Leg Length Discrepancy

Purpose

Evaluate for discrepancy in leg length

Tag(s)

 

Panel

Pediatric

Define-AI ID

20010007

Originator

Morgan McBee
Lead Morgan McBee

Panel Chair

Steven Blumer

Panel Reviewers

Pediatric Panel

License

Creative Commons 4.0 
Status Public Comment
RadElement Set RDES172
                               

Clinical Implementation


Value Proposition


When there is a concern for a leg-length discrepancy, the lengths of the legs are evaluated with radiographs, which not only allow for quantification of length but also allow for assessment of the underlying cause of the discrepancy of the lengths of the legs.


Narrative(s)


Over a 6 month period, a mother has noticed that her 7-year-old child has developed a progressive limp. The child is not experiencing any pain, but the mother is concerned by the limp and takes the child to be evaluated by an orthopedist. The orthopedist orders a leg length study. 


Workflow Description


An x-ray is taken and sent to PACS and the AI engine. The algorithm is triggered automatically by a leg length study. This algorithm returns the length of each femur and tibia as well as the total length of each lower extremity. Additionally, it also determines the presence or absence of a mechanical axis deviation by drawing joint orientation angles around the knee and also determines if there is a pelvic tilt.



Considerations for Dataset Development



Procedure

Leg Length Discrepancy Plain Radiograph

Views

AP Frontal View of the lower extremities

Age

Children less than 18 years of age

Technical Specifications


Input

 

DICOM Study

Procedure

Leg length discrepancy

Views

Frontal

Data Type

DICOM

Modality

Radiograph

Body Region

Lower extremities

Anatomic Focus




Primary Outputs


Right lower extremity length

RadElement ID

RDE1178

Definition

Total length of the right lower extremity measured from the apex of the right femoral head to the center of the right tibial plafond.

Data Type

Numeric

Value Set

N/A

Units

cm


Left lower extremity length

RadElement ID

RDE1179

Definition

Total length of the left lower extremity measured from the apex of the left femoral head to the center of the left tibial plafond.

Data Type

Numeric

Value Set

N/A

Units

cm


Right femur length

RadElement ID

RDE1180

Definition

Length of the right femur measured from the apex of the right femoral head to the distal medial right femoral condyle.

Data Type

Numeric

Value Set

N/A

Units

cm


Right Tibia length

RadElement ID

RDE1181

Definition

Length of the right tibia measured from the medial right femoral condyle to the center of the right tibial plafond.

Data Type

Numeric

Value Set

N/A

Units

cm




Left Femur length

RadElement ID

RDE1182

Definition

Length of the left femur measured from the apex of the left femoral head to the distal medial left femoral condyle.

Data Type

Numeric

Value Set

N/A

Units

cm



Left Tibia length

RadElement ID

RDE1183

Definition

Length of the left tibia measured from the medial left femoral condyle to the center of the left tibial plafond.

Data Type

Numeric

Value Set

N/A

Units

cm





Secondary Outputs


Right lower extremity angle at the knee

RadElement ID

RDE1184

Definition

The angle between the right femur and tibia

Data Type

Numeric

Value Set

N/A

Units

Degrees


Left lower extremity angle at the knee

RadElement ID

RDE1185

Definition

The angle between the left femur and tibia

Data Type

Numeric

Value Set

N/A

Units

Degrees



Pelvic Tilt

RadElement ID

RDE1186

Definition

Angle between the iliac crest to the horizontal

Data Type

Numeric

Value Set

N/A

Units

Degrees


Leg Length Discrepancy

RadElement ID

RDE1187

Definition

Absolute value of the difference between the lengths of the right and left lower extremities

Data Type

Numeric

Value Set

N/A

Units

cm



Leg Length Discrepancy Side

RadElement ID

RDE1188

Definition

The side of the leg that is longer

Data Type

Categorical

Value Set

  • right

  • left

  • the sides are equivalent in length

Units

N/A


Femur Length Discrepancy

RadElement ID

RDE1189

Definition

Absolute value of the difference between the lengths of the right and left femurs

Data Type

Numeric

Value Set

N/A

Units

cm



Femur Length Discrepancy Side

RadElement ID

RDE1190

Definition

The side of femur that is longer

Data Type

Categorical

Value Set

  • right

  • left

  • the sides are equivalent in length

Units

N/A


Tibia Length Discrepancy

RadElement ID

RDE1191

Definition

Absolute value of the difference between the lengths of the right and left tibias

Data Type

Numeric

Value Set

N/A

Units

cm



Tibia Length Discrepancy Side

RadElement ID

RDE1192

Definition

The side of the tibia that is longer

Data Type

Categorical

Value Set

  • right

  • left

  • the sides are equivalent in length

Units

N/A

Future Development Ideas


  • Status of physes (growth plates) - open, closing, closed

  • Bowing of femurs or tibiae

  • Rotation