Influence of advanced prosthetic knee joints on perceived performance and everyday life activity level of low-functional persons with a transfemoral amputation or knee disarticulation

Contains fulltext : 108351.pdf (publisher's version ) (Open Access)OBJECTIVE: To assess the effects of two types of microprocessor-controlled prosthetic knee joints (MPKs) on perceived performance and everyday life activity level. DESIGN: Randomized cross-over trial. SUBJECTS: Thirty persons with a unilateral above-knee amputation or knee disarticulation classified as Medicare Functional Classification Level-2. METHODS: Participants were measured in 3 conditions, i.e. using a mechanically controlled prosthesis, an MPK featuring a microprocessor-controlled stance and swing phase (MPKA), and an MPK featuring a microprocessor-controlled stance phase (MPKB). Subjects' perceived performance regarding prosthesis use was measured with the Prosthesis Evaluation Questionnaire. Subjects' activity level was quantified using accelerometry. As high within-group variability regarding subjects' functional performance was expected to impede detection of possible effects of an MPK, data were analysed for the total group and for 3 subgroups of participants. RESULTS: Participants' perception regarding ambulation, residual limb health, utility, and satisfaction with walking were significantly higher in the MPKA condition compared with the mechanical knee joint condition. Participants' activity level was similar in all knee joint conditions. CONCLUSION: Although Medicare Functional Classification Level-2 amputees report benefitting in terms of their performance from using an MPK, this is not reflected in their actual daily activity level after one week of using an MPK

Correlation between localized strain and damage in shear-loaded Pb-free solders

A digital image correlation (DIC) algorithm was employed to measure microscopic strain-field evolution in shear-loaded model solder interconnections made out of a number of Sn-based alloys. Four different solder alloys studied were Sn–36Pb–2Ag, Sn–3.8Ag–0.7Cu (SAC), Sn–3.3Ag–3.82Bi, and Sn–8Zn–3Bi. The measured strain fields were correlated with damage observed at the scale of the sample, and at microscopic length scales.Local strain differs significantly from applied global strain and has been shown to depend on the geometry of the samples as well as the microstructure (on a grain level) of the solder.Strain fields in all solder interconnections were found to localize near but not at the solder–substrate interface and along grain boundaries in the solders. The eventual failure path as observed on the scale of the sample (parallel to the two solder–substrate interfaces with a cross-over from one interface to the other somewhere in the connection) showed a good correlation with measured strain fields in all interconnections.In contrast to the similarity on a macroscopic scale, on a microscopic scale the failure mechanisms were observed to be material specific

Lateral trunk lean and medializing the knee as gait strategies for knee osteoarthritis

To determine (1) if Medial Thrust or Trunk Lean reduces the knee adduction moment (EKAM) the most during gait in patients with medial knee osteoarthritis, (2) if the best overall strategy is the most effective for each patient and (3) if these strategies affect ankle and hip kinetics.publisher: Elsevier articletitle: Lateral trunk lean and medializing the knee as gait strategies for knee osteoarthritis journaltitle: Gait & Posture articlelink: http://dx.doi.org/10.1016/j.gaitpost.2016.11.014 content_type: article copyright: © 2016 Elsevier B.V. All rights reserved.status: publishe

Lateral trunk lean and medializing the knee as gait strategies for knee osteoarthritis

Objective: To determine (1) if Medial Thrust or Trunk Lean reduces the knee adduction moment (EKAM) the most during gait in patients with medial knee osteoarthritis, (2) if the best overall strategy is the most effective for each patient and (3) if these strategies affect ankle and hip kinetics. Design: Thirty patients with symptomatic medial knee osteoarthritis underwent 3-dimensional gait analysis. Participants received verbal instructions on two gait strategies (Trunk Lean and Medial Thrust) in randomized order after comfortable walking was recorded. The peaks and impulse of the EKAM and strategy-specific kinematic and kinetic variables were calculated for all conditions. Results: Early stance EKAM peak was significantly reduced during Medial Thrust (29%). During Trunk Lean, early and late stance EKAM peak and EKAM impulse reduced significantly (38%, 21% and 25%, respectively). In 79% of the subjects, the Trunk Lean condition was significantly more effective in reducing EKAM peak than Medial Thrust. Peak ankle dorsi and plantar flexion, knee flexion and hip extension and adduction moments were not significantly increased. Conclusions: Medial Thrust and Trunk Lean reduced the EKAM during gait in patients with knee osteoarthritis. Individual selection of the most effective gait modification strategy seems vital to optimally reduce dynamic knee loading during gait. No detrimental effects on external ankle and hip moments or knee flexion moments were found for these conditions

