L03. Ligament Structure, Injuries, and Repair Flashcards
What are the 2 basic functions of ligaments?
- Hold the joint together
- Define the range of motion of the joint
What do ligaments consist of?
Bundles of collagen fibers that have high strength in tension but buckle during compression
List the structure of a ligament from the largest to smallest component
Ligament –> Fascicle –> Fiber –> Fibril –> Subfibril –> Microfibril
What are the 4 regions related to the deformation of a ligament?
- Toe Region (crimp straightened, low forces)
- Linear Region (collagen fibers stretch elastically, proportional resistance)
- Microdamage (Begin to lose some mechanical properties)
- Macrodamage (tear)
What is a sprain?
Stretch or partial tear of ligaments due to lengthening beyond normal excursion
What joints are most vulnerable to being sprained?
Ankle, knee, and wrist
What are the levels of severity for a sprain?
Grade I (Microdamage)
Grade II (Partial tear)
Grade III (Complete tear)
How do you treat a sprain? Explain for each grade of sprain
Grade I and II: Conservative (reduce activity, ice, physical therapy)
Grade III: Surgical repair
What are the 3 articulations that allow for knee movement?
Lateral and medial femoral condyles
Patellofemoral
Purpose of ligaments in the knee
- Help guide motions of the knee
- Provide stability
- Restrict several of the possible 6 degrees of freedom between the femur and tibia
Is the knee considered vulnerable?
Yes
What is the function of the anterior cruciate ligament (ACL)?
Resists anterior translation of the tibia
What is the function of the posterior cruciate ligament (PCL)?
Resists posterior translation of the tibia
What is the function of the medial collateral ligament?
Resists valgus deformation of the knee
What is the function of the lateral collateral ligament?
Resists varus deformation of the knee
Knee “valgus” test vs. Knee “varus” test
Valgus: knees bowed inwards (knock knees)
Varus: knees turned outward (bowlegs)
How does someone usually injure there ACL
Associated with a decelerating twisting motion
How are ACL tears usually treated?
Partial tears: non-surgically with a brace and natural healing
Full tear: Surgery
How is the PCL most commonly damaged?
By a blow to the front of the tibia (dashboard injury or fall onto the tibia)
What are the main bones and components of the shoulder?
The glenoid cavity and scapula
What is the main action that the rotator cuff muscles do?
Pull the humeral head into the glenoid
How many rotator cuff muscles do you have?
2 in front and 2 in the back (4 total)
- 2 on the upper part of the humerus and 2 on the lower
What is bursitis?
condition where the fluid-filled sac that cushion joints becomes inflamed and painful. This can lead to impingement syndrome
What are some shoulder injuries/syndromes people can experience?
Arthritis, bursitis, impingement, rotator cuff tear, and dislocation
What is impingement syndrome?
rotator cuff is pinched between the head of the humerus and the acromion process of the scapula
What are the 2 types of rotator cuff tears?
- Partial: conservative treatment
- Complete: surgical treatment needed
What is glenohumeral instability?
Articular surfaces of humerus and glenoid not appropriately aligned
What happens with a glenohumeral dislocation?
Humerus slips out of glenoid completely
What is a glenohumeral subluxation?
Only partial dissociation of humeral head and glenoid
