An anterior cruciate ligament (ACL) sprain or tear is one of the most common injuries of the knee, particularly among sportsmen and women who compete in high-impact sports like football and basketball.
What causes ACL injuries?
This type of injury normally occurs as the result of a rapid change of direction, slowing down while running or coming to a sudden stop. Landing badly after jumping or a heavy collision can also cause ACL injuries. Women have a higher incidence of this type of ligament damage than men and if you have certain structural abnormalities, such as a difference in the alignment of the pelvis and leg or ligament looseness, you may be at increased risk.
Types of ACL injuries
There are different grades of ACL sprain according to the severity of the injury. A grade 1 sprain – the mildest form – is where the ligament has been slightly stretched but can still support the knee. A grade 2 sprain means there is a partial tear to the ligament and it has become loose. The most severe injury is a grade 3 sprain. This is where the ligament has been pulled away from the bone or torn in half, leaving the knee joint unsupported and unstable. Most ACL injuries are grade 2 or 3.
The severity of symptoms varies according to the grade of sprain. They include pain and swelling, instability of the knee joint and a loss of the full range of motion. There may be a popping sensation at the time of the injury and the knee might feel like it is about to give way. It is painful to walk with an ACL injury and for some people, surgery is needed to repair the damaged ligament.
Washington University study
A team of researchers at Washington University in St Louis, Missouri set out to establish whether having surgery to repair a torn cruciate ligament increases a person’s chances of needing a total knee replacement at a later date. The team was interested identifying whether there were any other risk factors that increased the chance of needing joint replacement surgery.
The study – published in The Bone and Joint Journal in 2024 – used the UK Biobank to identify 2,576 people who had previously undergone cruciate ligament surgery. Of these, 290 (11.25%) had subsequently had a total knee replacement. The majority (20.43%) had a joint replacement at age 80, while 9.10% were age 65 and 0.75% were aged 45.
An increased risk of knee replacement surgery
The findings showed that having previous surgery to repair an ACL injury significantly increased the likelihood of needing a total knee replacement at a relatively young age. Patients who’d had cruciate ligament surgery were 4.6 times more likely to undergo a total knee replacement by age 55 compared to those who hadn’t had this type of surgery.
Certain lifestyle factors, such as physically demanding work or obesity, increased the odds of total knee replacement surgery although no single-nucleotide polymorphism was associated with a greater risk of total knee replacement.
Preventing ACL injuries
Clearly, preventing ACL injuries is desirable for both short-term and long-term health. If you are competing in high-impact sports, it’s important to build up your fitness gradually and to have a good warm-up and cool-down regime. Building strength in your hips and thighs provides support for your knees and can help prevent ACL injuries. Good core strength helps to strengthen your muscles in the hips, abdomen, chest and back and improve your overall form. Good balance can help prevent injuries and we recommend practising jumping and landing safely. Professional coaching can ensure you are using good technique and you should always wear the right footwear.
For advice on diagnosing, treating and preventing all kinds of sporting injuries including ACL injuries, and for information about total knee replacement surgery, including Mako robotic arm assisted knee replacement, contact Professor Joseph Queally.
