Anterior Cruciate Ligament
The anterior cruciate ligament is one of the main stabilizing bands inside the knee. It connects the thigh bone to the shin bone and keeps the shin bone from sliding forward. It also helps control twisting movements of the knee. An ACL injury can happen during sports, motor vehicle accidents, or even daily activities when the knee is twisted or stretched too far.
How Common It Is and Who Gets It? (Epidemiology)
ACL tears are common in people who play sports that involve cutting, sudden stops, or jumping. These injuries affect active young adults the most, but they can occur at any age. Both athletes and non-athletes can experience an ACL tear.
Why It Happens – Causes (Etiology and Pathophysiology)
An ACL injury usually happens from a forceful twist or sudden change in direction while the foot is planted. It can also occur from landing incorrectly after a jump, rapid deceleration, or direct contact such as a tackle. The ligament may tear completely or partially depending on the force on the knee.
How the Body Part Normally Works? (Relevant Anatomy)
The ACL sits in the middle of the knee next to the posterior cruciate ligament. It starts at the lower end of the thigh bone and attaches to the upper end of the shin bone. Together with the posterior cruciate ligament, it provides stability during straight-line and rotational movements. The ACL also helps keep the knee from giving way during twisting activities.
What You Might Feel – Symptoms (Clinical Presentation)
Many people feel or hear a “pop” when the ACL tears. The knee often becomes swollen within a few hours. Walking can be painful, and the knee may feel like it might buckle or give out. Some people also develop pain from associated injuries such as meniscus tears or bruising of the bone.
How Doctors Find the Problem? (Diagnosis and Imaging)
A doctor examines the knee to check for swelling and looseness. X-rays help rule out fractures. An MRI shows the ACL and confirms whether the tear is complete or partial. Some patients who cannot have an MRI may be diagnosed during arthroscopic surgery.
Classification
ACL tears can be complete, where the ligament is fully torn, or partial, where some fibers remain attached. A tear may occur near the ligament’s attachment to the bone or in the middle of the ligament. These details help guide treatment.
Other Problems That Can Feel Similar (Differential Diagnosis)
Pain and swelling in the knee may also come from meniscus tears, injuries to the collateral ligaments, or bone bruises. Early swelling and inability to bear weight can also be seen in fractures or severe sprains.
Treatment Options
Non-Surgical Care
Conservative treatment may be recommended for older adults, individuals with low activity demands, patients with arthritis, or those with partial tears. This approach can include bracing, activity modification, and supervised physical therapy. Rehabilitation focuses on restoring motion and strength.
Surgical Care
Surgery may be advised for younger and active patients, those with complete tears, or those whose knee keeps giving way. Two types of surgery are used:
ACL Repair:
Repair may be used when the ligament pulls off from its attachment on the thigh bone. The surgeon reattaches the native ligament using stitches or supportive tapes. This is done through small arthroscopic incisions.
ACL Reconstruction:
Most ACL tears require reconstruction. The torn ligament is replaced with a substitute graft. Graft options include hamstring tendon, quadriceps tendon, patellar tendon, or a donor (allograft) tendon. The choice depends on patient activity, age, and type of injury.
Recovery and What to Expect After Treatment
Surgery is usually done arthroscopically, and patients go home the same day with a brace and crutches. Swelling improves with rest, ice, compression, and elevation. Patients walk carefully with help from crutches for the first day due to the nerve block. Dressings are changed after seventy-two hours, and showers can begin afterward. Follow-up visits adjust the brace and check healing. Most patients begin physical therapy early and continue it for several months. Recovery may take five to eight months or longer, depending on injuries and strength.
Possible Risks or Side Effects (Complications)
Complications can include swelling, bruising, stiffness, infection, blood clots, nerve or vessel injury, graft failure, hardware irritation, donor-site pain, and persistent discomfort. Medical risks relate to anesthesia and overall health, such as allergic reactions, pneumonia, or heart-related problems. Some patients are at higher risk due to smoking, obesity, diabetes, sleep apnea, or previous failed surgeries.
