Augmented Broström Enables Patients with Anatomic Ankle Deformities to Achieve Population Mean Function and Pain as Measured by PROMIS

Research Type: Level 3 - Retrospective cohort study, Case-control study, Meta-analysis of Level 3 studies Introduction/Purpose: The extent to which primary Broström with InternalBraceTM augmentation enables patients with deformities to achieve satisfactory patient-reported outcomes is unclear. Patient Reported Outcomes Measurement Information System (PROMIS) computerized adaptive tests (CATs) of physical function (PF) and pain interference (PI) are a validated metric of orthopaedic foot and ankle clinical outcomes, and the Cumberland Ankle Instability Tool (CAIT) is a validated metric of ankle stability. This study aimed to determine a) whether patients with deformities have worse outcomes than patients who undergo Broström for other ankle instability etiologies and b) whether augmentation results in better PROMIS and CAIT scores for patients with deformities compared to non-augmented Broström. We hypothesized that InternalBrace augmentation would improve PROMIS and CAIT scores for patients with deformities compared to primary Broström. Methods: 574 patients who underwent lateral ankle ligament reconstruction at a single institution between 2013-2024 were retrospectively reviewed. Two investigators independently evaluated all records. Revisions, Evans procedures, allografts, nonanatomic reconstructions, flexor digitorum longus transfers, pes planus deformities, concomitant tibiotalar arthrodesis, associated ankle arthroplasties, and concomitant fractures or nonunions were excluded. 392 remaining patients were contacted to complete surveys containing PROMIS and CAIT. 127/392 consented. Patients were classified based on ankle instability etiology: active individual (chronic ankle instability without anatomic deformity, n=68), osteochondral defect (OCD, n=22), or deformity (varus/valgus deformity, equinus contracture, n=37). T-tests and Kruskal-Wallis tests were used to assess associations. This study reached 80% power to detect minimum effect size of 0.52 (Cohen's d), corresponding to differences of 4.37 for PF and 4.60 for PI, and 80% power to detect an effect size of 1.15, corresponding to an actual difference in CAIT of 9.24. Results: PROMIS PF by etiology was significant (P=.04). Deformity had lowest PF (48.0±8.1), while active individuals had highest PF (51.6±8.8). Although PI was highest among patients with deformities (51.9±9.8), this did not reach significance compared to PI for patients with OCDs and active individuals (P=.19). Compared to non-augmented, augmented Broström resulted in higher PF and lower PI for deformities (PF 49.7±7.8 vs. 41.9±6.0, P<.01; PI 49.9±7.8 vs. PI 58.8±6.0, P=.04) and active individuals (PF 53.5±7.6 vs. 49.5±9.6, P=.06; PI 46.9±7.6 vs. 50.5±9.6, P=.09) while demonstrating similar PF and PI for OCDs (PF 51.2±9.3 vs. 51.5±4.1; P=.92 and 50.2±9.3 vs. 46.3±4.1, P=.31). CAIT was higher in augmented Broström among active individuals (21.9±8.0 vs. 16.7±11.4, P=.04), OCDs (20.5±9.3 vs. 20.1±7.2, P=.92), and deformities (19.1±7.9 vs. 12.8±8.5, P=.09). Conclusion: Although deformities had worse PROMIS scores than active individuals, Broström with InternalBrace augmentation enables patients with deformities to achieve PROMIS scores equivalent to population means and CAIT scores similar to active individuals without deformity. For patients with deformity, augmentation was associated with increased PROMIS and CAIT scores compared to non-augmented that exceed the lower end values of minimal clinically important difference ranges reported in the literature for both PROMIS and CAIT. Our findings suggest that augmented Broström may enable patients to achieve improved functional outcomes and ankle stability compared to non-augmented Broström, particularly among patients with baseline deformity.