The Dallas Mavericks’ rather bizarre season just got worse. A whole lot worse. As in lose their star-point-guard-to-an-anterior -cruciate-ligament-injury worse. In a season where they’ve seen their center Dereck Lively II go down with a broken foot, traded their five-time All-NBA playmaker star, Luka Dončić, to the Los Angeles Lakers for an older Anthony Davis and then had Davis go down with an adductor muscle strain, the Mavs will now have to make do without their All-Star point guard Kyrie Irving. Irving tore his left ACL in the first quarter of Monday’s loss to the Sacramento Kings. That means what was their remaining best player is out for the season and the Mavs chances of making it back to the NBA Championships after doing so last year just went from bad to worse.

If you Google, “what’s the worst injury a basketball player can suffer,” those three letters, ACL, come up often. That’s because the ACL plays a big role in keeping the knee stable. And you kind of need your knee stable when you play basketball with all the running, cutting and jumping the sport requires. Plus, full recovery from ACL reconstruction surgery can take at least a year and is not always guaranteed. Chicago Bulls guard Derrick Rose, for example, did lose a fair amount of his trademark explosiveness after he tore his left ACL during his third season in the NBA.

The ACL has the word cruciate in the middle of it because it forms a criss-cross or X with the posterior cruciate ligament. And X marks the spot here in keeping your knee stable. Both ligaments connect your upper leg bone, known as the femur, with the bigger lower leg bone, known as the tibia, as I have written before for Forbes.

A ligament is a band of fibrous tissue that connects one bone to another bone. Now, there are additional ligaments running along the sides of your knees to connect the femur and tibia. So it’s not as if your lower leg would completely fall off if you were to completely tear both the ACL and the PCL. But a complete tear of either cruciate ligament could be crucial and mean that your knee joint goes a rocking in bad way.

A doctor can get a sense if you’ve torn your ACL by checking the stability of your knee and seeing how much your lower leg moves when pulled. This includes checking for something called an anterior drawer sign. But to confirm an ACL tear and the degree of the tear, you typically need to undergo an MRI.

A partial tear of the ACL may not need surgical repair if the knee remains relatively stable. The same may be true with a complete tear if most of the cutting that you’ll do is limited to your hair with a pari of scissors. However, someone who plays competitive basketball like Irving typically will need to get a completely torn ACL reconstructed.

An ACL reconstruction involves creating a new ACL since such ligaments don’t tend to grow on their own. This can consist of harvesting a tendon from another part of your body, most often part of your patella tendon or your hamstring tendons, specifically the gracilis and semitendinosus tendons. When the tissue comes from your own body, it’s called an autograft, because you are creating a graft from yourself.

Alternatively, you can get an allograft, which is when the tissue comes from someone else. This can be an ACL from a cadaver. Since you aren’t snipping off tissue from other parts of your body, you will likely recover faster from an allograft ACL reconstruction than an autograft. However, allografts can be less durable and in some cases, your body and immune system could effectively say, “Oh, hell no,” and end up rejecting the foreign tissue.

Surgery will only be the first chapter in Irving’s recovery from the ACL tear. Months of rather intense rehab will follow. The muscles around the knee shrink tend to shut down and shrink with startling rapidity once all that inflammation build up around a torn ACL. Therefore, you’ve got to go through lots of physical therapy to get those muscles built up and strong again. Plus, your knee after such a serious injury can be a bit like that lead character Matt Damon played in The Bourne Ultimatum. It can quickly forget how it is supposed to work and function. It can even lose proprioception, which it’s ability to know where it is in space. It can take months to completely retrain the knee to do all that it is supposed to do.

Therefore, it can take months for you to return to all your regular daily activities. And again if your daily activities consist dribbling and shooting a basketball and getting past other top athletes, you may need at least six months to get back on the court. Even after you do get back to playing basketball in some way, don’t expect to immediately be the same full throttle player you may have been. You and your knee will still have to re-learn a lot. Plus, it will be natural to be rather unsure about your newly reconstructed knee. It can be at least a year or two before you stop worrying about your knee and feel whole again.

The Mavs did tweet, or X or whatever they’re called these days, that “We know you’ll come back stronger than ever,” followed by thumbs up and infinity sign emojis:

One emoji that should accompany any ACL injury and reconstruction for any elite athlete is a question mark. While surgery and physical therapy techniques have gotten better over the years, you never know how much quickness, agility and cutting ability will be lost. Irving’s game including his legendary crossover dribble has heavily relied on such athleticism. If he does suffer a dip as Rose did, a big question will be how Irving adjusts his game accordingly.

At 32 years of age, Irving is also already around the age when NBA players’ athleticism in many cases starts to decline. An analysis of ESPN data has suggested that NBA players are at the prime from 27 to 31 years of age. Of course, Irving is not your typical NBA player. But even a guy named Michael Jordan had the adapt his game when he reached his mid-30s.

Moreover, it can get harder to recover from major injuries and surgery, the older you get. When you are in your 20s, you can seemingly do all sorts of things to your body with little consequence, like eating an entire pizza for breakfast and go running right afterwards. Therefore, one could expect the recovery of someone in his 30s to be a little more challenging than those in their 20s, although Rose was only 23 when he suffered his ACL tear.

Another question is how much Irving’s increased workload following the Dončić trade contributed to his tearing his ACL. The game against the Kings came after a 10-game stretch in which Irving had averaged 39.3 minutes of playing time a game. That average topped all NBA players from February 4 to March 2. Again, that’s a 32-year-old playing more minutes per game than a whole lot of 20 somethings.

It can be difficult to tell whether a given ACL tear resulted from a single unfortunate twist of the knee independent of what happened prior or instead was the ligament finally giving out after being weakened over time. There’s also the possibility that when you get fatigued, your muscles may not be as able to fully support your knee and your footwork can get sloppier, making the possibility of an awkward twist all the more likely.

What is certain is that the Mavs will miss Irving’s average of 24.7 points, 4.8 rebounds and 4.6 assists this season. Only time can tell if he can get back to those levels in the next 2025-26 season. There’s no denying that this is a big blow for both the Mavericks and Irving. In fact in a live stream on Tuesday, Irving did say "It does suck. A lot. I ain’t going to lie to you guys. This one stings for sure," as you can see here:

At the same time, Irving apparently didn’t want fans to shed too many tears for his tear when he said, "Just wanted to let you guys know that I’m OK and I will be OK moving forward." Keep in mind that Rose did go on to have a highly productive NBA career after his ACL reconstruction. A number of other players have come back from similar injuries strong or in some cases stronger than ever such as Al Harrington, Al Jefferson, Baron Davis, Jamal Crawford, Corey Brewer and Bonzi Wells.

The stars haven’t been aligning for the Mavericks this season just a year after they made it all the way to finals. In fact, they can’t even seem to keep stars like Kyrie Irving on the court.