ST. LOUIS -- The St. Louis Rams have lost two defensive stalwarts for the rest of the season, with end Robert Quinn to undergo back surgery and safety T.J. McDonald headed for a shoulder procedure.

Coach Jeff Fisher said Wednesday both players will be placed on injured reserve.

St. Louis' pass rush hasn't been the same without Quinn, who has missed three straight games and four of the last five with hip and back injuries.

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McDonald was sidelined late in Sunday's 27-3 loss to Arizona.

Tight end Lance Kendricks was limited while clearing the concussion protocol but cornerback Janoris Jenkins, who also sustained a concussion on Sunday, did not practice.