Knee - Anatomy & Biomechanics Flashcards
Three joints of the knee = ?
Knee - Anatomy & Biomechanics
Joints of the Knee:
(1) Tibiofemoral Joint:
- Between the femur of the thigh and the tibia of the shank.
(2) Patellofemoral Joint:
- Between the aforementioned femur and the largest sesamoid bone in our body – the patella.
(3) Proximal Tibiofibular Joint:
- This bony attachment is instead built for stability, anchoring the fibula for muscle attachment.
- Distal & lateral two the two previously mentioned primary joints.
Tibiofemoral Joint
- Primary weight-bearing joint, that guides = ?
1st & 2nd
Knee - Anatomy & Biomechanics
Tibiofemoral Joint:
- Primary weight-bearing joint, that
guides
- 1st = Flexion/Extension
- 2nd = Int/Ext Rot
- Frontal Plane:
- Medial Condyle: Our primary weight bearing structure in the knee. It’s closer to our center of gravity, necessitating less medial/lateral translation of our COM to bear weight, so a more distal medial side biases this compartment to accept more load.
- More Distal
- Accepts Center of Gravity During Stance Phase
- Sagittal Plane:
- Longer by ½ in.
- Drives the Screw-Home Mechanism: About 80% of this coupling happens within the terminal 30d of knee extension, so this is primarily a “leg-straight” event.
- Tibial Plateau Declination
- Transverse Plane:
- Lateral Plateau
- Closer to Convex on Convex
- Lateral Tibial Plateau Smaller than Medial
Knee - Anatomy & Biomechanics
Knee - Anatomy & Biomechanics
Patellofemoral Joint Articulation
Tracking Pathway:
- Begins slightly _ ? _ to the femoral sulcus
- Lateral Contact guides the _ ? _
- Tracking forms a subtle _ ? _
Knee - Anatomy & Biomechanics
Patellofemoral Joint Articulation:
- Improves Mechanical Advantage of Quads (0-30)
- Tracking Pathway:
- Begins slightly proximal to the Femoral Sulcus
- Lateral Contact guides the Patellar to Full Contact at 30°
- Tracking forms a subtle C Pattern Lat/Med/Lat
Patellofemoral Joint Articulation
Tracking Forces:
- Walking = ? x BW
- Jogging = ? x BW
- Deep Squat = ? x BW
Knee - Anatomy & Biomechanics
Patellofemoral Joint Articulation:
- Tracking Forces:
- ½ BW Walking
- 7x BW Jogging
- 20x BW Deep Squat
- Improves Mechanical Advantage of Quads (0-30)
Patellofemoral Joint Articulation
Tracking Depends on = ?
Knee - Anatomy & Biomechanics
Patellofemoral Joint Articulation:
- Tracking Depends on:
- Bony architecture of femoral Sulcus/Patella
- Extensibility of the surrounding connective tissue
- Quadriceps Activation
- Improves Mechanical Advantage of Quads (0-30)
Patellofemoral Joint Movements
Movements include = ?
Knee - Anatomy & Biomechanics
Patellofemoral Joint Movements:
- Movements:
- Superior (Extension)/Inferior (Flexion) Glide
- Medial/Lateral Glide
- Medial/Lateral Tilt
- Medial/Lateral Rotation
Tibiofibular Joint
- Is WB or NWB = ?
- Situated _ ? _ to the Tibia
- _? _ nerve wraps around the Fibular Head
Knee - Anatomy & Biomechanics
Tibiofibular Joint:
- Non-Weight-bearing Joint:
- 3mm of Movement
- Functionally part of the Ankle
- Situated Posterior to the Tibia:
- Solution = 45° Anterior-Lateral/Posterior-Medial
- Fibular Nerve:
- Wraps around the Fibular Head
Anterior Cruciate Ligament
Dynamic Stability of the Knee:
- Load is highest in = ?
- Taut throughout = ?
