McKenna took the field for the first time in 2020 on Saturday night in his side’s clash with North Melbourne following the drama of his initial positive COVID-19 test last month.
The 24-year-old is expected to go under the knife after scans on Sunday revealed a finger fracture.
The Bombers are hopeful McKenna will not be sidelined for a long period of time.
He showed he remains an important player for the Bombers, providing dash and flair across 18 disposals in their win against North Melbourne.
Essendon come up against the Western Bulldogs this Friday night at Metricon Stadium.