Anterior Cruciate Ligament (ACL) Injuries

One of the more serious knee injuries an athlete can sustain is a tear of the anterior cruciate ligament, more commonly known as the Anterior Cruciate Ligament (ACL). ACL tears are usually seen in high contact or collision sport athletes. Although more common in higher-impact sports, an ACL injury is usually sustained when there is no contact made. When an athlete tears their ACL, it is more than likely that the athlete planted their foot, twisted, and felt a pop in their knee. The phrase used to describe an ACL tear is “deceleration with internal rotation”. When the ACL is torn, another injury may be present as well. Common associated injuries are a torn meniscus and/or medical collateral ligament (MCL). Less commonly involved are the lateral collateral ligament (LCL) or posterior cruciate ligament (PCL).

ACL tears can occur in both males and females. However, research by Dr. Ahmad and other leaders in Sports Medicine have determined that ACL tears are more likely in females. The reason ACL injuries are more common in females is due to a larger Q-angle. The Q-angle is the relationship of the hips to the knee. The larger someone’s Q-angle, the wider the hips. Additionally, experts have proposed other theories as to why females are more likely to tear their ACL including: differences in physical conditioning, muscular strength, neuromuscular control, increased looseness in ligaments, and the effects of estrogen on ligament properties.

Once an ACL injury has occurred, it is necessary to assess the extent of the injury. The first step is to have your knee evaluated by Dr. Ahmad and his team. Once evaluated, an MRI is typically necessary to determine the status of the ligament. Unfortunately, ACL tears do not heal on their own and surgery is the general course of treatment. Depending on the type of tear, you may have two surgical options: an ACL Reconstruction or an ACL Repair. The type of surgery depends on how Dr. Ahmad interprets your MRI scan.

ACL injuries can occur in all sports but are most common in: soccer, basketball, football, lacrosse, and skiing.

Anatomy of the Knee

Anatomy Of The KneeThere are three bones that make up your knee: the femur (thigh bone), tibia (shin), and patella (knee cap). Sitting on top of the tibia, are two ‘C’ shaped pieces of cartilage called the meniscus. The menisci are the shock absorbers of the knee. Ligaments connect bone to bone, and there are four major ligaments in the knee: the ACL, PCL, MCL, and LCL. One way to think of the ligaments is as ropes that connect the two bones and limit certain movements between the bones it connects. The ACL is the main stabilizer of the knee and connects the femur and tibia. It limits forward translation of the femur on the tibia. When a ligament tears, imagine that the rope has frayed completely through.


The anterior cruciate ligament can be injured in several ways:

  • Quickly pivoting
  • Suddenly stopping or slowing down while running
  • Landing from a jump incorrectly
  • Direct contact or collision, such as a football tackle or being slide tackled in soccer.


When the ACL is injured, an audible “pop” may be heard and the knee may give out. Other symptoms may include:

  • Pain
  • Swelling
  • Loss of full range of motion
  • Tenderness along the joint line
  • Discomfort or pain while walking
  • Feeling of instability

In some cases swelling and pain could resolve on its own within 24 hours. However, if an attempt to return to sports is made, the knee could be unstable and there is an increased risk of injuring other structures in the knee.

Dr. Ahmad’s Knee Examination

Physical Examination and Patient History

Dr. Ahmad’s knee examination is comprised of a few different components: a history, observation, palpation, special tests, imaging and assessment. At your initial visit, Dr. Ahmad and his team will ask you pertinent questions about your injury. Once a thorough history is obtained, Dr. Ahmad performs a physical examination that is a combination of observation, palpation, and special testing. During this part of your exam, Dr. Ahmad compares the injured knee to the healthy side and will check all the structures of your injured knee while locating important landmarks and checking range of motion. Special testing is a key part of the diagnosis process. The tests Dr. Ahmad performs help our team establish a diagnosis and determine which treatment route will give our patient a most favorable outcome. In addition to a clinical work-up, imaging may be necessary to determine the extent of the injury. Imaging almost always includes an MRI.

Imaging Tests

Knee Imaging TestsMagnetic resonance imaging (MRI) scan: An MRI is used to determine soft-tissue damage. Compared to an X-ray, an MRI consists of images better suited to evaluate the status of the ACL. Additionally the MRI can confirm if other structures are injured.

Surgical Treatment

Using our analogy where the ligament is thought of as a rope, the damage done to the rope will help Dr. Ahmad determine which option is best for you. If the ligament is torn through the middle where it appears like two ends of a mop, a reconstruction is generally your option. Conversely, if the ligament, or rope, is still intact but torn or peeled away from an attachment site on the bone (either femur or tibia) a repair may be your surgical option. Dr. Ahmad will review your MRI, discuss your options, and recommend what may be your best surgical option.