Knee - Anatomy & Biomechanics
Anterior Cruciate Ligament:
- Dynamic Stability of the Knee:
- Load is highest In extension (Inverse of PCL)
- Taut throughout entire range
Anterior Cruciate Ligament
- ACL has ? distinct bundles
Describe them
Knee - Anatomy & Biomechanics
Anterior Cruciate Ligament:
- Two distinct Bundles: Named for where they attach on the tibia.
(1) Posterior-lateral: Extension, Thicker (Parallel)
- The larger of the two, the posterior lateral bundle accepts this force in an extended knee with both bundles running parallel.
(2) Anterior-medial: Flexion (Crossed)
- The anterior-medial bundle crosses over the other to accept more force as the knee moves into flexion.
Anterior Cruciate Ligament
- Primary Role = ?
- Secondary Role = ?
Knee - Anatomy & Biomechanics
Anterior Cruciate Ligament:
- Primary Role:
- Prevent anterior tibial translation
- 75% of Anterior Translation at 0°
- 85% at 30°
- Secondary Role:
- Secondary stabilizer of tibial rotation (IR>ER)
- Tertiary stabilizer of tibial external rotation (IR>ER)
- 30° most IR from ACL
- 20-50° most unstable 2nd to laxity from ACL/PCL
ACL and PCL have their greatest slack between = ?
Knee - Anatomy & Biomechanics
ACL and PCL have their greatest slack between 20 and 50d.
Anterior Cruciate Ligament
Explain the importance of the “Twisted Fiber” / Double helix orientation of the ACL = ?
Knee - Anatomy & Biomechanics
Anterior Cruciate Ligament:
- Stores Energy:
(a) Twisted Fibers:
- Allow diffuse insertions and compact midsection.
- 90° Helix Stores Energy During Loading
- - The helixed nature of these fibers store energy in flexion that is released into extension moments.
(b) Change of Fiber Orientation
- Origin Vertical
- Insertion Horizontal
- Vascularization:
- Middle Genicular Artery
Anterior Cruciate Ligament
- Is innervated by the ? nerve.
- Innervation of this structure is largely ? in nature.
Knee - Anatomy & Biomechanics
Anterior Cruciate Ligament:
- Tibial Innervation
(a) Innervation of this structure is largely proprioception in nature.
- Reflexively activates the hamstrings and quads
- Minimal pain fibers
Anterior Cruciate Ligament
Vascularization from the ? provides ample blood flow, which is all well and good, but it does lead to ? if the ACL is ever torn.
Knee - Anatomy & Biomechanics
Anterior Cruciate Ligament:
- Vascularization from the middle genicular artery provides ample blood flow, which is all well and good, but it does lead to significant swelling if the ACL is ever torn.
- Vascularization: Middle Genicular Artery.
Posterior Cruciate Ligament
- Originating off the _ ? _ , this ligament is _ ? _ than its ACL counterpart.
Knee - Anatomy & Biomechanics
Posterior Cruciate Ligament:
- Originating off the medial femoral condyle, this ligament is 20% bigger than its ACL counterpart and more isometric/less extensible when the knee moves.
- Load is Highest In Flexion (Inverse of ACL)
- Works with other structures to stabilize posterior translation
- Popliteus
- Meniscofemoral Ligaments
Posterior Cruciate Ligament
The PCL is loaded most when in _ ? _ and it’s primary job is to resist _ ? _ , especially when the knee is between ? _ d of flexion.
## Footnote
Knee - Anatomy & Biomechanics
Posterior Cruciate Ligament:
- PCL is loaded most when in flexion and it’s primary job is to resist posterior tibial translation, especially when the knee is between 70-90 d of flexion.
- Primary Role = Resist Posterior Tibial Translation.
- Most Challenged between 70-90 ° Flexion
- Taut Throughout Entire Range
- Secondary Role = Stabilize tibial external rotation