Anterior cruciate ligament reconstruction (ACL reconstruction)

Last updated date: 06-Jul-2023

Originally Written in English

Anterior cruciate ligament reconstruction (ACL reconstruction)


One of the two cruciate ligaments that help to stabilize the knee joint is the anterior cruciate ligament. It is a strong band of connective tissue and collagenous fibers that extends posteromedially from the anteromedial aspect of the tibial plateau's intercondylar region to the lateral femoral condyle. It is the most commonly injured ligament in the knee, and it is most commonly seen in football, soccer, and basketball players.

The ACL and the PCL form a cross (or a "x") within the knee, preventing excessive forward or backward motion of the tibia relative to the femur during flexion and extension. The ACL also provides rotational stability to the knee when it is stressed in Varus or valgus. ACL sprains and tears are common knee injuries, with 100,000 to 200,000 cases reported each year in the United States.


Non operative treatment 

Nonoperative treatment is typically reserved for those with low functional demands, the type and severity of ACL tear, the time of injury, and subsequent evaluation. An orthopedist and physical therapist will continue to monitor and treat them, which will only improve their functional status and stability post-injury. It is worth noting that approximately half of the patients who initially choose the non-operative pathway will later choose surgical repair.

Non operative treatment is preferred when the patient:

  • Is older than 35 years old
  • Has no or minimal anterior tibial subluxation
  • Has no additional intra-articular injury
  • Is not highly active


Operative treatment

ACL reconstruction Operative treatment

Many factors influence the decision to undergo surgical treatment, including the patient's baseline level of physical activity, functional demands, age, occupation, and other associated injuries, if present. Athletes and people who are younger and more active are more likely to choose surgical repair and reconstruction. Other surgical repair/reconstruction candidates include those who have significant knee instability and/or multiple knee structures that have been injured.

A tissue graft is typically treated surgically. According to a recent systematic review, 81% of those treated with ACL reconstruction returned to some athletic activity, 66% returned to their pre-injury level of competition, and 55% of high-level athletes returned to normal play and competition.

Despite this, it has been reported that 90 percent of those who undergo surgical repair return to near-normal functioning. External factors, such as fear of reinjury, may be secondary to the factors that contribute to a lower percentage of return to play.


Why would I need an ACL reconstruction?

ACL reconstruction may be an option for you if you have an ACL injury and your knee is unstable (it gives way). Not every ACL injury necessitates surgery. Your doctor or surgeon will go over your treatment options with you and explain which one is best for you. However, there are some circumstances in which surgery is more likely to be recommended. These include the following:

  • Play high-level sports that require a lot of twisting and turning – such as football or basketball – and want to get back into it 
  • Have a very physical or manual job, such as being a firefighter, police officer, or working in construction 
  • Have damage to other parts of your knee that could also be repaired with surgery


Anterior cruciate ligament reconstruction

Anterior cruciate ligament reconstruction

Reconstructive surgery aims to restore stability and maintain full active ROM. The normal ACL provides functional stability by resisting both anteroposterior translation and rotational subluxation.

Reconstruction techniques differ, as do the graft materials available. Surgical management options can vary depending on the patient's symptoms as well as their level and type of activity. Specifically, if their sport requires rotating movements. Conservative management is an option, but the long-term outlook isn't as promising.

For ACL reconstruction, there is no gold standard. Each surgeon uses a different technique and has a different preference. More recent techniques are producing results that are still inconclusive in terms of long-term outcomes. Arthroscopy vs. open surgery, intra vs. extra-articular reconstruction, femoral tunnel placement, number of graft strands, single vs. double bundle, and fixation methods are all different techniques.

Extra-articular reconstruction has been used to address pivotal shift, and it has been shown to have greater effects than intra-articular reconstruction, but it lacks residual stability. Intra-articular became the preferred method, but it does not restore normal knee kinematics. The double bundle is thought to be more anatomical and supportive, particularly during rotary loading. It can replicate anteriomedial and posteriolateral bundles with the help of the gracilis and semitendonosis tendons.

