Saber Shins · What Are They, Causes, and More

Congenital syphilis is one source of saber shins. Syphilis is a bacterial infection caused by the bacterium Treponema pallidum, and congenital syphilis is passed from a pregnant individual who has untreated syphilis to their fetus. When an infant is born with syphilis, the infection may spread throughout their body. As bones continue to grow throughout childhood, the infection may alter the bone growth in the tibia, thereby causing saber shins. 

Rickets, the softening and weakening of the bones in childhood, is another cause of saber shins. Rickets is a result of prolonged vitamin D deficiency, most often due to lack of exposure to sunlight or foods containing vitamin D (e.g., fish, milk), and it can lead to impaired or abnormal bone growth.

Saber shins may be associated with other symptoms of congenital syphilis or rickets. Early symptoms of congenital syphilis include runny nose, canker sores in the mouth, tenderness of the bones, and yellowing of skin and eyes (i.e., jaundice). After one year of age, symptoms may include deafness, as well as joint pain and swelling. When symptoms present after the child turns two years old (i.e., late-onset congenital syphilis), symptoms may include Hutchinson’s teeth, which are small, spaced apart, and may have an uneven shape; “mulberry” molars, which feature rounded cusps or bumps on the chewing surface; saddle nose, in which the nasal bridge collapses in; saber shins; and additional characteristic symptoms.

Other symptoms of rickets that may accompany saber shins in older children and adolescents include delayed growth, thick ankles and wrists, a spine bent forward or backwards, and a widened chest. 

Saber shins are often diagnosed through a clinical examination, including review of the child’s symptoms and the gestational parent’s medical history. Following the clinical exam, blood tests are often conducted in order to diagnose the underlying cause. Blood tests typically include an assessment of the individual’s vitamin D levels and presence of syphilis antibodies. X-ray imaging can confirm the presence of saber shins and assess for any changes in bone density. Occasionally, a lumbar puncture, in which a needle is inserted into the spinal column to retrieve cerebrospinal fluid, is performed to confirm the presence of T. pallidum.

Saber shins caused by syphilis are treated with penicillin G, an antibiotic. Penicillin G is typically administered as an injection into the shoulder muscle of children with congenital syphilis who are at least two years old. Rickets is treated with vitamin D supplements, often accompanied by calcium supplements.

Saber shins can be prevented by testing pregnant individuals for syphilis early in their pregnancy and treating indicated syphilis infections accordingly.

Saber shins are a malformation of the tibia that presents with anterior bowing of the tibia, usually caused by congenital syphilis or rickets. If caused by syphilis, saber shins typically appear along with other symptoms of syphilis, such as Hutchinson’s teeth and mulberry molars. If caused by rickets, saber shins may be accompanied by additional bone deformities, like thick wrists and ankles. Diagnosis generally involves a clinical examination, blood tests, and an X-Ray. Injection of penicillin G into the shoulder muscle is the typical treatment for congenital syphilis, while vitamin D supplementation is needed to treat rickets.