Surgical Complications:
- Infection
- Deep vein thrombosis and its subsequent complications including pulmonary embolism and possible death
- Excessive swelling & Bruising
- Joint stiffness
- Tingling and numbness
- Graft failure
- Damage to nerves or vessels
- Hardware problems
- Donor site problems
- Residual pain
- Reflex Sympathetic Dystrophy
Some of these conditions may require hospitalization, aspiration, injections or even surgery
Certain patient population is at a higher risk for complication which include but are not limited to:
- Previous failed surgeries
- Smoking
- Seizures
- Obstructive sleep apnea
- Obesity
- High blood pressure
- Diabetes
- Other medical conditions involving your heart, lungs or kidneys
- Medications, such as aspirin, that can increase bleeding
- History of heavy alcohol use
- Drug allergies
- History of adverse reactions to anesthesia
Long-Term Outlook (Prognosis)
ACL reconstruction has a long history of good results, especially in younger and active people. ACL repair can work well when patients are properly selected. Physical therapy and patient motivation play major roles in achieving a good outcome. Many patients return to their previous level of activity.
Out-of-Pocket Costs
Medicare
CPT Code 27407 – Anterior Cruciate Ligament Repair: $190.66
CPT Code 29888 – Anterior Cruciate Ligament Reconstruction: $229.85
Medicare typically covers most of the approved charge for these procedures, leaving patients responsible for a twenty percent portion. Supplemental insurance plans such as Medigap, AARP, or Blue Cross Blue Shield usually remove this remaining share, so many patients end up with little to no expense when the surgery is approved under Medicare rules. These supplemental policies work together with Medicare and are meant to close the financial gap that would otherwise remain.
Secondary insurance, including employer plans, TRICARE, or the Veterans Health Administration, may take care of any leftover balance after Medicare and a supplemental plan have paid their shares. Some of these secondary policies have their own deductible, usually between one hundred and three hundred dollars, and that amount may need to be met before they pay. Once that deductible is satisfied, these plans often cover the remaining costs related to the procedure.
Workers’ Compensation
If your anterior cruciate ligament injury happened because of a work-related event, Workers’ Compensation pays for the entire treatment, including surgery, therapy, and follow-up care. This coverage leaves you with no out-of-pocket expenses.
No-Fault Insurance
If the anterior cruciate ligament injury came from an automobile accident, No-Fault Insurance covers the entire cost of treatment. You may only be responsible for a small deductible, depending on your specific policy.
Example
A patient needed surgery for an anterior cruciate ligament injury after a sudden twisting incident. With Medicare, the expected out-of-pocket cost was 229.85 dollars. However, because this patient also had a secondary insurance plan, the remaining balance was paid in full, resulting in zero out-of-pocket expenses.
Frequently Asked Questions (FAQ)
Q. Will my knee make a popping sound when the ACL tears?
A. Many people report a pop at the moment of injury, but not everyone notices it.
Q. How long does recovery take?
A. Most patients recover over five to eight months, but athletes may need longer before returning to sports.
Q. Will I need crutches?
A. Yes, crutches are used at least for the first day due to the nerve block.
Q. Can I drive after surgery?
A. You should avoid driving until you can safely control the vehicle and your doctor says it is allowed.
Q. Will the graft fail?
A. Graft failure can occur, but careful rehabilitation lowers the risk.
Summary and Takeaway
An ACL tear can lead to pain, swelling, and a feeling of the knee giving way. Treatment depends on age, activity, and the type of tear. Non-surgical care may work for some patients, while others benefit from repair or reconstruction surgery. Proper rehabilitation and steady progress help most people return to their usual activities.
Clinical Insight & Recent Findings
A recent study examined how psychological factors shape recovery after anterior cruciate ligament surgery and found that fear of reinjury, low confidence, and limited psychological readiness can slow rehabilitation, alter knee mechanics, and reduce the odds of returning to sport, even when physical strength has improved.
These findings support what many patients experience during the treatment pathway you reviewed: although the ligament injury, diagnosis process, and surgical choices such as anterior cruciate ligament repair or reconstruction focus on restoring knee stability, long-term success also depends on how secure and confident a patient feels during movement, especially when beginning weight bearing, strengthening, and proprioceptive training.
