ACL Tear: Symptoms, Diagnosis & Treatment
An ACL tear is one of the most common — and most serious — knee injuries an active person can sustain. It usually happens fast: a sudden pivot, a hard landing, a tackle, a non-contact twist where the foot stays planted and the body rotates the other way. There's often a loud "pop," the knee gives out, and within hours the joint swells. At Aptiva Health, our sports orthopedic surgeons diagnose and treat ACL tears every week — for high school athletes, college players, weekend warriors, masters competitors, and patients of every age who want to get back to the sports and activities they love.
Medically reviewed by J. Steve Smith, MD - May 2026.
What is an ACL Tear?
The anterior cruciate ligament — the ACL — is one of four major ligaments that stabilize the knee. It runs diagonally through the middle of the joint, connecting the femur (thighbone) to the tibia (shinbone), and its job is to keep the knee from sliding forward or rotating out of place during movement.
When the ACL tears, the knee loses that stabilizing tether. Most patients describe feeling or hearing a pop at the moment of injury, followed by swelling within a few hours and a sense that the knee "isn't right" — that it shifts, gives out, or can't be trusted on a pivot or a stair.
ACL tears do not heal on their own. The ligament has a poor blood supply, and a complete tear leaves the two ends of the ligament unable to reconnect. In active patients, the standard of care is ACL reconstruction surgery — replacing the torn ligament with a graft that the body rebuilds into a new, functional ACL over four to six months.
Type of ACL Tears
ACL injuries are classified by the severity of damage to the ligament:
Grade I Sprain — The ligament is stretched but still intact. The knee remains stable. These rarely require surgery and usually respond to bracing, rest, and physical therapy.
Grade II Sprain (Partial Tear) — Some of the ligament fibers have torn. The knee is moderately unstable. Depending on the patient's age, activity level, and which fibers tore, treatment may be non-surgical or surgical.
Grade III Sprain (Complete Tear) — The ligament is fully ruptured. The knee is unstable, and the patient cannot reliably cut, pivot, or land. The vast majority of ACL tears are Grade III complete tears. Surgery is typically recommended for any patient who wants to return to sports, work that requires agility, or an active lifestyle.
Symptoms of an ACL Tear
If you've recently injured your knee, an ACL tear is likely if you experienced any of the following:
A "pop" at the moment of injury. Most patients hear or feel a distinct pop. About 50% of ACL tears are accompanied by an audible pop loud enough that other people nearby can hear it.
Sudden knee swelling within hours. Significant swelling within the first 6–24 hours is a hallmark of an ACL tear, caused by bleeding inside the joint (hemarthrosis).
Inability to continue the activity. Most patients cannot return to their game, practice, run, or activity. The knee feels unstable or unsafe to put weight on.
A feeling that the knee is "giving out." Even days or weeks after the initial injury, the knee buckles or shifts unexpectedly during walking, stairs, or pivots.
Loss of full range of motion. The knee may feel stiff, locked, or unable to fully straighten or bend.
Pain along the joint line and deep inside the knee. Tenderness is usually inside the joint rather than along the kneecap or below the knee.
Discomfort walking on uneven surfaces. Patients often describe stairs, hills, and grass as feeling unsafe.
How an ACL Tear Happens
The ACL can tear in several common ways. About 70% of ACL tears are non-contact injuries — they happen without anyone touching the knee:
Changing direction rapidly (cutting, pivoting)
Landing awkwardly from a jump
Stopping suddenly while running
Twisting with the foot planted (the classic "knee turned one way, foot stayed the other")
Direct contact or collision — football tackles, soccer slide tackles, skiing falls
The sports with the highest ACL injury rates are basketball, soccer, football, skiing, gymnastics, lacrosse, volleyball, and cheerleading.
Female athletes tear their ACLs at 2–8 times the rate of male athletes in the same sports. Several factors contribute: differences in hip-to-knee alignment, neuromuscular control, hamstring-to-quadriceps strength ratio, and the way the ACL behaves under hormonal cycles. Targeted neuromuscular training programs can cut female ACL injury risk significantly, and Aptiva's sports medicine and physical therapy teams provide ACL injury prevention training for athletes and teams.
How an ACL Tear Is Diagnosed
At Aptiva Health, an ACL tear diagnosis usually takes a single visit:
History. Your surgeon will ask about the mechanism of injury — what you were doing, whether you felt a pop, how quickly the knee swelled, and whether the knee has felt unstable since.
Physical examination. Specific tests — the Lachman test, the anterior drawer test, and the pivot-shift test — are highly accurate for identifying an ACL tear, often within minutes.
