Biomechanical And Clinical Study Of Posterolateral Corner Of Knee Joint

The knee joint is the biggest and most complicated joint in human body. It is also one of the main weight-bearing joint. Anatomically, it is categorized as trochoid joint, while it's actual movement involves complex movements such as rotation of tibia, femur sliding and rolling over tibial plateau. All these movement needs ligaments and tendons which surrounds the knee joint. In recent years, with the increase of traffic accidents and sports injuries, the incidents rates of knee joint ligaments injuries is increasing, especially the injury of posterolateral side of the knee. Recent studies find out that there is a complex structure in the posterolateral side of the knee called posterolateral corner, PLC. Or posterolateral complex, PLC. It is also called posterolateral structure, PLS. The injury of which may lead to knee joint extortion, varus and rear instability. If PLC injury is not effectively treated, the ligament reconstruction will not get satisfactory outcome. For these reasons, PLC injuries is receiving more and more attention. More attention has been focused on the anatomical and biomechanical study of PLC, however, since the complicated anatomy and relative little research data. Few agreement has been made. For these reasons, PLC injury is easy to be mis-diagnosed or mis-treated in clinical work. In China, less data in domestic research, in particular in biomechanical studies makes the domestic diagnosis and treatment of knee injuries entirely on foreign standards. In fact, Chinese people's body is smaller than Western people. Comparative anatomical studies also confirmed that the knee bone of Western people is larger than that of Chinese, Therefore, the diagnosis and treatment of PLC injury can not simply rely on foreign standards. Autopsy on the Chinese people PLC and the study of PLC biomechanics will provide data reference to clinical rehabilitation and reconstruction of ligament injuries. There are two definition of PLC, one is broad and the other is narrow. The broad one includes iliotibial tract, biceps femoris tendon, BFT. Lateral collateral ligament, LCL, Lateral patellar retinaculum, popliteal muscle tendon complex,PMTC, arcuate ligament,AL ,fabellofibular ligamaent,FFL, Lateral coronary ligament, lateral part of the joint capsule and tibiofibular ligament. PMTC includes popliteus tendon, PT, popliteofibular ligament,PFL, Tibial popliteal fascia, popliteal meniscal fascia; The narrow one includes BFT, LCL, PMTC, FFL, AL, etc. In ordinary clinical work, narrow definition is widely used. PLC's main function is to maintain the lateral knee joint static and dynamic stability, work against knee varus, tibial external rotation and limit tibia posterial movement. PLC injury is a severe knee injury, mostly induced of the sports injury, car accidents and fall injury. And often associated with other ligament posterior cruciate ligament injury. PLC injury can result in knee varus, tibial external rotation and knee flexion deformity. If not diagnosed and treated in time, will also lead to degeneration of articular cartilage and other ligament reconstruction surgery failure. Therefore, early diagnosis and treatment of PLC injury to the knee joint function is critical.There are 3 parts in this study: PLC biomechanical study; clinical effect of four tunnel reconstruction of posterior cruciate ligament reconstruction and operation treatment of acute PLC injury of the knee joint.1 Anatomical Observation and Biomechanics of External Rotational Torque of the Posterolateral Corner of the Knee: An in Vitro StudyObjective:The aim of this study was to observe anatomy and biomechanics of the posterolateral corner(PLC) of the knee in resisting external rotation. The results of this study may be applied to the design of guidance system for anatomic PLC reconstruction.Methods:A total of 8 fresh-frozen cadaveric knees were selected after exclusion of knees that displayed macroscopically degenerative changes or evidence of trauma. There were 5 male,3 female and 2 left ,6 right. The location, component, morphologic characteristics of the posterolateral corner (PLC) were observed by performing anatomical dissection. While successively sectioning the posterior curiae ligament (PCL), politieus tendon (PL) and lateral collateral ligament (LCL), biomechanical tests were performed consecutively by a biomechanical torsion test machine. The femur was fixed while the tibia fixture was attached to a free rotatable holder. The tibia external rotation degrees were measured at 0, 15, 30, 60 and 90 degree of knee flexion respectively after external rotation torques of 2Nm, 5Nm and 8Nm were given to the tibia of the intact and sectioned 8 cadaveric knees.Results:PLC, adjunct to superior tibiofibular synthesis, was located in the posterior lateral aspect of knee, which was mainly composed of LCL, PT, popliteofibular ligament (PFL), fabellofibular ligament, arcuate ligament, and posterolateral capsule. The external tibial rotation in intact knees was least at zero degree and greatest at 90 degree of flexion. The isolated sectioning of the PCL did not result in a significant increase in external rotation at 0, 15, 30, 60 and 90 degree of flexion(P>0.05). After that , Sectioning of PT showed a significant increase in external rotation at 0, 15, 30, 60 and 90 degree of flexion(P<0 .05), while the increase at 60 degree of flexion was the greatest. And