Revista de Medicina Desportiva (English) November 2018 - Page 20

Rev. Medicina Desportiva informa, 2018; 9(6):18-22. Injuries to the Posterior- Lateral Corner of the Knee Dr. Carlos Mesquita Queirós 1 , Dr. Alcindo Silva 2 1 IResident on Orthopedics at the Centro Hospitalar Entre Douro e Vouga, Santa Maria da Feira; 2 Orthopedic and Traumatology Specialist Hospital da Luz Arrábida, V N Gaia RESUMO / ABSTRACT Posterolateral corner lesions of the knee occur frequently alongside other ligament lesions, and are amongst one of the major causes of failure in anterior cruciate ligament reconstructions and degenerative arthritis. Anatomical and biomechanical research reveals the importance of three lateral strutures: lateral collateral ligament, popliteus muscle, and poplitealfibular ligament. For accurate diagnosis the physical examination, the stress radiographs and the MRI are indispensable. Treatment of high-grade lesions should be surgical, with improved clinical outcomes reported by anatomical techniques. Injury PALAVRAS-CHAVE / KEYWORDS Knee, posterolateral corner, posterolateral reconstruction, lateral instability knee Introduction It is historically referred as the obscure side of the knee, the pos- terior-lateral corner (PLC) has been subject of renovate attention. The injuries of the PCL are quite often associated to other ligament injuries and they are noxious if not timely recognized, being one common cause of failure after anterior cruci- ate ligament (ACL) reconstruction and also mechanical changes in the knee with subsequent early articular degeneration. 1-5 To identify these injuries there should be a high suspicion and a strict and systematic physical exam is needed. To find the injured struc- tures it is indispensable the detailed evaluation of the complementary diagnostic exams, like the X-ray and the magnetic resonance (MRI). 6,7 The conservative treatment for the high degree injures doesn’t have satisfactory results 8 , which has been recently motivating the description of several techniques for reconstruction. In this paper it will be reviewed the surgical anatomy of the PLC, the clinical diagnosis, the image study and the treatment. Anatomy The most important structures for lateral stabilization are deeper 18 november 2018 www.revdesportiva.pt in relation to the femur. In case of insufficiency of the cruciate liga- ments, this structure also provides secondary stabilization to the poste- rior and anterior translation. 11,12 The LCL is the primary restrictor to the varus forces and all other struc- tures act as secondary restrictors. 4,14 In relation to the external rotation, the principal restrictors are the LCL and popliteus complex (PPL and the popliteus tendon). The PCL acts as secondary restrictor. 14-17 Both in the internal rotation and on anterior-posterior stabilization, the PLC has a secondary role with functioning cruciate ligaments. 4,14,15 located, like the lateral collateral lig- ament (LCL), the popliteus-peroneal ligament (PPL) and the popliteus tendon. 12 The LCL is the primary stabilizer for the varus forces. 4,14,15 It originates in a proximal and small cavity posterior to the lateral epicon- dyle, runs under the iliotibial band and the femoral biceps tendon to its insertion on the lateral aspect of head of the fibula. 9,16 The popliteus muscle originates at the posterior-lateral area of the tibia, runs proximally and laterally to the insertion on the popliteus sulcus of the femur. The fact that the average distance between its insertion and the one of the LCL is 18,5mm has clinical importance, since due to this difference a unique femoral graft can not reproduce the tensioning at different angles of flexion (Figure 1). 9,16 The PPL is an important stabilizer to the external rotation and second- ary restrictor to the varus forces in the knee. It is a fibrous structure that connects the popliteus tendon to head of the fibula (Figure 2). 9 It is a high-energy injury and it is associated with high-impact sports, where the most probable cause is the combination of a direct force applied to the medial face of the tibia, applied posterior-lateral, with extension of the knee. 18 There are frequently associated severe liga- ment injuries, like knee dislocation. 18 The injuries on the PLC are rarely isolated, although in the majority of the cases they are associated to the PCL. On meta-analysis published with 456 patients there were 12% of isolated injuries, 23% with rupture of the ACL, 59% with the PCL and in 6% with the PCL and ACL. 19 Diagnosis The injury can be detected on the acute or chronic phases. Clinically, on the acute phase, the patients have pain, lateral exuberant edema Biomechanics The biomechanics role of the posterior cruciate ligament (PCL) consists on the restriction to the primary varus forces and also to the posterior-lateral rotation of the tibia Figure 1 – The principal stabilizers of the posterior-lateral corner https://ars.els-cdn.com/content/image/1-s2.0- S010236161400277X-gr1.jpg