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
Posterior Cruciate Ligament:
- The Anterolateral bundle taught during = ?
- The Posteromedial bundle is taught during = ?
Knee - Anatomy & Biomechanics
Posterior Cruciate Ligament:
- Two distinct Bundles:
- The thicker Anterolateral bundle taught during flexion.
- The Posteromedial bundle is taught during extension.
Posterior Cruciate Ligament:
The PCL works with what other structures to stabilize posterior translation = ?
Knee - Anatomy & Biomechanics
Posterior Cruciate Ligament:
- Works with other structures to stabilize posterior translation
Medial Collateral Ligament
- The MCL has two portions, what are they = ?
- As a unit, what do they work to prevent = ?t
Knee - Anatomy & Biomechanics
Medial Collateral Ligament: Limits valgus forces & movements.
- The superficial and deep MCL work together to limit valgus forces and positions acting upon the knee.
- Notes:
- The MCL is larger than the LCL
- Broader and Longer
- Bolstered by:
- Pes Anserine Muscles and Semimembranosus
- Two Portions
(1) Superficial MCL
- Primary stabilizer of Valgus Stress
- Taut at End-ranges
- Semimembranosus & Posterior Oblique Ligament
(2) Deep MCL
- Stabilizes Valgus and may help to control anterior translation
- Taut in Extension
- Meniscofemoral and Menisotibial ligaments
Medial Collateral Ligament
The LCL is bolstered by _ ? _ and _ ? _ , which when active, more than double the tensile strength of the MCL.
Knee - Anatomy & Biomechanics
Medial Collateral Ligament:
- Bolstered by Pes Anserine muscles, and semimembranosus.
Medial Collateral Ligament
- The two portions of the MCL = ?
- Taught in = ?
- What are some connections to both = ?
Knee - Anatomy & Biomechanics
Medial Collateral Ligament:
- Two Portions:
(1) Superficial MCL:
- Primary stabilizer of Valgus Stress
- Taut at End-ranges - most so in extension
- Semimembranosus & Posterior Oblique Ligament
(2) Deep MCL:
- Stabilizes Valgus and may help to control anterior translation
- Taut in Extension
- Meniscofemoral and Menisotibial ligaments
Medial Collateral Ligament
The superficial MCL, is the primary component of the structure, bolstering the joint against valgus loads, especially at end-ranges, and the most so in ?
Knee - Anatomy & Biomechanics
The superficial MCL, is the primary component of the structure, bolstering the joint against valgus loads, especially at end-ranges, and the most so in extension.
Medial Collateral Ligament
This superficial MCL, being about an inch thick, runs from the _ ? _ and fans out over the _ ? _ .
Knee - Anatomy & Biomechanics
- This superficial MCL, being about an inch thick, runs from the medial femoral epicondyle and fans out over the medial tibia.
- It connects to the semimembranosus via the posterior oblique ligament.
Lateral Collateral Ligament
Lateral Collateral Ligament:
- Resists _ ? _ forces = ?
- Bolstered by the _ ? _ and _ ? _
Knee - Anatomy & Biomechanics
Lateral Collateral Ligament:
- Resists Varus Forces
- Smaller than the MCL
- Bolstered by the Anterolateral Ligament (poor mans ACL), which
- Controls tibial internal rotation
- Controls anterior tibial translation
- Bolstered by the Iliotibial Band (Teal)
- Diffuse Insertion:
- Femur
- Patella
- Tibia (Gerdy’s Tubercle)
The LCL runs from the _ ? _ of the femur, just proximal to the popliteus, all the way down to the _ ? _ .
Knee - Anatomy & Biomechanics
The LCL runs from the lateral epicondyle of the femur, just proximal to the popliteus, all the way down to the fibular head.
Lateral Collateral Ligament
Integrity of the _ ? _ is thought to help determine the success of ACL recovery in some patients.
Knee - Anatomy & Biomechanics
Lateral Collateral Ligament:
Integrity of the anterolateral ligament is thought to help determine the success of ACL recovery in some patients.
