Forgotten Shoulder ASAP-22: a scapula-inclusive shoulder ecosystem PROM-Pilot study in reverse total shoulder arthroplasty and related pathologies.

Background: Reverse total shoulder arthroplasty (rTSA) is now the most commonly performed type of shoulder arthroplasty. However, most legacy patient-reported outcome measures (PROMs) were developed before the widespread adoption of rTSA and often fail to address its unique challenges-particularly those related to altered scapular mechanics, rotational limitations, and instability. The Forgotten Shoulder Adaptive Scapula Analytics and Performance Score (FS ASAP-22) was developed to fill these gaps, utilizing an adaptive scoring model grounded in the "forgotten joint" concept. To our knowledge, it is the first PROM to include a dedicated domain for posture and scapular mechanics. We hypothesized that the FS ASAP-22 would show strong correlations with established PROMs while minimizing ceiling effects and providing enhanced granularity and clinical relevance. Methods: In this pilot study, 30 patients with shoulder conditions relevant to rTSA completed the FS ASAP-22, American Shoulder and Elbow Surgeons (ASES) score, and Subjective Shoulder Value (SSV). The FS ASAP-22 includes 22 items across 10 domains covering pain, night pain, internal rotation, external rotation, overhead reach, range of motion (stiffness), strength, function, instability, and scapula assessment. We assessed internal consistency (Cronbach's alpha), construct validity (Spearman's correlation), and missing data. An adaptive scoring system was used for tasks that could not be performed due to reasons unrelated to the shoulder. Results: The mean FS ASAP-22 score was 69 ± 13 (range 20-94), compared to ASES (72 ± 16) and SSV (69 ± 19). The FS ASAP-22 showed no ceiling effect and a lower median score (65), with no clustering among high-functioning patients. Internal consistency was high across most domains (α = 0.84-0.94), and construct validity was strong, with correlations to ASES (ρ = 0.82) and SSV (ρ = 0.84). Domains addressing rotation and scapular mechanics provided unique insights into active rotation in space, patient posture, and scapular pain distribution. These aspects are not captured by legacy scores. The instability domain showed poor internal consistency, likely due to low symptom prevalence. Only 2.6% of responses were missing (17 of 660), supporting the feasibility of the adaptive forma. Conclusion: The FS ASAP-22 demonstrates strong initial construct validity and high consistency of most domains. Its domain-specific, adaptive structure addresses key limitations of traditional PROMs. Strong correlations with ASES and SSV support backward compatibility with historical data, while the inclusion of novel domains may enhance longitudinal tracking and patient care. Further validation in larger and disease-specific cohorts is warranted.