Knee Injury Overview

By Lars Blønd

This is an overview of some of the most common knee injuries and knee problems. However, there are other pages that deal with meniscus injuries, cruciate ligament injuries, loose kneecap, knee osteoarthritis and anterior knee pain.

Meniscus injuries and
cruciate ligament injuries

Meniscus injuries and ACL injuries are unfortunately often linked. Sometimes damage to the lateral collateral ligament injury also occurs. If you are unfortunate enough to have sustained both an ACL injury and a meniscus injury, read more here. My opinion is that if you need surgery for your meniscus injury, you might as well have an ACL reconstruction or ACL repair at the same time. This means you only need surgery once. If you need stitches for a meniscus injury, you should also have your knee stabilized. If this is not done, the risk of the meniscus injury reoccurring is too high.

Read more about ACL injuries
here

Read about meniscus injuries

here

There are a myriad of other knee injuries, of which anterior knee pain, jumper’s knee, runner’s knee, and goose foot are some of the most common, but information can be found elsewhere.

Lateral ligaments

Internal ligaments and external ligaments. The two ligaments provide lateral stability and can be partially or completely torn when the knee is twisted. The treatment of the two types of injuries is very different. The inside often heals on its own. The external ligament is more complicated and often needs to be reattached or reconstructed.

Healing of lateral ligaments

Your medial collateral ligament (MCL) injury is typically treated with a lateral stabilizing brace with a metal splint. There should be free movement in the knee and full support on the leg. Normally, dilated internal ligaments will have healed after 6 weeks. If you have an injury to the external ligament, it typically happens in conjunction with an ACL injury. Surgery is recommended as the ligament will not heal on its own.

Cartilage damage

Cartilage damage in the knee is common. Cartilage is a very important coating on top of the bones. The cartilage is very smooth and filled with water and helps the joints run smoothly. The cartilage layer also has a cushioning function. It’s hard to compare cartilage to anything else we know. In practice, the cartilage coating is similar to the peel of an orange. The cartilage can be knocked off by a strong twist or impact. The cartilage that is knocked off can remain in the knee and become a so-called mouse. The mouse sometimes floats around in the knee and can get stuck, causing the knee to lock. A hole is left where the cartilage has broken off. The cartilage damage can trigger pain under strain and often the knee will swell. Many cartilage injuries tend to resolve, while others continue to cause knee pain.

Osteoarthritis and cartilage damage

Arthrosis (osteoarthritis) of the knee is, in principle, also a form of cartilage damage, but this is more of a thinning of the cartilage. Over time, the cartilage can become poor quality and begin to break down. A fresh cartilage injury can develop into osteoarthritis over time. Read about knee osteoarthritis here

Treatment of various cartilage injuries

At one end of the spectrum, cartilage damage is found in very young people who have had a piece of fresh cartilage torn off. On the other end of the spectrum are older people with osteoarthritis, where cartilage begins to break down for unknown reasons. Between the two types of cartilage damage, there are all sorts of variations. Treatments for the two different types of cartilage damage are different. The treatment is somewhat complicated. Although there is a lot of research going on in the field of cartilage damage, major breakthroughs are still lacking.

What it takes for a cartilage injury to heal

A crucial factor in the healing of a cartilage injury is what’s called alignment. There is no good Danish word for this, but in English it is called alignement or correct tracking If you are bow-legged, calf-kneed or if your kneecap is crooked in its groove, this needs to be corrected before the cartilage damage is repaired. read more here. Some cartilage damage occurs as a result of these misalignments, similar to a car tire wearing crooked if there is an imbalance.

Treatment of cartilage damage with microfracture

In younger people (in this case, under 40 years old), cartilage damage has been treated for many years with something called microfracture or microdrilling. It is a type of treatment that uses an arthroscopic technique to clean up cartilage damage and make very small holes at the bottom of the injury, down into the bone itself. This causes a little bone marrow and blood to seep out of the holes. This then fills in the cartilage defect and over time this “filling” matures into tissue. Once this treatment has been completed, the knee should usually not be stressed for 8 weeks, as the filling needs time to mature to withstand the loads. It takes up to 1 year for the injury to heal 100%, and unfortunately, ⅓ of injuries do not heal. Read more about when not to undergo microfracture here

Cartilage smoothening during arthroscopic surgery

It’s rare that smoothing the cartilage with a surgical procedure can relieve knee pain. However, it can sometimes relieve knee locking for a period of time, especially if there is uneven cartilage behind the kneecap. In most cases, however, you don’t need to undergo knee arthroscopic surgery for knee osteoarthritis.

