title: Expanding on the term "balloon" sign.
authors.affiliation: Department of Neurologic Surgery, Mayo Clinic, Gonda 8-214, Rochester, MN, USA. spinner.robert@mayo.edu.|Department of Orthopedics, Mayo Clinic, Rochester, MN, USA. spinner.robert@mayo.edu.
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Spinner
authors.affiliation: Department of Orthopedics, Mayo Clinic, Rochester, MN, USA.
authors.forename: Nicholas M
authors.initials: NM
authors.lastname: Desy
authors.affiliation: Department of Radiology, Mayo Clinic, Rochester, MN, USA.
authors.forename: Kimberly K
authors.initials: KK
authors.lastname: Amrami
authors.affiliation: Bone and Joint Diseases Research Center, Department of Orthopedic Surgery, Chamran Hospital, Shiraz University of Medical Sciences, Shiraz, Iran.
authors.forename: Amir R
authors.initials: AR
authors.lastname: Vosoughi
authors.affiliation: Reparto di Chirurgia Ortopedica, Clinica Luganese Moncucco, Lugano, Switzerland.
authors.forename: Kaj
authors.initials: K
authors.lastname: Klaue