Term
| how big is the transition of ligament/tendon/capsular tissue into bone? |
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Definition
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Term
| describe the stress concentration at insertion sites |
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Definition
| stress concentration occurs becase the bone is stronger/stiffer than the soft tissue |
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Term
| what helps to reduce stress concentration at insertion sites? |
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Definition
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Term
| what are the 2 major types of insertions |
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Definition
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Term
| which type of insertion site is deeper? |
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Definition
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Term
| describe direct insertion structure |
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Definition
| has 5 zones of deep fiber groups |
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Term
| describe direct insertion zone I |
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Definition
| tendon/ligament proper, some capillaries and fibroblasts - more cartilage |
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Term
| describe direct insertion zone II |
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Definition
| fibrocartilage, flat fibroblasts and oval chondrocytes with a little more fibrocartilage overall |
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Term
| describe the structure of direct insertion zone III |
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Definition
| mineralized fibrocartilage with tidemark line between zones II and III - mineralized fibrocartilage |
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Term
| describe the structure of direct insertion zone IV |
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Definition
| bone with inserting collagen fibers blending into bone |
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Term
| what is the main component of zone 1 |
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Definition
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Term
| what is the main component of zone 2 |
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Definition
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Term
| what is the main component of zone 3 |
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Definition
| mineralized fibrocartilage. |
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Term
| what is the main component of zone IV |
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Definition
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Term
| what are the 2 transitional zones of direct insertions |
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Definition
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Term
| in what zones are we unlikely to see failure? |
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Definition
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Term
| why are ruptures rare in zones 2, 3? |
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Definition
| because the transition is so smooth and amazing |
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Term
| describe indirect insertions |
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Definition
| Superficial collagen fibers blend with the periosteum while some deep fibers go intobone without transitional fibrocartilage zones. |
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Term
| how does the deep osteogenic layer of indirect insertions attach to the bone? |
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Definition
| the deep osteogenic layer attaches to the subperiosteal bone via Sharpey's fibers. |
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Term
| describe Sharpey's fibers |
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Definition
| collagen fibers that originate in periosteum and perforate into subperiosteal bone. They are like nails that come up to anchor the inserting fibers from the soft tissue into the bone |
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Term
| are there any superficial fibers in direct insertion sites? |
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Definition
| yes, there are a few superifical fibers that blend with the periosteum, but most are deep fibers that pass through the 4 zones |
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Term
| what types of attachments tend to have direct insertions? |
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Definition
| proximal attachments of collateral ligaments tend to be direct |
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Term
| what types of attachments tend to have indirect insertions? |
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Definition
| distal attachments of ligaments |
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Term
| are tendon insertions direct or indirect? |
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Definition
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Term
| are the direct insertion's transitional zones vascular or avascular |
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Definition
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Term
| what is the function of ligament/tendon/capsule insertions into bone? |
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Definition
| transmit force from soft tissue to stiff bone without injury from stress concentration |
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Term
| what is the singlemost powerful soft tissue force in the body? |
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Definition
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Term
| which component of the patellar tendon force puts tensile stress on the ACL? |
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Definition
| anteriorly directed component |
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Term
| how does the ACL elevation angle change as you go through knee flexion to extension? |
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Definition
| when the knee goes into extension, the ACL elevation angle increases to become more vertical |
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Term
| what is the orientation of the trabeculae in the tibial plateau? |
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Definition
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Term
| if you have failure of the ACL in knee flexion, what fails and why? |
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Definition
| the bone fails because the ACL is emitting tensile stress along a line that is not parallel to the trabeculae. |
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Term
| if you have failure of the ACL in knee extension what fails and why? |
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Definition
| ACL; the ACL is pulling more along the line of the collagen fibers in the trabeculae of the bone so the bone is stronger. Also, the line of the pull of the patellar tendon compared to the tibia is greatest when the knee is in extension because they are closest to parallel in this position (the angle is smallest.) Therefore, if there is a lot of force in the patellar tendon, the anteriorly directed component of the patellar tendon is also strong. But in extension, the ACL is vertically oriented and not in a good position to resist the anteriorly directed patellar tendon force. It takes a lot of force from the ACL to match the anteriorly direced component of the patellar tendon force, the ACL will fail. |
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Term
| is the ACL more likely to fail when the quads are contracted and why? |
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Definition
| yes; the quads produce a greater anteriorly directed force of the patellar tendon, which the ACL is not good at resisting |
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Term
| why are girls more at risk for ACL rupture than boys? |
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Definition
| girls land with more extended knees compared to boys. Also, girls patellas are more anterior, increasing the anteriorly directed force of the patellar tendon |
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Term
| how does a faster strain rate affect the location of failure? |
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Definition
| faster strain rates tend to cause mid-substance failures |
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Term
| what area is most likely to fail in general? |
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Definition
| mid-substance failure is more common than avulsion fracture because the bone is generally stronger than the soft tissue |
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Term
| why is it uncommon to see insertion site failures in zones 2 and 3? |
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Definition
| they are effective transition zones in minimizing stress concentration |
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Term
