But the recovery took two months.
"It's certainly been a bit longer than I wanted it to," said O'Brien. "As the weeks went by, I stopped putting a target on what game I would be actually back for."
O'Brien, who felt like the had been "shot in the leg" when hurt in early June, is expected to make his return to the Vancouver lineup Saturday when the Whitecaps host the San Jose Earthquakes. The 34-year-old Harrogate, England native has missed nine games after he expected to miss just one.
"It's good now being able to talk to you about, maybe, being available for the first team," said O'Brien following a practice Friday.
O'Brien's return is timely because fellow central defender Brad Rusin is slated to miss the game with an ankle injury. Rusin, injured last weekend in a 1-1 tie at Portland, is out for the third time this season.
The 26-year-old Crown Point, Ind., native's absence adds to the ongoing woes of a back line that has battled injuries all season long.
O'Brien, who signed a one-year contract extension this week, appears unlikely to start. But he could see some minutes off the bench as he eases his way back into action while the Whitecaps prepare for the stretch drive of the season.
"He's been out for longer than we thought, and he's a very important player for us," said Vancouver coach Martin Rennie. "He brings a lot of experience and leadership, so it's nice to have him back."
Prior to joining the Whitecaps, O'Brien, who has overcome a public battle with depression, made nearly 500 appearances with English clubs including Premier League sides Bradford, Newcastle, Portsmouth and Bolton.
The dual British-Irish citizen also played in the UEFA Champions League with Newcastle United and was a member of the Republic of Ireland's 2002 FIFA World Cup squad.
He will provide a calming presence to a club that has seen its string of success start to unravel lately. The Whitecaps have only one point — from the key draw against Portland — in the last three games after going unbeaten in six.
Heading into this weekend's play, the Whitecaps (9-7-6) sit tied for fourth place in the Western Conference but the Earthquakes (8-9-6) can pull even with Vancouver with a victory.
Despite their low position, the Earthquakes are not languishing. San Jose has won three games in a row, posting two clean sheets in the process, and finds itself only three points back of the Whitecaps.
The Earthquakes have turned their season around since Vancouver native Mark Watson, a former Canadian national team player with 78 international caps, was appointed interim coach.
Watson was elevated from his assistant's post, a position he has also held with Canada's national men's team. He replaced former coach Frank Yallop, another Vancouverite and former Canadian coach, who parted ways with San Jose in June.
Rennie is not putting emphasis on the game's significance in the standings.
"Looking at the table isn't that important," said Rennie. "What's really important is how we play and how we go about our job. … You could win three in a row and still be in the same position if other teams win."
Meanwhile, Whitecaps goalkeeper David Ousted will make his second consecutive start after seeing his first action with the club last weekend in Portland.
"I'm looking forward to coming into B.C. Place and meeting the fans and having my first home game," he said.
Ousted, a former Danish Superliga star who signed with the Whitecaps in late June, will be counted on to help the Whitecaps maintain their strong record at home, where they are 7-1-3 this season. One opponent who could test him is striker Chris Wondolowski, who has seven goals in six career games against the Whitecaps.
Wondolowski, the league's most valuable player in 2012, scored two goals for San Jose last week against Chivas USA after missing a month while he was away playing for the American side that won the CONCACAF Gold Cup. The 31-year-old Danville, Calif., native led the U.S. with five goals.
While he attempts to maintain his good form, Ousted hopes a strong home effort will help him earn more starts.
"It's important to get into a run of games and get in there and be comfortable with the back four and with the team," said the 28-year-old native of Greve, Denmark.
"It's been good for me getting to know the guys, and I hope to play a lot of games from now on."
Notes: Whitecaps midfielder Jun Marques Davidson is eligible to return after serving a one-game suspension for head-butting a Philadelphia player July 27, while fellow Caps midfielder Gershon Koffie will return after serving a one-game ban for yellow-card accumulation. … Vancouver's Nigel Reo-Coker and San Jose's Steven Lenhart face an automatic one-game suspension for their next yellow cards. … Vancouver's Darren Mattocks continues to recuperate from arthroscopic knee surgery, but has yet to resume training with the team. Fellow striker Kenny Miller will return after missing last weekend's game with a groin injury. ... San Jose defender Ty Harden (hip) and Peter McGlynn (undisclosed) are out with injuries.