Outcomes of augmented versus non-augmented broström for lateral ankle instability in the setting of ankle deformity.

BACKGROUND

It is unclear whether Broström with InternalBrace™ augmentation enables patients with structural cavovarus deformity to achieve satisfactory patient-reported outcomes. Patient Reported Outcomes Measurement Information System (PROMIS) measures of physical function (PF) and pain interference (PI) are validated metrics of orthopaedic foot and ankle clinical outcomes. The Cumberland Ankle Instability Tool (CAIT) is a validated metric of ankle stability. This study aimed to determine whether augmentation results in better PROMIS and CAIT for patients with deformities compared to non-augmented.

METHODS

37 patients with cavovarus deformity who underwent lateral ankle ligament reconstruction at a single institution between 2013 and 2024 were retrospectively reviewed. Two investigators independently evaluated all records. Revisions, allografts, nonanatomic reconstructions, flexor digitorum longus transfers, progressive collapsing foot deformities, concomitant hindfoot arthrodesis, associated ankle arthroplasties, and concomitant fractures were excluded. Cavovarus deformity was defined radiographically by an increased talo-first metatarsal angle, or Meary's angle, (>4° convex upward), elevated calcaneal pitch (>30°), increased first metatarsal-calcaneal angle, or Hibb's angle, (>45°), and a decreased talocalcaneal angle (<20°). Patients completed surveys containing PROMIS and CAIT. T-tests and Kruskal-Wallis tests assessed associations.

RESULTS

Overall, the mean PROMIS PF and PI in patients with structural deformity were 48.0 ± 8.1 and 51.9 ± 9.8, respectively. Compared to non-augmented Broström, augmentation resulted in significantly higher PF and lower PI for patients with deformities (PF 49.7 ± 7.8 vs. 41.9 ± 6.0, p < 0.01; PI 49.9 ± 7.8 vs. 58.8 ± 6.0, p = 0.04). Postoperative CAIT was not significantly different between augmented and non-augmented (19.1 ± 7.9 vs. 12.8 ± 8.5, respectively p = 0.09).

CONCLUSIONS

Augmented Broström may enable patients with structural ankle deformity to achieve improved functional outcomes compared to non-augmented Broström, as augmentation resulted in both statistically and clinically significant improvements in PROMIS PF and PROMIS PI compared to non-augmented.

LEVEL OF EVIDENCE: III.