The Knee

From the Sports Medicine Perspective

Bony Anatomy

Femur

Patella

Tibia

Fibula

Bony Anatomy

Femur: Longest Bone in BodyTibia: WB bone of lower extremityFibula: Site of Muscle AttachmentPatella: 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

Menisci

Medial Meniscus

Lateral Meniscus

PCL

ACL

Knee Ligaments

Medial Collateral LigamentMCL

MCL

Thick Band of TissueTibia FemurResists 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 tissueFibula FemurResists Varus Forces

Varus

Inside to Outside Force

LCL resists this forceFRONTAL PLANE

Increased Valgus

Collateral Ligament Ruptures

Ligament Structures

Anterior Knee

Anterior Cruciate Ligament ACL

Composed of 3 bandsPrevents anterior

translation of tibiaStabilizes against

excessive rotationStabilizing 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 FemorisVastus LateralisVastus MedialisVastus Intermedius

Extend the Knee

Quadriceps

Rectus Femoris

2 Joint MuscleCrosses hip and knee

Flexes HipExtend the kneeConverges with rest

of quadriceps muscles at tibial tubercle

Hamstrings

Three MusclesSemimembranosusSemitendinosusBiceps Femoris

Common Origin the ischial tuberosity

Flex the Knee

Hamstrings

Popliteus

Popliteus

MCL Sprains

Valgus ForceTensile Mechanism

MCLFlexed 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 instabilityMild EffusionROM fullMild tenderness w/

palpation

MCL/LCL Injuries

GRADE II: Laxity w/ valgus or

varus stress (more with 30 degrees of flexion)

Decrease in ROMIncrease medial

(MCL) or lateral (LCL) pain

GRADE III:Complete ligament

ruptureComplete loss of

stabilityImmediate pain that

transitions into dull ache

Treatment

Based on severity of injury

RICEModify activityCrutchesExercises in sagittal

planeProgress to

functional exercise