Anatomy of the Knee The Bones of the Knee with x-rays Ligaments of the knee Normal articular cartilage Normal meniscus  Ligaments of the knee Help to stabilize the knee The collateral ligaments run along the sides of the knee and limit sideways motion. The anterior cruciate ligament, or ACL connects the tibia to the femur at the centre of the knee. Its function is to limit rotation and forward motion of the tibia. The anterior and posterior cruciate ligament, or ACL and PCL The PCL located just behind the ACL limits backward motion of the tibia. The ACL and PCL can be visualised well at knee arthroscopy and probed to check their integrity This is  a compilation picture with the arthroscopic pictures superimposed onto an MRI The ACL is seen to sart from the front of the tibia within the knee and run up and out to attach to the back of the femur within the knee   Normal articular cartilage The lining tissue of joints which cushions the knee, covering the bones of the joint Normal meniscus  The lateral meniscus and medial meniscus: these are pads of cartilage that further cushion the joint, acting as shock absorbers between the bones   When we describe the knee, we can divide it into the inside of the knee (medial) and the outside of the  knee (lateral).   Thus there are two menisci, the medial and lateral menisci. p.s. menisci is pleural of meniscus

Meniscal Tears

 

What is the meniscus?

The meniscus is a “C-shaped” cushion pad in the knee between the thigh bone (femur) and the lower leg bone (tibia). It acts as a shock absorber and makes the motion of the knee smooth.

 

How is it injured?

• One way is as part of an injury. This is one of the injuries what can happen when a person injures his/her knee. Usually this is a twisting knee injury with the knee in a bent or flexed position, but can happen in a variety of ways.

• Another way is what happens when meniscal cartilage ages. Young meniscal cartilage is very flexible, like young rubber. As it gets older it becomes like old rubber that has been exposed to the air for years. It becomes hard, less flexible, more brittle and can develop cracks in it like the cracks that develop in old rubber. These cracks in older cartilage are called degenerative meniscal tears. These degenerative tears can occur with or without an injury.

What are the symptoms of a meniscal injury?

They can vary greatly. Symptoms include

• pain

• a feeling of giving way of the knee

• catching and locking

• swelling

How is it diagnosed?
A meniscal tear is provisionally diagnosed by a physical examination and the diagnosis may be supported by an MRI (magnetic resonance imaging). Ultimately it can only be diagnosed definitively by arthroscopy.

What about MRI?

An MRI (magnetic resonance image)  uses a magnetic field instead of x-rays to produce the image.

It allows you to see soft tissues as shadows of different densities. It allows you to see tissues that x-rays cannot show and is extremely useful especially in spines, shoulders, etc.

I frequently do not use MRI to deal with meniscal injuries. The reason is simple. MRI is not totally accurate in diagnosing meniscal tears. I have frequently seen cases where a tear was seen on MRI which on arthroscopy turned out not to be there and the opposite: no cartilage tear seen on MRI, but one found during arthroscopy.

The practical meaning of this is that if an MRI is done and shows a "cartilage tear" the result is that an arthroscopy needs to be done. If however an MRI is negative, but symptoms persist, an arthroscopy often still needs to be done because the MRI could be wrong. So the MRI does not change what needs to be done and at a significant cost.

It may be a waist to do it if it will not contribute usefully to your treatment.

It is however useful in diagnosing other injuries of  the knee such as a ligament rupture and does help  identifying underlying osteoarthritis.

 

 

How is a meniscal tear treated?
A very small percentage of meniscal tears may heal on their own within about 6 weeks. If symptoms continue, then it is unlikely that the meniscal injury will heal and arthroscopy is necessary.

 

 

Bucket Handle Tear of the Medial Meniscus

 

Knee arthritis- Arthroscopic findings

 

Typical findings in moderately severe arthritis. The cartilage is very irregular. Surprisingly, unless there is complete wear down to bone it may be difficult, even with probing of the cartilage, to see how thick the remaining cartilage is. The old fashion x-ray is still an indispensable tool in assessing knee arthritis.

Sometimes you can see the underlying bone, evidence of advanced arthritis

One the cartilage has worn out, the underling bone becomes exposed

The lining tissues of the knee, called the synovium, becomes very inflamed.

Compared to relative mild swelling and redness in this picture

In early arthritis the cartilage becomes loose and breaks away

The shaver, also know as chondrotome is used to remove any loose material in the knee

Loose pieces of cartilage commonly break away from the knee in arthritis

These may grow to become large, called loose bodies

Loose bodies located at arthroscopy can be removed with special instruments

VAPR cleaning of the loose and worn cartilage "The VAPR System's technology creates an ionized vapor pocket at the working tip of each electrode. Tissue entering the pocket becomes instantaneously vaporized, permitting rapid and precise removal of soft tissue"