model-based radiostereometric analysis (RSA) randomized control trial evaluating the stability of the cementless Taperloc hip stem: the TapHip study
Acta Orthopaedica, vol. 93, pp. 212–221
Abstract
Background and purpose - The Taperloc Complete hip is the successor of the Taperloc hip, aiming to increase range of motion and optimizing femoral fit with intermediate stem sizes. We evaluated whether these design changes affect fixation, and this RSA study compares 2-year migration. Patients and methods - In this prospective, multi-arm study, 100 patients were randomized to cementless total hip arthroplasty (THA) with Taperloc Complete full profile (TCFP), Taperloc Complete reduced distal (TCRD), Taperloc full profile (TFP), or Taperloc reduced distal (TRD). Migration was measured with model-based RSA postoperatively, and after 3, 12, and 24 months. Results - Results based on mixed-model analysis on 2-year postoperative RSA data from 74 patients showed similar subsidence (mm) in the first 3 months (mean [95% CI] TCFP 0.44 [0.20-0.69], TCRD 0.91 [0.40-1.42], TFP 0.71 [0.22-1.19], TRD 1.25 [0.58-1.91]) and stabilization afterwards. The TCFP showed statistically significantly less retroversion (°) at 2-year postoperatively compared with TFP and TCRD (mean [95% CI] TCFP: -0.13 [-0.64 to 0.38], TCRD: 0.84 [0.35-1.33], TFP: 0.56 [0.12-1.00], TRD: 0.37 [-0.35 to 1.09]). Interpretation - As expected in successful cementless THA, RSA shows stabilization after initial subsidence. Based on these results the Taperloc Complete stem is expected to have similar long-term fixation to the Taperloc stems. The reduced distal groups have larger, but statistically non-significant, initial migration compared with the TCFP group, which could be due to implantation in Dorr B, C femur types. It may be important to consider the femur shape for choosing a full profile or reduced distal stem to minimize migration.
Authors 5
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Leiden University Medical Center · Medisch Centrum Haaglanden · Stichting Haaglanden Medisch Centrum
Affiliation as printed
Focuskliniek Orthopedie, Haaglanden Medical Center, the Hague; Department of Orthopaedics, Leiden University Medical Center, Leiden. Kokruben@gmail.com
Department of Orthopaedics, Leiden University Medical Center, Leiden
Focuskliniek Orthopedie, Haaglanden Medical Center, the Hague
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Leiden University Medical Center
Affiliation as printed
Department of Orthopaedics, Leiden University Medical Center, Leiden. L.A.Koster@lumc.nl
Department of Orthopaedics, Leiden University Medical Center, Leiden
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Leiden University Medical Center
Affiliation as printed
Department of Orthopaedics, Leiden University Medical Center, Leiden. b.l.kaptein@lumc.nl
Department of Orthopaedics, Leiden University Medical Center, Leiden
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Leiden University · Leiden University Medical Center
Affiliation as printed
Department of Medical Statistics and Bioinformatics, Leiden University Medical Center, Leiden; Mathematical Institute, Leiden University, Leiden, The Netherlands. m.fiocco@math.leidenuniv.nl
Department of Medical Statistics and Bioinformatics, Leiden University Medical Center, Leiden
Mathematical Institute, Leiden University, Leiden, The Netherlands
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Medisch Centrum Haaglanden · Stichting Haaglanden Medisch Centrum
Affiliation as printed
Focuskliniek Orthopedie, Haaglanden Medical Center, the Hague. s.keizer@haaglandenmc.nl
Focuskliniek Orthopedie, Haaglanden Medical Center, the Hague
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