Editorial Commentary: Failure to Regain Full Hyperextension After Anterior Cruciate Ligament Reconstruction Is Associated With Inferior Patient Satisfaction and Lower Functional Outcomes Scores, But the Impact on Graft Rupture Rates and Persistent Instability Is Unclear.

Up to one half of patients undergoing anterior cruciate ligament reconstruction demonstrate some degree of knee hyperextension in their contralateral limb. In most cases, this is mild (1°-5°), but it is reported that 9% and 0.8% demonstrate moderate (6°-10°) and severe (>10°) degrees of hyperextension. These characteristics pose challenges and considerations for surgical management. This includes the finding that failure to regain full hyperextension is common and is associated with inferior functional outcomes and patient satisfaction, and the juxtaposition that regaining full hyperextension may increase graft rupture and persistent instability rates. Although the pathophysiology of extension deficit is multifactorial, 2 particularly important and modifiable risk factors in this population are notch impingement and arthrogenic muscle inhibition. Strategies to avoid notch impingement include anterior notchplasty and careful consideration of graft size, graft type, and tibial tunnel placement. Arthrogenic muscle inhibition is clinically characterized by extension deficit and quadriceps activation failure. It is reversible in most patients and therefore an important modifiable risk factor. Since failure to regain full hyperextension is associated with inferior outcomes, abolishing extension deficit should be a key objective of surgical treatment and rehabilitation. Concerns regarding the risks of persistent laxity and graft rupture in knee hyperlaxity/hyperextension patients can be mitigated by the addition of anterolateral ligament reconstruction.