ACL Surgery & Reconstruction

Written by Dr Gowreeson Thevendran, MBChB (Bristol), MRCS.Ed, Dip. Sports Med.Ed, FRCS.Ed (Trauma & Ortho. ), FAMS (Singapore)

The anterior cruciate ligament (ACL) is one of the four major ligaments that provide balance when you walk, run or jump. It connects to both sides of the tibia (shin bone) and crosses over in front of the femur (thigh bone). The ACL’s primary role is to prevent excessive motion between these bones when a person bends their knee. Without an intact ACL, there would be little stability in your knee joint, which can lead to pain and injury.

In high-risk sports that require cutting, pivoting and jumping, the ACL plays a vital role in stabilising the knee joint and keeping it in place. Running diagonally in the middle of the knee, the ACL prevents the tibia from sliding and offers rotational stability for the knee so that movement remains optimal. However, this also makes it one of the more commonly injured ligaments of the knee. 

The most common injuries of the ACL are ACL sprain or ACL tear. ACL sprain is the stretching or tearing of some fibres in the ligament. On the other hand, an ACL tear is the complete rupture of the ligament. When an ACL tear happens, the lower leg bone may slide forward, and most would hear a “pop” in the knee. While a range of symptoms can follow after an ACL tear, a swollen knee is usually expected after the injury. Whether it’s a partial tear or a complete rupture in your anterior cruciate ligament, visiting an orthopaedic specialist is critical so you can get suitable treatment for your injury.

Causes of ACL Tears

While repetitive strain injuries are common for athletes, an ACL can be a serious problem for any individual, especially if it’s an ACL tear, as it can debilitate them for months. The common causes of an ACL injury include:

  • A result of a sudden stop
  • Direct impact against another player or 
  • Landing awkwardly after jumping high
  • Rapid changes in direction 

There are also different factors that could increase your chances of an ACL sprain or tear:

  • Participating in contact sports, such as football, soccer, and basketball
  • Recreation activities like skiing
  • Poor conditioning before intense exercise or sporting activities
  • Performing faulty movement patterns
  • Wearing footwear that don’t fit you properly
  • Using poorly maintained sports equipment

Once you tear your ACL, it can be hard for the ligament to heal on its own. Therefore, finding an orthopaedic specialist or sports injury doctor in Singapore is crucial to address the discomfort.

How the ACL Tears

When subjected to excessive force, the ACL can sustain damage, leading to a tear. The mechanism behind ACL tears often involves a combination of factors, including biomechanics and force distribution. A sudden and forceful change in movement can strain the ACL beyond its capacity. 

During activities that require dynamic movements, the ACL is exposed to unique challenges. These movements can cause the thigh bone (femur) and the shinbone (tibia) to move in different directions, placing undue stress on the ACL. The ligament is responsible for restraining excessive forward movement of the tibia in relation to the femur. Therefore, sudden shifts in weight bearing, coupled with twisting or pivoting motions, can lead to overstretching or tearing of the ACL.

Individual biomechanics also play a role in ACL injuries. Factors such as muscle strength imbalances, improper landing techniques, and inadequate core stability can increase the risk of ACL tears. Poor muscle control during movements can lead to a lack of knee joint stability, making the ACL more susceptible to injury when subjected to unexpected forces.

Symptoms of an ACL Tear

Following an ACL injury, you may experience the following symptoms:

  • Pain in the centre of your knee
  • Pain in the back of one's leg 
  • Swelling around the knee joint 
  • Instability when walking or changing direction quickly 
  • Difficulty squatting down without putting weight on their knees

If you suspect that either an ACL sprain or ACL tear has occurred, it is crucial to get immediate medical attention. That way, the full extent of your condition can be determined by an orthopaedic surgeon who is trained in addressing orthopaedic injuries.

Diagnosing ACL TearsACL Tear Grades

An orthopaedic specialist will offer a diagnosis of your ACL through history and physical examination. During the physical examination, the specialist will assess the amount of motion present and check if the ACL is torn. At the same time, they will examine the other structures within the knee since ACL tears are associated with damage to structures in the knee, like collateral ligaments and cartilage.

