Long-Term Functional and Radiographic Outcomes of Untreated Tarsal Coalitions: A Community-Based Observational Study.

Background: The natural history of untreated tarsal coalitions is largely unknown. It is thought atypical biomechanics of limited hindfoot motion may contribute to early degeneration and foot pain or dysfunction. Consequently, there is no data on long-term outcomes of nonoperatively managed asymptomatic tarsal coalitions. This study sought to define the frequency of radiographically apparent tarsal coalitions among a cross-section of a population not seeking care for foot symptoms. Ultimately, we aimed to observe the natural history of these coalitions by comparing multiple functional scores and radiographic foot osteoarthritis between participants with and without radiographic coalition to see if coalition presence is associated with worsened scores and or radiographic osteoarthritis.

Methods: Utilizing existing data from a community-based study, radiographs were reviewed for findings of calcaneonavicular (CN) and talocalcaneal (TC) coalitions. Patient and foot-specific outcome scores [patient-reported outcomes measurement information system (PROMIS), foot and ankle outcome score (FAOS)] and radiographic foot osteoarthritis scoring were compared between "Coalition present"(C) and "No Coalition" (NC) groups.

Results: Among 299 participants (592 feet) in this study (mean age: 72 y, 34% male, 41% Black), radiographic coalitions were found in 9.3% of feet, with 6.4% CN and 3.0% TC. PROMIS and FAOS were not significantly different between the NC and C groups. There was no statistically significant association between radiographic osteoarthritis and coalition presence. An unadjusted subanalysis of the coalition subtype found a modest association between CN coalitions and talonavicular osteoarthritis. TC coalitions had marginally worse FAOS symptoms, pain, sports and rec, and QOL subscores, though most TC participants had minimal dysfunction, with >60% reporting mild or no symptoms.

Conclusions: We found few observable relationships between subclinical coalitions and osteoarthritis or clinically significant foot dysfunction. Individuals with TC coalitions may have slightly lower functional scores than participants with no coalition over a lifetime. These data can be used to counsel participants with tarsal coalitions regarding their long-term outcomes. We recommend continued non-operative management of asymptomatic tarsal coalitions.

Level of evidence: Level III.