gms | German Medical Science

Objectives: The labrum is a crucial static stabilizer of the glenohumeral joint and labral reconstruction may play a role in the treatment of glenohumeral joint instability in the setting of a deficient or torn labrum. The Anterior Labral Circumferential Onlay (ALCO) technique reconstructs the labrum using the long head of the biceps tendon (LHBT).

Hypothesis: It has been hypothesized that the ALCO technique would restore glenohumeral joint stability in a cadaveric model (1) comparable to the native state and (2) comparable to or better than a Latarjet procedure.

Methods: Ten fresh-frozen cadaveric shoulders were tested using a 6-degrees-of-freedom robotic arm in 6 consecutive states:

1.

native,

2.

capsular repair,

3.

labral tear,

4.

ALCO technique, and

5.

Latarjet.

Biomechanical testing consisted of 80 N of anterior-inferior force and 50 N of compression at 90 degrees of humero-thoracic abduction. Lateral displacement and a dislocation force ratio were measured.

Results and conclusion: The lateral translation of the humeral head during dislocation in the native state was 6.5 mm and decreased to 5.4mm (p<0.001) in the labral tear state. The lateral translation of the humeral head was restored to 6.4 mm (p<0.001) with the ALCO technique, showing no difference from the native state.

The force ratio was 1.8 in the native state, decreased to 1.1 in the labral tear state and was 1.4 (p<0.001) with the ALCO technique, showing no difference from the native state.

The Latarjet technique restored the force ratio to 1.3 (not significantly different from native) but failed to restore lateral translation with a value of 5.6 mm (p=0.003 from native, not significantly different from the labral tear).

The ALCO is a novel technique for labral reconstruction that may have a role in the treatment of anterior glenohumeral instability in the setting of a deficient labrum. In this study, the ALCO technique restored native stability ratio and lateral humeral translation.

Clinical relevance: This study proposes and biomechanically validates the ALCO technique as a surgical technique for labral reconstruction that may have a role in treating patients with chronic anterior shoulder instability.