Knee Conditions

Chapter 15

Anatomy

Large synovial joint

Two condylar articulationsMedial tibiofemoral jointLateral tibiofemoral joint

Gliding jointPatellofemoral joint

Bones

FemurMedial epicondyleLateral epicondyleLinea aspera

TibiaMedial tibial plateauLateral tibial plateau

Fibula

Tibiofemoral Joint

Modified hinge joint allowing some lateral and rotational motions to occur as well.

Lateral epicondyle is larger than medial.

Because of size difference there is a screwing home mechanism to bring the knee into full extension.

Menisci

Semilunar fibrocartilage (half moon shapes)Attach to the superior plateaus of the tibia.Absorption and dissipation of forceLubricationMedial meniscus is semicircular and attaches to the medial collateral ligamentLateral meniscus is almost a complete circle and attaches to the posterior cruciate ligament

Bursae

Suprapatellar bursa, lies between the femur and quadriceps femoris tendonSubpopliteal bursa, lies between the femur and the popliteal muscleSemimembranosus bursa, lies between the medial head of the gastrocnemius and the semimembranosus tendon.Prepatellar bursa, lies between the skin and the anterior surface of the patella

Bursae continued

Superficial infrapatellar bursa is located between the skin and the patellar tendon.

Deep infrapatellar bursa is located between the tibial tubercle and the infrapatellar tendon.

Ligaments

Anterior Cruciate Ligament (ACL), attaches anteriorly on the tibia, and to the posterior surface of the lateral femoral condyle.

Prevents: Anterior translation of the tibia on a fixed femur Posterior translation of the femur on a fixed tibia Internal and external rotation of the tibia on the

femur Hyperextension of the tibia

Ligaments continued

Posterior Cruciate Ligament (PCL), attaches posteriorly to the tibia, and to the anterior surface of the lateral medial condyle of the femur.

Prevents:Posterior displacement of the tibia on a

fixed femur.

Ligaments continued

Medial collateral ligament (MCL) connects from the medial condyle of the femur to the medial tibia through the medial meniscus.

Prevents:Medially directed shear forces (valgus)Rotational forces

Ligaments continued

Lateral collateral ligament (LCL) connects from the lateral condyle of the femur to the head of the fibula.

Prevents:Laterally directed shear forces (Varus)External rotation of the tibia

Ligaments continued

Arcuate-popliteal complex composed of the semimembranosus tendon and the popliteal ligament connects the lateral condyle of the femur to the head of the fibula.

Prevents: Anterior displacement of the tibia relative to the

femur. Hyperextension of the knee Hyperflexion of the knee

Patellofemoral joint

Triangular bone (Patella) rests between the femoral condyle to form the patellofemoral joint.Three distinct facetsIncreases angle of pull on the patellar tendonGlides between the femoral Trochlear groove

Patellofemoral joint cont.

Greatest compressive forces occur when the knee is in 30 deg. Of flexion.

Patellar positioning is maintained by:Lateral retinaculumMedial retinaculumMedial patellofemoral ligamentLateral patellofemoral ligament

Muscles of the Knee

Rectus femoris (ext)Vastus lateralis (ext)Vastus intermedius (ext)Vastus medialis (ext)Semitendinosis (flex)Semimembranosus (flx)

Biceps femoris (flex)

Sartorius (flex)

Gracilis (flex)

Popliteus (flex)

Gastrocnemius (flex)

Plantaris (flex)

Nerves

L4

L5

S1

S2

S3

Kinematics

Flexion primarily carried out by the hamstrings assisted by gastroc, popliteus, gracilis, and sartorius.

Secondary responsibility of these muscles is to rotate the tibia

Extension primarily carried out by the quadriceps group.

Contusions

Fat Pad Contusion

Peroneal Nerve Contusion

Bursitis

Prepatellar

Deep infrapatellar bursitis

Pes anserine bursitis

Tibial collateral bursitis

Ligamentous Injuries

Straight valgus

Straight varus

Straight anterior

Straight posterior

Anteromedial rotary

Anterolateral rotary

Posteromedial rotary

Posteroladeral rotary

Knee Dislocations

Meniscal Injuries

Longitudinal

Bucket-handle

Horizontal

Parrot-beak

Patellar and Related injuries

Patellofemoral stress syndrome

Chondromalacia Patellae

Patellar Instability and Dislocations

Patella Plica Syndrome

Patellar Tendinitis

Osgood-Schlatter Disease

Sinding-Larsen-Johansson’s Disease

Extensor Tendon Rupture

IT Band Friction Syndrome

Fractures

Avulsion

Epiphyseal and Apophyseal

Tibial Tubercle

Distal Femoral Epiphyseal

Stress Fractures

Chondral and Osteochondral Fractures

Osteochondritis Dissecans

Patellar Fractures