See: -
Biomechanics of ACL:
- Effects of Immobilization:
- immobilization significantly decreases strength and energy-absorbing capacity of rabbit bone-ligament-bone preparations;
- effect is most obvious at the ligament-bone junction;
- under conditions of stress deprivation, there is increased
osteoclastic activity at the junctional region of bone;
- period of immobilization leads to increased likelihood that failure in response to
strain would occur at this junction;
- stress deprivation decreases strength in both the ligament and in the junction, and functional failure becomes more likely with increased immobilization;
- effects of immobilization are reversible;
- after immobilization junction regains its strength, although relatively slowly;
- four to 12 months of recovery may be needed before junction recovers its normal biomechanical characteristics;
- Ligament Repair:
-
collagen synthesis and degradation proceed simultaneously, as in other types of wound healing, but collagen content increases;
- initial collagen is
type III, although later composition changes to predominantly
type I collagen;
-
glycosaminoglycans also increase in the early phase of wound healing;
- w/ remodeling & maturation, contents gradually return toward normal;
- injured ligaments sometimes demonstrate the ability to contract or to "tighten up."
- rat medial collateral ligaments Z-lengthened are able to contract to normal tightness in three weeks;
- there is an assoc increase in the amount of actin as measured by immunofluorescent staining;
- actin is same contractile protein found in thin filaments of muscle sarcomeres and in the cytoplasm of mobile cells;
Attachment of autogenous tendon graft to cortical bone is better than to cancellous bone: a mechanical and histological study of MCL reconstruction in rabbits.
