DETERMINING THE SI JOINT AS SOURCE OF PAIN: CLUSTER OF VAN DER WURFF In order to determine if you patients's pain is coming from the SIJ you can perform the cluster of van der Wurff. With 3 or more out of 5 positive tests, the SIJ is probably the origin of pain (Sn: 85%, Sp: 79%) and vice versa (less than 3 positive tests --> SIJ pain less probable). So 3 or more positive tests results in a LR of 4.05, while 2 or less positive tests result in a LR- of 0.19. #SIJprovocation #SIJ | Physiotutors