Prosthetic radial head replacement is usually performed for trauma or post traumatic reconstruction. Therefore pain caused by a loose prosthesis might be incorrectly attributed to other causes. We lack reliable guidelines for diagnosing a loose radial head prosthesis that is symptomatic. Experience in Hip Arthroplasty has identified thigh pain as originating from the bone-prosthesis interface in the femoral canal, as opposed to the acetabulum or hip joint itself. The authors have recognized a similar phenomenon with radial head prostheses that has not yet been reported in the literature. Pain from a loose stem within the proximal radius may present as 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. From August 1999 to December 2006, 9 consecutive patients (10 cases) required revision surgery for painful aseptic loosening of a primary metal prosthetic radial head implant. One of the 9 patients required re-revision with a longer stem. A further 4 patients with symptomatic aseptic loosening have not yet been revised. 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 with no evidence of 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 forearm pain. Revision or prosthetic removal eliminated the pain in 7 of 10 cases and decreased it in 1 Most of the patients who had relief of their forearm pain could tell in the first few days that the pain was gone following revision or removal of the loose radial head prosthetic component. One patient with moderate pain had an arthritic elbow and had no significant lasting relief from surgery. One patient was lost to follow-up. Follow-up averaged 27 months (range 1 to 66 months). Three of the 4 patients who had not yet undergone revision, were still awaiting revision and one did not want further surgery.

In conclusion, the presence of radial sided proximal forearm pain in a patient with a radial head prosthesis is a strong indicator of symptomatic aseptic loosening. If the prosthesis has a textured surface for bone ingrowth, and was inserted without cement, we now consider this symptom to be diagnostic even in the absence of radiographic signs of loosening.