Ryan M Degen1, Joshua W Giles2, Harm W Boons1, Robert B Litchfield1, James A Johnson2, George S Athwal1
1 Department of Orthopedic Surgery, The University of Western Ontario, London, Ontario, Canada
2 Mechanical and Materials Engineering, The University of Western Ontario, London, Ontario, Canada
Background : The coracoacromial ligament (CAL) is an important restraint to superior shoulder translation. The effect of CAL release on superior stability following the Latarjet is unknown; therefore, our purpose was to compare the effect of two Latarjet techniques and allograft reconstruction on superior instability.
Materials and Methods : Eight cadaveric specimens were tested on a simulator. Superior translation was monitored following an axial force in various glenohumeral rotations (neutral, internal, and external) with and without muscle loading. Three intact CAL states were tested (intact specimen, 30% glenoid bone defect, and allograft reconstruction) and two CAL deficient states (classic Latarjet (classicLAT) and congruent-arc Latarjet (congruentLAT)).
Results : In neutral without muscle loading, a significant increase in superior translation occurred with the classicLAT as compared to 30% defect (P = 0.046) and allograft conditions (P = 0.041). With muscle loading, the classicLAT (P = 0.005, 0.002) and the congruentLAT (P = 0.018, 0.021) had significantly greater superior translation compared to intact and allograft, respectively. In internal rotation, only loaded tests produced significant results; specifically, classicLAT increased translation compared to all intact CAL states (P < 0.05). In external rotation, only unloaded tests produced significant results with classicLAT and congruentLAT allowing greater translations than intact (P ≤ 0.028). For all simulations, the allograft was not significantly different than intact (P > 0.05) and no differences (P = 1.0) were found between classicLAT and congruentLAT.
Discussion: In most simulations, CAL release with the Latarjet lead to increased superior humeral translation.
Conclusion: The choice of technique for glenoid bone loss reconstruction has implications on the magnitude of superior humeral translation. This previously unknown effect requires further study to determine its clinical and kinematic outcomes.
George S Athwal
The Hand and Upper Limb Centre St. Joseph's Health Care London, 268 Grosvenor St., London, ON. N6A 4L6
Source of Support: None, Conflict of Interest: None
[FULL TEXT] [PDF]*