I define hip hiking as active and muscular driven.
Upslip I define as subtle because there is remarkably little vertical mobility in the sacroiliac by design, thus, even true instability seldom manifests as Upslip. Upslip will have an absence of superior and of inferior passive joint motion testing of 10 to 40# varying client to client. The sacrotuberous ligament is lax in an Upslip, not so in hip-hiking.
Posted in manual therapy blog,
https://www.facebook.com/groups/288423771210717/293725407347220/
lots of interesting topics. Jonathan George started it recently. Great thinker, great clinician somewhere in New Hamshire? Where are you Jon?