Knee + Shoulder, Elbow B&B Flashcards
the ACL runs from the ____ to the _____
the PCL runs from the ____ to the _____
the ACL runs from the lateral femoral condyle to the anterior tibia
the PCL runs from the medial femoral condyle to the posterior tibia
valgus vs varus deformities of the knee are resisted by which ligaments, respectively?
valgus = knock-kneed (lower leg abducted), resisted by MCL (medial collateral ligament)
varus = bow-legged (lower leg adducted), resistant by LCL (lateral collateral ligament)
the MCL runs from the ____ to the ____
the LCL runs from the ____ to the ____
the MCL runs from the medial epicondyle of the femur to the medial condyle of the tibia
the LCL runs from the lateral condyle of the femur to the head of fibula
a positive “anterior drawer sign” is diagnostic of what kind of tear?
ACL injury
when patient is supine, bend knee at 90* angle and pull tibia forward - if forward movement is greater than normal there is an ACL tear, because the ACL resists anterior forward movement of tibia
what is the classic cause of a PCL tear?
“dashboard injury” - due to car crash, knee gets thrown into dashboard, which causes lower leg to get pushed back
PCL tears often occur via trauma/force directed posteriorly at knee (contrast to ACL tears which area usually due to change of direction, non-contact)
what is the McMurray Test used for?
diagnosing meniscus tear
while patient is supine, the bent knee is held and extended while rotating the foot - if there is pain or a “pop” sound, there is a tear
internal rotation of the tibia tests lateral meniscus, external rotation of tibia tests medial meniscus
what kind of joint is the knee?
synovial - contains synovial fluid inside membrane, surrounded by bursa
there are 4 bursa around the knee
A woman presents to her GP with knee pain. On PE, the knee appears swollen and warm anterior to the patella. The patient says the pain comes with activity. She works as a housemaid. What is the most likely diagnosis and how can it be treated?
prepatellar bursitis - “housemaid’s knee” because it is often caused by repeated kneeling, can also be caused by infection or gout
treat with NSAIDs
where do Baker’s Cysts occur?
aka popliteal cysts, occur when fluid collects in the gastrocnemius-semimembranosus bursa at the back of the knee
often communicates with synovial space, related to chronic joint disease/ common in patients with rheumatoid arthritis
rupture may cause acute pain that mimics DVT
Patient with PMH of rheumatoid arthritis presents to the ED with acute leg pain. A colleague of yours is worried it may be DVT, though you think imaging will reveal…
Baker’s Cyst: aka popliteal cysts, occur when fluid collects in the gastrocnemius-semimembranosus bursa at the back of the knee
common in patients with rheumatoid arthritis, rupture may cause acute pain that mimics DVT
Osgood-Schlatter Disease
aka tibial tuberosity avulsion - pain/swelling at tibial tuberosity that occurs in children due to overuse
tibial tuberosity is insertion point of patellar tendon and secondary ossification center of tibia
benign, self-limited
what can patients with a patellar fracture NOT do?
extend knee against gravity
this is because patella connects quads tendon above to patellar ligament below, which attaches to lower leg - if there is a fracture, the force cannot be transmitted across the knee
what are the 4 muscles of the rotator cuff?
- supraspinatus - initiates abduction, most common rotator cuff injury
- infraspinatus - assists in external rotation and abduction
- subscapularis - assists in internal rotation of shoulder/arm
- teres minor - assists in external rotation and adduction
tendonitis of the rotator cuff will cause pain with [adduction/abduction]
abduction - the rotator cuff prevents the shoulder from popping out when the arm is moved away from midline
what is the most commonly injured muscle of the rotator cuff and how does this typically occur?
supraspinatus - initiates abduction (away from midline), injury usually via impingement of tendon between humeral head and acromion process of scapula
“swimmer’s shoulder” or “thrower’s shoulder”
what does the empty/full can test diagnose?
identifies supraspinatus injury, most common injury of rotator cuff, usually via impingement
empty can test (arm out and slightly in front with thumb down) / full can test (arm with thumb up) —> pain with pressing down = positive test
which nerves innervate each muscle of the rotator cuff? (4)
- supraspinatus - suprascapular nerve
- infraspinatus - suprascapular nerve
- teres minor - axillary nerve
- subscapularis - upper/lower subscapular nerves
all come from brachial plexus!
which 3 muscles are involved in shoulder abduction, and what are their respective roles?
- supraspinatus - initiates abduction, first 15 degrees
- delotid - primary abductor, up to 90 degrees
- trapezius/serratus anterior - abduction beyond 90 degrees
shoulder dislocations commonly injure which nerve? which muscle will this affect most?
axillary nerve - runs below humeral head and wraps around neck of humerus
causes sensory loss of deltoid muscle —> weak abduction
tennis elbow vs golfer’s elbow
tennis elbow - lateral epicondylitis of humerus, elbow pain with resisted wrist extension
golfer’s elbow - medial epicondylitis of humerus, elbow pain with resisted wrist flexion
nursemaid’s elbow
aka radial head subluxation (partial dislocation)
caused by axial traction on pronated forearm (like a child yanking on an arm) —> annular ligament slips over head of radius and becomes trapped in radiohumeral joint
most common pediatric elbow fracture
supracondylar fracture - just above condyles, in distal part of humerus (just above elbow joint)
brachial artery and median nerve may be injured!
