The purpose of this study was to analyze the ability to perform an anatomic radial head replacement and to study radiocapitellar prosthetic subluxation under unstable conditions. The authors used 10 intact elbows and inserted rigid uncemented, rigid cemented, and bipolar prostheses. They then measured radiocapitellar subluxation.
The results indicate that prosthesis shaft malalignment of up to 21 degrees was observed frequently. In addition, posterolateral rotatory stress after resection of 50% of the coronoid led to joint subluxation of more than 30% for the rigid prostheses. However, the bipolar prostheses self-aligned with a mean subluxation similar to the intact elbow.
This study indicates that the authors were not able to insert a radial head prosthesis in a reproducible manner. They found that one-half of the rigid radial head prostheses produced measurable malalignment compared with intact elbows. More significantly, the authors found that abnormal radiocapitellar subluxation was observed in more than half of the rigid radial head prostheses tested. The non-cemented insertion of total prostheses did not self-align. Conversely, the bipolar prostheses did correct for malpositioning of the stem. If rigid prostheses are to be used, then precise instrumentation may be necessary. Alternatively, a bipolar prosthesis may be preferable to limit joint subluxation.