Radiographic Evaluation of Congenital and Acquired Foot Deformities: Intermetatarsal Angle

Purpose

Characterization of congenital and acquired foot deformities on radiographs

Tag(s)

bilateral foot, foot, x-rays, radiographs, congenital foot, pes, feet, intermetatarsal angle, weight-bearing

Panel

Pediatric

Define-AI ID

20010012

Originator

Pediatrics Panel
Lead Viet Le & Alex Towbin

Panel Chair

Steven Blumer

Panel Reviewers

Pediatric Panel

License

Creative Commons 4.0
Status Public Comment
RadElement Set RDES202
                               

Clinical Implementation


Value Proposition


Multiple angles and measurements can be used to evaluate abnormal development of the foot, but the task of obtaining these can be cumbersome and time-intensive. An automated method for obtaining a series of angle measurements and bony relationships, which can eventually be used to characterize foot deformities, should improve the radiologists’ workflow.

For this use case(s), we will first focus on automating the measurement of a series of different angles and bony associations on foot radiographs, which can then be compiled to determine the presence vs. absence of a foot deformity. If present, our hope is for the algorithm to further diagnose/characterize the specific foot deformity. Ultimately, this may be expanded to include additional modalities, such as CT.

For this particular use case, we will limit our evaluation to measuring the intermetatarsal angle. Additional use cases include the AP and lateral talocalcaneal angles, talo-1st metatarsal angle, talonavicular axis, calcaneal pitch, 1st metatarsophalangeal angle, Meary’s angle, and the tibial-calcaneal angle.

Narrative(s)


3 year-old female presents to the pediatrician with abnormal gait and in-toeing. Bilateral, weight-bearing 3-view foot radiographs are obtained for evaluation of foot deformities.

6 month-old male presents for contractures/abnormal positioning of the feet. Bilateral, 3-view simulated weight-bearing foot radiographs are obtained for evaluation of foot deformities.


Workflow Description


Radiographs of the foot/feet are ordered, obtained, sent to PACS and the algorithm is triggered.


The algorithm delivers the following outputs: intermetatarsal angle, comparisons from any available prior studies, and normal vs. abnormal angle

Considerations for Dataset Development


Procedures

X-ray, Foot

Radiograph, Foot

Gender

Male, Female

Age (years)

0-18

Views

AP

Technique

Weight-bearing or Simulated weight-bearing

Anatomy

Foot

Confounders

Cast, Splint, Brace, Non-weight-bearing, Supine, Surgical and post traumatic change

Technical Specifications


Input

 

DICOM Study

Procedure

X-ray, Foot Radiograph

Views

AP

Data Type

DICOM

Modality

X-ray

Body Region

Lower Extremity

Anatomic Focus

Foot


Primary Outputs

 

Intermetatarsal Angle   

RadElement ID

RDE1335 

Definition

The angle between the 1st and 2nd metatarsal shafts on weight-bearing AP foot radiograph.

Data Type

Numeric

Value Set

0-90

Units

Degrees


Secondary Outputs 

 

Normal vs. Abnormal   

RadElement ID

RDE1336 

Definition

Normal intermetatarsal angle is <9 degrees.

Data Type

Categorical

Value Set

  • normal (<9)

  • abnormal (>9)

Units

N/A

Future Development Ideas


As mentioned in the Value Proposition, future development ideas include

  • Additional angle measurements

  • Bony relationships in the foot

  • Diagnosis of foot deformities if present (“diagnostic use cases”)

  • Improvement from prior studies if comparisons are available

  • Extrapolation to another imaging modality, such as CT