Imaging. An MRI confirms the diagnosis, shows the location of the tear, and identifies associated injuries (the meniscus, the cartilage, the MCL, or bone bruising) that are present in roughly half of ACL tears. Aptiva Health operates its own MRI imaging centers, so most patients can get same-week MRI scheduling without the multi-week wait that hospital-based imaging typically requires.
Treatment plan. After the exam and imaging, your surgeon will walk you through the diagnosis, the associated injuries, the surgical and non-surgical options, and the recovery timeline. You leave the visit with a written plan.
Treatment for an ACL Tear
ACL tear treatment depends on the patient's age, activity level, sport, work demands, and whether other knee structures (meniscus, cartilage, other ligaments) are also injured.
Non-surgical treatment
A complete ACL tear will not heal on its own, but some patients — typically older, lower-activity, or unwilling to undergo surgery — can manage a torn ACL with bracing, physical therapy, activity modification, and quad/hamstring strengthening. This approach trades knee stability for avoidance of surgery, and it works best for patients who don't need to cut, pivot, or land at speed.
Surgical treatment: ACL reconstruction
For the majority of patients — anyone who wants to return to sports, agility-based work, or an active lifestyle — the standard of care is ACL reconstruction surgery. The torn ligament is replaced with a graft (most often the patient's own patellar tendon, hamstring tendon, or quadriceps tendon; sometimes a cadaver allograft), and the new ligament is anchored in tunnels drilled into the femur and tibia. Over four to six months, the body remodels the graft into a functional ACL.
Learn more about ACL reconstruction surgery →
What if other parts of the knee are also injured?
Roughly half of ACL tears come with a meniscus tear, cartilage injury, MCL sprain, or bone bruise. Aptiva's sports orthopedic surgeons routinely address these in the same operation as the ACL reconstruction — repairing the meniscus, smoothing or restoring damaged cartilage, and managing concurrent ligament injuries — so the patient heals from one surgery rather than several.
When to See a Doctor
You should be evaluated by a sports orthopedic surgeon promptly — within days, not weeks — if you experienced any of the following:
A "pop" in your knee during sports or a fall, followed by swelling
Inability to bear weight on the knee
A feeling that the knee is unstable or "gives out"
Swelling that won't resolve
Significant pain inside the knee with movement
Delaying evaluation can let secondary injuries worsen — particularly meniscus tears, which become harder to repair the longer they go untreated. Aptiva Health offers same-day and next-day evaluations for new knee injuries; in many cases, a patient can be seen, examined, scheduled for MRI, and walking out with a treatment plan within 48 hours of the injury.
Schedule your appointment today!
Meet Our ACL Surgeons
Aptiva Health's ACL care is led by three fellowship-trained sports orthopedic surgeons. All three are board-certified, all three perform ACL reconstructions weekly, and all three have built their careers around getting athletes back to the sports they love.
J. Steven Smith, MD Director of Orthopedics
Kerlan-Jobe fellowship-trained — the program where Tommy John surgery was pioneered. Former assistant team physician for the LA Dodgers, Lakers, Kings, and Angels. Now team physician for Ballard, North Oldham, and Anderson County High Schools.
Timothy Wilson, MD - Sports Orthopedic Surgeon
University of Kentucky sports medicine fellowship-trained. Former University of Kentucky Athletics team physician. Published peer-reviewed research on ACL surgery in the American Journal of Sports Medicine and Arthroscopy. 20+ years of practice in Central Kentucky.
Philip Stickney, MD - Orthopedic Surgeon
Dr. D. Philip Stickney, MD, a board -certified orthopedic surgeon, has been providing general orthopedic care for over 25 years. He received his medical degree from Case Western Reserve University in Cleveland, Ohio with orthopedic surgery training at Mt. Sinai in Cleveland and Akron General Medical Center in Akron, Ohio. He treats a variety of conditions from arthritis to sports medicine and occupational injuries.
ACL Tear Treatment Across Kentucky and Indiana
Louisville Metro
Concussion & Sports Medicine Institute — 3611 Newburg Road, Louisville, KY 40218. Tel: (502) 909-0772
Louisville – Central — 3615 Newburg Road, Louisville, KY 40218. Tel: (502) 909-0772
Louisville - Downtown — 300 S 13th Street, Louisville, KY 40203. Tel: (502) 583-1011
Louisville - East — 10100 Linn Station Road, Suite 1A, Louisville, KY 40223. Tel: (502) 909-0772
Louisville - Middletown — 401 N English Station Road, Suite 1A, Louisville, KY 40223. Tel: (502) 909-0772
Mt. Washington — 737 N Hwy 31E Bypass, Ste 2, Mt. Washington, KY 40047. Tel: (502) 909-0772
Central Kentucky
Lexington — 230 Fountain Court, Suite 180, Lexington, KY 40509. Tel: (859) 592-1008
Lexington Imaging Center — 426 Codell Drive, Lexington, KY 40509 (859) 592-1008
Lexington Physical Therapy — 152 W Tiverton Way, Suite 180, Louisville, KY 40503. Tel: (859) 592-1008
Southern Kentucky
Elizabethtown — 529 Westport Road, Ste 2, Elizabethtown, KY 42701. Tel: (270) 506-4888
Northern Kentucky / Greater Cincinnati
Northern Kentucky — 2093 Medical Arts Drive, Hebron, KY 41048. Tel: (859) 592-1008. serving Hebron, Florence, Covington, Newport, and the Cincinnati DMA
Indianapolis
Indianapolis — 6801 Gray Road, Indianapolis, IN 46237. Tel: (463) 303-0501.
