How Knee Injuries Can Lead to Osteoarthritis: A Simple Guide

Knee osteoarthritis (OA) is a condition that causes pain and stiffness in the knees. It can happen naturally as we age, but did you know that knee injuries can also lead to it? Let's break down a 6-year study that looked into how knee injuries can trigger or worsen knee OA.

The Study: What Did They Do?

The researchers followed 134 patients for six years after they had knee injuries. At the beginning of the study:

• Average age: 40 years old.
• Gender: 45% were women & 55% were men.
• Pain levels: The average knee pain severity was 4.8 out of 10.
• Knee function: The average score was 63.7 (out of 100) on the Lysholm Knee Function Score, which measures how well someone's knee works during daily activities.

These patients had their knees scanned initially, 1 and 6 years later using MRI (magnetic resonance imaging) to check for damage.

What Did They Find?

After six years, the researchers made some important discoveries:

How Many People Developed or Worsened Knee OA?

• 32% of the patients showed signs of new or worsening knee OA on their MRI.

This means that nearly 1 in 3 people experienced significant changes in their knee health after their injury.

When Does OA Start After an Injury?

The researchers noticed that most people who developed knee OA started showing signs within the first year after their injury. This means it's crucial to monitor knee health closely right after an injury.

Will osteoarthritis show up on X-ray?

In this study, X-rays and MRIs were used together to assess knee health over a 6-year period. The X-rays were used to evaluate the overall severity of osteoarthritis (OA) based on the K&L scoring system, which focuses on visible signs of joint condition like bone spurs and narrowing of the joint space. Meanwhile, the MRI provided a more detailed view of the knee''s internal structures, allowing the researchers to identify changes in the cartilage, meniscus, and bone.

The connection between the two imaging techniques is that most of the degenerative changes seen on the 6-year MRI (like cartilage defects, osteophytes, and meniscal issues) were found to be linked to the K&L score on the 6-year X-ray. This means that what was visible on the MRI often aligned with the findings on the X-ray, confirming the severity of OA over time.

Are You at Risk for Osteoarthritis?

Several things were related to the risk of developing or worsening knee OA:

• Age: Older patients were more likely to have knee OA.
• Gender: Women had a slightly higher risk.
• Knee Condition Before, During, and After an Injury:
  - Pre-Injury: A history of non-traumatic knee symptoms, such as knee pain or stiffness without a clear traumatic event, made individuals more likely to experience OA after an injury. This suggests that pre-existing knee issues could increase the knee's vulnerability to future damage.
  - Injury: Trauma during sports, especially from high-impact activities, often leads to more severe knee injuries and higher rates of OA progression. The physical demands of sports can cause intense damage to the knee joint.
  - Post-Injury: If the knee injury causes limitations in daily activities such as walking, climbing stairs, or bending, it may indicate more severe damage and a higher risk of developing OA in the future.
• Specific Knee Damage (as seen on MRI):
  - Cartilage defects: Damage to the cartilage that cushions the knee joint, making it more prone to wear and tear.
  - Bone spurs (osteophytes): These are growths that form on the edges of bones, often as a result of OA. Their presence can indicate ongoing joint damage.
  - Meniscal degeneration: Damage to the meniscus, which acts as a shock absorber in the knee, leading to greater joint stress and pain.
  - Bone Marrow Swelling (Oedema): This swelling, which can be seen in the bones of the knee, is a sign of inflammation and damage that often predicts future OA problems. If this swelling was present, it was a warning sign that the knee might experience worsening symptoms and damage over time.

What Can We Learn From This?

Here are the key takeaways from this study:

• Early Action Matters: If you hurt your knee, don't ignore it! Early check-ups can help detect issues like bone marrow swelling or cartilage damage.
• Some People Are at Higher Risk: Older age, being female, and having past knee problems increase the chances of developing OA after an injury.

This study gives us a clearer picture of how knee injuries can lead to arthritis. By staying informed and proactive, we can take better care of our knees and enjoy an active lifestyle.

Conflicting Findings

The study found some surprising results that we didn't expect:

• Body Weight (BMI): Even though the study didn't find a strong link between being overweight (high BMI) and knee OA getting worse, it's still important to think about how being overweight could make knee problems worse over time. When someone is overweight, it can cause changes in the body, like more inflammation, which might make knee OA worse. Even though this study didn't show a clear connection, having a high BMI could still be a risk factor for knee problems in the long run. The study might not have seen a strong link because it included a smaller group of people.
• Meniscus and Ligament Injuries: The study didn't find a strong connection between knee injuries like meniscus (the cushioning in the knee) or ligament damage and knee OA getting worse. But this might be because the study was done in regular doctor's offices (primary care), where people usually have less serious injuries. In places that specialize in treating knee problems (secondary care), people tend to have more serious injuries, and these injuries might be linked more strongly to knee OA.

What's Next?

If you've had a knee injury, talk to your GP or physiotherapist about how to protect your knee from OA. Regular exercise, maintaining a healthy weight, and following treatment plans can make a big difference. Remember, catching knee OA early can help keep your knees healthy and pain-free for years to come!

Reference

1. Marlous Kastelein, Pim A J Luijsterburg, Ingrid M Koster, Jan A N Verhaar, Bart W Koes, Dammis Vroegindeweij, Sita M A Bierma-Zeinstra, Edwin H G Oei - Knee osteoarthritis in traumatic knee symptoms in general practice: 6-year cohort study: BMJ Open Sport & Exercise Medicine 2016;2:e000153.
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