Anatomy and Injuries of the Knee

Adapted from Connie RauserSabino Sports Medicine

Anatomy-Bones

Bones◦Femur

Medial/lateral femoral condyles articulate w/ tibia◦Tibia

Tibial plateau is flat-articulates w/ femoral condyles

◦Fibula Articulates w/ tibia

◦Patella Sesamoid bone protects anterior joint Enclosed in quadriceps/patellar tendon

Anatomy-Joints

Joints◦Tibiofemoral

Hinge joint with synovial lining ◦diarthrodial

◦Patellofemoral◦Superior Tibiofibular

Anatomy-Meniscus

Meniscus◦Medial and lateral◦Fibrocartilaginous disks

Thicker on outside than inside (poor blood supply)◦Lie on top of tibial plateau◦Increase stability◦Make condyles fit better◦Shock absorbers

Anatomy-Ligaments

ACL-anterior cruciate ligament◦Runs from anterior tibia to posterior femur◦Prevents anterior displacement of tibia on fixed

femur◦Prevents femur from moving posterior during

weight bearing◦Stabilizes tibia against excessive internal

rotation

Ligaments

PCL-posterior cruciate ligament◦Runs from posterior tibia to anterior femur◦Prevents posterior translation of tibia on fixed

femur◦Prevents femur from moving anterior during

weight bearing

Both ACL and PCL “cross” or wrap around each other—taut when in extension and looser when in flexion

Ligaments

MCL-medial collateral ligament◦Attaches on the medial femoral epicondyle &

anteromedial tibia◦Thickened portion of joint capsule◦Two parts-superficial and deep

Deep portion attaches to medial meniscus◦Stabilizes against valgus stress applied to

lateral aspect of joint capsule

Ligaments

LCL-lateral collateral ligament◦Attaches to lateral femoral epicondyle and

head of fibula◦Stabilizes against varus stress when force is

applied to medial aspect of joint

Both the MCL and LCL are tightest during full extension of knee and relaxed during flexion

Ligaments

Muscles

Quadriceps◦ Rectus femoris, vastus lateralis, vastus medialis, vastus

intermedius Knee extension, hip flexion

Hamstrings◦ Biceps femoris, semimembranosus, semitendinosus

Knee flexion, hip extension

Muscles

Gracilis◦Knee flexion, hip adduction

Sartorius◦Knee flexion, hip flexion, hip external rotation

Popliteus◦Knee flexion

Gastrocnemius◦Knee flexion

Muscles

Plantaris◦Knee flexion

Pes anserine◦Goose’s foot◦Knee flexion, some internal rotation

Gracilis, sartorius, semitendinosusIliotibial BandApart of the tensor fascia latae

◦Thick band on lateral aspect of thigh Attaches at Gerdy’s tubercle on the lateral aspect of

tibia

Anatomy of Knee

Preventing knee injuries

Conditioning◦Strength, flexibility, cardiovascular and

muscular endurance Hamstring strength 60% of quad strength

Rehabilitation◦Strengthen all muscles around knee joint

Shoes◦proper type for surface◦Length of cleats◦Turf vs grass

Preventing knee injuries Knee braces

◦ Functional vs. prophylactic Functional—used to provide support to an unstable

knee Usually custom fitted to some degree Uses hinges and supports to control excessive

rotational stress and tibial translation

Prophylactic-worn on lateral aspect knee to protect MCL.

Usefulness questioned—does it cause more injuries?

Muscle Strains

MOI: Sudden contraction of muscle or muscle being

overstretchedS/S:

-Stretching/pulling sensation-Pain with active movement and passive

stretching

Tx: RICE, modalities, alternative training exercises to allow muscle to rest

ACL rupture

MOI: ◦fixed foot and external rotation of femur◦knee in valgus position ◦hyperextension

S/S: ◦“pop”, ◦knee gives out ◦instability of knee joint ◦swelling within knee joint—hemarthrosis ◦intense pain initially but still able to walk◦“+” Lachman’s test◦“+” anterior drawer test

