Transphyseal involvement of pyogenic osteomyelitis is considerably more common than classically taught

OBJECTIVE. Radiologists are taught that pyogenic osteomyelitis in children rarely crosses the growth plate because terminal vessels of nutrient arteries loop at the physis, predisposing the metaphysis to hematogenous infection. However, we note that MRI frequently shows osteomyelitis involving both sides of the physis. The purpose of this article is to document our observation that pyogenic osteomyelitis crosses the growth plate more frequently in the pediatric patient population than is classically taught. MATERIALS AND METHODS. All pediatric patients (age, 2-16 years) with clinically suspected osteomyelitis from 2004 to 2009 were reviewed for transphyseal disease on a consensus basis. To reveal the statistical significance, we applied a z test to our results. We quantified rare as 20% or less and used a z test to determine whether 27 of 32 (81%) differed from rare. RESULTS. Of 32 subjects, 81% showed transphyseal infection. In our study, the z test revealed that transphyseal infection occurred significantly more often than what would be considered rare (z = 4.75, p < 0.01). CONCLUSION. In our pediatric patient population, we have documented a higher frequency of transphyseal osteomyelitis (81%) than metaphyseal osteomyelitis in pyogenic infections. When our findings are statistically compared with an expected rate of 20%, they cannot be attributed to chance alone. This raises some doubt regarding the conventional understanding of pediatric pyogenic osteomyelitis.