Patellar apprehension test for lateral patellainstabilitet

The Moving Patellar Apprehension Test is a clinical examination used to identify lateral patellar instability, including tendencies toward patellar subluxation or dislocation. It is especially relevant for patients with a history of patellar dislocation or chronic instability【1】.

Test Procedure

The test consists of two parts:

1. Provocation Test

Purpose: To reproduce the patient’s typical symptoms and apprehensive reaction.

Execution:

• The patient lies supine with the knee fully extended.

• The examiner places the thumb on the patella and applies a lateral force, pushing the patella outward.

• The knee is gradually flexed to 90° while maintaining the lateral force.

• The knee is then returned to full extension, still with lateral force applied.

Positive test:

• The patient expresses discomfort or fear of patellar dislocation.

• The quadriceps contracts reflexively as a protective response.

2. Symptom-Relieving Maneuver

Purpose: To evaluate whether medial stabilization reduces symptoms.

Execution:

• The test is repeated, but this time the examiner applies a medial force on the patella using the index and middle fingers.

• The knee is again moved from extension to 90° flexion and back while maintaining medial force.

Positive test:

• The patient’s symptoms are relieved, with improved movement and less discomfort compared to the provocation test.

Tolkning av testresultater

Resultat	Tolkning
Positiv test	Indikerer lateral patellainstabilitet, ofte sett ved tidligere patellaluksasjon eller subluksasjon.
Negativ test	Ingen tydelig apprehensjon eller smerte → lav sannsynlighet for patellainstabilitet.

Interpretation of Results

Result	Interpretation
Positive test	Indicates lateral patellar instability, commonly seen in patients with a history of patellar subluxation or dislocation.
Negative test	No apprehension or pain, suggesting a low likelihood of patellar instability.

Scientific Evidence

A study comparing the test with patellar stability under anesthesia reported the following diagnostic accuracy【2】:

• Sensitivity: 100% (excellent ability to detect instability)

• Specificity: 88.4% (good ability to exclude false positives)

• Positive Predictive Value (PPV): 89.2%

• Negative Predictive Value (NPV): 100% (a negative test strongly rules out instability)

Conclusion

The Moving Patellar Apprehension Test is a highly sensitive and clinically valuable tool for assessing lateral patellar instability. A positive result strongly supports a history of patellar dislocation or chronic instability. The test should be interpreted in the context of patient history and, when needed, supported by imaging studies.

Sources:

1. Ahmad CS, McCarthy M, Gomez JA, Shubin Stein BE. The moving patellar apprehension test for lateral patellar instability. Am J Sports Med. 2009 Apr;37(4):791-6. Epub 2009 Feb 3.

2. Clinically Relevant Technologies, http://www.youtube.com/watch?v=4TJaS4IAUVk ;accessed May 2011