Decreased Serum Pituitary Adenylate Cyclase Activating Polypeptide (PACAP) Levels May Reflect Disease Severity in Patients with Non-traumatic Osteonecrosis of Femoral Head

To investigate serum pituitary adenylate cyclase activating polypeptide (PACAP) levels in relation to disease progression in patients diagnosed with non-traumatic osteonecrosis of femoral head (ONFH). A total of 102 non-traumatic ONFH patients and 95 healthy controls were enrolled in this study. Serum PACAP levels were examined using enzyme-linked immunosorbent assay (ELISA). Radiographic progression of ONFH was detected using the Association Research Circulation Osseous (ARCO) classification system. Harris hip score (HSS) and visual analogue scale (VAS) were analyzed to understand clinical severity. Serum levels of the ONFH marker IL-33 and β‐CTX were also detected. ROC curve analysis was performed to investigate the potential diagnostic value of serum PACAP in the radiographic progression of ONFH. Serum PACAP levels were significantly decreased in non-traumatic ONFH patients when compared to healthy controls. ARCO stage 4 showed markedly lower serum PACAP levels than stage 3. ARCO stage 3 had significantly decreased serum PACAP levels compared to stage 1/2. Serum PACAP levels were negatively correlated with the ARCO classification. In addition, serum PACAP levels were positively associated with HSS score and negatively related to VAS score. Last, PACAP levels were negatively correlated with serum IL-33 and positively associated with β-CTX. ROC curve analysis indicated that PACAP may serve as an early indicator for the radiographic progression of ONFH. Reduced serum PACAP levels may reflect disease severity in non-traumatic ONFH patients.