The Anterolateral Ligament (ALL): Addressing Knee Instability After ACL Surgery

A person adjusting a knee brace while sitting on a couch at home.

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If you have torn your ACL and gone through surgery, only to find your knee still feels unstable or gives way during movement, you are not alone. For some patients, a structure called the anterolateral ligament (ALL) may be part of the reason why. In Singapore, ALL reconstruction has become an increasingly discussed option for patients seeking a more comprehensive approach to knee stability.

Understanding the Anterolateral Ligament: Why It Matters for ACL Recovery

In many cases of persistent instability, the ACL was not the only structure injured. The anterolateral ligament, a small but important stabiliser on the outer side of the knee, may also have been damaged. Because awareness of the ALL has grown only in recent decades, it was not always assessed or addressed during earlier ACL reconstructions.

What Is the Anterolateral Ligament (ALL)?

The anterolateral ligament (ALL) is a distinct ligament located on the outer (lateral) side of the knee. It runs from the outer part of the femur (thigh bone) to the tibia (shin bone) and plays a role in controlling the rotational movement of the knee, particularly the inward twisting of the shin bone relative to the thigh.

Think of the ALL as a stabilising strap on the outer edge of your knee. When it is intact, it helps prevent the knee from rotating excessively during pivoting, cutting, or twisting movements.

Although the knee has been studied extensively for over a century, the ALL was only formally described and named in 2013. Before this, surgeons primarily directed attention to the ACL during reconstruction, without always accounting for the ALL’s contribution to rotational stability.

How the ALL Works Together with the ACL

The ACL and the ALL are two separate structures, but they work as a team to keep your knee stable during movement.

The ACL primarily controls forward-backward movement of the shin bone relative to the thigh. The ALL helps control rotational movement, specifically the inward pivot of the shin bone during twisting activities.

A useful way to think about this: imagine a backpack secured with two straps. One strap holds the pack from sliding forward, while the other prevents it from spinning sideways. If only one strap is attached, the pack remains partially unstable. The ACL and ALL work in a similar complementary way.

As understanding of knee biomechanics has deepened, surgeons have recognised that the rotational component, controlled in part by the ALL, was sometimes being left unaddressed.

The Pivot Shift Problem

A common clinical sign that the ALL may be involved in persistent knee instability is a phenomenon called “pivot shift.” This describes the sensation of the knee suddenly giving way, slipping, or catching during a turning or cutting movement.

Patients often describe the knee feeling unreliable during sport, or even during everyday activities like turning quickly. Some people notice a clunking or shifting sensation.

When ACL reconstruction alone does not fully resolve this pivot shift instability, it may suggest that the ALL was also injured and was not addressed during the original surgery.

Why Do Some ACL Reconstructions Fail?

ACL reconstruction has a recognised re-tear rate, particularly in younger and more physically active patients. Several factors can contribute to ACL re-injury or persistent instability after reconstruction:

Unaddressed ALL damage: If the ALL was also torn at the time of the original ACL injury and was not reconstructed, the knee may remain rotationally unstable even after a successful ACL repair.
Graft healing issues: The replacement graft used in ACL reconstruction takes time to integrate with the bone. During this period, the knee may be vulnerable, particularly if the patient returns to sport before the graft has fully matured.
Returning to sport too early: Resuming high-demand physical activity before the knee is genuinely ready is one of the more common contributors to re-injury.
Anatomical variations: Some patients have naturally steeper tibial slopes or looser connective tissue, which places greater stress on the ACL graft and may increase re-injury risk.
Missed or underestimated ALL injury: In some cases, ALL damage is present but not identified on initial imaging or examination, meaning it is not factored into the surgical plan.

Not every ACL failure is related to the ALL, but for patients with persistent rotational instability, it is worth investigating.

Who Is Most at Risk of ACL Re-Injury?

Certain groups face a higher risk of re-tearing their ACL or experiencing ongoing instability:

Young athletes: Particularly those under 25, whose activity levels and developing musculature place higher demands on the knee.
Patients returning to pivoting sports: Football, basketball, netball, rugby, and martial arts all involve rapid direction changes that stress the rotational stabilisers of the knee.
Patients with high-grade pivot shift instability: If examination reveals significant pivot shift before or after surgery, the ALL may be contributing to that instability.
Patients with previous ACL reconstruction: Revision ACL surgery carries a higher re-tear risk than primary reconstruction, making additional stabilisation worth considering.

What Is ALL Ligament Knee Surgery?

ALL ligament knee surgery, also referred to as ALL reconstruction or anterolateral extra-articular tenodesis (a technique that reinforces the outer knee using a tendon graft), is a procedure designed to restore rotational stability to the knee by reconstructing the anterolateral ligament.