In the long run, the single bundle method (of the AM portion) is said to have rotator instability. To achieve long-term stability, all ligaments and capsular restraints must be isometric within a full range of motion. The ACL's isometric function is achieved through the arrangement of its two fiber bundles (anteriomedial and posteriolateral) and their attachments.

The ACL is made up of bundles of individual fibers that form a spiral configuration and fan out over large attachment areas. Ligament attachment sites should not be changed during reconstruction due to their complex structure.

There are two different techniques used for ACL reconstruction:

  • Extra-articular
  • Intra-articular


Extra-articular reconstruction

Extra-articular procedures for anterior tibial subluxation were commonly used in the 1970s and 1980s to eliminate any pivot shift. However, it has fallen out of favor due to residual instability and the subsequent development of degenerative changes. Extra-articular reconstruction has been used alone or in conjunction with intra-articular reconstruction. Although intra-articular reconstruction has become the preferred option, it does not completely restore knee kinematics.

Because intra-articular reconstruction creates a static restraint, it was usually accompanied by connecting the lateral femoral epicondyle to Gerdy's tubercle, with the collagenous restraint lying parallel to the intra-articular course of the ACL. This also avoids the issue of inadequate blood supply to intra-articular reconstructions. The iliotibial band or tract, which connects the lateral femoral epicondyle to the Gerdy tubercle, is used in the majority of these procedures.

The Gerdy tubercle is discovered to be the best attachment point for extra-articular reconstructions for anterolateral rotatory instability. When there is severe anterior instability due to injury or late stretching of the secondary stabilising capsular structures or the lateral side of the knee, this procedure is used primarily in conjunction with an intra-articular reconstruction.



  • Reduces the anterolateral rotatory subluxation but does not restore the ACL's normal anatomy and function.
  • Has a high rate of failure when used alone.


Intra-articular Procedure

Arthroscopy procedure advancements have resulted in better results in ACL injury rehabilitation. This procedure may involve a small arthrotomy incision that keeps the vastus medialis obliqus muscle connected to the patella. This procedure can be done using either an endoscopic or a double incision arthroscopic technique.

Various tissues/grafts, including extensor mechanism, patellar tendon, iliotibial tract, semitendinousus tendon, gracilis tendon, and menisc, have been used to anatomically reconstruct the torn ACL. All of these can be used in autografts, which are grafts taken from the patient undergoing surgery. Allografts and synthetic ligaments are two other options. The steps in this procedure are as follows:

  • Graft selection: The type of graft used is determined by the length of the surgery. Patellar bone grafts and hamstring tendon grafts are the most commonly used autografts (semitendinosus and gracilis)
  • Diagnostic arthroscopy is performed in conjunction with any meniscal debridement or repair that is required. Partial thickness tears, displaced bucket handle tears, and the status of the articular surfaces, including the patellofemoral joint, are all given special consideration.
  • Graft Reaping: To obtain the graft, a mini incision is made from the distal pole of the patella to 2.5cm below the tibial tubercle. After retracting the other structures, the graft to be harvested is sharply outlined and harvested with a micro oscillating saw blade. Typically, a triangle bone plug profile is obtained.


Pre-operative rehabilitation

ACL reconstruction Pre-operative rehabilitation

Pre-operative rehabilitation programs are also essential for maintaining muscle strength while awaiting reconstruction. A 20% pre-operative quadriceps strength deficit was found to be one of the most important predictors of poor clinical outcome, with a 15% decrease at two years post-operatively when a deficit was present.

Furthermore, lower quadriceps strength compared to the contralateral side was associated with a lower hop test score and a lower, but not statistically significant, International Knee Documentation Committee (IKDC) functional score. Indeed, a five-week rehabilitation exercise program in patients with ACL injury was shown to significantly improve their knee functional outcome.


Recovering from an ACL reconstruction

ACL reconstruction usually takes six months to a year to fully recover from. Within a few days of your operation, you'll see a physiotherapist, who will give you a rehabilitation program to follow, complete with exercises personalized. These will vary depending on a variety of factors, including the extent of your knee damage and the level of activity you hope to resume.

