ACL Surgery

Joint Replacement

What is ACL Injury?

The knee is the largest joint in the human body, and proper knee function and health are required for most daily activities. The lower end of the femur (thighbone), the patella (kneecap), and the upper end of the tibia comprise the knee (shinbone). Articular cartilage, a smooth substance that protects and allows the bones to move freely, covers the ends of the three bones and serves as the primary shock absorber. The menisci are two C-shaped cushioning wedges that act as secondary shock absorbers between the femur and the tibia. Large ligaments (tough bands of tissue) help hold the femur and tibia together, preventing excessive movement and thus stabilising the joint.The synovial membrane, a thin lining that releases fluid that lubricates the cartilage, reduces friction within the knee joint, and provides nutrition to the cartilage, covers the lining joint. All of these components work together to ensure proper knee function.

The knee has four primary ligaments that act like strong ropes to hold the bones together and keep the knee stable. They are the anterior and posterior cruciate ligaments, as well as the medial and lateral collateral ligaments.The collateral ligaments are located on the sides of your knee and are in charge of controlling sideways motion and bracing it against unusual movement. Inside your knee joint, the cruciate ligaments form an X, with the anterior cruciate ligament (ACL) in front and the posterior cruciate ligament (PCL) in back. They are in charge of controlling the knee’s forward and backward motion. The ACL runs diagonally through the middle of the knee, preventing the tibia from sliding out in front of the femur and providing rotational stability.

What Causes an ACL Injury?

When the knee is sharply twisted or extended beyond its normal range of motion, an ACL injury occurs. 70% of ACL tears occur as a result of sport participation, with the majority occurring in people aged 15 to 45. The ACL is one of the most commonly injured ligaments in the knee, with noncontact sudden changes in direction with a planted foot or rapid stopping accounting for 70% of ACL injuries. Female athletes are two to eight times more likely than male athletes to sustain an ACL injury, and athletes who sustain an ACL injury are more likely to tear or injure the other ACL. Basketball, soccer, football, volleyball, and skiing are all high-risk sports.

Symptoms of an ACL Injury

Individuals who sustain an ACL injury typically exhibit the following signs and symptoms:

At the time of the injury, you may have heard or felt a pop.

Severe pain, difficulty walking, and inability to resume normal activities immediately following the injury

Swelling around the knee joint begins immediately and worsens for several hours after the injury.

With weight bearing, there is a sensation of instability and bucking (giving way) in the knee.

A restricted or limited range of motion

Because this pain can be severe, most people who injure their ACL seek immediate medical attention, especially if they intend to return to sport or activity soon. However, if the swelling and pain are ignored, they may resolve on their own. The knee may feel relatively normal during daily activities, but it is usually very unstable when returning to sport. Returning to sports after an ACL injury increases the risk of further damage to the meniscus of the knee.

How is ACL Injury Diagnosed?

ACL injuries are typically diagnosed using a combination of patient history, physical examination, and imaging studies. The doctor will examine the knee and compare it to the uninjured knee in terms of range of motion, stability, swelling, tenderness, and overall strength. Often, the diagnosis can be made based solely on a physical exam, especially if the ACL is completely ruptured; however, the physician will usually order X-rays to rule out any additional damage and may order an MRI scan to determine the extent of the damage.

Surgery for ACL Injury

Treatment for an ACL injury or tear will vary depending on the severity of the damage, the individual’s age, and the level of activity they wish to resume. Younger athletes participating in agility-based sports will almost certainly require surgery to safely return to the same level of sports, whereas older, less active individuals may be able to return to a less active lifestyle without surgery.

Because an ACL injury is considered a sprain, the self-care RICE approach is used for immediate treatment of an ACL injury:

Rest: Walking will be painful, so avoid putting pressure on the injured knee and limit activity while the inflammation is present.

Ice: should be applied for 10 to 20 minutes no more than once per hour for the first 48 to 72 hours, or until the swelling subsides. It is strongly recommended that you use a barrier, such as a towel, to protect your skin. Heat should be avoided while the inflammation is active; once the swelling has subsided, heat can help relieve pain.

Compression – Using a compressing wrap can help reduce swelling significantly. Make sure the wrap is snug; however, if there is numbness, tingling, or swelling above or below the wrap, it is likely too tight and should be loosened.

Elevation- Raising the knee above the heart level for a few hours each day can significantly help to reduce swelling.

Once the initial swelling has subsided with the RICE approach, the patient and physician must decide on the best course of action. A torn ACL will not heal without surgery; however, non-operative treatments may be sufficient for elderly patients with very low activity levels. These treatments may include a brace placed on the affected knee to provide stability, crutches to keep weight off the affected knee, or a physical therapy programme in which the physical therapist will provide specific exercises to restore function to the knee and strengthen the surrounding muscles that support it.

The surgical procedure to repair an ACL tear requires the ligament to be rebuilt. Because a torn ACL cannot be sutured or sewn back together, it is usually replaced with a piece of tendon harvested from another source.

Small incisions are made around the joint to insert surgical instruments and the arthroscope (a small camera), and the image is transmitted to a video monitor, allowing the doctor to see inside the joint. The torn ACL is completely removed using surgical instruments. The graft will then be prepared and inserted.


Regardless of the treatment method used, patients must go through a rehabilitation programme that includes physical therapy exercises that are essential for strengthening leg muscles and regaining knee strength and motion. Because each patient is different, the therapy programme will be tailored to his or her level of pain, extent of injury, and desired level of activity. Physical therapy is divided into phases for patients who have had surgery:

Phase 1: Motion Range This phase will begin with restoring motion to the joint and surrounding muscles. This phase begins immediately following surgery and lasts approximately six weeks.

Phase 2: Stabilization This phase is intended to protect the newly formed ligament and beings following the first phase.

Low-impact cardio exercises such as an elliptical trainer or stair-stepper can be started around eight weeks after surgery, with weight training beginning two to three months later, but only under the supervision of a physical therapist.

Phase 3: Sport-Specific Exercises During this phase, the physical therapist will collaborate with the individual to design a personalised rehabilitation programme that will prepare them to return to their desired sport or level of activity. Running is typically permitted between three and six months, with pivoting and twisting activities permitted between four and nine months.

Phase 4: Return to Sport The final phase involves returning to sport under close supervision, which usually takes six to twelve months.

Most patients return to normal day-to-day activities within three to four months; however, athletic activities and regaining strength can take up to a year; this is something to discuss with both the physician and the physical therapist. Finally, the physician and physical therapist will collaborate to determine the best time for the individual to return to their preferred sport. Careful planning will be used to return the individual to their preferred lifestyle while minimising the risk of ACL re-tear.