The impact of anatomic alignment on radiocapitellar pressure following radial head arthroplasty

Abstract

BackgroundThe incidence of radial head fractures is increasing, and radial head arthroplasty (RHA) is being more frequently utilized as treatment for irreparable fractures. Our objective was to compare radiocapitellar pressure between the native joint and two radial head prosthesis conditions - (1) a prosthetic head that was aligned to the forearm axis of rotation and (2) the same prosthesis with an axisymmetric nonaligned head. MethodsTen cadaveric specimens received a pressfit radial head prosthesis (Align, Skeletal Dynamics, Miami, FL) for both prosthetic testing conditions. Anatomic alignment (AL) was defined as the prosthetic head aligned to the forearm axis of rotation. Axisymmetric alignment (NA) was defined as the prosthetic radial head aligned to the axis of the prosthetic stem. Axial load was applied with the elbow in extension and the forearm pronated. Data was collected using a Tekscan 4000 sensor. ResultsThe mean pressure in the AL and AX groups were significantly higher than the mean pressure in the native joint. Compared to the native joint, the mean pressure was 19% higher in the AL group and 56% higher in the AX group. Peak pressure beyond 5 MPa occurred in zero specimens in the native joint group, in one specimen (10%) in the AL group, and in five specimens (50%) in the AX group. DiscussionOur results demonstrated that a pressfit radial head prosthesis aligned with the forearm axis of rotation yields capitellar pressures that were more similar to the native condition than a non-aligned pressfit prosthesis. These findings suggest that anatomic alignment may optimize capitellar wear properties, improving the long-term durability of radial head arthroplasty.