Term
| the composition of ligament is similar to the composition of what other tissue? |
|
Definition
|
|
Term
| what are the 4 major components of ligament? |
|
Definition
| water, collagen, GAGs, elastin |
|
|
Term
| how much of the net weight of ligament is made up by water? |
|
Definition
|
|
Term
| what type of collagen is found in ligament? |
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Definition
|
|
Term
| how much of the net weight of ligament is made up by collagen (list wet and dry percentage) |
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Definition
| 25% of wet weight and 75% of dry weight |
|
|
Term
| how much of the total weight of ligament is made up by GAGs? |
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Definition
|
|
Term
| how much of the total weight of ligament is made up by elastin in most ligaments? |
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Definition
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Term
| how much of the total weight of ligamentum nuchae is made up by elastin? |
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Definition
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Term
| why does the ligamentum nuchae have so much elastin? |
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Definition
| ligamentum nuchae fibers go several hundred percent strain prior to failure to enable spinal flexion |
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|
Term
| the structure of ligament is similar to the structure of what other tissue? |
|
Definition
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|
Term
| describe unloaded ligament in one word |
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Definition
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Term
| how is the structure of ligament a bit different from the structure of tendon? |
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Definition
| ligament has less of a purely parallel arrangement of fibers compared to tendon |
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Term
| why is the arrangement of fibers in ligament not as parallel as the arrangement of fibers in tendon |
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Definition
| ligaments usually have to restrain motion in more than one pure direction |
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Term
| what do see, structure-wise, in the ligaments that control rotation? |
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Definition
| bands of spirally oriented collagen fibers that tighten with rotation |
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|
Term
| what are the functions of ligament? |
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Definition
| joint stability, force attenuation, protective reflexes, positional sense |
|
|
Term
| explain how ligaments provide joint stability |
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Definition
| ligaments protect joint structures such as articular cartilage, joint capsule, and meniscus from abrasive wear and tear |
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Term
| how do ligaments attenuate force? |
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Definition
|
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Term
| explain how ligaments provide protective reflexes |
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Definition
| overstretching a ligament produces a protective spinal cord reflex to contract the muscle and pull you back into safety |
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Term
| what happens to the protective reflex after a severe ankle sprain and how does this affect risk for future sprain |
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Definition
| If you've had a really bad ankle sprain and you've torn the receptor organs, they can't mechanically stimulate the protective reflex, so you are 5x more likely to have another ankle sprain |
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Term
| what is functional instability |
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Definition
| the instability present after an ankle sprain secondary to loss of protective relfexes in the ligaments |
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Term
| what part of joints enables them to have "position sense" |
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Definition
| sensory end organs in the capsule and ligament |
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Term
| what determines the frequency of signaling discharge of the sensory end organ? |
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Definition
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Term
| how do the sensory end organs react when you move the joint to stretch the capsule/ligament |
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Definition
| there is an increase in the frequency of discharge from the sensory end organs that goes up to the sensory cortex in the brain |
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Term
| why is the risk for recurrent sprains so high |
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Definition
| if you're jumping up and down and your sensory end organs have been disrupted, they don't signal up to the sensory cortex what position your foot is in, and you come down at a bad angle. When they're streched, the receptor rogans can't mechanically stimulate the protective reflex, so you just go down on it |
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Term
| is the change in frequency of sensory receptors as a function of joint angle linear or curvilinear? |
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Definition
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Term
| What are the 2 major determinants of functional joint stability? |
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Definition
| the body's structural limits of stability + neuromuscular control |
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Term
| what determines the body's structural outer limits of stability? |
