The focus of this prospective observational study is to (1) establish the range and variation associated with bone/soft tissue perfusion in fracture patients, using ICG fluorescence imaging; (2) examine the relationship between perfusion and complications such as surgical site infection (SSI), persistent SSI, and fracture nonunion; (3) to determine whether the quantitative ICG fluorescence can be used to guide bony debridement in the setting of infected fracture to minimize complications.

This will be a prospective observational trial to better understand the range and variation associated with bone/soft tissue perfusion in fracture patients and examine the relationship between perfusion, measured using quantitative Indocyanine green (ICG) fluorescence and complications such as surgical site infection (SSI), persistent SSI, and fracture nonunion. Primary outcome measure is complication (either infection, recurrent infection or nonunion).

Eligible consenting patients will receive standard of care treatment for their fracture or infection including irrigation and debridement of their operative site and/or fracture fixation. After exposure, 0.1 mg/Kg ICG will be injected intravenously and video rate ICG fluorescence images will be acquired 20 seconds before and 4 minutes after the injection, each before and after debridement.

A subset of 30 post-fracture complication patients will undergo surgical treatment for their infection in Center of Innovation Surgery (CIS) and have either an intraoperative Dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) after exposure but before the ICG injection or a preoperative DCE-MRI. Patients receiving surgery in the CIS will be required to sign an additional CIS-specific consent document.

The need for repeat surgical procedure will be left up to the treating surgeon. If repeat procedure is needed, pre- and post-debridement quantitative ICG fluorescence images will be obtained at each procedure.

Study participants will be followed at 2 weeks, 6 weeks, 3 months, 6 months, and one year from their index study surgery. Complication including index infection, recurrent infection or delaying union/nonunion will be identified at the time of diagnosis and/or during each participants assessment that occurs during routine outpatient clinic visit. Detailed information on the infection including date of diagnosis, participant signs and symptoms, culture test results, method of treatment(s), and date of resolution will be documented.

Inclusion Criteria:

Established SSI Fracture (Cohort Cohort 1, Group 1)

1. Patients 18 years of age or older.
2. Extremity fracture.
3. Prior definitive fracture management with external fixation, internal fixation, or joint fusion.
4. Superficial, deep, or organ space SSI (as per CDC criteria) at the fracture site that requires operative management.
5. Will have all fracture care surgeries performed by a participating surgeon or delegate.
6. Provision of informed consent.

Subset: DCE-MRI (Cohort 1-1, Group 2)

1. Patients 18 years of age or older.
2. Closed extremity fracture.
3. Planned definitive fracture management with external fixation, internal fixation, or joint fusion.
4. Will have all planned fracture care surgeries performed by a participating surgeon or delegate.
5. Provision of informed consent.

Exclusion Criteria:

Established SSI Fracture Cohort (Cohort 1, Group 1)

1. Fracture of the hand.

2. Iodine allergy.

3. Received previous surgical debridement to manage the SSI.

4. Incarceration.

5. Problems, in the judgment of study personnel, with maintaining follow-up with the patient.

   Subset: DCE-MRI (Cohort 1-1, Group2)

6. the presence of an electronic implant, such as a pacemaker

7. the presence of a metal implant, such as an aneurysm clip

8. the presence of other contraindication(s), as determined by the MRI technologists and radiologists.

9. A history of allergy to iodides

10. A GFR < 30 ml/min as determined by blood test on the day of NIR/MR imaging, or from lab results within 3 months of DCE-MRI for this study

Patients 18 years of age or older who present with SSI following fracture or joint fusion Established SSI fracture cohort (Cohort 1). A subset of Cohort 1 will be considered for the Subset DCE-MRI cohort (Cohort 1-1).