Figure 2.

Strobe flow chart shows patient selection. Of the 250 patients assessed for eligibility, 16 were excluded from this study because of their age (<18 years) and 18 because they did not have samples available for the analysis. Two hundred and sixteen patients were reviewed and stratified according to their osteonecrosis status. Of these, 150 age- and sex-matched patients were identified: 62 patients had a history of osteonecrosis and 15 patients had incident osteonecrosis during follow-up, while 73 patients remained free from osteonecrosis. Four patients with incident osteonecrosis were excluded from the final analysis since they either had only samples collected before or after the osteonecrosis event. Another patient also had osteomyelitis and was therefore excluded.