Torn ACL In Knee

By Christopher C. Dodson

Last Updated on January 1, 2024 by The SportsMD Editors


torn acl

Most clinicians describe a torn ACL in the knee as either partial or complete and symptoms include hearing a loud pop as the ligament tears, pain, knee swelling, and difficulty walking.  The anterior cruciate ligament (ACL) is one of the four major ligaments that connect the bones of the knee joint. The ACL ligament helps to hold the

bones in proper alignment and helps control the way your knee moves. The ACL provides stability to the knee and prevents excessive forward movement of the lower leg bone (tibia) in relation to the thigh bone (femur) as well as provides rotational stability to the knee,” according to the American Academy of Orthopaedic Surgeons.


What causes a torn ACL in Knee?

A torn ACL can be grouped into two categories: contact and non-contact.

Non-contact injuries would be when an athlete rapidly decelerates, followed by a sharp or sudden change in direction (cutting). Noncontact torn ACL injuries have also been linked to heavy or stiff-legged landing as well as twisting or turning the knee while landing, especially when the knee is in the valgus (knock-knee) position.

Contact injuries most commonly occur after a blow to the outside of the leg causing the knee to “buckle” and assume a valgus position.


How is a torn ACL classified?

Most clinicians describe a torn ACL as either partial or complete. This is based on physical examination and imaging findings (discussed later).


Do women really tear their ACLs more than men?

Women in sports such as soccer, basketball, tennis, and volleyball are significantly more prone to a torn ACL than men. The discrepancy has been attributed to differences between the sexes in anatomy, general muscular strength, reaction time of muscle contraction and coordination, and training techniques. Hormonal causes have also been investigated although it is still unclear what role they may play in an ACL tear if any. Lastly, women have a relatively wider pelvis, requiring the femur to angle toward the knees (knock knee) which may also be a predisposing factor towards a torn ACL.  Please visit ACL Injury in the Female Athlete to learn more.


Torn ACL Symptoms

Patients who suffer an ACL injury often report symptoms of hearing an audible pop followed by significant swelling. Afterwards, patients may complain of instability of the knee (i.e., a “wobbly” feeling) especially when trying to change directions during sporting activity. Continued athletic activity on a knee with a torn ACL can have devastating consequences, resulting in massive cartilage damage, leading to an increased risk of developing osteoarthritis later in life.


Diagnosis of torn ACL

torn aclSeveral diagnostic maneuvers help clinicians diagnose a torn ACL.

  • The anterior drawer test, the examiner applies an anterior force on the proximal tibia with the knee in 90 degrees of flexion (picture).
  • The Lachman test is similar, but performed with the knee in only about twenty degrees of flexion, while the pivot-shift test adds a valgus (outside-in) force to the knee while it is moved from flexion to extension. The Lachman and anterior drawer assess purely for translation, whereas the pivot shift test assesses for rotational instability. Any abnormal motion in these maneuvers suggests a tear.
    The diagnosis is confirmed of a Torn ACL on an MRI (magnetic resonance imaging) which also is used to assess for other ligament, meniscus, and cartilage pathology.



What happens if you don’t repair a torn ACL in Knee?

Nonsurgical options may be used if the knee cartilage is undamaged, the knee proves to be stable during typical daily activities, and if the patient has no desire to ever again participate in high-risk activities (sports involving cutting, pivoting, or jumping). Nonsurgical treatment is typically only considered in cases of low grade partial injuries. If the nonsurgical option is recommended, the physician will recommend physical therapy, wearing a Torn ACL Brace, and avoiding any provocative maneuvers. The goal of physical therapy is to strengthen the muscles around the knee to compensate for the absence of an ACL. Initially the goal of physical therapy is to restore range of motion; after a period of time, the physician will prescribe a strengthening program that focuses on the hamstrings first and later the quadriceps, hip, and core musculature. Most ACL-deficient athletes conclude that their knee continues to feel unstable, again confirming the important role of the ACL in normal knee stability.

Therefore, most orthopaedic surgeons recommend ACL surgery treatment in the athletic population because repetitive insults to the knee as a result of ACL deficiency often results in meniscal and cartilage injury.

Such injuries can ultimately lead to persistent pain, disability, and premature osteoarthritis. However, initially, sports injury treatment using the P.R.I.C.E. principle – Protection, Rest, Icing, Compression, Elevation can all be applied to a torn ACL.


Torn ACL Surgery

There are two main acl surgery options for Torn ACL graft selection: autograft and allograft.

  • Autografts are the patients’ own tissues, and the most common options include the middle third of the patella tendon and the hamstring tendons.
  • Allografts are cadaveric tissue sourced from a tissue bank; the most common allograft tissue used for ACL reconstruction is Achilles tendon.

Each method has its own advantages and disadvantages; patellar tendon autografts are the most common and often considered the gold standard for young highly competitive athletes. However, the site of the harvest is often painful for weeks after surgery and some patients can develop tendinitis or generalized knee pain that can be difficult to recover from. Such complications are generally avoided when using hamstring autografts, although some clinicians feel hamstring reconstructions become loose over time. It should be noted that many clinicians used both with an extremely high success rate and their use is often surgeon preference or bias. ACL surgery reconstruction using allograft tissue does carry a slightly higher infection risk but patients often recover the fastest of all the graft choices.

Although not recommended for young, extremely active athletes, allograft reconstruction is often a popular choice for the older more sedentary athlete.

Many patients worry about the transmission of disease from the allograft itself; although this has been reported in the literature, most clinicians feel such risk is extremely low and feel very comfortable using allograft tissue.

