearable sensor are often limited to relatively simple straight-ahead walking paradigms. Parameters reflecting more complex and relevant aspects of gait, including dual-tasking, turning, and compensatory upper body motion are often overlooked in literature. The aim of this study was to investigate turning, dual-task performance, and upper body motion in individuals with knee or hip OA in addition to spatiotemporal gait parameters, taking shared covariance between gait parameters into account. Methods. Gait was compared between individuals with unilateral knee (n=25) or hip (n=26) OA scheduled for joint replacement, and healthy controls (n=27). For 2 minutes, subjects walked back-and-forth a 6 meter trajectory making 180 degree turns, with and without a secondary cognitive task. Gait parameters were collected using four inertial measurement units on feet, waist, and trunk. To test if turning, dual-tasking, and upper body motion had added value above common spatiotemporal parameters, a factor analysis was conducted. Standardized mean differences were computed for the comparison between knee or hip OA and healthy controls. One gait parameter was selected per gait domain based on factor loading and effect size for the comparison between OA groups and healthy controls. Results. Four independent domains of gait were obtained: speed-spatial, speed-temporal, dual task cost, and upper body motion. Turning parameters were part of the speed-temporal domain. From the gait domains that were obtained, stride length (speed-spatial) and cadence (speed-temporal) had the strongest factor loadings and effect sizes for both knee and hip OA, and lumbar sagittal range of motion (upper body motion) for hip OA only. Although dual-task cost was an independent domain, it was not sensitive to knee or hip OA. Conclusions. Stride length, cadence, and lumbar sagittal range of motion were non-redundant and sensitive gait parameters, representing (compensatory) gait adaptations in individuals with knee or hip OA. Turning or dual-task parameters had limited additional value for evaluating gait in knee and hip OA, although dual-task cost constituted a separate gait domain. These findings hold promise for objective gait assessments in the clinic using wearable sensors. Future steps should include testing responsiveness of these gait domains to interventions aiming to improve mobility, including knee and hip arthroplasty

Aims

It is well described that patients with bone and joint infections (BJIs) commonly experience significant functional impairment and disability. Published literature is lacking on the impact of BJIs on mental health. Therefore, the aim of this study was to assess health-related quality of life (HRQoL) and the impact on mental health in patients with BJIs.

In general TKA can be divided into two distinct groups: cruciate retaining and cruciate substituting. The cam and post of the latter system is in fact a mechanical substitution of the intricate posterior cruciate ligament. In our previous work we and many other investigators have focused on the movement of the femoral component relative to the tibial tray. Little information is available about the relative movement between the cam part of the femoral component and the post of the tibial insert. In this study we determine the distance and the changes in distance between the cam of the femoral component and the tibial post during extension, flexion at 90° and full flexion. The secondary purpose is to analyse possible differences between FBPS and MBPS TKA. Methods. 12 subjects' knees were imaged using fluoroscopy from extension over 90° to maximum kneeling flexion. The images were digitized. The 3-dimensional (3D) position and orientation of the implant components were determined using model-based shape-matching techniques, manual matching, and image-space optimization routines. The implant surface model was projected onto the geometry-corrected image, and its 3D pose was iteratively adjusted to match its silhouette with the silhouette of the subject's TKA components. The results of this shapematching process have standard errors of approximately 0.5° to 1.0° for rotations and 0.5 mm to 1.0 mm for translations in the sagittal plane. Joint kinematics were determined from the 3D pose of each TKA component using the 3-1-2 Cardan angle convention. This process resulted in a distance map of the femoral and tibial surfaces, from which the minimum separations were determined for the purpose of this study between cam and post (fig1.). Separation distances between the tibial polyethylene (PE) insert's post and the femoral prosthesis component have been calculated in three steps. First, the surface models of all three components as well as their position and orientation were extracted from the data files produced by the fluoroscopic kinematic analysis. Next, a set of 12 points were located on the post of each tibial insert (fig2.). Finally, for each point, the distance to the femoral component was quantified. For each step in this process, custom MATLAB. (r). (The MathWorks(tm) Inc., Natick, MA, USA) programs were used. For each of the 12 points on the post, a line was constructed through the point and parallel to the outward-facing local surface normal of the post. The resulting set of lines was then intersected with the femoral component model. Intersection points where lines ran “out of” the femoral component, detected by a positive dot product of the femoral component surface normal with the post surface normal (used to define the line), were discarded. Finally, the distances between the 12 points on the post and the intersection points on each line were calculated. For each line, the smallest distance was retained as a measure of the separation between insert and femoral component. Where a line did not intersect the femoral component, the corresponding separation distance was set to infinity. In each position, distances are measured at 6 pairs of points. Two indices of asymmetry are analysed: . The absolute difference between both measurements within a pair. Perfect symmetry is present when this absolute difference equals zero. The proportion of pairs where one of both measurements equals infinity. Indeed, this situation refers to the presence of ‘extreme’ asymmetry. A linear model for repeated measures is used to analyse the absolute differences as a function of the between-subjects factor condition (mobile bearing or fixed bearing) and the within-subject factors position (4 levels) and pair (6 levels). More specifically, a direct likelihood approach is adopted using a compound symmetric covariance matrix. Results. There is a significant difference in absolute difference between the fixed and mobile bearing condition (p=0.046). On average, the absolute difference is higher in the fixed bearing condition, 1.75 (95%CI: 1.39;2.11) vs 1.20 (95%CI:0.78;1.62). (fig2.). Conclusion. The separation distances between post and cam show less asymmetry in the Rotating platform TKA, meaning less or no contact between the post and cam surfaces which are possible sources of wear