INTRODUCTION: Anteroposterior pelvic radiographs are routinely used to monitor cup orientation in total hip arthroplasty (THA). Analysis of planar radiographs leads to a certain degree of measurement error for the cup anteversion (AV). With the current study, we wanted to clarify whether planar radiography can be used for accurate evaluation of the THA position. MATERIALS AND METHODS: The postoperative orientation of pelvic implants in 42 patients was analyzed according to five documented mathematical algorithms using planar radiographs. Postoperative computed tomography (CT) pelvis scans were available for all patients. A CT-based navigation system was used to determine AV. RESULTS: The comparison showed that all five formulas presented substantial variations for the AV angle. Of these, Widmer's algorithm presented the smallest difference compared to the CT. Misinterpretation of postoperative planar radiographs is a common problem in THA. CONCLUSION: Planar radiographs are too imprecise for exact evaluation of the correct cup AV after THA. CT-based analysis may be necessary if exact values are required.
INTRODUCTION: Anteroposterior pelvic radiographs are routinely used to monitor cup orientation in total hip arthroplasty (THA). Analysis of planar radiographs leads to a certain degree of measurement error for the cup anteversion (AV). With the current study, we wanted to clarify whether planar radiography can be used for accurate evaluation of the THA position. MATERIALS AND METHODS: The postoperative orientation of pelvic implants in 42 patients was analyzed according to five documented mathematical algorithms using planar radiographs. Postoperative computed tomography (CT) pelvis scans were available for all patients. A CT-based navigation system was used to determine AV. RESULTS: The comparison showed that all five formulas presented substantial variations for the AV angle. Of these, Widmer's algorithm presented the smallest difference compared to the CT. Misinterpretation of postoperative planar radiographs is a common problem in THA. CONCLUSION: Planar radiographs are too imprecise for exact evaluation of the correct cup AV after THA. CT-based analysis may be necessary if exact values are required.
Authors: T Schwarz; M Weber; M Wörner; T Renkawitz; J Grifka; B Craiovan Journal: Int J Comput Assist Radiol Surg Date: 2016-10-06 Impact factor: 2.924
Authors: Bernard Ghelman; Christopher K Kepler; Stephen Lyman; Alejandro González Della Valle Journal: Clin Orthop Relat Res Date: 2009-03-10 Impact factor: 4.176
Authors: Johannes Beckmann; Dirk Stengel; Markus Tingart; Jürgen Götz; Joachim Grifka; Christian Lüring Journal: Acta Orthop Date: 2009-10 Impact factor: 3.717