ACL Tear & Reconstruction – Knee Ligament Injury

ACL Physician in Dallas, Texas


The anterior cruciate ligament, commonly known as the ACL, is one of the most injured ligaments in the knee. Ligaments are thick fibers that connect our bones together. The ACL connects the thigh-bone to the leg. It is responsible for providing stability to the knee joint.

Torn ACLs are more common among athletes. The ACL is more likely to tear with abrupt movements or abrupt halts, similar to the actions frequently performed during sports, such as football, basketball, skiing, and soccer.

The ACL can be torn completely or partially. Unlike most of the body parts, the ACL is unable to repair itself. This means that when the ACL is injured, it is commonplace to see other knee structures damaged, as well. A torn ACL can be treated either nonsurgically or surgically.

Knee Anatomy

Bones in the Knee

The knee is one of the more structurally complex areas of the body. The knee is composed of three bones:

  • The Tibia, or shinbone
  • The Femur, or thighbone, sits on top of the tibia, the larger leg bone.
  • The Patella, or kneecap, glides in a groove on the end of the femur.

Muscles in the Thigh

Large muscle groupings in the thigh give the knee its strength and stability:

  • The quadriceps muscles-group of muscles on the front of the thigh that straighten and rotate the leg.
  • The hamstring muscles- located on the back of the thigh and bend or flex the knee.

Ligaments Surrounding the Knee

Ligaments are strong tissues that provide stability and allow the leg to move. They also enable flexibility while maintaining balance. Four ligaments connect our knee bones together:

  • The medial collateral is located on the inside of the knee, and the lateral collateral is at the outer side of the knee. These two ligaments help the joint to resist side to side stress.
  • The anterior cruciate ligament and the posterior cruciate ligament cross each other inside of the knee joint. These ligaments help to keep the joint aligned. They also counteract forward and backward forces and keep the bones in place. They also control rotation of the tibia.

Cartilage, Synovium, and Nerve Fibers

Two cartilage disks, Menisci, are located on the end of the tibia. This cartilage forms a smooth surface, allowing the bones to glide easily during motion. The menisci act as shock absorbers when we walk or run.

A smooth tissue capsule covers the bones in our knee, and a thin synovial membrane lines this capsule. The synovium secretes a liquid known as synovial fluid. The synovial fluid acts as a cushion and lubricant between the joints, which allows the knee to move painlessly. Proprioceptive nerve fibers are inside in the ligaments and joint capsules, sending signals throughout the body.

ACL Tear Causes

The ACL can tear during harsh twisting motions and can also tear if the knee is hyperextended or bent backwards. ACL tears occur most frequently in younger athletes.Female athletes have a higher rate of ACL tears than males.

ACL tears don’t usually come by themselves. Surrounding structures in the knee, such as the meniscus, cartilage, and ligaments can be injured as well as bruised or broken bones.

ACL Tear Symptoms

Individuals usually experience pain, swelling, and knee instability immediately after the ACL tears. It is common to hear of the knee “buckling”, or “giving out”. The knee may be unable to fully extend and have difficulty moving.

ACL Tear Diagnosis

If you suspect you have torn your ACL, you should seek immediate medical attention. A doctor can evaluate your knee and will examine your knee and your leg alignment. You may be asked to perform simple movements to help the doctor determine muscle strength, joint motion, and stability.

Lachman Test

Most doctors perform the Lachman Test to determine if the ACL is intact. For this, the patient lies on his or her back and slightly bends the knees. The doctor then places one hand on the thigh and attempts to pull the leg forward with the other hand, comparing one leg to the other. If the leg can move three to five millimeters, the test is positive for an ACL tear.

Pivot Shift Test

The Pivot Shift Test is another popular test used by doctors to determine if the ACL is functioning. For this test, the patient straightens the leg. The doctor then holds the leg while turning it and moving it toward the body. If the leg moves in and out of position, the test is ACL tear positive.

ACL Tear Treatment

Immediately after an injury, your knee will need to be treated with RICE: rest, ice, compression, and elevation. Resting the knee means staying off of it. If you must walk, use crutches. Applying ice packs to your knee can help reduce pain and swelling. Elevating and icing the knee will help to reduce swelling. A doctor may recommend an icing schedule as well as a knee brace.  

