[Future implications of navigation in total knee arthroplasty]. / Gibt es noch Gründe für die Navigation in der Knieendoprothetik?

BACKGROUND: After more than two decades of experience with computer-assisted knee arthroplasty, extensive experience and study data are available, allowing a profound evaluation. Undoubtedly, computer-assisted knee arthroplasty has been proven to achieve excellent results for implant positioning and long-leg axis reconstruction. Thus, computer-assisted knee arthroplasty represents the current gold standard to avoid unintended malpositioning of total knee components for neutrally aligned implants and individualized implant alignment (kinematic alignment, adjusted mechanical alignment, and others). Previous studies could not show significant differences in functional outcomes and patient satisfaction. However, recent meta-analyses showed relevant advantages of computer-assisted knee arthroplasty. These results could be based on further developments in software-assisted soft tissue balancing and more sensitive evaluation methods of follow-up examinations. LONG-TERM OUTCOME: Further, international registries show advantages of computer-assisted knee arthroplasty regarding long-term outcomes. In particular, the Australian arthroplasty registry describes a significantly lower revision rate due to aseptic loosening/osteolysis in the computer-assisted knee arthroplasty group, analyzing a period of up to 17 years. These positive effects can already be proven six months following surgery. FUTURE PROSPECTS: However, despite demonstrated benefits, computer-assisted knee arthroplasty has not yet become established in daily routine, and wide regional variations in its use are observed. Newer developments such as robotic-assisted knee arthroplasty, primarily based on navigation techniques, are currently being heavily promoted. However, this new technology must justify its enormous additional costs and prove its advantages compared to computer-assisted knee arthroplasty. In the backdrop of the development of computer-assisted knee arthroplasty, this might be a difficult task.

Development, piloting, and evaluation of an evidence-based informed consent form for total knee arthroplasty (EvAb-Pilot): a protocol for a mixed methods study.

BACKGROUND: Practitioners frequently use informed consent forms to support the physician-patient communication and the informed consent process. Informed consent for surgery often focuses on risk centered information due to high liability risks for treatment errors. This may affect patients' anxiety of adverse events and the nocebo effect. This study focuses on the optimization of pre-surgical information on risks and complications, and at the same time reconciles these information with legal requirements. METHODS: The development, piloting, and evaluation of evidence-based informed consent forms for total knee arthroplasty (TKA) and related anesthesia procedures will follow the UK MRC Framework for developing and evaluating complex interventions. Conducting different sub-studies, we will (I) qualitatively explore the information acquisition and decision-making processes, (II) develop and pilot test evidence-based informed consent forms on the example of TKA and related anesthesia procedures, (III) conduct a monocentric interrupted time series (ITS) pilot study to evaluate the effects of evidence-based informed consent forms in comparison with standard consent forms, and (IV) perform a process evaluation to identify barriers and facilitators to the implementation of the intervention and to analyze mechanisms of impact. DISCUSSION: The evidence-based and understandable presentation of risks in informed consent forms aims at avoiding distorted risk depiction and strengthening the patients' competencies to correctly assess the risks of undergoing surgery. This might reduce negative expectations and anxiety of adverse events, which in turn might reduce the nocebo effect. At the same time, the practitioners' acceptance of evidence-based informed consent forms meeting legal requirements could be increased. TRIAL REGISTRATION: ClinicalTrials.gov, NCT04669483 . Registered 15 December 2020. German Clinical Trials Registry, DRKS00022571 . Registered 15 December 2020.

Femoral flexion position is a highly variable factor in total knee arthroplasty: an analysis of 593 conventionally aligned total knee replacements.

PURPOSE: In contrast to coronal alignment, only few is known about sagittal alignment in total knee arthroplasty (TKA). The aim of this study was to identify the flexion position of the femoral component in a routine surgical setting of conventional TKA and to evaluate potential predictors for the degree of femoral flexion. METHODS: A retrospective study was performed on 593 primary TKA using the conventional intramedullary alignment technique for distal femur. Femoral flexion was measured by the verification mode of a pinless navigation system. Correlations between femoral flexion and patient-specific data, surgery-related factors and measurements of a preoperative anterior-posterior long-leg X-ray were analysed. RESULTS: The distal femoral resection showed a mean flexion of 5.5° ± 2.5° to the mechanical axis with high variation between 2.5° extension and 14° flexion. In a multivariate regression model, body height (p = 0.023), body weight (p = 0.046) and body mass index (p = 0.026) showed significant positive correlation to femoral flexion. There was no correlation to any preoperative alignment data from the anterior-posterior long-leg film. The sagittal position was also independent from surgery-related factors such as different knee systems or surgeons. CONCLUSIONS: Femoral flexion is a highly variable characteristic in conventionally aligned TKA. Increasing body height, body weight and body mass index were identified as predictors for a high degree of femoral flexion. LEVEL OF EVIDENCE: III.