Cartilage transplantation

If the damage doesn’t heal, there are a myriad of other more complicated methods that are constantly being refined. Today, I prefer and have good experience with a method called “minced cartilage” or autocart. Here, some cartilage is taken from elsewhere in the joint and the cartilage is then cut into microscopic pieces and glued to the cartilage defect with biological glue made from your own blood.

Some cartilage injuries never heal due to misalignments in the knee, and in these people, the misalignments must be corrected at the same time with an “osteotomy” – see e.g.
tibia osteotomy
or
trochleoplasty
or
relocation of bone tendon attachment on the tibia
.

Hemicap – Knee button

If you are over 40, the chances of the cartilage healing are unfortunately small and in these situations a small metal implant called Hemicap can be used instead, which fills an isolated cartilage defect. This type of treatment is not suitable for osteoarthritis (wear and tear) injuries. Read more here

Enlarged mucosal fold – Plica Synovialis

Do you have an irritated plica ( synovial fold) in the knee, you should know that every knee has a larger or smaller plica in the knee. You basically have 4-5 synovial folds and they are all left over from fetal life and have no known functions. Here I will go through the 2 most important ones.

Internal and central synvial folds – infrapatellar plica

One synovial fold is located on the inside of your kneecap (mediopatellar plica). The second synovial fold is located at the front of the knee (infrapatellar plica) and is attached to the fat body of the knee.

Trauma to the knee

Sometimes a bump, twist or overload can cause one of your plica to become irritated and swell. The plica on the inside can get trapped between the kneecap and the inner femur bone. It typically causes pain and burning on the inside of the kneecap. If you get sore when your thumb runs over your plica and it slips under your finger, that’s probably what’s wrong. An irritated synovial fold can also cause pain and clicking in the front of the knee, as well as pain when sitting with the knee bent for long periods of time.

Treatment of synovial folds

The first step is to reduce the swelling of the synovial fold by keeping your knee still. You may also be able to take anti-inflammatory medication (NSAIDs or corticosteroids). Once your knee has settled down, a physiotherapist can work on your balance and movement patterns in your knee. If several months have passed, these treatments will often not be sufficient. You should then have undergone a surgical procedure to remove the plica. It is a procedure that you will typically recover from in a few weeks to a few months. It should be noted that your irritated synovial fold is not always visible on an MRI scan

Below picture of the inner plica

Link to study on the infrapatellar plica

Link to video about the infrapatellar plice

Osteoarthritis of the knee

As mentioned above in the section on cartilage damage, osteoarthritis is basically a cartilage damage where, for partly unknown reasons, the cartilage becomes poor quality and thins out. Osteoarthritis used to be called osteoarthritis, but this is a misnomer as we now know that it’s not always related to wear and tear. In advanced osteoarthritis, the cartilage is completely worn down and you “ride on the rim”, which means you ride bone against bone, with the femur bone riding directly against the tibia bone. Read more about here

Osteoarthritis and pain

Some people live reasonably well with osteoarthritis and only when it’s really bad do they start to experience symptoms. For others, the pain starts even before the cartilage is worn down. When cartilage starts to become diseased, the synovial membrane often becomes irritated, and since the synovial plica contains many nerves, pain is caused when the plica gets pinched. Some factors are known to contribute to the acceleration of osteoarthritis. Weight is a very important factor. You shouldn’t be deficient in vitamin D. Previous injuries such as cartilage, meniscus and cruciate ligament injuries are also important risk factors. Hereditary factors and knee misalignments such as being bowlegged or calf knee are an issue. Untrained muscles are also a risk factor. Please read more on the Danish Arthritis Society’s website. Paracetamol or equivalent is recommended for pain management.

GLA:D training

This is an exercise program that has been shown to help many people with osteoarthritis by delaying the need for knee replacement surgery.

Prevention of knee osteoarthritis

How to prevent the development of osteoarthritis. Firstly, you need to eat a healthy diet and keep your weight down, but you also need to avoid high impact impacts to the knee, such as running. Cycling, rollerblading, cross-training and cross-country skiing are forms of exercise that put healthy stress on the knee. Last but not least, the knee can be operated on straight if you are bow-legged, for example.

