In this study we will investigate the relation between performed exercise dose and recovery after total hip replacement (THA). A dose-response relationship is hypothesized. It is the primary objective to indicate the preliminary efficacy of home-based rehabilitation using elastic band exercise on performance-based function after THA, based on the relationship between the performed exercise dose (objectively quantified time under tension summary dose) and the change in 40 meter maximal gait speed (performance-based function) from 3 (start of intervention) to 10 weeks (end of intervention) after surgery.
The study is a pragmatic, single center, prospective cohort study (single cohort) to be conducted in Silkeborg, Denmark. The outcomes will be collected in the period from 3 to 10 weeks after surgery by an assessor blinded to exercise compliance. The study will adhere methodologically to the STROBE guidelines and checklist for prospective cohort studies (www.strobe-statement.org). The study design and completion is conducted in a research collaboration between the Interdisciplinary Research Unit at Elective Surgery Centre based at Silkeborg Regional Hospital and Physical Medicine \& Rehabilitation Research - Copenhagen (PMR-C) based at Hvidovre Hospital. Primary objective, eligibility criteria, exposure/intervention and outcome measures are entered elsewhere. At June 28, 2017, two outcome measures were added to the study. At 10 weeks after surgery, patients will be asked both to describe change in hip problems (from preoperatively to 10 weeks after surgery) and to describe their perception of outcome after surgery. The outcome measures will be used for exploratory analysis of patient acceptable symptom state (PASS) and minimal clinically important improvement (MCII) Primary analysis: A simple linear regression analysis will be performed to evaluate the association between performed exercise dose and change in score on gait speed. Furthermore descriptive statistics will be used to quantify exercise compliance and to indicate the exercise dosage with the greatest response. Patients will be divided into four compliance-quartiles and summary statistics of the primary outcome (change in gait speed) will be presented graphically to illustrate possible dose-response relationship. Secondary analyses: For change in patient-reported function the analysis will be similar to the analysis for change in gait speed. Summary statistics on the rest of the secondary outcomes will be presented for the compliance-quartiles. In a multiple regression analysis the association between gait speed (at 10 weeks follow up) and self-efficacy, 24-hour physical activity, performed exercise dose and gait speed (at baseline) will be analyzed. Furthermore summary statistics will be presented for demographic data and other pre-specified outcomes. Additionally, an embedded qualitative study will be performed to explore motivation and barriers related to exercise compliance. This study will be reported in a secondary paper with a clear reference to the primary trial and trial registration. Regional Hospital Central Jutland and The Danish Rheumatism Association is partly funding the salary for physiotherapists involved in the study. Further external funding will be applied for.
The intervention reflects the standard rehabilitation practice at Elective Surgery Centre. 3 weeks after surgery the patients will receive a thorough instruction and supervision in the strength training exercises that they are to perform without supervision at their own homes the following 7 weeks. The instruction is conducted one-to-one by physiotherapists and supported by an instruction booklet with written and illustrated exercise descriptions. The exercises included are: hip abduction, flexion and extension with elastic band resistance and sit-to-stand and one-legged stance. The prescribed training load will be two sets with repetitions to failure and a relative load of 10 to 20 RM (Repetition Maximum), performed every second day (3-4 times a week). Exposure: Performed exercise dose will be quantified as the total physiological exercise stimulus (Time under tension summary dose) recorded by a sensor (BandCizer) attached to the elastic exercise band.
Silkeborg Regional Hospital
Silkeborg, Denmark
Change in gait speed
Measured by the 40m fast-paced walk test (continous, m/sec)
Time frame: Change from 3 to 10 weeks after surgery.
Gait speed
Measured by the 40m fast-paced walk test (continous, m/sec)
Time frame: 10 weeks after surgery
Change in patient-reported function
Measured by the ADL (Activities of Daily Living) subscale of Hip disability and Osteoarthritis Outcome Score (HOOS). HOOS is a disease-specific patient-reported outcome measure (continous)
Time frame: Change from 3 to 10 weeks after surgery.
Change in patient-reported symptoms
Measured by the symptoms subscale of HOOS (continous)
Time frame: Change from 3 to 10 weeks after surgery.
Change in patient-reported pain
Measured by the pain subscale of HOOS (continous)
Time frame: Change from 3 to 10 weeks after surgery.
Change in patient-reported hip related quality of life
Measured by the quality of life subscale (QoL) of HOOS (continous)
Time frame: Change from 3 to 10 weeks after surgery.
Change in lower-extremity function
Measured by the Chair stand test (The maximal number of rises from a chair within 30 seconds) (continous)
Time frame: Change from 3 to 10 weeks after surgery
Change in hip abductor muscle strength
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Study Type
OBSERVATIONAL
Enrollment
94
Test of isometric muscle strength in hip abduction in the operated leg. The hand-held dynamometer Power Track II Commander will be used to assess this using standardized test procedures (continous, Nm/kg)
Time frame: Change from 3 to 10 weeks after surgery
Change in hip flexor muscle strength
Test of isometric muscle strength in hip flexion in the operated leg. The hand-held dynamometer Power Track II Commander will be used to assess this using standardized test procedures (continous, Nm/kg)
Time frame: Change from 3 to 10 weeks after surgery
Self-efficacy
The general self-efficacy scale will be used to measure self-efficacy, defined as an individual's belief in his or her capacity to execute behaviors necessary to produce specific performance attainments (continous)
Time frame: 3 weeks after surgery
24-hour physical activity (mean upright time).
An ActivPAL movement-sensor will be used to measure mean time per day in upright position (standing and walking) based on 7 days of data collection. The sensor will be applied 3 weeks after surgery and used the following week (continous, min/day)
Time frame: 4 weeks after surgery
24-hour physical activity (mean number of steps)
An ActivPAL movement-sensor will be used to measure mean number of steps per day based on 7 days of data collection. The sensor will be applied 3 weeks after surgery and used the following week (continous, min/day)
Time frame: 4 weeks after surgery