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An evaluation of the anatomic basis of the O'Brien active compression test for superior labral anterior and posterior (SLAP) lesions.

Background: The O'Brien test is a widely known method for evaluating superior labrum anterior and posterior (SLAP) lesions of the shoulder (Brukner and Kahn 2007). As originally described by O'Brien et al (1998), this test (termed the active compression test) was developed as a diagnostic tool for both labral and acromioclavicular (AC) joint problems, and involves maintaining two shoulder positions against a downward force. The first position is in shoulder flexion 90?, horizontal adduction 10-15?, and full internal rotation (thumb down) with the elbow extended. The second position is the same, but with full external rotation (palm up). A positive test results if pain or painful clicking is elicited during the first position, and reduced or eliminated in the second. Symptoms 'on top of the shoulder' are considered positive for AC abnormality, and those 'inside the glenohumeral joint itself' positive for labral abnormality. The authors propose that the test acts by loading the AC joint from below, and generating tension in the bicipital-labral complex.

Aim: To evaluate the anatomic basis of the O'Brien test for SLAP lesions (specifically, to quantify the active and passive tension in the long head of biceps during the O'Brien test).

Methods: Two complementary studies were performed, one evaluating the active and the other the passive tension in the long head of biceps. Each measured tension in the positive (shoulder flexion, horizontal adduction, and internal rotation) and negative (shoulder flexion, horizontal adduction, and external rotation) positions of the O'Brien test. To clarify the point of examiner contact each position was performed with resistance against the arm above the elbow and again below the elbow.

Active tension was studied in six female volunteers (mean age 21.2 (SD 1.7) years) and six male volunteers (mean age 23.5 (SD 3.7) years) with no history of shoulder problems using surface electromyography (EMG). Muscle recordings were taken from the long and short head of biceps, and the anterior and middle portions of deltoid. Passive tension was measured in three female cadavers (age 58-91 years) using a load cell directly attached to the proximal long head of biceps tendon.

Results: As measured by surface EMG the long head of biceps was more active in the negative than positive position of the O'Brien test in normal volunteers. This was found against both arm resistance (63% more active) and forearm resistance (88% more active). In the cadaveric specimens, passive tension in the long head of biceps was greater in the negative (201 g) than the positive position (-738 g).

Discussion: The study findings are contrary to the proposal by O'Brien et al (1998) that the positive position of the O'Brien test increases tension in the bicipitallabral complex. The increases in active and passive tension in the negative position have an anatomical basis. Shoulder external rotation brings the biceps onto the anterior aspect of the arm, allowing this muscle to actively contribute to shoulder flexion. It also lengthens the intra-articular path of the long head of biceps, thus increasing passive tension. The lack of support for the anatomical basis of the O'Brien test may partly explain variable reports of the clinical accuracy of this test.

REFERENCES

Brukner P and Khan K (2007): Clinical Sports Medicine. Sydney; London: McGraw-Hill.

Kim S-H, Ha K-I, Ahn J-H, Kim S-H, Choi H-J (2001): Biceps load test II: A clinical test for SLAP lesions of the shoulder. Arthroscopy: The Journal of Arthroscopic & Related Surgery 17: 160-164.

Mirkovic M, Green R, Taylor N, Perrott M (2005): Accuracy of clinical tests to diagnose superior labral anterior and posterior (SLAP) lesions. Physical Therapy Reviews 10: 5-14.

Munro W, Healy R (2009): The validity and accuracy of clinical tests used to detect labral pathology of the shoulder--A systematic review. Manual Therapy 14: 119-130.

Myers TH, Zemanovic JR, Andrews JR (2005): The resisted supination external rotation test. The American Journal of Sports Medicine 33: 1315-1320.

O'Brien SJ, Pagnani MJ, Fealy S, McGlynn SR, Wilson JB (1998): The active compression test: A new and effective test for diagnosing labral tears and acromioclavicular joint abnormality. The American Journal of Sports Medicine 26: 610-613.

Commentary

This excellent study takes a back-to-school approach to examining the O'Brien test for SLAP lesions, and reveals that the anatomical basis is not supported. For clinicians, this is both important and useful. Studies of clinical tests for SLAP lesions have shown poor accuracy, and considerable variability (Mirkovic et al 2005, Munro and Healy 2009). Historically, new tests have been developed and reported to have good accuracy, but researchers re-evaluating the same tests have not produced such good results (Munro and Healy 2009). With such findings, re-examining the validity of SLAP tests is highly appropriate.

Clinically, differential diagnosis of a SLAP lesion requires careful objective testing, as well as careful interpretation of the findings. New clinical tests for SLAP lesions are still emerging (Kim et al 2001, Myers et al 2005), but none has proven definitive. In this environment, evidence-based practice is less about applying the "best" test, and more about applying a reasoned approach to diagnosis. An understanding of the structures under stress during the physical examination is essential, as highlighted by Green et al (2008).

Clinicians utilising the O'Brien test in the diagnosis of SLAP lesions should find this article of interest. It provides a reasoned critique of the anatomical basis of the O'Brien test, and represents an opportunity to review your own differential diagnosis of SLAP lesions.

Ewan Kennedy, BPhty, PhD

Professional Practice Fellow, School of Physiotherapy, University of Otago

Journal of Shoulder and Elbow Surgery 17: 165-171. (Abstract prepared by Ewan Kennedy)
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Article Details
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Title Annotation:Clinically Applicable Papers
Author:Green, R.A.; Taylor, N.F.; Mirkovic, M.; Perrott, M.
Publication:New Zealand Journal of Physiotherapy
Article Type:Report
Geographic Code:8NEWZ
Date:Jul 1, 2009
Words:926
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