Subungual Exostoses as an Infrequent Cause of Pain and Nail Plate Deformities of the First Toe: A Retrospective Cohort Study

Background: Toenail deformities are a frequent reason for medical consultation. The etiology is not always well understood, particularly in cases without trauma, where abnormal nail growth conditions have been excluded, and microbiological cultures yield negative results. Thus, identifying the underlying cause of toenail anomalies can be challenging. Patients often do empirical treatments—i.e., antifungals—for extended periods without achieving remission. Subungual exostoses, on the other hand, are an important consideration in the differential diagnosis of subungual pain, particularly in the first toe. Although exostoses have been well documented in the literature, studies specifically examining their role in nail deformity and discomfort are lacking. Methods: A retrospective analysis was conducted on 173 feet of patients with weightbearing lateral radiographs. These radiographs were classified into two groups based on the presence or absence of subungual exostoses, and we collected patient history data focusing on the presence or absence of pain localized beneath the nail and associated nail abnormalities. Results: Subungual exostoses were observed in 52% of the sample, whereas nail disorders were identified in 18.5%. Notably, among patients with nail disorders, 78% (25 patients) also presented with subungual exostoses. Subungual pain was reported in 25 patients (14.5%), of whom 76% had subungual exostoses. Conversely, the prevalence of subungual exostoses was lower in patients without nail abnormalities (46%) or subungual pain (48%). Statistically significant associations were found between nail abnormalities and the presence of exostoses and subungual pain and exostoses, as well as pain and nail deformities (p < 0.05). Conclusions: Both pain and nail abnormalities may be considered to have a high positive predictive value for the presence of subungual exostoses.