By: Terry R. Yochum, DC, DACBR, Fellow, ACCR and Michael S. Barry, DC, DACBR
A 50-year-old male patient presents with pain affecting his first metatarsal and interphalangeal articulation of the great toe. What is your diagnosis?
Figure 1. Diagnosis: Gout. Observe the tophaceous marginal erosions on the lateral aspect of the distal phalanx of the great toe. Similar erosions are also seen on both the medial and lateral head of the first metatarsal and base of the proximal phalanx. There is also significant soft tissue swelling with some increase in density as a result of gouty tophus formation. Note the relative preservation of the joint spaces in the first metatarsophalangeal and distal interphalangeal articulations. This is a hallmark radiographic sign of gout. There is a striking lack of osteoporosis with this degree of erosion, which is also a cardinal feature of gout versus inflammatory arthritis.
Gout has been known throughout history, often afflicting famous and influential people who subsequently have become favorite subjects of caricature and satire. Gout is often seen as a symbol of retribution of excessive human indulgence. The term gout, derived from the Latin word “gutta” (a drop), reflected the Hippocratic belief that the disease was caused by a poison falling drop by drop into the joint.
Onset of disease is usually in a male patient over 40 years of age, with peaks in the fourth and fifth decades. Males suffer from this disease approximately 20 times more commonly than women.
The inciting inflammatory agent is the crystal of sodium monourate. Hyperuricemia is the necessary precursor to the development of these crystals. Uric acid is derived predominantly from the breakdown of the purine nucleic acids adenine and guanine.
Distinctively, radiographic findings lag behind clinical manifestations with a latent period of 5 to 10 years. The most distinctive location for gouty articular changes is the first metatarsophalangeal joint of the foot (Fig. 2).
General features include dense soft tissue tophi (Fig. 3), preservative of joint space, and bone erosions creating the classic “overhanging margin sign” (Fig. 4). The bone density is usually normal, showing no signs of osteoporosis to suggest inflammatory arthritis.
While the foot is the most common site, other locations, such as the hands, wrist, and knees, may be involved. Spinal involvement is exceptional, and in approximately 15% of individuals the patient may have bilateral sacroiliac erosion (Fig. 5). The most frequently recorded radiographic signs in the spine are that in the cervical spine in the upper cervical area causing odontoid erosion and atlantoaxial subluxation and instability.
- Yochum TR, Rowe LJ. Essentials of Skeletal Radiology, 2nd ed. Baltimore, MD: Williams & Wilkins, 1996:929-936.