Patellar Glide Test (or Patellar Mobility Test) is a manipulative test to demonstrate passive patellar mobility and evaluate the instability of the patella by passively pushing the patella medially and laterally in the relaxed patient.
See Also: Patellar Grind Test
The Patellar Mobility Test is performed with the patient in supine position, and the knee in full extension (0°) and flexed to 30°.
The examiner stands at the patient’s side next to the knee and grasps the proximal half of the patella with the thumb and index finger of one hand and the distal half with the thumb and index finger of the other.
For the lateral patellar glide test, the examiner’s thumbs push the patella laterally over the lateral femoral condyle and the index fingers resting there.
For the medial patellar glide test, the examiner’s index fingers push the patella in the opposite direction.
In each case, the examiner’s index finger or thumb can palpate the projecting posterior surface of the patella. Where increased lateral mobility is suspected, the same test is performed to assess stability with the quadriceps tensed.
The patient is asked to lift his or her foot on the examining table. The examiner then notes the resulting motion of the patella.
The medial and lateral patellar glide tests provide information about the degree of tension in the medial or lateral retinaculum, respectively.
The tests should always be performed comparatively on both knees.
With the hands in the same position, the examiner can also place traction on the patella by lifting it o the condyles.
Normal physiologic findings include painless, symmetrical mobility of both patellae without any crepitation or tendency to dislocate. Increased lateral or medial mobility of the patella suggests laxity of the knee ligaments or habitual patellar subluxation or dislocation.
To define patellar mobility, the patella is divided longitudinally into four equal quadrants:
A hypomobile patella is defined as one that cannot be mobilized medially or laterally over one quadrant.
A hypermobile patella is one that can be moved two quadrants, or one-half of the patellar width, medially or laterally.
Crepitation (retropatellar friction) occurring when the patella is mobilized suggests chondropathy or retropatellar osteoarthritis (positive glide test).
Normal lateral glide is up to 2.5 quadrants, more than 3 quadrants indicates abnormal medial restraint.
Normal medial glide is 1 to 2.5 quadrants, less than 1 quadrant glide indicates tight lateral restraint. More than 3 quadrants is hypermobile patella.
With the hands in the same position, the examiner can expand the test by moving the patella distally. Decreased distal mobility of the patella suggests shortening of the rectus femoris or patella alta (high-riding patella).
The lateral patellar glide test is also known as the Fairbank’s sign or patellar apprehensive test. Therefore, it should be performed after the medial glide testing.
The medial patellar femoral ligament (MPFL) is the main restraint to the lateral dislocation. The MPFL can be evaluated with the knee in full extension and the patella medially subluxated with the thumb as in the glide test.