Everything you need to know about ACL injury

Before we start about ACL injury we should have idea about knee joint, how it is formed and how it helps in our functional activities……..

Knee joint is the largest and most complex joint of the body.

Type- saddle type of joint

Articular surfaces –

  • The condyles of the femur
  • The patella
  • The condyles of tibia

Important ligaments : 

  1. Anterior cruciate ligament(ACL)
  2. Posterior cruciate liagament(PCL)
  3. Medial collateral ligament(MCL)
  4. Lateral collateral ligament (LCL)

Other structures includes medial meniscus, lateral meniscus,oblique popliteal lig. , arcuate popliteal lig. , ligamentum patellae  etc .

mayfair.com.bd acl-injury

What is an ACL Injury?

Injuries to the ACL are relatively common knee injuries among athletes. They occur most frequently in those who play sports involving pivoting (e.g. football, basketball, netball, soccer, European team handball, gymnastics, downhill skiing). They can range from mild (such as small tears/sprain) to severe (when the ligament is completely torn). Both contact and non-contact injuries can occur, although non-contact tears and ruptures are most common. It appears that females tend to have a higher incidence rate of ACL injury than males, that being between 2.4 and 9.7 times higher in female athletes competing in similar activities.

Mechanisms of Injury / Pathological Process 

Three major types of ACL injuries are distinguished

  • Direct Contact
  • Indirect Contact
  • Non-Contact

Most common are the non-contact injuries, caused by forces generated within the athlete’s body while most other sport injuries involve a transfer of energy from an external source. Approximately 75% of ruptures are sustained with minimal or no contact at the time of injury. A cut-and-plant movement is the typical mechanism that causes the ACL to tear, that being a sudden change in direction or speed with the foot firmly planted. Rapid deceleration moments, including those that also involve planting the affected leg to cut and change direction, have also been linked to ACL injuries, as well as landing from a jump, pivoting, twisting, and direct impact to the front of the tibia.

Women are three times more prone to have the ACL injured then men, and is thought to be due to the following reasons:

  • Smaller size and different shape of the intercondylar notch
  • Wider pelvis and greater
  • Greater ligament laxity
  • Shoe surface interface
  • Neuromuscular factors
  • A wider pelvis requires the femur to have a greater angle towards the knee, lesser muscle strength provides less knee support, and hormonal variations may alter the laxity of ligaments.
mayfair.com.bd acl-injury

Biomechanics of Injury

As 60-80% of ACL injuries occur in non-contact situations, it seems likely that appropriate prevention efforts are warranted. Cutting or sidestep maneuvers are associated with dramatic increases in the varus-valgus and internal rotation moments. The ACL is placed at greater risk with both varus and internal rotation moments. The typical ACL injury occurs with the knee externally rotated and in 10-30° of flexion when the knee is placed in a valgus position as the athlete takes off from the planted foot and internally rotates with the aim of suddenly changing direction (as shown by the figure below).The ground reaction force falls medial to the knee joint during a cutting maneuver and this added force may tax an already tensioned ACL and lead to failure. Similarly, in landing injuries, the knee is close to full extension. High-speed activities such as cutting or landing maneuvers require eccentric muscle action of the quadriceps to resist further flexion. It may be hypothesized that vigorous eccentric quadriceps muscle action may play a role in disruption of the ACL. Although this normally would be insufficient to tear the ACL, it may be that the addition of valgus knee position and/or rotation could trigger an ACL rupture.

Characteristics/Clinical Presentation

  • Occurs after either a cutting maneuver or one leg standing, landing or jumping
  • There may be an audible pop or crack at the time of injury
  • A feeling of initial instability which may be masked later by extensive swelling
  • Episodes of “giving way” especially on pivoting or twisting motions. Patient has a “trick knee” and a predictable instability
  • A torn ACL is extremely painful, particularly immediately after sustaining the injury
  • Swelling of the knee, usually immediate and extensive, but can be minimal or delayed
  • Restricted movement, especially an inability to fully extend
  • Possible widespread mild tenderness
  • Tenderness at the medial side of the joint which may indicate cartilage injury

Associated Injuries 

  • Injuries to ACL rarely occur in isolation. The presence and extent of other injuries may affect the way in which the ACL injury is managed.

