Prospective comparative analysis from pre- to postoperative changes in Single Assessment Numeric Evaluation (SANE) for patellofemoral instability.

Purpose: Single Assessment Numeric Evaluation (SANE) has been introduced for the pre-operative assessment of lateral patellar instability (LPI), but post-operative evaluation is lacking. This study aimed to investigate the ability of SANE questions (SQs) to assess patients with LPI before and after surgery. Methods: 120 consecutive patients with LPIs were prospectively assessed via the Banff Patella Instability Instrument 2.0 (BPII 2.0). Patients were randomised into three groups (40 each) and asked to answer 1 of 3 SQs: "How do you rate your knee joint if a completely stable kneecap means 100%?" (SQ1), "How do you rate your knee joint if complete satisfaction means 100%?" (SQ2), "How do you rate your knee joint if complete normal function means 100%?" (SQ3). At ≥24 months post-operatively, 98 patients (81.6%) underwent reassessment with previous SQs and BPII 2.0. Results: Post-operatively, the average BPII 2.0 was 77.7 ± 17.3 points. Mean SQ1, SQ2 and SQ3 results euqalled BPII 2.0 values and were 82.9%, 77.1% and 80.1%, respectively, without differences between groups (all Conclusion: All three SANE questions reflected significant post-operative improvement consistent with BPII 2.0 outcomes. However, correlations varied from pre- to post-operative. While SQ1 previously demonstrated concurrent validity with BPII 2.0 pre-operatively, SQ3 exhibited the strongest correlation with BPII 2.0 post-operatively, warranting cautious interpretation given study limitations. Level of Evidence: Level II.