Characteristic factors of ankle valgus with multiple cartilaginous exostoses.

BACKGROUND

Ankle valgus is one of the most common deformities in multiple cartilaginous exostoses (MCEs). However, the characteristic factors of ankle valgus are not well known.

METHODS

To determine the characteristic factors of ankle valgus in MCE, we investigated 62 ankles in 33 patients (23 males, 10 females) with no history of surgical treatment of ankles with MCE. Mean age at investigation was 11 years 4 months (range, 2 years 7 months-17 years 1 month). We evaluated Taniguchi classification, tibiotalar angle (ankle valgus), site of exostoses in the distal tibia and distal fibula, fibular shortening (Malhotra classification), and correlations between these factors.

RESULTS

According to Taniguchi classification, patients were classified as group II (n = 8), group III (n = 18), or unknown (n = 7). Mean tibiotalar angle was 5.1 degrees (range, -4 to 20 degrees) in males and -0.8 degrees (range, -5 to 7 degrees) in females. Significant differences in ankle valgus were found between sexes within the same age group, and ankle valgus progressed with age in males. Ankles with involvement of both lateral distal tibia and medial distal fibula showed significantly more severe ankle valgus than ankles with involvement of the lateral distal tibia alone or no involvement. In Malhotra classification, all except 1 ankle showed station 0 in females. All cases of station II or III involved males and degree of fibular shortening correlated with ankle valgus in males. Taniguchi group III was associated with more frequent involvement of both lateral distal tibia and medial distal fibula in males, and greater frequency of both fibular shortening and ankle valgus with >or=10 degrees was seen compared with Taniguchi group II.

CONCLUSIONS

Several characteristic factors of ankle valgus in MCE seem to predict progression.