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57 Cards in this Set
- Front
- Back
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joints of the knee
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1. tibiofemoral (proximal tibia and distal femur)
2. patellofemoral (posterior patella and femur) |
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what type of joint is the tibiofemoral joint
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-double condyloid joint
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what motions is the tibiofemoral joint responsible for?
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1. flexion/extension
2. medial/lateral rotation 3.abduction/adduction |
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what bones are involved in the tibiofemoral joint?
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1. femur (large medial and lateral condyles)
2. tibia (slightly convex tibial plateaus; menisci are necessary to improve joint congruence) |
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what is the flexion/extension of tibiofemoral joint?
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initial flexion (0-25 degrees) that is produced by rolling of femur (fixed tibia)
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what is the ROM of flexion/extention of tibofemoral joint?
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ROM: 0-140 degrees
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what is medial/lateral rotation of tibiofemoral joint?
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Medial compartment is
axis of rotation • Medial meniscus reduces friction • Permitted by articular incongruence and ligament laxity • Most rotation available at 90° knee flexion • 20° lateral • 15° medial |
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what is the valgus/varus of tibofemoral joint?
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< 20° total
• Greater motion during flexion • Excessive motion may indicate ligamentous instability • OR lack of neuromuscular control |
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what is the screw home (locking mechanism)?
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• Obligatory lateral rotation
of tibia • Near end range knee extension (30-0°) • Shorter lateral tibial plateau and lateral femoral condyle completes rolling motion before longer medial structures • Opposite occurs with extension |
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screw home locking mechanism
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knee is consistantly rotating through medial aspect
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Patellofemoral joint
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congruence between patella and femur changes throughout ROM
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when is their minimal joint congruence in the patellofemoral joint?
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near full extension
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what does progressive flexion do in the patellofemoral joint?
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progressive flexsion to 90 degrees increases contact area inferior to superior
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what are the patellofemoral joint motions?
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flexion/extention
medial/lateral tilt (named for anterior surface movement) medial/lateral rotation (follows tibia) |
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what type of bone is the patella?
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largest sesamoid bone in the body
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what does the patella do?
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Lengthens moment arm (MA)
of the quadriceps • Increases the distance of the quadriceps tendon and patellar tendon (ligament) from the axis of knee joint • Acts as anatomical pulley • Deflects action line away from joint center • Increasing angle of pull • Increases ability of muscle to generate torque |
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what is the patella's influence on quadriceps function?
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• Peak torque 45-60° knee flexion
• Length tension relationship • Moment arm • Important at end range extension (0-15°) • Quadriceps in shortened position • Relative size of moment arm is critical |
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what is the orientation of femur?
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• Inferior and medial
orientation (~5°) |
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what is the orientation of the tibia?
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Vertical orientation
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what is the knee characterized by?
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valgus
• 185° angle • > 185° genu valgus • < 175° genu varum |
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what is grf?
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ground reaction force
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when are we typically in unilateral stance?
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when we are walking
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Unilateral stance the
GRF passes through medial compartment what is the consequence? |
bow legged or opposite
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what is the quadriceps angle?
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• Two line connecting
three points • ASIS • Midpoint of patella • Tibial tubercle • Normal: 10-15° |
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what influences the forces of the patellofemoral joint forces?
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Can be influenced by any combination of large joint forces or small contact area
• Knee angle • Quadriceps tension |
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as increase knee flexion angles...
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...we have increased contact area (up to about 90 degrees)
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what aspect of patella has greater stress?
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medial aspect
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how much extra body weight does patellofemoral joint reach with running and jumping?
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5-6x body weight
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what is dynamic valgus
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hip IR couples with knee ER
Increased patellofemoral contact forces • Potential pain generator |
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what is the menisci?
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• Fibrocartilaginous disk
• Medial- C shape • Lateral- 4/5 of circle • Cover 1/2 to 2/3 articular surface of tibial plateau • Lateral meniscus covers greater portion of smaller tibial surface • Thicker along periphery |
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what amount of surface does the menisci cover?
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1/2 to 2/3 of articular surface of tibial plateau
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what part of the meniscus covers greater portion of smaller tibial surface?
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lateral meniscus
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where is the menisci thicker?
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along the periphery
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what part of menisci has neurovascular supply?
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outer 1/3
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when does neurovascular supply decrease?
