The Knee

What is the knee joint?

A hinge joint with 1 degree of freedom

What are the osteokinematic motions of the knee joint?

Flexion and extension (some rotation with each)

What are the arthrokinematic movements of the knee joint?

• Includes roll, spin, and glide

What is the open-pack position of the knee joint?

• 25 dg flexion for tibiofemoral- ideal for mobilization and assessing joint play

• 10-20 degrees for patellofemoral

What is the closed-pack position of the knee joint?

Full extension

What is the patellofemoral joint?

• The smooth posterior surface glides over the patellar surface of the femur

• Functions to improve the mechanical advantage of the quadriceps by lengthening their moment arm and protects the knee joint

• Mechanical dysfunction is common at this site

What is the Q-angle?

• The angle between the femur and the tibia (looking anteriorly and vertically)

• The intersection of the line from the ASIS to the middle patella and the line from the tibial tuberosity to the middle patella

• Is usually 13-19 dgs (often larger in women than men)

• Abnormality can result in patellofemoral syndrome

What are the two groups of ligaments at the knee joint? What do they do?

• The collateral and cruciate ligament groups

• They provide support along with muscles since the bone does NOT provide stability

What is the anterior cruciate ligament?

• Attaches to the anterior, medial surface of the tibia in the intercondylar area and posterior aspect of the lateral femoral condyle

What does the ACL prevent?

Prevents the tibia from displacing anteriorly on the femur (or the femur displacing posteriorly on the tibia)

What is the posterior cruciate ligament?

• Connects at the posterior tibia (intercondylar fossa) and the anterior aspect of femur on the medial epicondyle

• Becomes tight with flexion of the knee

• Less commonly injured than the ACL

What does the PCL prevent?

Prevents the tibia from displacing posteriorly on the femur (or femur anteriorly on the tibia)

What is the medial collateral ligament?

• Attaches to the medial condyles of the tibia and the femur

• Has fibers attaching to the medial meniscus

• Provides stability in the frontal plane (side to side)

• Tight during extension

• Damaged with valgus forces

What lateral collateral ligament?

• Attaches at the lateral condyle of the femur and the head of the fibula

• Damaged with varus forces

• Provides stability in the frontal plane (side to side)

• Tight during extension

What are menisci?

• Absorb shock

• Deepen the concavity of the articular surface of the tibia

Which meniscus is torn more often?

The medial

Which meniscus is thicker?

The lateral

What is the normal end-feel for knee flexion?

• Soft end feel due to contact between the thigh and the leg

• Assessed in supine

What is the normal end-feel for knee extension?

• Firm end feel due to tension in the joint capsule and ligaments

• Assessed in supine

What is the popliteal space/fossa?

The area behind the knee containing the tibial nerve, common peroneal nerve, popliteal artery and vein

What is the pes anserine?

• Conjoined tendon of the semitendinosus, gracilis, and sartorius on the proximal medial tibia

• A common site for bursitis

What muscle are in the quadriceps muscle group?

• Rectus femoris

• Vastus lateralis

• Vastus medialis

• Vastus Intermedius

What muscles are in the hamstring muscle group?

• Biceps femoris

• Semitendinosus

• Semimembranosus

What is genu valgum/valgus?

• Inward angulation of the knee

• The direction the MCL is injured

What is genu varum/varus/vargum?

• Outward angulation of the knee

• The direction the LCL is injured

What is genu recurvatum?

• Backward angulation of the knee

• This is the direction the ACL is injured

What are the arthrokinematics of open-chain knee extension?

The concave tibial plateau glides anteriorly on the convex femoral condyles and then spins/rotates laterally

What are the arthrokinematics of open-chain knee flexion?

The concave tibial plateau spins/rotates medially on the convex femoral condyles and then glides posteriorly

What are the arthrokinematics of closed-chain knee extension?

• The convex femoral condyles glide posteriorly as it rolls anteriorly into extension and then medially rotates on the concave tibia

• Due to the larger articular surface of the medial femoral condyle, it continues to glide posteriorly during the last few degrees

• During weight bearing, the femur spins (rotates medially) on the tibia

What are the arthrokinematics of closed chain knee flexion?

The convex femoral condyles laterally rotate on the concave tibia to “unlock” the knee, they then glide anteriorly as they roll posteriorly into flexion

What is the capsular pattern of the tibiofemoral and patellofemoral joint?

More limitation in flexion than extension

What pathology is most likely to increase the Q-angle in a patient?

Osteoarthritis of the knee

What is the MOST likely problem if a patient has symptoms of locking of the knee, pain, knee gives way, and brief inability to bear weight?

Meniscal tear