Pelvis, Hip, and Knee Flashcards
Lumbosacral joint
- Connected by a large intervertebral disc
- Transfers weight, along with the ilium
- Iliolumbar ligament
Posterior strength of lumbosacral joint comes from
- Interosseous
- Dorsal sacroiliac ligaments
Lumbosacral joint/ilium weight transfer
- While walking, transferred to the femur
- While sitting, transferred to the ischial tuberosities
Iliolumbar ligament
- Ventral and dorsal portion
- Restrains movement at the lumbosacral and sacroiliac joint
Pelvis in open kinetic chain
- The thigh moves on the hip joint
Pelvis in closed kinetic chain
- The hip joint moves on the thigh
Pelvis is made up of
- Sacrum
- Coccyx
- Pubis
- (Two os coxae = ishium, ilium and pubis)
Male pelvis
- Longer and more curved sacrum
- Narrow sub-pubic arch
Female pelvis
- Wider and broader
- Less prominent ischial spines
Sacroiliac joint
- Synarthrodial joint
- Allows little to no movement in adulthood
- Helps absorb the weight bearing load from the legs
Sacroiliac joint stability provided by
- Interosseous sacroiliac ligament (prevents anterior inferior ovemet of the sacrum)
- Posterior sacroiliac ligament
- Sacrotuberous ligament
- Sacrospinous ligament
Sacroiliac joint movement
- Anterior-posterior (sagittal plane)
- Movement limited to 2 to 4 mm due to architecture and ligamentous support
Pubic symphysis
- Cartilagenous synarthrodial joint
- Fibrocartilagenous interpubic disc
- Small amount of translation and rotation
Pubic symphysis resists
- Traction force inferiorly
- Compressive forces superiorly
- Shearing and compressive forces during stance
Pubic symphysis rotation
- Will rotate in tandem with the sacroiliac joint
- Can move ~2 mm with 1 degree rotation
Pubic symphysis support
- Supported by 4 ligaments
- Superior, inferior (arcuate), anterior and posterior pubic ligaments
Hip joint
- A ball and socket synovial joint
- Has three degrees of freedom
- Motion in all three cardinal planes
Hip joint stability provided by
- Anatomic shape
- Soft tissue attachments
Ischial component of acetabular fossa
- ~>2/5 total surface
- Lower and side boundaries
Ilial component of acetabular fossa
- ~<2/5 total surface
- Upper boundary
Pubis component of acetabular fossa
- Remainder of fossa that is not ischial or ilial
Parts of the acetabular fossa
- Hemispherical shape
- Sides lined with articular cartilage
- Acetabular notch (inferior, horse-shoe shaped)
- Acetabular labrum (upper, thick rim that deepens the fossa)
Acetabular fossa alignment
- Forward (30-40° from the frontal plane)
- Lateral
- Downward (30-40° (20-30°) from horizontal or transverse plane, roof overhangs head of femur)
Acetabular fossa function
- Allows for stability medially, superiorly and posteriorly
- Roof receives greatest pressure
- Difficult to dislocate
Acetabular labrum
- Fibro-cartilaginous rim attached to the margin of the acetabulum
- Deepens the acetabular cavity
Characteristics of acetabular labrum
- Horse-shoe shaped
- Ends contacted at the acetabular notch via transverse ligament
- Thicker posteriorly
- Wider and thinner anteriorly
Three extracapsular hip ligaments
- Iliofemoral
- Ischofemoral
- Pubofemoral
Iliofemoral ligament
- Y-shaped
- Strongest ligament in the body
- Tighter when hip is extended
Iliofemoral ligament extends from
- AIIS to intertrochanteric line
Iliofemoral ligament function
- Prevents hip hyperextension during standing
Pubofemoral ligament extends from
- Superior pubic rami to the intertrochanteric line
Pubofemoral ligament function
- Triangular shape
- Reinforces the joint anteriorly and inferiorly
- Prevents excessive abduction and extension
Ischiofemoral ligament extends from
- Body of ischium to the greater trochanter
Ischiofemoral ligament function
- Spiral orientation
- Prevents hyperextension
- Supports head of femur in acetabulum
Ligamentum teres extends from
- Ischial and pubic sides of acetabular fossa to the fovea capitus of the femur
- Encloses a branch of the obturator artery
Ligamentum teres function
- Stabilizes the hip in flexion
- Particularly in squatting position
Head of femur supported by
- Femoral neck (obliquely set)
- Angulation within frontal plane
Angle of femoral inclination
