Introduction

Marked quadriceps weakness has been demonstrated prior to undergoing cartilage restoration procedures, and these deficits often persist postoperatively. Blood flow restriction training (BFRT) continues to gain interest amongst rehabilitation specialists as a novel method to improve quadriceps strength. Blood flow restriction training (BFRT) involves the use of an inflatable cuff applied to the thigh to slow blood flow as subjects exercise with a light weight allowing them to receive the same training benefits as if they were training under high loads. The premise for using BFRT after cartilage procedures was initially based off successful use in healthy populations but more recently in patients knee disorders demonstrating greater strength gains than traditional forms of exercise. There is evidence supporting the premise that BFRT will result in both improved quadriceps and hip strength. This then holds promise as greater muscle strength in turn will result in improved lower extremity biomechanics, improved functional capacity, and an accelerated recovery.

Content

In this presentation, we will discuss the physiologic mechanisms of BFRT. We and others have shown BFRT is able to preferentially improve muscle fiber cross-sectional area, increase satellite cell proliferation and may reduce the extracellular matrix in healthy subjects. We are further motivated by our recently published data in anterior cruciate ligament reconstructed subjects which show that these are the precise properties of muscle that are negatively impacted after the injury and rehabilitation so should be positively altered by BFRT.We have also seen that improved quadriceps strength is associated with reducedfear of re-injury and improved self-reported ability to perform quadriceps-dominant activities such as ascending stairs.

BFRT could potentially benefit those with patellofemoral lesions as well. Increased quadriceps strength has been shown to be protective against patellofemoral cartilage loss as well as less pain and improved function.BFRT may not only result in improved quadriceps strength but also proximal changes in hip strength and muscular characteristics. Hip weakness and increased knee adduction angles increase the forces born by the articular cartilage. Improving quadriceps and hip strength may also be chondroprotective by reducing femoral internal rotation thereby lessening compressive forces borne by the cartilage of the lateral patella and trochlea. BFRT with the cuff placed around the proximal thigh has been demonstrated to improve quadriceps strength but has also resulted in changes proximal to the cuff. In healthy volunteers, thigh girth and hip abduction and external rotation strength have both been shown to have significantly greater improvements following a BFRT program when compared to those that completed the same exercise program without BFRT. In older adults, BFRT has also been demonstrated to increase cross sectional area of the hip adductor and gluteus maximus muscle groups in addition to the quadriceps.

Despite rapid adoption in the clinical setting, there is a great deal of variability in BFRT treatment protocols being used. This variability then results in variable strength gains with BFRT. In a balanced presentation of the literature to date, we will also discuss the treatment protocols that have been the most effective as well as contraindications that must be considered prior to using BFRT.