Radial head fractures are often associated with complex osteoligamentous injuries. Mild elbow stiffness, posterolateral rotatory instability (PLRI), and persistent impairment often lead to revision surgery.

The aim of the study was to present a complicated course after radial head fracture with posttraumatic radial head deformity, which led to chronic PLRI due to the so-called cam effect.

A young, active man suffered a bilateral radial head fracture. While the Mason type I radial head injury healed without sequelae, the Mason type III injury on the opposite side was followed by several revisions due to arthrofibrosis, advanced chondromalacia, and increasing head deformity, which led to recurrent PLRI. In addition to the analysis of the individual pathogeneses and revisions as well as a detailed explanation of the last revision surgery, a clinical follow-up was carried out 12 months after the last revision with examination of the range of motion and collection of patient-reported outcome measures (PROM).

Four revision operations were performed. After open metal removal and arthrolysis, a lateral ulnar collateral ligament (LUCL) reconstruction was performed for proven PLRI, followed by another arthroscopic arthrolysis with evidence of recurrent instability. The cause of the elongation/insufficiency of the ligament reconstruction was the deformed radial head, which was corrected in the fourth revision together with a revision LUCL reconstruction comprising radial head plasty. At the final follow-up, the patient was satisfied and there was no pain and instability. Extension/flexion was 0‑0-135° with free pronation/supination at 80-0-80°. The PROMs showed good overall results.

Revision surgeries are frequently required to address complex posttraumatic conditions following radial head fractures. Early arthroscopic instability testing is recommended to promptly identify and address PLRI if there are ongoing complaints. In addition to ligament stability, it is essential to restore the bony anatomical alignment, since bony deformity of the radial head can contribute to decentration of the humeroradial column and progressive elongation of the LUCL/LCL complex, leading to a recurrence of PLRI due to the cam effect.