As the fictional presentation below will show, x-rays, MRIs, and CAT scans are not very helpful in diagnosing joint pain (including backs). It was just easier to construct a story around knees. Enjoy.
Dr. Evans used the remote to turn down the lights in the auditorium, and then turned on the first slide in his presentation. “I’m going to show you three sets of bilateral knee x-rays,” he said. “One set is from someone with severe arthritis, another from a person who has severe, incapacitating knee pain, and another from a marathon runner. I want you to tell me which set of x-rays you think goes with each patient history.”
The first set of x-rays towered over Evans, the projector showing twelve foot high x-rays on the screen. In the shadows, Evans pointed his red laser at the x-rays, specifically at the joints. “You can see here nice smooth cartilage on both femurs and both tibia in the anterior-posterior views. Lateral views and tunnel views show no abnormal bone, bone spurs, or unusual calcifications. Anyone see anything else I should point out?”
There were no suggestions. Evans continued, “Any of you think this is our marathoner?”
The show of hands was almost unanimous, with the exception of a few students who had been fooled by Evans in the past. “Okay, the second set,” Evans said, pushing a button on the remote. Two more large knee x-rays replaced the first ones on the towering screen. “This left knee appears to be normal.” Evans played the pointer across the joints. “The right is a disaster, though. Look. No joint space medially. Large bony spurs medially, with smaller spurs laterally. Could this be our patient with severe, incapacitating knee pain?” There was a murmur of assent, again with a couple students demurring.
The third set of knee x-rays appeared on the screen. “Now, this patient has narrowed joint spaces in both knees. There are bony cysts underlying the cartilage in both joints, and small spurs medially and laterally in both knees. Is this the arthritis?”
“That wasn’t so hard, professor,” one of the skeptical students suggested. “Are we treating x-rays now?”
Evans smiled. The student had heard Evans harp on just this point in the past. “No, Tony, we are not treating x-rays, as you well know. Let’s look at these again, and I’ll point out some things you, as a group, may have missed.”
The first set of x-rays magically reappeared. “As I said, these are totally normal x-rays. However, this is not our marathoner. It is our patient with severe, incapacitating knee pain. What I did not point out, and what you did not see since no one else pointed it out, was this.” Evans used the pointer to outline the soft tissue surrounding the knees. The gray shadow was that of a huge, obese individual. “Arthritis doesn’t show up on x-ray for years. It takes sometimes a decade for cartilage and bone changes to be visible. This patient never does any exercise, and eats way too well. As a consequence, he weighs 373 pounds. The compression of his joints will eventually destroy the cartilage. His knees already hurt terribly. He uses that as an excuse not to exercise. Soon he will have severe osteoarthritis. Not only will his x-rays remain normal for several more years, but all his lab tests will be normal for several more years. Then he will become a Type II diabetic. In order to save his knees and preserve his life, he needs to ignore the pain, exercise and lose weight.”
“The second set of x-rays,” Evans continued, pointing to the x-ray with one normal knee and one severely arthritic knee, “are from a patient with severe osteoarthritis. He had a meniscus tear and a destroyed anterior cruciate ligament while playing football in high school. This was in the days before anterior cruciate repair. The medial meniscus was removed; the knee has collapsed on itself. But, and this is a big but, this patient has very little pain. He was told to keep exercising and to keep his leg strong, which he has. He runs 4-5 miles 2-3 times a week, occasionally taking Ibuprofen or Naprosyn when he overdoes it. Exercise protects joints, if it’s not overdone.”
The projector advanced to the third slide. “Here is our marathoner. Notice, he has mild osteoarthritis in both knees. He has absolutely no pain in his legs. The x-rays were taken as part of a knee study in geriatric patients, which will be published in an orthopedic journal next year. I shouldn’t say he has absolutely no pain. He does complain about knee stiffness after 3-4 days if he is unable to run. Again, exercise protects joints.”
Evans eyed the students with a smile. “Okay, anyone up for treating the x-rays?” There were no hands raised. “Good. X-rays confirm diagnoses. They do not make diagnoses.” He paused to make certain the point was absorbed by all.
“Now we are going to look at another set of x-rays. I’ll give you a history and you tell me what the x-rays confirm. Fair enough?” Most of the students nodded, with the exception of the skeptical students.
This is a 19 year old volleyball player. She missed half the season with a severe ankle sprain. After returning to the sport, she has practiced for one week and now complains about severe knee pain when getting up from a seated position or running down hill. The first x-ray flashed on the screen was a chest film. With the students’ new found appreciation of soft tissue shadows, it was apparent to most of them that this patient was tall, thin, and had large dense breasts. “Okay,” Evans laughed and spoke in a high falsetto voice, “Doctor, my knees are down here!” The class laughed.
Evans hit the remote and a set of knee x-rays appeared on the screen below the chest x-rays. “They are normal,” a bewildered student said.
“Correct,” Evans agree. “But what does that confirm?”
“Nothing,” another suggested.
“Wrong,” said Evans. “It confirms she has Patello-Femoral Syndrome. I gave you the classic history: athlete sidelined for an injury, pain on rising from a seated position, and pain running downhill. The x-ray shows there are no other lesions that might cause similar symptoms. Now you could order an MRI to look at the soft tissues. Would you want to? MRIs are expensive.”
“Be better to treat her for PFS. Save the MRI in case she doesn’t improve,” one of the skeptics suggested.
Evans beamed. “Don’t treat x-rays, MRIs, CAT scans, blood tests, etc. Use these tests to prove or disprove the diagnosis if the treatment isn't working.”
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