Elbow Arthroplasty - Instability

Instability is typically a complication of unlinked prostheses. Rates of instability following unlinked total elbow replacements have been reported in the range up to 13% [9].

Elbow joint stability is maintained by statistic and dynamic restraints. The ulnohumeral articulation, the anterior bundle of the meial collateral ligament, and the lateral ulnar collateral ligament are the three main contributors to static restraint in the elbow. The surrounding elbow musculature constitutes the dynamic restraint system. Compromise of any of the aforementioned structures can increase the risk of postoperative instability.

Unlinked total elbow replacements depends more heavily on static restraints for stability than linked total elbow replacements.
        Dislocated unlinked total elbow replacement

Although much less common, instability can also be seen following linked TEA. Instability in linked TEA is usually caused by wear of the polyethylene bushings or disengagement of the linkage pin. Proper prosthesis alignment is crucial in linked arthroplasty as malalignment can cause abnormal forces to be generated across the joint which can lead to early hardware failure.

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