Abstract
BackgroundsThough malalignment of lower legs is a common pathologic phenomenon in multiple hereditary exostoses (MHE), relationship between locations of exostoses and malalignment of lower legs remains unclear. This study examined radiographs of MHE patients in an attempt to evaluate the tendency of coronal malalignment of lower legs with different location of exostoses on lower legs consisting of two parallel long bones.MethodsBetween 2000 and 2017, we retrospectively reviewed the anteroposterior films of the teleo-roentgenographics of 63 patients with MHE. The patients were classified into four different groups depending on the locations of the exostosis, which occurred on both proximal and distal tibiofibular joints (A), proximal tibiofibular joint (B), distal tibiofibular joint (C), and not for the tibiofibular joint area (D). To evaluate the influence of the location of exostoses on coronal malalignment of lower legs, medial proximal tibia angle (MPTA), lateral distal tibia angle (LDTA), and fibular shortening were analyzed for each group.ResultsSignificant difference was observed in multiple comparative analyses for each of the four groups. On MPTA radiologic analysis, group A showed greatest value with significant difference compared with groups C and D (vs. (B): p = 0.215; vs. distal joints (C): p = 0.004; vs. (D): p = 0.001). Group B showed significant difference only with group D (vs. distal joints (C): p = 0.388; vs. (D): p = 0.002), but for group C and D showed no significant difference. For LDTA, only group A showed significant difference compared to other groups (p < 0.001). With regard to tibiofibular ratio for evaluation of fibular shortening, group A showed the lowest ratio (vs. (B): p = 0.004; vs. (C): p = 0.655; vs. (D): p < 0.001). Group C also presented the significant lower ratio than group D (p = 0.002).ConclusionsFor evaluation of the coronal malalignment of lower legs in MHE patients, not only ankle around the distal tibiofibular joint but also proximal tibiofibular joint should be examined, in that, lower limb deformity occurred by two parallel long bone which has self-contained joint.Level of evidenceLevel III, retrospective comparative study.
Highlights
Multiple hereditary exostoses (MHE), with an estimated frequency of at least once per 50,000, is one of the most common bony dysplasia occurring in the metaphysis of bones developed by endochondral ossification [1, 2]
Considering that the lower legs below the knee joint consist of two parallel long bones, which influence bony growth, proximal articular area should be considered as an important factor for review of deformities of ankle valgus presented as tibia bowing
Group A showed significant difference compared to other groups except for group C (vs. (B): p = 0.004; vs. (C): p = 0.655; vs. (D): p < 0.001)
Summary
Multiple hereditary exostoses (MHE), with an estimated frequency of at least once per 50,000, is one of the most common bony dysplasia occurring in the metaphysis of bones developed by endochondral ossification [1, 2]. The growths may alter bony development and lead to angular deformity with or without subsequent length discrepancies. The relative shortening of the fibula and obliquity of the distal tibia epiphysis results in valgus deformities of the ankle [4–7]. Osteochondromas in distal tibiofibular articular area may impart a tethering effect to lateral growth in distal joint, resulting in valgus deformity in the ankle [8]. Several authors have reported ankle valgus deformities in distal tibiofibular articular area around the ankle joint in patients with osteochondroma [9–11]. Considering that the lower legs below the knee joint consist of two parallel long bones (such as forearms), which influence bony growth, proximal articular area should be considered as an important factor for review of deformities of ankle valgus presented as tibia bowing. There exists no report about coronal malalignment in MHE involving both the lower legs
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