Although it was initially suspected that the 34-year-old Belgian Classics star had fractured his collarbone, a medical examination revealed that he had suffered from an acromioclavicular (AC) joint dislocation.
Boonen's surgical procedure was undertaken in a hospital in Herentals, and his Etixx-QuickStep team reports that it went well.
"The joint is stable and the surgery went well," Doctor Yvan Vanmol said via a team statement.
"It's too early to state a precise time of recovery, which will depend on the evolution of the healing process. Tom will return home, and as soon as possible start the rehabilitation necessary to improve the range of motion of the left shoulder."
It is thought that Boonen will take three to six weeks to recover fully, which has ruled him out of this year's Spring Classics.
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