The powerful attacker faces yet another spell on the sidelines due to injury and could be out of action until 2013
The Iceland international recently sustained a dislocated shoulder, and it has now been decided that Sigthorsson will have to go under the knife in order to shrug off his physical problems.
Ajax have announced on their official website that the forward will undergo surgery on Friday, and will be out of action for at least four months as a result.
The shoulder surgery is yet another blow for the talented attacker after he already missed a large part of the 2011-12 campaign due to a fractured ankle.
Sigthorsson, 22, joined Ajax from AZ in the summer of 2011, but has so far made only 15 Eredivisie appearances for the Dutch giants due to his ongoing injury woes, scoring eight goals in the process.