Beyond clinical grading: rethinking arthrogenic muscle inhibition after anterior cruciate ligament reconstruction

Arthrogenic muscle inhibition (AMI) remains a clinically important barrier to recovery after anterior cruciate ligament reconstruction. In their recent retrospective study, Morel et al. identified early preoperative and postoperative correlates of AMI using the clinical SANTI classification. We agree that this classification is practical and reproducible for routine assessment, but we caution against conflating clinical grading with mechanistic phenotyping. In the early phase after anterior cruciate ligament reconstruction, the SANTI classification can help clinicians screen and monitor quadriceps activation failure and extension deficit, yet mechanistic inference requires complementary measures of voluntary activation, such as interpolated twitch techniques or central activation ratio assessment, and, in research settings, corticospinal evaluation with transcranial magnetic stimulation. We also believe that the reported lack of association between pain and AMI should be interpreted cautiously because isolated pain ratings may not capture task-related pain, joint irritability, or guarding during movement. Early management should therefore integrate pain and effusion control, restoration of extension, quadriceps activation, and movement quality rather than address these as separate domains. Clinical grading is valuable for early care, but it should remain distinct from mechanistic explanation. LEVEL OF EVIDENCE: N/A.