TY - THES ID - 135919445 TI - The anterolateral ligament of the knee : anatomy, biomechanics, radiology and clinical implications. AU - Claes, Steven AU - Bellemans, Johan AU - KU Leuven. Faculty of medicine. Department of development and regeneration. PY - 2013 SN - 9789082126808 PB - Leuven KU Leuven DB - UniCat UR - https://www.unicat.be/uniCat?func=search&query=sysid:135919445 AB - While Paul Segond in 1879 already briefly mentioned the existence of a pearly, fibrous band at the anterolateral aspect of the human knee, current anatomic textbooks do not contain the notion of a ligamentous structure connecting the femur with the anterolateral tibia. The persistence of rotational instability reflected in the pivot-shift test still remains a major issue after contemporary reconstruction of the anterior cruciate ligament (ACL). Therefore, the goal of this doctoral thesis was to confirm the existence and to characterize the anatomy of Segonds pearly, fibrous band (further termed anterolateral ligament (ALL)), investigate its biomechanical function with regard to tibial rotation and to demonstrate the relevance of these findings for current clinical practice. Methods:(1) The effect of ACL reconstruction on tibial rotation was studied in a 3-D in vivo kinematic analysis in patients performing various motor tasks including pivoting. (2) The ALL was investigated in 41 human cadaveric knees; the dimensions of the ALL and relation with anatomical landmarks were measured and recorded. (3) Navigated knee kinematics were obtained from 10 fresh-frozen cadavers in the native knee, after sequential cutting of the two bundles of the ACL and the ALL in different orders. (4) Segond fracture characteristics were studied on MRI images of 26 subjects and compared with the anatomical findings on the tibial ALL insertion. (5) The presence and injury pattern of the ALL was studied on MRI images of 271 ACL-injured subjects. Results: (1) Both single- and double-bundle ACL reconstruction did not affect tibial rotation witnessed in the ACL-deficient knee. (2) The ALL was found in 97% of the dissected knees as a distinct ligamentous structure at the anterolateral aspect of the human knee, invariably originating on the lateral femoral epicondyle and inserting on the anterolateral tibia. (3) Selective sectioning of the ALL caused a significant increase in internal tibial rotation, and this in both the ACL-deficient as well as in the intact knee, while the ACL showed negligible restraint to tibial rotation. Sectioning of the ALL proved to be vital for the occurrence of an IKDC grade III pivot-shift in the ACL-deficient knee. (4) The Segond fracture was delineated as a bony avulsion of the ALL. (5) The ALL demonstrated a high incidence (78%) of MRI abnormalities in ACL-injured patients.Discussion:Previously undescribed, the ALL was identified as a distinct anatomical structure of the human knee, exerting a restraining effect on internal tibial rotation and the pivot-shift. Contrary to general belief, the restraining effect of both the native and reconstructed human ACL on tibial rotation was demonstrated to be negligible. Although the concept of anterolateral rotatory knee instability developed by Jack Hughston in the 1970s, already implied a combination of injuries to both the ACL and the anterolateral stabilizing structures, this interesting notion has become obsolete under the boom of arthroscopic knee surgery. However, the high incidence of ALL lesions witnessed on MR images of ACL-injured subjects and its causative relationship with the occurrence of a high-grade pivot-shift, yield new insights for the diagnosis and treatment of common knee instability patterns, previously attributed to isolated injuries of the ACL or one of its bundles. ER -