Tibial osteotomy – wedge surgery

Those who are bow-legged (Varus knee) or calf knee tend to get cartilage damage/arthrosis on the inside of the knee. For a cartilage injury or osteoarthritis on the inside of the knee, a Valgizing Tibial Osteotomy – HTO (IBalance) can be performed. relieve the pain. This straightens the knee and reduces the load on the inside, while placing more load on the outside of the knee. It has been shown that if you have incipient osteoarthritis on the inside, this type of surgery can rebuild all or part of the thinned cartilage. Osteotomy was once a common treatment. At some point, it was decided to insert a half knee prosthesis (Uniknæ) instead. The trend is now going the other way. This is because more gentle and less risky surgical techniques have been developed for tibial osteotomy (IBalance). Read more about tibia osteotomy here – Too few patients in Denmark are offered this treatment due to tradition and ignorance.

Free body in their knees

This is a small piece of cartilage that floats around the joint and occasionally gets stuck. A free body can usually be easily removed with a surgical procedure. It’s not always possible to see a free body on X-rays or MRI scans.

Baker’s cyst

Baker’s cyst is a fluid-filled outpouching at the rear of the knee. If you have a Baker’s cyst, it’s 90% certain that you also have a knee injury that caused the cyst. These are typically injuries to the meniscus, cartilage or cruciate ligaments. Usually the Baker cyst disappears when these injuries are treated. If you have a Baker’s cyst without these injuries, don’t have it operated on with an open technique, as about 60% will recur. The reason for this is that the Baker’s cyst is caused by a synovial fold at the rear of the knee that acts like a valve across the back of the knee. The synovial fold produces fluid that drains backwards between 2 muscles and Baker’s cyst is formed.

Open Baker cyst removal

If only the Baker’s cyst is removed from behind, the synovial fold is not removed. Instead, a special arthroscopic surgery is performed where the surgeon reaches all the way to the rear of the knee and removes the synovial fold and thus the valve through a special posterior access. Unfortunately, only a few orthopaedic surgeons are aware of this fact. Read more here. In children, it is usually sufficient to drain the cyst using an ultrasound scan and inject corticosteroid hormone at the same time, and this can also be attempted in adults before proceeding to surgery.

Here is a “leaflet” on topics – click here

Swollen knee

Knee swelling is a common condition for which there are many causes. It’s not normal for a knee to swell and it’s important to find out why. The most common causes are overuse, knee injury, meniscus injury, osteoarthritis (osteoarthritis), plica (enlarged synovial fold), but it can also just be a result of strep throat or a stomach bug.

Knee stiffness – Arthrofibrosis

Fibrosis is scar tissue and arthro means joint – so arthrofibrosis is too much scar tissue formation in joints, causing stiffness and often pain. Scar tissue is good – if it doesn’t form, we don’t heal. Sometimes the body creates too much scar tissue and this can be very unhealthy. How to treat it is quite complicated and I’m not an expert in the field. This may involve adrenal injections into the joint, as well as arthroscopic surgery and something called brissement, where the joint is moved through under anesthesia. You can read more here – https://www.kneeguru.co.uk/KNEEnotes/articles/general-articles/2019/all-about-arthrofibrosis-knee

There is also a Danish Facebook group about arthrofibrosis as well as a Twitter (X) group.

Noises and cracks from the knee

My knee is making noises and cracking and I’m afraid it’s wearing out. Just because your knee is making noises doesn’t mean it’s wearing out and many people will experience this at some point in their lives. As long as the knee doesn’t hurt or swell, it’s just noise.

Osgood Schlatter

Osgood Schlatter is a common overuse injury in young people in their teenage years. The pain is located at the front of the tibia attachment to the patellar tendon, just below the knee. If you’re unfortunate enough to have this, there’s probably not much you can do other than suck it up and exercise a little less. Once you’ve finished growing, the pain stops for most people. However, a few are unfortunate enough to have consequences in adulthood and experience pain from kneeling. If you suffer from it in adulthood, it’s very easy to treat with arthroscopic surgery – read more here.

Runners knee – Runners knee

This is typically an overuse injury where the bursa that lies between the outer femur bone (lateral femoral condyle) and the connective tissue of the outer thigh muscle (tractus ileotibialis) becomes irritated. The treatment is relief and stretching of the tendon via a physiotherapist or chiropractor. In rare cases, the tight tendon may need to be lengthened and the bursa removed.

Hoffa impingement, jumper’s knee, high kneecap

Here is a link to a Youtube video about the difference or similarity between Hoffa impingement, Jumpers knee and patella alta – click here click here.

Loose kneecap

Cruciate ligament injuries

You can read more here