July/August 2012
ORIGINAL CONTRIBUTION onychomycosis (DLSO) and even show lateral margin involvement (Figures 4A, B, C, D, G, and I). This would guarantee failure to completely achieve a 100% clinical cure when systemic antimycotic treatment is given to patients with both dermatophyte onychomycosis and AGNUS.15–16 This should be of particular interest to investigators who treat DSO in studies for pharmaceutical companies, because these finding would explain why a patient with DSO after an apparently successful treatment with a systemic antimycotic will remain clinically abnormal yet mycological negative. Furthermore, the evidence presented in this paper would negate the need for a re-definition of “cure,” as has been proposed by a group of dermatologists, podiatrists, and Pharma-associated individuals, in a recent consensus paper regarding the persistence of clinical signs in successfully17 treated mycological (dermatophyte)– negative patients. The nail-shoe trauma is most often the result of an asymmetric gait unsuspected by both the patient and the clinician. It is unlikely that onychomycosis itself leads to an asymmetric walking gait. One might also speculate that an asymmetric walking gait could favor the onset of dermatophyte onychomycosis in the onycholysis secondary to AGNUS. This assumption, however, might be serendipitous.18,19 In a larger series of patients with fungus-negative nail changes, causes other than an asymmetric gait (dysfunctional biomechanics) may surface.
Figure 4. Toe nail unit abnormalities in patients with asymmetric gait nail unit syndrome (AGNUS), which are identical with distal lateral subungual onychomycosis (DLSO), but are fungus-negative with skeletal abnormalities. (A) A linear nail bed (NB) keratosis on lateral aspect of toe. (B) More pronounced involvement. (C) Characteristic nail plate (NP) curvature and onycholysis, typical of DLSO. (D) DLSO-like changes of hallux. Note pressure of shoe on toe skin. (E) X-ray of patient in Figure 4D, showing scoliosis. (F) Patient as in Figure 4D now worsened 6 months later. (G) More severe changes. (H) Minimal NB damage with mild NP AGNS curvature and skin hyperkeratosis. (I) Severe NB keratosis and lateral NP changes. (J) Minimal medial linear NP damage. (K) Shoe sole wear of patients with AGNUS.
CONCLUSIONS
4000 athletes and coined the term short leg syndrome. In 2006, investigators compared scanning vs the full-length standing method and found them comparable.13 A full-length standing radiographic technique was used in our patients. There is no established data to suggest that scoliosis is secondary to the short limb syndrome.14 Patients who have distal subungual onychomycosis (DSO) may also have abnormal foot biomechanics and present additional clinical nail unit changes (asymmetric gait nail unit syndrome [AGNUS]) that are indistinguishable from the category of onychomycosis termed distal lateral subungual SKINmed. 2012;10:213–217
Evidence is presented indicating that commonly seen toenail lesions, that may resemble onychomycosis but are in fact dermatophyte-free, are caused by the friction of the toe and the closed shoe in patients who have variable, often correctable skeletal abnormalities resulting in an asymmetric walking gait due to dysfunctional foot biodynamics. Many of these patients are misdiagnosed as having onychomycosis and are treated with no subsequent improvement in their abnormal clinical toenail. Both dermatophyte onychomycosis and AGNUS can occur together for independent reasons. One may speculate that some of the opportunistic fungi described in the dermatologic literature clinically resembling DSO may occupy and flourish in the onycholysis secondary to AGNUS. Early recognition of the characteristic toenail signs may contribute to the health and quality of life of the patient who has some (one of many) skeletally correctable abnormalities and have onset in the early years that gets worse with age. Acknowledgements: Dock Anderson, DPM and Martin N. Zaiac, MD at the Mount Sinai Medical Center contributed to the preparation of this presentation.
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The Asymmetric Gait Toenail Unit Sign