Restricting Blood Flow May Prevent ACL Surgery Bone Loss

A new study suggests that combining blood flow restriction (BFR) therapy with traditional rehabilitation may slow bone loss following anterior cruciate ligament (ACL) reconstruction surgery.

Researchers at Houston Methodist Hospital (HMH; Houston, TX, USA) conducted a randomized prospective study that involved 23 physically active patients (mean age 23), who were divided into two groups following ACL reconstruction, BFR and control. While both groups received a similar rehabilitation protocol, during select exercises the BFR group worked out with an 80% arterial limb occlusion applied via an automated tourniquet. Bone mineral density, bone mass, and lean muscle mass were measured using dual-energy X-ray absorptiometry (DEXA).

The results revealed that the addition of BFR therapy to standard rehabilitation exercises prevented muscle mass loss in the whole leg and thigh, when compared to rehabilitation alone. The addition of BFR was also observed to minimize bone mineral content loss, preserving bone density in the treated limb compared to standard rehabilitation alone. The DEXA findings coincided with observed functional outcomes in the BFR group. The study was presented at the American Orthopaedic Society for Sports Medicine/Arthroscopic Association of North America (AOSSM/AANA) specialty day, held during March 2019 in Las Vegas (NV, USA).

“Providing BFR as part of the rehabilitation efforts following ACL surgery appears to help preserve the bone, recover muscle loss, and improve function quicker, “said lead author Bradley Lambert, PhD, of the HMH orthopedic biomechanics research laboratory. “While further research is needed to fully illuminate the physiologic mechanisms responsible, these findings likely have wide ranging implications for fields outside of ACL rehab alone, such as injury prevention, age-related muscle and bone loss, military rehabilitation, and potentially space flight.”

The ACL is a broad, thick collagen band that originates on the anterior portion of the femur in the intercondylar notch and inserts on the posterior aspect of the tibial plateau. The ACL guides the tibia through a normal, stable range of motion, along the end of the femur, maintaining joint stability. The ligament unfortunately is poorly vascularized, and thus has no real ability to heal after a complete tear, leading to further destruction of the articular and meniscal cartilage over time.

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