Another important differential finding is the rarity of infection in the skull, ribs, spine, and pelvis. At least one patient with infection of the facial bones has been recorded, as has a patient with thoracic vertebral involvement. Deformity of the pelvis with flattening and distortion of the acetabulum is slightly more frequent because the hip joints do not escape the common pattern of effusion and destruction, and weight-bearing may be allowed too early. The end result is as variable as the disease. The new bone may slowly resorb and clinically patients may return to normal with remarkably few residual radiological changes. Yet other less fortunate patients remain with ankylosis of the joints, malformation of the bones even when the joint space remains intact, flared joints, and subluxations (Fig. 40.7).

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Fig. 40.7A-F. The end results of childhood osteomyelitis variolosa. (A) This child has not stopped growing, but there are already deformities in the hand which will become more marked as growth continues. The first metacarpal is shortened and the carpal bones disrupted. There is also a defect in the metaphysis of the radius. (B) This African man had smallpox when he was a small child. As a result he has asymmetrical deformities of both hands and both elbows, particularly the left. (C, D) The hands of the same patient as in B show that the metacarpals are the most severely affected: all except the fifth left are shortened and have marked metaphyseal widening. There are similar but less severe changes in some of the phalanges. Degenerative arthritis is almost certain to develop. (E, F) The hands of another smallpox survivor. The second and fifth left metacarpals have been severely damaged, but there is less metaphyseal flaring than is seen in C and D.