Effectiveness of an interactive telerehabilitation system with home-based exercise training in patients after total hip or knee replacement: study protocol for a multicenter, superiority, no-blinded randomized controlled trial

In this multicenter, no-blinded, parallel-group randomized controlled trial, patients after hip or knee replacement with a subsequent orthopedic rehabilitation are enrolled in the three participating inpatient rehabilitation centers in Germany. In this study, blinding was not possible due to the nature of the intervention. Assessments are carried out by research associates of University Outpatient Clinic of the University of Potsdam (study site), who are also responsible for giving out the telerehabilitation system to the patients of the intervention group.

The patients are either randomized into the intervention or the control group, using a block randomization with a ratio of 1:1, stratified by the inpatient rehabilitation center. The random code was prepared by the statistical institute in advance and is centrally managed by the study site. The patients are investigated and assessed at the study site within 7 days after their inpatient rehabilitation (Fig. 1).

Patients are eligible for inclusion if a total hip or knee replacement after idiopathic, posttraumatic or congenital osteoarthritis was implanted, they are aged between 18 and 65 years and insured by the German Pension Insurance. Patients without expected functional safety in walking with full load at the end of the rehabilitation are excluded. For those patients, it is assumed that they are not able to perform exercises with adequate load and assessments at the study site. Insufficient skills of the German language in speech and writing also lead to exclusion. For the use of the telerehabilitation system at home, some additional criteria (e.g., High Definition Multimedia Interface (HDMI)-compatible screen, minimum 2.5 m space in front of the screen and Internet access) are required.

The study is conducted in accordance with the principles stated in the Declaration of Helsinki and Good Clinical Practice (International Conference of Harmonization). The study protocol was approved by the Ethics Committee of the University of Potsdam (No. 15/2016) and registered at the German Clinical Trials Register (DRKS00010009). The Standard Protocol Items: Recommendations for Interventional Trials (SPIRIT) checklist is available as an additional file (Additional file 1).

Data protection rules are closely observed and patient data are processed anonymously. All data are documented in paper and pencil form. Before the study, all assessments were determined in a standard operating procedure document including step-by-step instructions to promote data quality. For this purpose, every member of the staff was trained in advance. All data are entered electronically by a research assistant at the study site. The data entry file resembles the data collection paper form and contains programmed plausibility checks including referential data rules, valid value checks as well as range checks. Several research associates control the data independently.

All patients undergo a subsequent 3- to 4-week, inpatient, orthopedic rehabilitation program in one of the three participating centers. The program starts within 14 days after surgery. The main components of the multidisciplinary therapy elements are exercise training and physiotherapy, training in activities of daily living, patient education, nutrition and psychological counselling as well as social support to increase patients’ ability to return to work [4]. Patients randomized into the intervention group have two additional 1-h educational sessions with a trained physiotherapist to become familiar with the telerehabilitation system. The latter took part in a structured “train-the-trainer” program in advance which included how to use the system, how to instruct the patients and how to supervise and monitor the intervention. During rehabilitation, potential confounding variables like 6-minute walk distance (6MWD) and range of motion of the joint are documented at admission and at discharge of rehabilitation.

The intervention consists of a 3-month, interactive telerehabilitation with home-based exercise training and is based on the system MyRehab®. It starts within 7 days after discharge from inpatient rehabilitation.

The individually tailored exercise training regarding the choice of exercises (38 different strength and balance exercises) and training modalities (number and sets of repetitions as well as duration of resting time) is created and monitored by the responsible physiotherapist in the rehabilitation center. The patient is instructed to exercise 3 to 4 times a week. The physiotherapist and the patient are always able to communicate via text or voice messages and a video-conference is scheduled on a weekly basis.

The exercises are shown on a screen and the patient is instructed to perform the exercises simultaneously with the system. While exercising, the patient is recorded by a video camera. By tracking the movement pattern, the patient receives an automatic real-time motion feedback in the form of green and red coloration of the single body segments for correct and incorrect movements, respectively. After each exercise, the patient gets a grade evaluating the quality of each exercise as well as the whole training, which can also be seen and interpreted by the physiotherapist in the rehabilitation center for further adjustment of the exercise training.

