There are mixed emotions for the former Qantas Joey following the surgery to repair his ruptured left anterior cruciate ligament (ACL), which he suffered during the Reds' recent National Youth League match against Melbourne Victory.

On the downside, the 17 year-old is almost certain to miss the remainder of the A-League season. However, on the upside his recovery time is expected to be significantly shorter than the standard 12 months normally required to come back from a knee reconstruction.

The tear in Costa's ACL allowed him to have a synthetic graft inserted, meaning a quicker than normal recovery time for a knee reconstruction.

"He had a full knee reconstruction but they used a synthetic fibre instead of an actual graft which can shorten the rehab time. So depending on how his rehab goes, he could be back sooner," Adelaide United Director of Football Michael Petrillo said.

 "The arthroscopy showed that the tear would take a fibre graft. He got out of hospital pretty quickly and the surgeon said the operation went really well and now it's just a matter of getting him into rehab as soon as possible."

Adelaide United Doctor James Ilic said it was a bonus that Costa was able to use an artificial ligament.

"Not everyone is suitable for an artificial ligament but Joe was. It offers a chance to come back much earlier, probably between 4-6 months which is half the normal rehab time so that's a huge plus," Ilic said.

"How successful it will be we won't be able to tell until he's done all his rehab and starts playing again."

Initially shattered by the setback, Costa is driven to come back stronger and he says he will use teammate Lucas Pantelis, who had a knee reconstruction and missed the 2006/07 season, as inspiration and a support during his rehabilitation.

"Of course it's disappointing when you get an injury but you've just got to take the positives out of it and get the recovery right and hopefully I'll be back soon," Costa said.

"You know what they say, 'what doesn't kill you makes you stronger', so I'm definitely going to be determined to come back.

"I've already spoken to Lucas (Pantelis) a bit. He said I can speak to him whenever I want some advice or help on how to recover and deal with it all, so I'll definitely be talking to him, he's a good bloke and I'm sure he'll help me through it."

Costa will go onto the club's long term injury list, and Petrillo says the club is on the lookout for a replacement but would not be rushed into any decision.

Petrillo added: "We're looking at bringing someone in to replace him, we just want to make sure it's worthwhile.

"We're looking right around Australia for an under 23 player and if we can find someone who we think is good enough and will play, because we don't just want them making up the numbers, then we'll do it."