After post-traumatic radial head replacement, pain caused by a loose prosthesis might incorrectly be assumed to be post-traumatic. Reliable guidelines for diagnosing a symptomatic loose radial head prosthesis are lacking. We noted that pain from a loose stem within the proximal radius may present as proximal radial forearm pain.
The medical records and radiographs of 14 consecutive cases (13 patients) with proximal radial forearm pain associated with a loose radial head prosthesis were reviewed retrospectively. The indication for revision surgery was painful loosening of the prosthesis within the canal of the proximal radius in 7 patients (8 cases) and pain without preoperative confirmation of the loosening in 2 patients (2 cases). Various prosthetic designs had been used in the primary operations.
In 12 of 14 cases, the loosening was evident radiographically, but in 2 the only indication of a loose prosthesis (confirmed surgically) was proximal radial forearm pain. One patient was lost to follow-up. Revision or prosthetic removal eliminated the pain in 7 of 9 cases and decreased it in 1. One patient with moderate pain had an arthritic elbow and had no significant lasting relief from surgery. Follow-up averaged 27 months.
The presence of proximal radial forearm pain in a patient with a radial head prosthesis is an indicator of symptomatic mechanical loosening. If the prosthesis has a textured surface for bone ingrowth, and was inserted without cement, we now consider this a strong indicator of loosening, even in the absence of radiographic signs.