Heterotopic ossification of the hip as a complication of tetanus.

Heterotopic ossification is a very rare complication of tetanus. In one case heterotopic ossification occurred around both hip joints. The values of serum creatine phosphokinase had been elevated significantly when the patient had major muscle spasms. The elevation in serum alkaline phosphatase values following that in creatine phosphokinase values persisted for about four weeks. Partial resection of the bone mass about the right hip joint resulted in a satisfactory improvement in performance of daily activities. The specimens incised at operation revealed both lamellar and woven bone surrounded by fibrous connective tissue. Very near the bone mass were severely degenerated muscle fibers. In addition, evidence suggesting metaplasia of fibroblasts to osteoblasts was seen in some areas. Clinical and laboratory data indicate trauma as a main etiologic factor of heterotopic ossification following tetanus. Heterotopic bone formation should be considered if elevation of the serum alkaline phosphatase values persists beyond the period of elevation of serum creatine phosphokinase values. Artificial ventilation may be beneficial for preventing heterotopic ossification following tetanus if it is administered before there is significant elevation of the serum creatine phosphokinase values.