Following your rehabilitation program will assist you in regaining full strength and range of motion in your knee. Many people are able to walk without crutches within two weeks of having surgery. It usually takes six to nine months to be able to return to sports.

This varies from person to person and is determined by the sport you play and how well you recover. When they return to sports, some people wear a knee brace. However, they can be bulky and uncomfortable to wear. You don't have to wear one because it doesn't appear to affect how well your knee functions. However, because your knee will be supported, you may find that it boosts your confidence.

During your recovery, you can take over-the-counter pain relievers like paracetamol or anti-inflammatory drugs like ibuprofen. Make sure to read the patient information that comes with your medication, and if you have any questions, seek advice from your pharmacist. To help reduce pain and swelling, apply ice packs (or frozen peas wrapped in a towel) to your knee. However, do not apply ice directly to your skin as this can cause damage.

Your surgeon will be able to tell you when you will be able to return to work, driving, and other activities.


What to Expect?

ACL reconstruction Surgery Expectation

Arthroscopic surgery is frequently performed as an outpatient procedure, which means you will not spend the night in the hospital. Other surgeries may necessitate a couple of days in the hospital.

You will be exhausted for several days. Your knee will be swollen, and you may experience numbness around the incision. It's possible that your ankle and shin are bruised or swollen. To reduce swelling, apply ice to the affected area. The majority of this will go away in a few days, and you should notice an improvement in your knee soon.

Keep your incision clean and dry while it heals, and keep an eye out for signs of infection.

Physical rehabilitation following ACL surgery can take anywhere from a few months to a year. The time it takes to return to normal activities or sports varies from person to person. Most people take at least 6 months to return to normal activity after surgery.


Conservative versus surgical treatment

Conservative versus surgical treatment

Surgical management of an ACL tear is considered the "gold standard" of care in young adults who want to return to pre-injury activity. Non-operative management of ACL-deficient knees has previously been proposed as an alternative, but has been linked to poor functional outcome.

Non-operative treatment, in particular, resulted in poor and fair functional outcome scores that prevented the majority of patients from returning to pre-injury activities, as well as an increased incidence of secondary ACL and meniscus surgery. As a result of the better outcomes of ACL reconstruction, surgery is now the first-line treatment for ACL-deficient knees in active patients.

While conservative treatment of ACL-deficient knees has fallen out of favor due to poor outcomes in the last ten to fifteen years, a recent randomised controlled trial (RCT) suggested that some patients with certain characteristics can be effectively managed non-operatively. It was proposed that a structured rehabilitation program with optional ACL reconstruction at a later stage, if necessary, could produce similar results to early ACL reconstruction.

The morbidity and risk of late knee injuries appear to outweigh any potential benefits of a conservative approach, particularly in young active patients who want to resume pre-injury activity levels.

In ACL-deficient patients, the frequency of subsequent meniscal and chondral injuries is higher in skeletally immature patients. Early in skeletally immature patients, an association between medial meniscal tears and time to ACL reconstruction was discovered, implying that a delay in treatment may be etiologically responsible for these meniscal injuries.

Similar studies found an increased incidence of chondral injuries in association with medial meniscal tears, in addition to the above link.

According to prospectively collected MRI data, approximately 20% of skeletally immature ACL-deficient patients will sustain a new meniscal injury within the next four years. As a result, the decision to operate or not on an ACL injury in a child should take into account the high risk of ensuing knee injuries and their long-term consequences.


Complications of ACL reconstruction surgery

ACL reconstruction surgery complications

In general, ACL reconstruction surgery is risk-free. Complications that may occur as a result of surgery or during rehabilitation and recovery include the following.:

  • Problems related to the surgery itself:
  1. Numbness in the surgical scar area.
  2. Infection in the surgical incisions.
  3. Damage to structures, nerves, or blood vessels 
  4. Blood clots in the leg.