You will also undergo X-rays to see if there are any fractures. Some patients may even be required to get magnetic resonance imaging (MRI) should their history and examinations be inconclusive. Additionally, MRI examinations can help the orthopaedic specialist evaluate the state of the cartilage and meniscus tissue so that you can get the right treatment for your condition. 

Generally, your ACL injury will be categorised based on the extent of the injury:

  • Grade 1 - Among the various categories of ACL injuries, Grade 1 stands as the mildest. In this classification, the ACL sustains minor damage due to overstretching without reaching the point of tearing. The ligament retains a degree of structural integrity, allowing it to maintain a semblance of stability within the knee joint.
  • Grade 2 - These injuries mark a distinct step in ligament compromise. Here, the ACL experiences a partial tear, signalling that the ligament's fibres have been stretched beyond their limits, causing a noticeable loosening. Consequently, the ligament's ability to provide comprehensive stability to the knee joint is compromised.
  • Grade 3 - This ACL injury category is characterised by a complete tear of the ligament or its detachment from the bone it's anchored to. This classification represents the most common type of ACL injury and presents a significant challenge due to the loss of ligament integrity. 

What Happens if ACL Tears Are Left Untreated?

Leaving an ACL tear untreated may have significant consequences, impacting both short-term function and long-term joint health. While the body has a remarkable ability to adapt and compensate, a torn ACL may lead to chronic instability, discomfort, and an increased risk of further injuries. It is important to address an ACL tear promptly by visiting an orthopaedic specialist to avoid these potential complications.

Is it Okay to Walk on a Torn ACL?

Walking on a torn ACL is possible, but it's generally not recommended. A torn ACL impairs the knee's stability, making it susceptible to giving way during weight-bearing activities. Walking without adequate support, such as a brace or crutches, can exacerbate the damage and increase the risk of causing additional harm to the knee joint.

Can a First-Degree ACL Tear Heal Without Surgery?

A first-degree ACL tear, which involves mild stretching of the ligament without tearing, may have the potential to heal without surgery in some cases. However, the likelihood of complete healing without surgery is relatively low compared to more severe tears. Non-surgical treatment approaches, including rest, physical therapy, and bracing, may be prescribed to manage pain. It's important to note that even with non-surgical treatment, the risk of persistent instability remains, and ongoing monitoring is essential.

Can an ACL Tear Lead to the Development of Osteoarthritis in the Knee?

When you have an ACL injury, there’s a higher risk of osteoarthritis. Developing osteoarthritis may even be possible, regardless of getting surgery to reconstruct the ligament. Several factors could increase your risk of osteoarthritis, like the severity of your injury, other injuries in the knee, or the level of physical activity you perform after the treatment. Consult your ACL surgeon to develop a post-operation plan to help you manage your injury in the long run.

Treatments Available for ACL Tears

An ACL specialist will determine your treatment based on your symptoms, health examination results, sport and activity goals (if any), and growth that remains in your growth plates. 

RICE - Rest, Ice, Compression, and Elevations

Non-surgical treatment is appropriate for grade 1 ACL injuries, which are typically ACL sprains. Adequate rest allows the body to heal naturally while applying ice and compression helps manage inflammation and swelling. Elevating the affected leg may further aid in reducing swelling. This conservative approach is often effective in cases where the ACL has been mildly overstretched without tearing.

Physical Therapy

Most partial ACL tears, grade 2, can be treated with physical therapy. A comprehensive rehabilitation programme aims to strengthen the surrounding muscles, improve joint stability, and enhance range of motion. Through targeted exercises, functional movements, and proprioceptive training, you may regain knee stability without resorting to surgery.

ACL Surgery

Surgical intervention, on the other hand, involves ACL reconstruction to avoid long-term problems or wearing a brace that supports your knee joint. Surgery is generally recommended for ACL injuries with complete tears and unstable knees. The cornerstone of this intervention is ACL reconstruction surgery, a procedure designed to rebuild the torn ligament and restore stability to the knee joint. During the surgery, an ACL specialist meticulously replaces the damaged ligament with a graft. This graft can be sourced from various options, including the patient's own tissue (autograft) or from a tissue donor (allograft). The choice of graft depends on several factors, including the patient's age, activity level, and overall health. 

