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Abstract Background Symmetry is a sign of physiological and healthy movements, as pathologies are often described by increased asymmetries. Nevertheless, based on precisely measured data, even healthy individuals will show small asymmetries in their movements. However, so far there do not exist commonly accepted methods and reference values for gait symmetry in a healthy collective. Therefore, a comparison and presentation of reference values calculated by 3 different methods of symmetry indices for lower limb joint angles during walking, ascending, and descending stairs were shown. Methods Thirty-five healthy participants were analyzed during walking, ascending, and descending stairs with the help of the inertial measurement system MyoMotion. Using the normalized symmetry index (SInorm), the symmetry index (SI) as the integral of the symmetry function, and another normalized symmetry index (NSI), the symmetry of joint angles was evaluated. For statistical evaluation of differences, repeated measurement models and Bland–Altman-Plots were used. Results Apart from a bias between the symmetry indices, they were comparable in the predefined limits of 5%. For all parameters, significantly higher asymmetry was found for ankle dorsi/-plantarflexion, compared with the hip and knee flexion. Moreover, the interaction effect of the joint and movement factors was significant, with an increased asymmetry of the hip and knee during descending stairs greater than while ascending stairs or walking, but a reduced symmetry of the ankle during walking when compared to descending. The movement only showed significant effects when analyzing the SInorm . Conclusion Even for healthy individuals, small asymmetries of movements were found and presented as reference values using 3 different symmetry indices for dynamic lower limb joint angles during 3 different movements. For the quantification of symmetrical movements differences between the joints, movements, and especially their interaction, are necessary to be taken into account. Moreover, a bias between the methods should be noted. The potential for each presented symmetry index to identify pathological movements or track a rehabilitation process was shown but has to be proven in further research. Trial registration: DRKS00025878.

Objective: To investigate the effectiveness of modified rehabilitation programmes in comparison with standard rehabilitation programmes after total knee arthroplasty through randomized controlled trials. Data sources: A search was conducted in PubMed, PubMed Central (PMC) and Cochrane Library databases in December 2020. Study selection: Randomized controlled trials were reviewed if they compared a physiotherapy exercise intervention with usual or standard physiotherapy care, or if they compared 2 types of exercise physiotherapy interventions meeting the review criteria, after total knee arthroplasty for osteoarthritis. A total of 18 randomized controlled trials were included at the end of the screening process. Data extraction: Two authors independently screened the literature, extracted data, and assessed the quality of included studies. The outcomes were knee extension, knee flexion, pain visual analogue scale, overall Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), 6-minute walking test, and Timed Up and Go test. Data synthesis: There was no clear pattern regarding which combination of starting time-point and duration of the rehabilitation programme after total knee arthroplasty significantly improves the clinical outcome when comparing modified rehabilitation programmes with standard programmes. Moreover, no particular modification to the modified programmes could be solely attributed to the improved clinical outcome in the 2 studies that showed significant improvement. Conclusion: Modified rehabilitation programmes do not result in systematic improvement in clinical outcome over one-size-fits-all-approaches after total knee arthroplasty.