Increasing Trunk Mass Evokes Lower Extremity Biomechanical Plasticity during Stair Descent

International Journal of Exercise Science 16(1): 942-953, 2023. The purpose of this study was to investigate the influence of simulated changes in body mass on lower extremity joint work and relative joint contributions during stair descent. Ten healthy recreationally active college-age participants performed five stair descent trials in each of five loading conditions: no added load and with an additional 5%, 10%, 15% and 20% of their body weight. Three-dimensional ankle, knee and hip joint powers were calculated using a six degree-of-freedom model in Visual3D (C-Motion Inc., Germantown, MD, USA). Sagittal plane joint work was calculated as the joint power curve integrated with respect to time during the period between initial contact and toe off. Prism 9.0 (GraphPad Inc., San Diego, CA) was used to perform univariate 1 x 5 repeated measures analyses of variance to determine the effect of added mass on absolute and relative joint work values for total and for each lower extremity joint independently. Increasing added mass was associated with greater total lower extremity negative work during the stair descent task (p \u3c 0.001). At the ankle, increasing added mass was associated with increasing magnitudes of negative joint work. Increasing added mass was associated with greater relative contributions of the ankle and reduced knee contributions to total negative lower extremity joint work (p = 0.014 and p = 0.006). The current findings demonstrated increases in ankle joint contributions to total lower extremity work while knee joint contributions to total lower extremity work were reduced in response to increasing added mass

Biomaterial Hypersensitivity: Is It Real? Supportive Evidence and Approach Considerations for Metal Allergic Patients following Total Knee Arthroplasty

The prospect of biomaterial hypersensitivity developing in response to joint implant materials was first presented more than 30 years ago. Many studies have established probable causation between first-generation metal-on-metal hip implants and hypersensitivity reactions. In a limited patient population, implant failure may ultimately be related to metal hypersensitivity. The examination of hypersensitivity reactions in current-generation metal-on-metal knee implants is comparatively limited. The purpose of this study is to summarize all available literature regarding biomaterial hypersensitivity after total knee arthroplasty, elucidate overall trends about this topic in the current literature, and provide a foundation for clinical approach considerations when biomaterial hypersensitivity is suspected

Biomaterial Hypersensitivity: Is It Real? Supportive Evidence and Approach Considerations for Metal Allergic Patients following Total Knee Arthroplasty

The prospect of biomaterial hypersensitivity developing in response to joint implant materials was first presented more than 30 years ago. Many studies have established probable causation between first-generation metal-on-metal hip implants and hypersensitivity reactions. In a limited patient population, implant failure may ultimately be related to metal hypersensitivity. The examination of hypersensitivity reactions in current-generation metal-on-metal knee implants is comparatively limited. The purpose of this study is to summarize all available literature regarding biomaterial hypersensitivity after total knee arthroplasty, elucidate overall trends about this topic in the current literature, and provide a foundation for clinical approach considerations when biomaterial hypersensitivity is suspected

Association of Accelerometry-Measured Physical Activity and Cardiovascular Events in Mobility-Limited Older Adults: The LIFE (Lifestyle Interventions and Independence for Elders) Study.

BACKGROUND:Data are sparse regarding the value of physical activity (PA) surveillance among older adults-particularly among those with mobility limitations. The objective of this study was to examine longitudinal associations between objectively measured daily PA and the incidence of cardiovascular events among older adults in the LIFE (Lifestyle Interventions and Independence for Elders) study. METHODS AND RESULTS:Cardiovascular events were adjudicated based on medical records review, and cardiovascular risk factors were controlled for in the analysis. Home-based activity data were collected by hip-worn accelerometers at baseline and at 6, 12, and 24 months postrandomization to either a physical activity or health education intervention. LIFE study participants (n=1590; age 78.9±5.2 [SD] years; 67.2% women) at baseline had an 11% lower incidence of experiencing a subsequent cardiovascular event per 500 steps taken per day based on activity data (hazard ratio, 0.89; 95% confidence interval, 0.84-0.96; P=0.001). At baseline, every 30 minutes spent performing activities ≥500 counts per minute (hazard ratio, 0.75; confidence interval, 0.65-0.89 [P=0.001]) were also associated with a lower incidence of cardiovascular events. Throughout follow-up (6, 12, and 24 months), both the number of steps per day (per 500 steps; hazard ratio, 0.90, confidence interval, 0.85-0.96 [P=0.001]) and duration of activity ≥500 counts per minute (per 30 minutes; hazard ratio, 0.76; confidence interval, 0.63-0.90 [P=0.002]) were significantly associated with lower cardiovascular event rates. CONCLUSIONS:Objective measurements of physical activity via accelerometry were associated with cardiovascular events among older adults with limited mobility (summary score >10 on the Short Physical Performance Battery) both using baseline and longitudinal data. CLINICAL TRIAL REGISTRATION:URL: http://www.clinicaltrials.gov. Unique identifier: NCT01072500

Total knee arthroplasty kinematics may be assessed using computer modeling: a feasibility study.

The next generational leap in computer navigation will hopefully aid surgeons in personalizing surgical techniques to patients\u27 individual anatomical variables to optimize outcomes. To effectively use the information obtained in the operating room, a multitude of kinematic variables must be conveyed to the orthopedic surgeon in a usable and coherent manner. This study used an intraoperative navigation system to record passive knee kinematics after a total knee arthroplastyperformed. The clinical measures were taken via research software with the ability to record kinematic data in 10-second intervals. The data from 10 consecutive clinical cases were averaged, and the translation (anterior/posterior) and rotation (internal/external) were recorded and compared from 0° to 100° of flexion to allow for comparison with the previously recorded computer model. Model and clinical curves compared favorably, with less than 1° rotational and 1.5-mm differences, on average. The comparison of information and analyses were reviewed to indicate how they might be interpreted in the operating room for future use during surgery to allow a more personalized approach to improving functional outcomes after total knee arthroplasty. Copyright 2012, SLACK Incorporated

Computer modeling to predict effects of implant malpositioning during TKA.

Computer-assisted surgery has focused on alignment of implants and soft tissue balancing but the end results during surgery as they pertain to long-term function of the implants are not yet realized. One parameter that continues to be variable despite the use of computer navigation is the placement of the implants in the transverse plane. The objective of this study was to determine whether implant and anatomic registrations could be used in a computer model (LifeMOD/KneeSIM, LifeModeler, Inc., San Clemente, California) to show differences in the resulting contact patterns of the medial and lateral condyles of the polyethylene insert. The simulations included tibiofemoral and patellofemoral contact, passive soft tissue (medial and lateral collateral, and posterior cruciate ligaments, as well as the capsular tissues), and active muscle elements (quadriceps and hamstrings). Components of a fixed-bearing cruciate-retaining total knee (Columbus knee system; B. Braun Aesculap, Tuttlingen, Germany) were imported into the model. The systems were subjected to one 60-second cycle of a lunge. Both the femoral and the tibial components were positioned in 5° of internal or external rotation in varying combinations and the resulting kinematics analyzed. The resulting kinematics showed variations in anteroposterior translation of the lateral and medial femoral condyles that resembled several of those reported in the literature for individual patients with a cruciate-retaining knee implant system. Copyright 2010, SLACK Incorporated