Fear of twisting, pivoting, or returning to high-demand activity can persist even after the graft is strong, and the study shows that targeted strategies such as imagery training, structured physical therapy, and bracing can improve both confidence and functional outcomes.
By integrating these psychological considerations into routine care, patients undergoing anterior cruciate ligament repair or reconstruction may achieve better stability, faster progression through rehabilitation, and safer return to activity. (“Study of psychological recovery after anterior cruciate ligament reconstruction – See PubMed.”)
Who Performs This Treatment? (Specialists and Team Involved)
ACL injuries are treated by orthopedic surgeons who specialize in knee surgery and sports injuries. The care team may also include anesthesiologists, physical therapists, physician assistants, and nurses who assist with recovery.
When to See a Specialist?
A specialist visit is recommended if your knee swells quickly after an injury, feels unstable, or continues to be painful or weak. Early evaluation helps prevent further damage.
WHEN TO CONTACT A DOCTOR’S OFFICE AFTER SURGERY:
- temperature more than 101 degrees Fahrenheit
- increased pain or tenderness near the incision
- poor pain relief
- signs of infection: increased swelling, redness, increased drainage, increased warmth, pus, foul smell, bleeding at the incision, incision coming apart
- inability to feel or move fingers or toes
- pale blue, white or abnormally cold fingers or toes
- nausea (upset stomach) or vomiting (throwing up) that won’t stop
- increased tiredness
- a generally worse feeling than you had when you left the hospital
- problems urinating, severe constipation or severe diarrhea
- a concern about any other symptoms that seem unusual
When to Go to the Emergency Room?
Go to the emergency room if you experience chest pain, trouble breathing, severe allergic reactions, signs of blood clots, heavy bleeding, high fever, or sudden worsening of symptoms after surgery.
WHEN TO VISIT AN EMERGENCY ROOM AFTER A SURGERY:
- Suspected cardiac problem: severe chest pain or pressure, shortness of breath, tightness in chest, pain in left arm, jaw pain, dizziness or fainting, unexplained weakness or fatigue, rapid or irregular pulse, sweating, cool, clammy skin, and/or paleness
- Suspected Stroke: trouble speaking, changes in vision, confusion or other change in mental status
- Suspected venous thrombosis: swelling of the legs, ankles, or feet, discomfort, heaviness, pain, aching, throbbing, itching, or warmth in the legs, sudden shortness of breath, chest pain, coughing up blood, rapid or irregular heart rate
- Suspected Sepsis: high grade fever, with shivers associated with fatigue, dizziness, racing heart, pale or discolored skin, sleepy, difficult to rouse, confused, short of breath
- Heavy bleeding from the surgical site
- Severe allergic reaction with trouble breathing, swelling, hives
What Recovery Really Looks Like?
Recovery involves gradual improvement in swelling, motion, and strength. Patients progress from walking with support to normal daily activities. Returning to sports requires consistent physical therapy and time for the graft to strengthen.
What Happens If You Ignore It?
Ignoring an ACL tear can lead to repeated knee instability, additional injuries to the meniscus or cartilage, and worsening long-term knee function.
How to Prevent It?
Prevention: While ACL injuries can happen suddenly and unexpectedly, there are steps you can take to reduce your risk, including:
- Warm-Up Properly: Always warm up before engaging in physical activity, especially sports. A proper warm-up prepares your muscles and joints for the demands of exercise, reducing the risk of injury.
- Use Proper Technique: Whether you’re running, jumping, or changing direction, using proper technique can help reduce the strain on your knees and lower the risk of injury.
- Strength Training: Incorporate strength training exercises into your workout routine to build strong muscles around your knees, providing added support and stability.
- Wear Protective Gear: If you participate in sports that carry a risk of ACL injury, such as soccer or basketball, wearing appropriate protective gear like knee braces or supportive footwear can help reduce your risk.
- Listen to Your Body: If you experience pain or discomfort during exercise, don’t ignore it. Stop and rest, and consult a healthcare professional if the pain persists.
Nutrition and Bone or Joint Health
Nutritious meals that include lean protein, fruits, vegetables, and adequate hydration help support healing. Many patients benefit from foods that promote healthy tissue recovery.