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Definition
|
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Term
| is everyone's body's limits of stability the same? |
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Definition
| No, there is lots of variability of stability in terms of different geometry and different ligamentous/capsular stability |
|
|
Term
| describe how neuromuscular control can work for you and against you |
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Definition
| neuromuscular control can provide stability, but it can be the force that puts the joint over the edge: muscle forces in the wrong direction can cause problems, such as subluxation of the humeral head |
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|
Term
| what movement would give you a joint displacement curve for the ACL? |
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Definition
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|
Term
| how many mm does the tibia move anteriorly during physiological loading? |
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Definition
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Term
| about how much joint displacement occurs with a typical clinical test |
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Definition
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Term
| if you push/pull with 100N = 25 pounds of force on a stress test, what would happen |
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Definition
| nothing. You are not even mimicking the physiological loading that occurs across a large jiont |
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|
Term
| how many pounds of force are required on a stress test to get to the middle of the physiologic loading range |
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Definition
|
|
Term
| what produces the physiologic loading range |
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Definition
| the shearing and twisting forces of muscles |
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|
Term
| what is on the y axis of a load-joint displacement curve? |
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Definition
|
|
Term
| what is on the x axis of a load-joint displacement curve? |
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Definition
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|
Term
| how to have a good stress test? |
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Definition
| stabilize, use force to attempt to approach the physiological loading force of the person's own muscles |
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|
Term
| is the dependent variable on the x axis or the y axis |
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Definition
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|
Term
| is the independent variable on the x axis or the y axis |
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Definition
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|
Term
| when comparing joint laxity and forces of activity, which is the dependent variable |
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Definition
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|
Term
| when comparing joint laxity and forces of activity graphically, which is on the x axis |
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Definition
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|
Term
| what does a normal curve of joint laxity and forces of acitivity look like |
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Definition
| when you have greater activity, there is increaed joint laxity allowing one bone to move on another |
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Term
| when you have an injured curve, what does the curve look like |
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Definition
| the curve for injured tissue is higher than the curve for normal tissue, meaning there is more joint laxity for the same force of movement |
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Term
| what are you looking for when examining stress |
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Definition
| is there more laxity on the involved side compared to the uninvolved side |
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Term
| what will happen on a stress test if you don't push/pull vigorously enough |
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Definition
| you may see no difference it is only when you push strenuously that are likely to see laxity in testing that exists under normal muscle forces |
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|
Term
| what happens in stress testing when the primary restraint is torn but the secondary restraint is intact |
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Definition
| you might see slight laxity, but you might get a false negative |
|
|
Term
| what will happen to the tissues if the primary restraint is torn |
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Definition
| all of the stress is shifted to secondary restraitns which weren't really designed to deal with it. Over time, the secondary restraints become injured. |
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|
Term
| what does it take to see large laxity on a clinical test when the primary restraint is torn + secondary restraint is stretched or torn? |
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Definition
| patient must relax, technique must be good (strong force) |
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|
Term
| what is a joint arthrometer |
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Definition
| clinical testing with machine |
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|
Term
| what are two joint arthrometers for shearing tibia on femur |
|
Definition
| rolimeter air cast, KT2000 |
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|
Term
| should you test the involved or uninvolved side first and why |
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Definition