| what are the effects of immobilization on insertion sites? |
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Definition
| decrease in ultimate strength, stiffness, and energy at failure |
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Term
| is bone or ligament more likely to fail after immobilization? |
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Definition
| increased incidence of avulsion ffracture, particularly for indirect insertions because of subperiosteal bone resorption. The bone is the more metabolically reactive tissue. The atrophy will be more pronounced in the bone than in the soft tissue, so the bone is the weak link. |
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Term
| describe remobilization of insertion sites after immobilization |
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Definition
| the return of mechanical properties with remobilization can be very, very, very slow and recovery may never happen |
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Term
| how to introduce movement after immobilization? |
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Definition
| remember that the tissue is weak. Gradually reintroduce to exercise |
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Term
| in the primate study in which primates were immobilized and then encouraged to exercise a lot for a year, what was the effect of exercise on bone after one year? |
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Definition
| the bone was stronger than it had been even before the period of immobilizatoin. There will be fewer avulsion fractures than initially |
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Term
| what are the effects of mobilization on insertion sites? |
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Definition
| psotive effect on mechanical properties, but not as extreme as the negative effects of immobilization. Less demonstrable effects on the histologic apeparance of inserting tissues compared with effects of immobilization |
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Term
| is ligament or insertion site recovery faster following immobilization? |
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Definition
| ligament reovery is faster than insertion site recovery after immobilization |
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Term
| how does age affect insertion sites? |
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Definition
| greater incidence of epiphyseal avulsions if plates are still open, more mid-substance failures once plates close, more avulsion fractures in individuals over 50 |
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Term
| describe the epiphyseal avulsion that can occur if plates are still open |
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Definition
| Type I Salter Harris = shearing of epiphysis on metaphysis |
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Term
| what might cause an avulsion fracture in a healthy not old adult? |
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Definition
| strain rate, immobilization, loading direction |
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Term
| why is there a greater incidence of avulsion fractures in individuals over 50? |
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Definition
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Term
| what to look for in possible avulsion fracture |
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Definition
| tenderness at the insertion site |
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Term
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Definition
| chronic inflammatory response at apophyseal growth plate where tendon or ligament attaches to bone. |
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Term
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Definition
| rest, ice NSAIDs. Stop the activity for a while. |
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Term
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Definition
| too much magnitude, frequency, duration of tugging of tendon or ligament force |
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Term
| what are common locations of apophysitis |
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Definition
| tibial turbecle, humeral epicondyle, ASIS< AIIS, ischial tuberosity, iliac crest, calcaneus, base of the 5th metatarsal |
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Term
| what is the name of apophysitis of the calcaneus |
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Definition
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Term
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Definition
| The apophyseal palte region where th pwerful soft tissue inserts becomes inflamed and very, very weak. It's painful, limiting. Can cause avulsion because of weakness and a big force. |
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Term
| what to say to a child/parent/coach who has apophysitis |
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Definition
| the child needs to rest. Can't play. Risk of avulsion. |
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Term
| how might a soccer player with apophysitis get an avulsion of rectus femoris? |
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Definition
| trying to kick ball but catching cleat in the ground: distal end can't move, so the proximal end is ripped from the pelvis |
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Term
| what might cause an ischial tuberosity apophyseal traction fracture? |
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Definition
| young gymnats or other athelte secondary to powerful eccentric activation in hamstring muscles |
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Term
| what muscles's powerful eccentric contraction can case base of 5th metatarsal apophyseal tractionf racture |
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Definition
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Term
| what is a segond fracture |
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Definition
| apophyseal traction fracture at the tibial insertion of LCL with internal rotation and varus |
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Term
| what to look for in someone with Segond fracture |
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Definition
| associated injuries to ACL and meniscus |
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Term
| What might cause an ASIS apophyseal traction fracture |
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Definition
| sartorius or TFL with foreful trunk rotation to the contralateral side resulting in lateral displacement of the avulsion. Could happen in baseball and hitting the ball. Could be rectus with pwoerful hip flexion such as soccer player who kicks the ground |
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Term
| what is Sinding-Larson-Johannson syndrome |
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Definition
| apophysitis at the inferior pole of the patella. Caused by repetitive jumping and landing |
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Term
| what are predisposing factors for apophyseal traction fractures |
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Definition
| MOI with too much magnitude, duration, frequency |
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Term
| what are histological predisposing factors for apophyseal traction fractures |
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Definition
| histological changes at the insertion site as it transitions from cartilaginous plate to mature bone. Just before this transition, there is a replacement of fibrocartilaginous cells to columnated bone cells. This region has decreased ability to resist tensile stress. If there is also an inflammatory process and weakening of the site, the region is predisposed to a traction/avulsion injury. |
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Term
| what are repair strategies for non-displaced apophyseal traction fractures |
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Definition
| often non-surgical. Reduced activity level. No tugging at all. NWB. Muscles must be totally quiet. Recovery must be gradual over a long period of time. |
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Term
| how to repair a displaced apophyseal traction fracture |
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Definition
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Term
| when a skeletally immature patient has a joint injury, what do you need to do |
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Definition
| rule out epiphyseal infjury |
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Term
| when an older individual has an injury related to inserting tissue, what do you need to do |
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Definition
| rule out avulsion fracture |
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Term
| what to consider for insertion sites following periods of immobility |
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Definition
| slow, progressive return to functional loading |
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