The scrum half was injured in the act of scoring a try for Ulster during last Saturday's RaboDirect PRO12 match against Connacht at the Sportsground.
He joins long-term absentees Jared Payne, Simon Danielli, Chris Cochrane and Tim Barker on the sidelines.
Leinster have already ensured top seeding and a home semi-final in the league play-offs. They have suffered just one reversal in any competition since September, a 23-22 loss to the Ospreys last month.
A Leinster win would ensure a first clean sweep by an Irish province in a season - winning all six interprovincial clashes.
Ulster's defeat at Connacht ended a four-game winning run for them in the RaboDirect PRO12, but Brian McLaughlin's men remain just one point outside the top four going into the final two rounds of action.
They have another trip to Munster on the horizon in the crucial final round of the regular season.
Having lost just once in their last 20 home outings - against Benetton Treviso back in October - McLaughlin will be hoping his side can maintain that sort of form to challenge for a semi-final spot.
Over 9,500 tickets have been sold for Friday's interpro encounter. They are still available for the Promenade and Grandstand and can be purchased online at www.ulsterrugby.com or by calling 02890493222 (option 2).
Due to the high volume of sales, it is likely that only tickets for the Memorial and Aquinas end (behind the posts) will be available to purchase at the gate on match night.
ULSTER Squad (v Leinster) - Backs (16): Blane McIlroy, Ruan Pienaar, Ian Porter, Ian Humphreys, Paddy Jackson, Paddy Wallace, Ian Whitten, Darren Cave, Luke Marshall, Nevin Spence, Michael Allen, Stefan Terblanche, Craig Gilroy, Conor Gaston, Andrew Trimble, Adam D'Arcy.
Forwards (20): Callum Black, Tom Court, Declan Fitzpatrick, Adam Macklin, Paddy McAllister, Andi Kyriacou, Nigel Brady, Rory Best, Lewis Stevenson, Johann Muller (capt), Dan Tuohy, Iain Henderson, Neil McComb, Stephen Ferris, Willie Faloon, Pedrie Wannenburg, Ali Birch, Mike McComish, Chris Henry, Robbie Diack.