Lateral Collateral Ligament
The ITB is unique in how much it fans its insertion over several structures, casting its retinaculum over the _ ? _ , _ ? _ , and of course, _ ? _ .
Knee - Anatomy & Biomechanics
Lateral Collateral Ligament:
- LCL, bolstered by the IT band, which has a diffuse Insertion on:
- Femur
- Patella
- Tibia (Gerdy’s Tubercle)
- The ITB is unique in how much it fans its insertion over several structures, casting its retinaculum over the femur, patella, and of course, Gerdy’s tubercle.
- While the LCL might not be damaged as often as the MCL, or frankly as cool of a structure, it still is important for knee stability.
Posterior Knee
Think of physiologic holes in the posterior capsule as a release valve for Synovial fluid; _ ? _ may appear when there is too much swelling.
Knee - Anatomy & Biomechanics
Posterior Knee:
- Durable Structure =
- Thick Posterior Capsule
- Oblique Popliteal Ligament (Pink)
- Release Valve for Synovial Fluid
- Physiologic Holes in the Posterior Capsule
- Baker’s Cyst Indicative of too much swelling
Posterior Knee
The PCL receives posterior support from of two structures; _ ? _ and _ ? _ , which both resist _ ? _ .
Knee - Anatomy & Biomechanics
- The PCL receives posterior support from of two structures; a thick posterior capsule and the oblique popliteal ligament, which resist
- Both structures resist hyperextension
Posterior Knee
Posterior lateral corner support is provided by = ?
4
Knee - Anatomy & Biomechanics
Posterior lateral corner support is provided by:
- Lateral Collateral Ligament (Green)
- Popliteus (Red)
- Arcuate Ligament (Yellow)
- Biceps Femoris
Menisci
- Provides = ?
- Which meniscus moves more = ?
Knee - Anatomy & Biomechanics
Menisci:
- Provides stability, cushion, nutrition, and proprioception to the knee.
- Lateral meniscus moves more than medial
Attaches to and Dynamized by:
Patello-meniscal Retinaculum aka Quads
Semimenbranosis/Biceps Femoris/Popliteus
Capsule
MCL/Mensicofemoral /Mensicotibial Ligaments
Vascularity is Worse in the Middle
Outside 10-30% = Vascularized
Inside = Synovial Fluid (movement important for healing)
Menisci
Attaches to, and dynamized (controlled throughout movement) by a host of structures, which include = ?
Knee - Anatomy & Biomechanics
Menisci:
- Attaches to and Dynamized by:
- Patello-meniscal Retinaculum aka Quads
- Semimenbranosis
- Biceps Femoris
- Popliteus
- Capsule
- MCL / Mensicofemoral & Mensicotibial Ligaments
Menisci
Vascularity is worse in the _ ?_ .
Knee - Anatomy & Biomechanics
Menisci:
- Vascularity is worse in the middle
- Outside 10-30% = Vascularized
- Inside = Synovial Fluid (movement important for healing)
Lower Extremity Roles
- Trunk = ?
- Hip = ?
- Knee = ?
- Ankle/Foot = ?
Knee - Anatomy & Biomechanics
Lower Extremity Roles:
- Trunk = Stability
- Hip = Force Generation
- Knee = Force Generation
- Ankle/Foot = Force Transmission
What muscles crossing the knee joint = ?
Knee - Anatomy & Biomechanics
Muscles Crossing the Knee:
- Lateral = Iliotibial Band
- Anterior = Quadriceps
- Posterior = Hamstrings, Gastrocnemius
- Medial = Gracilis, Sartorius and Adductor Magnus ( Doesn’t Cross Joint )
Muscles Crossing the Knee
The stability we do have at this joint comes laterally from the _ ? _ , anteriorly from the _ ? _ , posteriorly from the _ ? _ and _ ? _ , and medially from the _ ? _ , and _ ? _ muscles.
