Knee Anatomy and Evaluation By Dr. Sue Shapiro

Osseous Structures Formed by the articulations of femur, tibia, and patella. They form 2 articulations Tibiofemoral joint Patellofemural joint These two articulation are not independent of each other but have a biomechanical relationship

Femur Anatomy Distal Aspect Posterior Aspect Condyles Epicondyles Articulate with patella and tibia. Posterior Aspect Epicondyles

Tibial Anatomy Tibial Plateus Anterior Portion Medial plateau Lateral plateau Anterior Portion Tibial tuberosity

Tibiofemoral & Femoral Joints Motion in 2 planes Flexion/Extension & IR/ER Motion of the tibia on the femur Femoral Rotation Flex/Ext above meniscus IR/ER below meniscus The Screw Home Mechanism Results in ER of the femur at terminal Ext.

Patellofemoral Joint The patella a triangular in both sagital and frontal plane The superior portion ins wider than it distal part 5 distinct facets super., infer., lateral, medial and odd

Osseous Abnormalities Genus Varus and Valgus Knock Knee - excessive valgus Bowleg - excessive varus Genus Recurvatum - excessive extension Shallow Trochlear Groove - redisposed to ACL problems Patella Abnormalities - camel sign

Osseous Abnormalities

Extra Articular Structures Extensor Mechanism Function to provide deceleration of the patellofemoral articulation at different points along flexion/extension motion. Lateral retinaculum- static stabilizer Vastus Lateralis & IT band - dynamic stabilizers Medial retinaculum- static stabilizer Vastus Medialis & Adductor Magnus- dynamic stabilizers

Extensor Mechanism Extensor Mechanism Function to provide deceleration of the patellofemoral articulation at different points Lateral retinaculum- static stabilizer Vastus Lateralis & IT band - dynamic stabilizers Medial retinaculum- static stabilizer Vastus Medialis & Adductor Magnus- dynamic stabilizers

Extensor Mechanism Superior of the patella is supported by the lateral and medial patellofemoral ligament, and inferior by the patello-tibial ligament

Q-Angle The relationship b/t line of pull of the quadriceps and the line of the tendon from the midpoint on the patella to its insertion on the tibial tuberosity. Normal ranges Male - 13 degrees Female - 18 degrees

Patella Plica A fold in the synovial lining of the knee Signs Aggravated by quadriceps exercise + Moviegoer’s sign Pop or snap as the knee is flexed and extended Point tenderness at medial and lateral retinacular regions

Joint Capsule Characteritics Medial, lateral and anterior aspects arises superior to the femoral condyles and fixates distal to the tibial condyle Posteriorly the capsule attaches to the posterior margins of the femoral condyles above the Jt. Line & inferiorly, to the posterior tibial condyle Strength of the capsule is reinforced by the collateral lig. Medially & laterally, the retinaculum medially & laterally, the oblique popliteal lig. and the patella tendon Capsular attachment of the menisci along the peipheral border of the tibia thus hulding the minisci to the articular surface - CORONARY LIGAMENT

Collateral Ligament Medial Collateral Lig. Lateral Collateral Lig. Deep & Superficial Layers Primary Function is to protect the knee against valgus Lateral Collateral Lig. No attachment to the capsule or meniscus Primary restrain against varus forces

Medial Knee Anatomy Medial Knee muscle Insertion Semimembranosus Medial Gastroc VMO Adductor Magnus Pes Anerine Group

Lateral Knee Anatomy Posteriorlateral Structures Middle Third Arcuate Lig. Complex Popliteous Muscle Lateral Grastroc Head Arcuate Lig. Posterior third of the capsular lig. Middle Third LCL Mid-lat capsular lig Bicep Femoris Muscle

Lateral Knee Anatomy Anteriorlateral Aspect Posterior Compartment Joint Line Lateral patellar restrainsts Ilitibial Tract & insertion Fibular head Common peroneal nerve Posterior Compartment Bicep Femoris Semimmembranosis Medial & lateral head gastroc Popliteal fossa Popliteal pulse

Intra Articular Structures Menisci Functions Distributed WB load over a large surface area To increase stability Increase joint congruency by deepening the tibia plateau Limits abnormal movements

Menisci Peripheral Meniscus Medial Meniscus The outer perimeter is vascular & has the ability to heal itself if torn. Coronary ligament attach outer perimeter to tibial plateau Medial Meniscus Avascular & can not heal if torn Semimbranosus attaches to the posterior horn C-shaped & attaches to the MCL and medial capsule

Lateral Meniscus O-shaped Popliteus tendon attaches to the posterior horn & this causes pot. Translation during knee flexion

Meniscus Biomechanics Mechanism of Injury Total Excursion (ant/post) Medial - 6 mm Lateral - 12 mm Knee Extension Kaplan’s Lig. Pulls menisci anteriorly Knee Flexion Semimembranosus pulls medial menisci Popliteus pulls lateral menisci Mechanism of Injury Flexion/ Rotation Injury In flexed position (w/wt) trying to extend the post. Horns get trap and create a bucket handle tear which create pseudo-locking

Types of Menisci Most commonly torn in the posterior horn Unusual for a anterior meniscal tear Second most common in middle Names of meniscus tear Medial- Longitudinal, complex, horizontal. Cleavage Lateral - Radial, longitudinal, bucket-handle

Cruciate Ligaments Anterior Cruciate Lig. Anatomy of ACL Three Bundles Anteromedial Intermediate Posterolateral Special Teest Anterior Drawer Lachman’s Test Functions of ACL anterior displacement of tibia to the femur Stabilizer of rotation

Anterior Cruciate Lig Factors affecting ACL rupture Ligament Restrains Equipment Design Technique Fitness Anatomy Intercodylar Notch Narrow Notch Quick Rotation (ER) Notchplasty Braces Prophylactic & Functional Ligament Restrains Anterior Stability Provides 89% of restraint to anterior displacement Secondary restraints - 15% Stress on ACL Greatest stress (30-0 deg,)

Anterior Cruciate Lig Signs and Symptoms Pivot: deceleration + valgus stress + ER tibia Hyperextension Direct contact 80-90% hear/feel “pop/click” Perception of the knee going out of place Accumulation of effusion over 2-24 hours

Posterior Cruciate Lig. Anatomy Two bundles Posteromedial Anteromedial Stability Provides 95% of restraint to posterior displacement Function Prevents posterior displacement of the tibia on femur Mechanism of Injury Blow to proximal tibia, or fall on flexed knee with plantar flexion PCL Testing Recurvatum Sag Test Clancy’s Step Up Posterior Drawer

Bursas Intracapsular Extracapsular Suprapatellar Subpopliteal Semimembranosus Extracapsular Prepatellar Superficial infrapatellar Deep infrapatellar

Bursas Functions During motion of flexion and extension synovial fluid moves throughout the bursal recesses to lubricate the articular surface and the bursas compress compressing fluid in many directions. Give protection to articular surfaces at the sites of tendon attachment

Reflexes and Cutaneous Distribution Patellar reflex ( L3 - L4) Medial Hamstrings reflex (L5 - S1)

Reflexes and Cutaneous Distribution Nerves Tibial Nerve (L4-S3) Common Peroneal Nerve (L4-S2) Femoral Nerve (L2-L4) Saphenous Nerve (L3-L4)

Reflexes and Cutaneous Distribution Blood Supply Popliteal Artery Located in popliteal fossa