The 22-year-old has undergone surgery on his groin having already been sidelined with a hernia problem, with Carl Jenkinson, Andres Santos and Bacary Sagna all still missing.Arsenal defender Kieran Gibbs has been ruled out of action of another month after undergoing surgery on his groin.The left-back, 22, had previously been unavailable for the club with a hernia problem but this latest setback will further compound Arsene Wenger\'s defensive injury woes.The coach is also without Brazilian left-back Andre Santos, who could be on the sidelines for up to three months with ankle ligament damage, whilst Bacary Sagna is yet to return from a broken leg sustained in October\'s north London derby defeat.Wenger told reporters on Friday: “Kieran Gibbs has had surgery on his left groin and he will be out for a month.”Thomas Vermaelen is likely to continue deputising on the left-flank until Gibbs’ return for Arsenal, although the French boss has refused to rule out a January move for a replacement full-back.