Clinical outcomes in TKA are enhanced by both robotic assistance and patient specific alignment: a comparative trial in 120 patients.

INTRODUCTION: Robotically assisted surgery was introduced in total knee arthroplasty (TKA) to increase the precision of implant positioning and optimize clinical outcomes. However, the target implant position or alignment is debated. The aim of this study was twofold: to compare clinical outcomes of conventional TKA vs. robotically assisted TKA in an adjusted mechanically aligned (MA) TKA series, and to analyze the clinical effects of introducing patient-specific alignment (inverse kinematic alignment, iKA) in a robotically assisted TKA cohort. MATERIALS AND METHODS: A total of 120 patients with end stage osteoarthritis of the knee were enrolled. The first group (n = 40) received conventional adjusted MA TKA. The second group (n = 40) received robotically assisted adjusted MA TKA. The third group (n = 40) received robotically assisted iKA TKA. All patients received cruciate retaining Triathlon TKA with a uniform surgery protocol. The three groups were matched for age, sex, BMI and preoperative osteoarthritis. Preoperative and 1-year postoperative clinical outcomes were documented with the Oxford Knee Score (OKS). RESULTS: Comparison of OKS between the MA groups indicated no significant difference (p = 0.223) between the conventional TKA (group 1; 40.2 ± 5.9) and robotically assisted TKA (group 2; 42.2 ± 6.3) 1 year postoperatively. Comparison of OKS between the robotically assisted groups indicated no significant difference (p = 0.078) between the MA TKA (group 2; 42.2 ± 6.3) and iKA TKA (group 3; 44.8 ± 3.5). Comparison of conventional MA TKA (group 1; 40.3 ± 6.0) with robotically assisted iKA TKA (group 3; 44.8 ± 3.5) indicated a significant difference (p < 0.001). CONCLUSIONS: The results of this study suggest that the introduction of both patient-specific alignment and robotically assisted surgery improve clinical outcomes in TKA surgery. When access to robotic assistance is available, performing patient-specific alignment should be the objective.

Can robot-assisted total knee arthroplasty be a cost-effective procedure? A Markov decision analysis.

BACKGROUND: Total knee arthroplasty (TKA) is a frequently and increasingly performed surgery in the treatment of disabling knee osteoarthritis. The rising number of procedures and related revisions pose an increasing economic burden on health care systems. In an attempt to lower the revision rate due to component malalignment and soft tissue imbalance in TKA, robotic assistance (RA) has been introduced in the operating theatre. The primary objective of this study is to provide the results of a theoretical, preliminary cost-effectiveness analysis of RA TKA. METHODS: A Markov state-transition model was designed to model the health status of sixty-seven-year-old patients in need of TKA due to primary osteoarthritis over a twenty-year period following their knee joint replacement. Transitional probabilities and independent variables were extracted from existing literature. RESULTS: The value attributed to the utility both for primary and revision surgery has the biggest impact on the ICER, followed by the rate of successful primary surgery and the cost of RA-technology. Only 2.18% of the samples yielded from the probabilistic sensitivity analysis proved to be cost-effective (threshold set at $50000/QALY). A calculated surgical volume of at least 253 cases per robot per year is needed to prove cost-effective taking the predetermined parameter values into account. CONCLUSION: Based upon transitional probabilities and independent variables derived from existing studies, RA TKA may be cost-effective at a surgical volume of 253 cases per robot per year when compared to conventional TKA.

Knee joint laxity is restored in a bi-cruciate retaining TKA-design.

PURPOSE: The goal is to evaluate the passive stability of a bicruciate retaining, cruciate retaining and bicruciate substituting TKA design in relation to the native knee stability in terms of the laxity envelope. A bicruciate retaining knee prosthesis was hypothesized to offer a closer to normal knee stability in vitro. METHODS: Fourteen cadaveric knee specimens have been tested under passive conditions with and without external loads, involving a varus/valgus and an external/internal rotational torque, distraction/compression force and an anteroposterior shear force. Subsequently, the native knee, bicruciate retaining, cruciate retaining and finally a bicruciate substituting total knee arthroplasty were tested. RESULTS: Through the range of motion, the width of the varus/valgus and internal/external laxity envelope for the native knee and the bicruciate retaining knee were almost equivalent, whereas the cruciate retaining and the bicruciate substituting knee displayed less laxity and more joint distraction. In all prosthetic knees, an equal anteroposterior laxity was seen for the lateral and medial side whereas in the native knee, a difference in laxity was seen between the stable medial side and the more mobile lateral side. CONCLUSION: Bicruciate retaining knee prostheses can restore normal laxity and thus have the potential to offer more normal knee function. Restoration of natural peri-articular soft-tissue tension is clinically important because of its obvious effects on joint stability and range of motion. Furthermore, the results of this study could help to establish the ideal ligament tension and laxity in more conventional implants by approaching the normal values for passive knee evaluation as presented here.

Effect of three consecutive meals on the physicochemical properties of HDL and LDL in individuals with the metabolic syndrome and patients with type 2 diabetes.

BACKGROUND/OBJECTIVES: Postprandial hyperlipidemia, which is exaggerated and prolonged in insulin-resistant individuals, has been associated with cardiovascular disease. The objective of this study was to investigate whether and how the composition, size and function of high-density lipoprotein (HDL) and low-density lipoprotein (LDL) particles are affected in the postprandial state among males with the metabolic syndrome (MetS) or type 2 diabetes (T2DM), compared with controls. SUBJECTS/METHODS: A total of 14 males with T2DM, 14 with the MetS and 14 age-matched controls were given three standardized high-fat mixed meals (900 kcal; 50-g fat, 75-g carbohydrate and 35-g protein) as breakfast, lunch and dinner. Blood sampling was performed just before each meal, and 4 and 8 h after the last meal. HDL and LDL were isolated by ultracentrifugation and analyzed for their composition, particle diameter and functional properties. RESULTS: Postprandial triglycerides levels in plasma, HDL and LDL particles increased significantly in all groups (P<0.01). Compared with the control subjects, patients with T2DM had smaller LDL particles, and in agreement, a lower cholesterol-to-protein content in both fasting and postprandial samples. A prolonged increase in susceptibility of LDL to oxidation was found in all subjects, but was most evident in T2DM. The postprandial effect on LDL oxidation was associated with an increase in LDL triglyceride (r=0.29, P<0.05). In T2DM the anti-oxidative capacity of HDL trended to impairment after the third meal. CONCLUSIONS: Postprandial increases in triglycerides, especially in T2DM, are accompanied by pro-atherosclerotic functional changes in HDL and LDL particles.