Reconceptualizing the Juvenile Bunion

Background: The operative management of the juvenile bunion has not enjoyed the same level of success as its adult counterpart leading to the concern that we do not fully understand what differentiates these 2 deformities. This study aims to (1) characterize the radiographic and pedobarographic features commonly encountered in the juvenile bunion and (2) determine which of these radiographic or pedobarographic parameters correlate with patient-reported outcome (PRO) scores at the time of presentation. Methods: An IRB-approved retrospective analysis of prospectively enrolled patients between 10 and 18 years of age with bunion deformities was performed at a single pediatric institution over a 4-year period. Standardized weight-bearing radiographs were used to determine hallux valgus angle (HVA), intermetatarsal angle, sesamoid position (SP), distal metatarsal articular angle (DMAA), and other radiographic parameters. Pedobarographic analysis was used to determine peak pressure, contact area, contact time, and pressure-time integral within 11 plantar regions. Foot-specific PRO measures were administered at the initial presentation. Results: Thirty-two patients (57 feet) met the inclusion criteria of which56/57 feet (98.2%) had an elevated DMAA (average 21.4degrees±8.9 degrees), and 51/57 (89.4%) had a congruent joint. The DMAA correlated positively with the HVA (r=0.734 P<0.001), intermetatarsal angle (r=0.439 P=0.001), and SP (r=0.627 P<0.001). Pedobarographic analysis (available in 15/32 patients) demonstrated that the HVA correlated with increased second metatarsal head peak pressure (r=0.667 P=0.011) and pressure-time integral (r=0.604 P=0.002), which in turn was strongly correlated with worse PROs. Conversely, increased first metatarsal head contact area correlated with improved PROs. Analysis of radiographic measurements demonstrated that HVA and lateralized SP correlated significantly with worse PRO scores. Conclusions: Nearly all juvenile bunions have an elevated DMAA and a congruent joint. There is a clear correlation between the severity of radiographic and pedobarographic deformity and worse PRO scores at the time of presentation. We believe that the presence of elevated DMAA is the defining factor that differentiates the juvenile bunion from the deformity typically seen in adults. Level of Evidence: III.