Background and purpose — Standardized reporting on methodology and results in clinical RSA research papers facilitates evaluation of quality and interpretation of results. We aimed to assess the extent to which radiostereometric analysis (RSA) and computed tomography-based RSA (CT-RSA) studies adhered to the items of the new RSA reporting guideline from 2024. Methods — A systematic literature search was performed to identify all clinical RSA studies published between January 2012 and February 2024. Studies were eligible for inclu-sion if prosthesis migration over time was assessed. The adherence of studies to each applicable guideline item (full, partial, or no) was assessed. Results — 285 studies were included, most of which assessed prosthesis migration in the hip (n = 161) or knee (n = 99). No study reported on all guideline items. The mean (full or partial) adherence of studies to all (appli-cable) items was 61% (standard deviation [SD] 11). Large variation between the reporting of items was found, ranging from being reported in 1% of the studies to 100%. The least reported items in studies were the mean number and SD of days between surgery and baseline RSA examination (8% of studies), mean number and SD of days between surgery and primary endpoint RSA examination (1%), and consistent-or all-marker method for RSA analysis (3%). Conclusion — Current studies on average reported only 61% of the items from the updated RSA guidelines. Adherence to the guidelines in clinical RSA studies on prosthesis migration should be improved, in order to improve the quality of studies and the interpretation of outcomes on implant migration.

Aims The objective of this study was to compare the two-year migration and clinical outcomes of a new cementless hydroxyapatite (HA)-coated titanium acetabular shell with its previous version, which shared the same geometrical design but a different manufacturing process for applying the titanium surface. Methods Overall, 87 patients undergoing total hip arthroplasty (THA) were randomized to either a Trident II HA or Trident HA shell, each cementless with clusterholes and HA-coating. All components were used in combination with a cemented Exeter V40 femoral stem. Implant migration was measured using radiostereometric analysis (RSA), with radiographs taken within two days of surgery (baseline), and at three, 12, and 24 months postoperatively. Proximal acetabular component migration was the primary outcome measure. Clinical scores and patient-reported outcome measures (PROMs) were collected at each follow-up. Results Mean proximal migrations at three, 12, and 24 months were 0.08 mm (95% confidence interval (CI) 0.03 to 0.14), 0.11 mm (95% CI 0.06 to 0.16), and 0.14 mm (95% CI 0.09 to 0.20), respectively, in the Trident II HA group, versus 0.11 mm (95% CI 0.06 to 0.16), 0.12 mm (95% CI 0.07 to 0.17), and 0.14 mm (95% CI 0.09 to 0.19) in the Trident HA group (p = 0.875). No significant differences in translations or rotations between the two designs were found in any other direction. Clinical scores and PROMs were comparable between groups, except for an initially greater postoperative improvement in Hip disability and Osteoarthritis Outcome Symptoms score in the Trident HA group (p = 0.033). Conclusion The Trident II clusterhole HA shell has comparable migration with its predecessor, the Trident hemispherical HA cluster shell, suggesting a similar risk of long-term aseptic loosening. Cite this article: Bone Joint J 2024;106-B(2):136–143.