The position and morphology of the peroneus longus tubercle in hallux valgus – a weight-bearing CT assessment

C. Marusza, H. Stringer, J. Redfern, D. Sangoi, M. Welck, L. Mason, K. Malhotra

Introduction: The peroneus longus tendon, as one of the only dynamic stabilisers of the first ray has the theoretical possibility to be defunctioned in hallux valgus (HV). In this study, our primary outcome was to report and compare the position and morphology of the peroneus longus tubercle (PLT) in feet with and without HV, using weight-bearing CT (WBCT).
 

Methods: A retrospective analysis of WBCT scans was completed using 40 feet in 23 patients. Feet were divided into two groups – the normal, ‘non-hallux valgus’ (non-HV) group and the ‘HV’ group. The morphology and position of the PLT was assessed between groups. We assessed the tubercle-to-floor distance (T-F distance), the bisecting angle, tubercle-to-metatarsals angle (T-MT angle) and metatarsal cross-sectional area.
 

Results: Between the non-HV group and the HV group, significant differences were found in the T-F distance, illustrating a lower medial column in the HV group.  There was a moderate correlation between Intermetatarsal angle (IMA) and T-F distance (r = -.463, p < .001) confirming depression of the first ray with increasing IMA. The bisecting angle was also significantly lower in the HV group as compared to the non-HV group, demonstrating the pronation of the PLT in relation to the floor in the HV group. There was no statistical difference in T-MT angle between the HV and non-HV group thus the pronation appeared to represent the entire forefoot not only the 1^st metatarsal. The size of the cross-sectional area of the PLT was significantly smaller in the HV group as compared to the non-HV group.

Conclusions: In this study we have demonstrated a difference in both the position and morphology of the PLT between HV and non-HVA individuals, with a pronated and hypoplastic PLT noted in individuals with HV.