Lars Blønd, Author at Lars Blønd

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MRI Scan of the Knee

By Lars Blønd

MRI scan of the knee - this can be a very good idea

MRI scan of the knee

In case you a having a knee problem, in most situations it will be helpful for you to have an MRI scan of the knee - to make a diagnosis or to support the diagnosis or to exclude other reasons for your problem. MRI scans are really good for seeing meniscus tears, anterior cruciate ligament (ACL) tears and other ligament tears. The price has also declined in the past years and today it is close to 400 euro in Denmark. If your main problem is knee pain, I believe you should in most circumstances have an MRI scan of the knee and you should not have an arthroscopy without the MRI.

What is an MRI scan of the knee?

MRI scan is a magnetic resonance scan and by having a different magnetic field gradients it can generate images of the knee. Both open and closed MRI scanners exist and as far as I know, the quality from the closed ones is always better. You are supposed to lie supine, and claustrophobia is seldom a problem since your head is out site the machine.

How precise is an MRI scan of the knee?

In most situations it is very precise, however there is a number of exceptions. I will try to explain some of those here and what you need to be aware of. First of all an MRI of the knee not a answer book. A good clinical examination, in combination with your history about how the problem started and what type of pain or problem you might have, can been even more precise. Some things cannot be found by either a clinical examination or by an MRI scan and you may need to undergo an arthroscopy of your knee.

One of the problems with MRI scans is that the result relies on who is looking at the pictures. Normally the radiologist very good, but they may overlook things and some things might be so special that they even do not even know about it. Sometimes the radiologist has not received the appropriate information from the orthopaedic surgeon that is actually needed to look for a specific problem. The radiologist sends his report to the orthopaedic surgeon. Some orthopaedic surgeosn only look at this report and do actually look at the MRI scan pictures themselves. If they do, they may not know precisely what to look for if it is something rare. The main reason why I write this is not to scare you, but to make you aware that if you are in a situation with continuous pain and you have been told that the MRI is absolutely normal, you might need a second opinion.

What is typically overlooked by an MRI scan of the knee?

Anterior knee pain

I believe that one of the most common reasons to have anterior knee pain, and where also the findings seems to be normal, might be a synovial plica, since this structure can be difficult to evaluate on an MRI. Also trochlear dysplasia is often overlooked as well as patella alta. So the reason for this might be that the radiologist and/or the orthopaedic surgeon do not know how to precisely measure this. At least in Denmark some departments have cancelled the axial view, in order to save time and money. Nevertheless the axial view is the most important view in respect to kneecap instability and anterior knee pain, since this is where the trochlear dysplasia is noticed and the lateral trochlea inclination angle, the trochlear asymmetry and the TT-TG or TT-PCL is measured. So if those measurements are not mentioned and you are dealing with kneecap problems, ask the orthopaedic surgeon about those and if he does not know how to measure, perhaps you should ask for another orthopaedic opinion.

Meniscus tears

If a meniscus tear is suspected you can be 90% or more sure that the MRI will reveal this tear. However in some situations you can be unlucky that the tear is localised just between two MRI slices and therefore not visible. You might also have what is called a meniscus ramp lesion, that means that the meniscus is torn from the capsule in the rear part of the knee and is frequently associated with anterior cruciate ligament (ACL) injuries. The meniscus ramp lesions can be difficult to see both on MRI and during arthroscopy and are often overlooked. Also meniscus root tears might be overlooked on the MRI scan and "just" called a radial meniscus tear; however this type of tear can be very detrimental to the knee and in most cases surgery is indicated and that means the tear needs to be fixed or cut away.

Meniscus ramp lesion

In the figure on the left you see the knee from the side and there is a meniscus ramp lesion; however it is rather seldom the lesion is so clearly seen. Often such a lesion can be overlooked based on a little scar that covers the lesion, and this does also apply during the arthroscopy, and therefore careful exploration might be necessary.

Meniscus root tear before and after fixation.

Meniscus root tear and seen on MRI and you also see how the meniscus extrude (glide away over the edge of the tibia)

Anterior cruciate ligament tear - ACL tear

In most situations an ACL tear is seen very precisely on MRI; however there are exceptions. In some cases the ligament is not torn, but just overstretched and has becoming too long. This can be difficult to see on an MRI, but a clinical examination will in most situations reveal this. If you already have had an ACL reconstruction and your knee has become loose again, this can be difficult to see on an MRI, since the ACL graft will in most situations not become torn, but just slowly gets longer and longer.

Cartilage lesions

MRI scan can be very clear on large cartilage lesions, however smaller lesions can be difficult to detect and in those situations is the arthroscopy much more precise.

