Hemispheric cups do not reproduce acetabular rim morphology.
BACKGROUND
Iliopsoas impingement is a recurrent complication following THA, caused by muscle friction against a protrusive prosthetic cup.This study was designed to quantify the dimensional variations in acetabular rim profiles, with particular regard to the iliopubic valley, in order to suggest means to prevent iliopsoas impingement.


METHODS
34 cadaver pelvises were analyzed using a hip navigation system. The morphometric data were processed to plot profiles of all acetabular rims with particular regard to the shape and depth of the psoas valley.


RESULTS
The acetabular rim is an asymmetric succession of 3 peaks and 3 troughs. The psoas valley is a salient feature in most pelvises and there is only a weak correlation between its depth (mean 3.8 mm, SD 2.0) and acetabular diameter, anteversion, or inclination.


CONCLUSIONS
It would be difficult to obviate the anterior overlap of the acetabulum using a hemispheric cup, a fortiori in certain morphotypes, without compromising range of motion or risk of dislocation. The solution for prevention of iliopsoas impingement would be to adapt cup design to acetabular anatomy, which may require different implants for the right and left sides, and hence a doubled inventory.
Vandenbussche
Eric
E
Department of Orthopaedic Surgery, Hôpital Européen Georges Pompidou, 20 Rue Leblanc, FR-75908 Paris, France. eric.vdb@egp.ap-hop-paris.fr
Saffarini
Mohammed
M
Delogé
Nicolas
N
Moctezuma
José-Luis
JL
Nogler
Michael
M
D000077:Acetabulum / Q000033:anatomy & histology / Q000601:surgery*; D000368:Aged; D000369:Aged, 80 and over; D019644:Arthroplasty, Replacement, Hip / Q000009:adverse effects / Q000295:instrumentation; D002102:Cadaver; D020099:Coated Materials, Biocompatible; D005260:Female; D006622:Hip Prosthesis; D006801:Humans; D008297:Male; D008875:Middle Aged; D010149:Postoperative Pain / Q000209:etiology / Q000517:prevention & control; D011474:Prosthesis Design; D011475:Prosthesis Failure; D016658:Psoas Muscles; D012086:Reoperation
D020099:Coated Materials, Biocompatible