- Average adult = 128°
Angle of antetorsion
- Deviated 10-30° from the frontal plane
Femur sagittal plane contour
- Mild forward curvature
- Aided by pull of hamstrings
Femur frontal plane curvature
- Outward curvature of the head, neck and upper shaft
- Tensor fascia lata and vastus lateralis aid valgus curve of distal femur
Bending of the femur
- Only biarticular muscles can bend the femur
Factors that provide hip stability
- Shape of acetabular fossa
- Extracapsular ligaments
- Intracapsular ligaments
Hip joint frontal or lateral axis
- Projects to body’s surface near greater trochanter
- Flexion and extension of hip
Hip joint sagittal or anterior-posterior axis
- At groin, midpoint of inguinal line
- Abduction and adduction of hip
Hip joint vertical (mechanical) axis
- Line that connects femur’s points of contact with acetabulum and tibia
- Internal and external rotation of hip
Hip joint has 3 degrees of freedom
- Sagittal plane
- Frontal plane
- Transverse plane
Hip sagittal plane degree of freedom
- Flexion: 120 - 140 degrees
- Extension: 15 - 20 degrees
Hip frontal plane degree of freedom
- Abduction: 45 - 50 degrees
- Adduction: 20 - 30 degrees
Hip transverse plane degree of freedom
- Internal rotation: 45 degrees
- External rotation: 45 degrees
Transverse plane motion at hip
- Internal and external rotation
- Each more distal limb segment rotates in the same direction as the pelvis
- But, each distal segment rotates more than its proximal segment
Infant hip transverse plane range of motion
- 2-3:1 external to internal
- Total range up to 155°
- Decreases to 90° by age six
Adult hip transverse plane range of motion
- 1:1 external to internal
Total range ~90°
Geriatric hip transverse plane range of motion
- 2:1 external to internal
- Concomitant increased angle of gait
- Total range may be < 90°
1st element of gait
- Pelvic Rotation (transverse plane)
Ligamentous causes of femoral anteversion/retroversion
- Pubofemoral ligament
- Iliofemoral ligament
- Ligamentum teres
- Intrauterine position?
Muscular etiologies of femoral anteversion/retroversion
- Tight medial hamstrings
- Tight adductor muscles
Sagittal plane motion at hip
- Allows forward movement of leg
- Hip flexion and extension
- Moves from flexed to full extension in midstance
- Begins flexing during early propulsion
Frontal plane motion at hip
- Very slight movement during gait
- Abduction and adduction
- During gait, 5° drop on non-weight bearing side
- Mild abduction during early swing
2nd element of gait
- Pelvic list (frontal plane)
Angle of femoral inclination (Mickulicz angle)
- Relationship of the long axis of the head and neck to the long axis of the femoral shaft
Normal values of angle of femoral inclination (Mickulicz angle)
- Birth: 35 - 150°
- Adult: 120 - 132°
Hip positions in the stance phase of gait
- Heel strike: extended
- Loading response: mild flexion
- Midstance: extended
- Heel lift: extended
- Toe off: staring to flex
Hip positions in the swing phase of gait
- Early swing: flexed
- Midswing: flexed
- Terminal swing: extending
3rd element of gait
- Knee joint extension/flexion
Knee joint
- Complex hinge joint
- Endures the heaviest stresses of any joint
- Two degrees of freedom
Knee joint in extension
- Stabilizer
- Shock absorber
Knee joint in flexion
- Great mobility
- Helps foot to adapt to ground
- Shortens the limb
- Develops kinetic energy for running
Knee joint components
- Distal Femur
- Proximal Tibia (transfers weight across the knee and to the ankle)
- Patella
Knee joint horizontal frontal plane axis
- Runs through femoral condyles
- Sagittal plane motion (flexion and extension)
Knee joint vertical axis
- Transverse plane motion
- Movement in the final degrees of knee extension
Knee joint horizontal sagittal plane axis
- Potential frontal plane motion
- Generally pathologic
Bony features of distal femur (knee joint)
- Lateral and medial condyles
- Lateral and medial epicondyles
- Intercondylar notch
- Intercondylar (trochlear) groove
- Lateral and medial patellar facets
- Popliteal surface
Knee joint articular facets
- Two facets between femur and tibia
- One two-sided facet between patella and femur
- Medial and Lateral condyles are not symmetrical
