A model-based radiostereometric analysis (RSA) randomized control trial evaluating the stability of the cementless Taperloc hip stem: the TapHip study

2-year follow-up RSA and PROMs results

Authors

  • Ruben Y Kok Focuskliniek Orthopedie, Haaglanden Medical Center, the Hague; Department of Orthopaedics, Leiden University Medical Center, Leiden
  • Lennard A Koster Department of Orthopaedics, Leiden University Medical Center, Leiden https://orcid.org/0000-0002-5874-389X
  • Bart L Kaptein Department of Orthopaedics, Leiden University Medical Center, Leiden https://orcid.org/0000-0001-8772-9985
  • Marta Fiocco Department of Medical Statistics and Bioinformatics, Leiden University Medical Center, Leiden; Mathematical Institute, Leiden University, Leiden, The Netherlands
  • Stefan B Keizer Focuskliniek Orthopedie, Haaglanden Medical Center, the Hague https://orcid.org/0000-0002-5975-4590

DOI:

https://doi.org/10.2340/17453674.2021.1127

Keywords:

Arthroplasty, Hip, Implants, Osteoarthrosis, RCT, Roentgen stereophotogrammetric analysis, total hip arthroplasty

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.

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Published

2022-01-03

How to Cite

Kok, R. Y., Koster, L. A., Kaptein, B. L., Fiocco, M., & Keizer, S. B. (2022). A model-based radiostereometric analysis (RSA) randomized control trial evaluating the stability of the cementless Taperloc hip stem: the TapHip study: 2-year follow-up RSA and PROMs results. Acta Orthopaedica, 93, 212–221. https://doi.org/10.2340/17453674.2021.1127

Issue

Section

Randomized clinical trial