Applied Anatomic And Reconstruction Study On Knee Posterolateral Complex

Objective: The structure and characteristics of anatomical knee posterolateral complex descendants(PLC) were observed and measured to provide basis on anatomy and theory for clinical diagnosis and treatment of injuries in PLC, and explore the reconstruction and clinical efficacy on PLC injury.Method: Eight cases of human knee joints excluded knee injury, tumors, malformations and other diseases were selected in this study. The anatomy were carried out layer by layer, to observe and measure each structural posterolateral knee complex, its starting and ending points and the recognizable traveling to clarify anatomical relationships. In this study, 16 cases in total with injured knees were selected during May 2013 to November 2014 in our hospital for treatment of the injuries in knee posterolateral complex. The semitendinosus or(and) gracilis tendon allograft transplantation with equal length were applied to reconstruct the posterolateral complex. The varus stress in patients with tibial external rotation and internal controlled trials were carried on before and after surgery. All the Lysholm scores were calculated and analyzed by “t” test.Result:Posterolateral knee including three layers is divided into two parts of shallow iliotibial band and biceps(biceps femoris tendon, referred BFT). The intermediate layer generally is composed of the lateral patellar support band, patellofemoral ligaments and lateral gastrocnemius.The deep one contains the following components: ⅰ. posterolateral joint capsule, ⅱ. the lateral collateral ligament(LCL), ⅲ. popliteal tendon complex(PMTC), ⅳ. fabellofibular ligament(FFL), ⅴ. popliteofibular ligament(PFL), ⅵ. posterior cruciate ligament(PCL), ⅶ. plate stocks ligament. PLC is located in the posterior-lateral of the knee joint including knee lateral collateral ligament(LCL), popliteus tendon(PT), popliteofibular ligament(PFL), fabellofibular ligament(FFL), arcuate ligament(AL), posterolateral joint capsule and other structures near the syndesmosis joint.The proximal end of lateral collateral ligament originates from the outside of the lateral femoral condyle tuberosity, and goes along the rear of the iliotibial band downlink. Then, the distal part being synergy together with biceps, are attached to the outside of the distal fibular head and fibular styloid. The full-length of lateral collateral ligament is(50.84 ± 2.75) mm. The distance from the center of the lower edge to the lateral condyle of the articular cartilage is(17.64 ± 1.34) mm; the distance from the rear edge of the lateral femoral condyle is(21.06 ± 2.72) mm. The vertical distance from fibula fibular head attached to the tip of the pitch is(13.22 ± 2.27) mm.Popliteal muscle tendon originates from posteromedial of proximal end of tibia. It extends upward and gradually forms tendon, and goes cross lower part of lateral collateral ligament until ends at front edge of attachment point of lateral collateral ligament of femur. The distance from attachment point center to lower edge of lateral condyle is(12.26 ± 2.03) mm. The distance from attachment point center to rear edge of lateral condyle is(19.38 ± 1.66) mm, and the line of popliteal muscle tendon is(9.58 ± 1.23) mm beneath lateral tibial plateau.Popliteofibular ligament originates from the popliteal muscle belly and tendon junction, and goes outside to the bottom line. Then it ends on the fibular styloid side. The edge length is(9.92 ± 2.31) mm, and the rear edge length is(7.87 ± 1.53) mm.Fabellofibular ligament originates from fabella or lateral condyle, and ends at posterior lateral edge of fibulare belemnoid. The full length is(30.62 ± 2.53) mm. Sural beans are generally present in the inner lateral gastrocnemius, and uncertainty in its existing. In this experiment, the occurrence of sural beans is 37.5%(3/8).Based on the structural point, the arcuate ligament is usually presented as a "Y" shape, and mainly caused by the increasing in the thickness of the joint capsule. The medial arch length is(26.27 ± 1.42) mm; the lateral length is(27.34 ± 0.54) mm; the occurrence rate is 100%; the arcuate ligament goes downward along the lateral knee arterial constantly.The follow-up results on these 16 cases of knee posterolateral complex injury reconstruction patients are satisfactory. The duration of follow-up ranged between 10 to 24 months, with an average stage of 18 months. After surgery, all these 16 patients with wound recovered in good condition. No patient has recurrence of swellingin the knees, poor joint stability or abnormal gait, etc.. No patient had iatrogenic common peroneal nerve injury or deep vein thrombosis. No patient experienced varus instability in knee fully extended position. Knee flexion is 30°, except two patients’ rotation angles were small, one case with turn imbalance in level Ⅰ°. The angle of knee flexion was 110°to 130°, but there was one case having knee extension limitation of 10°. According to Lysholm knee score, the score in the patients accelerated from preoperative(50.75 ± 6.40) to postoperative(89.13 ± 3.16), with statistically significant difference(P < 0.05), and the effect of treatment were satisfied.Conclusion: The structure of PLC is complex. It is very important for the stability of knee joint. We have studied the morphological characteristics of PLC with clearer understandeing of its structure. On the other side, we know that this anatomical featrue is important for diagnosis and treatment of injuries in knees. PLC mainly has three layers. Biceps femoris tendon, lateral collateral ligament, popliteal muscle tendon complex and popliteofibular ligament are main components of PLC. These structures are interconnected to form a whole to maintain the stability of PLC. The stable triangle structure formed by lateral collateral ligament, popliteal muscle tendon and popliteofibular ligament is very important. It can effectively prevent genu varum, tibia external rotation and retrusion. Lateral femoral condylar and fibular head locate in the most superficial layer of the posterolateral complex, and the position are stable and can be the anatomical marks for ligament reconstruction positioning during the surgery. With autologous tendon or tendon allograft, reconstructing lateral collateral ligament and popliteofibular ligament in same length can effectively restore knee stability, and maximize the recovery function of knee.