The anterior cruciate ligament (ACL) stabilises the knee during movement and is commonly injured in sports such as football, basketball, or skiing. Injuries occur when the knee twists, overextends or sustains a direct impact. ACL tears, ranging from partial to complete, can impair mobility and daily function. This guide provides an overview of ACL injuries, including symptoms, treatment options, and prevention strategies.
Recognising the Symptoms of an ACL Injury
ACL injuries are usually accompanied by immediate and noticeable symptoms, signalling damage to the ligament:
Sudden Pain: A sharp, intense pain in the knee, typically making it difficult to bear weight or continue activity.
Popping Sensation: Many individuals feel or hear a distinct “pop” at the moment of injury, indicating possible ligament damage.
Swelling: Swelling develops rapidly within a few hours due to bleeding inside the joint, leading to stiffness and discomfort.
Instability: The knee may feel unstable, giving way or buckling when pressure is applied, especially during walking or standing.
Limited Range of Motion: Pain and swelling can restrict normal movement, making it difficult to fully straighten or bend the knee.
Contributing Factors to ACL Injuries
ACL injuries are often caused by sudden, forceful movements that place excessive stress on the knee joint. Common risk factors include:
Sudden Movements: Quick twists, pivots, or awkward landings can stress the ACL. Strengthening muscles and practising proper movement techniques can help reduce this strain.
Participation in High-Risk Sports: Sports such as football, soccer, and basketball involve rapid direction changes, jumping, and cutting motions, which increase the chance of ACL injuries.
Improper Technique: Poor muscle strength or improper movement patterns, such as the knee collapsing inward during landing, add strain to the ACL.
Previous Injuries: A prior ACL tear increases the risk of reinjury, especially if knee strength, balance, and function are not fully regained through rehabilitation.
Grades of ACL Injuries
ACL injuries are classified into three grades based on the severity of the ligament damage:
Grade 1: Mild Sprain
The ligament is stretched but remains intact, with no tearing. The knee joint stays structurally stable, with only mild swelling and discomfort.
Grade 2: Partial Tear
A partial tear compromises the ligament’s strength, reducing the knee’s structural stability. Swelling and pain are present, and the knee may feel slightly unstable, particularly during sudden movements.
Grade 3: Complete Tear
The ligament is fully torn, leading to a complete loss of structural support. The knee becomes unstable, making it difficult to bear weight or perform normal movements without the joint giving way.
Treatment Options for ACL Injuries
Treatment for ACL injuries depends on the severity of the tear and the patient’s level of physical activity. The goal is to restore knee stability and function, either through conservative management or surgery.
Non-Surgical Treatments
Physical Therapy
Physical therapy focuses on strengthening the muscles around the knee, including the quadriceps and hamstrings, to provide stability. It also improves joint flexibility, range of motion, and balance. Physical therapy alone may be sufficient for partial tears, allowing patients to regain knee function without surgery.
Bracing
Knee braces offer additional support by limiting excessive movement and stabilising the joint during physical activities. They are commonly used during recovery to prevent further injury and are often combined with physical therapy.
Medication
Nonsteroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen or naproxen, are used to manage pain and reduce swelling. These medications help make the rehabilitation process more comfortable.
Surgical Treatments
Surgical treatment is typically required for complete ACL tears or cases where the knee remains unstable despite non-surgical interventions.
ACL Reconstruction
This procedure involves replacing the torn ligament with a tendon graft, which can come from the patient’s own tissue or a donor. The new graft functions as a replacement for the damaged ligament, gradually integrating into the knee over time.
Knee Arthroscopy
This is a minimally invasive procedure that allows the surgeon to examine and treat injuries inside the joint using a small camera and surgical instruments. It is often used during ACL reconstruction to confirm the extent of damage and address any other knee injuries, such as meniscus tears. Arthroscopy reduces recovery time and surgical complications compared to traditional open surgery.
Preventing ACL Injuries
Preventing ACL injuries involves strengthening the quadriceps, hamstrings, and surrounding muscles to support the knee. Practising proper techniques for jumping, landing, and pivoting helps minimise strain on the ligament. Regular warm-ups and stretching enhance flexibility, further reducing injury risk. In some cases, a knee brace may provide additional stability during high-impact activities or after a previous injury.
Conclusion
ACL injuries can impact daily activities and physical function, but early diagnosis and a structured recovery plan can improve outcomes. For minor injuries, physical therapy may be sufficient, while more severe tears often require surgery. Strengthening knee muscles and using proper movement techniques are key to preventing future injuries. Prompt treatment and dedicated rehabilitation are necessary for maintaining long-term knee health.
If you are experiencing knee pain or instability, schedule a consultation today for an accurate diagnosis and a personalised treatment plan.
Dr. Kau Chung Yuan
MBBS (S’pore)
MRCS (Ireland)
MMed (Ortho)
FRCSEd (Ortho)
Dr Kau (许医生) is a Fellowship trained Orthopaedic Surgeon with a subspecialty interest in Hip and Knee surgery and has been in practice for more than 15 years.
He is experienced in trauma and fracture management, sports injuries, and joint replacement surgery.
Fellow of the Royal College of Surgeons Edinburgh, Orthopaedics (FRCS, Edin) 2014
Master of Medicine (Orthopaedics), Singapore (MMed) 2013
Member of the Royal College of Surgeons Ireland (MRCS, Ire) 2009
Bachelor of Medicine and Surgery (MBBS, Singapore) 2004
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