Purpose: The purpose of this systematic review is to assess whether a standardized dietary supplementation can help to decrease postoperative muscle atrophy and/or improve rehabilitation outcomes in patients who underwent anterior cruciate ligament reconstruction (ACL-R).
Methods: A systematic review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA). MEDLINE, Scopus, and Cochrane Library databases were searched, and articles that examined protein or amino acid, vitamin, or any other type of supplementation in ACL-R were reviewed. Two independent reviewers conducted the search utilizing pertinent Boolean operations.
Results: A total of 1,818 articles were yielded after our database search. Ten studies fulfilled our inclusion criteria and only assessed patients undergoing ACL-R. Four studies assessed protein-based supplementation. One study assessed creatine as a supplement. Four studies assessed vitamin-based supplementation. One study assessed testosterone supplementation. Protein and amino acid supplementation showed potential benefits; multiple authors demonstrated a combination of improved achievement of rehabilitation benchmarks, graft maturation, muscular hypertrophic response, and peak dynamic muscle strength. When looking at creatine, vitamin, or hormone-based protocols, none demonstrated results suggesting these factors may attenuate muscle atrophy after surgery. Vitamin C and E demonstrated potentially increased local inflammation in skeletal muscle, which runs contrary to the belief that antioxidant vitamin-based supplementation may decrease the inflammatory response that plays a role in the post injury/operative period.
Conclusion: Protein-based supplementation may play a role in mitigating muscle atrophy associated with ACL-R, as multiple authors demonstrated a combination of improved achievement of rehabilitation benchmarks, thigh hypertrophic response, and peak dynamic muscle strength. However, based on current literature, it is not possible to recommend a specific protein-based supplementation protocol at this time for patients undergoing ACL-R. Limited evidence suggests no benefit for creatine, vitamin, or hormone-based protocols.
Keywords: ACL; Anterior Cruciate Ligament; Supplement; atrophy; knee; muscle mass; orthopedics; surgery.