HOME HELP CONTACT US SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:
Sign In to gain access to subscriptions and/or personal tools.

This Article Full Text Full Text (PDF) All Versions of this Article: 36/8/1604    most recent 0363546508315198v2 0363546508315198v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Permissions Request Reprints Google Scholar Articles by Mihata, T. Articles by Lee, T. Q. PubMed PubMed Citation Articles by Mihata, T. Articles by Lee, T. Q.

Biomechanical Assessment of Type II Superior Labral Anterior-Posterior (SLAP) Lesions Associated With Anterior Shoulder Capsular Laxity as Seen in Throwers

A Cadaveric Study

Teruhisa Mihata, MD, PhD^*,,, Michelle H. McGarry, MS^*,, James E. Tibone, MD, Michael J. Fitzpatrick, MD^*,, Mitsuo Kinoshita, MD, PhD and Thay Q. Lee, PhD^*,,||

From the ^* Orthopaedic Biomechanics Laboratory, VA Long Beach Healthcare System, Long Beach, California, the University of California, Irvine, Irvine, California, Osaka Medical College, Takatsuki, Osaka, Japan, and the University of Southern California, Los Angeles, California

^|| Address correspondence to Thay Q. Lee, PhD, Orthopaedic Biomechanics Laboratory, VA Long Beach Healthcare System (09/151), 5901 East 7th Street, Long Beach, CA 90822 (e-mail: tqlee{at}med.va.gov).

Background: Type II superior labral anterior-posterior lesions in throwers are often associated with anterior shoulder capsular laxity.

Hypothesis: Shoulder instability in patients with type II superior labral anterior-posterior lesions may result from the associated shoulder capsular laxity rather than the superior labral anterior-posterior lesion alone.

Study Design: Controlled laboratory study.

Methods: Six cadaveric shoulders were externally rotated to 20% beyond the maximum humeral external rotation at 60° of glenohumeral abduction, which simulated 90° of shoulder abduction, to detach the superior labrum and elongate the anterior shoulder capsular ligaments. The detached labrum was then repaired to isolate the effect of the detached superior labrum and that of the capsular laxity. Rotational range of motion was measured at 60° of glenohumeral abduction. Anterior-posterior glenohumeral translation was measured at 30° and 60° of glenohumeral abduction. Superior-inferior glenohumeral translation was measured at 0° and 60° of glenohumeral abduction.

Results: The experimentally created type II superior labral anterior-posterior lesion and capsular laxity significantly increased anterior translation at 30° (mean difference, 1.0 ± 0.8 mm; P < .05) and 60° (mean difference, 2.2 ± 2.0 mm; P < .05) of glenohumeral abduction. Subsequent superior labral anterior-posterior repair restored the anterior translation but only at 30° of glenohumeral abduction (mean difference, 0.9 ± 0.6 mm; P < .05).

Conclusion: Because of the anterior capsular laxity associated with type II superior labral anterior-posterior lesions, superior labral anterior-posterior repair of the peeled-back superior labrum may not restore anterior glenohumeral translation at 90° of shoulder abduction.

Clinical Relevance: Anterior shoulder capsular laxity associated with type II superior labral anterior-posterior lesions may cause anterior shoulder instability at 90° of shoulder abduction in throwers even after superior labral anterior-posterior lesion repair.

Key Words: SLAP lesion • laxity • shoulder • external rotation