The ACL surgery is performed arthroscopically, with tunnels drilled into the femur and tibia at the original of the ACL footprints. The graft is then placed into position and held in place. There are a variety of fixation devices available, particularly for hamstring tendon fixation. These include screws, buttons and post fixation devices. The graft typically attaches to the bone within six to eight weeks. The original collagen tissue in the graft acts as a scaffold and new collagen tissue is laid down in the graft with time.

What is the recovery time for ACL Surgery

Recovery time for ACL  surgery can range from 4 to 8 months (or longer), depending on the surgical technique and severity of the injury. Learn what you can do in the meantime to speed up recovery.


What is double bundle ACL reconstruction and do I need it?

Since the native ACL consists of two bundles, some clinicians have advocated a double bundle reconstruction which places two separate grafts during surgery instead of just one. Although biomechanical studies have shown an advantage in this technique, no clinical studies have demonstrated it to be superior to standard single graft techniques. Furthermore, it is unclear what the potential disadvantages of a double bundle technique are. Most clinicians still use a single graft approach with very high success. It is important to consult your surgeon to discuss what his/her preference is and why.


Physical therapy after ACL surgery?

After ACL surgery, the knee joint loses flexibility, and the muscles around the knee and in the thigh tend to atrophy. All treatment options require extensive physical therapy to regain muscle strength around the knee and restore range of motion (ROM). For some patients, the lengthy rehabilitation period may be more difficult to deal with than the actual ACL surgery.


Torn ACL Brace

A torn ACL brace is recommended for athletes in contact and collision sports for a period of time after reconstruction. It is important however to realize that many of the specific rehabilitation protocols are physician dependent. Generally speaking, most surgeons will prescribe a brace and crutches for post ACL surgery recovery for approximately one month. After that, a rehabilitation period of six months to a year is required to regain pre-surgery strength and use.

Rehab after ACL surgery can vary widely, but there are some general principles that are true for most patients having surgery for treatment of an ACL. Start strengthening exercises only after you have your health professional’s approval. The list below provides links to specific rehab ACL video exercises:


Torn ACL recovery time

Most clinicians allow for a competitive return to sport at six to seven months and most people are able to return to their sport within six to nine months, according to

There should be a balance between trying to do too much work in physical therapy and doing too little. Being too aggressive with strength and range of motion exercises can damage the surgical repair and cause the ligament to fail again.

Too little work lengthens the time to return to normal activities.

  • In the first two to four weeks, the goal for physical therapy is to increase range of motion of the knee. The ligament graft needs time to heal in so too much bending is discouraged so that the graft doesn’t rip. The goal in the first four weeks is full straightening of the knee and 90 degrees bending.
  • In the next four to six weeks, the goal is to return the knee to full range of motion.   Your physical therapist may also add strengthening exercises and bicycles or stair-climbers are often used.
  • For the next five to six months, the goal is to increase strength and agility while maintaining range of motion. The progress should be closely monitored by the surgeon and physical therapist.

It is often recommended to protect the knee with an ACL Knee Brace through the rehabilitation process. It’s also recommended to continue wearing a brace after the ACL has healed, especially during sporting activities to decrease the risk of re-injury.


ACL injury prevention

Athletes can lower their risk of torn ACL by participating in performance drills that focus on improving lower extremity strength, agility, flexibility, and power. The Santa Monica ACL Prevention Project developed an ACL Injury Prevention Program specifically designed for female soccer players that can be applicable for all athletes both male and female.

USC spent over 10 years researching movement patterns related to lower extremity injury and the factors that contribute to their development. Through their research and years of experience training athletes they have developed an ACL Project Prevent program directed at coaches and athletes of local soccer teams and clubs.

The ACL prevention program includes:

  • Education for players and coaches about injury prevention
  • Individual movement assessment
  • On-field training of exercises and drills aimed at improving skills and decreasing risk for injury
  • Structured injury prevention warm-up program
  • Written exercise descriptions

Download this pdf outline from The Santa Monica Sports Medicine Research Foundation. The PEP Program:  Prevent
injury and Enhance Performance.

Professional athletes with Torn ACL

torn aclPayton said of the third-year pro, who is coming back from a torn ACL that sidelined him for the entire 2016 season. Kikaha also tore his ACL in his left knee twice in college, but he returned from those injuries to finish with 32 sacks over his final … Saints’ Hau’oli Kikaha a comeback expert after three ACL tears – ESPN (blog)

torn aclTAMPA — Bucs rookie LB Kendell Beckwith is eight months and a week removed from November surgery to repair a torn ACL, so he had a proud sense of accomplishment in being healthy enough to be on the field for the opening practice of training camp …FanRag Sports (blog) Bucs journal: Rookie LB Kendell Beckwith healthy after torn ACL –

torn aclThis is Bernard’s second torn ACL. He tore his right ACL as a freshman at North Carolina before the 2010 season but recovered for spring practice. “When people say ‘Oh, you came back so quick,’ I just always tell them I’m Haitian and we’re just born …Bengals.comFantasyProsIdaho Statesman Giovani Bernard ready for season after 8-month ACL rehab process – ESPN

Find a Doctor who specializes in Torn ACL:

You can contact SportsMD at and we’ll help you find a top sports specialized orthopedic doctor in your area.

Other options include:

American Orthopedic Society for Sports Medicine
6300 North River Rd.
Suite 200
Rosemont, IL 60018
Toll-Free: (877) 321-3500

American Academy of Orthopaedic Surgeons (AAOS)
6300 North River Rd.
Rosemont, IL 60018-4262
Toll-Free: (800) 346-2267

Can Telemedicine Help?

Telemedicine is gaining popularity because it can help bring you and the doctor together quicker and more efficiently. It is particularly well suited for sports injuries such as sprained wrist and facilitating the diagnoses and severity of the injury and treatment plan.  Learn more via SportsMD’s 24/7 Telemedicine Service.