There are two main categories of elbow arthroplasty:
- Total Elbow Replacement
Hemiarthroplasty replaces either the head of the radius, the distal humerus, or the proximal ulna with an intradedullary stemmed implant. Humeral and ulnar hemiarthroplasties are no longer used due to their high rates of failure.
Radial head hemiarthroplasties are used for comminuted radial head fractures, much like hip arthroplasties are used for Garden III and IV fractures.
Titanium radial head implant
Total Elbow Replacements employ both humeral and ulnar components. Few modern components incorporate a replacement for the head of the radius.
Previously, terms such as constrained, unconstrained, hinged and resurfacing were used to describe otal elbow replacements. Today, the most appropriate terminology used is linked and unlinked. The reason being that some devices can be significantly constrained, but are not mechanically linked, and vice-versa.
Linked (Coupled): the first generation designs for lined total elbow replacements centered around a single axis metallic hinge. Loosening, especially of the humeral component was a serious complication of this design. Modern designs adopt the use of a pin which allows for a small degree of rotation and varus-valgus motion. This effectively allows the surrounding tissues to bear some of the stress during motion. While this decreases the incidence of loosening to a degree, it is still considered a disadvantage when compared to unlinked total elbow replacements. The advantage to a linked design is that the joint is immediately rendered stable. Hence it is a treatment that can be applied to a broad spectrum of pathologies, especially where there is ligamentous deficiency or trauma, such as in acute fractures, posttraumatic arthrosis, distal humeral nonunion, posttraumatic ankylosis, and posttraumatic instability. Revision of a failed total elbow replacement is also most reliably managed using a linked system.
|The Acclaim linked total elbow arthroplasty system|
Unlinked (Uncoupled): These prostheses have no linkage pin between the humeral and ulnar components. The components attempt to recreate normal anatomy with the intent to divert stress for the bone-implant interface to the surrounding musculature and soft tissues. This helps to prevent hardware loosening. Unlinked prosthesis are suitable for patients with reasonable preservation of bone and elbow joint stability. The main disadvantage ot unlinked prostheses is a higher rate of dislocation. Good surgical technique in bone preparation is imperative for maintaining alignment of the two components. Adequate soft tissue balance is required to prevent dislocation.
|The Acclaim unlinked total elbow arthroplasty system.|