The Wear Rate of Highly Cross-Linked Polyethylene in Total Hip Replacement Is Not Increased by Large Articulations: A Randomized Controlled Trial.
BACKGROUND
Larger articulations reduce the risk of dislocation following primary total hip arthroplasty, leading to increased use of these articulations. The wear rate of highly cross-linked polyethylene (XLPE) is low in standard-diameter articulations but remains unclear in larger articulations. The aim of this randomized controlled trial was to compare the mean wear rates of 36-mm and 28-mm metal-on-XLPE articulations between 1 and 3 years postoperatively.


METHODS
Fifty-six elderly patients undergoing primary total hip arthroplasty were randomized intraoperatively to receive either a 36-mm or 28-mm metal-on-XLPE articulation. Factors that may affect wear were controlled by study design. Wear was measured using radiostereometric analysis.


RESULTS
Mean annual proximal wear rates between 1 and 3 years were 0.00 and 0.01 mm/yr for the 36 and 28-mm articulation cohorts, respectively. No patient had a proximal wear rate of >0.1 mm/yr. Mean wear was very low in all directions, and the wear rate of 36-mm articulations was not significantly greater than that of 28-mm articulations on the basis of proximal, medial 2-dimensional, and 3-dimensional wear.


CONCLUSIONS
The wear rate of a larger 36-mm metal-on-XLPE articulation between 1 and 3 years following primary total hip arthroplasty was low and no greater than that of a 28-mm articulation. However, before a 36-mm metal-on-XLPE articulation is widely recommended, particularly in young active patients, long-term wear rates and association between wear and periprosthetic osteolysis should be determined.


METHODS
Therapeutic Level II. See Instructions for Authors for a complete description of levels of evidence.
Department of Orthopaedics and Trauma, Royal Adelaide Hospital, Adelaide, SA, Australia.
Donald W
DW
Howie
Department of Orthopaedics and Trauma, Royal Adelaide Hospital, Adelaide, SA, Australia.
Oksana T
OT
Holubowycz
Department of Orthopaedics and Trauma, Royal Adelaide Hospital, Adelaide, SA, Australia.
Stuart A
SA
Callary
D000368:Aged; D019644:Arthroplasty, Replacement, Hip; D005260:Female; D006621:Hip Joint / Q000601:surgery; D006622:Hip Prosthesis; D006801:Humans; D008297:Male; D015207:Osteoarthritis, Hip / Q000601:surgery*; D020959:Polyethylene; D011474:Prosthesis Design; D011475:Prosthesis Failure; D013314:Stress, Mechanical; D016896:Treatment Outcome
D020959:Polyethylene