What is Anterior Cruciate Ligament injury?

ACL Injury

In the body, a special cellular material that functions much like an elastic band to connect tissues to bones and form the basis of joints is known as a ligament. For example, the area of the body known as the knee “joint” has no fewer than four different elastic bands or ligaments for proper function and stability. Two of these elastic bands intertwine as they link the front lower bone of the lower extremity to the larger upper bone of the lower extremity, referred to by doctors as the anterior (front) and posterior (rear) cruciate ligaments. These elastic bands are essential for a number of different flexions that keep the knee joint stable while allowing for lateral and forward motion.

An ACL affliction is when some form of trauma or damage has resulted in a tear or rupture of the critical front (anterior) cruciate elastic band. An ACL wound can also refer to additional damage that has occurred inside the knee itself such as to the special shock-absorbing tissue cups known as menisci. Although injuries can occur to other ligaments in the lower extremity, sports medicine experts have noted that the ligament in the front or forward-facing portion of the leg is especially vulnerable to damage by individuals engaged in vigorous sporting activities that are most commonplace today. Often referred to simply as “ACL” for short, damage to the anterior cruciate ligament is by far the most common type of ligament injury sustained by professional athletes today.

ACL injury symptoms and causes

While it is rare for inactive people to be afflicted with damage to the ACL, it is certainly possible. The vast majority of individuals who sustain an ACL affliction are athletes who are engaged in playing vigorous sporting activities like basketball, soccer or American football. Sports medicine experts know that the majority of ACL wounds occur when a twisting torque is applied to the front elastic band followed by a rapid deceleration in the opposite direction, effectively twisting the ligament beyond its breaking point and resulting in either a complete separation or a ripping of the front lower extremity elastic band.

Although it is only poorly understand as to cause, sports medicine experts have documented that ALC afflictions strike women more predominantly than men even in cohorts participating in the same sporting activity. Another strongly-correlated etiology for developing an ALC affliction is having an irregularly formed knee joint.

Types of ACL injuries

Sports medicine experts now use established criteria for categorizing the depth and severity of an ACL affliction using a numerical grading system.

Level 1 – The least severe category of an anterior cruciate ligament affliction, presented with a moderate to minimal amount of tissue damage and characterized by a strain placed on the elastic band.

Level 2 – A more significant level of damage, presented with a noticeable increased in inflammation and size of the region accompanied by skin discoloration and physical discomfort, characterized by a partial rip of the ligament.

Level 3 – The most severe category of ACL wound resulting from a complete separation of the elastic band. Characterized by severe discomfort, skin discoloration and the inflammation of the tissue in the area. Occasionally cases of level 3 ACL wounds can present with no physical discomfort as the pain-transmitting nerve cells have been destroyed during the ripping of the ligament.

How to Diagnose Anterior Cruciate Ligament?

Only a physician or licensed medical practitioner can confirm a diagnosis of a sprain, partial rip or complete separation of the lower extremity front ligament. A physical exam is ordinarily conducted to confirm or deny the presence of the following symptoms:

  • A lack of full range of motion in and around the knee;
  • Discomfort, inflammation and/or enhanced sensitivity to pain when using the knee;
  • An audible sharp sound akin to popping corn when the knee or lower extremity is flexed;
  • The patient reporting a sensation of having reduced balance or foundational structure, and;
  • Discoloration and tenderness of the tissues in the area which can sometimes only make itself manifest after  a period of time following the onset of the damage.

To proceed further in arriving at an accurate diagnosis of an ACL affliction, medical personnel may use scans performed by a magnetic resonance imaging machine to both locate the source of injury as well as search for additional damage in the area of the lower extremities and knees.

Individuals falling victim to a chronic form of ACL injuries often report that their entire knee joint has become reliably unstable. Often described as prone to buckling or collapsing under pressure accompanied by severe discomfort and tissue inflammation, chronic ACL deficiency may never be fully treated. It is essential to understand, however, that not every individual who sustains one or more injurious events to their knee or lower extremity ligament will automatically be prone to developing a chronic issue with the ligament.

Non-surgical and surgical methods of ACL treatment and recovery

Both trained medical personnel and lay persons have a number of options when it comes to anterior cruciate ligament treatment. Of primary importance is to address the wound when it is first sustained by implementing a total cessation of vigorous movement as soon as possible. In the subsequent hours and days following the onset of damage to the area, the best anterior cruciate ligament treatment is to spend a significant amount of time in the prone position with the lower extremity raised to a slightly higher horizontal plane than the rest of the body.