MOI

MOI

Hyperextension

ACL rupture

Inside the knee joint

The ACL intact The ACL torn

ACL Rupture

Tx: RICE, knee immobilizer, crutches, Physician referral

Requires surgical reconstruction◦Timing of surgery decided by athlete, parents,

doctor◦Grafts used are patellar tendon, hamstring

tendon, cadaver graft, allograft◦3-5 weeks in brace, 6-9 months return to

activity

ACL Rupture

Knee post-ACL tear

Test for SwellingBallotable Patella Test

Stress tests

Lachman’s test

Stress tests

Modified Lachman’s

Stress tests

Anterior Drawer test

PCL Rupture

MOI: ◦hyperflexion◦falling on bent knee with foot plantar flexed◦Hit on fixed anterior tibia

S/S: ◦“pop” at the back of knee◦Pt. Tender and swelling in popliteal fossa◦+ posterior sag test,+ posterior drawer test

PCL rupture

Tx:◦RICE◦Immobilization◦Crutches◦Physician referral◦6-8 weeks rest/rehab◦If surgery is elected, 6 weeks immobilization

PCL rupture

Stress tests

Posterior sag

Stress tests

Sunrise or posterior sag

MCL Sprain

MOI: ◦Blow to the lateral side of knee (valgus stress)◦External rotation of tibia

MOI

MCL sprain

2nd degree??

MCL sprain

S/S:1st degree

◦Pt. Tender over MCL, stable but pain with valgus stress, mild joint effusion, mild joint stiffness, full ROM

2nd degree◦Partial tearing-superficial portion, Pt. Tender over

MCL, some instability with valgus stress but solid endpoint, moderate joint effusion, joint stiffness, limited ROM, unable to fully extend knee joint

MCL Sprain

S/S:3rd degree

◦Complete tear—superficial and deep portions◦Pt. Tender over MCL◦Moderate to severe effusion◦Severe pain◦Loss of motion due to pain, effusion, muscle

guarding◦“+” valgus stress in 0 and 30 degrees, no

endpoint

Stress tests for MCL

Valgus stress test @ 0 Valgus stress @ 30

MCL Sprain

Tx:RICECrutchesKnee immobilizer/brace

◦1st degree 1-2 weeks◦2nd degree 2-4 weeks◦3rd degree 4-6 weeks

Physician referral for 2nd degree or greater

Complications

The terrible triad or unhappy triad◦Torn ACL◦Torn MCL◦Torn Medial meniscus

LCL sprain

MOI: ◦ Varus force to medial aspect of knee ◦ internal rotation of tibia

S/S: ◦ Pt. Tender over LCL, ◦ pain, ◦ swelling, ◦ loss of motion, ◦ “+” varus stress at 30 degrees—solid endpoint with 1st

degree, less stability but solid endpoint with 2nd degree, no endpoint with 3rd degree

◦ if “+” varus stress at 0 degrees flexion suspect ACL or PCL injury as well

LCL sprain

Tx:◦RICE◦Crutches◦Knee immobilizer◦Physician referral with 2nd or 3rd degree

Meniscus tear

Medial: more often torn than later due to attachment to MCL

Lateral: doesn’t attach to joint capsule making it more mobile, less prone to injury

MOI:◦Weight bearing with rotational force while

extending or flexing the knee

Meniscus tear

S/S: ◦Effusion w/in 48-72 hours◦Pt. Tender over joint line◦Loss of motion◦“locking”◦Giving out◦Pain with deep knee flexion--squatting

Meniscus tear

Types of meniscus tears

Meniscus Tears Special Test

McMurray TestPositive Sign: Pain and/or clicking

Meniscus tears

Tx: RICECrutches if necessaryPhysician referralIf knee is “locked” by displaced meniscus,

go to ERArthroscopic surgery to fix

Injuries to the Patella

DislocationSubluxationFractureChondromalaciaPatellar tendonitisPatella Femoral Pain Syndrome

Patella Dislocation

MOI: ◦ Foot planted, deceleration, and cutting in

opposite direction from the weight bearing foot◦Thigh rotates internally while leg rotates

externally◦Strong forceful contraction of quads (vastus

lateralis)

Dislocation

S/S: loss of motion/function at the kneePainSwellingDeformityPt. Tender over medial aspect of knee joint

dislocation

dislocation

Dislocation

Tx: immobilize in position you find itIceER visitAfter reduction, immobilize in extension

about 4 weeks—use crutchesStrengthen muscles of knee, thigh and hip

Patella Subluxation

MOI: same as for the dislocationS/S:

