Causes / typical injury mechanism: Camptodactyly is a congenital condition that can result from anatomic abnormalities within the flexor digitorum superficialis (FDS) insertion, anomalous lumbrical insertion, or contracture of skin / fascia.

Classic history and presentation: Camptodactyly is present at birth and is more often bilateral than unilateral, with 33% of cases being unilateral and 66% of cases being bilateral. It usually occurs in the proximal interphalangeal (PIP) joint of the small finger.

Prevalence:

• Occurs in less than 1% of the population.
• Age – Present at birth.
• Sex / gender – There is no gender predilection; there can be autosomal dominant inheritance.

Risk factors: Most cases are sporadic; however, 30% of cases are associated with familial history due to autosomal dominant inheritance. It can also be associated with certain syndromes.

Pathophysiology: Abnormal insertion of FDS or lumbricals.

Grade / classification system: Benson classification
Type I:

• Most common type.
• Generally affects the small finger.
• Equal distribution between males and females.

Type II:

• Occurs in childhood, typically between the ages of 7 and 11 years.
• It is more common in females.
• This type does not resolve on its own.

Type III:

• Seen at birth and usually affects several fingers.
• It is usually bilateral and has more severe features.
• This type is associated with syndromes.