Medial knee injury: Part 1, static function of the individual components of the main medial knee structures.
BACKGROUND
There is a lack of knowledge on the primary and secondary static stabilizing functions of the posterior oblique ligament (POL), the proximal and distal divisions of the superficial medial collateral ligament (sMCL), and the meniscofemoral and meniscotibial portions of the deep medial collateral ligament (MCL).


OBJECTIVE
Identification of the primary and secondary stabilizing functions of the individual components of the main medial knee structures will provide increased knowledge of the medial knee ligamentous stability.


METHODS
Descriptive laboratory study.


METHODS
Twenty-four cadaveric knees were equally divided into 3 groups with unique sequential sectioning sequences of the POL, sMCL (proximal and distal divisions), and deep MCL (meniscofemoral and meniscotibial portions). A 6 degree of freedom electromagnetic tracking system monitored motion after application of valgus loads (10 N.m) and internal and external rotation torques (5 N.m) at 0 degrees , 20 degrees , 30 degrees , 60 degrees , and 90 degrees of knee flexion.


RESULTS
The primary valgus stabilizer was the proximal division of the sMCL. The primary external rotation stabilizer was the distal division of the sMCL at 30 degrees of knee flexion. The primary internal rotation stabilizers were the POL and the distal division of the sMCL at all tested knee flexion angles, the meniscofemoral portion of the deep MCL at 20 degrees , 60 degrees , and 90 degrees of knee flexion, and the meniscotibial portion of the deep MCL at 0 degrees and 30 degrees of knee flexion.


CONCLUSIONS
An intricate relationship exists among the main medial knee structures and their individual components for static function to applied loads.


CONCLUSIONS
Interpretation of clinical knee motion testing following medial knee injuries will improve with the information in this study. Significant increases in external rotation at 30 degrees of knee flexion were found with all medial knee structures sectioned, which indicates that a positive dial test may be found not only for posterolateral knee injuries but also for medial knee injuries.
Griffith
Chad J
CJ
Division of Sports Medicine, Department of Orthopaedic Surgery, University of Minnesota, Minneapolis, Minnesota 55454, USA.
LaPrade
Robert F
RF
Johansen
Steinar
S
Armitage
Bryan
B
Wijdicks
Coen
C
Engebretsen
Lars
L
D000368:Aged; D000369:Aged, 80 and over; D001696:Biomechanical Phenomena; D006801:Humans; D007593:Joint Instability / Q000503:physiopathology; D007718:Knee Injuries / Q000503:physiopathology*; D007719:Knee Joint / Q000033:anatomy & histology*; D008875:Middle Aged; D016059:Range of Motion, Articular / Q000502:physiology; D000070600:Tibial Meniscus Injuries