Home-based Rehabilitation Following a Total Hip Replacement

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.

Eligibility Criteria:
Inclusion criteria:

* Above 18 years
* Scheduled for a primary THA, at Elective Surgery Centre, due to osteoarthritis
* Able to understand written and spoken Danish

Exclusion criteria:

* Referral to supervised rehabilitation in the municipality