Everything you want to know about an anterior cruciate ligament injury.

Important facts and statistics about the anterior cruciate ligament injury

An awful lot of research has been done on anterior cruciate ligament injuries. As a result, we know an awful lot about all the ins and outs of this sports injury:

• 1 in 3000: Every year, 1 in 3,000 people will experience an anterior cruciate ligament rupture.
• 9 to 15 months: The rehabilitation period for an anterior cruciate ligament injury can range from 9 to 15 months. This depends on the severity of the injury and treatment.
• 4,000 cases per year: More than 4,000 cruciate ligament injuries are recorded each year in the Netherlands. This number is in the soccer world alone.
• 70% non-contact injuries: About 70% of VKB injuries occur without physical contact. This is also called a "non-contact" injury. This means that this injury usually occurs without an opponent or collision with an object. 
• 9,000 reconstructions per year: More than 9,000 anterior cruciate ligament reconstructions are performed annually in the Netherlands.

An anterior cruciate ligament surgery 

A severe anterior cruciate ligament injury may require surgery. Several surgical techniques are available, the most common method being reconstruction using a hamstring graft or a bone-patellar-tendon-bone (BPTB) graft. Both techniques give good results, with a low risk of complications and restoration of passive stability of the knee.

• Hamstring graft: This involves making the new cruciate ligament from tendons taken from the hamstring.
• BPTB graft: This method uses a piece of bone and tendon from the kneecap and tibia.

While both techniques are effective, it is important to note that the recovery process is individual and varies from patient to patient. No knee is the same and there is no universal treatment that works for everyone.

The Q angle and the risk of a knee injury

The Q corner (quadriceps angle) is a biomechanical measure used to assess the alignment of the knee. It is the angle formed between the line of the quadriceps muscle and the kneecap (patella), and it is measured in the frontal plane of the body. This angle provides insight into the forces acting on the knee, especially during movements such as walking, running and jumping.

In women, the Q-angle is greater on average than in men, and this can affect the likelihood of knee injuries, such as anterior cruciate ligament (ACL) injuries. The increase in Q angle in women is often attributed to a wider pelvic structure, which creates a greater angle between the upper leg (femur) and the knee.

A larger Q-angle can lead to increased lateral (outward) traction on the kneecap and increases the risk of knee problems, such as:

1. Patellofemoral pain syndrome (Kneecap problems due to wear and tear or poor tracking of the kneecap).
2. Increased risk of ligament injuries in the knee: A larger Q-angle may result in a less stable knee position during sports, especially during movements with rapid changes in direction or turning movements.

In women, the Q angle is often around the 15-18 degrees, while in men it is usually between the 10-15 degrees lies. This greater angle is one of the factors contributing to the greater risk of knee injuries in female athletes.

The consequences of an anterior cruciate ligament injury

The consequences of an anterior cruciate ligament injury can be significant, both physically and mentally. Athletes who have undergone VKB reconstruction have up to a 31% chance of re-injury, either to the same or the other knee. This can lead to long-term inactivity and also an increased risk of osteoarthritis, which can cause problems later in life.

• High cost: VKB reconstruction and the recovery process involve high costs. Medical costs for surgery average €2500, physical therapy costs €1000, and sick leave costs are estimated at €6500. This makes a total cost of €10,000 per injury.
• Osteoarthritis: The risk of developing osteoarthritis (joint wear) after a VKB injury is up to 10 times higher than in someone without knee problems.

Why brute force alone often leaves you wanting

Although an anterior cruciate ligament injury is often unexpected, there are ways to reduce the risk. Strength and being able to react quickly in unexpected situations are part of this.

The moment when an anterior cruciate ligament tears often has nothing to do with insufficient strength, but everything to do with the speed of reaction to external forces. This injury often occurs during situations where the body must react quickly to unexpected movements or external forces, such as a sudden change in direction, a wrong landing, or an abrupt stop while running.

When the anterior cruciate ligament tears completely, the stress on the knee is so sudden and intense that the muscles do not respond quickly enough to stabilize the knee. The body cannot adequately handle the sudden external forces due to a lack of coordination and responsiveness, and this leads to a vulnerable moment when the cruciate ligament tears.

This is exactly why coordinative training is so important in rehabilitation and not just strength training. You can still have such strong quadriceps or hamstrings, but if you are not trained to respond quickly and effectively to these external forces, you are still at great risk. The key to preventing another injury lies in improving the neuromuscular system so that muscles and brain can react and anticipate unpredictable movements faster.

Therefore, during rehabilitation, specific attention should be paid to training reaction skills, such as in balance exercises, plyometric training and sport-specific scenarios in which the knee is exposed to similar forces as it was during the injury. This helps to train the body to respond appropriately to external forces, significantly reducing the risk of re-injury.

Brute force alone is not enough. It is reaction time, coordination and the ability to absorb external forces that make the real difference in preventing another anterior cruciate ligament injury.

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