Patients allocated to the no intervention group will receive encouragement to stay active and be encouraged to gradually return to activities of daily living. This will be the only exercise-encouragement given to the no-intervention group.

The unsupervised rehabilitation group will receive a written exercise program in order to perform daily exercises at home. The exercise program will be made using Exorlive (for more information about Exorlive please visit https://www.exorlive.com). In addition to the written program, patients will able to use a link provided to see small video-instructions on the internet of each exercise on the program. No feedback or supplementary instructions will be given after the initial face-to-face appointment.

This subscale consists of 17 questions related to the patient's function in activities of daily living such as "descending stairs", "standing" and "getting in/out of car". The subscale is scored by the degree of difficulty the patient experiences in the last week on a 5-point Likert scale (none, mild, moderate, severe, and extreme), and calculated to a score ranging from 0 (worst/extreme difficulties) to 100 (best/ no problems). The total questionnaire takes about 10 minutes to complete. At least 50% of the questionnaire items are required to be answered to permit calculation of a mean score.

These subscales are scored by the degree of difficulty the patient has experienced in the last week on a 5-point Likert scale. Each subscale provides a score, which can be calculated to a total score ranging from 0 (worst/extreme difficulties) to 100 (best/ no problems). At least 50% of the questionnaire items in each subscale are required to be answered to permit calculation of a mean score.

These subscales are scored by the degree of difficulty the patient has experienced in the last week on a 5-point Likert scale. Each subscale provides a score, which can be calculated to a total score ranging from 0 (worst/extreme difficulties) to 100 (best/ no problems). At least 50% of the questionnaire items in each subscale are required to be answered to permit calculation of a mean score.

At baseline the patient's perception of his or her overall functional ability will be assessed using a single numeric rating scale, as recommended by OARSI. The patient will be asked a single question: "How would you rate your current level of function during your usual activities of daily living?" During follow-up assessment patients will be asked the same question as at baseline. Their answer will be rated on a 0-100 visual rating scale with end-points anchored as "Inability to perform any daily activities" (0) and "No problem with any daily activity" (100)

Performance-based assessment will be performed using the 30-s chair-stand test, which represent the sit-to-stand activity. The test counts the number of sit-to-stand repetitions the patient can perform in 30 seconds. The straight-back chairs used for testing during all outcome assessments will be of the same model, same height (approximately 43 cm), and will be placed against a wall. Any other adaptations (i.e. the use of armrests or assistive devices) will be reported. To assure understanding, two slow-paced repetitions will be practiced before the test initiates. The 30-s chair stand test has proven good reliability to measure functional performance following THA and TKA.

This performance-based assessment measures short distance walking activity. The patient will be instructed to walk as quickly as safely as possible to a mark 10 meters away, return and repeat for a total distance of 40 meters. Each walk of 10 meters (excluding the turn time) is recorded and expressed as speed m/s by dividing distance by time in seconds. A practice walk up and back will be performed to assure understanding. Any assistive devices used will be recorded.

The use of analgesics will recorded at baseline and at all follow-up assessments, using a nominal scale (yes/no) regarding the daily consumption of opioids, non-steroid-anti inflammatorily drug (NSAID) and paracetamol. If the patient were not aware of his or hers use of analgesics, a medical record will obtained to assess the use of analgesics.

The type (e.g. elbow crutches, walker) will be recorded. The need for walking assistant devices will be assessed by what the patient use during normal activities of daily living.

Patients will be asked to answer four questions to indicate their level of satisfaction. The answers will be based on a 4-Likert ordinal scale with the categories: very satisfied (100 points), somewhat satisfied (75 points), somewhat dissatisfied (50 points), and very dissatisfied (25 points). The score is the unweighted mean of the combined scores. The four questions are: "How satisfied are you with the results of your surgery and rehabilitation?", "How satisfied are you with your surgery and rehabilitation for improving your pain?", "How satisfied are you with the results of your surgery and rehabilitation for improving your ability to do home or yard work?" and "How satisfied are you with the results of surgery and rehabilitation for improving your ability to do recreational activities?". The questions are modified from the Self-Administered Patient Satisfaction Scale for Primary Hip and Knee Arthroplasty.

Analysis of the economical resources required for each of the three rehabilitation strategies. The principal investigator intend to use this data in a later cost-analysis.

Number and nature of adverse events during enrolment of the trial will be recorded, regardless of the relation to the trial.

Exercise adherence will be measured as a self-reported percentage (0-100), where 0 % indicates total non-adherence and 100 % indicates total adherence to the exercise prescription. The patients will be asked: "What percentage of the prescribed 42 exercise sessions (one exercise session per day for 6 weeks; corresponding to 100 %) have you completed the past 6 weeks?". The scale will be illustrated with a 0-100mm visual rating scale.