Late-initiated Blood Flow Restricted Rehabilitation Exercises After Total Knee Replacement

This trial will investigate the effectiveness of applying low-load blood flow restricted exercise 12 months after receiving a total knee replacement to achieve a functional capacity-level similar to healthy peers. Participants will be allocated to either an exercise group performing a sit-to-stand exercise 4/weekly with concurrent partial restriction of the blood flow to the limbs or a usual care.

Blood flow restricted exercise (BFRE) is resistance training with low loads (30% 1repetition maximum (RM) performed with concurrent partial blood flow restriction by means of pneumatic cuff compression around the working limb.

Group 1:

BFRE group: After being introduced to the exercise principles, the participants will perform 4/weekly home-based BFRE sessions for 12 weeks from. Each session will consist of a sit-to-stand exercise performed with concurrent partial restriction of the blood flow to the limbs. The exercise consist of 4 rounds interspaced by 30 seconds of rest. 1st round: 30 repetitions (reps); 2nd round: 15 reps; 3rd round: 15 reps; 4th round: until exhaustion. Patients will rest in a standardized resting position between each set to maintain the desired resting cuff-pressure.

The occlusion pressure will be set at 60% of total limb occlusion pressure and starting load intensity will be 30% 1repetition maximum (1RM) in both exercises. If patients can perform more than 15 repetitions in the 4th exercise set, more external resistance will added at the next session.

Group 2:

CON group: Will follow standard procedures 12 months after total knee replacement.

The trial is designed as a multicenter (two sites) randomized controlled trial. The primary outcome, Timed Up and Go, as well as all secondary outcomes measured at end of intervention.

The patients in the present project will be recruited from the patients in Jorgensen et al. (1) who have either performed 8 weeks of preoperative BFRE (PREBFR), received usual care prior to total knee replacement (TKR) (PRECON), or participated in the cohort-study. Further, exclusion criteria will remain the same as in Jorgensen et al. (1).

before, enrollment all patients will be re-screened for eligibility by the principal author (SLJ) who will perform the inclusion of patients and provide oral and written project information. All patients accepting to participate will sign a written informed consent to participate in the project. All patients who have participated in the randomized controlled trial will be offered 12 weeks of home based BFRE, while all subject who have participated in the cohort-study will be invited to serve as a control group

Patients in the home based BFRE group will be carefully instructed in how to perform the BFRE exercises at home.

The aim of the current study is to investigate the effectiveness of 12 weeks of BFRE homed-based exercises initiated 12 months after TKR. Furthermore, we will determine if patients who have performed 8 weeks of preoperative BFRE profits more from the late initiated BFRE program compared to patients who have not received 8 weeks of preoperative BFRE.

All descriptive statistics and tests will be reported in accordance with the recommendations of the "Enhancing the QUAlity and Transparency Of health Research" (EQUATOR) network and the CONSORT statement. Intention-to-treat principle (i.e. all patients as randomized independent of departures from allocation treatment, compliance and/or withdrawals) and per protocol analysis will be conducted. A one-way analysis of variance (one-way ANOVA) model will be used to analyze between mean change in continuous outcome measures between the group of patients who have performed 8 weeks of preoperative BFRE (PREBFR) and the group who did not perform 8 weeks of preoperative BFRE (PRECON) (27). The model includes changes from baseline to end of intervention. Also, to gain insight into the potential pre-to-post training differences within the whole patient population (PREBFR+PROCON), the PREBFR-patients and the PRECON-participants, paired student t-tests will be performed. Level of statistical significance is P \< 0.05.

Eligibility Criteria:
Inclusion Criteria:

* Patients included in the EXknee project (Efficacy of low-load blood flow restricted resistance EXercise in patients with Knee osteoarthritis scheduled for total knee replacement (EXKnee) Jorgensen et al. 2020)

Exclusion Criteria:

* Severe cardiovascular diseases (New York Heart Association class III and IIII), -
* previous stroke incident, thrombosis incident
* Traumatic nerve injury in affected limb
* Unregulated hypertension (Systolic ≥180 or diastolic ≥110 mmHg)
* Spinal cord injury
* Cancer diagnosis and currently undergoing chemo-, immuno-, or radiotherapy
* Inadequacy in written and spoken Danish
* living more than 45 minutes from either Horsens Regional Hospital or Silkeborg Regional Hospital.