Regional Bone Density Analysis of Minimally Invasive Bunionette Fixation Target Sites

Minimally invasive hallux valgus correction has gained a presence in the foot and ankle community because of its minimalist approach and reproducibility. Minimally invasive techniques have also gained popularity in other facets of foot and ankle surgery, including bunionette correction. The main objective of this study was to evaluate computed tomography (CT)-derived Hounsfield units (HUs) from four quadrants of the fifth metatarsal head evaluating regional bone density.

A retrospective analysis was conducted of 30 patients without a history of osteoporosis, fracture, or previous surgery who underwent CT examination. The fifth metatarsal head was separated into quadrants in the coronal plane and CT-derived HUs from a 3.5-mm region of interest centered in each quadrant were obtained. Quadrant HU values were compared using an analysis of variance followed by post hoc testing. The threshold for statistical significance was set at P ≤ .05.

The average cohort age was 43 ± 15 years. The sample was composed of 20 females (67%) and ten males (33%). There existed a statistically significant difference among the fifth metatarsal head quadrants (P < .001). The dorsomedial quadrant density was 301.0 ± 76.4 HUs, which post hoc analysis revealed to be greater than the dorsolateral (186 ± 68 HUs; P = .001), plantar medial (241 ± 69 HUs; P = .007), and plantar lateral (214.0 ± 70 HUs; P = .001) quadrants.

During fixation in minimally invasive bunionette deformity correction, the dorsomedial quadrant of the fifth metatarsal head remains the optimal fixation target site according to regional bone density. Adding to the reproducible minimally invasive surgical technique, surgeons should plan the trajectory to capture this dorsomedial quadrant during fixation.