Classify each hip only from a valid standard plane and return the most specific supported code. Parent codes preserve compatibility and make missing subtype inputs explicit instead of turning uncertainty into a false Ia/Ib, IIa+/IIa-, IIc stability, or IIIa/IIIb assignment.
{
"categories": [
{
"outcome_code": "I",
"state": "mature_parent_type",
"alpha_deg": ">=60",
"subtype_when_beta_available": [
"Ia",
"Ib"
]
},
{
"outcome_code": "Ia",
"state": "mature",
"alpha_deg": ">=60",
"beta_deg": "<=55",
"bony_roof": "good",
"bony_rim": "angular",
"cartilage_roof": "covers_femoral_head"
},
{
"outcome_code": "Ib",
"state": "mature",
"alpha_deg": ">=60",
"beta_deg": ">55",
"bony_roof": "good",
"bony_rim": "blunt_or_slightly_rounded",
"cartilage_roof": "covers_femoral_head"
},
{
"outcome_code": "IIa",
"state": "physiologically_immature_parent_type",
"alpha_deg": "50-59",
"chronological_age_weeks": "0-12",
"subtype_status": "not_assigned_before_week_6_or_age_curve_unavailable"
},
{
"outcome_code": "IIa+",
"state": "physiologically_immature_with_age_appropriate_maturation",
"alpha_deg": "50-59",
"chronological_age_weeks": "6-12",
"maturation_curve_position": "at_or_above_minimum_linear_curve_to_alpha_60_by_week_12"
},
{
"outcome_code": "IIa-",
"state": "physiologically_immature_with_maturational_deficit",
"alpha_deg": "50-59",
"chronological_age_weeks": "6-12",
"maturation_curve_position": "below_minimum_linear_curve_to_alpha_60_by_week_12"
},
{
"outcome_code": "IIb",
"state": "delayed_ossification_or_dysplastic_for_age",
"alpha_deg": "50-59",
"chronological_age_weeks": ">12",
"bony_roof": "deficient",
"bony_rim": "rounded",
"cartilage_roof": "covers_femoral_head"
},
{
"outcome_code": "IIc",
"state": "critical_centered_parent_type",
"alpha_deg": "43-49",
"resting_beta_deg": "<=77",
"stress_status": "not_available_or_not_valid"
},
{
"outcome_code": "IIc-stable",
"state": "critical_centered_stable",
"alpha_deg": "43-49",
"resting_beta_deg": "<=77",
"stress_behavior": "remains_centered_and_does_not_convert_to_type_D"
},
{
"outcome_code": "IIc-unstable",
"state": "critical_centered_at_rest_but_pathologically_unstable",
"alpha_deg": "43-49",
"resting_beta_deg": "<=77",
"stress_behavior": "converts_to_type_D_with_beta_above_77"
},
{
"outcome_code": "D",
"state": "decentering_at_rest",
"alpha_deg": "43-49",
"resting_beta_deg": ">77",
"cartilage_roof": "displaced"
},
{
"outcome_code": "III",
"state": "decentered_parent_type",
"alpha_deg": "<43",
"cartilage_roof": "pressed_cranially",
"subtype_when_cartilage_echogenicity_available": [
"IIIa",
"IIIb"
]
},
{
"outcome_code": "IIIa",
"state": "decentered_without_structural_cartilage_alteration",
"alpha_deg": "<43",
"cartilage_roof": "pressed_cranially_and_hypoechoic_or_without_internal_echoes"
},
{
"outcome_code": "IIIb",
"state": "decentered_with_structural_cartilage_alteration",
"alpha_deg": "<43",
"cartilage_roof": "pressed_cranially_and_echogenic"
},
{
"outcome_code": "IV",
"state": "severely_decentered",
"alpha_deg": "<43",
"cartilage_roof": "pressed_caudally",
"proximal_perichondrium": "horizontal_or_dips_caudally"
}
],
"applicability": {
"use_for": "Morphologic classification of each infant hip on a technically valid Graf ultrasound examination.",
"classification_unit": "one_hip_at_one_examination",
"required_inputs": [
"side",
"chronological_age_in_weeks",
"standard_plane_images",
"bony_roof_morphology",
"bony_rim_morphology",
"cartilage_roof_position",
"alpha_angle_deg",
"beta_angle_deg"
],
"conditional_inputs": [
"stress_examination_for_type_IIc_stability",
"cartilage_roof_echogenicity_for_type_III_subtyping",
"gestational_age_for_management_context_in_preterm_infants"
],
"outside_scope": [
"radiographic_DDH_classification_after_ossification",
"clinical_instability_without_valid_ultrasound",
"treatment_selection_without_age_stability_and_orthopaedic_assessment"
]
},
"image_quality_gate": {
"required_identification": [
"lower_limb_of_ilium",
"mid_acetabular_standard_plane",
"labrum",
"chondro_osseous_junction",
"straight_iliac_contour"
],
"minimum_documentation": "Two standard-plane images of each hip, with side, patient age, examination date, alpha and beta measurement lines, and morphology visible.",
"failure_rule": "If the standard plane or required landmarks are not demonstrated, do not measure or assign a definitive Graf type; request repeat technically adequate imaging.",
"anti_tilt_rule": "Probe tilt can make a normal hip appear abnormal. Reject an image with a missing lower limb, non-straight iliac reference, or other standard-plane failure rather than classifying the artifact."