The application of ice to the area can also be extremely helpful as well as the correct use of special compression bands around the knee in an effort to minimize discomfort and to prevent additional damage to the region. For more intensive therapeutic modalities, it will be necessary to consult with trained medical experts who may prescribe over-the-counter painkillers such as paracetamol or anti-inflammatory drugs like ibuprofen.

Should the damage be too great for the body to naturally heal, it may become required for surgical intervention to help treat the damage to the ligament and/or wounds sustained in and around the knee. Surgeons may intervene in order to construct a new ligament using tissue from similar healthy elastic bands in the leg during a process known by medical experts as an autograft. Should the required cellular tissue come from an outside donor, the correct medical term for this procedure is an allograft.

Another key method of restoring the ligament to full health as well as strengthening and stabilizing the knee is known as physiotherapy. Depending on the level of damage sustained to the area, physiotherapy may be implemented before and after surgical intervention. Should surgical intervention be necessary, doctors will likely prescribe crutches for the patient in order to improve mobility while reducing further stress on the damaged tissues.

Of particular benefit for this type of injury are physiotherapy techniques known as open and closed chain flexes. Flexion exercises of the open type may range from seated leg extensions to leg curls or bench presses. Flexion exercises of the closed type are often similar to lunges and squats. Of paramount importance is to never self-initiate a series of physiotherapy movements without the express consent of a licensed medical practitioner.

Due to the severity and complex nature of damage to this particular ligament, there are a number of complications that may arise for anyone who has sustained an ACL injury. A partial list of risk factors following the reception of damage to the front lower extremity ligament include:

Nerve damage – This can be localized to the knee area or include severe nerve damage all along the breadth and width of the lower extremity;

Vascular damage – If the knee or surrounding bones travel beyond their biological limits as the result of trauma sustained to the area, blood vessels can rupture or become inflamed and swollen; and

Avulsion fractures – A specific type of breakage characterized by small shards of bone that dislocate from their original area and travel onward to cause damage throughout the area.

Surgical intervention to repair or speed healing from a ligament injury is fraught with its own risks, a partial list of which includes:

  • The introduction of foreign microbes into the area resulting in an infection;
  • A permanent reduction in the range of motion of the lower extremity;
  • An unsuccessful tendon graft can lead to a chronic lack of stability and fully healthy operation of the knee joint;
  • Deep vein thrombosis secondary to lengthy amounts of time spent prone;
  • Secondary vascular injuries as the direct result of the surgical intervention itself. In some cases, damage sustained to the nerves in the area can lead to an additional burden of discomfort that may be counterproductive for a speedy recovery process.

Depending on the severity of the torquing force to the front lower extremity ligament, recovering from an ACL injury may be effected in as little as six weeks without resorting to surgical intervention or other extreme measures. For a grade two affliction, medical experts counsel that it may require between six weeks and three months before the individual can expect to regain full use of their knee joint without experiencing discomfort. Severe injuries to the front lower extremity ligament may take as many as 16 weeks following surgical intervention for a complete healing to be effected.


In this instance, an athlete was originally diagnosed with minor quadriceps muscle strain and was treated for four weeks, with unsatisfactory results. When he came to our clinic, the muscle was not healing, and the patients’ muscle tissue had already begun to atrophy.

Upon examination using MSUS, we discovered that he had a full muscle thickness tear that had been overlooked by his previous provider. To mitigate damage and promote healing, surgery should have been performed immediately after the injury occurred. Because of misdiagnosis and inappropriate treatment, the patient now has permanent damage that cannot be corrected.

The most important advantage of Ultrasound over MRI imaging is its ability to zero in on the symptomatic region and obtain imaging, with active participation and feedback from the patient. Using dynamic MSUS, we can see what happens when patients contract their muscles, something that cannot be done with MRI. From a diagnostic perspective, this interaction is invaluable.

Dynamic ultrasonography examination demonstrating
the full thickness tear and already occurring muscle atrophy
due to misdiagnosis and not referring the patient
to proper diagnostic workup

Demonstration of how very small muscle defect is made and revealed
to be a complete tear with muscle contraction
under diagnostic sonography (not possible with MRI)


Complete tear of rectus femoris
with large hematoma (blood)


Separation of muscle ends due to tear elicited
on dynamic sonography examination

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