Kristaps Porzingis' ACL surgery is complete. The New York Knicks' star forward had his procedure Tuesday at the Hospital for Special Surgery in Manhattan.

So when will Porzingis return to the court? That's unclear.

The expectation, at this point, is that Porzingis will be out for at least 10 months, sources tell ESPN. But a more specific timetable won’t be available until Porzingis begins rehab.

What will that rehabilitation process look like? And will Porzingis be able to return to his pre-injury form?

To provide some answers, we turned to ESPN injury expert Stephania Bell. Below, Bell provides insight on those topics and others related to Porzingis' recovery. (Bell, to be clear, is speaking from a general perspective with regards to Porzingis’ type of injury; she is not speaking specifically of Porzingis’ situation because she has not treated him).

Kristaps Porzingis had ACL surgery Tuesday at the Hospital for Special Surgery in Manhattan. Ned Dishman/NBAE via Getty Images

What could Porzingis' potential timeline for recovery look like?

Bell: "On average, NBA athletes return to play in the range of 10-12 months following ACL reconstruction. It’s important to note that the specifics of the injury including, most importantly, whether it’s an isolated [ACL-only] injury or not [meaning multiple structures involved such as meniscus, cartilage, or other ligaments] will dictate the complexity of the surgery and the complexity and pace of rehab. (Note: Porzingis’ injury is believed to be ACL-only.) The more there is to address in surgery, the more complex the rehab. Depending on the details of the surgery, the rehab process can be deliberately slowed at certain points to protect tissues that are still healing even if the player feels he is progressing well.

"There are other factors that can potentially influence the rehab process including the athlete’s ability to heal, his adherence to the rehab program, prior injury, anatomical variants, muscular imbalances or strength deficits, neuromuscular control. There are also the specific demands of the position, the athlete’s role on the team and so on. When you start to consider all the different factors that have the potential to influence an athlete’s recovery, it becomes easier to appreciate the reluctance for an organization to issue a firm timetable based on a diagnosis alone."

Could this injury impact Porzingis’ athleticism at all?

Bell: "Sure ... if he attempts to return before he is truly ready to return. Part of rehabbing completely from an injury like this is going beyond the basic ability of performing basketball activities to actually returning to prior level of function. That also doesn’t necessarily mean that an athlete looks like his pre-injury self the first time he steps on the court. Return to play is often referred to as the final phase of rehab because there is no substitute for on-the-floor competition at the highest level. Most athletes will say that they don’t truly feel like they’re back to their pre-injury performance level until six months to a year after they’ve returned to action.

"They can still be effective in the statistics department, however, even as they return to form. In a study published in 2013 looking at return-to-play rates and performance of NBA players following ACL reconstruction, various performance metrics [points, rebounds, blocks, etc.] declined in players returning from this injury. But, that decline did not differ significantly from controls (no ACL tear)."

Is the injury or the recovery process different -- or more difficult -- because of Porzingis' 7-foot-3 height?

Bell: “There isn’t enough specific data on NBA big men compared to other NBA players to provide evidence here but, anecdotally, their recovery appears to be a bit slower. The question then becomes why. Smaller, more nimble players have a higher demand in the quick-cut, pivot and agility area and have to focus rehab on this skill set prior to return. Larger players may be more challenged in terms of retraining dynamic muscular control that helps protect the knee.

"The long levers of the thigh and the lower leg meet at the knee and, if not well controlled by the muscles above [the hip] and below [the ankle], the resultant forces can threaten the least forgiving joint -- the knee -- in the middle. Interestingly, in the case of Porzingis, when he lost control at his ankle (as he landed on Giannis Antetokounmpo's foot), his hip could not prevent his knee from buckling and the result was an ACL tear.

"Even prior to this injury, there may have been some hints he would be at risk. Porzingis sprained his left ankle in early November. In December -- and again in January -- he was dealing with soreness in his left knee. Related? There is no way to know for sure but it certainly suggests he will have work to do to strengthen from top to bottom before he returns to action. Otherwise, he will be at increased risk for re-injury. Given that he is a young player with a promising future, Porzingis would be better served with a methodical and comprehensive rehab process addressing any global weaknesses rather than trying to meet an artificial timeline.”

The road ahead will be a long and difficult one for Porzingis. At the time of his injury, the 22-year-old All Star led the Knicks in scoring (22.7 points per game) and led the NBA in blocks per game (2.4). Just how the ACL injury will impact Porzingis' numbers going forward is unclear, but ESPN’s Kevin Pelton provided strong historical context on how ACL injuries have impacted players between ages 21-23 here. That data suggests that Porzingis’ numbers may lag for two seasons following his return. But every player's injury -- and ability to recover -- is different.

And those closest to Porzingis believe his diligent approach to rehab will help him return to the court a better player.

“He has a great attitude about it. He knows he’s going to get back,” Knicks coach Jeff Hornacek said Monday. “He knows he’s going to be back better than ever. He wishes it didn’t happen that way, but he’ll able to learn things from watching the game the rest of this year. He’s a kid who wants to be one of the best. We know he’s going to work hard to get back.”