Clinodactyly is defined as a congenital curvature of a digit distal to the metacarpal phalangeal joint in the coronal plane. Curvatures with an angular deviation of fewer than 10 degrees can be seen as a normal physiologic variant. Clinodactyly is defined when the coronal angulation of the affected digit is greater than 10 degrees. The curvature arises due to the abnormal trapezoidal or triangular shape of one or more phalanges, which leads to malalignment of the associated interphalangeal joint. This abnormal shape leads to asymmetric longitudinal growth in a direction deviated from the normal longitudinal axis of the finger resulting in the visible curvature of the digit.[1]


Clinodactyly can occur in syndromic, familial, and sporadic forms.[2] The trait expresses autosomal dominant inheritance and most commonly involves the middle phalanx of the small finger. Several studies have also documented the involvement of the proximal phalanx of the index finger and thumb.[3] The curvature arises due to the abnormal trapezoidal or triangular shape of one or more phalanges, which leads to malalignment of the associated interphalangeal joint. This abnormal shape leads to asymmetric longitudinal growth in a direction deviated from the normal longitudinal axis of the finger resulting in the visible curvature of the digit.


The incidence of clinodactyly is unknown; however, rates have been reported between 1% and 19.5%. It is often seen bilaterally, and males have been found to be more likely to express the trait. In has been associated with several syndromic anomalies, including Rubinstein-Taybi syndrome, Cenani-Lenz syndactyly, Klinefelter syndrome, Turner syndrome, Fanconi anemia and is present in up to 25% of children with Down syndrome. Clinodactyly is often present in the neonate; however, its presentation typically occurs in later childhood years as the deformity becomes more noticeable as longitudinal growth occurs. Patients present for treatment typically due to the abnormal appearance of the digit; however, the deformity rarely causes functional impairment due to compensatory abduction of the affected digit, which prevents the curvature from obstructing full digit flexion.


Longitudinal growth of the phalanges is driven from epiphyseal growth from the proximal portion of the phalanx. Abnormal configuration of the epiphyseal plate results in the curvature seen in clinodactyly. In clinodactyly, a C-shaped physis is often present and results in incomplete or restricted longitudinal growth on one side of the phalanx. In cases of early complete physeal plate ossification, no longitudinal growth will be possible, and a classic delta phalanx will be produced. The severity of the deformity can vary, and a classification system has been described.[4] Acquired cases of clinodactyly can be seen after traumatic injuries to the epiphyseal plate.[5] Cases of inflammatory and infectious arthritis can also cause longitudinal grown disturbances.[6]

History and Physical

History and physical exam will reveal the curvature of the affected digit in the radial/ulnar plane. It is essential to determine if the deformity affects the radial digits of the hand or if pinch function is compromised due to the deformity. Range of motion testing should be documented, and a complete history should reflect if the deformity is congenital or post-traumatic, stable or progressive.


Plain radiographs can aid in the diagnosis of clinodactyly. A radial or ulnar curvature will be present, and a shortened middle phalanx will often be seen, which is typically shorter on the radial rather than the ulnar side. A C-shaped physis or delta phalanx may also be present on plain radiographs.[7] Occasionally a prenatal ultrasound may identify clinodactyly.

Differential Diagnosis

Differential diagnosis includes traumatic physeal injury, tumor, infection, and osteomyelitis. Clinodactlyly can be associated with several other medical syndromes including Rubinstein-Taybi syndrome, Cenani-Lenz syndactyly, and can be present in up to 25% of children with Down syndrome.


Expected outcomes following surgical intervention include the correction of the deformity.


Complications following surgical correction of deformity include stiffness, over and under correction of deformity, physeal arrest, skin deficits, and infection.[12]

Deterrence and Patient Education

In-depth discussion must be had with the patient and/or family explaining the risks and benefits of surgical intervention that must be reserved for patients with functional deficits, rather than aesthetic or cosmetic concerns. 

Enhancing Healthcare Team Outcomes

An interprofessional team that provides a holistic and integrated approach to diagnosis and treating patients with clinodactyly is imperative. By correctly diagnosing and recognizing surgical indications for clinodactyly, primary care physicians can help avoid the added healthcare costs of possible unnecessary testing, advanced imaging studies, and consultations. The vast majority of cases of clinodactyly can be treated with observation. When more severe cases present, it is important to consult a surgical specialist for any surgical intervention that may be indicated. 

(Click Image to Enlarge)
Clinodactyly of the little finger
Clinodactyly of the little finger
Image courtesy S Bhimji MD
Article Details

Article Author

Devon Banda

Article Editor:

Amjad Yaish


8/10/2020 9:27:10 PM

PubMed Link:




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