ACL Injury

The ACL is a unique structure and one of the most important ligaments to knee stability.

The anterior cruciate ligament extends superiorly, posteriorly, and laterally, twisting on itself as it extends from the tibia to the femur.

ACL injuries are common among athletes because their activities involve movements that put a lot of stress on the knee.


  • The ACL is considered intra-articular yet extrasynovial because of the posterior invagination of the synovial membrane.
  • The ACL consists of two functional bundles- the antero-medial (A-M) and posterolateral (P-L) bundles, named for their position on the tibia.
  • The tensile strength of the ACL is equal to that of the knee collaterals, but it is half that of the PCL.


  • It serves as a primary restraint to anterior translation of the tibia relative to the femur.
  • It provides significant mechanical stabilization to the knee joint by preventing excessive hyperextension, as well as tibial rotation and anterior tibial translation while in flexion.
  • The normal ACL is capable of microscopic adjustments to internal stresses over time, thus influencing the laxity, stresses, and kinematics of the joint.
  • The anteromedial bundle is tight in both flexion and extension, limits anterior translation, and helps to stabilize medial and lateral rotation, whereas the posterolateral bundle is tight in low flexion angles (closer to extension) and medial rotation. It limits anterior translation, hyperextension, and rotation.

Grade of injury-

  • Grade I (Minimal tear)-
  1. Local tenderness
  2. No instability
  3. Stress test causes pain
  4. Joint separation upto 5mm
  • Grade II (Moderate tear)
  1. Localized oedema
  2. Minimal instability
  3. Extremely painful Stress test
  4. Joint separation between 5mm to 10mm.
  • Grade III (Complete tear)
  1. Marked joint instability
  2. Joint separation of more than 10mm.

Mode of Injury-

  • Injury to the anterior cruciate ligament commonly results from a fall from height with the knee in flexion and the body rotating on the stationary foot. 
  • Hyperflexion or hyperextension with internal rotation of the tibia.


  • Gait observation-

ACL injury produces biomechanical deviation of gait. Generally a decrease in flexion during the mid-stance phase is seen.

  • Lachman test-
  1. Patient position – patient is supine, with knee in 20degrees of flexion. Examiner stands on the side of the injured knee and pulls the tibia anteriorly.
  2. Observation- test is positive if there is excessive anterior translation of proximal tibia and a lack of firm and point indicates ACL injury. 
  • Anterior drawer test-
  1. patient position- patient is supine with knee flexed to 90degree examiner attempts to pull tibia anteriorly.
  2. Observation – result is positive if tibia is displaced anteriorly on the femur and the severity is tested according to range of displacement. 
  • Pivot shift test
  1. Patient position – knee is positioned in 30 degrees of flexion. Examiner places one hand under the heel and the other on the lateral aspect of the proximal tibia, then applies valgus stress. The knee is then brought into extension.
  2. Observation – in ACL disruption the lateral tibial plateau is in the anatomic position when the knee is flexed and subluxed anteriorly during extension.  
  • MRI


Physiotherapy management

Acute Stage:

RICE protocol with immobilization for 24-48 hours.

  • Cryotherapy (15 minutes per hour) at the acute stage of injury.
  • Crepe bandage with limb elevated. 
  • Modalities – 
  • Daipulse 
  • Ultrasound 
  • IFT (Interferential Therapy) 
  • TENS (Transcutaneous Electrical Nerve Stimulation)
  • Quadriceps isometric (5 minutes/1-2 hours) to avoid quadriceps wasting , start cautiously and work your way up to a maximum sustained contraction.
  • Active movements of nearby joints-
  • When the leg is immobilized in POP (plaster of Paris), move ankles and toes vigorously to maintain blood supply.
  • SLR with assistance ( straight Leg Raised )
  • Hip Abduction (Abduction of the Hip)
  • If the cast is not recommended, start with a little range of self-assisted relaxed gentle knee swinging.

Subacute Phase : 

RICE protocol with immobilization for 3-6 weeks.

  • Quadriceps Isometrics.
  • Begin mobilization by having the patient sit on the edge of the bed or table (couch) with the injured limb supported by the sound limb.
  • The patient is guided through a small range of gentle rhythmic knee flexion and extension in a comfortable self-assisted manner.
  • Continuous Passive motion (CPM) exercises to aid active or active assisted movements as soon as practicable.
  • Knee flexion range of motion can be greatly improved with self-assisted relaxed passive stretching.
  • Heel drag sessions are important to achieve flexion and maintain range.
  • To achieve free mobility, relaxed knee swinging should be made faster with a larger arc of movement.
  • Straight Leg Raised – Begin with small, steady repetitions of little, rhythmic motions.
  • By progressively increasing the weight or resistance, you should be able to achieve your goals.
  • SLR can be progressed along with addition of Straight Leg Abduction (SLA).
  • Prone SLR.
  • Knee flexion – Knee flexion exercises should be performed on a static bicycle(in both clock and anti-clockwise directions) as well as in a prone position.
  • Progressive Resistance exercises (PRE) for further strengthening.
  • Stair climbing initiated small steps up and down the stairwell.
  • Squats against the wall.

Chronic Injury: 

RICE protocol with immobilization for 6-8 weeks.

