First Aid USMLE Step 1: MSK &
Dermatology
Knee Anatomy: - answer:-
What does the ACL connect?
What does it prevent? - answer:-- Extends from the lateral femoral condyle to the
anterior tibia
- Prevents anterior translocation at the knee joint
What does the PCL connect? - answer:-Extends from the medial femoral condyle to the
posterior tibia
Anterior Drawer Sign
What does it test for?
How do you perform it and when is it positive?
What is a similar test that tests for the same thing? - answer:-What does it test for?
- Tear of the ACL
How do you perform it?
- Bending knee at 90 degree, pull knee anteriorly
- Increased anterior gliding of the tibia seen in ACL injury
Note: Lachman test is similar but at 30 degree angle
Posterior Drawer Sign
What does it test for?
How do you perform it? - answer:-What does it test for?
- Torn PCL
How do you perform it?
- Bend knee at 90 degree
- Increased posterior gliding of tibia = PCL injury
Abnormal Passive Abduction of the knee (VALGUS stress test)
What does it test for?
How do you perform it? - answer:-What does it test for?
- MCL tear
How do you perform it?
- Knee extended or at 30 degree, apply force laterally (VALGUS/external rotation) while
stabilizing knee
,First Aid USMLE Step 1: MSK &
Dermatology
- If there is medial space widening --> MCL injury
Abnormal Passive Adduction of the knee (VARUS stress test)
What does it test for?
How do you perform it? - answer:-What does it test for?
- LCL tear
How do you perform it?
- Knee extended or at 30 degree, apply force medially (VARUS/internal rotation) while
stabilizing knee
- If there is lateral space widening --> LCL injury
McMurray Test
What does it test for?
How do you perform it? - answer:-What does it test for?
- Meniscal injury/tear
How do you perform it?
- Flexion and extension of knee with rotation of the tibia/foot
IF pain, "popping" on *external* rotation --> *Medial* meniscal tear
IF pain, "popping" on *internal* rotation --> *Lateral* meniscal tear
Knee Anatomy - answer:-
What is a greenstick fracture? - answer:-An incomplete fracture extending partway
through the width of the bone following bending stress; bone is bent like a green twig
What is a torus fracture? - answer:-Axial force applied to immature bone leads to a
simple buckle fracture of the cortex. Can be very subtle.
What is the "unhappy triad" knee condition caused by?
What is injured?
How does it present? - answer:-What is the "unhappy triad" knee condition?
- Common injury in contact sports due to *lateral* force applied to a planted leg
What is injured?
- Classically consists of damage to the *ACL, MCL and menial meniscus*
,First Aid USMLE Step 1: MSK &
Dermatology
- However, damage to the *lateral meniscus is more common*
How does it present?
- Acute knee pain and signs of joint injury and instability
Osgood Schlatter's Disease:
What is it?
What causes it?
What can it cause?
txt? - answer:-Common cause of knee pain in growing adolescents
- Overuse injury
- *Inflammation of the patellar tendon at the tibial tubercle*
- May cause tendon to pull away from the tubercle
- "Knobby knees"
Treatment: Conservative
- Rest, ice, stretching
- Braces
What is prepatellar bursitis?
What causes it? - answer:-What is prepatellar bursitis?
- Inflammation of the perpatellar bursa in front of the kneecap. AKA inflammation of the
knee's largest sac of synovial fluid
What causes it?
- Repeated trauma or pressure from excessive kneeling; also called "housemaid's knee"
What is a Baker's Cyst?
What does it communicate with?
What is it related to? - answer:-What is a Baker's cyst?
- Popliteal fluid collection in the gastrocnemius-semimembranous burse
- Commonly communicates with the synovial space and is related to chronic joint
disease
What are the muscles of the rotator cuff?
What spinal nerve roots are primarily responsible for their innervation? - answer:-*What
are the muscles of the rotator cuff?*
- SITS (AEEI)
- Supraspinatus
, First Aid USMLE Step 1: MSK &
Dermatology
- Infraspinatus
- Teres minor
- Subscapularis
What spinal nerve roots are primarily responsible for their innervation?
- C5-C6
Most commonly injured rotator cuff muscle?
Most common way to injure that muscle? - answer:-Supraspinatous
Trauma, degeneration and impingement leading to --> tendinopathy/tear
Arm abduction muscles/innervation from 0-100+ degrees - answer:-0-15 degrees =
supraspinatus (suprascapular)
15-100 degrees = deltoid (axillary)
>90 degrees = trapezius (accessory)
>100 degrees = serratus anterior (long thoracic)
supraspinatus:
Action?
Innervation?
What test assesses for tear in this muscle? - answer:-- Initial ABduction of the shoulder
(before deltoid kicks in)
- suprascapular nerve
- Assessed by the "empty can test"
Infraspinatous:
Innervation?
Action?
Who is it classically seen in? - answer:-- Suprascapular nerve
- External (lateral) rotation
- Pitchers (Pitching injury)
Teres Minor:
Innervation?