Knee - Anatomy & Biomechanics
Muscles Crossing the Knee:
- The stability we do have at this joint comes
- laterally from the IT-band ,
- anteriorly from the quads ,
- posteriorly from the hamstrings and gastrocs, and
- medially from the adductors and pes anserine muscles .
Innervation of the Knee
Posterior knee is innervated by = ?
alot
Knee - Anatomy & Biomechanics
Innervation of the Knee - Posterior:
- Sciatic Nerve, Mixed
(a) Sacral Plexus (L4-S4)
(b) Common Fibular Nerve, Mixed
- Superficial Fibular Nerve, Mixed = Muscles of the Lateral Leg
- Deep Fibular Nerve, Mixed = Muscles of the Anterior Leg & Dorsum of Foot
(c) Tibial Nerve, Mixed = Muscles of the Posterior Leg & Plantar Foot
(d) Sural Nerve, Sensory
Innervation of the Knee
The sciatic nerve, arising from the sacral plexus from roots _ ? _ , it exits the pelvis and runs down the posterior leg nestled safely between its bodyguard, the hamstrings.
Knee - Anatomy & Biomechanics
The sciatic nerve, arising from the sacral plexus from roots L4-S4 , it exits the pelvis and runs down the posterior leg nestled safely between its bodyguard, the hamstrings.
Innervation of the Knee
At the top of the popliteal fossa, the sciatic nerve splits into the _ ? _ and _ ? _ nerves.
Knee - Anatomy & Biomechanics
- At the top of the popliteal fossa, the sciatic nerve splits into the
(1) Tibial Nerve:
(2) Common Fibular Nerve:
- Supplies the lateral portion of the knee as it crosses the joint, and then it travels anteriorly, wrapping vulnerably around the fibular head X to then split into a superficial branch that supplies the lateral muscles of the leg, like the peroneals,
Innervation of the Knee
Common fibular nerve further divides into = ?
Knee - Anatomy & Biomechanics
- Common Fibular Nerve: Supplies the lateral portion of the knee as it crosses the joint, and then it travels anteriorly, wrapping vulnerably around the fibular head.
(1) Superficial Fibular Nerve =
Muscles of the lateral leg
(2) Deep Fibular Nerve = Muscles of the anterior leg & dorsum of foot
Innervation of the Knee
Anterior knee is innervated by = ?
Knee - Anatomy & Biomechanics
Innervation of the Knee - Anterior:
(a) Femoral, Mixed
- Lumbar Plexus (L2-L4)
- Muscles of the Anterior Thigh
- Sensation of the Anterior Leg
- - Anterior Cutaneous, Proximal Sensory
- - Saphenous Nerve, Distal Sensory
(b) Obturator, Mixed
- Lumbar Plexus (L2-L4)
- Muscles of the Medial Thigh
- Sensation of the Medial Thigh
(c) Lateral Cutaneous, Sensory
- Lumbar Plexus (L2-L3)
- Sensation of the Lateral Thigh
Innervation of the Knee
True or False:
Anteriorly (knee), we deal with nerves from higher up the spine at the lumbar plexus.
Knee - Anatomy & Biomechanics
True
- Anteriorly (knee), we deal with nerves from higher up the spine at the lumbar plexus.
Innervation of the Knee
The largest nerve of the lumbar plexus is the _ ? _ .
Knee - Anatomy & Biomechanics
- The largest nerve of the lumbar plexus is the femoral nerve, which descends anteriorly to provide muscular innervation to the anterior thigh, like to the sartorius and quads, while also sending off sensory branches called the anterior cutaneous and saphenous nerves.
- These provide anteromedial sensation down the entire leg, with the anterior cutaneous being proximal to the knee, and the saphenous nerve being distal.
Innervation of the Knee
On the medial side, the _ ? _ is another mixed nerve that provides a lot of muscular innervation to all our adductors, and it also provides sensory information from the medial leg.
Knee - Anatomy & Biomechanics
On the medial side, the obturator nerve is another mixed nerve that provides a lot of muscular innervation to all our adductors, and it also provides sensory information from the medial leg.
