The Journal of Bone and Joint Surgery, Vol 72, Issue 3 382-392, Copyright © 1990 by Journal of Bone and Joint Surgery, Inc
The effects of transection of the anterior cruciate ligament on healing of the medial collateral ligament. A biomechanical study of the knee in dogs
SL Woo, EP Young, KJ Ohland, JP Marcin, S Horibe and HC Lin
Orthopaedic Bioengineering Laboratory, San Diego Veterans Administration Medical Center, California.
The effect of concurrent injury to the anterior cruciate ligament on the
healing of injuries of the medial collateral ligament was studied in dogs.
In Group I, isolated transection of the medial collateral ligament was
performed; in Group II, transection of the medial collateral ligament with
partial transection of the anterior cruciate ligament; and in Group III,
complete transection of both the medial collateral ligament and the
anterior cruciate ligament. The three groups of animals were examined six
and twelve weeks postoperatively with respect to varus-valgus rotation of
the knee and tensile properties of the femur-medial collateral
ligament-tibia complex. The varus-valgus rotation of the knee was found to
be the largest in Group-III specimens at all time-periods and was 3.5 times
greater than the control values at twelve weeks. Group-I and Group-II
specimens also showed large varus-valgus rotations at time zero, but the
rotations returned to the control values by twelve weeks. For the
structural properties of the femur-medial collateral ligament-tibia
complex, the values for ultimate load for Groups I and II reached the
control values by twelve weeks, while that for Group III remained at only
80 per cent of the control value. Both energy absorbed at failure and
linear stiffness for all three groups were less than those for the controls
at six weeks, and only linear stiffness returned to the control values by
twelve weeks. For the mechanical (material) properties of the healed
ligament substance, the values for modulus and tensile strength were
markedly lower than the control values for all groups at six weeks. By
twelve weeks, the tensile strength of Group-I specimens had increased to 52
per cent of the control value, while those of Groups II and III were only
45 and 14 per cent, respectively. Our results demonstrate that healing of
the transected medial collateral ligament is adversely affected by
concomitant transection of the anterior cruciate ligament. Both
varus-valgus rotation and mechanical properties of the healed ligament
failed to recover in knees that had combined transection of the anterior
cruciate and medial collateral ligaments. The structural properties of the
femur-medial collateral ligament-tibia complex in tension recovered more
rapidly as a consequence of the large mass of reparative tissue that formed
in the medial collateral ligament of the anterior cruciate-deficient knees.