ACL Reconstruction Surgery

ACL reconstruction surgery is a procedure to replace a torn anterior cruciate ligament (ACL), one of the key ligaments that helps stabilise the knee joint. The ACL connects the thigh bone (femur) to the shin bone (tibia) and plays a vital role in maintaining knee strength and coordination, particularly during movements that involve pivoting, twisting, or sudden changes in direction.

This type of injury is common in athletes but can also occur during everyday activities such as falling, awkward landings, or sudden stops. When the ACL is torn, it often leads to pain, swelling, and a feeling of instability in the knee. While some people can manage with physiotherapy and lifestyle changes, surgery may be recommended for those who wish to return to an active lifestyle or experience ongoing symptoms.

This guide will explain everything you need to know about ACL reconstruction surgery, including:

• When surgery is needed and what symptoms it addresses
• How the procedure is performed and the types of grafts used
• What to expect during recovery and rehabilitation
• Potential risks and complications
• Answers to common patient questions about ACL reconstruction

Whether you’re considering surgery or supporting someone through recovery, this guide will help you understand what to expect and how to make informed decisions about treatment.

What is ACL Reconstruction Surgery?

ACL reconstruction is a surgical procedure used to replace a torn anterior cruciate ligament, one of the major ligaments that stabilise the knee. The ACL plays a key role in controlling forward movement and rotation of the shin bone in relation to the thigh bone. When this ligament is torn – commonly due to sports injuries, awkward landings, or sudden twisting movements – the knee can become unstable, making everyday activities and physical exercise difficult or even risky.

Rather than stitching the torn ligament back together, ACL reconstruction involves removing the damaged ligament and replacing it with a graft. This graft is usually a piece of tendon taken from another part of the patient’s body (called an autograft) or from a donor (allograft). Over time, the graft becomes integrated into the body and functions as a new ligament.

The procedure is typically performed using minimally invasive techniques with the aid of an arthroscope – a small camera inserted into the knee joint – allowing for precise work through small incisions. ACL reconstruction is not considered emergency surgery, but it may be recommended when instability persists, symptoms interfere with daily life, or the patient wants to return to sports and physical activity.

Why is ACL Reconstruction Surgery Performed?

ACL reconstruction is performed to restore stability and function to a knee with a torn anterior cruciate ligament. The ACL is one of four major ligaments in the knee and is essential for controlling rotation and forward movement of the lower leg. When it’s torn – most often during activities involving sudden stops, changes in direction, or impact – the knee may become unstable and prone to giving way.

Common causes of ACL injuries include:

• Sudden twisting movements during sports like football, rugby, or skiing
• Landing awkwardly from a jump
• Rapid deceleration or pivoting
• Direct trauma to the knee

Not all ACL injuries require surgery. Some people can manage with rehabilitation and activity modification, particularly if they’re not involved in high-impact sports or if the knee remains relatively stable. However, surgery may be recommended in the following situations:

• Ongoing instability or “giving way” of the knee during routine movements
• Desire to return to sport or high-level physical activity
• Combined injuries, such as damage to the meniscus or other ligaments
• ACL injuries in younger, physically active patients

Reconstructing the ligament helps restore stability, reduce the risk of further joint damage, and enable safe return to physical activity. It’s also performed to help prevent long-term complications like early-onset osteoarthritis that may develop from persistent joint instability.

How is the Procedure Performed?

ACL reconstruction is typically carried out as a minimally invasive (arthroscopic) procedure and usually takes around 60 to 90 minutes. It’s commonly performed as day surgery, meaning patients can go home the same day, though recovery continues over several months.

Preoperative Preparation

Before surgery, patients usually undergo:

• A clinical assessment and imaging (MRI or X-ray) to confirm the diagnosis.
• A period of prehabilitation, including exercises to reduce swelling, restore range of motion, and strengthen surrounding muscles.
• A review of medical history and discussion of graft options, surgical plan, and recovery expectations.

Anaesthesia

Most procedures are done under general anaesthesia, although some may involve regional nerve blocks for additional pain control.

Graft Selection

The torn ACL is replaced with a tendon graft, which serves as a scaffold for new ligament growth. There are two main graft types:

• Autograft – harvested from the patient’s own body (commonly the hamstring, patellar tendon, or quadriceps tendon).
• Allograft – donor tissue from a tissue bank. This may be used in revision surgeries or in patients where graft harvesting is less suitable.

Each option has its benefits and drawbacks, and the choice depends on factors such as activity level, anatomy, and surgeon recommendation.

