O3232: Which Children and Adolescents Are More Likely to Need Surgery for Symptomatic Accessory Navicular?

Background: The accessory navicular (AN) is a common anatomic variant of the foot and affects up to 12% of the population. While most cases remain asymptomatic, symptomatic AN often develops in childhood and adolescence and can impact activity and reduce quality of life. It is unclear which pediatric and adolescent patients respond to conservative treatment and who will need surgery. Our aim was to determine factors that increase likelihood of surgical intervention and elucidate treatment outcomes.

Methods: This single-institution, retrospective case-cohort study included patients age ≤19 presenting 2000-2021 with symptomatic AN and treated with standard-of-care. At our institution, patients with symptomatic AN are initially managed conservatively, and only after failing conservative measures would they be indicated for surgery. All 287 surgical cases, suggesting failed non-operative treatment, were identified during the study period (Figure 1). A sub-cohort of 187 patients was randomly sampled from all eligible patients with symptomatic AN.

Baseline characteristics were summarized for surgical cases and for the sub-cohort. Marginal proportional hazard modeling for case-cohort data estimated hazard ratios along with 95% confidence intervals for the effect of various risk factors on likelihood of surgical intervention. All tests were two-sided and p-values less than 0.05 considered significant. Analyses were conducted using the coxphw package and base statistical packages of R software version 4.1.2 (R Core Team; Vienna, Austria).

Results: Females comprised the majority of both the failure (surgical) group and sub-cohort presenting with symptomatic AN (84% surgery cohort, 73% sub-cohort). Soccer, dance/cheer, and basketball were the top three sports.

In the sub-cohort, 46 failures of nonoperative management and 141 non-failures were found, indicating a 24.6% surgery rate for all symptomatic AN. The 287 surgical cases failed non-operative management at a median of 13.7 months (IQR, 5 to 30.0 months; Table 1). Univariable proportional hazard modeling found older age (p=0.04), activity limitation at presentation (p < 0.001), female sex (p=0.008), AN of the right foot (p=0.003), lower Meary’s angle (p=0.04), and bone marrow edema in the AN or navicular body on MRI (p < 0.001) were associated with increased hazard of failure of non-operative management.

Nearly all (269/285, 94%) who underwent surgical intervention reported pain improvement at follow-up. Most (186/271, 69%) had full resolution of symptoms, and 94% (231/245) of those who participated in sports at presentation were able to return to their primary sport.

Conclusion: Symptomatic AN predominantly affects female athletes from soccer, dance, and basketball. Conservative treatment may be less successful in older females presenting with activity limitation, AN on the right foot, pes planus, and bone marrow edema on MRI. In our cohort, approximately 25% of all those presenting with symptomatic AN ended up needing surgery. Overall, surgery is effective and most helpful for improving pain and allowing return to sports.