Research suggests that autografts have a lower chance of rejection and disease transmission compared to allografts. Autografts also ensure faster incorporation into the body. But unlike allografts, autografts are more likely to put the donor site at risk of other health complications. Therefore, it is wise to talk to your ACL surgeon to consider suitable options for you.

When Is an ACL Reconstruction Needed?

When a patient has a completely torn ACL and is experiencing functional instability, an ACL reconstruction surgery may be recommended, especially if it affects their ability to physically function. Generally, ACL reconstruction surgery should be scheduled for between three and six weeks after the injury occurs. That way, the inflammation in the area subsides. Surgeries that are performed too early have the potential to develop a profound scarring response called arthrofibrosis.

Getting ACL reconstruction is advisable if the unstable knee could lead to other possible joint problems. It is also recommended if you experience other injuries due to repetitive instability episodes. 

With surgical intervention, you may manage the symptoms of ACL tears and prevent additional complications. 

Preparing for an ACL Surgery

When going to the orthopaedic clinic for your ACL surgery, make sure that you are fully prepared for it. Here’s a list of things you need to consider before your operation:

  • Research about the procedure - Make sure to get as much information as you can about your ACL surgery. You can also ask your surgeon if you’re unsure about anything. 
  • Be transparent about other medical problems - Before your procedure, disclose to your ACL surgeon any other health conditions you may have and ensure they will be under control on the day of the surgery.
  • Avoid eating before the operation - Receiving anaesthetics with an empty stomach is safer. Therefore, you may be advised to fast before your operation. 
  • Arrange help and transport - It’s recommended that you have someone escort you to and from the hospital so that you can ensure your safety post-surgery.

ACL Surgery Procedure

A general anaesthetic is first administered before the surgery. This will put you to sleep throughout the entire procedure. From there, the ACL surgeon will use knee arthroscopy to remove the damaged ligament. This is done by making a few small incisions – usually two or three – around the knee. They will then replace the ligament with a graft tendon, usually obtained from another part of your knee. Once this is performed, steri-strips may be applied to cover the incisions. The surgery can take about two hours. After which, you may return home on the same day. 

For ACL reconstruction, it will usually require up to six months of recovery before you may resume any sports activities. During this time, do note that you will need to follow specific rehabilitation instructions from your ACL surgeon to help with the recovery.

Follow-Up Appointments After ACL Reconstruction

Following the ACL reconstruction surgery, cold compress may be applied to reduce swelling on the operated area. Alongside this, painkiller medication may be given to manage pain symptoms.

To support your mobility, the ACL surgeon may suggest wearing a knee brace and utilising crutches. Regular knee check-ups, either weekly or monthly, will be scheduled. These check-ins enable the orthopaedic specialist to monitor any ongoing pain, swelling, range of motion, and leg strength.

To work towards recovery, your orthopaedic surgeon and physical therapist may collaborate to design a customised rehabilitation plan tailored to your needs and goals. Consistent follow-up visits are essential, as they allow adjustments to the plan based on your recovery phase.

Your rehabilitation plan may feature a variety of exercises to aid your knee post-ACL reconstruction:

  • Range of Motion Exercises - To prevent joint stiffness, common exercises in this category include heel slide and passive knee extension. 
  • Quadriceps Strengthening - Recover strength lost post-surgery, enhance knee stability, and improve overall function.
  • Hamstring Strengthening - Equal strength in quadriceps and hamstrings can prevent imbalances leading to poor knee mechanics. Strengthened hamstrings lend additional support for bend-and-extend leg movements.
  • Gluteal Strengthening - Ensures proper alignment between the hip and knee. It also increases awareness of joint position, enhancing stability and reducing fall risks.
  • Balance and Proprioception Training - Focus on joint awareness and stability, leading to improved joint control and reduced injury risk.
  • Functional Exercises - These exercises mimic everyday movements, preparing you for a confident return to daily activities.

