Get to grips with the subtle anatomical details that help you to both really understand modern 'manual' techniques of physiotherapy and also to understand some of the procedures of 'salvage' when scar tissue demands such surgery.
Transcript of the video
This lecture is about the important soft tissues that 'facilitate' movement. Some of these will have actual lubricating fluid inside them, while others make it easier for the tissues to move when the knee is bent and straightened, allowing soft tissues like muscles and tendons to slide in relation to one another. Specifically here I am referring to those tissues that are outside of the capsule.
In the previous section we saw how the two central heads of the quads muscles come together to form the patellar tendon. Here is a sideways look at that. What I would like you to notice is that there is a fine tissue network between the two muscle heads. The tissue is called 'fascia'. This allows the muscles to be able to contract in relation to one another. Fascia also exists around the hamstrings muscles at the back of the knee.
The next of the soft tissue structures that facilitate knee movement are little envelopes that are lined by cells that produce small amounts of a slippery lubricating fluid. These envelopes are called 'bursae'. Normally the walls of the bursae can rub together as the knee moves, and they cause no problem and the person is utterly unaware of them. Sometimes, under abnormal conditions, there is inflammation in a bursa and it fills up with tense fluid, making the bursa area hot and painful. Such a bursa can also become infected, although this is infrequent. If there has been inflammation in a bursa, and the fluid becomes resorbed, any residual fluid can become sticky and gum the walls of the bursa together, and that is one of the causes of knee stiffness after injury or surgery.
Several bursae exist in relation to the patella - one directly in front of it, and others related to the tendon below it. A superficial one under the skin in front of the patella is called the 'pre-patellar bursa', and when it is inflamed the condition is commonly called 'housemaid's knee'. A superficial one under the skin in front of the patellar tendon is called the 'superficial infra-patellar bursa’, and when it is inflamed it is commonly referred to as 'plumber's knee' or 'clergyman's knee'. Deep to the same tendon is another smaller bursa called the 'deep infrapatellar bursa'. All of these can become implicated in knee stiffness after injury or surgery, as will be explained later in the course.
The next structure I want to discuss is sometimes referred to as a bursa, and sometimes a pouch, because its anatomy varies. It is situated deep to the quadriceps tendon, above the patella. It looks just like a capsular fold, as we discussed when we talked about the capsule. But sometimes it develops more like a sealed bursa, not communicating with the joint space. Normally, however, it does communicate with the joint space, and surgeons commonly refer to it as 'the supra-patellar pouch'.
The importance of this pouch in terms of knee movement is that it allows the capsule considerable slack, so that the hinge joint within the capsule can bend and straighten. If the knee is swollen and the pouch filled with fluid, movement will be more difficult. If the fluid has been resorbed and the walls of the pouch gummed together with sticky residue, then bending the knee is very difficult and very painful. If the sticky adhesions turn into scar tissue, then the front and back walls of the pouch effectively seal together, and flexion is severely affected and pain on bending is excruciating.
You can see the bright yellow fat pad. Look at the gap where it snugs in front of the tibia. This part is usually free to move, and the space is called the ‘anterior interval’. This is another place where the opposing structures can become gummed together, limiting movement of the patellar tendon.
Behind the femur is another significant area, where the capsule normally has slack. This area can have adhesions and the capsule can shrink here - the region is known as the ‘posterior capsule’.
That covers most of the really important soft tissue structures that together facilitate movement of the knee. There are others that matter, but they are impossible to show with this illustration, and will be mentioned later on. So that will do for now, and it gives you some background into topics that we will discuss in more depth as we progress through this course.
In the next lecture we are going to be talking about flexion, and discussing the muscles that power flexion and the muscles that allow flexion and how they work together.