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Improved early outcome after TKA through an app-based active muscle training programme—a randomized-controlled trial

  • Knee
  • Published:
Knee Surgery, Sports Traumatology, Arthroscopy Aims and scope



The purpose of this prospective randomized-controlled trial (RCT) was to evaluate if an app-based feedback-controlled active muscle training programme can be used to improve the outcome in the immediate postoperative period after total knee arthroplasty (TKA).


Sixty patients, with a median age of 65.9 years (range 45–84), awaiting primary TKA were randomized into a control and training group. Both groups followed an identical postoperative protocol. In addition, the training group postoperatively performed an app-based feedback-controlled active muscle training programme multiple times daily. Outcome measures were active and passive range of motion (ROM), pain at rest and in motion, knee extension strength, the timed “Up and Go”, 10-m Walk Test, 30-s Chair Stand Test, Knee Injury and Osteoarthritis Outcome Score (KOOS), Knee Society Score (KSS), and clinical data.


The training group performed an average of 18.4 training sessions, which led to significantly higher ROM, less pain at rest and in motion, higher strength, and significantly higher functional scores. More training correlated with a better outcome.


The use of an app-based feedback-controlled active muscle training programme can improve the clinical outcome after TKA, especially ROM and reduce pain. Clinically relevant is that the training programme could be considered an alternative to continuous passive motion after total knee arthroplasty.

Level of evidence


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Body mass index


Enhanced recovery after surgery




Knee Injury and Osteoarthritis Outcome Score


Knee Society Score


Numeric rating scale


Not significant


Per protocol


Randomized-controlled trial


Range of motion


Standard deviation


Total knee arthroplasty


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Authors and Affiliations



SH and MRGS contributed equally to this study. All authors made substantial contributions. Conception and Design: SH, MRGS, TP, HH, and TSWS. Acquisition or Analysis and Interpretation of Data: SH, MRGS, GW, EL, and TSWS. Drafting or Revising the Manuscript: SH, MRGS, TP, GW, HH, EL, and TSWS. Final Approval of the Submission: SH, MRGS, TP, GW, HH, EL, and TSWS.

Corresponding author

Correspondence to Sebastian Hardt.

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Conflict of interest

Author TP has received payment by Depuy Synthes for consultancy and by Depuy Synthes and Link for development of educational presentations, but not related to this study. Author TSWS is the inventor of GenuSport and has a patent pending. The rest of the authors declare that they have no conflict of interest in relation to this manuscript.

Ethical approval

The study protocol was reviewed and approved by the institutional ethics committee (Hannover Medical School, No. 300-20016). All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.

Informed consent

Informed consent was obtained from all individual participants included in the study.

Additional information

Sebastian Hardt and Matthias R. G. Schulz shared first authorship.

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Hardt, S., Schulz, M.R.G., Pfitzner, T. et al. Improved early outcome after TKA through an app-based active muscle training programme—a randomized-controlled trial. Knee Surg Sports Traumatol Arthrosc 26, 3429–3437 (2018).

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