Recovery Period for ACL Tear

After your ACL surgery, the majority of your recovery period will be dedicated to the rehabilitation phase. In the initial weeks, your physical therapist may design a rehabilitation programme that encompasses gentle stretches and strengthening exercises. During this phase, you may have to use a knee brace or crutches.

From approximately the third week to several months, you should be able to walk naturally, eliminating the necessity for a knee brace and crutches. However, even though you might perceive this stage as a full recovery, the reconstructed ACL is still in the process of healing and remains susceptible to re-injury. As such, you must avoid excessive strain during exercises and exercise caution against making sudden, forceful movements with your knee.

Around the six to twelve-month mark, upon evaluations conducted by your physical therapist, you may gradually continue to engage in light jogging or cycling. If you are an athlete, you can gradually reintegrate into your sport. At this point, you will be focusing on reestablishing the advanced functionalities of your knee. However, you must be cautious when performing strenuous exercises or movements to prevent undue stress on your knee joint.

Risks and Complications of an ACL Surgery

ACL surgery, like any surgical procedure, carries certain risks and potential complications. It is important to have a thorough understanding of these risks before making an informed decision about undergoing surgery. While ACL surgeries help with knee stability and function, there are several possible risks and complications associated with the procedure. As such, you must have a thorough discussion with your orthopaedic surgeon about the potential risks and complications of ACL surgery. Your surgeon will provide personalised advice, take measures to minimise risks and guide you through the recovery process to achieve optimal outcomes.

Choose OrthofootMD for Your ACL Surgery

Finding an appropriate ACL specialist for your injury is critical in your recovery journey. As an orthopaedic specialist, OrthofootMD strives to help patients gain their physical functionality and independence with an evidence-based approach and individualised care. 

We understand that no two cases are the same. Therefore, our specialist takes the time to get to know your health history and understand your condition to provide the suitable treatment. 

We Accept Insurance Plans

OrthofootMD is on the panels of different health insurance plans. We also accept Medisave. To know if any of these health insurance partners can cover your ACL appointments or surgery, you can talk to the personnel at any of our clinics!.

About Dr Gowreeson

Dr Gowreeson Thevendran

MBChB (Bristol), MRCS.Ed, Dip. Sports Med.Ed, FRCS.Ed ( Trauma & Ortho. ), FAMS (Singapore)


  • Orthopaedics and Trauma Surgery

Languages Spoken

  • English, Malay, Tamil


Dr Gowreeson Thevendran is an orthopaedic surgeon that specialises in orthopaedics and trauma surgery. His particular skill set is minimally invasive surgical techniques to treat foot, ankle, knee, and hip/thigh conditions. He pursued fellowship training for sports surgery at Chelsea & Westminster Hospital, UK and complex trauma and deformity correction at Royal Liverpool University Hospital, UK. He also continues to serve the Orthopaedic Department at Tan Tock Seng Hospital as a visiting consultant.


  • Bachelor of Medicine and Surgery, University of Bristol, England
  • Fellow of the Royal College of Surgeons, Edinburgh
  • Diplomate Faculty of Sports and Exercise Medicine, Royal College of Surgeons Edinburgh
  • Fellow of the Academy of Medicine, Singapore
  • SICOT (Societe Internationale de Chirurgie Orthopedique et de Traumatologie) National Delegate for Singapore
  • Scientific Programme Chairman for SICOT, 2019 - 2021 and Education Academy Chair (2021-2024)
  • Foot & Ankle Council Member, APOA (Asia Pacific Orthopaedic Association)
  • Foot and Ankle Specialty Committee Member, Asia Pacific Orthopaedic Association (APOA)


  • SICOT PIONEER Founders Award 2020
  • 2015 European Foot & Ankle Society ‘Best Podium Presentation’ Award
  • 2013 Singapore Orthopaedic Association Junior Travelling Fellowship
  • 2012 NHG Critical Talent Special Recognition Award
  • 1998 Enid Lindt Prize in Clinical Surgery
  • 1995 Public Services Department Full Medical scholarship

Global Contribution and Innovations

Dr. Gowreeson's work extends beyond his local clinical practice. As the Chair of the Education Academy of SICOT, he plays a role in orthopaedic postgraduate education on an international scale. He was involved in introducing Magnezix bioreabsorbable screws in Singapore and participated in a multicenter trial regarding them. His scientific publications, positions in international faculty, and contributions to educational projects reflect his active engagement in the broader orthopaedic community.

