This article describes a technique in which measurements are obtained from radiographs of the contralateral, normal elbow to predict the magnitude of overlengthening resulting from use of a metallic radial head prosthesis.
Step 1: Obtain Bilateral Elbow Radiographs
Obtain bilateral digital anteroposterior radiographs of the elbows that are orthogonal to the forearm in 45° of flexion and neutral forearm rotation.
Step 2: Perform Radiographic Measurements of the Contralateral, Normal Elbow
Draw the angle on the radiograph of the normal elbow.
Step 3: Perform Radiographic Measurements of the Radial Head Implant
Draw the same lines and angle and perform the same measurements on the implant radiograph.
Step 4: Calculate Radial Head Implant Length
The virtual length of the native radial head implant (L-NRH) is subtracted from the virtual length of the radial head implant (L-RHI), which results in the magnitude of the radial head implant overlengthening in millimeters: (L-RHI) – (L-NRH) = overlengthening.
The radiographic measurement technique was validated in a cadaveric study.
What to Watch For
Pitfalls & Challenges