JAAOS

JAAOS, Volume 25, No. KneeSupplement


How Can We Use Computational Modeling to Improve Total Knee Arthroplasty? Modeling Stability and Mobility in the Implanted Knee

Validated computational models promise a virtual platform to create optimal articular surfaces that best achieve desired implant characteristics. Today, designers can parametrically define the primary geometric features of an implant, and automatically modify design variables until stability/mobility performance objectives are best achieved. This preclinical, virtual design iteration minimizes the development cycle compared with testing physical prototypes and, by evaluating a broader scope of design concepts, likely improves the clinical performance of the final product. However, the scenario described is not without shortcomings and requires thorough understanding of the capabilities and the limitations of the models used. Although models typically represent the articular interface well, the interaction with the patient and the surgical process includes significant variability and increase in complexity. We present current modeling capabilities for the estimation of implant stability/mobility, with further suggestions for answering the difficult question of how an implant might perform throughout the population.

      • Subspecialty:
      • Knee

    Implementation of Patient-reported Outcome Measures in Total Knee Arthroplasty

    Patient-reported outcome measures (PROMs) has emerged as a strategy to improve the outcome of total knee arthroplasty. The use of PROMs in routine clinical practice has accelerated because health care in the United States is shifting from a volume-based to a value-based reimbursement system in which quality is increasingly being measured using PROMs. Electronic, internet-based platforms, such as Functional and Outcomes Research for Comparative Effectiveness in Total Joint Replacement, currently exist which offer turn-key solutions for PROM collection, trending, analysis, and benchmarking for busy clinicians. Successful systems provide real-time trended PROM scores that inform shared decision making, optimize patient care, and enable comparisons among practices.

        • Subspecialty:
        • Knee

      Intraoperative Measurements and Tools to Assess Stability

      Knee stability is the ability for the joint to maintain an appropriate functional position throughout its range of motion. Knee instability can be defined as excessive laxity during activities of daily living. Intraoperative knee laxity can be affected by implant design, alignment of components, and soft-tissue balancing. Soft-tissue balance is a major contributor to knee instability. Mechanical balancing instruments can be classified as spacer blocks or joint-distraction devices. Conventional wisdom favors rectangular and equal flexion–extension gaps. However, knee balance is elusive even with mechanical balancing instruments. First-generation electronic balancing devices are equivalent in concept to spacer blocks instrumented with force sensors. Second-generation electronic balancing devices are equivalent in concept to mechanical distraction devices instrumented with pressure and displacement sensors. Electronic ligament balancers can be useful in documenting intraoperative knee laxity for quantifiable correlation with postoperative outcomes, thus directly relating postoperative stability to surgical balance, and may predict outcomes and knee stability.

          • Subspecialty:
          • Knee

        Joint Stability in Total Knee Arthroplasty: What Is the Target for a Stable Knee?

        Instability remains a common cause of failure in total knee arthroplasty. Although approaches for surgical treatment of instability exist, the target for initial stability remains elusive, increasing the likelihood that failures will persist because adequate stability is not restored when performing the primary arthroplasty. Although the mechanisms that stabilize the knee joint—contact between the articular surfaces, ligamentous constraints, and muscle forces—are well-defined, their relative importance and the interplay among them throughout functions of daily living are poorly understood. The problem is exacerbated by the complex multiplanar motions that occur across the joint and the large variations in these motions across the population, suggesting that stability targets may need to be patient-specific.

            • Subspecialty:
            • Knee

          Microbiology and Antimicrobial Challenges of Prosthetic Joint Infection

          Research that leads to better strategies to diagnose and treat prosthetic joint infection (PJI) is critical because PJI is a devastating complication of total knee arthroplasty. A key to the diagnosis and management of PJI is defining the microbiology of PJI and improving the medical management of PJI utilizing both systemic and local antimicrobial therapy. In this review, the author will present his opinions on future research needs as they relate to the microbiology of PJI, including antimicrobial resistance and the antimicrobial treatment of PJI. This paper summarizes a presentation given at a recent multidisciplinary research conference entitled “Strategies to improve total knee arthroplasty” sponsored by the Knee Society. It was a part of a session entitled “Periprosthetic Joint Infection.”

