Patients with end-stage knee osteoarthritis (OA) have decreased knee-extension strength and suffer from knee pain. Strengthening of the knee-extensor muscle is a key element in conservative treatment for patients with knee OA. However, the most effective exercise dosage for knee-extension strength exercise is unknown.~In this trial the investigators investigate the efficacy of three different dosages of knee-extension strength exercise. Patients eligible for total knee replacement are offered home-based pre-operative knee-extension exercise and are randomly allocated to one of three exercise dosage groups. There is no control group. The knee-extension exercise is performed with an elastic exercise band mounted with sensor (BandCizer) which registers when the patients exercise, how much they exercise and how they exercise.~The intervention time is 12 weeks and the primary time point of interest is after exercise/just before surgery. Secondary time points of interest are shortly after surgery and three months after surgery.~The patients are given detailed exercise instruction at trial entry and hereafter they exercise unsupervised at home for 12 weeks. At week 4 and 8 they receive follow-up instruction.~Both the patients who choose not to have TKA and those who do after the exercise period will be followed with annual outcome assessments as part of a follow-up cohort.~Embedded in the trial is a qualitative study. Focus group interviews will be performed with the participating patients about their experienced enablers and barriers related to adherence to the home-based intervention, once the post-operative outcome assessment has been completed. Likewise, the orthopedic surgeons and physiotherapists allocated to the trial will undergo focus group interviews, once the trial is completed, to explore their experienced enablers and barriers related to administering the home-based intervention.~Protocol amendments 8/2-2017: Additional protocol approved by The Danish National Committee on Biomedical Research Ethics (protocol no. 55528 and 55529). Approved protocol amendments are the following inclusion and exclusion criteria: inclusion criteria age ≥45, and exclusion criteria ASA-score ≥4.~Protocol amendments 30/3-2017: Additional protocol approved by The Danish National Committee on Biomedical Research Ethics (protocol no. 57312). Approved protocol amendments are the following inclusion criteria: knee pain during the last week (NRS) ≥3, and the OKS questionnaire score has been omitted as an inclusion criteria.~Protocol amendments 6/9-2017: At the third outcome assessment (at hospital discharge, 3-8 days after surgery) only the outcomes isometric knee-extensor strength, 6MWT, SCT and current knee pain are assessed. The KOOS and OKS questionnaires as well as knee pain during the last week are omitted at this end-point as they are not validated to assess acute post-operative conditions, and use a too long recall period.
The trial investigates the efficacy of knee-extension exercise prior to total knee replacement. The participants are randomly allocated to one of three exercise dosages. There is no control group.