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Degenerative Hip Problems and Osteoarthritis

First we have to start with the definition and terminology because you will be communicating with us orthopedic surgeons about your patients over the years and the more specific you can be in terms of your findings over the phone the more likely you are to get the patient referred.

We need to go over some of the basic anatomical terms for motion of joints. This will all be with respect to the hip. Hip abduction is motion away from the midline of the body. The body is sectioned in the mid-line, so for the hip this is abduction. For the shoulders, the same. Adduction is moving towards the midline of the body. Normal range of motion is anywhere from 45 to 55 degrees of the abduction and 20 to 30 of the adduction in a normal hip, and you always compare a joint to the contralateral joint, assuming it is normal and non-symptomatic.

We always have basically internal control to test with. There is a wide variation based on patient’s flexibility and their joint design and how much motion they will have in these directions. When there is a difference between the two joints, it often times is an indicator of something going on. In the other plane, flexion extension, hip flexion is motion anterior to the midline of the body, extension is posterior. Normal hip range for flexion is approximately 135 degrees, it depends on the body habitus, if somebody is morbidly obese they will not be able to reach that because they will hit their abdomen with their thigh. 

Hip extension, normally approximately 30 degrees. The combination of the extension and the flexion gives you the full range of motion. Now if we talk about the other plane and we split the patient down the middle, this plane here that we are looking at, if, the joint is rotating away from that plane in the midline that is external rotation, and in the opposite direction, towards the midline that is internal rotation. With the hip examination, I always find that rotation is the first to be affected by an arthritic process or degenerative process. It is always very useful and very informative to check the internal and external rotation in both hips.

Now let’s talk about what you can palpate in the average patient. If you have a very overweight patient you wont be able to get these landmarks and you will sort of be left without these specifics of this exam,. But the palpable landmarks about the pelvis, the anterior superior iliac spine, ASIS, which is right here, that is basically the anterior part of the iliac crest. You can palpate it subcutaneously around until it disappears in the back where the posterior superior iliac spine is. The SI joints are almost always subcutaneous and there is a little skin dimple right over them. We have the iliac crest that you can palpate, the pubic symphysis is anterior in the midline, usually palpable, more difficult with this patient in a sitting position or with the hip flexed.

Frequently hip pathology in particular, end stage or severe osteoarthritis will lead to shortening of the extremity. The reason that occurs is you normally stand on your bone covered by a cartilaginous cap which has a certain length or thickness. In arthritis that is stripped away and the femoral head then starts to grind bone on bone, that loses you about 3/8 of an inch in height on that extremity. Then if it goes unchecked for a number of years, patients will actually destroy the bone itself and that all causes the femur to migrate proximally and it makes the leg shorter. There is a difference between apparent leg length discrepancy and a true leg length discrepancy and we will go over this. Apparent is what it sounds like, the legs are really equal but the patient has their pelvis tipped so instead of being flat like this, the pelvis is tipped up at an angle.

This is a dynamic obliquity when the muscle that you use to pull your leg off to the side becomes weakened, over time as you walk, that muscle becomes ineffective and it allows the pelvis to drop, when you take your foot off the ground. You raise your leg up off the ground, the pelvis on that side droops and it gives you a waddling type gate.

Finally, tendinitis and bursitis on your examination, how to differentiate that from osteoarthritis. This is much more common than arthritis and many patients will come in complaining of hip pain that actually have bursitis of the tendon. Pain and crepitation over the greater trochanter on the lateral side of the hip is pathopneumonic for trochanter bursitis. They will often say when they get The iliopsoas is thankfully rare and difficult to treat. It is in the medial groin. The figure 4 position, where you take the patient’s right leg, put the ankle over the left knee and push down on their knee to make a figure 4, which is why it is called that, that will stretch the psoas and reproduce their symptoms.

Now to talk a little more about osteoarthritis. Approximately 300,000 total hip replacements are done in the U.S. every year. Most of them are done through osteoarthritis. It is extremely common, our population is aging. In addition, our technology is improving and we are doing them on younger and younger patients that we previously told had to wait and use a cane and be disabled. So, this operation is happening more frequently and is commonly done in every community hospital basically in the country, I am sure.

Patients are usually over 50 with osteoarthritis. Now this is different then posttraumatic arthritis, arthritis from congenital hip.

Causes for arthritis, idiopathic primary means no underlying pre-disposing causes that is just what I was talking about. Secondary could be due to osteonecrosis which is loss of the blood supply to the femoral head, congenital hip dysplasia which this is an example of, this is at infancy. The hip is not yet developed but the warning sign is that this is not pointed to the center of the pelvis, if it goes untreated in the early stages, this is what happens, the hip develops in an abnormal position, it is not in a socket, there is a pseudoacetabulum here which isn’t suited for walking, that leads usually by age 40 to very severe pain and is a major reconstructive challenge because the nerves and the vessels, and the muscles have never, ever been in the correct position. So they are quite contracted. The nerves are higher risk when you reconstruct these patients. There is much more complication problems because the bones are shaped abnormally and normal prosthesis don’t fit. The point is, don’t let this happen, get a good screening in the nursery and get that hip in the care of a specialist who can get it back to develop normally and its completely avoidable.