| test involved side first to surprise them and keep them from guarding. |
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|
Term
| what are 2 biomechanical properties to help with ligaments that are too short because of contracture? |
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Definition
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Term
| if you're low on the stress-strain curve, and you just impose a little stress for a short period of time and then release the stress, what will happen t o the material |
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Definition
| you are in the elastic range, so there will be no permanent deformation: the material will come right back to its original length or shape and you've done nothing |
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|
Term
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Definition
| if you take a low level load/stress within the elastic range and you impose it for a long period of time, it creates an increase in strain |
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|
Term
|
Definition
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|
Term
| what biomechanical property is used by the dynasplint pushing the elbow joint into extension with a constant moment |
|
Definition
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|
Term
|
Definition
| yes, but it depends on patient compliance |
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|
Term
| how does stress relaxation work |
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Definition
| push the joint until they feel increased stress to the point that they tell us to stop. Then hold them at that point and hold the strain constant. |
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|
Term
| what is held constant in stress relaxation? |
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Definition
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|
Term
| what changes in stress relaxation |
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Definition
| stress is high initially. Over time, the stress relaxes and we can move into a new point of discomfort |
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|
Term
| is serial casting an example of creep or of stress relaxation |
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Definition
|
|
Term
| what is held constant in creep? |
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Definition
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|
Term
|
Definition
|
|
Term
| what is the joint active system |
|
Definition
| similar to serial casting but used 30 minutes, 3 times a day |
|
|
Term
| how often does stress relaxation occur in serial casting? |
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Definition
|
|
Term
| what is a potential problem with the joint active system? |
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Definition
| straps are not wide, they would impose high contact pressure on the skin |
|
|
Term
| what is the effect of increasing strain rate on a ligament? |
|
Definition
| increase ultimate strength and energy at failure, make the ligament stiffer |
|
|
Term
| what part of the ligament is injured with higher strain rates? |
|
Definition
| mid-substance; the bone is stiffened, so the ligament is the weak link |
|
|
Term
| what part of ligament-bone interface is more likely to be injured with slower strain rates? |
|
Definition
| bone, avulsion fracture. Because bone and soft tissue are both weaker and less stiff, but moreso with bone |
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|
Term
| what are the effects of immobilizaiton |
|
Definition
| better bone healing, but for other tissues: decreases ultimate strength and stiffness, increased strain at failure, causes adhesions, can cause contrature of ligament if immobilized in a shortened position |
|
|
Term
| what are the results of contracture of the ligament? |
|
Definition
| loss of functional ROM = alteration of normal movement patterns that places other tissues at risk for injury |
|
|
Term
| if you have an MCL injury, is it better to leave it alone or to repair + immobilize? |
|
Definition
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|
Term
| what are the effects of immobilization on the dogs, considering laxity? |
|
Definition
| during immobilization, there is atrophy. When the immobilzer suddenly comes off, the poweruful muscle-tendon forces put tremendous stress on weakened tissues, making the joints lax. |
|
|
Term
| how is strength affected by immobilization? |
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Definition
| normal strength returns faster in non-immobilized. |
|
|
Term
| what should you do if you ever strain your MCL? |
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Definition
| don't get it repaired. Get a hinge brace so that you can move your knee but still be protected from valgus stress and IR. |
|
|
Term
| what are the ligament/capsule requirements for optimum healing? |
|
Definition
| good blood supply, controlled mobilization, protection from injurious stresses |
|
|
Term
| describe why controlled mobilization is needed in healing ligament |
|
Definition
| the tissue needs some loading to get an optimally healed result |
|
|
Term
| describe how to protect a healing ligament from injurious stresses |
|
Definition
| be sure that other ligaments are intact, provide external support such as a hinge brace, modify activities, redirect from dangerous activities like football |
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|
Term
| how to protect ligaments from chronic irritation related to skeletal malalignment? |
|
Definition
| when someone has an acute injury to a ligament, look at alignment to be sure there are not malalignments that apply additional stress. For example, if someone has acute injury to MCL but also has forefoot varus, that will cause excessive prontation, which will cause dynamic genu valgus, which will increase MCL irritation at the knee. It will be difficult for this MCL to heal. it could become chronically injured and never heal. It needs some protection. |
