New autografts in PLC lesions Oliveira MG et al. Table 1 - The Lysholm scores before and after surgery (paired Student’s t test). Lysholm Before After n 114 114 Mean 46.1 95.7 Standard deviation 6.7 4.5 Median 47.0 99.0 p-value ,0.001 ranged from 2 to 156 months, with a mean time of 26 months and 27 days, a median of 18 days and a standard deviation (SD) of 27.27 days. The chronic lesions of the posterolateral corner of the knee were always associated with at least one lesion of the cruciate ligaments and were distributed as follows: lesions of the anterior cruciate ligament (ACL) in 66 cases, lesions of the posterior cruciate ligament (PCL) in 35 cases and lesions of both the ACL and PCL in 22 cases; ACL lesions and varism in four cases, PCL lesions and varism in one case, and lesions of both the ACL and PCL plus varism in one other patient. Of the 129 treated patients, Lysholm questionnaire results were available for 114 patients at the postoperative evaluation and were significantly different from the preoperative evaluation results (p,0.001), as shown in Table 1. The results of the ligament evaluation (Tables 2 and 3), which compared the degree of instability between the pre- and postoperative periods for each type of lesion separately, were also obtained in 114 patients. Regarding personal satisfaction, 92% of the patients reported having returned to activities similar to those in which they engaged before the injury with regard to sports, work and daily activities. DISCUSSION Injuries in the posterolateral corner of the knee are uncommon and often occur in association with other ligament injuries, particularly those to at least one of the cruciate ligaments (2,8,17). In our study, there were no isolated lesions of the posterolateral corner of the knee. The correct diagnosis of the structures involved in posterolateral injury is important because this type of lesion causes great instability, with disastrous consequences to the cartilage of the knee, if not diagnosed. These lesions also cause failure in primary ACL reconstructions (3,5,6,18). LaPrade et al. (14), in an anatomical study performed on cadavers, identified the main structures in the posterolateral corner of the knee as the fibular collateral ligament, the popliteus tendon and the popliteofibular ligament. We agree with these authors that these structures are the main CLINICS 2012;67(6):597-602 anatomical components of this region and that, therefore, any surgical technique should include their reconstruction. The importance of these structures in resisting excessive forces in varus and external rotation of the tibia was indeed demonstrated by several authors (19-21) in biomechanical studies in which resistance tests were performed with a section of each structure. However, these studies did not show how these structures should be reconstructed. The fibular collateral ligament is an important stabilizer in varus opening, and it functions in the secondary restraint of posterolateral tibial rotation at up to 30 degrees of knee flexion. However, at close to 70 degrees of flexion, this ligament becomes more vertical in the sagittal plane, which makes it difficult to resist the forces of external rotation. This resistance is the function of the popliteofibular ligament, as the tension in this ligament increases along with the flexion of the knee (22). The popliteofibular ligament is suggested to be the dominant structure when the knee is flexed and therefore should always be reconstructed (22). Biomechanical studies have determined the maximum amount of force that the fibular collateral ligament, popliteus tendon and popliteofibular ligament can with- stand. Maynard et al. (23) demonstrated that the popliteo- fibular ligament and the fibular collateral ligament cannot resist forces greater than 424 and 746 N, respectively. These authors proposed that the popliteofibular ligament could be reconstructed from the femur to the fibula. In their studies, LaPrade et al. (19) found the following cut-off forces for the failure of the ligaments and tendon: 295 N for the collateral ligament, 298 N for the popliteofibular ligament, and 700 N for the popliteus tendon. The differences are likely due to the limitations of studies with cadavers, in which there is a lack of homogeneity regarding gender, age and means of preservation. We used a 30-mm-wide section of the iliotibial tract, which is divided into two bands. One band is used as a graft to reconstruct the popliteus tendon (according to LaPrade et al. (19), this tendon fails when subjected to a 700-N force), and the other band is used to reconstruct the popliteofibular ligament (which fails when subjected to a 298-N force) (19). Each iliotibial tract band is 15 mm wide; according to Noyes et al. (4), an iliotibial tract width greater than 16 mm leads to failure when subjected to forces greater than 628 N. Precise isometric point positioning has already been determined to be essential in ACL reconstruction (24). Camanho (25) believes that the concept of isometry could improve the principles of reconstruction of the poster- olateral corner of the knee. There is isometry between the head of the fibula and the lateral epicondyle of the femur. The posterior aspect of the fibular head is isometric to the anterior aspect of the lateral epicondyle of the femur, and Table 2 - Varus stress. Varus stress Before surgery Total 6 to 10 mm .10 mm normal 3 to 5 mm 6 to 10 mm .10 mm After surgery 3 2.6 11 9.7 14 12.3 1 0.9 4 3.5 5 4.4 0 0.0 1 0.9 1 0.9 Total 32 28.0 82 72.0 114.0 100.0 n % n % n % 28 24.5 66 57.9 94 82.4 600