The Knee

From the Sports Medicine Perspective

Bony Anatomy Femur Patella Tibia Fibula

Bony Anatomy Femur: Longest Bone in Body Tibia: WB bone of lower extremity Fibula: Site of Muscle Attachment Patella: Sesamoid Bone A bone that develops within a tendon

Knee Skeletal Lateral Condyle Head of Fibula Femoral Groove Gerdy’s Tubercle Tibial Tuberosity Pes Anserine

Sagittal MRI View

Knee Connective Tissue

Knee Menisci

Menisci

Medial Meniscus Lateral Meniscus PCL ACL

Knee Ligaments

Medial Collateral Ligament MCL

MCL Thick Band of Tissue Tibia  Femur Resists Valgus Force

Valgus Outside to Inside Force MCL resists this force Occurs in FRONTAL PLANE

Lateral Collateral Ligament LCL

LCL Narrow cord like band of tissue Fibula  Femur Resists Varus Forces

Varus Inside to Outside Force LCL resists this force FRONTAL PLANE

Increased Valgus

Collateral Ligament Ruptures

Ligament Structures

Anterior Knee

Anterior Cruciate Ligament ACL Composed of 3 bands Prevents anterior translation of tibia Stabilizes against excessive rotation Stabilizing Ligament

Healthy ACL

Torn ACL

Knee Posterior

Posterior Cruciate Ligament PCL Stabilizes the posterior aspect of knee Prevents hyperextension

Cadaver Knee

Quadriceps Anterior Thigh Musculature Four Muscles: Rectus Femoris Vastus Lateralis Vastus Medialis Vastus Intermedius Extend the Knee

Quadriceps

Rectus Femoris 2 Joint Muscle Crosses hip and knee Flexes Hip Extend the knee Converges with rest of quadriceps muscles at tibial tubercle

Hamstrings Three Muscles Semimembranosus Semitendinosus Biceps Femoris Common Origin the ischial tuberosity Flex the Knee

Hamstrings

Popliteus

MCL Sprains Valgus Force Tensile Mechanism  MCL  Flexed knee more vulnerable (open pack position = less stable)

MCL Injuries Direct trauma in frontal plane injures MCL Combination of rotation can result in ACL and meniscus tears

MCL/LCL Injuries GRADE I: No instability Mild Effusion ROM full Mild tenderness w/ palpation

MCL/LCL Injuries GRADE II: Laxity w/ valgus or varus stress (more with 30 degrees of flexion) Decrease in ROM Increase medial (MCL) or lateral (LCL) pain GRADE III: Complete ligament rupture Complete loss of stability Immediate pain that transitions into dull ache

Treatment Based on severity of injury RICE Modify activity Crutches Exercises in sagittal plane Progress to functional exercise