The Knee Flashcards
Which side of the distal femur has more contact with the patella?
Lateral (medial has more contact with tibia than patella)
Which tibial condyle is longer?
medial
Because the tibia is vertical and the femur is slightly oblique, what angle to they create in standing at the knee?
~185° (slight valgus)
What knee angle is considered genu valgum?
> 185°
What angle is considered genu varum?
< 175°
Describe the mechanical axis between the hip and ankle in both normal standing & single-leg standing. How might this be relevant for a patient that demonstrates genu varum/valgum?
- hip is aligned directly over the ankle in the absence of anatomical dysfunction
- mechanical axis shifts medially in SLS, since the hips shift position
- the shifting axis in SLS combined with genu valgum/varum can overload supporting structures in the knee
What connective tissue makes up knee menisci?
fibrocartilage
Contrast the shapes of the medial vs lateral meniscus.
lateral is o-shaped, medial is c-shaped
What are the beginning and end of the meniscus called?
anterior and posterior horns
What are the 3 zones of the knee meniscus? Describe their blood supply, respectively.
- red zone: outer third, receives blood from capsular arteries
- red-white zone: middle third, poor blood supply
- white zone: central third, poor blood supply
What portion of the knee menisci is separated from the capsule? What is its blood supply?
posterior lateral corner of the lateral meniscus is separated from the capsule by the popliteus tendon & is relatively avascular.
List 6 attachments of the lateral knee meniscus to nearby structures.
- anteriorly to medial meniscus (transverse ligament)
- to the patella via thickening of anterior capsule (patellomeniscal ligament)
- posteriorly to the popliteus
- posteriorly to the posterior cruciate ligament (PCL)
- medial femoral condyle (meniscofemoral ligament)
- edge of the capsule (coronary ligaments)
List 6 attachments of the medial knee meniscus to nearby structures.
- edge of the capsule (coronary ligaments)
- anteriorly to lateral meniscus (transverse ligament)
- to the patella via thickening of anterior capsule (patellomeniscal ligament)
- posteriorly to semimembranosus muscle
- anterior horn attaches to the anterior cruciate ligament (ACL)
- posterior horn attaches to the posterior cruciate ligament (PCL)
Which knee meniscus is more mobile?
lateral meniscus
Describe the muscular attachments that can create movement of the knee menisci.
popliteus contractions can move the lateral meniscus, semimebranosus contractions can move the medial meniscus
List 4 functions of the knee menisci.
- increase contact area of femoral condyles on the tibial plateau
- assist with joint glide
- limit hyperextension
- provide cushion & support to the weight-bearing surfaces
Describe the innervation of the knee menisci.
nociceptors & joint mechanoreceptors (pain and proprioception can be altered after injury)
Describe the 3 regions of the lateral compartment of the knee and the reinforcing structures associated with each.
Anterior region: supported laterally by the lateral retinaculum
Middle region: reinforced by the distal ITB
Posterior region: reinforced by the arcuate complex
Describe the 2 layers of the lateral retinaculum. Which portion of the lateral knee compartment does the retinaculum reinforce?
- Superficial oblique layer: runs from the ITB to the lateral border of the patella & patellar tendon
- Transverse layer: undersurface of ITB to lateral patellar border
- reinforces the lateral portion of the anterior region of the lateral compartment
What 3 structures comprise the arcuate complex of the knee?
- lateral collateral ligament (LCL)
- arcuate ligament (reinforced by biceps femoris tendon)
- popliteus tendon
What are the attachments of the arcuate ligament of the knee?
posterior lateral femoral condyle to posterolateral tibia
What motions does the lateral collateral ligament of the knee restrain?
varus angulation of the tibia & excessive lateral rotation of the tibia
Describe how the contribution to knee stability provided by the LCL changes depending upon knee position.
- provides ~55% of the resistance to varus stress in 5° of flexion
- 69% with 25° flexion
(posterior structures are on slack in flexed position)
The posterior third of the medial compartment of the knee is reinforced by what two soft tissue structures?
- posterior oblique ligament (thickening of medial capsular ligament)
- semimembranosus muscle