Capitellar erosion after radial head arthroplasty: A comparative biomechanical study of operated radial head fractures on cadaveric specimens.

BACKGROUND

We asked whether open reduction and internal fixation (ORIF) or radial head arthroplasty (RHA), common techniques used for the confrontation of displaced or comminuted radial head fractures, are correlated with cartilage wear of the capitulum.

HYPOTHESIS

We hypothesized that neither ORIF nor RHA are correlated with capitellar cartilage wear.

MATERIAL AND METHODS

On 5 cadaveric elbow specimens, osteotomies were employed to simulate radial head comminuted fractures followed with ORIF by Herbert screws. Radial heads were also excised from other 5 cadaveric elbow specimens and were replaced by metallic monopolar implants. Finally, 2 elbows were not operated and used as a control group. Custom-made rotary machines, working unstoppably, generated 700,000 pronation and supination forearm movements at a 110° arc of motion. The elbow joints were examined with pre- and postoperative magnetic resonance imaging (MRI) scans and the articular surfaces of the capitula were resected and sent for histopathology study.

RESULTS

In the 2 cadaveric elbows of the control group and the 4 elbows treated with ORIF, no cartilage damage was found. The fifth one displayed cartilage fissures, which were, classified according to International Cartilage Repair Society (ICRS) grading system as grade I cartilage damage. On the contrary, all 5 elbows treated with RHA sustained complete cartilage loss, exposure of the subchondral bone and were classified as ICRS grade IV cartilage damage.

DISCUSSION

Our study suggests that metallic monopolar RHA after a displaced or comminuted radial head fracture carries a high risk of rapidly evolving cartilage loss of the capitulum.