# Osteomyelitis in Deep Sternal Wound Infections: Revisited—A Single-Center Observational Study

## TL;DR

This study shows that most deep sternal wound infections after heart surgery involve osteomyelitis, requiring long-term antibiotics and proper sternal fixation to prevent complications.

## Contribution

The study provides new evidence that DSWI and osteomyelitis are distinct, with implications for treatment and prevention strategies.

## Key findings

- Osteomyelitis was detected in 77% of DSWI cases.
- Long-term antibiotics did not increase reinfection rates after sternal restabilization.
- Transverse sternal fractures were less common in patients with osteomyelitis.

## Abstract

Objective: Sternum osteomyelitis and deep sternal wound infection (DSWI) are often used to describe the same clinical condition interchangeably. The aim of our current study is to investigate the prevalence of osteomyelitis in cardiac surgery patients with DSWI and its consequences in therapy and osteosynthetic reconstruction. Patients and Methods: This is a retrospective single-center observational study. All consecutive patients with DSWI after cardiac surgery between 01/2014 and 12/2019 were included. In all patients, the sternal wound was reopened, sternal closure material was removed, and negative pressure therapy was initiated. Wound swabs were taken for microbiological examination, and a bone biopsy was examined for the presence of osteomyelitis. In the presence of osteomyelitis, long-term antibiotics were administered. Results: A total of 130 patients were identified in whom DSWI occurred after sternotomy. In 102 patients (77%), osteomyelitis could be detected histopathologically. The frequency of transverse sternal fractures was lower (p < 0.05) in the osteomyelitis subgroup (63%) as compared to the non-osteomyelitis subgroup (93%). Pathogens were detected in all patients with osteomyelitis, but less frequently (p < 0.05) in the group with no osteomyelitis (64%). If osteomyelitis was treated with long-term antibiotics, there was no difference in the complication rate (reinfection) after sternal restabilization between the two groups. Conclusions: DSWI and osteomyelitis should not be used interchangeably. If osteomyelitis can be detected histopathologically, long-term antibiotic treatment should be consistently conducted. As DSWI, with or without osteomyelitis, has been suggested to be associated with inadequate or failed sternal osteosynthesis, a key strategy to reduce its risk is to ensure safe and reliable primary sternal fixation.