FEASIBILITY OF A NEW CONCEPT FOR MEASURING ACTUAL FUNCTIONAL PERFORMANCE IN DAILY LIFE OF TRANSFEMORAL AMPUTEES

Objective: Determining the feasibility of implementing a new concept to objectively evaluate actual functional abilities of transfemoral amputees into a new measuring tool called "Assessment of Daily Activity Performance in Transfemoral amputees" (ADAPT). Design: Study 1: cross-sectional design. Study 2: repeated measures design. Subjects: Study 1 comprised two groups of 10 participants, age range 19-72 years. One group used microprocessor-controlled knee joints and the other group used mechanically controlled knee joints. Study 2 comprised 20 participants, age range 31-68 years. Methods: Two versions of ADAPT were assessed in the separate studies. In study 1 performance times on version 1 of ADAPT were compared between groups. In study 2 participants completed version 2 of ADAPT twice with a 1 h rest between trials. The Locomotor Capabilities Index was administered. Reliability was determined by calculating correlation coefficients and by Bland-Altman analyses. Results: In study 1, ADAPT version 1 proved to be sensitive in detecting differences in performance between groups. In study 2, 75% of all correlation coefficients exceeded 0.90 in version 2 of ADAPT. Bland-Altman analyses showed high test-retest agreement. Conclusion: It is feasible to reliably assess actual functional abilities of transfemoral amputees using standardized simulations of daily activities. This ADAPT concept is able to differentiate between different functional performance levels

Lateral trunk lean and medializing the knee as gait strategies for knee osteoarthritis

Objective To determine (1) if Medial Thrust or Trunk Lean reduces the knee adduction moment (EKAM) the most during gait in patients with medial knee osteoarthritis, (2) if the best overall strategy is the most effective for each patient and (3) if these strategies affect ankle and hip kinetics. Design Thirty patients with symptomatic medial knee osteoarthritis underwent 3-dimensional gait analysis. Participants received verbal instructions on two gait strategies (Trunk Lean and Medial Thrust) in randomized order after comfortable walking was recorded. The peaks and impulse of the EKAM and strategy-specific kinematic and kinetic variables were calculated for all conditions. Results Early stance EKAM peak was significantly reduced during Medial Thrust (−29%). During Trunk Lean, early and late stance EKAM peak and EKAM impulse reduced significantly (38%, 21% and −25%, respectively). In 79% of the subjects, the Trunk Lean condition was significantly more effective in reducing EKAM peak than Medial Thrust. Peak ankle dorsi and plantar flexion, knee flexion and hip extension and adduction moments were not significantly increased. Conclusions Medial Thrust and Trunk Lean reduced the EKAM during gait in patients with knee osteoarthritis. Individual selection of the most effective gait modification strategy seems vital to optimally reduce dynamic knee loading during gait. No detrimental effects on external ankle and hip moments or knee flexion moments were found for these conditions

Lateral trunk lean and medializing the knee as gait strategies for knee osteoarthritis

Objective To determine (1) if Medial Thrust or Trunk Lean reduces the knee adduction moment (EKAM) the most during gait in patients with medial knee osteoarthritis, (2) if the best overall strategy is the most effective for each patient and (3) if these strategies affect ankle and hip kinetics. Design Thirty patients with symptomatic medial knee osteoarthritis underwent 3-dimensional gait analysis. Participants received verbal instructions on two gait strategies (Trunk Lean and Medial Thrust) in randomized order after comfortable walking was recorded. The peaks and impulse of the EKAM and strategy-specific kinematic and kinetic variables were calculated for all conditions. Results Early stance EKAM peak was significantly reduced during Medial Thrust (−29%). During Trunk Lean, early and late stance EKAM peak and EKAM impulse reduced significantly (38%, 21% and −25%, respectively). In 79% of the subjects, the Trunk Lean condition was significantly more effective in reducing EKAM peak than Medial Thrust. Peak ankle dorsi and plantar flexion, knee flexion and hip extension and adduction moments were not significantly increased. Conclusions Medial Thrust and Trunk Lean reduced the EKAM during gait in patients with knee osteoarthritis. Individual selection of the most effective gait modification strategy seems vital to optimally reduce dynamic knee loading during gait. No detrimental effects on external ankle and hip moments or knee flexion moments were found for these conditions