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33 Cards in this Set
- Front
- Back
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What ligaments restrict excessive lateral rotation of the tibia?
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MCL and LCL
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What ligaments restrict excessive medial rotation of the tibia?
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ACL and PCL
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Describe the arthrokinematics of knee flexion in an CKC.
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The femoral condyles roll posteriorly and glide anteriorly
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What nerve roots innervate the biceps femoris (long head)?
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L5-S1,2
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What nerve roots innervate the biceps femoris (short head)?
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L5-S1,2
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Describe the shapes of the tibial condyles.
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The medial tibial plateau is concave, but the lateral is convex
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How does the lateral facet on the lateral femoral condyle differ from the medial facet?
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The lateral is higher thereby adding more stability as the patella tracks laterally during extension.
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Does the lateral meniscus attach to the LCL?
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No
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Which meniscus is more firmly attached to the tibial plateau?
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Medial
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What part of the meniscus has a blood supply?
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Lateral one third
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What role do the menisci play?
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Increase joint congruency, shock absorbance, they decrease friction
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What are the ramifications of a genu valgum deformity?
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MCL is stretched and the lateral meniscus is subjected to increase compression forces, increased lateral tracking of the patella
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What kind of force causes the LCL to become taut?
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Varus
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What kind of translation does the ACL control?
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Open kinetic chain-excessive anterior tibial Closed kinetic chain-excessive posterior of the femur
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At what degree does tibial rotation occur?
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90 degrees
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Describe the normal sequence of contact forces that occur at the patella.
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During knee flexion the contact forces progress from a superior to inferior direction.
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Describe the screw home mechanism.
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During knee extension in an open kinetic chain, the tibial rotates laterally
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What three factors contribute to the screw home mechanism?
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Shape of the MFC, Tension in the ACL, and lateral pull of the quads
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What is the Q angle and how is measured?
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The net lateral pull exerted on the patella by the quads. Axis-mid patella, proximal reference point- ASIS, distal reference point-tibial tuberosity
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What is a low positioned patella called?
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Patella baja
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What is the closed position of the knee?
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Extension
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What path does the patella normally take when doing from full flexion to extension?
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Lateral to medial to lateral
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What is the role of the patella?
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Increases the moment arm of the quads
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What structures apply lateral directed forces on the patella?
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IT band, Lateral patellar rectinaculum, quads
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What mechanism would cause the PCL to tear?
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Hyperflexion or dashboard injury
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What six factors contribute to excessive lateral tracking of the patella?
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Tight lateral structures, Excessive laxity in the medial structures, Bony dysplasia, abnormal patella position, knee malalignment, muscle weakness
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What muscle is considered the "key" to the knee?
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Popliteus
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What happens to the compression forces across the PF joint with squatting?
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They increase as the amount of squatting increases
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What is hyperextension of knee called?
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Genu recurvatum
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What structure is taut with genu recurvatum?
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Posterior capsule
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How would you actively insufficient the hamstrings?
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Ask the patient to actively extend the hip and flex the knee concurrently.
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What is an Extensor lag? |
The patient has full passive ROM but is unable to actively extend the knee from 30 to 0 degrees |
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How many degrees of motion can ocurr at the knee?
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3 Flex/ext, Varus/Valgus and Rotation
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