[Mid-term results of cementless ultima cups in primary total hip replacement].

PURPOSE OF THE STUDY To present the results of primary total hip arthroplasty (THA) with use of the hemispheric threaded Ultima cup at 8.5-year follow-up. MATERIAL Between 1996 and 1999, a total of 40 Ultima acetabular components were used in 33 patients (15 men and 18 women). The average age at the time of surgery was 61.2 years (range, 45 to 71). By the end of 2006, 36 cups were assessed. Indications for the primary THA procedure included primary arthritis in 32 hips, post-traumatic arthritis in three, post-dysplastic arthritis in two, femoral neck fracture in two and rheumatoid arthritis in one. METHODS The average follow-up was 8.5 years (range, 7 to 10). The indication criteria for primary implantation were evaluated, i.e., body mass index, patients' activity and their age. THA outcome was evaluated on the basis of clinical rating (Harris hip score) and pain assessment and on radiographic findings on which the acetabulum before and cup position after THA were compared, and potential changes in cup position, acetabular cup loosening or para-articular ossifications were observed. RESULTS Good outcomes were found in 88.9 % of the hips. In most, cup position was satisfactory. One acetabular component was implanted in a varus position (34 degrees ). An intraoperative complication included fracture of the greater trochanter, which was left untreated for spontaneous healing. The early-postoperative complications were one dislocation, two wounds with serous secretion not requiring revision surgery, and one large haematoma. Stem fracture as a late complication was recorded in two THAs. Radiolucencies were found in six hips and paraarticular ossifications in four. Migration of the cup with protrusion into the acetbulum occurred in one patient 3 years after THA. Four cups showed aseptic loosening within 3 to 7 years of surgery. No infection was recorded in this THA group. DISCUSSION Information on mid- and long-term outcomes of the use of cementless acetabular cups in the relevant literature is sparse. The Ultima cup is dealt with only in the report by Pazdírek et al., whose results are in agreement with ours, but involve a lower number of implanted cups and a shorter follow-up. In this study, loosening was recorded only in cups larger than 32 mm in diameter. In comparison with our group of cementless BMT acetabular components, the use of cementless Ultima cups gives better results at mid-term follow-up. CONCLUSIONS At 8.5-year follow-up, 88.9 % of the Ultima acetabular components were without radiographic signs of loosening. Attention should be paid primarily to THA patients with a thin wall acetabulum requiring a larger cup and a 32-mm liner.