Job N. Doornberg, Robert Parisien, P. Joppe van Duijn, David Ring
J. Bone Joint Surg. Am., May 2007; 89: 1075 – 1080
The radial head is now considered as one of the main stabilisers of the elbow especially in the acute setting. Once excised with impunity, the radial head is now either preserved insofar as possible, or internally fixed. Replacement is undertaken for the most traumatic injuries which may cause shortening and acute radio-ulnar dissociations and where internal fixation is likely to fail or impossible to achieve.
Radial head prosthesis have gradually moved from silicone to carbon to finally metal as failures became apparent with silicone and carbon.
This study looked at twenty-seven patients in whom a radial head replacement with modular metal spacer prosthesis had been performed to treat traumatic elbow instability. This prosthesis with a smooth polished stem is intentionally loose so that the prosthesis acts as a metal spacer and has enough mobility to adapt to the complex anatomy and motion. These patients were evaluated with use of the Mayo Elbow Performance Index (MEPI), the American Shoulder and Elbow Surgeons Elbow Evaluation Instrument (ASES), and the Disabilities of the Arm, Shoulder and Hand questionnaire (DASH). Radiographs were evaluated for arthritis, periprosthetic radiolucency, and heterotopic ossification.
Evaluation at an average follow-up of 40 months postoperatively revealed, average elbow motion of 20° flexion contracture with further 131° of flexion, 73° pronation, and 57° supination. Seven patients had undergone subsequent operations to treat residual instability, heterotopic ossification or elbow contracture, ulnar neuropathy, or misplaced metalwork. Stability was seen in 27 patients and 22 patients had a good or excellent result according to the MEPI.
This study is fairly comprehensive in numbers and follow-up. An intentionally loosely placed modular metal radial head prosthesis can help to restore stability in conjunction with repair of other fractures and reattachment of the lateral collateral ligament to the epicondyle in the setting of traumatic elbow instability with a comminuted fracture of the radial head. While a prosthesis that is too large can cause problems due to overstuffing, lucencies around the stem of the intentionally loose prosthesis and most changes in the capitellum do not appear to cause problems or translate into clinical symptoms, at least in the short term. The revision rate of about 25 % for various reasons is unsettling. Patients with radioluscencies on their radiographs need to be followed up long term to pre-empt treatment for any impending complications. Further studies are needed with significantly higher number of patients and longer follow-up for recommendation of this particular implant but the early results seem encouraging.
