Paper 59: Anchor-based thresholds may better define meaningful 6-month recovery than distribution methods following jones fracture open reduction and internal fixation

Objectives: Operative fixation of Jones fractures is common in active patients, yet thresholds for meaningful functional recovery remain poorly defined. The goal of minimal clinically important differences (MCIDs) is to establish universal benchmarks for patient-reported outcome measures [1]. However, different methods for calculating MCID can yield widely varying thresholds [1]. This study aimed to determine which method of MCID calculation better identified meaningful recovery at 6 months following open reduction and internal fixation (ORIF) for Jones fractures: anchor-based thresholds (derived from sensitivity and specificity analyses) or distribution-based thresholds (such as one-half standard deviation, ½SD). We hypothesized that anchor-based methods would more accurately capture clinically meaningful recovery than traditional distribution-based approaches.
Methods: We retrospectively reviewed, under IRB approval, patients who underwent ORIF with a partially threaded cancellous screw for fifth metatarsal Jones fractures between 2015-2023. Patient-reported outcomes included FAAM-ADL, FAAM-Sport, and VAS pain scores at baseline at approximately 6 months. Anchor-based thresholds (Sensitivity- and specificity-based derivations) were derived using receiver operating characteristic (ROC) analyses with a PASS anchor question ('Are your current symptoms acceptable?' yes/no). MCID was defined as the change score that best discriminated between PASS and non-PASS responders, while PASS thresholds were defined as absolute scores that best discriminated between PASS and non-PASS responders. Thresholds were selected via Youden's J statistic and reported with AUC, sensitivity, and specificity. Distribution-based MCIDs were calculated as ½SD of baseline scores.
Results: A total of 30 patients with available FAAM-ADL scores were included (mean age 23.8 +- 9.9 years, 73.3% male, BMI 26.2 +- 3.8). At approximately 6 months postoperatively, the anchor-based MCID for FAAM-ADL was 59.52 points (AUC 0.622, sensitivity 0.82, specificity 0.50), while the PASS threshold was 92.50 points (AUC 0.773, sensitivity 0.91, specificity 0.62). In contrast, the distribution-based MCID was substantially lower at 12.26 points.Among 23 patients with FAAM-Sport data (mean age 21.1 +- 8.1 years, 82.6% male, BMI 25.8 +- 3.8), the anchor-based MCID was 56.25 points (AUC 0.781, sensitivity 0.88, specificity 0.71), and the PASS threshold was 78.13 points (AUC 0.821, sensitivity 0.94, specificity 0.71). The distribution-based MCID was only 7.91 points.For VAS pain scores, data were available for 29 patients (mean age 24.0 +- 10.1 years, 72.4% male, BMI 26.2 +- 3.8). The anchor-based MCID was -6.00 points (AUC 0.390, sensitivity 0.33, specificity 0.75), and the PASS threshold was 0.00 points (AUC 0.179, sensitivity 0.00, specificity 1.00), indicating poor discriminatory performance. The distribution-based MCID for VAS pain was 1.45 points.
Conclusions: Anchor-based thresholds yield substantially higher and more patient-relevant recovery benchmarks at 6 months following Jones fracture ORIF compared to conventional ½SD estimates. Functional outcomes (FAAM-ADL, FAAM-Sport) demonstrated strong discrimination for PASS, whereas VAS pain did not. Results of this study are limited by the small sample size and require validation with larger cohorts. Nonetheless, these anchor-based thresholds provide preliminary actionable clinical targets for patient counseling, and postoperative rehabilitation in the short term.