Marcin Tyrakowski1, Dominika Wojtera-Tyrakowska, Kris Siemionow. 1. *Department of Orthopedics, Pediatric Orthopedics and Traumatology, The Centre of Postgraduate Medical Education in Warsaw, Otwock, Poland †Department of Orthopedic Surgery, University of Illinois at Chicago, Chicago, IL; and ‡Faculty of Mathematics and Computer Science, Adam Mickiewicz University, Poznan, Poland.
Abstract
STUDY DESIGN: Radiographical laboratory study. OBJECTIVE: To analyze the influence of pelvic rotation on pelvic incidence (PI), pelvic tilt (PT), and sacral slope (SS) measurements and to present a geometrical method of calculating the angle of pelvic rotation on lateral radiographs. SUMMARY OF BACKGROUND DATA: PI, PT, and SS may potentially be dependent on the axial rotation of the pelvis while acquiring the radiograph. However, no study investigating this problem has been published. METHODS: One radiological pelvic phantom was used to obtain 1 anteroposterior and 10 lateral calibrated radiographs with axial rotation of the pelvis from 0° to 45° at 5° intervals. PI, PT, and SS were measured. The maximal angle of rotation that changed PI, PT, or SS measurements of less than 6° (compared with these measured on the radiograph with rotation of 0°) was considered as acceptable.Linear distance between the centers of the femoral heads (A) was measured on the anteroposterior radiograph. Horizontal distances between the centers of the femoral heads (B) were measured on lateral radiographs. The angles of rotation (α) of the pelvis on each radiograph were calculated: α= arcsinB/A. Agreement between the measured and the calculated angles of rotation of the pelvis was assessed. Intra- and interobserver reliability of the proposed method of calculations were tested. RESULTS: The maximal acceptable angle of rotation of the pelvis was 30°. There was an excellent agreement between the measured and the calculated angles of rotation of the pelvis (intraclass correlation coefficient = 0.99; median error for a single measurement [SEM] = 0.3°). Excellent intra- and interobserver reliability of the method was revealed (intraclass correlation coefficient = 0.99 with SEM = 0.5° and intraclass correlation coefficient = 0.99 with SEM = 0.7°). CONCLUSION: PI can be influenced by rotation of the pelvis. The acceptable maximal angle of rotation for reliable measurements of PI, PT, and SS was 30°. The angle of rotation of the pelvis on the lateral radiograph can be reliably calculated. LEVEL OF EVIDENCE: 3.
STUDY DESIGN: Radiographical laboratory study. OBJECTIVE: To analyze the influence of pelvic rotation on pelvic incidence (PI), pelvic tilt (PT), and sacral slope (SS) measurements and to present a geometrical method of calculating the angle of pelvic rotation on lateral radiographs. SUMMARY OF BACKGROUND DATA: PI, PT, and SS may potentially be dependent on the axial rotation of the pelvis while acquiring the radiograph. However, no study investigating this problem has been published. METHODS: One radiological pelvic phantom was used to obtain 1 anteroposterior and 10 lateral calibrated radiographs with axial rotation of the pelvis from 0° to 45° at 5° intervals. PI, PT, and SS were measured. The maximal angle of rotation that changed PI, PT, or SS measurements of less than 6° (compared with these measured on the radiograph with rotation of 0°) was considered as acceptable.Linear distance between the centers of the femoral heads (A) was measured on the anteroposterior radiograph. Horizontal distances between the centers of the femoral heads (B) were measured on lateral radiographs. The angles of rotation (α) of the pelvis on each radiograph were calculated: α= arcsinB/A. Agreement between the measured and the calculated angles of rotation of the pelvis was assessed. Intra- and interobserver reliability of the proposed method of calculations were tested. RESULTS: The maximal acceptable angle of rotation of the pelvis was 30°. There was an excellent agreement between the measured and the calculated angles of rotation of the pelvis (intraclass correlation coefficient = 0.99; median error for a single measurement [SEM] = 0.3°). Excellent intra- and interobserver reliability of the method was revealed (intraclass correlation coefficient = 0.99 with SEM = 0.5° and intraclass correlation coefficient = 0.99 with SEM = 0.7°). CONCLUSION: PI can be influenced by rotation of the pelvis. The acceptable maximal angle of rotation for reliable measurements of PI, PT, and SS was 30°. The angle of rotation of the pelvis on the lateral radiograph can be reliably calculated. LEVEL OF EVIDENCE: 3.
Authors: Stefano Negrini; Sabrina Donzelli; Angelo Gabriele Aulisa; Dariusz Czaprowski; Sanja Schreiber; Jean Claude de Mauroy; Helmut Diers; Theodoros B Grivas; Patrick Knott; Tomasz Kotwicki; Andrea Lebel; Cindy Marti; Toru Maruyama; Joe O'Brien; Nigel Price; Eric Parent; Manuel Rigo; Michele Romano; Luke Stikeleather; James Wynne; Fabio Zaina Journal: Scoliosis Spinal Disord Date: 2018-01-10
Authors: Cort D Lawton; Bennet A Butler; Ryan S Selley; Kathryn A Barth; Earvin S Balderama; Tyler J Jenkins; Ujash Sheth; Vehniah K Tjong; Michael A Terry Journal: J Orthop Date: 2020-04-01
Authors: Marek Jóźwiak; Michał Rychlik; Bartosz Musielak; Brian Po-Jung Chen; Maciej Idzior; Andrzej Grzegorzewski Journal: BMC Musculoskelet Disord Date: 2015-02-25 Impact factor: 2.362