Editorial Commentary: Knee Hyperextension Injuries: What Are We Really Diagnosing and How to Solve the Problem?

Knee hyperextension injuries remain a poorly defined entity, often functioning more as a descriptive label than a true mechanistic diagnosis. Rather than representing isolated sagittal-plane events, these injuries reflect the final position of complex multiplanar loading patterns, resulting in highly variable structural damage that frequently extends beyond the cruciate ligaments. Emerging clinical observations suggest that patients with subtle hyperextension mechanisms may present with persistent pain and instability despite largely normal imaging and standard ligament testing. This highlights the potential under-recognition of secondary stabilizers, particularly posterior capsular structures. Biomechanical evidence supports this concept, showing that significant hyperextension requires combined disruption of multiple capsuloligamentous restraints, with the posterior capsule playing a central role. The current literature reinforces this perspective, showing that hyperextension is not the result of isolated ligament failure but rather a combined structural breakdown. Clinically, failure to recognize this complexity may lead to incomplete treatment and suboptimal outcomes. A shift toward mechanism-based understanding, exhaustive clinical examination, systematic imaging evaluation, and integrated classification systems is essential to improve diagnosis and management.