ACL injuries often occur suddenly and can be accompanied by a range of symptoms. Recognising these symptoms is crucial for prompt diagnosis and treatment. Common signs of an ACL injury include:

1. A “Pop” Sound: Many individuals report hearing or feeling a “pop” in the knee at the moment of injury. This sound is often a clear indication that the ACL has been torn.
2. Immediate Pain: A torn ACL typically causes significant pain almost immediately. The pain is usually intense and located in the center or back of the knee.
3. Swelling: Swelling of the knee usually begins within a few hours of the injury. This swelling is due to bleeding within the joint and can cause the knee to become stiff and difficult to move very quickly.

4. Instability: After an ACL injury, the knee may feel unstable or “give out,” especially during activities that involve turning. This instability is due to the loss of the ACL’s stabilising function.
5. Limited Range of Motion: The combination of pain, swelling, and instability often results in a decreased range of motion in the knee. Individuals will often find it difficult to fully straighten or bend the knee.
6. Difficulty Bearing Weight: Walking or putting weight on the injured leg can be painful and difficult, often leading to a limp or an inability to walk without assistance.

Diagnosing an ACL injury typically involves a combination of a physical examination and imaging to confirm the extent of the damage.

Physical Examination: A thorough physical examination by a physiotherapist is the first step in diagnosing an ACL injury. They will assess the knee’s stability, range of motion, and check for any signs of injury to other knee structures. Special tests like the Lachman test, anterior drawer test, and pivot shift test are used during this examination.

Magnetic Resonance Imaging (MRI): MRI is the gold standard for diagnosing ACL tears. It provides detailed images of both soft tissues and bone, allowing for a clear view of the ACL and any associated injuries, such as meniscal tears or damage to other ligaments. An MRI can also reveal partial tears or complete ruptures of the ACL.

X-rays: While X-rays do not show soft tissues like the ACL, they are often used to rule out fractures or other bone-related injuries that may have occurred simultaneously with the ACL injury. X-rays are particularly useful in cases of contact injuries where a fracture is suspected.

Arthroscopy: In some cases, particularly when the diagnosis is unclear or other knee injuries are suspected, arthroscopy may be used. This minimally invasive procedure involves inserting a small camera into the knee joint to directly visualize the ACL and other structures. Arthroscopy is also sometimes used to treat ACL injuries surgically.

Prompt and accurate diagnosis of an ACL injury is essential for determining the appropriate treatment plan. Whether surgical or non-surgical, early intervention can help prevent further damage and improve the chances of a full recovery.

Osteochondral lesions refer to areas where the cartilage that lines the ends of the bones in the knee (such as the femur or tibia) has been damaged along with the underlying subchondral bone. This can occur during an ACL injury, particularly when the knee experiences a high-impact force or twisting motion that not only tears the ligament but also crushes or shears off a piece of the bone and cartilage. These lesions can range from small, isolated areas of damage to larger, more complex injuries that affect significant portions of the joint surface.

Osteochondral lesions are a particularly serious problem because the knee’s articular cartilage does not heal as easily or as well as other tissues in the body. Cartilage lacks a direct blood supply, which limits its ability to regenerate. When an osteochondral lesion occurs, it can lead to persistent pain, swelling, and mechanical symptoms such as catching or locking of the knee. Over time, if left untreated, these lesions can result in joint degeneration, leading to early-onset osteoarthritis, a condition that can significantly impair mobility and quality of life.

Due to the complexity and potential severity of osteochondral lesions, they require prompt and expert attention. Diagnosis typically involves imaging studies such as MRI or CT scans, which can reveal the extent of the damage to both the cartilage and the underlying bone. Treatment may vary depending on the size and location of the lesion, as well as the patient’s activity level and overall knee stability. Options can range from conservative management, such as physical therapy and bracing, to surgical interventions.

Without appropriate treatment, osteochondral lesions can significantly impact long-term knee function. Even with successful ACL reconstruction, the presence of an untreated osteochondral lesion can lead to chronic knee pain, instability, and a decreased ability to participate in sports or other physical activities. The risk of developing post-traumatic osteoarthritis is also heightened, which can further complicate the recovery and rehabilitation process. Therefore, it is critical for anyone with an ACL injury to be thoroughly evaluated for the presence of osteochondral lesions and to receive specialised care from an orthopaedic expert experienced in managing complex knee injuries.

Recovering from an ACL injury can be a long and demanding journey, but with the right knowledge, treatment, and rehabilitation, many individuals can return to their pre-injury levels of activity. Rehabilitation is a vital component of this process, involving careful planning and execution of exercises, therapies, and lifestyle adjustments to ensure full recovery and minimise the risk of re-injury.

If you’re interested in diving deeper into the rehabilitation process, including detailed guidance on exercises, recovery timelines, and tips for a successful return to sports and daily activities, be sure to follow the next blog in this series. We’ll cover everything you need to know about navigating the road to recovery after an ACL injury.

The Sharp Physio Team