Grohl's orthopedic surgeon Dr Lew Schon appeared onstage with band in Boston
Special guests performed 'How Low Can a Punk Get' at Citi Field venue
The live team-up took place in New York on Wednesday night (July 15)
The Le Soleil paper sent artist Francis Desharnais to the group's recent gig in Quebec
The gigs will take place at Milton Keynes Bowl and Edinburgh's Murrayfield Stadium
Anthony Bifolchi performed with the group in Toronto
The set lasted for just twenty minutes
Frontman says his band are playing "longer and harder than we ever have" since injury
The show took place in Toronto on Wednesday (July 8)
Foo Fighters singer appeared at the rally before his band's comeback show in Washington DC on Saturday (July 4)