Sequential Damage Assessment of the Posterolateral Complex of the Knee Joint: A Finite Element Study

Background. The posterolateral complex (PLC), which consists of the popliteus tendon (PT), lateral collateral ligament (LCL), and popliteofibular ligament (PFL), is an indispensable structure of the knee joint. The aim of this study was to explore the functionality of the PLC by determining the specific role of each component in maintaining posterolateral knee stability. Methods. A finite element (FE) model was generated based on previous material property data and magnetic resonance imaging of a volunteer’s knee joint. The injury order of the PLC was set as LCL, PFL, and PT. A 134 N anterior load was applied to the tibia to investigate tibial displacement (TD). Tibial external rotation (TER) and tibial varus angulation (TVA) were measured under bending motions of 5 and 10 Nm. The instantaneous axis of rotation (IAR) of the knee joint under different rotation motions was also recorded. Results. The TD of the intact knee under a 134 N anterior load matched the values determined in previous studies. Our model showed consistent increases in TD, TVA, and TER after sequential damage of the PLC. In addition, sequential disruption caused the IAR to shift superiorly and laterally during varus rotation, and medially and anteriorly during external rotation. In the dynamic damage of the PLC, LCL injury had the largest effect on TD, TVA, TER, and IAR. Conclusions. Sequential injury of the PLC caused considerable loss of stability of the knee joint according to an FE model. The most significant structure of the PLC was the LCL.

TÉCNICA DE LARSON ORIGINAL MODIFICADA PARA LA RECONSTRUCCIÓN DEL LIGAMENTO COLATERAL LATERAL DE LA RODILLA, REPORTE DE UN CASO.

The lateral collateral ligament (LCL), which is part of the knee stabilizers, constitutes an important structure within the posterolateral complex of the same (CPL), which restricts the varus, in the flexion angles of this, especially at 30°, in addition to controlling external rotation. Lesions that affect this complex are infrequent, etiologically between 50-90% are associated with other ligamentous injuries with a predominance of 60% damage to the posterior cruciate ligament. The Larson technique is based on the reconstruction of the LCL and the popliteal complex, using a single proximal insertion in the femoral epicondyle.We present the case of a 28-year-old male patient, with no medical history, who attended due to a forced varus of the limb while performing sports activity and after receiving a direct impact on the internal lateral region of the right calf, after which he presented pain to passive movements and inability to ambulation. In addition, he presents ecchymosis, edema, superficial abrasions on the external lateral aspect and pain on acupressure in the course of the external collateral ligament. A knee examination maneuvers: positive varus yawn sign, positive patellar brushing, positive patella hyperpressure, functional limitation to flexion and extension of the joint.This modified Larson technique turns out to be one of the most promising due to its various characteristics, as the least demanding and at the same time providing encouraging results. This procedure is based on the reconstruction of the LCL and the popliteal tendon (PT) as a whole, thus summarizing the reconstruction of the Peroneal Popliteal Ligament (LPP) as a static stabilizer of the PT, with its insertion at the level of the head of the fibula in conjunction with the of the LCL and the restitution of both attachments in the femoral epicondyle, taking into account the morphology of the fibula and the angles of movement of the knee.

Clinical Outcomes of Posterolateral Complex Reconstruction Performed with a Single Femoral Tunnel

The objective of this study is to report the functional outcomes, complications, and reconstruction failure rate of patients undergoing posterolateral complex reconstruction with a single femoral tunnel technique. Patients with posterolateral complex injuries associated with injury of the anterior cruciate ligament (ACL), posterior cruciate ligament (PCL), or both undergoing surgical treatment with the single femoral tunnel technique were included in the study. The International Knee Documentation Committee (IKDC) and Lysholm's scales were evaluated, in addition to age, gender, time between trauma and surgery, trauma type, range of motion (ROM) restrictions, peroneal nerve injury, and reconstruction failure. Sixty-six patients were included. Eighteen underwent ACL and posterolateral complex (PLC) reconstruction (group 1), 24 underwent ACL, PCL, and PLC reconstruction (group 2), and 24 underwent PCL and PLC reconstruction (group 3). The mean follow-up was 63 months. The subjective IKDC was 83.7 ± 14.6 for group 1, 74.3 ± 12.6 for group 2, and 66.3 ± 16.0 for group 3 (p < 0.001). The Lysholm's score was 87.1 ± 12.8 for group 1, 79.5 ± 15.0 for group 2, and 77.7 ± 15.2 for group 3 (p = 0.042). There were six reconstruction failures among the patients (9.1%) with no differences among the groups (p = 0.368). Female gender and reconstruction failure were associated with worse outcomes. Patients undergoing reconstruction of PLC structures with the single femoral tunnel technique achieved good functional outcomes and a failure rate similar to literature. Patients undergoing only combined ACL reconstruction showed better outcomes than patients undergoing combined PCL reconstruction. Female gender was associated with a worse functional outcome irrespective of the injury type.