Relationship between Demographic and Radiographic Characteristics and 2nd Ray Pathology in Hallux Valgus Patients

Category: Bunion; Midfoot/Forefoot Introduction/Purpose: Hallux valgus can alter load bearing in the foot and may result in secondary pathologies such as hammertoes of the second ray. However, there has been little research on the development of second ray pathology in patients with pre-existing hallux valgus. Additionally, most research examining these three-dimensional foot deformities relies on two- dimensional plain radiographs. The goal of this study was to determine if hallux valgus is associated with second ray hammertoes using three-dimensional weightbearing CT scans. Methods: 71 patients who underwent a modified Lapidus procedure for hallux valgus and had preoperative weightbearing CT scans were separated into 2 outcome groups: (1) hallux valgus only (47 feet), and (2) hallux valgus with second ray hammertoe (29 feet). Preoperative age, BMI, sex, hallux valgus angle (HVA), intermetatarsal angle (IMA), absolute and effective first, second, and third metatarsal lengths, the ratios between metatarsal lengths, Meary’s angle, metatarsus adductus angle (MAA), and pronation were measured. Mean values of continuous variables were compared using one-way ANOVA tests or Kruskal-Wallis tests. Simple logistic regression models were created to evaluate associations between variables and hammertoe occurrence: (1) comparing hammertoe to hallux valgus only, (2) comparing hammertoe to hallux valgus with mild hammertoe removed, and (3) comparing hammertoe to hallux valgus with severe hammertoe removed. Multivariable logistic regression models were generated to evaluate potential risk factors for hammertoe after adjusting for patient age and BMI. Results: Patients in the hammertoe group were found to be significantly older and have significantly higher BMIs, HVAs, effective second MT lengths, IMAs, and more apex plantar Meary’s angles (all P-values < 0.05). BMI and HVA were also found to be significant predictors of second ray hammertoe in simple logistic regression models (OR=5.66 (95% CI: 1.67-22.79) and OR=4.5 (95% CI: 1.13-21.06), respectively). The multivariable analysis demonstrated that higher IMA and a more apex plantar Meary’s angle were the only significant predictors of second ray hammertoe risk (P= 0.03 and P = 0.01, respectively) once corrected for age and BMI. Conclusion: Significant associations were found between older age, higher BMI, and more severe deformity and the occurrence of hammertoe in hallux valgus patients. These relationships may aid in determining which patients are at a greater risk of progressing to secondary pathologies and which patients could potentially benefit from earlier surgical intervention to correct hallux valgus.