[Reduction of Muscle Atrophy after Anterior Cruciate Ligament Reconstruction]

Thigh muscle atrophy is a consistently reported complication following anterior cruciate ligament (ACL) reconstruction. Poor postoperative muscle status is associated with inferior functional outcomes and an increased risk of re-injury.

This narrative review is based on a systematic literature search in PubMed and Cochrane investigating pre-, intra-/perioperative, and postoperative interventions, as well as adjunctive measures (nutrition, supplementation) aimed at reducing muscle atrophy following ACL reconstruction.

Several factors and interventions can reduce post-reconstruction muscle atrophy. Preoperatively, the timing of surgery (21-100 days after injury) and structured prehabilitation are essential. Intraoperatively, tourniquet use increases early postoperative atrophy without affecting long-term outcomes; femoral nerve block should be avoided. Graft choice has a substantial impact on the risk of muscle atrophy (quadriceps tendon > patellar tendon > hamstring tendon). Postoperatively, progressive eccentric resistance training and early neuromuscular electrical stimulation (NMES) are most effective interventions, while blood flow restriction training (BFRT) is a promising adjunctive strategy. Nutritional optimization (≥ 1.6-1.9 g protein/kg/day) and perioperative supplementation with essential amino acids (EAAs) and β-hydroxy-β-methylbutyrate (HMB) have demonstrated beneficial effects, particularly in high-risk patients.

Muscle atrophy following ACL reconstruction is unavoidable but can be substantially reduced through a multimodal perioperative approach. In particular, high-risk patients are likely to benefit from the consistent combination of all available preventive strategies.