Anterior Cruciate Ligament injury; types causes and types

 Ligament Injuries

The anterior cruciate ligament (ACL) is the most commonly injured ligament. Often more than one ligament is damaged as the result of a single injury.

Anterior Cruciate Ligament injury


Anterior Cruciate Ligament

Anterior cruciate ligament (ACL) injuries occur from both contact and noncontact mechanisms. The most common contact mechanism is a blow to the lateral side of the knee resulting in a valgus force to the knee. This mechanism can result in injury not only to the ACL but to the medial collateral ligament (MCL) and the medial meniscus as well. This injury is termed the “unholy triad” injury because of the frequency of these three structures being injured from a common blow. The most common noncontact mechanism is a rotational mechanism in which the tibia is externally rotated on the planted foot. Literature supports that this mechanism can account for up to 78% of all ACL injuries. The second most common noncontact mechanism is forceful hyperextension of the knee. With prolonged ambulation on a knee that has a deficient ACL, the secondary restraints (lateral collateral ligament and posterolateral joint capsule) are stressed and become lax, and the individual may develop a “quadriceps avoidance gait.”The quadriceps avoidance gait in ACL deficient knees was originally documented and described by Berchuck and collegues  as a reduction in the magnitude of the flexion moment about the knee during the limb loading phase of gait due to the patient’s effort to reduce contraction of the quadriceps.

Posterior Cruciate Ligament

The posterior cruciate ligament (PCL) is most commonly injured by a forceful blow to the anterior tibia while the knee is flexed, such as a blow to the dashboard or falling onto a flexed knee.

Medial Collateral Ligament

Isolated injuries to the medial collateral ligament (MCL) can occur from valgus forces being placed across the medial joint line of the knee. Whereas most injuries to the ACL and PCL are complete tears of the ligament, injuries to the MCL can be partial or incomplete and are graded utilizing a I, II, III grading classification of ligament injuries

Lateral Collateral Ligament

Injuries to the lateral collateral ligament (LCL) are infrequent and usually result from a traumatic varus force across the knee. It is not uncommon that more than one ligament, joint capsule, and sometimes the menisci are damaged as the result of a single injury.

Ligament Injuries in the Female Athlete

With an increase in the number of female athletes since the passage of Title IX in 1972, a concurrent increase in the number of injuries to female athletes has been seen, most significantly an increase in the number of knee injuries. What is interesting is that when injury to the ACL is sustained in a noncontact manner, a woman is three times more likely to tear the ACL than a man. With the increased number of noncontact ACL injuries in female athletes being reported, the American Academy of Orthopaedic Surgeons published a consensus paper examining the risk factors and prevention strategies of noncontact ACL injuries.  In addition, results from a research retreat on “ACL Injuries—The Gender Bias” were published in the Journal of Orthopaedic and Sports Physical Therapy. Risk factors fall into four major categories:

environmental, anatomical, hormonal, and biomechanical.

Environmental factors center on the use of prophylactic knee braces to prevent knee injuries and a shoe-tosurface interface that may improve performance but may also increase the risk of injury.

Anatomical risk factors include femoral notch size, ACL size, and lower extremity alignment. Insufficient data relating to each of these factors have resulted in an incomplete understanding of the influence of these factors at this time.

Hormonal differences between males and females have also been postulated to be one possible factor related to the increased incidence of female ACL injuries. In 1996, hormone receptor sites for estrogen and progesterone were found in the ACL of humans. Since that time, research has been conducted to study the effects of such hormones on the mechanical properties of the ACL and other musculoskeletal tissues. To date, however, results of multiple studies differ in their conclusions.

Biomechanical risk factors summarized by the consensus panel included the effect of the total chain (trunk, hip, knee, and ankle) on ACL injuries, awkward or improper dynamic body movements, deceleration and change of direction, and neuromuscular control of the joint.

Common Impairments and Functional Limitations/Disabilities

• Following trauma, the joint usually does not swell for several hours. If blood vessels are torn, swelling

is usually immediate.

• If tested when the joint is not swollen, the patient feels pain when the injured ligament is stressed.

• If there is a complete tear, instability is detected when the torn ligament is tested.

• When swollen, motion is restricted, the joint assumes a position of minimum stress (usually flexed ), and inhibition (shut down) of the quadriceps muscle occurs.

• When acute, the knee cannot bear weight, and the person cannot ambulate without an assistive device.

•With a complete tear, there is instability, and the knee may give way during weight bearing

Ligament Injuries: Nonoperative Management

Acute sprains and partial ligament tears of the knee can be treated conservatively with rest, joint protection, and exercise. After the acute stage of healing, exercises should be geared toward regaining normal ROM, balance control, normalization of gait, and strengthening of muscles that support and stabilize the joint during functional activities. The degree of instability with ligament tears affects the demands the patient can place on the knee when returning to full activity

Nonoperative Management:

Maximum Protection Phase

Follow the principles described for an acute joint lesion If possible, examine before effusion sets in. Utilize cold and compression with rest and elevation. Protect the joint during ambulation with use of crutches; partial weight bearing as tolerated. Teach safe transfer activities to avoid pivoting on the involved extremity. Initiate quadriceps-setting exercises. The knee may not fully extend for end-range muscle-setting exercises, so begin the exercises in the range most comfortable for the patient. As the swelling decreases, initiate ROM within tolerance and the swelling decreases, examine the patient for impairments and functional losses. Initiate joint movement and exercises to improve muscle performance, functional status, and cardiopulmonary conditioning.

Improve Joint Mobility and Protection

Joint mobility. Use supine wall slides  patellar mobilizations, and stationary cycling; encourage as much movement as possible. Unless there has been an extended period of immobilization, there should be minimal need to stretch contractures.

Protective bracing

 Bracing may be necessary for weightbearing activities to decrease stress to the healing ligament or to provide stability where ligament integrity has been compromised. Bracing can be one of two types: rangelimiting postoperative type braces that are used to protect  healing tissues and discarded during later phases of rehabilitation or functional braces that are used during rehabilitation and also when returning to functional activities. The patient must be advised to modify activities until appropriate stability is obtained.

Improve Muscle Performance and Function Strength and endurance

 Initiate isometric quadriceps and hamstring exercises and progress to dynamic strength and muscular endurance training. Neuromuscular control is compromised when stabilizing muscles fatigue. Utilize both open-chain and closed-chain resistance. Reinforce quadriceps contractions with high-intensity electrical stimulation if there is an extensor. Progress muscular endurance and strengthening exercises using partial squats, step-ups, leg press, and heel-raises Emphasize neuromuscular control with stabilization and perturbation training in weight-bearing positions.

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