Background: Blood flow restriction training (BFR-t) data are heterogeneous. It is unclear whether rehabilitation with BFR-t after an anterior cruciate ligament (ACL) injury is more effective in improving muscle strength and muscle size than standard rehabilitation.
Purpose: To review outcomes after an ACL injury and subsequent reconstruction in studies comparing rehabilitation with and without BFR-t.
Study design: Systematic review. Level of evidence, 3.
Methods: A search of English-language human clinical studies published in the past 20 years (2002-2022) was carried out in 5 health sciences databases, involving participants aged 18-65 undergoing rehabilitation for an ACL injury. Outcomes associated with muscle strength, muscle size, and knee-specific patient-reported outcome measures (PROMs) were extracted from studies meeting inclusion criteria and compared.
Results: The literature search identified 279 studies, of which 5 met the selection criteria. Two studies suggested that BFR-t rehabilitation after an ACL injury improved knee or thigh muscle strength and muscle size compared with rehabilitation consisting of comparable and higher load resistance training, with two studies suggesting the opposite. The single study measuring PROMs showed improvement compared to traditional rehabilitation, with no difference in muscle strength or size.
Conclusion: BFR-t after an ACL injury seems to benefit muscle strength, muscle size, and PROM scores compared with standard rehabilitation alone. However, only 1 large study included all these outcomes, which has yet to be replicated in other settings. Further studies utilizing similar methods with a common set of outcome measures are required to confirm the effects of BFR-t on ACL rehabilitation.
Keywords: anterior cruciate ligament; blood flow restriction; muscle physiology; physical therapy.