ACL Tear (Left) and ACL Construction (Right)

ACL Tear (Left) and ACL Construction (Right)

ACL Reconstruction
An ACL reconstruction is performed when the ligament is torn and resembles two mop ends. Dr. Ahmad performs an ACL reconstruction arthroscopically, where two small incisions are made on both sides of the patella for Dr. Ahmad to pass the camera (arthroscope) and other instruments into the joint. After tunnels are drilled into both the femur and tibia, the graft is passed through both tunnels and fixated by screws. There is typically another incision where the graft is taken from. Patients usually have three types of graft choices to reconstruct the ACL. Two are called autograft and the third is called an allograft.  An autograft is where the tissue is taken from the patient’s own body. These two options are a hamstring autograft or a bone-patella tendon-bone autograft. The third option is allograft tissue. Allograft tissue comes from a donor and is treated so it is safe for a recipient to use. There are a number of different factors which play a role in graft choice for each individual patient and Dr. Ahmad will guide you to which graft is your best option.

Knee Post Op Xrays

Post-operative X-rays of the tunnels in a patient with bilateral ACL reconstructions done by Dr. Ahmad.

ACL Repair
When the ACL does not tear in two, a repair may be possible for Dr. Ahmad to perform which salvages the native ligament. ACL repairs are also performed arthroscopically, where two small incisions are made on both sides of the patella for Dr. Ahmad to pass the camera (arthroscope) and other instruments into the joint. To repair the ACL, Dr. Ahmad sutures the ligament to the attachment site. This procedure is innovative and patients with a repair do just as well as a reconstruction post-operatively.

Surgery Details and Post-Op Care
Both surgical options are performed in an out-patient setting where the patient comes in, has surgery, and goes home in the same day. The time of your procedure will dictate what time you have to arrive at the facility. Surgery itself takes roughly an hour and post-operatively the patient will be in the post-anesthesia care unit (PACU) for 2 to 3 hours depending on how they react to the anesthesia. Anesthesia used is in the form of a nerve block and light sedation, not general anesthesia. The nerve block can last between 8 and 24 hours. Crutches are used post-operatively and, in most cases, patients will be allowed to weight-bear as tolerated; meaning that patients can put as much or as little weight on the knee as they can tolerate. Dr. Ahmad and his team will explain weight-bearing status in the PACU. In addition to crutches, a large ace wrap and range-of-motion brace are also applied to the knee post-operatively. The brace is typically worn throughout the day and night for 4 to 6 weeks after surgery.

After 24 hours, patients are able to remove the dressing and brace and shower. The brace must be reapplied after showering. Patients are allowed to perform straight leg raises, quad sets, and other exercises to help get the quadriceps muscles firing and prevent muscle atrophy. Physical therapy starts within days of having surgery. There are a few medications that are prescribed for any post-operative discomfort and our team will go into details in the office should you be a candidate for surgery. Our team will explain all details of surgery in the office as well as post-operative care at length and answer all questions that may come up!

Rehabilitation and Return to Sports

Physical Therapy plays an important role in getting you back to your daily activities and sports. In some cases prehab will be necessary to decrease swelling and increase range of motion prior to surgery. Not everyone needing surgery will need to do prehab although performing exercises like straight leg raises, quad sets, and flexion exercises prior to surgery will play a large role in post-operative recovery.

Post-operatively, physical therapy primarily focuses on regaining quad control, restoring range of motion, and decreasing swelling. Low level strengthening is also important through exercises such as quad sets, straight leg raises, and flexion exercises. As range of motion is improving, strengthening the muscles is incorporated and is designed to protect the new ligament. As strengthening progresses, more stress is applied to the ligaments and muscles of the knee preparing it for the final phase of rehab. The final phase of rehab is aimed at a functional return to play tailored to the athlete’s sport.

Return to Sports
The rehab process is a gradual progression leading up to a return to play. There are a few milestones along the rehab course that each athlete will reach prior to return to sport. At the 3 month mark, athletes are allowed to begin running straight ahead. Around post-op month 4, more sport specific drills come into play but it is not until at least the 6 month period that athletes are allowed to perform sport-specific tasks with an opponent on them (such as dribbling a soccer ball past an opponent or taking a basketball shot with a defender contesting it). Generally when the athlete is getting ready for a return to sport, Dr. Ahmad recommends a customized brace that is used until the 1-year anniversary from surgery.

*Note: All timelines are meant as a guide and each player’s actual timeline may vary.*

ACL Videos

ACL Reconstruction

Patient Story

Mackenzie had ACL reconstruction surgery in February 2015, at age 13. She plays competitive lacrosse and ice hockey.

“When I tore my ACL I wasn’t sure if I could return to playing my favorite sports at the same level as before. I went to see Dr. Ahmad at Columbia Orthopedics and he reassured me that after surgery and some hard work I would be able to return to playing at the same level or even better. 6 months later I was finally able to return to sports. Tearing my ACL was a horrible thing but it also made we work harder to get back into shape. With the support of Dr. Ahmad and his team I was able to make the JV Lacrosse Team where I was later named Captain. That season I scored 50 goals in 15 games and was named the MVP. I am also the only girl on a boy’s ice hockey team. I want to thank Dr. Ahmad and his entire team for all they did to make me a better athlete.”

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