Treatment for ACL tears varies around several factors, such as your activity level, severity of injury, and degree of knee instability.

The treatments may include physical therapy, surgery, or both. In order to be a candidate for a non-surgical treatment, the patient must have partial ACL tears without knee instability, complete tears without knee instability, live a sedentary lifestyle, or are children whose knees are still developing.

Physical therapy and rehabilitation can help restore knee’s function. The physical therapist will help strengthen the knee, with a special emphasis placed on exercising the quadriceps.

ACL Tear Surgery

Surgical treatment is recommended for those with ACL tears along with other injuries. Patients who are active individuals, whether it be sports, job, or lifestyle, in general. It is also recommended for those with unstable knees and have multiple injuries, such as damage to the meniscus, articular cartilage, joint capsule, or ligaments.

In most cases, patients are advised to participate in physical therapy. Swelling can make the knee stiff, and immobility can cause the muscles and ligaments to actually shorten. A physical therapist will help to stretch the knee to regain full movement. However, if the collateral ligaments are involved, a brace may be needed prior to your surgery.

During surgery, the surgeon will replace your damaged ACL with a graft.

Patellar Tendon Autograft

A patellar tendon autograft will use the middle section of the patellar tendon and bone plugs from the shin and kneecap. This type of surgery is often recommended for high-demand athletes and individuals that do not have to perform a lot of kneeling activities.

Hamstring Tendon Autograft

A hamstring tendon autograft uses either one or two tendons from the hamstring muscles. The hamstring tendon autograft is suitable for smaller or fit individuals with a small patella bone and a history of pain. This method is known to have a faster recovery time

Quadriceps Tendon Autograft

A quadriceps tendon autograft uses the center of the quadricep tendon and a bone plug from the upper end of the kneecap. This type of graft is large and is most appropriate for taller and heavier individuals or for individuals for whom an ACL surgery has failed in the past.


Allografts are taken from cadavers and are most suitable for:

  • Patients who have a history of pain
  • Older patients that are moderately active
  • Patients with prior failed ACL reconstructions
  • Patients wanting to return to sports quickly
  • Patients that need more than one ligament reconstructed

ACL Reconstruction

Many ACL reconstruction surgeries are outpatient procedures. The patient may either be anesthetized for surgery or receive a nerve block. The surgeon will make one or more small incisions, about a quarter to half inch in length, near the joint. The surgeon will fill the joint space with a sterile saline solution, to expand the area. The surgeon will then insert an arthroscope and will reposition it to see the joint from multiple angles.

After this, the surgeon may make more small incisions. The new graft is attached using surgical hardware. The surgeon will then test the new graft and the knee’s function. Again, the surgeon will examine the knee by performing similar muscle tests conducted during the clinical examination to ensure that the knee is stable and has a full range of motion.


Most patients may go home the same day after surgery and are sent home with pain medication to help the post-surgery pain.The doctor may advise ice or to keep the leg elevated and may also prescribe blood thinning medication and special support stockings.  

In some cases, the doctor may prescribe compression boots and a continuous passive motion, or CPM, machine. These are inflatable leg coverings that attach to the CPM machine. This works by gently squeezing the legs to aid blood circulation, decrease swelling, and restores movement back to the knee.

Walking and movementing are a critical component of your recovery. Exercising, or physical therapy, usually begins right after the surgery. At first, the patient will need to use a walker or crutches while moving. Later, the doctor may prescribe a knee brace. It can take four to six months to restore the coordinated leg movements.

An occupational therapist can show you how to complete everyday tasks with your movement restrictions, such as getting dressed, bathing, etc.

Following the come care instructions is crucial to your success. In fact, it’s dependant on it. As with most surgeries, the recovery times will differ depending on the severity of the injury, the type of procedure, and the patient’s overall health. Generally, most patients should be able to resume some of their regular activities in as little as one to three weeks after his or her procedure. The majority of patients can resume functional activities after ACL reconstruction.


It is crucial and critical that the patient adheres to the exercise program and safety precautions given by the doctor, while staying as active as possible.


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