Advertisement for orthosearch.org.uk
Results 1 - 1 of 1
Results per page:
Applied filters
Hip

Include Proceedings
Dates
Year From

Year To
Orthopaedic Proceedings
Vol. 100-B, Issue SUPP_13 | Pages 41 - 41
1 Oct 2018
Tatka J Brady AW Matta JM
Full Access

Introduction

Accurate acetabular position is an important goal during THA. It is also well known that accurate acetabular positioning is very frequently not achieved, even by experienced, high volume surgeons. Problems associated with cup malposition are: dislocation, accelerated poly wear, impingement, ceramic squeaking, metalosis. Murray et al described 3 methods of measurement and assessment of acetabular inclination and anteversion (I&A): anatomic, radiographic and operative. It is the hypothesis of the authors, that the differences and details of these 3 methods are poorly understood by many surgeons and this is contributory to inconsistent cup positioning. Additionally, the radiographic method, which is most commonly used for post op assessment and academic studies, contributes to misunderstanding and error. Modern computer guidance and software assessment of radiographs allows us to easily measure anatomic I&A which should be thought of as “true” I&A.

Methods

The mathematical criteria for radiographic measurement of anatomic I&A are defined as well as the mathematical relationships and discrepancies between anatomic and radiographic I&A for any given cup.

A = A n g l e o f a n t e v e r s i o n o f c u p I = A n g l e o f i n c l i n a t i o n o f c u p

E = Angle of ellipse major diameter to horizontal

E = Radiographic inclination

Sin A = H o r i z o n t a l w i d t h o f e l l i p s e L e n g t h o f e l l i p s e m a j o r d i a m e t e r Sin I = V e r t i c a l h e i g h t o f e l l i p s e L e n g t h o f e l l i p s e m a j o r d i a m e t e r

Tan I = Tan E / Cos A

Tan E = (Tan I) x (Cos A)