Usually, the large joints of the lower limb are aligned in a straight line, which represents the mechanical longitudinal axis of the leg, the Mikulicz line. This line stretches from the hip joint (or more precisely the head of the femur), through the knee joint (the intercondylar eminence of the tibia), and down to the center of the ankle (the ankle mortise, the fork-like grip between the medial and lateral malleoli). In the tibial shaft, the mechanical and anatomical axes coincide, but in the femoral shaft they diverge 6°, resulting in the femorotibial angle of 174° in a leg with normal axial alignment. A leg is considered straight when, with the feet brought together, both the medial malleoli of the ankle and the medial condyles of the knee are touching. Divergence from the normal femorotibial angle is called genu varum if the center of the knee joint is lateral to the mechanical axis (intermalleolar distance exceeds 3 cm), and genu valgum if it is medial to the mechanical axis (intercondylar distance exceeds 5 cm). These conditions impose unbalanced loads on the joints and stretching of either the thighs adductors and abductors.The angle of inclination formed between the neck and shaft of the femur (collodiaphysial angle) varies with age—about 150° in the newborn, it gradually decreases to 126–128° in adults, to reach 120° in old age.
Polysyndactyly is a hereditary anatomical malformation combining polydactyly and syndactyly. There is also a type called crossed polysyndactyly. Signs and symptoms
The way polysyndactyly presents itself varies; when the webbing is mild, it gives the appearance of the extra digit being partially connected to the (otherwise normal) digit next to it, when the webbing is extreme, the extra digit and the digit next to it will have the appearance of one rather enlarged digit (macrodactyly) and will have two or more finger/toe nails growing in the same digit (polyonychia). How the nails look will also vary, from separate supernumerary finger/toe nails to one very wide finger/toe nail. References
External links
Polysyndactyly and Marfans syndrome The case of an Egyptian Jewish family with 17 affected members. The mother also had Marfans syndrome, which she passed on to a daughter who did not have polysyndactyly.