Action? - answer:-- Axillary nerve
Dermatology
Knee Anatomy: - answer:-
What does the ACL connect?
What does it prevent? - answer:-- Extends from the lateral femoral condyle to the
anterior tibia
- Prevents anterior translocation at the knee joint
What does the PCL connect? - answer:-Extends from the medial femoral condyle to the
posterior tibia
Anterior Drawer Sign
What does it test for?
How do you perform it and when is it positive?
What is a similar test that tests for the same thing? - answer:-What does it test for?
- Tear of the ACL
How do you perform it?
- Bending knee at 90 degree, pull knee anteriorly
- Increased anterior gliding of the tibia seen in ACL injury
Note: Lachman test is similar but at 30 degree angle
Posterior Drawer Sign
What does it test for?
How do you perform it? - answer:-What does it test for?
- Torn PCL
How do you perform it?
- Bend knee at 90 degree
- Increased posterior gliding of tibia = PCL injury
Abnormal Passive Abduction of the knee (VALGUS stress test)
What does it test for?
How do you perform it? - answer:-What does it test for?
- MCL tear
How do you perform it?
- Knee extended or at 30 degree, apply force laterally (VALGUS/external rotation) while
stabilizing knee
,First Aid USMLE Step 1: MSK &
Dermatology
- If there is medial space widening --> MCL injury
Abnormal Passive Adduction of the knee (VARUS stress test)
What does it test for?
How do you perform it? - answer:-What does it test for?
- LCL tear
How do you perform it?
- Knee extended or at 30 degree, apply force medially (VARUS/internal rotation) while
stabilizing knee
- If there is lateral space widening --> LCL injury
McMurray Test
What does it test for?
How do you perform it? - answer:-What does it test for?
- Meniscal injury/tear
How do you perform it?
- Flexion and extension of knee with rotation of the tibia/foot
IF pain, "popping" on *external* rotation --> *Medial* meniscal tear
IF pain, "popping" on *internal* rotation --> *Lateral* meniscal tear
Knee Anatomy - answer:-
What is a greenstick fracture? - answer:-An incomplete fracture extending partway
through the width of the bone following bending stress; bone is bent like a green twig
What is a torus fracture? - answer:-Axial force applied to immature bone leads to a
simple buckle fracture of the cortex. Can be very subtle.
What is the "unhappy triad" knee condition caused by?
What is injured?
How does it present? - answer:-What is the "unhappy triad" knee condition?
- Common injury in contact sports due to *lateral* force applied to a planted leg
What is injured?
- Classically consists of damage to the *ACL, MCL and menial meniscus*
,First Aid USMLE Step 1: MSK &
Dermatology
- However, damage to the *lateral meniscus is more common*
How does it present?
- Acute knee pain and signs of joint injury and instability
Osgood Schlatter's Disease:
What is it?
What causes it?
What can it cause?
txt? - answer:-Common cause of knee pain in growing adolescents
- Overuse injury
- *Inflammation of the patellar tendon at the tibial tubercle*
- May cause tendon to pull away from the tubercle
- "Knobby knees"
Treatment: Conservative
- Rest, ice, stretching
- Braces
What is prepatellar bursitis?
What causes it? - answer:-What is prepatellar bursitis?
- Inflammation of the perpatellar bursa in front of the kneecap. AKA inflammation of the
knee's largest sac of synovial fluid
What causes it?
- Repeated trauma or pressure from excessive kneeling; also called "housemaid's knee"
What is a Baker's Cyst?
What does it communicate with?
What is it related to? - answer:-What is a Baker's cyst?
- Popliteal fluid collection in the gastrocnemius-semimembranous burse
- Commonly communicates with the synovial space and is related to chronic joint
disease
What are the muscles of the rotator cuff?
What spinal nerve roots are primarily responsible for their innervation? - answer:-*What
are the muscles of the rotator cuff?*
- SITS (AEEI)
- Supraspinatus
, First Aid USMLE Step 1: MSK &
Dermatology
- Infraspinatus
- Teres minor
- Subscapularis
What spinal nerve roots are primarily responsible for their innervation?
- C5-C6
Most commonly injured rotator cuff muscle?
Most common way to injure that muscle? - answer:-Supraspinatous
Trauma, degeneration and impingement leading to --> tendinopathy/tear
Arm abduction muscles/innervation from 0-100+ degrees - answer:-0-15 degrees =
supraspinatus (suprascapular)
15-100 degrees = deltoid (axillary)
>90 degrees = trapezius (accessory)
>100 degrees = serratus anterior (long thoracic)
supraspinatus:
Action?
Innervation?
What test assesses for tear in this muscle? - answer:-- Initial ABduction of the shoulder
(before deltoid kicks in)
- suprascapular nerve
- Assessed by the "empty can test"
Infraspinatous:
Innervation?
Action?
Who is it classically seen in? - answer:-- Suprascapular nerve
- External (lateral) rotation
- Pitchers (Pitching injury)
Teres Minor:
Innervation?
Action? - answer:-- Axillary nerve
