Examination of the Acute Knee Injury

Differential Diagnosis

Most Common

1. Medial Meniscal Tear

2. Medial Collateral Ligament (MCL) Sprain

3. Anterior Cruciate Ligament (ACL) Tear

4. Articular Cartilage Injury

5. Posterior Cruciate Ligament (PCL) Strain or Tear

6. Patellar Dislocation

Some Miscellaneous Less Common Injuries:

1. Patellar Tendon Rupture

2. Acute Patellofemoral Joint Injury

3. Lateral Collateral Ligmant Sprain (LCL)

4. Coronary Ligament Sprain

5. Bursal Hematoma / Bursitis

6. Acute Fat Pad Impingement

7. Low Quadriceps Hematoma

8. Avulsion of Biceps Femoris Tendon

9. Dislocated Superior Tibiofibular Joint

Can't Miss Diagnoses

1. Avulsion Fractures

2. Osteochondritis Dissecans

3. Reflex Sympathetic Dystrophy

4. Fractures of the Tibial Plateau

History

• Precise mechanism of injury

• Symptoms: pain, giving way

• Swelling: time of onset and degree

• Popping / snapping / tearing : suggest ACL injury

• Significant past medical history

• Social History: activity / occupation

Examination

Always remember to examine the joint above (hip) and below (ankle)

Inspection

1. Scars or stretch marks

2. Wasting of muscles: Especially Vastis Medialis

3. Deformity of knee

4. Weight Bearing

Palpation

1. Patella

2. Palpate medial collateral ligament with knee at 90degrees of flexion

3. Palpate lateral collateral ligament with knee in figure-of-four position

4. Palpate at suprapatellar pouche for bogginess

5. Palpate joint space noting any tenderness

6. Palpate popliteal space for swelling or cysts

7. Palpate Joint Lines (medial and lateral)

Motion

Note that range of movement is measured determined actively first, if there is a deficiency, move on to passive range of motion. Any deficits should be measured with a goniometer. Note should be made of discrepence between active and passive movement.

Note should be made of any evidence of locking.

Valgus Stress to test the MCL, this is done in full extension and in 30 degrees of flexion.

Varus Stress to test the LCL, also done in full extension and in 30 degrees of flexion.

Muscles

Measurement of muscle strength using the Oxford (MRC) Scale.

1. Flexion

2. Extension

NeuroVascular

1. Check and Grade reflexes

2. Check Pulses

3. Sensation

Special Tests for Effusions

1. Bulge Sign or the varientWipe Test

2. Ballottment test for a floating patella

Special Tests for Meniscal Pathology

1. McMurray Test (note that this test cannot be performed if a large effusion is present).

2. Steinman Test part I and II

3. Helfet Sign

4. Apley compression/distraction test

5. Anderson Test

6. The Sign del Salto also known as the Finocchietto Jump Sign

7. Duck Waddle Test

Note that the accuracy of the McMurray, Steinman, and Apley tests is dependant upon complete relaxation of the patient.

Special Tests for Patellar Dislocation

In Patients who complain of knee giving out, but have no signs of ligamentous instability or meniscal pathology, the diagnosis of patellar instability should be entertained

Special Tests for Anterior Cruciate Ligament Stability

1. Lachman Test

2. Anterior Drawer Test

3. Pivot Shift Test and the related Jerk Test

Special Tests for Posterior Cruciate Ligament Stability

1. Posterior Sag

2. Reverse Lachman Test

3. Posterior Drawer Test

Investigations

1. Plain Films: The Ottawa Knee Rules may help determine the need for a Knee Xray. This may be helpful to detect an Avulsion Fracture or Tibial Plateau fracture. Likewise, osteochondral fractures may be seen.

2. MRI:

3. Ultrasound:

4. Arthroscopy:

5. Examination Under Anesthesia (EUA)

Appendix

Muscular Movement of the Knee

+++ Primary Mover

+ Secondary Mover

Index

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