Comparison of a Single Assessment Numeric Evaluation Method and the Banff Patella Instability Instrument 2.0 for Patients With Patellofemoral Instability.

BACKGROUND

The concept of Single Assessment Numeric Evaluation (SANE) has been introduced for several clinical entities; however, a validated SANE focusing on patients with patellofemoral instability has not been described.

PURPOSE/HYPOTHESIS: The purpose of this study was to investigate the expressiveness of SANE questions (SQs) for the assessment of patients experiencing patellofemoral instability. It was hypothesized that the complexity of patellofemoral instability cannot be demonstrated by a single question.

STUDY DESIGN

Cohort study (diagnosis); Level of evidence, 2.

METHODS

Between October 2022 and March 2023, 120 consecutive patients (male/female, 50/70; mean age, 23.9 ± 8.0 years; mean body mass index, 25.3 ± 5.1 kg/m) with patellofemoral instability were assessed with the Banff Patella Instability Instrument 2.0 (BPII 2.0). Patients were randomized into 3 groups (40 patients each) and asked to answer 1 of 3 SQs: "How do you rate your knee joint if a completely stable kneecap means 100%?" (SQ 1), "How do you rate your knee joint if complete satisfaction means 100%?" (SQ 2), and "How do you rate your knee joint if complete normal function means 100%?" (SQ 3). Means ± standard deviations were compared using 1-way analysis of variance, the correlation between BPII 2.0 and each SQ was assessed by Pearson correlation, and Bland-Altmann analysis was performed to investigate biases of each SQ in comparison with BPII 2.0.

RESULTS

The mean BPII 2.0 score was 40.5 ± 16.8 points, and the mean results of SQ 1, SQ 2, and SQ 3 were 44.2% ± 26.0%, 42.6% ± 25.4%, and 44.2% ± 18.9%, respectively, without significant differences between the groups (all > .05). The correlations between BPII 2.0 and SQ 1, SQ 2, and SQ 3 were high ( = 0.75; 95% CI, 0.58 to 0.86; < .0001), low ( = 0.35; 95% CI, -0.05 to 0.6; = .02), and low ( = 0.31; 95% CI, -0.002 to 0.56; = .051), respectively. Bland-Altman analysis between BPII 2.0 and SQ 1, SQ 2, and SQ 3 revealed biases of -0.12 (SD, 17.1), -1.45 (SD, 24.4), and -8.0 (SD, 19.4), respectively.

CONCLUSION

The SQ "How do you rate your knee joint if a completely stable kneecap means 100%?" demonstrated concurrent validity with the BPII 2.0 and may serve as a helpful tool to quickly assess patients with recurrent patellofemoral instability in a preoperative setting.