              • Subspecialty:
              • Knee

            Orthopaedic Infection: Prevention and Diagnosis

            Host optimization, reduction of bacteria, and establishing proper wound environment in the preoperative, intraoperative, and postoperative periods are the traditional cornerstones of infection prevention. Most institutions have standardized a systems approach to reduce the incidence of surgical site infections. Typically, these systems-based approaches promote protocols for hand and environmental hygiene, patients risk assessment and screening, surgical delays for identifiable and modifiable risk factors, infection surveillance, antibiotic stewardship programs, communication/coordination of care, physician 360° reporting, and unit-based safety programs. Despite the institution of these prevention efforts, there remains controversy about the efficacy and cost-effectiveness of a number of these approaches.

                • Subspecialty:
                • Knee

              Patient-reported Outcome Measurement for Patients With Total Knee Arthroplasty

              Total knee arthroplasty is a large contributor to Medicare costs. In an effort to lower costs and improve outcomes, the Centers for Medicaid and Medicare Services has implemented the Comprehensive Care for Joint Replacement model, which incentivizes surgeons to submit both general health and joint-specific patient-reported outcome measures (PROMs). However, in addition to using PROMs for reporting purposes, surgeons should also consider incorporating PROMs into clinical practice. Currently, PROMs are not widely implemented in the clinical setting despite their value in measuring factors such as patients' expectations and mental state, which impact outcomes. Furthermore, as technology improves, PROM collection will become faster and more efficient. The information collected by PROMs can inform treatment decisions and facilitate communication between the surgeon and the patient.

                  • Subspecialty:
                  • Knee

                Preclinical Evaluation of Photoacoustic Imaging as a Novel Noninvasive Approach to Detect an Orthopaedic Implant Infection

                Introduction: Diagnosing prosthetic joint infection (PJI) poses significant challenges, and current modalities are fraught with low sensitivity and/or potential morbidity. Photoacoustic imaging (PAI) is a novel ultrasound-based modality with potential for diagnosing PJI safely and noninvasively.

                Materials: In an established preclinical mouse model of bioluminescent Staphylococcus aureus PJI, fluorescent indocyanine green (ICG) was conjugated to β-cyclodextrin (CDX-ICG) or teicoplanin (Teic-ICG) and injected intravenously for 1 week postoperatively. Daily fluorescent imaging and PAI were used to localize and quantify tracer signals. Results were analyzed using 2-way analysis of variance.

                Results: Fluorescence clearly localized to the site of infection and was significantly higher with Teic-ICG compared with CDX-ICG (P = 0.046) and ICG alone (P = 0.0087). With PAI, the photoacoustic signal per volumetric analysis was substantially higher and better visualized with Teic-ICG compared with CDX-ICG and ICG alone, and colocalized well with bioluminescence and fluorescence imaging.

                Conclusion: Photoacoustic imaging successfully localized PJI in this proof-of-concept study and demonstrates potential for clinical translation in orthopaedics.

                    • Subspecialty:
                    • Knee

                  Research Priorities for Optimal Use of Patient-reported Outcomes in Quality and Outcome Improvement for Total Knee Arthroplasty

                  The national Functional and Outcomes Research for Comparative Effectiveness in Total Joint Replacement program routinely collects pre- and postoperative patient-reported outcomes for clinicians to use when making individual patient treatment decisions and monitoring aggregate quality of care and outcomes. When the pre–post gains in pain or function at one site vary from the national norms, the next question is, “how do we improve?” This paper will use the traditional quality management's framework of inputs (patients), processes (clinical care), and outcomes to outline priority research questions to learn how clinicians, hospital managers, and patients can interpret patient-reported outcomes to improve total knee arthroplasty care and outcomes. In summary, research should identify best practices to minimize variation in a patient's health status before surgery, tailor peri–total knee arthroplasty care pathways to match individual patient risks to optimize safe care, and implement patient-reported measures to document optimal outcomes.