|
|
Term
| what is one example of chronic irritation of a ligament related to dynamic overloading |
|
Definition
| repetitive overhead throwing |
|
|
Term
| why does repetitive overhead throwing cause MCL irritation at the elbow |
|
Definition
| it applies repetitive high magnitude valgus stress. ΣM=Iα. The sum of the moments is equal to the moment of inertia of the ball/lower arm times the angular velocity. The high velocity and the angle put a lot of stress through the MCL |
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|
Term
| Explain ΣM=Iα at the elbow for repetitive overhead throwers |
|
Definition
| you get valgus overload at the elbow secondary to high magnitude angular accelration and moment of inertia. |
|
|
Term
| What creates the valgus moment? |
|
Definition
| the mass from what the thrower is holding |
|
|
Term
| how does valgus affect contact area and force in the elbow? |
|
Definition
| valgus stress drives the radial head and capitulum together with decreasd contact area and increased force. Puts a lot of tensile stress on the MCL and compressive stress on radius-capitulum |
|
|
Term
| what formula explains the tremendous valgus loading in overhead throwers |
|
Definition
| ΣM=Iα. Intertia is large and so is the angular acceleration. The resisting moment is huge. |
|
|
Term
| how do some pitchers get evengreater valgus stress at the elbow with the pick off attempt? |
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Definition
| with the pick off attempt, the pitcher doesn't want to show early movement with his body. He uses his upper extremity to generate ball velocity. The moment ofinertia of the forearm, hand, and ball must be overcome during the acceleration phase of the throw. Acceleration with internal rotation pulls tensile stress through the ulnar collateral ligament to bring the forearm, hand, and ball along. the radial head feels increased compressive stress against the capitulum as the elbow moves into valgus |
|
|
Term
| what are some ways to decrease valgus loading of the throwing elbow? |
|
Definition
| more flexed elbow at ball release, plant foot first and then rotate trunk, pitch overhand |
|
|
Term
| how does a more flexed elbow at ball release reduce valgus loading of the trhowing elbow? |
|
Definition
| with a more extended elbow, the forearm and hand have a greater oment of inertia about the rotating trunk, creating more resistance to acceleration and causing it to lag behind more |
|
|
Term
| how does planting front foot prior to rotating as opposed to trunk rotation followed by planting the front foot release reduce valgus loading of the trhowing elbow? |
|
Definition
| trunk rotation can be fueled by having both feet on the ground. |
|
|
Term
| how does overhand pitching as opposed to side arm pitching reduce valgus loading of the trhowing elbow? |
|
Definition
| side arm pitching requires more ball velocity from UE motion and increases valugs stress imposed on the elbow |
|
|
Term
| describe the moving valgus stress test |
|
Definition
| start in flexion with some valgus. Extend elbow quickly as stressor is maintained. |
|
|
Term
| what is positive on the moving valgus stress test |
|
Definition
| pain reproduced 120-70 deg |
|
|
Term
| what to do if a patient reports instability with activity that you can't demonstrate on clinical exam |
|
Definition
| believe the patient! The patient is experiencing the influence of powerful joint forces. |
|
|
Term
| what is at risk for injury when ligaments are unstable |
|
Definition
| other ligaments, capsules, meniscus, articular cartilage |
|
|
Term
| what can you change to prevent more injury? |
|
Definition
| surgical repair, external support, activity modification, activity redirection. |
|
|
Term
| how to treat ligamentous contractures? |
|
Definition
|
|
Term
|
Definition
| if folks are not doing high magnitude, forceful activities then braces are protective. They can be false protection for very vigorous and forceful activities. |
|
|
Term
| what modalities are good for ligaments |
|
Definition
| ultrasound, low level laser |
|
|
Term
| describe ultrasound for ligament |
|
Definition
| ultrasound early after surgical injury increases the ultimate strength and energy at failure. Pulsed, non-thermal. |
|
|
Term
| describe low laser level for ligamnts |
|
Definition
| low level laser shows increase in ultimate strength and stiffness after surgery. |
|
|
Term
| how do ultrasound and low level laser help ligaments? |
|
Definition
| mechanical stimulus making the reparative cells be more active. |
|
|
Term
| if someone has to have immobilization for some reason, what do you do? |
|
Definition
| be careful bringing them back. Don't stretch them because they are too weak to resist the stress initially. |
|
|
Term
| summarize the goal of interventions for ligament/capsular injuries |
|
Definition
| facilitate good blood supply, protect from too much stress, gentle mobility to optimize timely return of ligament mechanical properties, look for skeletal alignment and movement patterns that migh impose unwanted stress on healing tissues |
|
|
Term
| when is capsular shrinkage indicated? |
|
Definition
| in cases where capsular and ligamentous tissues are all stretched out, causing instability, and you want to shorten them. |
|
|
Term
| what is the most common locatin of capsular shrinkage |
|
Definition
|
|
Term
| how does capsular shrinkage work? |
|
Definition
| laswer energy increases temperature, shrinks the collagen. Denatures the collagen |
|
|
Term
| what happens to shrinked tissue? |
|
Definition
|
|
Term
| what happens to tissue near the shrunken capsule? |
|
Definition
| can also be injured, which is bad |
|
|
Term
| what are the post-surgical protocols for capsular shrinkage |
|
Definition
| 4 weeks of immobilization in sling and swath. No abduction and ER too early. |
|
|
Term
| is thermal shrinkage good? |
|
Definition
| good short term results, but not always good long term results. Low levels of physiologic loading can cause creep of the shrunken tissue. |
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