Pes Cavus and Hindfoot Varus Alignment Are Associated with Increased Rates of Peroneal Tendon Pathology

CATEGORY: Hindfoot, Midfoot/Forefoot INTRODUCTION/PURPOSE: Cavovarus foot alignment has been significantly associated with increased rates of chronic ankle instability and osteochondral lesions of the talus. Clinical wisdom suggests that cavovarus foot alignment causes varus stress to the ankle and also predisposes individuals to peroneal tendon pathology. However, no studies have specifically explored this relationship. The purpose of this research is to investigate the association between foot alignment and peroneal tendon pathology. METHODS: A retrospective case-control study was conducted of all adult patients in whom a magnetic resonance image (MRI) of the ankle was obtained for any reason at a single institution from 2015-2017. Patients were excluded if they had a charcot foot deformity or if they had undergone prior peroneal tendon, ankle, or hindfoot surgery. Arch alignment was evaluated on lateral weightbearing radiographs of the foot by measuring the adjusted navicular height. Hindfoot alignment was assessed using the Saltzman apparent moment arm method. Peroneal tendon pathology including tears, tendinosis, and tenosynovitis was documented by a fellowship-trained musculoskeletal radiologist using the MRI scan. All numerical variables were converted to categorical variables (e.g. varus, valgus, and normal alignment). Chi-square testing was utilized to determine the association between variables. RESULTS: 195 patients were included in the study (average age 47 years, 61% female). Patients with hindfoot varus had significantly higher rates of peroneus longus (PL) and peroneus brevis (PB) tendon pathology than patients with neutral or valgus alignment (Figure 1 A, B)(PL 39% vs. 31% vs. 20%, p=0.01; PB 44% vs 27% vs. 27%, p=0.04). Patients with pes cavus demonstrated extremely high rates of peroneal tendon pathology, which was significantly higher than patients with neutral or pes planus alignment (Figure 1 C, D)(PL 71% vs. 28% vs. 9%, p<0.0001; PB 75% vs 30% vs. 26%, p<0.0001). Amongst patients with peroneal tendon pathology, there was no difference in the rates of symptomatic vs. asymptomatic findings based on hindfoot or pes alignment. CONCLUSION: This is the first study to demonstrate a statistically significant association between cavus foot alignment, hindfoot varus alignment, and peroneal tendon pathology. Interestingly, this study demonstrates that patients with cavovarus alignment are not more likely to be symptomatic than patients with normal and planovalgus alignment. This study also reinforces the idea that peroneal pathology found on MRI may not necessarily need surgery, as it is frequently seen in patients without symptoms. This information may be useful in counseling patients considering operative treatment for peroneal tendon pathology and alignment abnormalities.