An ACL injury is a common knee injury that occurs when the ACL, a ligament that connects the thigh bone to the shin bone, is stretched or torn. There are several grades of ACL injury, with grade 1 being the mildest. It is characterized by a small tear or stretching of the ligament, resulting in mild pain, swelling, and instability in the knee. Sudden twisting or bending motion often causes this injury. It is commonly seen in sports that involve cutting and pivoting movements, such as soccer, basketball, and football. Treatment for a grade 1 ACL injury typically involves physical therapy, bracing, and rest, intending to restore the knee’s strength, flexibility, and stability. Surgery may sometimes be recommended if the symptoms persist or the knee remains unstable.

Risk factor for ACL grade 1 injury

Several risk factors[1][2][3][4] increase the likelihood of a grade 1 ACL injury, including.

  1. Gender: Female athletes have a higher risk of ACL injury than male athletes, possibly due to differences in muscle strength, ligament laxity, and hormonal levels.
  2. Hormonal changes: changes in hormonal levels, such as during the menstrual cycle, may increase the risk of ACL injury.
  3. Neuromuscular control: Poor muscle control, balance, and coordination can increase the risk of ACL injury.
  4. Training and conditioning: Lack of proper training and conditioning, such as stretching and strengthening exercises, can increase the risk of injury.
  5. Playing surface: playing on hard or uneven surfaces can increase the risk of injury.
  6. Previous injury: A history of a knee injury, especially an ACL injury, increases the risk of future injury.
  7. Overuse: overuse of the knee joint, such as playing sports or performing exercises that involve repetitive pivoting or cutting motions, can increase the risk of ACL injury.

These factors may be modifiable and can be addressed through proper training, conditioning, and injury prevention strategies.

Causes of ACL grade 1 injury

The most common cause of a grade 1 ACL injury is a sudden twisting or bending knee motion, such as when landing from a jump or changing direction rapidly. Other causes can include:

  1. Direct contact: collision with another player or object can cause an ACL injury.
  2. Overuse: repetitive motions that stress the knee, such as running or jumping, can cause the ligament to become tired and more susceptible to injury.
  3. Poor mechanics: poor technique or form when performing specific movements can increase the risk of injury.
  4. Lack of muscle control: poor muscle control, balance, and coordination can increase the risk of ACL injury.
  5. Fatigue: muscle fatigue can make the knee joint less stable and more susceptible to injury.
  6. Poor conditioning: lack of proper stretching and strengthening exercises can increase the risk of injury.
  7. Hormonal changes: hormonal changes can cause the ligaments to be more relaxed and increase the risk of injury.

It’s important to note that the same factors cause not all ACL injuries and that a combination of various factors can lead to an ACL injury.

Prevention from ACL grade 1 injury

Several steps can be taken to reduce the risk of a grade 1 ACL injury, including.

  1. Proper training and conditioning: A comprehensive training and conditioning program that includes exercises to improve muscle strength, flexibility, and balance can help prevent ACL injuries.
  2. Good technique: learning and practicing a proper method for sports and exercises can help reduce the risk of injury.
  3. Warm-up and cool-down: adequate warm-up and cool-down before and after physical activity can help prevent injury.
  4. Injury prevention programs: specific programs such as FIFA11+ or PEP (Prevent injury, Enhance Performance) can effectively reduce the risk of ACL injury.
  5. Gradual progression: Gradually increasing the intensity and duration of physical activity can help the body adapt and reduce the risk of injury.
  6. Proper equipment: Proper shoes and appropriate playing surfaces can help prevent injury.
  7. Recovery: proper recovery after an injury is essential to help prevent future injuries.

It’s also important to note that not all injuries can be prevented and can happen even with proper prevention measures. If damage does occur, it is crucial to seek prompt medical attention and follow an appropriate treatment and rehabilitation plan.

The treatment plan for ACL grade 1 injury

The treatment plan for a grade 1 ACL injury typically includes the following steps:

Rest and Ice: to reduce pain and inflammation in the knee.

Physical Therapy: to regain strength and flexibility in the knee and help prevent further injury. A physical therapist will work with the patient to develop an individualized rehabilitation plan.

Physical Therapy

Bracing: A brace may be worn to provide support and stability to the knee.

Return to activity: Gradual return to physical activity, such as walking, biking, or swimming, as well as sport-specific training under the guidance of a physical therapist.

Surgery: Surgery is generally not recommended for a grade 1 ACL injury, as the ligament will typically heal independently with proper rehabilitation.

It is important to note that the treatment plan may vary depending on the severity of the injury, the patient’s age, and their level of physical activity. A physiotherapist or orthopedic doctor would be best placed to make a personalized treatment plan.

A grade 1 ACL injury is a mild strain or tear of the anterior cruciate ligament in the knee. The treatment for this type of injury typically involves a combination of rest, ice, physical therapy, bracing, and a gradual return to physical activity. Surgery[5][6] is generally not recommended for a grade 1 ACL injury, as the ligament will typically heal independently with proper rehabilitation. It’s essential to follow the treatment plan recommended by a physiotherapist or orthopedic doctor and to be patient with the healing process. Remember, returning to physical activity too soon or not following the proper rehabilitation protocol can increase the risk of re-injury or worsening the injury.


1. Markolf KL, Mensch JS, Amstutz HC. Stiffness and laxity of the knee–the contributions of the supporting structures. A quantitative in vitro study. J Bone Joint Surg Am. 1976;58:583–594.


2. Griffin LY, Albohm MJ, Arendt EA, Bahr R, Beynnon BD, Demaio M, Dick RW, Engebretsen L, Garrett WE, Hannafin JA, Hewett TE, Huston LJ, et al. Understanding and preventing noncontact anterior cruciate ligament injuries: a review of the Hunt Valley II Meeting. 2005. pp. 1512–1532.


3. Bates NA, McPherson AL, Rao MB, Myer GD, Hewett TE. Characteristics of inpatient anterior cruciate ligament reconstructions and concomitant injuries. Knee Surg Sports Traumatol Arthrosc. 2014:Epub ahead of print.


4. Eberhardt C, Jäger A, Schwetlick G, Rauschmann MA. [History of surgery of the anterior cruciate ligament] Orthopade. 2002;31:702–709


5. Zysk SP, Refior HJ. Operative or conservative treatment of the acutely torn anterior cruciate ligament in middle-aged patients. A follow-up study of 133 patients aged 40 and 59 years. Arch Orthop Trauma Surg. 2000;120:59–64.


6. Herbort M, Lenschow S, Fu FH, Petersen W, Zantop T. ACL mismatch reconstructions: influence of different tunnel placement strategies in single-bundle ACL reconstructions on the knee kinematics. Knee Surg Sports Traumatol Arthrosc. 2010;18:1551–1558.


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