Patients in the intervention group are allowed to use additional, voluntary, usual aftercare programs, such as exercise-based group training, individualized exercise training or physiotherapy, or to exercise on their own. All performed training options including frequency and duration are recorded in a personal training diary.

Patients randomized into the control group receive voluntary usual care after their inpatient rehabilitation which includes the usual aftercare programs, such as exercise-based group training, individualized exercise training or physiotherapy, or to exercise on their own. Everything is also recorded in a personal training diary. To promote patient retention, especially in the control group, patients are offered an evaluation of their investigations at the study site. Additionally, all patients receive a phone call 1 week before follow-up.

During the baseline visit, sociodemographic (e.g., age, sex, weight, gender, educational level and work ability) and clinical data (e.g., risk factors, comorbidities, pain medication and data of surgery) are documented. Furthermore, the following assessments are performed at baseline and at follow-up 3 months later: functional assessments such as the 6-minute walk test (6MWT) [20] for physical capacity, the Timed Up and Go Test (TUG) [21], the Stair Ascend Test [22], the Five-Times-Sit-to-Stand Test [23] for balance, strength and mobility, the questionnaires Short Form 36 (SF-36) [24] for health-related quality of life, International Physical Activity Questionnaire (IPAQ) [25] for the level of physical activity and the Western Ontario and McMaster Universities Arthritis Index (WOMAC) [26] for pain and stiffness. Measures of function include the assessment of the postural control during double-footed and one-leg stance [27] for left and right leg (barefoot, hands to the hip, view straight forward) for 30 s on a force plate (Amti OR6-6, Advanced Mechanical Technology, Inc. Watertown, MA, USA) as well as gait analysis during over-ground walking (10 trials) with self-selected velocity using a 3D-motion analysis system (12 cameras, Vicon MX; 200 Hz; Vicon Ltd., Oxford, UK) and a kinematic Plug-in Gait lower body model (Vicon Nexus) [28] (see Fig. 2 for the Standard Protocol Items: Recommendations for Interventional Trials (SPIRIT) Figure that the trial follows). Additionally, adverse events (e.g., wound infection, joint luxation) will be documented and evaluated. Further adverse events are not expected due to the constitution of the patients after the inpatient rehabilitation.

The primary outcome is the difference in enhancement of the 6MWD between intervention and control group in meters after 3 months. The 6MWT is an objective assessment [20] that has been found to detect functional improvement after total hip and knee replacement [29‐32].

To provide a comprehensive comparison between the two groups, a battery of questionnaires, functional and measures of function will also be investigated:

Data will be evaluated descriptively (mean, standard deviation, 95% confidence interval and median for metric variables, frequency and percentiles for categorical variables) for all variables as available case analysis. Inferential statistics will be performed using an intention-to-treat approach including all randomized patients and with multiply imputed data sets for evaluation of the effectiveness of the intervention, as well as a per-protocol approach in patients with complete data sets and without protocol violations for evaluation of the efficacy of the intervention. Baseline-adjusted analysis of covariance (ANCOVA) models (intention-to-treat) will be used to test the primary endpoint for group differences at a level of 5% (two-sided). All continuous secondary endpoints will be analog-tested without adjustment for multiplicity. The rates of return to work status will be compared with the Likelihood-Ratio-Chi²-Test. Model assumptions will be checked by testing site × group interactions as extensions of the analysis of covariance (ANCOVA) models.

According to Boardman et al. [30], an improvement of 65–70 m in 6MWD is to be expected by knee or hip replacement followed by standard orthopedic rehabilitation. The study was powered to be able to demonstrate a further improvement of 65 m by telerehabilitation as compared to an improvement of not more than 13 m (20%) in the control group. Assuming an intraclass correlation of 0.3 for the primary outcome and a standard deviation of 84 m [30, 33], 42 patients per group will be needed to reach a power of 80% for the primary analysis. Presuming a 20–25% loss to follow-up, 55 patients per group need to be included in the study to reach the same power in the per-protocol analysis, resulting in a recruitment and randomization of 110 patients in total.