Reading Your Foot X-ray

reading x-rays requires years of clinical skill and exposure, but is there a reason why patients cannot understand common problems like arthritis of the big toe?

Arthritis and the Foot X-ray

When I read a post on Facebook, a blogger (let's call him/her DC), asked the following question: 'Can anyone tell me how to interpret if I have arthritis in the toe joint?'

The blog post opened up several questions.

1. Should patients need to ask questions, and is this not the responsibility of the clinician / surgeon?

2. Non-qualified people pitch in often with spurious and inaccurate answers.

3. Soon the original blogger is overwhelmed and goes back to the surgeon only to be less welcomed. Don't you trust me!!

4. This article is about a bunion foot X-ray and arthritis

Now I'm a big fan of patients being educated, and having X-rays also is useful just in case you need a second opinion. We live in a different age to when I started practice as a podiatrist and later foot surgeon.

Self-Education and Assistance for Bunion Surgery

DC ideally should seek closer rapport with the surgeon, but there is no reason not to educate oneself and to be honest you can just ask Google AI which it is pretty reliable, but chances are that the information will be less comprehensive... this is where I come in.

We need to start with the default - DC shows one x-ray. This provides limited information. We need three views because if we don't have a scan i.e MRI - then we need to create a 3D view as best we can.

The three views:

1. Dorsi-plantar [DP] (often called anterior-posterior or [AP]) - this shows the foot from the top.

2. Lateral - this shows the foot from the side.

3. Medial-oblique [MO] - this shows the foot between DP and lateral at 45 degrees.

The three standard views ordered of the foot showing bones and alignment.

ABCDE - a format for reading an X-ray

The format clinicians use for interpreting the foot x-ray follows the pattern A-B-C-D-E

A = Alignment so we can look at any deformity.

B = Quality of bone.

C = Cartilage and soft tissue.

D = Density of bone.

E = Everything else.

Foot specialists who may be registered as doctors (USA) or misters (UK) train to read X-rays by taking classes and clinical exposure during training and placements. We learn about anatomy, pathology and medicine and so X-rays are only a part of our diagnosis. An X-ray aids but does not define diagnosis alone.

A fracture (break across the bone) is obvious, but in the foot pound to a penny, patients will ask what is that bone and should it be there? We are talking sesamoids - two permanent bones that are akin to the knee cap and are important for big toe movement and efficiency.

Let's look at DC's X-ray...

DC's X-ray left side. Normal X-ray right side. See text for more information.

Remember, DC asked about arthritis.

A - alignment. The big toe has a small deviation called hallux valgus. Note the end first toe bone is closer to the second toe bones than the normal foot.

[2] the sesamoid bones x2 are present but they are displaced toward the second metatarsal which shows the extent of the deformity in the big toe. One of the sesamoids may have been divided, also know as bipartite and is normal. The normal X-ray shows how sesamoids should be aligned. Does her X=ray shows sign of arthritis - NO.

B - The bone edge [3] has expanded and this is the bunion also known as an exostosis. Look at the faint outline or soft tissue shape of the foot. This looks wider. Is this severe - NO. Does it hurt - well that's a question for the surgeon and patient to consider.

C - Cartilage and soft tissue. All looks good.

D - Bone quality looks good so healthy calcium diet and no fractures.

E - Nothing of concern although I would want a lateral and MO view just to be certain.

There is some sclerosis at the base of each toe bone. Look to see the heavier whiteness present. This is normal and comprises denser bone because of the impact of forces naturally occuring.

Now that we have considered the ABCDEs the clinican will use the patient history to determine to best approach to DC's problem.

The Question of Arthritis from an X-ray

Can you tell arthritis from an X-ray - YES. Arthritis as a term is not accurate and we prefer arthrosis. i.e a condition affecting joints through wear and tear or disease. The commonest condition is wear and tear. Arthritis does not determine the type of arthrosis.

The first toe joint [1] has reduced black space so sometime the bones have no gap. This is where the MO and lateral views come in as a DP view is not always conclusive.

Under the 'E' of ABCDE, we can consider various types of arthritis.

Read more about arthritis in feet. Arthritis and the Big Toe

There are two elements that concern surgeons. Pain and lack of movement of the big toe.

I have personally corrected a big toe and the patient's hip pain has disappeared therafter, proving we walk differently with pain and stiffness.

If the joint has no gap, the flushing fluid (synovial fluid) within the joint cannot maintain healthy cartilage. However, this is more of a problem with hallux rigidus and hallux limitus. Hallux valgus (bunions) often move quite well, but not in the usual direction had the deformity not been present. The sesamoid position rotates around rather than sliding sideways.

Inside a good many joints, cartilage loss is apparent. You cannot pick this up on a simple X-ray because cartilage shows as black, not white. The white is due to the absorption of X-rays picking up calcium and phosphate salts in the bone. When the bone is a poor quality, the density becomes more (osteo) porotic.

Conclusion

X-rays are valuable and a first line diagnostic tool when considering treatment. Patients can only really understand the meaning of X-rays from their clinician because of the many complexities.

You can read more about bunions and self-help from David R. Tollafield on this site or by purchasing on of his patient books available as an epub or paperback.

Read more from the author about Health Communication

Three books on the big toe and its problems from self-help to surgery. Buy today

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