The Effect On Polyethylene Wear Of Different Femoral Heads In Cases Of Uncemented Total Hip Arthroplasty

OBJECTIVES. Alternative joint surfaces have been developed to reduce the problem of PE wear causing periprosthetic osteolysis and aseptic loosening following Total Hip Arthroplasty (THA). This study examined differences in the amount of PE wear with the use of metal or ceramic heads. METHODS. The study comprised 92 hips with uncemented THA of the same prosthesis type (BICONTACT-Aesculap, Tutlingen) with a minimum 5-year follow-up. Conventional PE was used in all cases. All femoral heads were 28 mm in diameter and ceramic (Group I) in 69 hips (75%) and cobalt-chrome alloy (Group II) in 23 hips (25%). The two groups were of similar age, sex ratio, activity level, body mass index and follow-up period. The location of the acetabular component was determined according to the Ranawat method. The Dorr method was used to measure linear wear in the polyethylene. RESULTS. The Harris hip score rose from average 52 (35-65) to 89 (76-98) in Group I and in Group II from 45 (26-59) to 87 (79-97) (p > 0.05). The annual PE wear was an average of 0.16 mm (0.006-0.44) in Group I and in Group II 0.25 mm (0.08-0.48) the difference being statistically significant (p=0.001). In Group I, the location of the acetabular component was in place in 53 hips (76.8%), above (5-9 mm) in 11 hips (15.9%), and lower (5-8 mm) in 5 hips (7.3%). In Group II, these values were 17 (73.9%), 4 (17.3%) (5-8 mm), and 2 (8.8%) (5-9 mm) respectively. The acetabular index was average 43 deg (40 deg -48 deg ) in Group I and 41 deg (39 deg -47 deg ) in Group II (p > 0.05). CONCLUSIONS. We conclude that although there is no difference between the groups with THA from the clinical results aspect, the annual amount of PE wear is less in cases where a ceramic femoral head is used and therefore this should be preferred.