Just a little about MRI scans of the knee and what you should be aware of

Normal axial view of a left knee

Lateral trochlear inclination angle

Here you see a lateral trochlear inclination angle at 7 degrees, which is a little below 11 degrees that is the threshold for calling it trochlear dysplasia. The normal angle is 21 degrees. It is important that the measurement of the inclination angle is done at the most proximal axial view, where both of the posterior femur condyles are seen. The lateral trochlear inclination angle varies substantially from the top of the groove (caudal) to the bottom (distal).

Patella Alta - high riding kneecap

The patellotrochlear index is a more clinically relevant measurement of patellar height than other types of measurements. It is a measurement that says how big is the overlap between the trochlear groove and the kneecap. This is the only correct way to measure the height of the kneecap, and old measurements like the Insall-Salvati and Caton-Dechamp indexes are obsolete and imprecise. Those measurements do not say anything about the articulation between the patella and trochlea, and that is what patella alta is all about.

Patella Alta & Hoffa's fat pad Impingement

Above you see a figure that demonstrates a high-riding knee cap (patella alta). You also see an arrow that points to a white area. This is what is called Fat Pad Impingement. The white area is increased water content in the fat pad and this means inflammation. The inflammation is caused by the late engagement of the patella in the trochlear groove. This is due to a high riding Patella. The patella will first engage into the trochlea area when the knee is flexed several degrees. Since the pressure is not on the patella, it causes too much load on the fat pad. The increased load causes the inflammation in the Fat Pad. The solution is to bring down the kneecap. This is done with a distalisation of the tibial tubercle.

Meniscus Tears

By Lars Blønd

Meniscal tears may occur on their own or together with other injuries.

Meniscal tears

In every knee there is an inner and an outer meniscus. They job is to resorb the forces between the femoral and tibial condyles as they act as shock absorbers and distribute the pressures. The meniscus can get injured and there are several types of tears depending on the type of injury. The typical mechanism of trauma is is a twist of the knee, but the injury can a occur spontaneous during running or by squatting.

In some cases of a meniscal tear an arthroscopy is needed. Typically you either cut out the damaged part of the menisci or in other situations it is possible to repair the tear by using different kinds of meniscal sutures or anchors,In most cases the meniscal tear can seen on an MRI scan, while and ultrasound scan is unreliable.Sometimes the injury is so obvious, that you go directly to an arthroscopy.

The symptoms for meniscal tears are commonly pain in the knee aggravated when the knee is loaded and especially by doing turns. This can feel like something is catching or like sharp pain. Please see below if some of the seven classic symptoms are some of those that you experience.

pain in the joint line
stiffness and reduced range of motion
swelling
a feeling that the knee is untrustworthy

intermittent clicking, catching or popping
intermittent giving way
intermittent locking

Not all meniscal tears need surgery and especially in middle aged persons the symptoms can resolve, eventually helped by steroid injections and physiotherapist guide rehabilitation.Meniscal transplantations is an option in special selected cases, either by artificial menisci or by allograft menisci (menisci from (harvest from a cadaver).

Meniscal Root Tear

If you have a meniscal root tear you need surgery. This is based upon that the meniscus loose the ability to work as a shock absorber, when there is an avulsion of the meniscal root. Then the wear of cartilage will increase and this causes pain and early osteoarthritis. Unfortunately is this type of tear often overlooked by surgeons, since they are not aware that type of injuries exist. The problem is also that many radiologist, who are the ones who where supposed to see the injuries by MRI scans, also overlook those injuries. Read more here.

What if meniscal root tears are not operated? Read here

Meniscal tears and cruciate ligament tears

Meniscal tears and cruciate ligament tears often are associated, and sometimes there is also and injury to the site stabilising ligaments. My opinion is that in those situations, where you do surgery for a meniscal tear, you might as well do an concomitantly ACL reconstruction. Then you are only needed to have surgery once. If a meniscal tear is sutured, you must also stabilize the knee with an ACL reconstruction, otherwise will the meniscal repair retear.

“Unhappy triad” - That means tear of the ACL, the medial collateral ligament and the lateral outer meniscus.

There exist many types of knee injuries and here is anterior knee pain, jumpers knee, runners knee and pes anserinus pain, some of the most common, and those could be caused by overuse.

Meniscal root tear repair

Tibial Osteotomy

By Lars Blønd

Tibial osteotomy is an operation where the load through the knee is moved away from the inner aspect and towards the outer aspect. The operation used to protect the articular cartilage in cases of osteoarthritis.

