Knee Popping After Injury? This Could be a Bad Sign...

POSTED ON IN Research BY Christopher Centeno

knee popping after injury

As you get older, some of us have joints that don't hurt but start to make noises. Remember those cute Rice Krispies guys, Snap, Crackle, and Pop? Although knee popping is a common condition, if your knees sound like a bowl of Rice Krispies or you're dealing with knee popping after injury, according to a new study, this may mean that arthritis is in your future.

But first, what causes knee popping and what’s knee arthritis?

Knee Popping Causes

What causes your knee to pop in the first place? If you don’t experience pain with your knee popping, then the noise is due to gas bubbles that pop in your knee. It’s also the natural sound your ligaments and tendons make when you stretch or extend them. Painless knee popping is not a symptom of a significant injury. However, it may be a sign of bad things to come.

However, if you experience pain with your knee popping, below are the most common causes:

  • Tear of the meniscus — This can happen over time or all of the sudden. The meniscus works to cushion the knee joint and when it’s loose, can cause a popping noise/sensation.
  • Tear of the ligament — This is the most common knee popping injury and the popping is usually heard and felt at the time of the injury.
  • Crepitus — Crepitus occurs when the joints or ligaments rub together while in motion. It’s less of a popping sound and more of a “crunching sensation.” Crepitus can occur with or without pain and is usually found in people with cartilage irritation or cartilage wear.
  • Hyperextension of the knee — When the ligaments in the knee extend past their normal range, it strains certain areas in the knee and people can feel popping as the knee heals.
  • Tendon Swelling — When the knee tendons swell, they can catch part of the knee as it’s in motion, causing a popping sound.
  • Runner’s Knee — Overuse of the knee can offset the joints and cause the knee to pop.

What is Knee Arthritis?

Knee arthritis occurs when one or more of your joints in your knee is inflamed. The main types of arthritis that affect the knee are posttraumatic arthritis, osteoarthritis, and rheumatoid arthritis – and it’s possible to have more than one type of arthritis at a time. Osteoarthritis is the most common and happens where the cartilage gradually wears away in your knee joint.  Posttraumatic arthritis occurs after a knee injury, such as a fracture or ligament injury. And rheumatoid arthritis is inflammation of the synovial membrane, which covers the knee joint.

Common symptoms of knee arthritis include:

  • Pain in the knee (gradual or all at once)
  • Swelling that occurs after sitting/resting
  • Knees that buckle or lock while in motion
  • Painful knee popping when walking
  • Poor range of motion in the knee
  • Sunken knee appearance
  • Increase of knee pain during seasonal changes

Study Finds Connection Between Knee Sounds and Arthritis

The purpose of the new study was to determine if there was a connection between those pops and creaks coming from the knees and arthritis. The large-scale, national study included 3,495 subjects who had crepitus (knee sounds, such as creaking, grating, or popping) but did not have knee arthritis at the start of the study. For the purpose of the study, the researchers defined arthritis as bone spurs on X-ray with frequent knee pain. Subjects at baseline could have one or the other but not both. The subjects were examined, had X-rays, and completed questionnaires at the start of the study and then every 12 months thereafter, up to 48 months.

The result? For most subjects, there was no significant change or worsening in the first year (which could be why so many continue to ignore their creaking and popping knees); however, over the four-year life of the study, around 18% of the subjects developed full-blown arthritis, with not just one indicator—frequent knee pain or bone spurs on X-ray—but both. The results were most prominent in the knee popping group who had X-ray evidence of bone spurs at the baseline but had no pain; this group was more likely to develop frequent pain later in the study and, therefore, knee arthritis. Another interesting finding was that the noisier your knees were, the greater the chance of knee arthritis.

So researchers concluded that there is a connection between crepitus, knee popping, and the later development of knee arthritis. Why would the two be connected? It likely all has to do with instability.

Knee Popping After Injury:Testing Knee Instability

We take for granted that our knees and other joints are held together by a complex array of ligaments and then further constrained by a symphony of muscle contractions. In fact, in normal knees, all of this works to sub-millimeter precision. However, for example, when a ligament is stretched, while it may hurt for a couple of days and then resolve, this can throw this system out of proper alignment and increase the forces in parts of the knee, including knee ligaments and tendons. Your only tell-tale sign might be cracking and knee popping after injury, until it's too late and the extra wear and tear causes arthritis.

Your knee might not necessarily feel unstable, but if your knees are making sounds, it's a good idea to check their stability. I have 4 easy knee-stability tests that focus on muscles and that you can actually perform on your own to help you determine if you have an instability issue. Failing just one of the tests means you have knee instability, and it's important that you follow up with a physician to determine the source of the problem. In addition, we often use stress ultrasound testing in the office to determine if the knee ligaments are lax and injured.

Another common source could be weak or irritated nerves in the back, which can also affect how the knee functions. Weak muscles can be strengthened, and irritated nerves can be treated, but you must pinpoint the problem and take the steps to address it. Just realize that sometimes, the cause of the instability is outside the knee.

Additionally, make an appointment to visit your doctor so they can properly assess your knee popping injury. By examining your medical history and your recent activity, they can make a proper diagnosis and individualized treatment plan. Be sure that when you meet with them to tell them all the important information regarding your knee injury — how it happened, when the popping started and other symptoms you have. That way they can determine the best treatment to keep your knee strong and healthy.

The upshot? If you have knees that sound like a bowl of Rice Krispies with our friends Snap, Crackle, and Pop making themselves known, don't ignore those sounds! In order to be that guy or gal who's still active at 80, you need to be taking care of small problems before they become big ones. Address the issues like knee popping after injury now before knee arthritis has a chance to fully set in!

  1. health tips
  2. knee
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