The Aptiva Health Difference
ACL care at Aptiva Health is built around one principle: the fastest pathway from injured to back-to-sport, without bouncing between offices. Because Aptiva houses sports orthopedic surgery, MRI imaging, physical therapy, pain management, and immediate injury care under one organization, a patient who tears an ACL on Saturday can be seen Monday, scanned Wednesday, scheduled for surgery the following week, and rehabbed in-network by a physical therapist who already has their imaging and surgical notes. Three sports orthopedic surgeons, six locations, one care pathway.
Frequently Asked Questions
How do I know if I tore my ACL?
The strongest signs of an ACL tear are a "pop" at the moment of injury, significant knee swelling within 6–24 hours, inability to continue the activity, and a feeling that the knee is unstable or "gives out." Definitive diagnosis requires a physical exam by a sports orthopedic surgeon and an MRI.
Can you walk on a torn ACL?
Many patients can walk on a torn ACL once the initial swelling subsides — the ACL is a stabilizer, not a weight-bearing structure. However, the knee will feel unstable on pivots, cuts, stairs, and uneven surfaces, and walking on a torn ACL increases the risk of secondary damage to the meniscus and cartilage. A torn ACL should be evaluated promptly.
What's the difference between an ACL tear and an ACL sprain?
"ACL sprain" and "ACL tear" are graded on the same scale. A Grade I sprain is a stretched but intact ligament. A Grade II sprain is a partial tear. A Grade III sprain is a complete tear — what most people mean by "torn ACL." About 90% of ACL injuries in athletes are complete (Grade III) tears.
Does an ACL tear require surgery?
A complete ACL tear will not heal on its own. Patients who want to return to sports, agility-based work, or an active lifestyle typically need surgery. Older, lower-activity patients can sometimes manage a torn ACL non-surgically with bracing and physical therapy. The right choice depends on age, activity level, and the patient's goals.
How long does ACL recovery take?
Most patients are cleared to return to running at 4–6 months after surgery, sport-specific training at 6–9 months, and competitive play at 9–12 months. Aptiva's surgeons use functional return-to-sport testing — strength, balance, and movement quality — rather than pure timeline benchmarks before clearing a patient back to full play.
What kind of MRI do I need for a suspected ACL tear?
A standard 1.5T of the knee, without contrast, is the standard of care for diagnosing an ACL tear. Aptiva Health operates its own MRI imaging centers and offers same-week scheduling — significantly faster than most hospital-based imaging.
Are women more likely to tear their ACL than men?
Yes. Female athletes tear their ACLs at 2–8 times the rate of male athletes in the same sports. The reasons include differences in hip-to-knee alignment, neuromuscular control, and hamstring-to-quadriceps strength ratio. Targeted neuromuscular training programs can significantly reduce this risk.
What if my ACL tear also damaged my meniscus or cartilage?
Roughly half of ACL tears come with a meniscus tear, cartilage injury, or other ligament damage. Aptiva's sports orthopedic surgeons address these in the same operation as the ACL reconstruction so the patient heals from one surgery rather than several.
Does Aptiva Health treat ACL tears in children and teenagers?
Yes. ACL tears in skeletally immature patients require specialized surgical techniques that protect the growth plates. Aptiva's sports orthopedic surgeons treat ACL tears in middle school, high school, and college-age athletes regularly.
What does an ACL tear evaluation cost?
Aptiva Health accepts most major medical insurance plans, Medicare, Medicare Advantage, most Medicaid plans, workers' compensation, auto accident coverage (PIP and MedPay), and cash-pay arrangements. Your office team can verify benefits before your visit.
Can I see an Aptiva ACL surgeon for a second opinion?
Yes. Many ACL patients come to Aptiva for a second opinion before deciding on surgery. Bringing your prior imaging (MRI, X-ray) and any prior physician notes makes the consultation most useful.
