Sexson suffered a subluxation of the shoulder and a bruised humeral head, but team officials were not sure how long the 29-year-old slugger will be sidelined.
"This is an unusual injury in that the bruise is in the back of the humerus, thus it may be an injury that we can treat and hopefully get him back on the field in a timely manner," team physician Dr. Michael Lee said.
Sexson will begin rehabilitation immediately.
In his first season with the Diamondbacks, Sexson is hitting just .241. But he is tied for second in the National League with nine home runs and second in the majors with 22 RBI.