                      • Subspecialty:
                      • Knee

                    Staphylococcal Biofilms and Immune Polarization During Prosthetic Joint Infection

                    Staphylococcal species are a leading cause of community- and nosocomial-acquired infections, where the placement of foreign materials increases infection risk. Indwelling medical devices and prosthetic implants are targets for staphylococcal cell adherence and biofilm formation. Biofilm products actively suppress proinflammatory microbicidal responses, as evident by macrophage polarization toward an anti-inflammatory phenotype and the recruitment of myeloid-derived suppressor cells. With the rise in prosthetic hip and knee arthroplasty procedures, together with the recalcitrance of biofilm infections to antibiotic therapy, it is imperative to better understand the mechanism of crosstalk between biofilm-associated bacteria and host immune cells. This review describes the current understanding of how staphylococcal biofilms evade immune-mediated clearance to establish persistent infections. The findings described herein may facilitate the identification of novel treatments for these devastating biofilm-mediated infections.

                        Strategies to Prevent Periprosthetic Joint Infection After Total Knee Arthroplasty and Lessen the Risk of Readmission for the Patient

                        There is yet to be a standardized total knee arthroplasty (TKA) surgical protocol that has been studied to a sufficient degree to offer evidence-based practices regarding infection and readmission prevention. Although high-level evidence is often sought to provide guidance concerning protocol- and process-level decisions, the literature is often confusing and nondefinitive in its conclusions and recommendations regarding periprosthetic joint infection and readmission prevention. Areas of study that require further investigation include the following: the role of patient optimization and preoperative mitigation of risk; perioperative antibiotics; operating room environment; blood management; operative techniques, implants, and infection prevention measures; wound care management; and post acute care. Patient-associated modifiable risk must be optimized to decrease poly joint infection rates after TKA. Protocol measures for TKA need to be standardized, and evidence-based practice measures need to be validated.

                            • Subspecialty:
                            • Knee

                          Value-based Purchasing for Osteoarthritis and Total Knee Arthroplasty: What Role for Patient-reported Outcomes?

                          Prompted by the aims to improve the patient experience of care (including quality and satisfaction), improve the health of populations, and reduce the per capita cost of health care, the US healthcare system is embarking upon a new era in care delivery that seeks to optimize healthcare value. Value, the consideration of quality relative to cost, can be increased by improving quality, reducing cost, or doing both. Given that patient-reported outcomes related to pain, function, and quality of life underlay both the reason patients seek care for and the benchmarks by which treatment success is measured for osteoarthritis, measures of these patient-reported outcomes figure prominently in understanding the quality and hence value. Directed attention to patient-reported outcomes has the potential to drive quality and efficiency improvements, but only if the quality measures that are developed from them are clinically important, scientifically acceptable, usable, and feasible.

                              • Subspecialty:
                              • Knee

                            What Postoperative Outcome Measures Link Joint Stability to Patient Satisfaction?

                            Total knee arthroplasty is a common, effective treatment for disabling arthritis of the knee. However, not all patients receiving total knee arthroplasty achieve what is considered an optimal outcome, and not all patients report high satisfaction with their results. Because the focus of attention increasingly turns to optimizing outcomes and utilization of healthcare resources, it is worthwhile to review the array of available tools and techniques for quantifying postoperative outcomes after knee arthroplasty and identify how these might be used to guide refinement of the treatment to achieve even better and more predictable outcomes. This review summarizes current methods for assessing postoperative outcomes on a biomechanical basis, organizes them into three complementary domains, and suggests how these domains must be linked to address the titular question.

                                • Subspecialty:
                                • Knee

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