Intra- and inter-observer agreement in MRI assessment of rotator cuff healing using the Sugaya classification 10 years after surgery

Background The long-term outcomes of rotator cuff repair are unclear. Recurrent tears are common, although their reported frequency varies depending on the type and interpretation challenges of the imaging method used. The primary objective of this study was to assess the intra- and inter-observer reproducibility of the MRI assessment of rotator cuff repair using the Sugaya classification 10 years after surgery. The secondary objective was to determine whether poor reproducibility, if found, could be improved by using a simplified yet clinically relevant classification. Hypothesis Our hypothesis was that reproducibility was limited but could be improved by simplifying the classification. Material and method In a retrospective study, we assessed intra- and inter-observer agreement in interpreting 49 magnetic resonance imaging (MRI) scans performed 10 years after rotator cuff repair. These 49 scans were taken at random among 609 cases that underwent re-evaluation, with imaging, for the 2015 SoFCOT symposium on 10-year and 20-year clinical and anatomical outcomes of rotator cuff repair for full-thickness tears. Each of three observers read each of the 49 scans on two separate occasions. At each reading, they assessed the supra-spinatus tendon according to the Sugaya classification in five types. Results Intra-observer agreement for the Sugaya type was substantial (κ = 0.64) but inter-observer agreement was only fair (κ = 0.39). Agreement improved when the five Sugaya types were collapsed into two categories (1–2–3 and 4–5) (intra-observer κ = 0.74 and inter-observer κ = 0.68). Conclusion Using the Sugaya classification to assess post-operative rotator cuff healing was associated with substantial intra-observer and fair inter-observer agreement. A simpler classification into two categories improved agreement while remaining clinically relevant. Level of evidence II, prospective randomised low-power study.