Bony features of proximal tibia and fibula (knee joint)
- Head of fibula
- Medial and lateral condyles
- Intercondylar eminence (with tubercles)
- Anterior intercondylar area
- Posterior intercondlar area
- Tibial tuberosity
- Soleal line
Tibial plateau
- Medial facet
- Lateral facet
- Peripheral portions
Medial tibial facet
- Oval and concave
Lateral tibial facet
- Nearly circular
- Concave side to side
- Convex from posterior
Tibia peripheral portions
- Fibrocartilagenous minisci
Menisci properties
- Semi-lunar
- Poor vascular supply
- Disperse friction
- Shock absorbers
Medial meniscus
- Well attached
- Injured slightly more often
Lateral meniscus
- More mobile
Bony features of the patella
- Base
- Apex
- Anaterior surface
- Posterior articular surface
- Vertical ridge
- Lateral, medial and odd facet
Patella
- Patella = “small plate” in Latin
- Embedded within the quadriceps tendon
- Functions as a pulley
- Largest sesamoid in body
Patella is tethered by
- Patellar retinaculum
- Anchored inferiorly by patellar tendon
- Acts as a pulley to redirect the force of quadriceps contraction
Patella function
- It glides in the intercondylar notch
- This adjusts the oblique pull of the quadriceps
Lateral facet of posterior patella
- Broader and deeper
- Roughly 2/3 of patella
- Sagittal convexity
- Coronal concavity
Medial facet of posterior patella
- Narrower and shallower
- Smaller and slightly convex
Patellar movement in knee extension
- Inferior portion of patella has greatest contact with femur
Patellar movement in knee flexion
- Superior portion makes greatest contact with femur
Medial collateral ligament attachments
- Originates on medial epicondyle of femur
- Attaches to medial condyle of tibia
- Attached to joint capsule and medial meniscus
Medial collateral ligament fibers
- Anterior: tight with knee flexion
- Posterior: tighter with knee extension, shorter and more oblique
Lateral collateral ligament attachments
- Originates on lateral epicondyle of femur
- Attaches to fibula
Lateral collateral ligament fibers
- Tight only
- Knee joint extension beyond 150°
Anterior cruciate ligament function
- Resists excess sagittal plane movement
- Tight in full extension
- Resists anterior movement of tibia
- Tightens again with knee in full flexion
Anterior cruciate ligament attachments
- Anterior intercondylar area of tibia
- Medial posterior aspect of lateral femoral condyle
Posterior cruciate ligament function
- Resists excess sagittal plane movement
- Tightens with > 30° flexion
Posterior cruciate ligament attachments
- Posterior intercondylar area of tibia
- Lateral anterior aspect of the medial femoral condyle
Knee joint axis
- Moving axis, possesses two degrees of freedom
- Predominant motion: sagittal plane
- At end of knee extension: transverse plane motion to lock the knee
Knee joint sagittal plane range of motion
- Extension: to vertical; up 5° beyond vertical
- 130 - 135° flexion; limited by soft tissue impingement
Knee joint transverse plane range of motion
- Occurs during last 20° of knee extension
- When knee is flexed: up to 40°motion is available
- Locking mechanism of knee joint
Knee joint flexion in closed kinetic chain
- Femur rotates slightly lateral (relaxes LCL)
- Menisci pulled posteriorly
- PCL tightens
- Femur “rocks” on tibial plateau
- Tibia moves posteriorly
Knee joint flexion in CKC during gait cycle occurs during
- During propulsion after heel off but before toe off
- Limb is beginning to shorten for swing
Knee joint extension in closed kinetic chain
- Femoral condyles “roll” on tibial plateau
- Femur rotates slightly medial and posterior
- Medial condyle slides slightly posterior
- Collaterals pulled tight
- Tibia moves anteriorly
- ACL pulled tight
Locking mechanism of knee
- Occurs due to the shape and convexity of medial femoral condyle
- Facilitated by the quadriceps
- Lateral condyle begins internal rotation
- It occurs within the last 20° of knee extension
Unlocking of the knee
- The popliteus is the “key” to unlocking the knee
- It initiates lateral rotation of the femur to promote flexion
Knee frontal plane deviations
- Genu valgus (knock kneed)
- Genu varum (bow legged)
