Metal-on-polyethylene versus metal-on-metal bearing surfaces in total hip arthroplasty: a prospective randomised study investigating metal ion levels and chromosomal aberrations in peripheral lymphocytes.
The long term biological effects of wear products following total hip arthroplasty (THA) are unclear. However, the indications for THA are expanding, with increasingly younger patients undergoing the procedure. This prospective, randomised study compared two groups of patients undergoing THA after being randomised to receive one of two different bearing surfaces: metal-on-polyethylene (MoP) n = 22 and metal-on-metal (MoM) n = 23. We investigated the relationship between three variables: bearing surface (MoP vs MoM), whole blood levels of chromium (Cr) and cobalt (Co) and chromosomal aberrations in peripheral lymphocyte pre-operatively and at one, two and five years post-surgery. Our results demonstrated significantly higher mean cobalt and chromium (Co and Cr) blood levels in the MoM group at all follow-up points following surgery (p < 0.01), but there were no significant differences in the chromosomal aberration indices between MoM and MoP at two or five years (two years: p = 0.56, p = 0.08, p = 0.91, p = 0.51 and five years: p = 0.086, p = 0.73, p = 0.06, p = 0.34) for translocations, breaks, loss and gain of chromosomes respectively. Regression analysis showed a strong linear relationship between Cr levels and the total chromosomal aberration indices in the MoM group (R(2) = 0.90016), but this was not as strong for Co (R(2) = 0.68991). In the MoP group, the analysis revealed a poor relationship between Cr levels and the total chromosomal aberration indices (R(2) = 0.23908) but a slightly stronger relationship for Co (R(2) = 0.64292). Across both groups, Spearman's correlation detected no overall association between Co and Cr levels and each of the studied chromosomal aberrations. There remains no clear indication which THA bearing couple is the most biocompatible, especially in young active patients. While THA continues to be very successful at alleviating pain and restoring function, the long-term biological implications of the procedure still require further scrutiny.
Royal National Orthopaedic Hospital, Brockley Hill, Stanmore, Middlesex, HA7 4LP, UK.
T W R
TW
Briggs
Joint Replacement Institute, University of Western Ontario, London, Ontario, N6G 2V4, Canada.
S A
SA
Hanna
Royal National Orthopaedic Hospital, Brockley Hill, Stanmore, Middlesex, HA7 4LP, UK.
B
B
Kayani
East and North Hertfordshire NHS Trust, Coreys Mill Lane, Stevenage, SG1 4AB, UK.
S
S
Tai
Royal National Orthopaedic Hospital, Brockley Hill, Stanmore, Middlesex, HA7 4LP, UK.
R C
RC
Pollock
Royal National Orthopaedic Hospital, Brockley Hill, Stanmore, Middlesex, HA7 4LP, UK.
S R
SR
Cannon
Institute of Orthopaedics and Musculoskeletal Science, Royal National Orthopaedic Hospital, Brockley Hill, Stanmore, Middlesex, HA7 4LP, UK.
G W
GW
Blunn
Royal National Orthopaedic Hospital, Brockley Hill, Stanmore, Middlesex, HA7 4LP, UK.
R W J
RW
Carrington
D000368:Aged; D000369:Aged, 80 and over; D019644:Arthroplasty, Replacement, Hip / Q000009:adverse effects / Q000295:instrumentation*; D002857:Chromium / Q000097:blood* / Q000494:pharmacology; D002869:Chromosome Aberrations; D003035:Cobalt / Q000097:blood* / Q000494:pharmacology; D005260:Female; D006622:Hip Prosthesis / Q000009:adverse effects*; D006801:Humans; D008214:Lymphocytes / Q000187:drug effects; D008297:Male; D061825:Metal-on-Metal Joint Prostheses / Q000009:adverse effects*; D008875:Middle Aged; D020959:Polyethylene; D011184:Postoperative Period; D011474:Prosthesis Design
D002857:Chromium; D003035:Cobalt; D020959:Polyethylene
Chromosomes; Hip; Ions; Metal; Polyethylene; Replacement