Mid-term migration of a cementless, porous acetabular cup; A 5 year Radiostereometric Analysis

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Nilsson, Kjell G
Theodoulou, Annika
Mercer, Graham
Quinn, Stephen John
Krishnan, Jeganath
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© 2017 Elsevier.
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Purpose The aim of the study was to determine the 5 year migratory and wear patterns, adverse events and clinical outcomes of a cementless, porous acetabular cup. Methods RSA imaging of a cohort of 11 patients was retrospective analysed at 5 years post Total Hip Arthroplasty (THA). Changes in pain, function and symptoms of the hip at 5 years post-THA were compared to preoperative and 2 year postoperative assessments on the Harris Hip Score (HHS) and Hip dysfunction and Osteoarthritis Outcome Score (HOOS). Results The majority of cup migration occurred up to 6 months and stabilised thereafter (6 months to 5 years, p = 0.091–0.866, Wilcoxon Signed Rank test). The direction of rotation around the 3 axes was evenly distributed among the cups between anterior-posterior rotation, internal-external rotation and increased-decreased inclination. The majority of the cups translated proximally, at an average migration of 0.36 mm (±95%CI 0.17) at 5-years post-THA. Following initial bedding in, up to 6 months, there was no detectable polyethylene wear between 6 months and 5 years. At 5 years postoperatively, a statistically significant difference was observed across all HOOS subscales in comparison to preoperative values, with higher means reported at 5 years (p < 0.001). The total mean HHS displayed a statistically significant improvement, increasing from ‘poor’ preoperatively to ‘good’ at 5 years post-THA. Conclusion Following initial migration between discharge and 6 months, the cementless porous acetabular cup demonstrated a tendency for stabilisation from 6 months up to 5 years post-THA, suggesting good mid-term fixation. Additionally, improvements in clinical outcome measures of pain, function and quality-of-life remained high following THA at 5 years post-surgery.
© 2017 Elsevier. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/ This author accepted manuscript is made available following 12 month embargo from date of publication (July 2017) in accordance with the publisher’s archiving policy
Acetabular Cup, Migration, Radiostereometric Analysis, RSA, Total Hip Arthroplasty, THA
Nilsson, Kjell G., et al. "Mid-term migration of a cementless, porous acetabular cup; A 5year Radiostereometric Analysis." Journal of Orthopaedics (2017).