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decreases with age (after 50 y/o only periphery is vascularized)
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what is the central portion of menisci for?
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Central portion relies on diffusion of
synovial fluid for nutrient exchange • Requires intermittent loading |
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what is the function of menisci function?
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improve tibiofemoral congruence
-forms concavities for femoral condyles -increased contact area -Distribute weight bearing forces (50-70% load) -reduce friction |
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what is consequence if someone doesn't have a meniscus?
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bone degeneration ( greater osteoarthritis onset)
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Meniscectomy
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Contact area in tibiofemoral joint is
decreased • Pressure= force/area • 2x articular cartilage stress • 6-7x greater tibial plateau stress |
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the joint capsule in the knee is
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the largest in the body
-encloses tibiofemoral and patellofemoral joints -provides significant protion of knee and joint stability (restricts excessive joint motion) (reflexive muscular response) -deep layer is synovial layer (secrete and absorb synovial fluid) |
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what are the ligaments of the knee?
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• Bony restraint to movement in limited
• Ligaments provide stability to knee joint • Medial collateral • Lateral collateral • Anterior cruciate • Posterior cruciate • Prone to injury • Knee joint is between two long levers |
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Medial Collateral Ligament
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• Superficial and deep
portion • Primary restraint to valgus and lateral rotation • Taut in full extension • Secondary restraint to anterior tibia translation • Good blood supply • Capacity to heal- slowly |
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does the MCL have a good blood suppl?
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yes but capacity to heal is SLOW
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Lateral Collateral Ligament
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• Primary restraint to
varus stress • Taut in full extension • Secondary restraint to excessive lateral rotation of the tibia |
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Anterior Cruciate Ligament
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• Anteromedial and
posterolateral bands • Primary restraint to anterior translation of tibia on femur • AMB taut in flexion • PLB taut in extension • Secondary restraint for knee hyperextension, varus, and valgus |
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Posterior Cruciate Ligament
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• Primary restraint to
posterior tibial translation on femur • Able to withstand forces during knee flexion • Secondary restraint to varus and valgus |
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what are the knee joint muscles?
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• Extensors
• Quadriceps • Rectus Femoris • Vastus Medialis • Vastus Lateralis • Vastus Intermedius • Articularis Genu • Flexors • Hamstrings • Semitendinosus • Semimembranosus • Biceps Femoris • Sartorius • Gracilis • Popliteus • Gastrocnemius • Plantaris |
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what are the extensors of knee joint?
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• Quadriceps
• Rectus Femoris • Vastus Medialis • Vastus Lateralis • Vastus Intermedius |
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what are the flexors of knee joint?
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Hamstrings
• Semitendinosus • Semimembranosus • Biceps Femoris |
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what is the joint forces and exercise for weight bearing?
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• Minimal anterior shear
• Less stress s/p ACL-R • Posterior shear force at knee • Peak 80-105° • PFJ stress ↑ with ↑ knee flexion angles |
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what is the joint forces and exercise for non-weight bearing?
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• Anterior shear 40-0°
• ↑ PFJ stress • Posterior shear 60-100° |
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how many acl injuries are there in the US?
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100,000
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what occurs during an ACL injury?
(dynamic valgus is an issue) |
• Hip adduction and internal
rotation knee valgus and tibial external rotation (Ireland et al, 2002; Leetun et al, 2004) • Female 4-6x greater risk |
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what occurs during collateral ligament injuries? (LCL/MCL)
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typically due to contact mechanism
(MCL tend to happen more than LCL because of point of contact) |
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what injuries in knee are typically non surgical repairments?
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Collateral Ligaments (LCL/MCL)
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PFPS (patella femoral pain syndrom)
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• Knee pain with insidious
onset • Does not include ITBS, meniscus, patellar tendon • 2 or more • Patella compression • Squatting • Prolonged sitting • Going up or down stairs • Isometric quadriceps contraction • Common running injury (20%) • Females > Males • Muscle weakness and inhibition • Hip musculature (extensors, abductors, external rotators) |
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knee osteoarthritis
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• Kellgren-Lawrence Scale
• Five grades (0 normal to 4 severe) • Function prior to TKA is best predictor for success • Early rehab • Following TKA • Weight-bearing as tolerated (cemented fixation) • Improve LE strength |
