Stability of the unlinked Latitude total elbow prosthesis: a biomechanical in vitro analysis.

Background: The purpose of this study is to assess the valgus and varus laxity of the unlinked version of the Latitude total elbow prosthesis and the effects of radial head preservation or replacement.

Methods: Biomechanical analysis of the valgus and varus laxity of the unlinked Latitude was performed in fourteen upper limb specimens in the following conditions: (1) native elbow, (2) native elbow after the surgical approach and closing all layers again, (3) elbow with humeral and ulnar component implanted, unlinked, with the native radial head preserved, (4) elbow with humeral and ulnar component implanted, unlinked, with the native radial excised, (5) elbow with humeral, ulnar, and radial head component implanted.

Findings: After implantation of the Latitude total elbow prosthesis both the valgus and varus laxity slightly increase from mid to maximal flexion when compared to the native elbow after surgical approach. The unlinked Latitude total elbow prosthesis provides both valgus and varus stability in elbows with intact ligamentous constraints. With intact ligamentous constraints the radial head component only slightly contributes to the stability of the elbow after implantation of the unlinked Latitude total elbow prosthesis.

Interpretation: The unlinked Latitude total elbow prosthesis provides both valgus and varus stability in elbows with intact ligamentous constraints. The radial head component contributes only slightly to the stability.