Diplomate, Board Certification of Emergency Medicine
Chairman, Department of Emergency Medicine Ma'ayenei
Hayeshua Hospital
Bet you didn't think about the miracle of your joints today.
Let's take one in particular, the knee as an example.
The knee does not work as a ball-in-cup-like mechanism,
which is how the shoulder and the hip are constructed. The
knee needs the ultimate in stability since the whole body's
weight rests on it yet at the same time it must be mobile
enough to allow you to bend, walk, and run. It also must be
cushioned enough that bone does not grind against bone.
Let's look closer at this miracle.
The knee supports the biggest bone in the body, the femur.
The tibia accepts the femur's weight, and to make sure that
the whole joint is protected from things that could
penetrate the joint and cause vicious infections (as we
often lean and fall on our knees) there is a little bone on
our knee cap called the patella. The joint is below the
patella and is enclosed in a fibrous capsule. Cushioning is
very important in the knee because it supports the whole
body on two legs, not four like with animals, and the bones
must be smaller to allow us mobility and stability.
To do this the femur inserts into two U-shaped fibrous rings
called cartilage. Also, surrounding the joint are four
little bags of fluid called bursae. In addition, inside the
joint itself is a small amount of fluid called synovial
fluid. The last two things can easily become inflamed or
infected, while cartilage can be torn.
For mobility, there are of course muscles that move the
joint, but mostly only in two directions, that is bending
and straightening the leg. This is accomplished by
ligaments, which are hard stringy straps. In the knee there
are four. People exposed to violent stresses, such as in car
accidents or sports, can tear these. Worst of all is when
they all tear, such as in a dislocation, which is a very
serious problem, seen in the emergency room after high speed
accidents.
Fortunately, with the exception of fractures and
dislocations, most of the problems that occur with the knee
can be dealt with by rest and local treatments. Occasionally
we must stick needles into the knee to drain fluid or inject
medications but the knee does a wonderful job healing
itself. In the rare cases it doesn't, we can stick a little
scope in the knee and actually see (and treat) what is going
on. Even in the worst case where the knee is destroyed from
years of usage, we can replace the whole joint.
This is all an introduction to a discussion we will have on
joint problems which is call rheumatology, which is in the
realm of both orthopedists and rheumatologists. More in two
weeks. Write me in care of the Yated.
A message from Glaxo, sponsor of this column.
Pneumonia season is here and Zinnat and its intravenous
equivalent Zinacef can be life saving for elderly people
with this disorder. Indeed, what formerly need a prolonged
hospitalization can often be treated with fewer days with
this medication.
