Surgically treated humeral shaft fractures following shoulder arthroplasty.

BACKGROUND:
We reviewed a consecutive series of patients with a humeral fracture around either an anatomic or a reverse shoulder prosthesis treated with either open reduction and internal fixation (ORIF) or revision shoulder arthroplasty. The purposes of the study were to (1) describe the treatment of these fractures by either method, (2) report the outcomes, and (3) assess the validity of a current classification system.

METHODS:
Indications for surgery were a displaced unstable fracture, a fracture around a loose humeral stem, or a patient who was unable to tolerate conservative treatment. Outcomes were reported for two groups (patients treated with revision arthroplasty and those treated only with ORIF) and included American Shoulder and Elbow Surgeons (ASES) scores, radiographic evidence of fracture union, and complications.

RESULTS:
The mean ASES score for the entire cohort was 50.3 (95% confidence interval: 41.2 to 59.5). Thirty-five of the thirty-six fractures healed, in a mean of 7.2 months (range, 3.25 to 13.5 months). Complications occurred in fourteen (39%) of the thirty-six patients. Our ability to classify these fractures with a previously defined system had a low interobserver reliability (mean kappa, 0.37; range, 0.24 to 0.50) and a high intraobserver reliability (mean kappa, 0.69; range, 0.52 to 0.89).

CONCLUSIONS:
Periprosthetic fracture around a humeral stem implant is a difficult clinical problem involving complex decision-making. Fracture union occurred in 97% of our patients. Complications were frequent, and a reoperation was required in 19% of the patients. More than half of the patients in our study had a loose humeral component that required revision.