# Effect of blood flow restriction training in early postoperative rehabilitation after ACL reconstruction: a randomised controlled trial

## TL;DR

This study found that adding blood flow restriction to low-load strength training after ACL surgery does not offer extra benefits compared to low-load training alone in the early recovery phase.

## Contribution

The study is the first to investigate BFR training's efficacy in early postoperative ACL rehabilitation through a randomized controlled trial.

## Key findings

- No significant differences were found between BFR and low-load training alone in pain or functional outcomes.
- Both groups showed significant improvements in pain, strength, and range of motion over time.
- BFR did not provide additional clinical benefits in the early postoperative phase.

## Abstract

Anterior cruciate ligament (ACL) injuries represent the most prevalent type of knee injury, with surgical reconstruction being the prevailing treatment modality. However, postoperative pain and muscle weakness are common occurrences. Blood flow restriction (BFR) training has demonstrated potential in enhancing muscle adaptation and reducing pain; nevertheless, its efficacy in the early postoperative period following ACL reconstruction remains to be determined. The present study investigates whether the incorporation of BFR into low-load strength training confers additional clinical benefits in comparison to low-load exercise alone.

A total of 30 patients (24 male, 6 female) with a mean age of 32.3 (± 12.4) years were included in the study. All patients had undergone primary ACL reconstruction with a semitendinosus graft and standardized fixation techniques. They were randomised to receive either low-load strength training with (LL-BFR) or without BFR (LL). The interventions consisted of four sets of leg press exercises (30 repetitions for the first set, 15 for subsequent sets) performed twice a week for four weeks, starting four weeks postoperatively, as an adjunct to standard rehabilitation protocols. The primary outcome measure was pain perception, which was assessed by pressure pain thresholds (PPT) and a visual analogue scale (VAS) for knee pain at rest and during a functional stair-climbing test. We further included strength and functional measurements.

Mixed linear models were employed for the statistical analysis. No statistically significant differences between groups were observed for the primary or secondary outcome measures. Only, significant time effects were found for both groups for subjective pain (rest p < 0.001, stairs p = 0.003); maximum strength (p = 0.002); active (ext. p = 0.035, flex. p < 0.001) and passive range of motion (ROM) (ext. p = 0.029, flex. p < 0.001) on the affected side and International Knee Documentation Committee (IDKC) scores (p < 0.001).

The present study shows that a combination of BFR and low-load strength training does not provide additional clinical benefits to low-load training alone in the early postoperative phase, following ACL reconstruction in our study group. Further research is required to explore the potential efficacy of BFR in specific patient subpopulations, with different training loads or at later stages of rehabilitation.