BackgroundPatients undergoing total knee arthroplasty (TKA) often experience strength deficits both pre- and post-operatively. As these deficits may have a direct impact on functional recovery, strength assessment should be performed in this patient population. For these assessments, reliable measurements should be used. This study aimed to determine the inter- and intrarater reliability of hand-held dynamometry (HHD) in measuring isometric knee strength in patients awaiting TKA.MethodsTo determine interrater reliability, 32 patients (81.3% female) were assessed by two examiners. Patients were assessed consecutively by both examiners on the same individual test dates. To determine intrarater reliability, a subgroup (n = 13) was again assessed by the examiners within four weeks of the initial testing procedure. Maximal isometric knee flexor and extensor strength were tested using a modified Citec hand-held dynamometer. Both the affected and unaffected knee were tested. Reliability was assessed using the Intraclass Correlation Coefficient (ICC). In addition, the Standard Error of Measurement (SEM) and the Smallest Detectable Difference (SDD) were used to determine reliability.ResultsIn both the affected and unaffected knee, the inter- and intrarater reliability were good for knee flexors (ICC range 0.76-0.94) and excellent for knee extensors (ICC range 0.92-0.97). However, measurement error was high, displaying SDD ranges between 21.7% and 36.2% for interrater reliability and between 19.0% and 57.5% for intrarater reliability. Overall, measurement error was higher for the knee flexors than for the knee extensors.ConclusionsModified HHD appears to be a reliable strength measure, producing good to excellent ICC values for both inter- and intrarater reliability in a group of TKA patients. High SEM and SDD values, however, indicate high measurement error for individual measures. This study demonstrates that a modified HHD is appropriate to evaluate knee strength changes in TKA patient groups. However, it also demonstrates that modified HHD is not suitable to measure individual strength changes. The use of modified HHD is, therefore, not advised for use in a clinical setting.
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Background The gait modification strategies Trunk Lean and Medial Thrust have been shown to reduce the external knee adduction moment (EKAM) in patients with knee osteoarthritis which could contribute to reduced progression of the disease. Which strategy is most optimal differs between individuals, but the underlying mechanism that causes this remains unknown. Research question Which gait parameters determine the optimal gait modification strategy for individual patients with knee osteoarthritis? Methods Forty-seven participants with symptomatic medial knee osteoarthritis underwent 3-dimensional motion analysis during comfortable gait and with two gait modification strategies: Medial Thrust and Trunk Lean. Kinematic and kinetic variables were calculated. Participants were then categorized into one of the two subgroups, based on the modification strategy that reduced the EKAM the most for them. Multiple logistic regression analysis with backward elimination was used to investigate the predictive nature of dynamic parameters obtained during comfortable walking on the optimal modification gait strategy. Results For 68.1 % of the participants, Trunk Lean was the optimal strategy in reducing the EKAM. Baseline characteristics, kinematics and kinetics did not differ significantly between subgroups during comfortable walking. Changes to frontal trunk and tibia angles correlated significantly with EKAM reduction during the Trunk Lean and Medial Thrust strategies, respectively. Regression analysis showed that MT is likely optimal when the frontal tibia angle range of motion and peak knee flexion angle in early stance during comfortable walking are high (R2Nagelkerke = 0.12). Significance Our regression model based solely on kinematic parameters from comfortable walking contained characteristics of the frontal tibia angle and knee flexion angle. As the model explains only 12.3 % of variance, clinical application does not seem feasible. Direct assessment of kinetics seems to be the most optimal strategy for selecting the most optimal gait modification strategy for individual patients with knee osteoarthritis.
MULTIFILE
: Knee injuries commonly occur in later stages of competition indicating that fatigue may influence dynamic knee stability. Force sense (FS) is a submodality of proprioception influenced by muscle mechanoreceptors, and, if negatively affected by fatigue, may results in less effective neuromuscular control. OBJECTIVES: To determine the effects of peripheral fatigue on FS of the quadriceps and hamstrings. DESIGN: Quasi-experimental study design. PARTICIPANTS: Twenty healthy and physically active females and males (age: 23.4±2.7 years, mass: 69.5±10.9kg, height: 169.7±9.4cm) participated. INTERVENTIONS: Fatigue was induced during a protocol with two sets of 40 repetitions, and the last set truncated at 90 repetitions or stopped if torque production dropped below 25% of peak torque. MAIN OUTCOME MEASURES: FS of the hamstrings and quadriceps was tested on separate days before and after three sets of isokinetic knee flexion and extension to fatigue by examining the ability to produce a target isometric torque (15% MVIC) with and without visual feedback (FS Error). Electromyographic data of the tested musculature were collected in order to calculate and determine median frequency shift. T-tests and Wilcoxon Signed Rank tests were conducted to examine pre-fatigue and post-fatigue FS Error for flexion and extension. RESULTS: Despite verification of fatigue via torque production decrement and shift in median frequency, no significant differences were observed in FS Error for either knee flexion (pre=0.54±2.28 N·m; post=0.47±1.62 N·m) or extension (pre=-0.28±2.69 N·m; post=-0.21±1.78 N·m) pre-fatigue compared to the post-fatigue condition. CONCLUSIONS: Although previous research has demonstrated that peripheral fatigue negatively affects TTDPM, it did not affect FS as measured in this study. The peripheral fatigue protocol may have a greater effect on the mechanoreceptors responsible for TTDPM than those responsible for FS. Further investigation into the effects of fatigue across various modes of proprioception is warranted.