Frequently Asked Questions about ACL Tear & Reconstruction Surgery

11. Is there a difference in recovery time between traditional ACL surgery and minimally invasive techniques?
No, there isn’t a substantial difference in recovery time between surgery and minimally invasive techniques. The overall recovery time can vary based on factors such as the individual's overall health, the specific surgical approach employed, the extent of the ACL tear, and the patient's adherence to post-operative instructions and rehabilitation protocols.
22. What sets Dr Gowreeson apart in the field of ACL surgery?
What sets Dr Gowreeson Thevendran apart is that he has worked with numerous patients in the field of orthopaedics and trauma surgery for years. Prior to establishing his private practice, he led the Orthopaedics Departments in hospitals like Tan Tock Seng Hospital and worked as an Associate Programme Director of the NHG Orthopaedic Residency Training Programme. He also has extensive knowledge of minimally invasive surgical techniques for knee injuries like ACL tears. Moreover, he has authored over 50 scientific articles in the field of orthopaedics. As such, when you get your treatment from OrthofootMD, you can rest assured that you are in capable hands.
33. Are there any research contributions by Dr Gowreeson in the field of ACL surgery?
Dr Gowreeson has contributed to the writing and research of a review on the approaches for ruptured ACL. The title of the concept review is “Approaching the ruptured anterior cruciate ligament,” which has been published in the National Library of Medicine and cited in different studies related to the ACL. This review talks about the role of healthcare professionals in ACL tears and what happens if the diagnosis is missed at first presentation.
44. Does Dr Gowreeson provide second opinions for complex ACL tear cases?
Yes, Dr Gowreeson’s knowledge and experience in the field of ACL injuries enable him to offer thorough assessments that can aid you in making informed choices about your treatment path. Should you have a complex ACL tear case, you may make an appointment with Dr Gowreeson at OrthofootMD for more information.
55. Is ACL reconstruction surgery always necessary for a complete tear?
While ACL reconstruction surgery is a common treatment for a complete ACL tear, it's not always the only option. If you live a less active lifestyle, have a minor ACL tear or are willing to undergo intensive rehabilitation, you may choose a non-surgical option. However, surgery may be proposed to prevent further joint damage, especially if you want to return to high-demand activities.
66. Can a second-degree ACL tear progress to a complete tear if not treated promptly?
Yes, a second-degree (partial) ACL tear may advance to a complete tear if not addressed promptly and appropriately. Partial tears compromise the integrity of the ACL, making it more vulnerable to further damage, especially during physical activities or movements that strain the ligament. Without timely intervention, the weakened ACL is at an increased risk of tearing completely, leading to instability and potential complications.
77. Can ACL tears occur in non-athletes or individuals with sedentary lifestyles?
Yes, ACL tears can occur in individuals who are not actively engaged in sports or have sedentary lifestyles. While sports-related activities are often associated with ACL injuries due to sudden pivoting or twisting motions, these injuries can also happen in everyday situations. Accidents, falls, missteps, and even wear and tear over time can lead to ACL tears in non-athletes or those with less active routines. The ligament's susceptibility to injury is not limited to athletic endeavours.
88. How can I manage pain and swelling in the knee following ACL surgery?

You can manage pain and swelling following an ACL surgery through different ways, including:

  • Pain Medications: Your doctor may prescribe pain medications to manage discomfort.
  • RICE: Rest, Ice, Compression, and Elevation can help reduce swelling and pain.
  • Physical Therapy: Performing prescribed exercises and following the physical therapist's recommendations can address pain.
  • Follow Medical Advice: Adhering to post-operative care instructions provided by your healthcare team is crucial to addressing ACL tears.

Always consult your healthcare provider for advice on pain management following ACL surgery!

Clinic Location


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