THIGH & KNEE REGION Flashcards
joints of the knee
- Tibiofemoraljoint
- Patellofemoraljoint
- Superior tibiofemoral joint (separate to the knee joint)
Tibiofemoral joint:
femoral condyles + tibial plateau
bicondylar (predominantly uniaxial)
main movement in 1 plane; limited movement in orthagonal plane
- mainly F-E in the sagittal plane around a coronal axis
- limited rotation around vertical axis
- longer articular surface on medial femoral condyle = when extending will cause medial rotation of femur on tibia (during weight baring eg sit > stand)
- screw-home mechanism
Normal frontal plane alignment:
5˚ anatomical genu valgus
• medial femoral condyle extends further distally
• shaft of femur inclined laterally
• femoral condyles in same transverse alignment
• brings feet closer to midline for bipedal gait
Alignment of the femoral condyles in the transverse plane:
determines the orientation of the flexion/extension axis of the knee
Distal femur
Distal portion of femoral condyles flat v’s anterior & posterior portions
Medial and lateral tibial slopes in the sagittal plane:
medial tibial plateau has greater slope/angle
Tibial slope = angle between line P & line A-B:
P = line perpendicular to the long axis of the tibial diaphysis (L) A-B = line from anterior tibial peak to posterior tibial peak
Tibiofemoral menisci:
Increase congruency / contact area between femoral condyles & tibial plateau
- decreases stress
- protects articular cartilage
- generally have fibrocartilage structure
- thickens as goes laterally
- withstrands shear forces, increases Contact area, decreases local focal points of stress
- fibrocartilage protects underlying hyline cartilage
knee meniscus
After total meniscectomy:
• contact areas decreased ~75%, and PLCS increased ~ 235%
Medial meniscus - longer A-P & larger posterior horn
Lateral menisci - more variable & mobile
Meniscal coverage of plateau: medial 50-75%, lateral 75-93%
Tibiofemoral ligaments:
No bony stability: ligamentous and muscular support 1. Tibial collateral 2. Fibular collateral 3. Anterolateral 4. Anterior cruciate 5. Posterior cruciate (Iliotibial band)
- Tibial collateral ligament (TCL)
Resists valgus
Superficial – longer & stronger; main
restraint to valgus throughout F
Deep – shorter; lower extension to failure; also resists ant translation of tibia
- Fibular collateral ligament (FCL)
- resists varus
- Anterolateral ligament (ALL)
- resists tibial IR in 30˚ F
- anterolateral stability
- Anterior cruciate ligament (ACL)
2 functional fibre bundles:
Posterolateral band (PLB) – largest, tightest in E Anteromedial band (AMB) – tightens in F
• resists anterior translation of tibia on femur
• resists posterior translation of femur on tibia
• rotation stability*
• resists valgus
• main limit (with menisci) to end extension
*Internal & external tibial rotation @ 10˚ & 30˚ F
- Anterior cruciate ligament (ACL) INJURIES
• often non-contact
• large valgus moment
• + tibial ER
• adolescence
• pivoting sports
• females 3-5x
The slope of the tibial plateau has a direct relationship with
anterior tibial translation during the transition
from non-weightbearing to weightbearing conditions.
- Posterior cruciate ligament (PCL)
Resists posterior translation of tibia on femur
• Resists femur moving forward on tibia
- Posterior cruciate ligament (PCL) INJURY
“dashboard”
• Hyperflexion or hyperextension
PCL tag test
PCL deficiency resulted in a posterior shift of the tibial resting position to 8.4 +/- 2.6 mm at 90˚ compared with the intact knee.
- need quads to be relaxed
patellofemoral joint
articulates with patella surface of distal femur
- little contact in ext, increases in flx
translations
Patella glides distally on the femur during knee flexion.
The patella glides medially during 0-30˚ flexion then laterally during 30-90˚ flexion.
rotations
The patella flexes and
laterally tilts during knee flexion.
Contact area location & amount change through range F/E
• with increasing knee F contact moves proximally and increases
patella alters the line of action of the quadriceps group and increases in moment arm
patella alters the line of action of the quadriceps group and increases in moment arm
Anterior thigh:
Sartorius Quadriceps femoris - Rectus femoris (RF) - Vastus intermedius (VI) - Vastus lateralis (VL) - Vastus medialis * longus (VML) * obliquus (VMO) • Patellofemoral • Patella tendon • Tibial tuberosity
Posterior thigh:
Semimembranosus Semitendinosus - Hip E + Kn F - Tibial IR Proximal tendon • Musculotendinous junction - causes problems in sprinters Biceps femoris - long head: Hip E + Kn F - short head: Kn F - tibial ER
Posterior leg:
Gastrocnemius
plantaris
popliteus
Medial tibia to lateral femoral condyle
- unlocking knee joint
Screw home mechanism (IR femur on tibia)
- lateral rotation of the femur on the tibia unlocks the extended knee
Medial thigh & knee:
pes anserinus: insert on anteromedial tibia
- sartorius
- gracilis
- semitendinosus
“lateral thigh” & knee:
TFL
Biceps Femoris: Long and Short head
Iliotibial tract: inserts on girdle tubercle