In most cases, ALL reconstruction is performed at the same time as ACL reconstruction, not as a standalone procedure. The goal is to address both the forward-backward instability managed by the ACL and the rotational instability managed by the ALL, giving the knee a more complete restoration of its natural movement control.

You can explore elective orthopaedic reconstructive services to understand the range of knee surgery options available.

How ALL Reconstruction Is Performed

During ALL reconstruction, the surgeon typically uses a small tendon graft, often taken from the same leg, to recreate the anterolateral ligament. The graft is positioned along the outer side of the knee, running from the outer part of the femur to the tibia, mirroring the course of the natural ALL.

The graft is fixed at both ends using small anchors or screws. Because ALL reconstruction is typically performed alongside ACL reconstruction, the overall surgical time is longer than ACL reconstruction alone. However, both procedures are generally completed during a single operation.

Is ALL Reconstruction the Same as a Lateral Extra-Articular Tenodesis?

Patients researching this topic may come across the term “lateral extra-articular tenodesis” (LET) and wonder whether it refers to the same procedure. The two techniques are related but not identical.

Both ALL reconstruction and LET aim to add rotational stability to the outer side of the knee. However, they differ in their graft source, fixation points, and the specific anatomy they target. ALL reconstruction is designed to more precisely replicate the anatomy of the natural anterolateral ligament. LET is an older technique with a longer clinical history. Your surgeon will recommend the technique most appropriate for your specific anatomy and clinical findings.

Feature	ACL Reconstruction Alone	ACL Reconstruction with ALL Reinforcement
Approach	Intra-articular graft to replace the torn ACL	Intra-articular ACL graft plus an extra-articular graft on the outer knee
What It Addresses	Forward-backward knee instability	Forward-backward instability and rotational (pivot shift) instability
Typical Candidates	Most ACL tear patients with low-to-moderate instability	Patients with high-grade pivot shift, revision ACL cases, young athletes in pivoting sports
Key Considerations	Well-established procedure with strong long-term data	Additional surgical time; evidence base is growing; not appropriate for all patients

Who May Benefit from Combined ACL and ALL Surgery?

Not every patient who tears their ACL will need ALL reconstruction. For many people, ACL reconstruction alone achieves good stability and a full return to activity. Combined surgery is considered for a specific subset of patients where clinical findings suggest the ALL is contributing to instability.

Factors that may point towards combined ACL and ALL reconstruction include:

High-grade pivot shift instability on clinical examination before or after ACL reconstruction
Revision ACL surgery: Patients undergoing a second ACL reconstruction after a previous graft failure, where additional stabilisation may reduce re-tear risk
Young patients returning to high-demand pivoting sports: Where the combination of age, activity level, and sport type creates a higher-risk profile
MRI findings suggesting ALL damage: Specific patterns of injury visible on imaging that indicate the ALL was torn alongside the ACL
Persistent rotational instability despite a technically sound primary ACL reconstruction

The decision to proceed with combined surgery is always made on an individual basis, weighing the clinical evidence against each patient’s anatomy, activity goals, and overall health.

CTA Box: Not Every ACL Tear Needs ALL Reconstruction

ALL reconstruction is an additional tool available for selected patients, not a routine part of every ACL surgery. Many patients achieve good outcomes with ACL reconstruction alone. The appropriateness of combined surgery depends on your specific clinical findings, activity level, and surgical history. A thorough assessment with your orthopaedic surgeon is the right starting point.

What to Expect During Recovery from Combined ACL and ALL Knee Surgery

Recovery from combined ACL and ALL reconstruction follows a similar overall trajectory to ACL reconstruction alone, but the additional procedure on the outer knee may mean a slightly more conservative approach in the early weeks.

Physiotherapy is an important part of recovery and begins early. Your physiotherapist will guide you through a progressive programme designed to restore range of motion, rebuild strength, and retrain the neuromuscular control (the communication between your muscles and nervous system) that the knee relies on for stability.

Recovery timelines vary between individuals. Factors such as age, fitness level, the nature of the original injury, and how well the body responds to rehabilitation all influence the pace of recovery.

