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The characteristic morphology of the nail unit is determined at the moment of conception by the chromosomal content of the zygote. Subsequent mitotic events including deletion, duplication, breakage, etc. also may contribute to nail deformity. In utero conditions are another factor that may affect the appearance of the nail unit. This article identifies conditions of the nail unit that are congenital in nature and deserve special attention to treatment plans that may or may not be beneficial.

The invasion of human toenails by microorganisms is not always understood. Efficacious treatment, however, depends on establishing proper identification and understanding the improper diagnosis results in failed treatment. Most medical treatment presently is directed toward several fungal species. This article identifies these organisms by means of diagrams and transmission and scanning electron microscopy. The article also discusses microorganisms that are unresponsive to dermatophytic treatment and discusses how aspergillus, saprophytes, and yeasts can affect nails and mimic dermatophytic infections.

The nail unit is distinctive for human beings. Developmentally, the fetus demonstrates cranial and caudal paired anlage of the upper and lower extremities. The leg bud develops a foot plate and eventually toe rays that are first notched, later webbed, and then develop into separate toes. Distal on the toe, the primitive nail unit appears and eventually moves dorsal. When developed fully, the nail unit consists of the nail plate, nail bed, ungualabia, eponychium, hyponychium, lunula, and nail matrix. These structures are associated intimately with the terminal or ungual phalanges of the foot's five toes.

In this excellent article, Dr. McCarthy presents some of the most current concepts in the treatment of lower extremity ulcerations. This common clinical finding is frequently frustrating and difficult to treat effectively. It also requires a high degree of suspicion as to the primary underlying cause and many hours of careful treatment and follow-up to prevent serious secondary complications, such as infection and gangrene. The emphasis on therapeutic approaches lends much useful information in our fight with this condition and its sequelae.

Pes planus or flatfoot becomes a medical problem only when symptoms develop. The mere absence of a well-formed medial longitudinal arch does not necessarily imply pathology. Many apparently "flat feet" demonstrate congruent joints, and the extremities function normally. The size and shape, as well as the angles of declination for the talus or astragulers and the calcaneus or os calcis, are most often determined at the moment of fertilization by the genes of the patients. The zygote or fertilized ovum is a first totipotent. Cell division normally occurs as development proceeds, but the embryo is vulnerable to alterations of the cell cycle. Teratogenic substances can induce death or substantial structural modifications to the developing fetus. The post-World War II tragedy of the medical use of the drug thalidomide in pregnant mothers resulting in amelia is testimony as to how the lower extremity can be adversely affected. Early chromosomal aberrations including duplication, deletion, breakage, inversion, translocation, and mosaicism have been shown to be involved in faulty development of the foot, and there is no reason not to implicate pes valgo planus to these events. Intrauterine development apart from the genetic considerations just mentioned place the fetus under additional jeopardy. Even extraembryonic membranes can form strands of tissue that can entangle the delicate developing foot plate, and calcaneovalgus deformities could conceivably be established. The developing embryo and fetus first demonstrate a blastema that forms limb buds on the ventral caudal aspect. Anlage of the scleroblastema and myoblastema of the prospective leg and foot develop in the presence of nerve trunks. Such nerves are related to the lumbosacral plexus and they are thought to exert inductive developmental influences. Interference with any of these events may be implicated in pedal deformities such as pes valgo planus. This is also true of subsequent morphogenetic events involving embryonic rotations, osteogenesis, and myogenesis. Many pedal deformities have congenital basis and it is clear that pes valgo planus is one of them. Post-natal structural changes further accentuate underlying etiologies. For example, the calcaneus normally exhibits a varus position at birth, but this feature diminishes until the cessation of bone growth. The adult talar neck-calcaneal angle is normally about 24 degrees, representing a 6-degrees reduction from that of 30 degrees, which is demonstrated at birth.(ABSTRACT TRUNCATED AT 400 WORDS)

Dr. McCarthy has written several outstanding papers on the identification, ultrastructure, and treatment of this very common condition. In this article, he has placed together the most important therapeutic approaches used in today's podiatric offices and clinics in a clear and easy to read manner. Also, in typical McCarthy style, the amount of academic teaching in this information makes it even more fun to read.