Activity and Lifestyle Modifications
Return to activity should be gradual. Cycling and swimming are common early exercises. Jogging typically begins around three months. Full sports participation often requires at least six months and depends on strength, confidence, and training.
Do you have more questions?
What is your ACL, and what does it do?
Anterior Cruciate Ligament or the ACL is an important ligament inside the knee. It is present in the middle of the knee, and pairs with another ligament called posterior cruciate ligament, or PCL. Both ligaments help in stability of the knee joint, and prevent the knee from sliding on itself, hence preventing the feeling of buckling, giving way, or falling. In the absence of either one, or both the ligaments, the knee is unstable, and the patient will have difficulty walking, but especially with running, pivoting, and cutting.
What does it feel like to have a torn ACL?
Patients who have a torn ACL usually remember an injury in which they may have fallen or got hit on the knee, with or without hearing or feeling of a pop in the knee joint. These patients have sudden onset of pain associated with swelling. They also have limping because of pain. These patients also have instability and may have episodes of buckling or giving way.
Can an ACL tear heal without a surgery?
In case there is a complete ACL tear, the chances of healing without a surgery are remote. That nevertheless does not preclude conservative treatment as patients with low demands can be treated with physical therapy. If the patient has a partial tear of the ACL then, there is chance that the patient may get better just with physical therapy. If the patient does not got a stable knee even after physical therapy, then they may need ACL surgery.
Is ACL surgery serious?
ACL reconstruction, or repair surgery of the knee, is one of the major arthroscopic surgeries of the knee. It involves inspection of the joint, with repair, or reconstruction of the ACL along with treatment of any associated injury like meniscal tear. The surgery itself may take one and a half to two hours to complete. The rehabilitation process after the surgery is tedious, and involves constant supervision with a physical therapist, and a physician.
Is surgery required for a torn ACL?
If the ACL is torn completely, and the patient is in high demand of work, or recreation, then ACL surgery is preferable to give stability to the knee. If the patient is in low demand work, or has multiple comorbidities, then patients may be treated conservatively. Patients who do not undergo ACL surgery have higher chance of getting injury to other parts of the knee, like the meniscus, and the cartilage.
Can you still walk with a torn ACL?
After the ACL is torn, the knee becomes unstable, which is worsened by strenuous activities, like running, or pivoting, and cutting. Patients can still walk with a torn ACL, and may, or may not, require a brace to stabilize the knee.
How long does it take to recover from a partially torn ACL?
Patients with partially torn ACL are instructed to do all of this, and, have a rehabilitation program with a physical therapist. They may take up to eight to twelve weeks to recover. Some patients may take longer periods depending on the ACL torn. Few patients may even fail rehabilitation protocol, and may have to undergo a reconstruction of ACL, later.
Can you still walk with a torn ligament in your knee?
A torn ligament in the knee does causes instability. If only a single ligament is torn, patient is usually able to walk, though he may have some instability, and may need to use a brace, or crutches for support. If the patient has injury to multiple ligaments, or ligaments and meniscus, it may be difficult for the patient to walk without having a feeling of instability, or giving way, and may have episodes of falling.
Can a partial ACL tear heal on its own?
A partial ACL tear, depending on the amount of ligament involved may heal on its own, and patient may recover by use of physical therapy. If the patient has high grade partial ACL tear, then these patients may not recover completely, and depending on the requirement of the patient, may need to undergo surgical reconstruction of the ACL.
Can ACL be repaired?
ACL tears if present early after injury and if MRI show that they are reparable, then a trial for repair can be given to the ACL. The ligament is fixed back to the bone using some sutures and buttons to allow a natural healing process and keep the native ligament in its place. Repair leads to early recovery and owing to the retention of native ACL, gives better proprioception and hence early rehabilitation and recovery.
Is ACL repair better than reconstruction?
ACL repair, if possible, give better result than reconstruction because in ACL repair, the native ligament is kept as such and is fixed back to the bone to allow healing. In case of reconstruction, a ligament substitute is put in place, which not only takes a longer time to heal, but also takes time for ingrowth of nerves and vessels, which may also still be incomplete to give a result similar to an ACL repair.