Key Milestones in the Rehabilitation Journey

Weeks 0 to 6: The focus is on managing swelling, protecting the grafts, and gently restoring range of motion. You will likely use crutches initially and gradually progress to walking without support. Gentle exercises to activate the quadriceps (front thigh muscles) and hamstrings begin early.
Weeks 6 to 12: As swelling reduces and range of motion improves, strengthening exercises become more progressive. Closed-chain exercises (movements where your foot stays in contact with the ground, such as gentle squats) are introduced. Balance and proprioception (your body’s sense of joint position) training begins.
Months 3 to 6: More dynamic exercises are introduced, including light jogging and sport-specific movement patterns. The grafts are still maturing during this phase, so high-impact and pivoting activities remain restricted.
Months 6 to 12: Return-to-sport testing and functional assessments guide the decision about when it is safe to resume competitive or recreational sport. Many patients return to full activity between nine and twelve months, though this varies considerably.

Making an Informed Decision About Your Knee Surgery

If you have experienced ACL re-injury, persistent pivot shift instability, or are planning a revision ACL procedure, it is worth asking your surgeon whether ALL reconstruction has been considered as part of your surgical plan.

The most appropriate approach depends on your individual anatomy, the nature of your injury, your activity goals, and your clinical examination findings. What matters most is that your surgical plan is based on a thorough assessment and a clear discussion of the options, risks, and expected outcomes.

When to Seek Professional Help

Your knee continues to feel unstable or gives way after ACL reconstruction
You notice a catching, slipping, or shifting sensation when turning or pivoting
Swelling recurs after physical activity, particularly after rotational movements
You are unsure whether it is safe to return to sport after a previous ACL injury
You are considering revision ACL surgery and want to understand all available options

Commonly Asked Questions

How Long Does Recovery Take After Combined ACL and ALL Reconstruction?

Most patients can expect a recovery period of nine to twelve months before returning to competitive or high-demand sport. The early phases focus on protecting the grafts and restoring movement, while the later phases involve progressive strengthening and sport-specific training. Individual recovery timelines vary based on age, fitness, and rehabilitation adherence.

Is ALL Reconstruction Available in Singapore?

Yes, ALL reconstruction is available in Singapore. It is typically offered by orthopaedic knee surgeons with experience in complex ligament reconstruction. The procedure is usually performed alongside ACL reconstruction for appropriately selected patients, rather than as a standalone surgery.

Does Adding ALL Reconstruction Make the Surgery More Risky?

Any surgical procedure carries inherent risks, including infection, bleeding, and anaesthetic considerations. Adding ALL reconstruction to an ACL procedure extends the operating time and involves an additional incision on the outer knee. Your surgeon will discuss the specific risks relevant to your case during your pre-operative consultation.

Can the ALL Be Repaired Without Surgery?

Minor ALL injuries may settle with conservative management, including physiotherapy and activity modification. However, in cases where the ALL has been significantly torn and is contributing to rotational instability, particularly alongside an ACL tear, surgical reconstruction is generally required to restore adequate stability.

How Do I Know If My ACL Failure Was Related to an ALL Injury?

Persistent pivot shift instability after ACL reconstruction, particularly the sensation of the knee giving way during twisting movements, can be a clinical indicator. MRI imaging may show evidence of ALL injury, and a thorough physical examination by an experienced knee surgeon can assess the degree of rotational instability. A combination of imaging and clinical assessment is typically used to guide this evaluation.

Next Steps

If you have been living with knee instability, have experienced an ACL re-tear, or are preparing for revision knee surgery, ask your knee specialist in Singapore to review any existing imaging for signs of ALL involvement and discuss whether your clinical profile suggests that combined reconstruction may offer a more stable long-term outcome.

Coming prepared with questions about pivot shift testing, graft options, and rehabilitation expectations will help you make a more confident, informed decision about your knee surgery.

Dr. Ambrose Yung

Specialist Orthopaedic Hip & Knee Surgeon

Dr Ambrose Yung Wai Yin is a Senior Orthopaedic Hip & Knee Surgeon with over 20 years of experience in the field of orthopaedics.

Areas of Expertise:

Knee Surgery: Complex procedures like revision knee arthroplasty, partial knee replacement, and primary total knee replacement.
Minimally Invasive Surgery: Shoulder, ankle, and knee surgeries with minimal scarring and quicker recovery times.
Limb Reconstruction: Specialized in both upper and lower limb reconstruction.

Computer-guided Knee Replacement: Dr. Yung trained at the prestigious Oxford University Hospital in the UK, where he specialized in computer-guided partial and total knee replacements.

Dr. Chee Kin Ghee

Specialist Hand & Orthopaedic Surgeon

Dr Chee Kin Ghee is a specialist hand surgeon with over 20 years of experience in hand and orthopaedic surgery.

