Anterior Cruciate Ligament Injury and the Anterolateral Complex of the Knee—Importance in Rotatory Knee Instability?

Abstract

Purpose of Review In the setting of rotatory knee instability following anterior cruciate ligament (ACL) reconstruction, there has been a resurgence of interest in knee's anterolateral complex (ALC). Reconstruction or augmentation of the ALC with procedures such as a lateral extra-articular tenodesis (LET) has been proposed to reduce rotatory knee instability in conjunction with ACL reconstruction. The current review investigates the recent literature surrounding the role of the ALC in preventing rotatory knee instability. Recent Findings The knee's anterolateral complex (ALC) is a complex structure composed of the superficial and deep portions of the iliotibial band, the capsulo-osseous layer, and the anterolateral capsule. Distally, these various layers merge to form a single functional unit which imparts stability to the lateral knee. While the iliotibial band and the capsule-osseous layer have been shown to be primary restraints to rotatory motion after ACL injury, the biomechanical role of the anterolateral capsule remains unclear. Biomechanical studies have shown that the anterolateral capsule and the anterolateral thickening of this capsule act as a sheet of fibrous tissue which does not resist motion around the knee as other longitudinally oriented ligaments do. Summary Augmentation of the ALC, with LET, has been performed globally for over 30 years. This procedure can decrease rotatory knee instability, but long-term studies have found little difference in patient-reported outcomes, osteoarthritis, or ACL reconstruction failure with the addition of LET. Further research is needed to clarify indications for the clinical use of ALC-based procedures.

Injuries to the anterolateral ligament are observed more frequently compared to lesions to the deep iliotibial tract (Kaplan fibers) in anterior cruciate ligamant deficient knees using magnetic resonance imaging

“…Besides numerous studies analyzing the ALL, little knowledge exists about the injury incidence of the deep portion of the ITT. This is somewhat surprising, since those structures have been described anatomically much earlier than the ALL, are believed to work as an agonist to the ACL (like a horseshoe) and are emphasized by some authors to play a more important role than the ALL in providing anterolateral rotatory stability [10, 20, 22, 29, 34, 49]. Batty et al [2] examined 50 healthy knees using MRI and identified the dITT in 96% of the cases on sagittal images and 76% in the axial view.…”

High Prevalence of Persistent Measurable Postoperative Knee Joint Laxity in Patients with Tibial Plateau Fractures Treated by Open Reduction and Internal Fixation (ORIF)

“…When it comes to persistent anterolateral rotatory laxity (ALRL), the anterolateral complex (ALC), involving the iliotibial band with its three layers, the accompanying Kaplan fibers, and the anterolateral ligament, has been effectively shown to offer resistance against internal rotational torques, particularly at greater levels of knee flexion [38][39][40][41][42][43][44]. As the tibial insertion of these structures is located at Gerdy's tubercule or slightly posterior to it [38,41,43,45], it is in conflict with the standardized anterolateral approach to the tibial plateau.…”