Radiographic Evaluation of Congenital and Acquired Foot Deformities: 1st MTP Angle

Purpose

Characterization of congenital and acquired foot deformities on radiographs

Tag(s)

bilateral foot, foot, x-rays, radiographs, congenital foot, pes, feet, 1st MTP angle, 1st metatarsophalangeal angle, weight-bearing

Panel

Pediatric

Define-AI ID

20010016

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 RDES206
                               

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 our 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 1st metatarsophalangeal (MTP) angle to specifically evaluate the presence or absence of hallux valgus. Additional use cases include the AP and lateral talocalcaneal angles, talo-1st metatarsal angle, talonavicular axis, calcaneal pitch, intermetatarsal 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: 1st MTP  angle, comparisons from any available prior studies, and normal vs. abnormal angle.

Considerations for Dataset Development


Procedures

XRAY, Foot

RADIOGRAPH, Foot

Gender

Male, Female

Age (years)

0-18

Views

AP

Technique

Weight-bearing, Simulated weight-bearing, Erect

Anatomy

Foot

Confounders

Cast, Splint, Brace, Non-weight-bearing, Supine

Technical Specifications


Inputs

 

DICOM Study

Procedure

X-ray Foot Radiograph

Views

AP

Data Type

DICOM

Modality

X-ray

Body Region

Lower Extremity

Anatomic Focus

Foot



Primary Outputs


1st MTP Angle   

RadElement ID

RDE1343 

Definition

The angle between the axis of the 1st metatarsal shaft and the axis of the proximal phalanx of the 1st toe on weight-bearing AP foot radiograph.

Data Type

Numeric

Value Set

0-90

Units

Degrees


Secondary Outputs


Normal vs. Abnormal with Grading       

RadElement ID

RDE1344 

Definition

Normal for 1st MTP angle is <15 degrees. A 1st MTP angle >15 degrees is consistent with hallux valgus which can be graded as mild, moderate or severe.depending on the measurement of the 1st MTP angle.

Data Type

Categorical

Value Set

  • normal (<15)

  • mild hallux valgus (15-20)

  • moderate hallux valgus (21-40)

  • severe hallux valgus (>40)

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