Orthopedic Management of the Knee Flashcards
References
Kisner and Colby, Chapter 21
Shankman, Chapter 18
fyi
The knee joint is designed for mobility and stability
What are some other things?
- It lengthens and shortens the LEs to raise and lower the body or to move the foot in space
- Supports body when Wbing
- Primary functional unit in walking, climbing and sitting activities
- The rotation that occurs between the femoral condyles and the tibia during the final degrees of extension is called ?
- When tibia is fixed, terminal ext results in the femur rotating internally
- As the knee is unlocked, the femur rotates laterally
locking
or
screw home mechanism.
If a patient lacks full hip extension (as with a hip flexion contracture), the patient cannot stand upright and lock the knee, thus lacking this passive stabilizing function?
the screw-home mechanism
- The primary function of the this is to increase the moment arm of the quadriceps muscle in its function to extend the knee.
- It also redirects the forces
the patella
The alignment of the patella in the frontal plane is influenced by what two things?
- line of pull of the quadriceps muscles group
- attachment to the tibial turbercle via the patella tendon.
the line of pull of the quadriceps muscles group and by its attachment to the tibial turbercle via the patella tendon.
The result of these two forces is a bowstring effect of the patella, causing it to track in which direction?
laterally
Increased Q angle occurs from ?
- wide pelvis
- Femoral anteversion
- Coxa vara
- Genu valgum
- Laterally displaced tibial tuberosity
Motions in transverse plane that may increase Q angle:
- External tibial rotation,
- Internal femoral rotation
- pronated subtalar joint
Functional knee valgus that occurs during dynamic activities can also?
increase Q angle
IT band and lateral retinaculum prevent ?
medial gliding of the patella
Tight ankle PF causes?
lateral displacement of the tibial tuberosity in relation to the patella
Do Tight HS muscles affect mechanics of the knee?
yes
what is VMO stand for ?
vastus medialis obliquus
Weakness or poor timing of VMO contractions increases?
the lateral drifting of the patella
Weak hip Abductors and External Rotators may result in ?
adduction of the femur and valgus at the knee under loaded weight bearing
During the normal gait cycle, the knee goes through a range of?
60 degrees (0 degrees extension at initial contact and 60 degrees at the end of the initial swing.
Muscles involved in knee control during gait:
- quadriceps
- hamstrings
- soleus
- gastroc
Because the knee is the joint between the hip and the foot, problems in these areas (hip/foot) can interfere with knee function. What are some problems?
- Hip flexion contractures
- Length and strength imbalances
- Foot impairments
Name the knee ligaments
- ACL
- PCL
- LCL
- MCL
- meniscus
If needed, review ligament healing in Shankman (Chapter 8)
fyi
- Injury often results in joint effusion
- Often referred to as “water on the knee” or “fluid in the knee”
ACL Tear-An intracapsular ligament
- Often non-contact
- Rotation of the tibia on a planted foot
- Can occur from forceful hyperextension
- Lateral blow to the knee (valgus force)
- Often occurs “terrible triad” or “unhappy triad”
ACL Tear’s MOI (Mechanism of Injury):
ACL Tear-S & S (signs and symptoms)
- Swelling
- Pain
- Instability (+ Lachman + anterior drawer)
Pg 293, Shankman
What test
- Patient supine
- Knee flexed to 25-30 degrees
- Stabilization of the femur with one hand and anterior/posterior translation of the proximal tibia with other hand
- Translation of the tibia should be less than 5 mm
- A 5mm-10mm translation is a (+) sign for ligament instability
Lachman
What test?
- Less reliable because ligament is relatively relaxed at 80-90 degrees of knee flexion
- Testing position
- Patient supine; knee flexed to 90 degrees
- Stabilization of affected limb by therapist sitting on foot
- Proximal tibia grasped with both hands with thumbs at the anterior joint line
- Anterior/posterior translation of proximal tibia
- Translation should be less than 5 mm
- A 5mm-10mm translation is a (+) sign for ligament instability
Anterior drawer test
ACL Tear-Conservative treatment
- Joint protection
- Activity modification
- Treat inflammation
- Exercise