Anatomical Study Of The Lateral Soft Tissue Of The Patella

Objective: Lateral retinacular release(LRR) is a surgical procedure which is common performed to treat patellofemoral instability. The anatomy of the lateral retinaculum is incompletely understood at present. However, an inappropriate LRR would lead to medial subluxation of the patella. The discovery of the anatomy structural properties of the lateral retinacular and each function of its components will provide information needed for rational lateral release procedures. The aim of the present study was to elucidate the anatomical structures of the lateral soft tissue restraints of the patella, which was morphologically important for the further biomechanical studies.Method: Totally 10 fresh-frozen cadaveric knee specimens with normal bony structure were included in the present study. The femur and tibia were transected at both 20 cm above and below the knee. The deep fascia could be identified after removing the skin and subcutaneous tissue. It was attached to the iliotibial band(ITB) posteriorly, and passed over the patella anteriorly without attaching to it. Remove the deep fascia beginning anteriorly where it was easily defined. Then, the superficial tissue layers of the lateral retinacular could be identified form the anterolateral side of the knee. They consisted of the superficial fibers of ITB and the longitudinal fibers extended from the tendon of the vastus lateralis. Blunt dissect and reflect laterally the superficial tissue layers from their attachments to the quadriceps tendon. The deep transverse fibers, which had been termed the iliotibial band-patella(ITB-P) fibers, connected to the lateral border of the patella and ITB. The lateral patellomeniscal ligament(LPML) and lateral patellotibial ligament(LPTL) were below the ITB-P fibers. Dissect and search the lateral patellofemoral ligament(LPFL) from the upper side of the deep transverse fibers. Observation was taken of the morphology, attachments, position and orientation of these structures. Record their occurrence rates. Measurements were taken of their length, thickness, the width of origination and termination using a vernier caliper. The SPSS13.0 statistical software was used for statistical assessment.Results: The lateral retinacular of the knee was divided into superficial, intermediate and deep layers. The components consisted of derivatives of fascia, the quadriceps and the capsule. The most superficial layer was deep fascia. The quadriceps aponeurosis, ITB and its extensions were in the intermediate layer. The joint capsule and the ligaments which were thickened bands of the lateral joint capsule were in the deep layer. The deep fascia was the first layer below the skin and subcutaneous tissue. It passed over the patella, but not attached to it and could been separated from it easily. Partial fibers of the deep fascia were attached to the quadriceps aponeurosis proximally. Distally this attachment, the deep fascia thickened to form the ITB. The fibers on the superficial layer of the ITB proceeded obliquely, crossed over and firmly adhered to the quadriceps aponeurosis and anterior fibers of the ITB. They extended anteriorly to the distal patella and the patellar tendon, where they fused with the quadriceps aponeurosis. These fibers were functionally called the superficial oblique retinaculum. The deep transverse fibers of the ITB formed the ITB-P fibers, which connected to the patella and vastus lateralis obliquus. But they were not attached to the lateral epicondyle of the femur. And they were not a distinct separate layer. These fibers were dense, strong and could been consistently found in all knees. The occurrence rate was 100%. The joint capsule was thickened to form the LPFL. It was variable from knee to knee. Its margins were difficult to define clearly. The attachments of the LPFL were the widest part of the lateral patella and the lateral femoral epicondyle. Its occurrence rate was 40%. Similarly, LPML was formed by a condensation of capsule. It was connected the anterolateral part of the lateral meniscus to the inferolateral part of the patella. The fibers of quadriceps aponeurosis descended distally along the lateral border of the patella and the patellar tendon to form the LPTL. It was attached to the lateral tibial condyle between the Gerdy’s tubercle and tibial tuberosity. It also fused anteriorly with the deep part of the joint capsule. The fibers of the LPML and LPTL were loose and vary considerably. Their occurrence rates were 90%.Conclusions: 1The lateral retinacular of the knee is divided into three layers, include the deep fascia in the superficial layer, the quadriceps aponeurosis, ITB and its extensions in the intermediate layer, the joint capsule and the ligaments which thickened by lateral joint capsule in the deepest layer. 2The ITB-P fibers of the lateral retinaculum are the widest and thickest. They are dense and transverse orientation. 3The ITB combined with its ITB-P fibers are served as dynamostatic structure, which restrain the medial soft tissue from pulling the patella to translate and tilt medially. 4The deep fascia connects to the quadriceps tendon proximal and lateral to the patella by the lateral extension of the quadriceps aponeurosis. This connection provides an additional retinacular action by pulling the tendon laterally and posteriorly.