You heard a pop. Now what?

The anterior cruciate ligament, the ACL, is one of the four main ligaments that hold your knee together. It runs diagonally through the middle of the joint, connecting the femur to the tibia, and its job is to keep the tibia (your shinbone) from sliding forward and the knee from rotating out of place when you pivot, plant, or land from a jump.

Most ACL tears happen in a split second. A soccer player plants a foot and twists. A skier catches an edge. A basketball player lands awkwardly from a rebound. There's often a popping sound or sensation, followed by swelling within a few hours and a knee that suddenly feels unreliable, like it can't be trusted on stairs, slopes, or quick changes of direction.

The injury falls on a spectrum. Partial tears leave some of the ligament intact and may stabilize with rehab. Complete tears, the more common scenario, don't heal on their own, because the ACL lives in a fluid-filled joint that prevents the kind of clotting that heals other ligaments. Whether a complete tear needs surgery is a separate question, and it depends entirely on what you want to do with the knee.

At LAOSS, our sports-medicine surgeons treat ACL injuries every week. We don't push surgery on patients who don't need it, and we don't undertreat athletes who do. The conversation starts with an exam, an MRI when warranted, and an honest look at your goals.

Most ACL tears are diagnosed in clinic, not on a scan. The story is often unmistakable (a pivot, a pop, a swollen knee), and a careful exam confirms it. We use specific maneuvers like the Lachman test, anterior drawer, and pivot shift to feel directly for the laxity that a torn ACL produces. In experienced hands, these tests are remarkably accurate.

We then confirm with imaging. Weight-bearing X-rays rule out fracture and tell us about the bones. MRI shows the ligament itself, plus the menisci, cartilage, and bone bruise pattern that often comes with an ACL injury. About half of ACL tears come with a meniscus injury, and many show bone bruising on the femur and tibia where the bones collided as the ligament gave way, both of which change the treatment plan.

Your first visit at LAOSS is built to give you answers, not a maze of referrals. Most ACL patients leave with a confirmed working diagnosis, an MRI scheduled within the week, and a clear next step: whether that's a surgical consult or a structured rehab plan with your in-network physical therapist.

ACL reconstruction is a sports-medicine subspecialty, and our team treats it that way. The surgeons listed below operate on ACLs every week, trained in the same fellowships that produced the team physicians for major professional and collegiate programs, and follow their patients personally from the first visit through full return to sport. You don't get handed off to a different doctor for each step.