Chapter 20: The Knee and Related Structures

Ligaments

• ACL– Prevents anterior tibial translation

• PCL – prevents posterior tibial translation

• Medial Collateral– Prevents valgus

• Lateral Collateral– Prevents varus

Patella

• Patella – aids knee during extension, providing

a mechanical advantage– Protects patellar tendon against

friction

Assessing the Knee Joint• Determining the mechanism of injury is

critical• History- Current Injury

– Past history– Mechanism- what position was your body in?– Did the knee collapse?– Did you hear or feel anything?– Could you move your knee immediately after

injury or was it locked?– Did swelling occur?– Where was the pain

• History - Recurrent or Chronic Injury– What is your major complaint?– When did you first notice the condition?– Is there recurrent swelling?– Does the knee lock or catch?– Is there severe pain?– Grinding or grating?– Does it ever feel like giving way?– What does it feel like when ascending and

descending stairs?– What past treatment have you undergone?

• Observation– Walking, half squatting, going up and

down stairs– Swelling, ecchymosis,– Leg alignment

• Genu valgum and genu varum• Hyperextension and hyperflexion• Patella alta and baja

Patella Baja and Alta

– Knee Symmetry or Asymmetry• Do the knees look symmetrical? Is there

obvious swelling? Atrophy?

– Leg Length Discrepancy• Anatomical or functional• Anatomical differences

– A true difference in bone length

• Functional differences – caused by pelvic rotations or mal-alignment of

the spine

Obvious swelling

• Types of, and Palpation of Swelling– Intra vs. extracapsular swelling

• Intracapsular may be referred to as joint effusion

• Ballotable patella - sign of joint effusion

– Extracapsular swelling tends to localize over the injured structure • May ultimately migrate down to foot and

ankle

Q Angle

• Lines which bisect the patella relative to the ASIS and the tibial tubercle

• Normal angle is 10 degrees for males and 15 degrees for females

Q-angleQ-angle

Knee Injuries

Knee Sprains - MCL

Knee Sprains - MCL

• Mechanism of Injury– Valgus Force– Pivoting

Knee Sprains - LCL

Knee Sprains - LCL

• Mechanism of Injury– Varus Force

Knee Sprains - ACL

Knee Sprains - ACL• Mechanism of Injury

Cutting Pivoting

Knee Sprains - ACL• Mechanism of Injury

• Anterior tibial

translation on a fixed

femur.

Knee Sprains - ACL• Mechanism of Injury

Valgus Varus

Knee Sprains - PCL

Knee Sprains - PCL• Mechanism of Injury

Hyperextension

Knee Sprains - PCL

• Posterior tibial translation on a fixedfemur.

Injury Videoshttp://www.youtube.com/watch?v=A9-KkUH8yt8

http://www.youtube.com/watch?v=-pKaBW99GgY

http://www.youtube.com/watch?v=j_Mdm4v-ty8

The MOI of an MCL injury is:

1 2 3 4 5 6

17% 17% 17%17%17%17%1. Valgus force2. Varus force3. Pivoting4. Hyperextension5. All of the above6. All but 2

The MOI of an LCL injury is:

1 2 3 4 5 6

17% 17% 17%17%17%17%1. Valgus force2. Varus force3. Pivoting4. Hyperextension5. All of the above6. All but 1

The ACL is most commonly injured by:

17%

17%

17%17%

17%

17%

1 2 3 4 5 6

1. Valgus force2. Varus force3. Hyperextension4. Pivoting5. All of the above6. All but 2

Meniscus • Function

– Shock Absorption– Centering Mechanism (stability)– Production of Synovial Fluid (joint

oil)

Meniscus Injuries• Usually occurs with a hyperflexion

or twist (pivot) while weight bearing

Meniscus Injuries

Meniscus Injuries

Meniscus Injuries• Signs & Symptoms

– Awkward Mechanism– “Shift” or “pop”– Deep knee pain– Loss of terminal ext. or flex.– Delayed swelling– Jointline tenderness

Meniscal injuries are caused by:

20%

20%

20%

20%

20%

1 2 3 4 5

1. Hyperextension2. Hyperflexion3. Pivoting4. All of the above5. None of the

above

Patello-femoral Disorders

Patello-femoral Disorders

• Chondromalacia– Softening of articular cartilage

• Patello-femoral pain syndrome– Pain/inflammaton under patella

• *Acute patellar dislocation• *Patellar tendinitis (jumpers knee)

– Quadriceps tendinitis

• *Osgood Schlatter’s– apophysitis

Why are patellar tracking problems Often lateral?

**Read about the differences inyour text!!!

Patello-femoral Disorders

• Dislocation/Subluxation

Patello-femoral Disorders

• Patellar tendonitis

Patello-femoral Disorders• Osgood Schlatter

Runner’s Knee

• Due to overuse– The IT Band rubsOver the lateralCondyle of the femur

• Results in tendinitis of the IT band

Pes Anserine Tendinitis

• Tendinitis/Bursitis of the distal insertion of the sartorius, gracilis, and semitendinosis

The difference between runner’s knee and Pes Anserine tendinitis is:

33%

33%

33%

1 2 3

1. Runner’s knee is lateral

2. Runner’s knee is uncommon

3. There is no difference