  • Even chronic ligament injuries respond well to a regimen of knee strengthening and hamstring stretching exercises, but knee flexion should be protected with a knee brace during certain activities.
  • Patients with chronic ligament instability may show weakness of the hip muscle and hamstring, which should be tested and strengthening exercises to reduce muscle groups should be included in the treatment whenever necessary.

Surgical management-

ACL surgery is a technique in which a damaged ligament in the knee joint is replaced, done when conservative management fails or in case of complete tear generally.

1.) Percutaneous ACL Repair –

Without surgery, 70% of ACL rupture can be repaired. Our goal is to save, not replace the ACL. Individuals who are considering surgery for a partial or complete non-retracted ACL tear should consider the percutaneous ACL repair method. Orthobiologics therapies concentrate and focus on the body’s own healing chemicals at the exact spot of the injury, allowing them to rebuild and repair damage to the ACL. This method promotes natural, effective healing without the use of surgery.

2.) ACL Tear Repair With Fiber Tape Internal Brace-

Most surgeons remove all of the residual ACL tissue during ACL repair, leading to the loss of proprioception, which is critical for knee stability and preventing arthritis so, ACL repair is done with no removal of ACL tissue in intact, only the torn ACL part is repaired which is protected by a fiber tape as internal brace. As a result, your own ACL is restored without causing any tissue loss, so players recover quickly and return to sports and jogging within three months of surgery. He has a lot more confidence in his knee now that his ACL has been repaired and saved. If the ACL avulsion has happened from the femoral end, it can be healed.

3.) Anterolateral Ligament (ALL) Internal Brace- 

ALL is responsible for the knee’s anterolateral rotational stability. Internal bracing of the anterior cruciate ligament (ACL) and ALL strengthens the ligaments and promotes natural healing by protecting them during the healing phase and allowing for early mobilization.

4.) ACL Avulsion Repair –

Arthroscopic ACL avulsion with a tibial spine fracture requires minimally invasive ACL avulsion repair surgery. The goal is to preserve the original ACL rather than to recreate it. With the use of Fiber tape internal brace and tightrope RT, a tibial spine avulsion with ACL is reattached to the tibial plateau. Within three months of surgery, the athlete can return to sports and can run thanks to this improved fracture fixation procedure.

5.) All Inside ACL Reconstruction With Fiber Tape Internal Brace – 

In the majority of cases, we need to reconstruct the ACL because of the ACL tear anatomy.

To protect proprioception, the hamstring tendon is used to reconstruct the new ACL, and a sleeve of the original ACL is left in the knee joint to cover the new tendon. Various implants are used to secure the hamstring tendon to the bones. Fixation with bio screws is one way, but medical research papers and clinical investigations from around the world have shown that bio screw fixation has a 30% failure rate, and the recovery process is extremely painful, taking 8 to 9 months to return to sports and jogging.

Post operative physiotherapy management-

It is divided in 5 phases-

  • Phase 1 (0-2 weeks)
  • Phase 2 (2-4 weeks)
  • Phase 3 (6 weeks- 4 months)
  • Phase 4 (After 4 months)
  • Phase 5 (Return to sports)


  • Immobilization- Immobilized in extension brace.
  • Weight bearing- Weight bearing as tolerated with crutches or walker.
  • Exercises- 
  1. Heel drag
  2. Patellar mobilization
  3. Quadriceps drills
  4. SLR with brace
  5. Functional training (eg- static bicyclining)

Phase 2-

  • Weight bearing-
  1. Patellar tendon graft- Continue extension brace for ambulation but remove for sitting, sleeping and ROM exercises.
  2. Hamstring or allograft- Discontinue brace when quadriceps control is achieved.
  • Exercises-
  1. Mini squats (0-30 degree)
  2. Leg press ( 0- 30 degree)
  3. Toe raise in standing
  4. Phase 2 functional training {Aerobic conditioning, Plyometrics for eccentric muscle training, aquatherapy}

Phase 3- 

  • Continue flexibility exercises appropriate for patients.
  • Advance closed – kinetic chain strengthening ( one leg squats, leg press 0-60 degree)
  • Stairs- step up or step down
  • Functional Training Phase 3 { Aerobic Conditioning, Plyometrics, Running} ( 6-12 weeks)
  • Functional Training Phase 4 {Aerobic Conditioning, Agility training, Plyometrics, Running} ( +12 week)

Phase 4-

  • Progress flexibility and strength training
  • Phase 5 functional training { Advance phase 4 functional training}

Phase – 5

  • Brace-
  • Functional Braces may be recommended by physicians for use during sports for the first 1-2 years after surgery for confidence.
  • Exercises-
  1. Gradual return to sports participation.
  2. Maintenance program for Strength and Endurance.
  3. Agility and sports specific Drills progressed.


  • Mark Dutton ( Dutton’s orthopedic )
  • David J. Magee and Robert C. Manske ( Orthopedic physical assessment)
  • Jayant Joshi and Prakash Kotwal ( Orthopedics and applied physiotherapy)
  • J. Maheshwari and Vikram A. Mhaskar ( Essential orthopedics)
  • S. Brent Brotzman and Kevin E. Wilk ( Clinical orthopedic rehabilitation)