His clinical expertise includes treatments for complex hand, wrist, and upper limbs injuries, wrist and finger joint replacement, minimally invasive hand and wrist surgery, and nerve compression release surgery

Dr Chee was awarded a 1-year fellowship (HMDP by MOH) & trained at world-renowned Wrightington Hospital Upper Limb Unit, UK.
He was trained in the management of complex upper limb conditions, including complex joint replacement of the shoulder, elbow, wrist, and hand, as well as modern minimally invasive upper limb surgery.

Dr. Low Mun Hon

Dr Low Mun Hon has over 20 years of experience managing trauma and orthopaedic clinical care. Prior to this, he has been in private practise as a practitioner at Singapore Sports & Orthopaedic Clinic (SSOC).

Dr. Low graduated from Monash University Medical School (Melbourne). Thereafter, he pursued his internship at The Alfred Hospital in Melbourne.

He subsequently continued his practice of medicine at Singapore General Hospital (SGH). During this period, he was awarded the membership of the Royal College of Physicians and Surgeons at Glasgow in 2008 & Master of Medicine in Orthopaedic Surgery (National University of Singapore) in the same year.
Dr Low had previously worked as an orthopaedic trainee at various local teaching hospitals i.e. Ng Teng Fong General Hospital (NTFGH), Tan Tock Seng Hospital (TTSH), KK Women’s and Children’s Hospital (KK Hospital) and Singapore General Hospital (SGH).

Justin Lim Xuan Li

Physiotherapist

Justin is a skilled and experienced physiotherapist who specializes in the treatment of neuro-musculoskeletal conditions (nerve, muscle and joint).

Over the years, he honed his clinical skills across all sectors of healthcare, allowing him to attain mastery of the sophisticated human body and address complex problems effectively, allowing him to successfully address complex neuro-musculoskeletal conditions at an accelerated pace.

Justin graduated from Trinity College Dublin and started his career in National Healthcare Group Polyclinics. His skills quickly gained recognition and was appointed as a clinical educator for physiotherapy students and even tasked to develop Clinical Practice Guidelines.
Subsequently, he continued his practice in community care settings such as Thye Hwa Kwan Rehabilitation Centres and Saint Andrew Community Hospital, where he focused on developing his skills for geriatric rehabilitation and improving quality of care in rehabilitation centres. He then moved on to private practice in Parkway East Hospital, specializing in post operative and outpatient rehabilitation.

Chan Jing Cheng (JC)

Physiotherapist

JC has over 12 years of experience in treating Chronic pain, Orthopaedic and Geriatric conditions.

He had worked at various Private Hospitals, Singapore General Hospital, NTUC Health Elder Care and Lions Home for the Elders.
He is passionate about solving complex musculoskeletal disorders and helping clients relief pain from trauma and illness.
He has a special interest in the Shoulder, Spine, Hip and Knee joint conditions.
He has helped thousands of clients go through rehabilitation smoothly and achieved higher satisfaction after orthopaedic surgery.

Zita Sham

Physiotherapist

Zita graduated with a Diploma in Physiotherapy from Nanyang Polytechnic (Singapore) in 2014 and started working in Ng Teng Fong General Hospital to serve her sponsorship bond.

Later in 2015, she pursued a Bachelor’s Degree in Physiotherapy from Trinity College Dublin, which was provided in Singapore Institute of Technology.

After completion of her studies, Zita worked in the Day Rehabilitation Centre in Jurong Community Hospital for 6 years, where she focused on community rehabilitation for a variety of patients. Patients that were mainly seen consisted of post-operative, geriatric and neurological conditions.
Zita also has a passion in musculoskeletal and sports physiotherapy and is looking to pursue that. She is also keen to provide home-based physiotherapy to reach out to those in need of her expertise.

Joanna Lim

Hand Occupational Therapy

Joanna’s primary specialization and passion is in hand therapy and upper limb rehabilitation, having more than 10 years of experience in this field.

Joanna obtained her Diploma in Occupational Therapy (Merit) from Nanyang Polytechnic in 2006. Under the MOH Health Science Scholarship, she graduated from La Trobe University, Australia, with a Bachelor’s degree in Occupational Therapy (1st class Honors) the following year. Upon graduation, she worked in Changi General Hospital and Sengkang General Hospital.

She has worked with hand and orthopedic surgeons in both inpatient and outpatient settings, providing quality therapy services for clients with a variety of hand and upper limb conditions, including fractures, sprains/strains, tendon injuries, nerve injuries, repetitive strain disorders and complex trauma injuries.
During her tenures at CGH and SKGH, Joanna was a Senior Occupational Therapist and held the role of Hand Therapy and Upper Limb Rehabilitation Unit Leader. She was in charge of clinical supervision and management of staff, manpower planning, and daily operations of the unit.