Comparative analysis of the structural properties of the collateral ligaments of the human knee.
METHODS
Controlled laboratory study.


BACKGROUND
Varus knee instability arising from lateral collateral ligament (LCL) injury increases stress on cruciate ligament grafts, potentially leading to failure of reconstructed ligaments. In contrast to the medial collateral ligament (MCL), little is known about the structural properties of the LCL.


OBJECTIVE
To compare the tensile properties of the LCL and MCL complex of the human knee joint.


METHODS
Ten fresh-frozen cadaveric knees (mean ± SD age, 81 ± 11 years), free of gross musculoskeletal pathology, were obtained. Following dissection, the length, width, and thickness of the ligaments were measured using calipers, and bone-ligament-bone preparations were mounted in a uniaxial load frame. After preconditioning, specimens were extended to failure at a rate of 500 mm/min (approximately 20%/s). Force and crosshead displacement were used to calculate structural properties, including stiffness, yield strength, ultimate tensile strength, and failure energy.


RESULTS
The fan-shaped MCL was significantly longer (60%; P<.001), wider (680%; P<.001), and thinner (19%; P = .009) than the cord-like LCL. The LCL failed at either the fibular attachment (n = 6) or midsubstance (n = 4), while failure of the MCL primarily occurred at the femoral attachment (n = 7). Although the ultimate tensile strength of the MCL (mean ± SD, 799 ± 209 N) was twice that of the LCL (392 ± 104 N; P<.001), there was no significant difference in stiffness of the ligaments (MCL, 63 ± 14 N/mm; LCL, 59 ± 12 N/mm).


CONCLUSIONS
Despite differences in geometry and strength, there was no significant difference in stiffness of the MCL and LCL when tested in vitro.
Laboratory of Human Anatomy, University of Glasgow, UK.
William T
WT
Wilson
Angela H
AH
Deakin
Anthony P
AP
Payne
Frederic
F
Picard
Scott C
SC
Wearing
D000368:Aged; D000369:Aged, 80 and over; D001696:Biomechanical Phenomena / Q000502:physiology; D005260:Female; D006801:Humans; D007593:Joint Instability / Q000503:physiopathology; D007717:Knee / Q000502:physiology*; D008023:Ligaments, Articular / Q000033:anatomy & histology / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D009929:Organ Size; D013718:Tensile Strength / Q000502:physiology