Forearm pain associated with loose radial head prostheses.

BACKGROUND: 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.
METHODS: 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.
RESULTS: 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.
CONCLUSION: 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.