Surgical Procedure

1. Small incisions are made around the knee.
2. An arthroscope (small camera) is inserted to provide visual access.
3. The remnants of the torn ACL are cleared.
4. Bone tunnels are drilled into the femur and tibia to secure the graft.
5. The graft is threaded through these tunnels and fixed in place with screws or other fixation devices.
6. The incisions are closed, and a dressing is applied.

After surgery, the graft begins a process of biological integration, eventually becoming a functional ligament over time.

Recovery & Rehabilitation

Recovering from ACL reconstruction surgery is a gradual process that can take 6 to 12 months, depending on individual healing rates, graft type, and personal goals – particularly if returning to sport. A well-structured rehabilitation programme is essential to restore strength, mobility, and knee stability.

Immediately After Surgery

• Patients usually return home the same day.
• The knee may be bandaged and supported with a brace or splint.
• Crutches are often needed for the first few days to weeks, depending on weight-bearing instructions.
• Pain, swelling, and stiffness are common early on but managed with medication, rest, and elevation of the leg.

The Role of Physiotherapy

A key part of recovery is supervised physiotherapy, which begins soon after surgery.

• Early stages focus on reducing swelling, regaining range of motion, and gentle muscle activation.
• Mid to late stages involve progressive strengthening, balance training, and functional movement retraining.
• Advanced stages may include sport-specific exercises, agility drills, and return-to-play assessments.

Typical Recovery Timeline

• Week 1–2: Walking with crutches, gentle movement exercises.
• Weeks 3–6: Improved range of motion, light strengthening.
• Weeks 6–12: Walking without aids, increased strength and control.
• Months 3–6: Low-impact activities, cycling, gym work.
• Months 6–9+: Return to running, pivoting sports, or competitive play (as advised).

Full recovery time varies, but return to contact or high-intensity sport is often allowed from 9–12 months post-op, once the knee is strong and stable.

Risks & Potential Complications

ACL reconstruction surgery has a high success rate, but like all surgical procedures, it carries some risks. Understanding these risks helps patients make informed decisions and know what to watch for during recovery.

Common Side Effects

• Swelling, bruising, and discomfort around the knee are common in the first few weeks.
• Stiffness or limited range of motion may occur but usually improves with physiotherapy.
• Scar tissue formation can occasionally limit mobility and may require additional treatment.

Possible Complications

• Infection at the surgical site, although rare, can occur and may need antibiotics or further surgery.
• Blood clots (deep vein thrombosis) – preventive measures include early movement and, in some cases, medication.
• Graft failure or re-tear – can happen if the knee is reinjured before full healing or due to poor graft incorporation.
• Nerve or blood vessel injury – uncommon but may cause numbness or weakness.
• Persistent instability or weakness – in rare cases, the knee may not regain full stability.

Long-Term Considerations

• Some patients may develop early osteoarthritis in the knee over time, especially if there was associated damage to cartilage or menisci.
• In revision cases (repeated surgeries), risks are slightly higher, and recovery may take longer.

Following your surgeon’s post-operative guidance and attending regular physiotherapy sessions are key to minimising complications and ensuring a successful recovery.

Frequently Asked Questions about ACL Reconstruction Surgery

How long does ACL reconstruction surgery take?

The procedure typically takes between 60 to 90 minutes, depending on the complexity of the injury and the type of graft used. It’s usually performed as a day case, so most patients go home the same day.

Is ACL reconstruction surgery painful?

The surgery itself is performed under anaesthetic, so there is no pain during the operation. After surgery, pain and swelling are common but can be effectively managed with medication, ice, and rest. Discomfort typically improves within the first couple of weeks.

What’s the difference between an autograft and an allograft?

• An autograft is tissue taken from your own body – commonly the hamstring, patellar, or quadriceps tendon.
• An allograft uses donor tissue from a tissue bank.

Autografts are more commonly used, especially in younger or active patients, while allografts may be suitable in revision surgery or when quicker recovery is desired.

Will I be able to return to sport?

Yes, many people return to sports after ACL reconstruction, particularly if they follow a structured rehabilitation programme. High-impact or pivoting sports (e.g. football, netball, skiing) often require 6 to 12 months of recovery before return to full play is advised.

Are there alternatives to ACL reconstruction surgery?

In some cases, especially for those with low activity demands or partial ACL tears, non-surgical treatment such as physiotherapy and activity modification may be appropriate. However, for patients with ongoing instability or goals to return to sport, surgery is often recommended for the best outcome.