Abstract
BackgroundHaving reviewed the studies on the biphalangeal fifth toe, we have observed a great disparity of data depending on the research center. We have investigated the frequency of biphalangeal toes and also its handedness. We have also analyzed the relationship of pathological deviations of fifth toe with this feature and with the fifth metatarsal.MethodsWe performed a descriptive prospective study, which analyzed 2494 feet (1247 people) with bilateral dorsoplantar radiographs. We studied the number of phalanges of the fifth toe, the deviations in the sagittal and transverse plane, and the state of the fifth metatarsal phalangeal joint.ResultsAfter analyzing the data we found the presence of biphalangeal fifth toe in 46.3% of the feet, presenting this feature bilaterally in 97.4% of them. A statistically significant higher percentage of pathological toes was found in people with triphalangeal fifth toe (pathological in 29.91%) than in the biphalangeal toes (pathological in 15.60%). We found that these differences are accentuated in the alterations of the fifth toe in the sagittal plane.ConclusionsIt is almost 4 times more likely to suffer a fifth hammer toe if the fifth toe is triphalangeal (OR = 3.98 to p =0.000). Alterations in the coronal plane of the fifth toe are associated with tailor’s bunion (p =0.000). We did not find any significant differences regarding the need for surgery of the fifth toe of the biphalangeal (39.1%) versus triphalangeal toes (60.9%). Clinical relevance: There may be an association between pathologic deviations and bigger mobility of the triphalangeal fifth toes. However, biphalangeal fifth toes show bigger rigidity leading to smaller accommodation inside the shoe, which may lead to less painful feet and decreased proportion of surgery.Electronic supplementary materialThe online version of this article (doi:10.1186/1471-2474-15-295) contains supplementary material, which is available to authorized users.
Highlights
Having reviewed the studies on the biphalangeal fifth toe, we have observed a great disparity of data depending on the research center
The differences in the proportion of biphalangeal and triphalangeal toes regarding the sex were statistically significant (p = 0.01), showing greater proportion of biphalangeal toes among females compared to males
We discovered differences regarding the type of pathology in the toes (Figure 4): an increase in the proportion of hammer toes, and 4 times greater risk for hammer toe (OR = 3.98; 95% CI (3.15, 5.05); p = 0.000) among individuals with triphalangeal fifth toe as compared with biphalangeal fifth toe
Summary
Having reviewed the studies on the biphalangeal fifth toe, we have observed a great disparity of data depending on the research center. We have investigated the frequency of biphalangeal toes and its handedness. The biphalangeal fifth toe is described since ancient times. In his anatomical plates, Leonardo da Vinci represented the fifth toe with two phalanges [1]. Andrea Vesalius [2] represented the fifth toe with three phalanges clearly differentiated. Historically alterations in the number of phalanges in other toes, in isolation or multiple, are presented less frequently than in the fifth toe (Figures 1, 2). The subject under study is not common in the international scientific literature, relatively recent references can be obtained, dealing with triphalangeal or biphalangeal fifth toe. Some authors have considered the issue is related to ethnicity, since the biphalangeal fifth
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