},
"measurement_model": {
"alpha_angle": "Angle between the iliac baseline and the bony-roof line; it establishes the main type.",
"beta_angle": "Angle between the iliac baseline and the cartilage-roof line through the labrum; it refines Type I and separates centered IIc from decentering D.",
"morphology_rule": "Angles never replace the qualitative description of the bony roof, bony rim, cartilage roof and femoral-head centering.",
"borderline_rule": "Preserve the measured angles and acquisition quality. Do not round a borderline or low-confidence measurement solely to force a category."
},
"age_dependent_type_IIa": {
"before_week_6": "Use parent code IIa; Graf advises against IIa+/IIa- differentiation before week 6 because measurement imprecision can exceed the maturational difference.",
"weeks_6_to_12": "Compare alpha with the Graf sonometer or its minimum linear maturation curve from alpha 50 at birth to alpha 60 at week 12.",
"curve_formula_for_unrounded_age": "minimum_alpha_deg = 50 + (10 * chronological_age_weeks / 12)",
"example_at_week_6": {
"IIa_plus": "alpha_55_or_more",
"IIa_minus": "alpha_below_55_but_at_least_50"
},
"after_week_12": "An alpha angle of 50-59 is IIb, not IIa.",
"preterm_rule": "Assign the morphologic type using chronological age; interpret management timing in the context of gestational age and specialist assessment."
},
"stability_model": {
"resting_position_controls_base_type": true,
"IIc_stress_rule": "A resting IIc hip that becomes D under pressure is IIc-unstable; if it remains centered it is IIc-stable.",
"physiological_elasticity_rule": "Labral or capsular movement in a hip with adequate bony coverage is elasticity and must not be mislabeled pathological instability.",
"decentered_rule": "D, III and IV are already decentered at rest and are intrinsically unstable; do not rename III as IV solely because stress increases displacement.",
"terminology_guard": "Use D rather than IId. In the Graf model every Type II hip is centered; D is the distinct decentering category."
},
"classification_sequence": [
"validate_standard_plane_and_side",
"describe_bony_roof_bony_rim_cartilage_roof_and_centering",
"measure_alpha_and_beta_without_forced_rounding",
"assign_main_type_from_alpha_and_morphology",
"apply_chronological_age_to_the_50_to_59_degree_range",
"apply_beta_to_Type_I_and_to_IIc_versus_D",
"if_resting_IIc_apply_valid_stress_assessment_for_stable_or_unstable_subtype",
"if_Type_III_apply_cartilage_echogenicity_for_IIIa_or_IIIb"
],
"management_context": {
"stable_morphologic_abnormality": "The AAOS guideline supports observation without a brace as an option for a clinically stable hip with morphologic ultrasound abnormalities, based on limited evidence; this is not a type-only mandate.",
"positive_instability_examination": "The AAOS guideline supports either immediate or delayed brace treatment as options, based on limited evidence, with serial examination and age-appropriate imaging during treatment.",
"safety_rule": "The Graf code informs urgency and follow-up but does not independently select a brace, reduction method, operation, or surveillance interval."
},
"output_contract": [
"right_or_left_hip",
"chronological_age_and_prematurity_context",
"technical_adequacy_and_standard_plane",
"alpha_and_beta_angles_in_degrees",
"bony_roof_bony_rim_and_cartilage_roof_morphology",
"femoral_head_centering_at_rest",
"stress_result_when_used",
"most_specific_supported_Graf_code",
"explicit_parent_code_when_subtype_input_is_missing",
"orthopaedic_follow_up_flag_without_autonomous_treatment"
],
"missing_input_behavior": [
"If age is unknown in an alpha 50-59 hip, do not choose IIa or IIb; report the measured Type II range and request age.",
"If beta is unavailable in a mature hip, return parent I rather than inventing Ia or Ib.",
"If stress imaging is absent for a resting IIc hip, return parent IIc and do not infer stable or unstable from the static image.",
"If cartilage-roof echogenicity is not documented in Type III, return parent III rather than guessing IIIa or IIIb.",
"If image quality is invalid, return no definitive type even when an angle was supplied."
],
"interpretation_limits": [
"Graf is a morphology and maturation classification, not a patient-specific prognosis or a substitute for the clinical instability examination.",
"Do not translate the sequence of labels into a numeric risk percentage or prescribe treatment without age, stability, examination findings and pediatric orthopaedic context.",
"Do not apply the infant ultrasound thresholds to radiographs, CT, MRI, or an older child outside the validated sonographic setting."
],
"source_locator": "Graf, J Pediatr Orthop 1984;4:735-740, PMID 6392336, DOI 10.1097/01241398-198411000-00015; Graf, Hip Sonography, 2006, Table 6.1 and Chapters 7-9 for standard plane, sonometer, IIa maturation, IIc stress stability and III subtypes; AAOS DDH guideline 2014, Summary recommendations on stable morphologic abnormalities, clinical instability and monitoring."
}