Syndactyly is a condition wherein two or more digits are fused together. It occurs normally in some mammals, such as the siamang and diprotodontia, but is an unusual condition in humans. The term is from Greek σύν, syn together and δάκτυλος, daktulos finger. Classification
Syndactyly can be simple or complex. In simple syndactyly, adjacent fingers or toes are joined by soft tissue. In complex syndactyly, the bones of adjacent digits are fused. The kangaroo exhibits complex syndactyly.Syndactyly can be complete or incomplete. In complete syndactyly, the skin is joined all the way to the tip of the involved digits. In incomplete syndactyly, the skin is only joined part of the distance to the tip of the involved digits.Complex syndactyly occurs as part of a syndrome (such as Apert syndrome) and typically involves more digits than simple syndactyly. Fenestrated syndactyly, also known as acrosyndactyly or terminal syndactyly, means the skin is joined for most of the digit but in a proximal area there are gaps in the syndactyly with normal skin. This type of syndactyly is found in amniotic band syndrome. Simple syndactyly can be full or partial, and is present at birth (congenital). In early human fetal development, webbing (syndactyly) of the toes and fingers is normal. At about 6 weeks of gestation, apoptosis takes place due to a protein named sonic hedgehog, also known as SHH, which dissolves the tissue between the fingers and toes, and the webbing disappears.
Bertolottis syndrome is a commonly missed cause of back pain which occurs due to lumbosacral transitional vertebrae (LSTV). It is a congenital condition but is not usually symptomatic until ones later twenties or early thirties. However, there are a few cases of Bertolottis that become symptomatic at a much earlier age. It is named for Mario Bertolotti, an Italian physician who first described it in 1917. Presentation
A chronic, persistent low back pain along with buttock pain is the most important presentation. Radicular pain is observed. Pathophysiology
Bertolottis syndrome is characterized by sacralization of the lowest lumbar vertebral body and lumbarization of the uppermost sacral segment. It involves a total or partial unilateral or bilateral fusion of the transverse process of the lowest lumbar vertebra to the sacrum, leading to the formation of a transitional 5th lumbar vertebra. Of importance is that this syndrome will result in a pain generating 4th lumbar disc resulting in a "sciatic" type of a pain correlating to the 5th lumbar nerve root. Usually the transitional vertebra will have a "spatulated" transverse process on one side resulting in articulation or partial articulation with the sacrum or at time the ilium and in some cases with both. This results in limited / altered motion at the lumbo-sacral articulation. This loss of motion will then be compensated for at segments superior to the transitional vertebra resulting in accelerated degeneration and strain through the L4 disc level which can become symptomatic and inflame the adjacent L5 nerve root resulting in "sciatic" or radicular pain patterns.