Component position and overall limb alignment following total knee arthroplasty (TKA) have been shown to influence prosthetic survivorship and clinical outcomes. Robotic-assisted (RA) total knee arthroplasty has demonstrated improved accuracy to plan in cadaver studies compared to conventionally instrumented (manual) TKA, but less clinical evidence has been reported. The objective of this study was to compare the three-dimensional accuracy to plan of RATKA with manual TKA for overall limb alignment and component position. A non-randomized, prospective multi-center clinical study was conducted to compare RATKA and manual TKA at 4 U.S. centers between July 2016 and August 2018. Computed tomography (CT) scans obtained approximately 6 weeks post-operatively were analyzed using anatomical landmarks. Absolute deviation from surgical plans were defined as the absolute value of the difference between the CT measurements and surgeons’ operative plan for overall limb, femoral and tibial component mechanical varus/valgus alignment, tibial component posterior slope, and femoral component internal/external rotation. We tested the differences of absolute deviation from plan between manual and RATKA groups using stratified Wilcoxon tests, which controlled for study center and accounted for skewed distributions of the absolute values. Alpha was 0.05 two-sided. At the time of this abstract, data collections were completed for two centers (52 manual and 58 RATKA).Introduction
Methods
Component position and overall limb alignment following total knee arthroplasty (TKA) have been shown to influence prosthetic survivorship and clinical outcomes1. The objective of this study was to compare the accuracy to plan of three-dimensional modeled (3D) TKA with manual TKA for component alignment and position. An open-label prospective clinical study was conducted to compare 3D modeling with manual TKA (non-randomized) at 4 U.S. centers between July 2016 and August 2018. Men and women aged > 18 with body mass index < 40kg/m2 scheduled for unilateral primary TKA were recruited for the study. 144 3DTKA and 86 manual TKA (230 patients) were included in the analysis of accuracy outcomes. Seven high-volume, arthroplasty fellowship-trained surgeons performed the surgeries. The surgeon targeted a neutral (0°) mechanical axis for all except 9 patients (4%) for whom the target was within 0°±3°. Computed tomography (CT) scans obtained approximately 6 weeks post-operatively were analyzed using anatomical landmarks to determine femoral and tibial component varus/valgus position, femoral component internal/external rotation, and tibial component posterior slope. Absolute deviation from surgical plan was defined as the absolute value of the difference between the CT measurement and the surgeon's operative plan. Smaller absolute deviation from plan indicated greater accuracy. Mean component positions for manual and 3DTKA groups were compared using two-sample t tests for unequal variances. Differences of absolute deviations from plan were compared using stratified Wilcoxon tests, which controlled for study center and accounted for skewed distributions of the absolute values. Alpha was 0.05 two-sided. At the time of this report, CT measurements of femoral component rotation position referenced from the posterior condylar axis were not yet completed; therefore, the current analysis of femoral component rotation accuracy to plan reflects one center that exclusively used manual instruments referencing the transepicondylar axis (TEA).Introduction
Methods
The aim of this study was to evaluate near-infrared spectroscopy
(NIRS) as a continuous, non-invasive monitor for acute compartment
syndrome (ACS). NIRS sensors were placed on 86 patients with, and 23 without
(controls), severe leg injury. NIRS values were recorded for up
to 48 hours. Longitudinal data were analyzed using summary and graphical
methods, bivariate comparisons, and multivariable multilevel modelling.Aims
Patients and Methods
To determine the effect of altering tibial slope on the two-year range of motion (ROM) of patients undergoing condylar total knee replacements (TKR). A single surgeon performed 74 primary cemented posterior stabilised tri-compartmental TKR’s on 56 patients (19 male, 37 female) with mean age of 67.1 years, height 66.7in., weight 187.4 lb, and BMI 29.58 kg/m2. 51 had osteoarthritis, and five had rheumatoid arthritis. A standard surgical technique was employed utilising flexion axis localisation to position the femoral components. Patients were followed for two years minimum using outcome measures and x-rays. Knees where tibial slope was restored to a degree angle equal to, or slightly greater than, their pre-op slope (group 1) were compared to knees where tibial slope was decreased (group 2). The average 2 year post-op ROM in Group 1 was significantly greater than that of Group 2 (129.3 degrees vs. 120.5 degrees, p=.001). The average pre-op to post-op increase in ROM in Group 1 was significantly greater than Group 2 (38.1 degrees vs.27.7 degrees, p=.003). Correlational analysis revealed that restoration of pre-op tibial slope was the primary determinant of post-op ROM, followed by pre-op ROM, then weight and BMI (each to significance of p<
0.05). Restoration of tibial slope clearly produced increased ROM in this study. Using one standard slope cut for every tibia may prevent many patients from achieving their maximum potential ROM.