then sectioning of LCL showed a significant further increase in external rotation at 0, 15, 30, 60 and 90 degree of flexion(P<0.05), and the increase at 30 degree of flexion was the greatest. There were the same tendency of outcomes applying rotational torques of 2Nm, 5Nm and 8Nm.Conclusion:The posterolateral region of the knee is an anatomically complex area that plays an important role in the stabilization of the knee relative to specific force vectors such as external rotation torque. The failure of the reconstruction of curiaet ligaments may be due to unrecognized or untreated posterolateral corner injuries. Isolated PCL sections produced no change in external rotation. Combined injury of PCL and PLC can produce more severe instability in external rotation. Only the combined PCL--PLC reconstruction can reset the knee to real physiological stability of external rotation, and thus can eliminate the excess force which placed on other ligaments. Politieus muscle,PT and PFL composite a whole functional unity, which is called polities muscle-tendon-ligament complex (PMTL). PMTL and LCL have the greatest important role in resisting external rotation, which coordinate well. While the LCL is the primary restraint at less than 30 degree of flexion, the contribution of the PMTL is greatest at more than 60 degree of knee flexion.2 Primary Clinical Results of Four-Bone-Tunnel Posterior Curiae Ligament Reconstruction With Tensioning of Remnant LigamentObjective:The purpose of this study was to investigate primary clinical results of the reconstruction of posterior cruciate ligament (PCL) under arthroscopy with four diagonally laid tunnels. Methods:From June 2006 to June 2008, 21 patients were treated with PLC reconstruction under arthroscopy with four diagonally laid tunnels. There were 15 males and 6 females, with the mean age of 28 years (ranged, 18 to 40 years). Two tibial tunnels were located at the diagonal angles: posteromedial bundle was on the inferomedial angle while the anterolateral bundle was on the superiolateral angle. The two femoral tunnels were located on the footprint, anterolateral bundle was on 10:30 (left) or 1:30 (right), while posteromedial bundle was on 8:30 (left) or 3:30 (right). Residual PCL fibers were saved during the operation. Injuries of the PLC were also treated in the same operation. Two bundles deep-freezed hippicus muscle tendon were folded in half and sutured together as allografts. Absorbable screws were used in grafts fixation.Results:Average follow-up was 14 months (12-18 months). Fifteen patients showed PDT (++) and six shows (+++) preoperation, 15 cases showed PDT (-), 5 cases shows (+), 1 case showed (++) postoperation. IKDC changed from 62.14±4.9 to 93.95±3.6. 17 cases were normal, 3 cases were near normal and 1 case were abnormal. Lysholm score significantly increased from 52.33±4.9 to 91.19±3.6.Conclusion:This four diagonal angle tunnel technique keeps more PCL fiber and better protects bone bridge between tunnels. Moreover, it is close to anatomic reconstruction. The clinical outcome proves to be satisfactory.3 Surgical Treatment of Acute Posterolateral Corner Injuries of the Knee Joint Objective:This prospective clinical study was performed to investigate the surgical treatment methods of the acute posterolateral corner injuries of knee joint and to observe the clinical outcomeMethods:From 2006.5 to 2008.10, twelve patients with 12 cases of acute PLC injury were treated. The mean age of patients was 31 years (range 23-47). Nine male and 3 female patients were included, with injuries of 5 rights and 7 left PLCs, 9 of the patients had combined PCL injuries, 3 had combined PLC and ACL injuries, 7 had combined LCL injuries, all patients had combined PMTC injuries. 8 had combined PFL injuries. The majority of patients in our study were involved in trauma, 10 patients had traffic accidents, 2 patients injured in strenuous exercises. First reconstruct the ACL and PCL using an allograft with arthroscope. Reconstruct the ACL with one bundle allograft while reconstruct the PCL with two-bundle allograft by two-bone tunnels. Then bend the knee to 70 degree, take posterolateral curved incision of 5-10cm, reveal the PLC injury site. Take local treatment of suture repair to those patients with PLC injuries at both ends with avulsion from attachment points. To those patients with fractures in PLC, suture repair the tendon and local anatomical reconstruction with allograft. Evaluate the knee joint function after operation according to IKDC standard and Lyshom score.Results:Mean follow-up in our series was 14 months (range, 12-18 months). Before operation, IKDC scores for the whole group included 0 patients with normal knees (A grade), 3 with near-normal knees(B grade), 7 with abnormal knees(C grade), and 2 with severely abnormal knees(D grade). At final follow-up, 3 knees were normal (A grade), 6 cases were near normal (B grade) , 2 cases were abnormal (C grade) and 1 cases were severely abnormal(D grade) according to IKDC standard. The preoperative Lysholm joint function score were 35-44, average 39 which contrast with 69-91, average 81 after surgery(P<0 .05).Conclusion:For acute PLC injuries, local suture repair to those injuries at both ends with avulsion from attachment points is a better choice. While the stability of the knee is better restored to those patients with PLC fractures if we take suture repair the tendon and local anatomical reconstruction with allograft...