Meniscal lesion

Over 50% of all ACL Ruptures have associated Meniscal injuries. If seen in combination with a Medial Meniscus Tear and MCL Injury, it is called O’Donohue’s Triad which has 3 components:

  • Anterior Cruciate Ligament (ACL) Tear
  • Medial Collateral Ligament(MCL) Tear
  • Meniscal Tear

Diagnostic Procedures

An exact diagnosis can be made by the following procedures:

  PHYSICAL EXAMINATION which includes the following tests:

  • Lachman Test
  • Anterior Drawer Test of the Knee
  • Pivot shift


  • Radiographs of the knee should be performed when an ACL tear is suspected, including AP (anterior to posterior) view, lateral view, and patellofemoral projection. The standing AP weight-bearing view provides a way of evaluating the joint space between the femur and tibia. It also allows for measurement of the notch width index which provides important predictive values for ACL tears.
mayfair.com.bd acl-injury

Physiotherapy treatment protocol :

The major goals of rehabilitation of the ACL-injured knee

  • Gain good functional stability
  • Repair muscle strength
  • Reach the best possible functional level
  • Decrease the risk for re-injury
  • Closed kinetic chain exercises (CKC) and Open kinetic chain exercises (OKC) play an important role in regaining muscle (quadriceps, hamstrings) strength and knee stability.
  • Closed kinetic chain exercises have become more popular than Open kinetic chain exercises in ACL rehabilitation. Clinicians believe that CKC exercises are safer than OKC exercises because they place less strain on the ACL graft. Besides, they also believe that CKC exercises are more functional and equally effective as OKC exercises.

Before Surgery 

  • RICE and electrotherapy can be applied during several weeks ahead of the surgery in order to reduce swelling and pain, to attempt full range of motion and to decrease joint effusion. This will help the patient to regain better motion and strength after the surgery
  • Pre-op therapy should encourage strengthening of the quadriceps and hamstrings.

After Surgery

  • Week 1
    • Regular icing and elevation are used to reduce swelling. The goal is full extension and 70 degrees of flexion by the end of the first week. The use of a knee brace and crutches are imperative.
    • Multidirectional mobilizations of the patella should be included for at least 8 weeks. Other mobilization exercises in the first 4 weeks are passive extension of the knee (no hyperextension) and passive and active mobilization towards flexion. Strengthening exercises for the calf muscle, hamstring and quadriceps (vastus medialis) can be performed.
  • Week 3-4
    • The patient must try to genuinely increase the stance phase in an attempt to walk with one crutch. With good hamstring/quadriceps control, the use of crutches can be reduced earlier.
  • Week 5
    • The use of the knee brace is progressively reduced.Passive mobilizations should normalize motility but flexion should not yet be thorough. 9 Tonification of hamstrings and quadriceps (vastus medialis) can start in close chain exercises. The exercises should be started on light intensity (50% of maximum force) and progressively increased to 60-70%. The closed chain exercises should be built from less responsible positions (bike, leg presses, step) to more congested starting positions (ex.squad). The progress of the exercise depends on pain, swelling and quadriceps control. Proprioception and coordination exercises can start if the general strength is good. This includes balance exercises on boards and toll.
  • Week 10
    • Forward, backward and lateral dynamic movements can be included as well as isokinetic exercises.
  • Month 3
    • After 3 months, patient can move on to functional exercises as running and jumping. As proprioceptive and coordination exercises become heavier, quicker changes in direction are possible. To stimulate coordination and control through afferent and efferent information processing, exercises should be enhanced by variation in visible input, surface stability (trampoline), speed of exercise performance, complexity of the task, resistance, one or two-legged performance, etc.
  • Month 4-5
    • Final goal is to maximize endurance and strength of the knee stabilizers, optimize neuromuscular control with plyometric exercises and to add the sport-specific exercises. Acceleration and deceleration, variations in running and turning and cutting manoeuvers improve arthrokinetic reflexes to prevent new

Whiplash Injury

Whiplash is a neck injury caused by sudden movement of head. It is commonly happened during car driving because of rear-end car accidents. But whiplash can also

Read More »
Call Now Button