  • Graft tendon complications (loosening, stretching, re-injury, or scar tissue). The screws that hold the graft to the leg bones may cause complications and must be removed.
  • Range of motion is restricted, usually at the extremes. For example, you may be unable to fully straighten or bend one leg as far as the other. This is unusual, and in some cases, additional surgery or manipulation under anesthesia can be beneficial. Rehabilitation aims to restore a range of motion between 0 degrees (straight) and 130 degrees (curved) (bent or flexion). It's critical to be able to straighten your knee so you can walk normally.
  • Crepitus is a grating of the kneecap as it moves against the lower end of the thigh bone (femur), which can develop in people who did not have it prior to surgery. This can be painful and have an impact on your athletic performance. In rare cases, the kneecap may be fractured during surgery or as a result of a fall onto the knee soon after surgery.
  • When kneeling, there is pain at the site where the tendon graft was taken from the patellar tendon or on the lower leg bone (tibia) where a hamstring or patellar tendon graft is attached.
  • The graft was injured again (just like the original ligament). The second surgery is more difficult and less successful than the first.

Understanding the long-term effects of an ACL tear is critical. Following an ACL tear, the incidence of knee osteoarthritis (OA) rises to between 15% and 20%, a tenfold increase. It is estimated that more than half of patients who sustain an ACL injury will develop symptomatic OA within the next 10 to 20 years.

An ACL tear, when combined with a meniscectomy, can increase the likelihood of OA. In particular, in a ten-year follow-up cohort study, the presence of intact menisci was associated with normal radiographic findings in approximately 88 percent of patients versus only 63 percent when meniscectomy was performed. When compared to meniscal injury alone, ACL tears have been shown to cause radiographic changes at a younger age, indicating their importance.

Male gender, higher BMI, time from injury to reconstruction, previous meniscectomy, and the presence of cartilage degeneration in the medial compartment at surgery were all linked to the development of radiographic knee OA in the future. 


Alternatives to ACL reconstruction

If you injure your ACL, you will most likely receive physiotherapy first, even if surgery is required. Surgery isn't usually performed right away because your surgeon will give you some time to allow any swelling to subside.

The alternative to surgery is to continue with physiotherapy. You might discover that this is all you require. To protect your knee, your doctor may also recommend measures such as wearing a knee brace during weight-bearing exercise. You can also choose to postpone surgery and instead focus on physiotherapy. Those who require surgery later on perform just as well as those who are operated on within a few weeks of their injury.

Speak with your doctor for more information. They can advise you on the best treatment options for your specific situation and needs.



Anterior cruciate ligament reconstruction (ACL reconstruction)

The reconstruction of the anterior cruciate ligament (ACL) is one of the most common orthopaedic procedures performed worldwide.

An interprofessional team comprised of an emergency department physician, orthopedic surgeon, sports physician, nurse practitioner, and physical therapist is best suited for ACL diagnosis and management.

Anterior cruciate ligament tear is a devastating event for every patient, and proper management is essential not only to ensure return to pre-injury activity but also to prevent long-term complications from the knee injury. Despite the presence of several controversies in ACL reconstruction, systematic research was able to answer critical questions.

In patients who want to resume their pre-injury activity level, surgical management of ACL tears appears to be the answer. The timing of reconstruction and rehabilitation is critical for a successful outcome. Because each type of graft has distinct advantages and disadvantages, it is critical to carefully select the graft for each patient. Finally, the surgical technique should adhere to the fundamental principles of ACL biomechanics and anatomy to ensure proper graft positioning and a positive clinical outcome.

The "RICE" therapy, which includes rest, ice, compression of the affected knee, and elevation of the affected lower extremity, is used as an acute treatment. Patients should be non-weight bearing and, if necessary, may use crutches or a wheelchair. Over-the-counter medications such as NSAIDs can provide pain relief, but this is usually at the discretion of the treating physician.

Patient selection, surgical technique, postoperative rehabilitation, and associated secondary restraint ligamentous instability all play a role in successful anterior cruciate ligament reconstruction.

Graft failure can also be caused by mistakes in graft selection, tunnel placement, tensioning, or fixation methods. The comparison studies in the literature show that regardless of the graft used, the outcome is similar. The choice of graft is incidental to the operation's main goal of tunnel placement.