Tibial osteotomy

Tibial osteotomy is also called a bone wedge operation, since you either do have taken out or inserted a bone wedge in the shin. The tibial osteotomy can be useful if you have osteoarthritis, which means damaged cartilage on the inner or outer site of the knee. If you are bow legged you will have increased load on the inner site of the knee (varus knee) and just upper site if you are knock legged (valgus knee). By a tibial osteotomy the angle in the knee is corrected and the leg is realigned. This means that the high forces on the damaged part of the knee is moved towards the other site of the knee where the cartilage is good. By unload the damaged cartilage the pain can slowly resolve and the damaged cartilage can regenerate over time. If you are a tibial osteotomy the time for a total knee prosthesis can be exposed a number of years. Precisely how long is difficult to say, since it depends on the severity at the time of the surgery, but from 5 - 20 years is realistic. The earlier the longer. Before the surgery you have to undergo a special x-ray examination to see calculate the precise angle of correction needed. The information further down is in respect to when you are bow legged, since this is must more common.

An alternative to surgery is that you use an unloader brace. You then use the brace when you are loading your knee while walking or running. The princip is a spring built into the brace and this absorbs the load on the inner site of the knee. See video here

Se video her

The operation

By the surgery the shin is opened on the inner site, and by using a special guide system the bone is cut 3/4 though and a plastic wedge is inserted that precisely corrects the preoperatively planned correction. By this the leg will get about a ½ cm longer. The plastic wedge is secured by four plastic screws. The plastic material very much mimic the bone and can be left and normally it should not be removed. The IBalance method is now 10 year old and is very secure and precise and has many advantages in comparison of using a metal plate. Sometimes a corresponding arthroscopy of the knee will be done.

After the operation

You will arrive to the recovery room and I will inform you about the surgery and you will receive the surgical report before you leave.

Pain

During the surgery local anesthetic will be applicated around the knee and this last for some hours. Sometimes the anesthesiologist doctor will supplement by a nerve block. It is normal that you will have some pain for the first weeks and you can reduces this by placing some ice wrapped in a towel on the knee. This can be applicated for 20 minutes every hour.

After the discharge

You will be mounted with a brace where you will be able to bend your knee. This brace is going to be used for 8 weeks and is going to protect you leg to brake until the bone has healed sufficiently. After 2 weeks the brace can be opened safely when you sit in a sofa. After 4 weeks you can omitted the brace while sleeping and in the bath. The first 2 weeks you are only allowed to load your leg with 5 kg and after the 2 weeks you are allowed to load by 20-40 kg (if you are in doubt how much this is then take a bathroom scales). After 4 weeks you are allowed full weight bearing. You have to expect that the lower leg including the foot will get swollen the first weeks after the operation. It is also common to get some bruises and some stinging (can be reduced by NSAID ointment). To prevent deep venous thrombosis you have to take a preventing pill once a day for 10 days. It is common that you need to take some strong painkiller after the surgery such as morphine and morphine often cause constipation. Therefore it is a good idea to prevent constipation by taking some laxatives. The site effect for this can be epistaxis and bruises and if this occurs you should only take the pill every second day. You are likely to get a palm large area with less sensation on the lower limb. Rarely some patients experience severe foot pain for the first 2 weeks.

Tibiaosteotomi - iBalance

Bowing legs - Varus knees

This demonstrate a person having varus knees and in the right knee you see the line representing the axial load and this is going to the inner site of the knee

X-ray Tibiaosteotomy pre and postoperatively

Tibia osteotomy of a left knee before and 1 month after surgery. The transparent area is the plastic Ibalance wedge - the surgery is also called High Tibial Open Wedge Osteotomy

The picture demonstrates a knocked legged at leff and a bow legged at right

So why chose a tibial osteotomy instead of a knee prosthesis or a uniknee? First of all a knee prosthesis is not a new knee, but a combination of metal and plastic to restore the weared cartilage. A knee prosthesis is a major surgery and it is always better to preserve your own knee if possible. The results after tibial osteotomy seems today to be better than previously and better compared to having a knee prosthesis. One advantage is in average better range of movement. In general 20% says they are happy, 70% are good and 10% is bad and needs a knee prosthesis.

Rehabilitation

Du henvises til genoptræning som typisk starter 14 dage efter operationen.Træningen sigter mod at genoprette bevægeligheden i knæet og genopbygge muskulaturen i benet og genoprette balancen.Dit liv vil i en periode være besværliggjort og du vil i specielt de første 2 uger have svært ved at komme rundt med krykkestokke, fordi du ikke rigtig støtter.Du må først genoptage bilkørsel, når du i relation til benet kan føre bilen sikkert ogdette er typisk 4 uger efter operationen, dog lidt hurtigere for venstre ben end for højre ben.12-14 dage efter operationen skal du have fjernet trådene hos din egen læge. Du skal have taget røntgenbillede 4 uger efter operationen og efterfølgende skal du til kontrol hos mig, for at se hvordan helingen ser ud på røntgenbilledet. Der vil også være en kontrol igen 3-4 måneder efter operationen. Det er ikke ualmindeligt at der går mange måneder inden knæet falder til ro efter operationen.