How long before I can return to sporting activity after an ACL reconstruction?
After an ACL reconstruction, patients must be involved in a rehabilitation program with the physical therapy under direct supervision of the therapist and the treating physician. Patients must be in brace initially, which is gradually weaned off in four to eight weeks. Patient is put in rigorous physical therapy program and is also allowed to strengthen his muscles in the gym after about three months from surgery. Patients must strengthen their quadriceps as well as the hamstrings and must regain full range of motion and power before they can indulge in a sporting event. They are puts into sports rehab program. It could take six to twelve months before a professional sportsman can return to play.
How long does it take to recover from a torn ACL?
A torn ACL, when treated surgically, may take up to 6 to 12 months to recover completely and allow the patient to do unrestricted activities as before the injury. In patients who do not opt to operate may have a long rehabilitation process with suboptimal results, but if the results allow the patient to live a satisfactory life in their activities of daily living as well as work and recreation, then the result is found to be okay.
What are the risks of ACL surgery?
The risks of ACL reconstruction arthroscopically include Medical (Anesthetic) complications like but not limited to: Allergic reactions, excessive blood loss, heart attack, stroke, kidney failure, pneumonia, bladder infections. Complications from nerve blocks such as infection or nerve damage. Complications due to surgery itself include infection, DVT, excessive swelling & bruising, joint stiffness, tingling and numbness, graft failure, damage to nerves or vessels, hardware problems, donor site problems, residual pain, reflex sympathetic dystrophy etc. Some of these conditions may require hospitalization, aspiration, injections or even surgery.
How long do you have to keep your leg elevated after ACL surgery?
Patients are encouraged to keep their knee elevated most times for a few weeks after ACL surgery. This is to decrease the swelling as well as the pain in the knee. Once the patient’s pain has decreased and the swelling is no longer there, the patient can decrease the time of leg elevation. If the pain and swelling recur, then the patients are instructed to use ice as well as elevation and compression to decease the pain and swelling.
How long does it take to be able to walk again after ACL surgery?
Patients can walk within a day after the ACL surgery with a brace. They are also asked to use crutches for support. Patient will be using a brace for four to six weeks. They may use auxiliary crutches for support, if needed.
How long do you have to be on crutches after ACL surgery?
Patients, after ACL surgery, have a brace on the knee, and may use auxiliary crutches for comfort. They may discard the crutches once they are able to ambulate without discomfort.
Is ACL surgery serious?
ACL reconstruction, or repair surgery of the knee, is one of the major arthroscopic surgeries of the knee. It involves inspection of the joint, with repair, or reconstruction of the ACL along with treatment of any associated injury like meniscal tear. The surgery itself may take one and a half to two hours to complete. The rehabilitation process after the surgery is tedious, and involves constant supervision with a physical therapist, and a physician.
How long do you go to physical therapy after ACL surgery?
Patients usually must go for six to nine months of physical therapy after an ACL reconstruction, for it to recover completely, from ACL surgery, depending on the patient’s requirement. If the patient is a sportsman, they may have to go to a sports rehabilitation program so as to recover completely, to a pre injury status.
Can a stretched ACL heal?
A stretched ACL can be treated with a brace and physical therapy and may heal over time enough to provide a patient with a stable knee. If the patient does not heal completely with the brace, and physical therapy, and is still unstable enough to handle activities of daily living, or work, without limitation, then he may need to undergo ACL reconstruction surgery.
When can I take a shower after ACL surgery?
Patients are usually asked to remove their dressing after 72 hours of surgery, and can take a shower after that. Patient can dab the surgical area dry and put band aids over it.
Can an ACL reconstruction/repair fail?
An ACL reconstruction/repair can fail, due to multiple reasons, including wrong surgical technique, injury, fall, or twisting of the knee. ACL surgery may also fail in the presence of infection. In case of ACL repair, surgery may fail to heal the native ligament and a reconstruction may have to be done. These patients may need to undergo a revision of the ACL reconstruction, to get a stable knee.
Do torn ligaments heal themselves?
