Failure of a Unipolar Radial Head Prosthesis Due to Component Dissociation

Radial head implant arthroplasty is a consideration for the treatment of comminuted, unreconstructable fractures of the radial head. Many prosthetic designs exist and can be unipolar or bipolar, each of which can be cemented or noncemented. For most unipolar designs, a prosthetic stem is first implanted into the proximal radius. The prosthetic radial head is then impacted onto a morse taper on the stem or secured with a set screw. There is little information published on the mechanisms of failure for radial head implants, regardless of design. The authors found 2 individual case reports that describe component dissociation in bipolar implants. They could find no individual case reports of implant failure due to component dissociation of a unipolar implant related to failure of the set screw. The authors describe such a case 5 years after unipolar radial head implant arthroplasty. The system used employs a set screw to secure the prosthetic head onto the stem. The patient subsequently had a successful outcome after implant removal without reimplantation. Orthopedic surgeons have many options when considering radial head replacement implants and should be aware of the potential complications of each. The authors present this case to show one potential complication of unipolar prosthetic radial head implant arthroplasty. [Orthopedics. 2016; 39(4):e771-e774.].