Complications

Rarely postoperatively infection can occur, but in those cases it is seriously and need instant treatment. In rarely cases will the bone not heal and new surgery is needed.

Internal Bracing for reconstruction of the anterior talofibular ligament (ATFL)

By Lars Blønd

This procedure is indicated for chronic unstable ankle.

Some people have ankle sprains now and then. When the ankle sprains a ligament on the outer site tears and this is painful and most frequently it is the anterior talofibulare ligament that tears (ATFL). The ankle will be weak and there will be a period ranging from days to month to recover - keeping you out from sporting activity.

For some the ankle continues to be unstable and this is naturally very bothersome. Sometimes it is just recurrent sprains, and in other cases the ankle also feels unstable and wobbly, and in those cases stabilising surgery is indicated. A relatively new surgical technique has become widespread very fast, based on its simplicity, the lack of postoperative bracing and the fast recovery and good results. The surgery is based on the traditional Broström operation where the sprain ligament is tightened, but instead of placing the ankle in a brace an internal bracing is used - meaning it is tightened and reinforced by a synthetic ligament.

Sometimes when the ankle sprains, the joint cartilage can get damaged. The symptoms for this is continuous pain and swelling and eventually locking. If this is the situation it will be a good idea to have an arthroscopy in combination with the ankle-stabilising surgery. With the arthroscope the damaged cartilage can be identified and loose cartilage can be removed and eventually stimulation for repair of the lesion can be done (Microfracture also called Steadmann procedure).

If your ankle is unstable it is very important to prevent further sprains by undergoing a physiotherapy-guided rehabilitation program. Afterwards you need to continue yourself with balancing exercises using a tilt or wobble board.

This link is to a video animation of Internal Bracing of the ankle after a Brostöm repair

Professor Gordon Mackay has developed and popularised this procedure, especially in the ankle. Professor Adrian Wilson has also pioneered the use of internal braces in different knee ligaments with the synthetic graft (Fibertape, Arthrex).

Management of SLAP lesions

By Lars Blønd

Description of the disorder - SLAP lesion - Labral tear shoulder

The shoulder joint includes a socket and where the head from the upper arm is running. Around the socket, is a labrum, and this labrum is a structure in between cartilage and ligaments. The labrum acts as a kind of seal, which makes the socket a little wider and is like a package that provides stability to the joint head. On the labrum inserts the long head of the biceps tendon. A pull or twist of the arm, can result in that the biceps pulls the labrum from the socket and this is called a SLAP tear or a labrum tear. See Figures 1 and 2. The typical symptoms are pain and clicking deep in the shoulder, or simply diffuse pain around the whole shoulder. If you have been diagnosed with a SLAP lesion, an shoulder arthroscopy could be needed. The diagnosis can be very difficult to make as the injury frequently can be difficult to diagnose on MRI scans - even MRA (arthrography), but only determined by keyhole surgery.

Purpose of the operation
SLAP lesions may be operated in 3 different ways.

SLAP re-fixation: The labrum is reinserted back by arthroscopic technique (typically for those under 30. The arm must after the surgery be kept in a sling for about 4 weeks) See Figure 1.
Biceps tenodesis: The biceps tendon is released from the attachment on the labrum and reattached again at the top of the upper arm. When biceps no longer pulls in the labrum, the labrum will automatically heal back to the socket rim. (Typically for those over 30 years and the arm must be kept in a sling for about 4 weeks after surgery) See Figure 2.
Biceps tenotomy: The biceps tendon is released from the attachment on the labrum, but unlike the Biceps Tenodesis (the method no. 2), the biceps tendon is not reattached. After the operation used a sling as pain management, but the arm must be well used.

Figure 1 - SLAP fixation

Figure 2 - Biceps tenodesis

Advantages and disadvantages of the three different methods:

SLAP fixation: Typically, a technique that gives good results for those under 30 years. The arm should after surgery be kept in a sling for about 4 weeks
Biceps tenodesis: Typically, a technique that gives good results for over 30 years and the arm must be kept in a sling about 4 weeks after surgery
Biceps tenotomy: Typically, a technique used for those over 50 years. The downside is that some of the biceps muscle can end sitting a little lower on the upper arm, and thereby provide cosmetic nuisance. In addition, it can cause a 15% reduced force in the biceps muscle. The advantage is that after the surgery do not need to use an arm sling and have less pain after surgery and to recover so quickly.