Anatomy and Injuries of the Knee

John Hardin

SPHS 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, semitendinosus

• Iliotibial Band– Thick band on lateral aspect of thigh

• Attaches at Gerdy’s tubercle on the lateral aspect of tibia

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?

ACL rupture

• Mxn: – 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

MXN

MXN

• 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

Stress tests

• Lachman’s test

Stress tests

• Modified Lachman’s

Stress tests

• Anterior Drawer test

PCL Rupture

• Mxn: – hyperflexion– falling on bent knee with foot plantar flexed– Hit on fixed anterior tibia

• S/S: – “pop” at the back of knee– POT and swelling in popliteal fossa– + posterior sag test, +sunrise 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

Strest tests

• Sunrise or posterior sag

MCL Sprain

• Mxn: – Blow to the lateral side of knee (valgus stress)– External rotation of tibia

Mxn

MCL sprain

• 2nd degree??

MCL sprain

• S/S:• 1st degree

– POT over MCL, stable but pain with valgus stress, mild joint effusion, mild joint stiffness, full ROM

• 2nd degree– Partial tearing-superficial portion, POT 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– POT 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:

• RICE

• Crutches

• Knee 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

• Mxn: – Varus force to medial aspect of knee – internal rotation of tibia

• S/S: – POT 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

• Mxn:– Weight bearing with rotational force while

extending or flexing the knee

Meniscus tear

• S/S: – Effusion w/in 48-72 hours– POT over joint line– Loss of motion– “locking”– Giving out– Pain with deep knee flexion--squatting

Meniscus tear

• Types of meniscus tears

Meniscus tears

• Tx:

• RICE

• Crutches if necessary

• Physician referral

• If knee is “locked” by displaced meniscus, go to ER

• Arthroscopic surgery to fix

Injuries to the Patella

• Dislocation

• Subluxation

• Fracture

• Chondromalacia

• Patellar tendonitis

Patella Dislocation

• Mxn: – 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 knee

• Pain

• Swelling

• Deformity

• POT over medial aspect of knee joint

dislocation

dislocation

Dislocation

• Tx:

• immobilize in position you find it

• Ice

• ER visit

• After reduction, immobilize in extension about 4 weeks—use crutches

• Strengthen muscles of knee, thigh and hip

Patella Subluxation

• Mxn: same as for the dislocation• S/S:

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

– POT over the medial knee joint– Pain with movement

• TX: – RICE– Knee Immobilizer and crutches– Physician referral

Patella fracture

• Mxn: – 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 – POT over Patella– extreme pain with weight bearing/movement

Patella Fracture

Another x-ray

Patella Fracture

• Tx:

• RICE

• Immobilize

• Crutches

• ER

• Possible surgery depending on type of fracture

Chondromalacia

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

Chondro

• Mxn: – 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

Patellar tendonitis

• Also called “jumper’s knee”• Mxn:

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

• S/S: – Pain at the patellar tendon– POT 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

Osgood-Schlatter’s Disease

• Condition common in adolescent knee• Mxn:

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

• S/S: – pain and POT 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

• Mxn: – 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: – POT 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 ITB

• Ice pack/massage

• Transverse friction massage ITB

• Modify activity

• Correct foot/lower leg malalignment

Bursitis

• Can be acute, chronic, or recurrent

• Numerous bursae involved but most commonly injured are the prepatellar or the deep infrapatellar

Bursitis

• Mxn: – 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