JOINT STABILIZATION

1. Passive: Restraint imposed by ligament and joint capsule.

Affected by:

a. length of ligament

b. ligament stiffness quality

2. Dynamic: Restraint imposed by muscle activation

Affected by:

a. Muscle force opposing ligament deformation

b. Coactivation of antagonists

COORDINATION OF PASSIVE/ACTIVE STABILIZATION

1. Preset muscle contraction

2. Feedback from ligament mechanoreceptors

a. Proprioception: Response to muscle/ligamtent sensory end organs

GRADES OF LIGAMENT SPRAINS

Grade I	Mild, no increased joint laxity
Grade II	Moderate, slight but not severe joint laxity
Grade III	Severe, complete disruption with significant joint laxity

MECHANISMS OF LIGAMENT STRESS

Tensile Loads produced by:

a. Contact mechanisms

b. Non-cantact mechanisms

LIGAMENT HEALING OPTIMAL CONDITIONS

1. Continuity of torn fibers--vascularity
2. Controlled functional stresses stimulate & direct healing response
3. Protection for harmful stresses during collagen synthesis phase

HIGH/LOW RISK FACTORS WHICH INFLUENCE TREATMENT PROTOCOL

1. Age
2. Activity level
3. Associated lesions
4. Degree of laxity (I, II, or III)

DATA ON OUTCOMES: SURGERY VS. NON-SURGERY PER KNEE LIGAMENTS

Criteris:	Subjective, functional, objective
Outcome:	Excellent, good, fair, unsatisfactory
NOTE:	Non-surgery does not mean no treatment
For:	Grades I and II--MCL, LCL, ACL, PCL
Results:	90% good to excellent--non-surgery
For:	Grade III--MCL with intact ACL
Results:	90% good to excellent--non-surgery
For:	Isolated ACL (III) High-risk
Results:	60-85% unsatisfactory--non-surgery
	85-90% good to excellent--surgery
For:	Isolated ACL (III) Low-risk
Results:	85-90% good to excellent--non-surgery
For:	MCL/ACL (III) combo., High & Low-risk
General Consensus:	MCL repair and/or augmentation
	ACL primary substitution