Torn ligaments of the knee, if in place, and of low grade (partial), can heal by themselves. The lateral collateral, as the medial collateral ligaments are essentially treated conservatively with brace and physical therapy. In case of high grade ligament tear, and if the patient is not getting better with physical therapy and brace, the patient may need a surgical repair, or reconstruction of the ligament, to obtain stability.
How ACL surgery is done?
ACL surgery is most commonly done arthroscopically, in which a camera and a light source are introduced to the knee joint through small incisions. Surgical instruments are inserted through different incision, and the ACL is examined. If the ACL is completely torn, and not repairable, then it is debrided, and cleaned.
The replacement substitute for the ACL is then harvested, either from the hamstring muscles, patellar tendon, or the quadriceps tendon, to replace the ACL. Bone tunnels are then made into lower end of femur, and upper end of tibia to pass the graft, and the graft is fixed using sutures, and either screws or buttons. Any concomitant pathology if found inside the knee is also taken care of.
How long are you out for the torn ACL?
The torn ACL is usually treated non-surgically and may take up to eight to twelve weeks to heal. A patient is usually treated with a brace, and physical therapy. Patient may be out of work, depending on the type of work, from two weeks to eight weeks. If the patient is in high demand job with a lot of manual work, then they may be out for a longer period.
How long does it take to recover from an ACL and meniscus surgery?
The recovery of a combined surgery is a little longer than that of an ACL surgery. There are s slightly higher chances of complications and stiffness owing to increased surgical time and work done inside the knee. The loss of partial meniscus in cases of partial meniscectomy also plays a role in long term recovery of the knee. In cases of meniscus repair, the rehabilitation is slowed due the time needed for the healing of the meniscus.
Can ligaments grow back together?
If the ligament is in it’s place, especially near the, it’s, bony end, then they may heal with the help of bracing and physical therapy. If the ligaments are torn in mid substance then it is difficult for them to heal, because the healing between the two ends of ligaments is not optimal. The ligaments usually do not grow back, but they heal with a fibrous tissue between them.
How do you prevent an ACL tear?
The ACL tear is essentially caused due to injury or fall or contact sports. If a person is involved in high risk activities like contact sports, then they are advised to have strong musculature, especially in the quadriceps and the hamstrings, as this support the knee, hence preventing an ACL tear. If the patient has undergone an ACL reconstruction, or repair, surgery then they are instructed to strengthen their quadriceps as well as hamstrings before they go back into field, to prevent repeat tear of the ACL.
What are the causes of a torn ACL?
An ACL is usually torn due to fall, or injury, especially involving twisting of the knee, or with an indirect force; someone hitting the knee. This usually happens in a contact sport accident, but this may also happen in injuries, like automobile accidents.
Can I do without my hamstrings?
Patients who undergo ACL reconstruction using their hamstring muscles can still walk and function well with their knee with rehabilitation because of other muscles substituting for those hamstring tendons as well as partial or complete regeneration of the tendons.
Should I wear a knee brace to support my knee rather than undergo major surgery for ACL reconstruction?
Surgery for ACL reconstruction is essentially an elective surgery in which the patient must discuss and understand the need for the surgery. If the patient is symptomatic enough to have inability of daily living, work and/or recreation, then it is advisable to undergo ACL reconstruction. Wearing a knee brace cannot substitute for a deficient ACL and patient will still will have restriction with regards to his activity. The knee brace may help in stabilizing the knee for certain movements, but the patients will still not be able to perform a higher level of function with that knee.
How can I tell if I have got a serious ACL injury?
Patients with ACL injury do remember incident in which they may have injured their knee. This is usually associated with, swelling of the knee, pain along with limping. If the patient presents late, they may have symptoms of instability in which they would have knee buckling or weakness because of deficiency of the ACL. A diagnosis of ACL injury is usually made by examination followed by an MRI of the knee.
Dr. Vedant Vaksha
I am Vedant Vaksha, Fellowship trained Spine, Sports and Arthroscopic Surgeon at Complete Orthopedics. I take care of patients with ailments of the neck, back, shoulder, knee, elbow and ankle. I personally approve this content and have written most of it myself.
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