The stabilization effect of the conjoint tendon in reverse total shoulder arthroplasty. (March 2019)

• Record Type: Journal Article
• Authors: Pastor, M.-F.; Ferle, M.; Hagenah, J.; Ellwein, A.; Wellmann, M.; Smith, T.
• Is Part Of: Clinical biomechanics. Volume 63(2019)
• Page Start: 179
• Page End: 184
• Publication Date: 2019-03
• Subjects: Reverse total shoulder arthroplasty -- Conjoint tendon -- Glenosphere lateralisation -- Anterior stability; Biomechanics -- Periodicals; Osteopathic medicine -- Periodicals; Biomechanics -- Periodicals; Osteopathic Medicine -- Periodicals; 612.76
• DOI: 10.1016/j.clinbiomech.2019.03.009
• Languages: English
• ISSNs: 0268-0033

Abstract

Abstract: Background: Numerous factors determine stability of reverse total shoulder arthroplasty. The effect of the conjoint tendon in relation to stability remains unknown. In this biomechanical study, we evaluated the influence of the conjoint tendon on the anterior stability of reverse total shoulder arthroplasty with a hemispherical glenosphere and a glenosphere with 9 mm lateralisation. Methods: A reverse total shoulder arthroplasty was implanted in 6 human cadaveric shoulders. The anterior stability was evaluated using a shoulder simulator. Two conditions, intact and dissected conjoint tendon, and 2 component configurations, a hemispherical glenosphere and a glenosphere with 9 mm lateralisation, were tested in each specimen. Testing of anterior stability was performed in 30° and 60° of abduction, with 0° and 30° of external rotation in the glenohumeral joint. Findings: The conjoint tendon showed a significant influence on the anterior stability with a hemispherical glenosphere in 30° and 60° with neutral rotation (p = 0.028) as well as 30° abduction with 30° (p = 0.028) external rotation. The 9 mm lateralised glenosphere stabilized significantly reverse total shoulder arthroplasty with resected conjoint tendon compared to the hemispherical glenosphere with resected conjoint tendon (p = 0.028). Interpretation: In a biomechanical setting the conjoint tendon has a stabilizing influence on the anterior stability of the reverse total shoulder arthroplasty with a hemispherical glenosphere in an abducted arm position, but this stabilizing effect was not seen with the lateralised glenosphere. The single influence of the lateralisation of the glenosphere on anterior stability was shown in cases of resected conjoint tendon. Highlights: First study investigating the stabilizing effect of conjoint tendon The conjoint tendon increased the anterior stability of reverse shoulder arthroplasty. This stabilizing effect was not observed with lateralisation of the glenosphere. The influence of the glenoidal lateralisation was shown with resected conjoint tendon.