| Abstract: |
Radial head fractures are common, with an incidence of 1.7% to 5.4% of all fractures in adults and 15% of all elbow fractures in adults. There is frequently are associated soft tissue injuries such as disruption of the medial collateral ligament or interosseous membrane. Radial head excision was advocated for patients with unreconstructable fractures. However, in cases where the medial collateral ligament or interosseous membrane are injured, the radial head becomes the main stabilizer against valgus and axial forces, respectively. Several long term disabilities, including proximal radius migration, valgus instability, elbow stiffness, degenerative arthritis of the elbow and wrist, and chronic elbow, forearm, and wrist pain, have been reported when the radial head was excised in such an unstable elbow.Radial head arthroplasty commonly is used after excision of comminuted radial head fractures associated with injuries to the medial collateral ligament or the interosseous membrane or both. Silicone implant was developed in 1972 and reported their experience in 1981,this prosthesis was proposed to prevent valgus deformity at the elbow and prevent proximal radial migration. Unfortunately, clinical and biomechanical studies have shown this prosthesis does not achieve these goals. Numerous complications from silicone prostheses have been reported, including stem fracture, stem loosening, painful motion at the wrist and elbow, particulate synovitis, and osteoporosis of the capitellum. As a result of the complications associated with silicone implants, there has been increasing interest in metallic radial head implants, which prevent mixed radial migration, restore normal head sharing at the wrist, and restore elbow stability.There are two major types of metallic radial head prosthesis: the rigid prosthesis, floating radial head prosthesis. A rigid prosthesis with a modulus of elasticity near to that of bone, well contoured to the capitellum, and supplying the exact length of removed radial head should provide a better long-term result. More recently, an implant design with a so-called floating radial head has been introduced. This implant could withstand physiologic loading across the radiohumeral joint, with no radiologic changes suggestive of cartilaginous erosion.The floating prosthesis has an integrated articulation that allows both free rotation and, from any given point, a uniplanar arc of motion of 35 degrees. This, gives excellent mobility while maintaining full contact against the lateral condyle and sigmoid notch of the ulna . from a biomechanical point of view, this anatomic design may lead to longer functional lifetime compared with the standard metal prosthesis..
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