It is saber shin deformity
Saber shin is a malformation of the tibia. It presents as a sharp anteriorbowing, or convexity, of the tibia.
Differential diagnosis includes yaws, Paget’s disease of bone, Vitamin D deficiency, or Weismann-Netter-Stuhl syndrome and osteomalacia.
It is a classic presentation in congenital syphilis.
Saber shin is a malformation of the tibia. It presents as a sharp anterior bowing, or convexity, of the tibia.
Congenital syphilis (CS) is a disease that seriously affects newborns (NB) in a multisystemic way; it can even be fatal. It occurs through the hematogenous transmission of Treponema pallidumthrough the placenta of untreated or inadequately treated pregnant women to their children.
CS transmission can occur at any gestational stage or clinical stage of maternal disease. Vertical transmission depends primarily on two factors: the stage of syphilis in the mother and the duration of fetal exposure in uterus.
CS is more likely to occur in cases of inadequate prenatal care. It is also more likely to occur in the following cases: mother with primary syphilis; presence of any maternal illness of unknown duration; high maternal titers in non-treponemal plasma tests (VDRL ≥ 1:16) during treatment (or at delivery); small intervals between treatment and delivery (<4 weeks); and untreated syphilis.
CS can be classified as early (diagnosed up to 2 years of age) and late (after this period). The main characteristics of early CS include prematurity, low birth weight, hepatomegaly with or without splenomegaly, cutaneous lesions, limb pseudoparalysis, respiratory distress, jaundice, anemia, and generalized lymphadenopathy. Furthermore, osteitis and osteochondritis are also noteworthy; they present characteristic lesions in a radiological study (as in the present case). Laboratory abnormalities include anemia, thrombocytopenia, and leukocytosis or leukopenia. In the case of the present patient, the presence of a mother with untreated syphilis during pregnancy associated with clinical manifestations in the NB were sufficient to establish the diagnosis of CS. Late CS is characterized by saber shin deformity of the tibia, Clutton’s joints, frontal bossing, saddle nose, deformed upper medial incisor teeth (Hutchinson’s teeth), neurological deafness, and difficulty in learning.
Some authors believe that CS could be primarily reduced by improving prenatal care in the high-risk population and by refining case reporting in order to control syphilis infection in the community. Furthermore, notification of the partners of pregnant women with syphilis has been associated with a marked improvement pregnancy outcome.
It is also known that the annual number of deaths due to CS competes with that of deaths caused by vertical transmission of human immunodeficiency virus (HIV). Since healthcare systems are increasingly investing in the prevention of vertical HIV transmission, it is inexplicable that this practice has not been adopted for syphilis, since the cost of preventing CS by traditional screening is much lower than that of preventing vertical HIV transmission.