Download Knee Anatomy and Injuries

Knee Anatomy and Injuries
Bones of the knee:
- patella – sesamoid, free floating
bone
- tibia – main weight bearing bone
- fibula – attachment point for
muscles
- femur – largest bone, articulates
with the tibia
Major ligaments:
- Posterior cruciate ligament
(PCL)
- Anterior cruciate ligament (ACL)
- Medial collateral ligament
(MCL)
- Lateral collateral ligament (LCL)
Major muscles of the knee:
- Quadriceps: knee extension
o Rectus femoris
o Vastus lateralis
o Vastus medialis
o Vastus intermedius
- Hamstrings: Knee flexion
o Semimembranosus
o Semitendinosus
o Biceps femoris
-Gastrocnemius: knee flexion
- Popliteus: medial rotation
Common Mechanisms of Injury:
- Hyperextension / rotation
- valgus force
- varus force
Special Tests:
1. Lachman’s test – tests the ACL
in an acute situation
a. More comfortable position
(10-15 degrees of flexion)
b. With one hand grasp the
thigh and with the other hand
grasp the proximal tibia.
c. Push down the femur/thigh
while pulling the tibia
forward
2. Anterior Drawer Test – also
tests the ACL
a. Knee is in 90 degrees of
flexion
b. Acts in direct opposition to
hamstrings
c. Must relax hamstrings in
order to get a valid test
d. Place thumbs on either side
of the patellar tendon
e. Place fingers around calf
muscle and pull forward
while sitting on patients foot
to keep from sliding
3. Valgus/Varus Stress Tests
a. Valgus – stresses the MCL
i. Proper hand position is
one hand on the medial
malleolus, while the
opposite hand is on the
lateral joint line applying
valgus force while pushing
gently
b. Varus – stresses the LCL
i. Proper hand position is
one hand on the lateral
malleolus while the
opposite hand is on the
medial joint line gently
applying varus stress
4. Meniscal tests
a. Apley’s compression test
i. Patient is lying prone with
knee flexed to 90 degrees.
Clinician pushes knee
down towards table while
externally rotating tibia.
Pain indicates possible
meniscus tear
b. McMurray’s test
i. Patient is lying supine with
hip flexed at 90 degrees
and knee flexed at 90
degrees. The clinician
slowly extends knee while
externally rotating tibia
with fingers at the medial
and lateral joint line
feeling for clicking or
popping.