Osteoarthritis of the shoulder is frequently associated with posterior glenoid wear, which may be difficult to correct during shoulder arthroplasty. This study was designed to evaluate the risks that a prosthetic glenoid implanted in retroversion will loosen. The scapula, the humerus, the rotator cuff, and a total shoulder prosthesis were reconstructed with a 3-dimensional finite element model. The glenoid was placed in 5 different angles of retroversion (0°, 5°, 10°, 15°, and 20°). Location of the glenohumeral contact point, articular pressure, bone and cement stress, and micromotion around the glenoid implant were calculated during internal and external rotation. Glenoid retroversion induced a posterior displacement of the glenohumeral contact point during internal and external rotation, inducing a significant increase of stress within the cement mantel (326%) and within the glenoid bone (162%). Furthermore, a major increase of micromotion was measured at the bone-cement interface (706%). According to this study, glenoid retroversion exceeding 10° should be corrected during total shoulder arthroplasty. If the correction is impossible, not replacing the glenoid should be considered.
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Osteoarthritis of the shoulder is frequently associated with posterior glenoid wear, which may be difficult to correct during shoulder arthroplasty. This study was designed to evaluate the risks that a prosthetic glenoid implanted in retroversion will loosen. The scapula, the humerus, the rotator cuff, and a total shoulder prosthesis were reconstructed with a 3-dimensional finite element model. The glenoid was placed in 5 different angles of retroversion (0°, 5°, 10°, 15°, and 20°). Location of the glenohumeral contact point, articular pressure, bone and cement stress, and micromotion around the glenoid implant were calculated during internal and external rotation. Glenoid retroversion induced a posterior displacement of the glenohumeral contact point during internal and external rotation, inducing a significant increase of stress within the cement mantel (326%) and within the glenoid bone (162%). Furthermore, a major increase of micromotion was measured at the bone-cement interface (706%). According to this study, glenoid retroversion exceeding 10° should be corrected during total shoulder arthroplasty. If the correction is impossible, not replacing the glenoid should be considered.
Copyright remains with the authors and publisher.