Comparison of glenohumeral contact pressures and contact areas after glenoid reconstruction with latarjet or distal tibial osteochondral allografts.

Background: Glenoid reconstruction with distal tibial allografts offers the theoretical advantage over Latarjet reconstruction of improved joint congruity and a cartilaginous articulation for the humeral head. Hypothesis/Purpose: To investigate changes in the magnitude and location of glenohumeral contact areas, contact pressures, and peak forces after (1) the creation of a 30% anterior glenoid defect and subsequent glenoid bone augmentation with (2) a flush Latarjet coracoid graft or (3) a distal tibial osteochondral allograft. It was hypothesized that the distal tibial bone graft would best normalize glenohumeral contact areas, contact pressures, and peak forces. Study Design: Controlled laboratory study. Methods: Eight cadaveric shoulder specimens were dissected free of all soft tissues and randomly tested in 3 static positions of humeral abduction with a 440-N compressive load: 30 degrees, 60 degrees, and 60 degrees of abduction with 90 degrees of external rotation (ABER). Glenohumeral contact area, contact pressure, and peak force were determined sequentially using a digital pressure mapping system for (1) the intact glenoid, (2) the glenoid with a 30% anterior bone defect, and (3) the glenoid after reconstruction with a distal tibial allograft or a Latarjet bone block. Results: Glenoid reconstruction with distal tibial allografts resulted in significantly higher glenohumeral contact areas than reconstruction with Latarjet bone blocks in 60 degrees of abduction (4.87 vs 3.93 cm(2), respectively; P < .05) and the ABER position (3.98 vs 2.81 cm(2), respectively; P < .05). Distal tibial allograft reconstruction also demonstrated significantly lower peak forces than Latarjet reconstruction in the ABER position (2.39 vs 2.61 N, respectively; P < .05). Regarding the bone loss model, distal tibial allograft reconstruction exhibited significantly higher contact areas and significantly lower contact pressures and peak forces than the 30% defect model at all 3 abduction positions. Latarjet reconstruction also followed this same pattern, but differences in contact areas and peak forces between the defect model and Latarjet reconstruction in the ABER position were not statistically significant (P > .05). Conclusion: Reconstruction of anterior glenoid bone defects with a distal tibial allograft may allow for improved joint congruity and lower peak forces within the glenohumeral joint than Latarjet reconstruction at 60 degrees of abduction and the ABER position. Although these mechanical properties may translate into clinical differences, further studies are needed to understand their effects. Clinical Relevance: Glenoid bone reconstruction with a distal tibial osteochondral allograft may result in significantly improved glenohumeral contact areas and significantly lower glenohumeral peak forces than reconstruction with a Latarjet bone block, which could play a role in improving postoperative outcomes after glenoid reconstruction.