◦same as for the dislocation except there will be no deformity

◦Pt. Tender over the medial knee joint◦Pain with movement

TX: ◦RICE◦Knee Immobilizer and crutches◦Physician referral

Patella fracture

MOI: ◦direct impact or trauma to patella◦Indirect trauma in which a severe pull of the

patellar tendon occurs against the femur when the knee if semi-flexed

S/S: ◦hemorrhage which results in significant swelling ◦pain ◦Pt. Tender over Patella◦extreme pain with weight bearing/movement

Patella Fracture

Another x-ray

Patella Fracture

Tx: RICEImmobilizeCrutchesERPossible surgery depending on type of

fracture

Chondromalacia

Softening and deterioration of the articular cartilage on the posterior side of the patella

Chondro

MOI: ◦related to abnormal movement of the patella

within the femoral groove as the knee flexes and extends

◦Lateral tracking patella as quads contract usually associated with weak quads (VMO) or in females a wider pelvis

Chondro

S/S: ◦Pain on the anterior aspect of the knee (behind

the patella) while walking, running, ascending or descending stairs, sqatting or sitting with knees flexed for a long period of time

◦Pain with compression of patella in femoral groove

Chondro

Tx: ◦remove from activities that cause the pain◦Strenghtening exercises for the quads,

especially the VMO◦Knee sleeve with patellar support◦Ice, heat◦Surgery to smooth the posterior side of patella

Osteochondritis Dissecans of Knee

Patellar tendonitis

Also called “jumper’s knee”MOI:

◦excessive running, jumping or kicking causing extreme tension of the knee extensor muscle complex

S/S: ◦Pain at the patellar tendon◦Pt. Tender over the distal pole of patella◦Pain increases with activity◦Thickening of tendon ◦crepitus

Patellar tendonitis

TX: ◦Rest◦Ice ◦Heat◦Ultrasound◦Cross-friction massage◦NSAIDS◦Patellar tendon strap/taping◦Modify activity

Patellafemoral Pain Syndrome

MOI: Overuse and Overload and we just don’t know…Signs and Symptoms:

◦Dull achy pain on or around anterior knee ◦ Pain with walking up or down stairs◦Pain with descending inclines◦Mild Swelling is possible

Tx:◦RICE◦Strengthening and stretching exercises to help

support the tendon◦Active Rest (biking, swimming)

Osgood-Schlatter’s Disease

Condition common in adolescent kneeMOI:

◦Repeated pull of patellar tendon at tibial tuberosity apophysis due to excessive running, jumping, kicking, etc.

S/S: ◦pain and Pt. Tender at the patellar tendon

attachment on tibial tuberosity◦Excessive bony formation over tubersity as

tendon continues to pull at the apophysis

Osgood Schlatter’s

S/S: ◦usually resolves itself when the athlete reaches

18-19 years of age◦Enlarged tibial tuberosity remains

Tx: ◦Modify activity◦Ice◦Tape/patellar tendon strap◦Padding◦Strengthening of quads and hamstrings

Iliotibial Band Friction Syndrome

MOI: ◦Overuse injury that occurs in runners or cyclists

attributed to the malalignment and structural asymmetries of the foot and lower leg

◦Irritation develops over lateral femoral epicondyle or at the band’s insertion at Gerdy’s tubercle on the lateral side of the tibia

ITBS

S/S: ◦Pt. Tender over the lateral femoral epicondyle◦Swelling◦Increased pain with activity especially distance

running and starts and stops and change of direction

ITBS

Tx: Stretching the ITBIce pack/massageTransverse friction massage ITBModify activityCorrect foot/lower leg malalignment

Bursitis

Can be acute, chronic, or recurrentNumerous bursae involved but most

commonly injured are the prepatellar or the deep infrapatellar

Bursitis

MOI: ◦falling directly on knee◦Continuous kneeling ◦Overuse of patellar tendon

Bursitis

S/S: ◦Localized swelling that is similar to a water

balloon and is outside the knee joint◦Pain especially with pressure

Bursitis

Bursitis

Bursitis

Tx: ◦Rest ◦Ice ◦Compression ◦NSAIDS◦Padding for protection when returning to

activity