Outerbridge classification of articular cartilage lesions

vigente

Grades one articular-cartilage lesion by direct visual and tactile morphology from softening through exposed subchondral bone. MRI use is an adaptation and must retain its modality and operational thresholds.

Índice de referência, não é suporte à decisão clínica. O RadCommons apresenta conteúdo de referência reescrito a partir de critérios publicados e com link para a fonte primária. Confira sempre a publicação primária vigente. Não é um dispositivo médico nem substitui o julgamento clínico. O radiologista responsável pelo laudo permanece o autor e o responsável.

Escala de categorias

0 I II III IV

As figuras e tabelas estão na fonte primária. Abrir a fonte. O RadCommons reescreve e cita, não reproduz figuras protegidas por direitos autorais.

Procedência e vigência

Órgão emissor: Outerbridge
Versão: 1961 original arthroscopic system; MRI adaptations must be labeled
Ano: 1961
Família: léxico
Tipo de lógica: flat
Modalidade: Arthroscopy, MRI
Fonte primária: The etiology of chondromalacia patellae · doi:10.1302/0301-620X.43B4.752
Última verificação: 2026-07-24
Última checagem: 2026-07-24

Lógica de decisão

Forma estruturada (flat). Uma futura calculadora a lê; as categorias abaixo são a superfície legível.

Retain the observation method. Apply the original diameter and bone-exposure boundaries only when supported, label MRI adaptations, and never turn this macroscopic grade into autonomous treatment or prognosis.

Mostrar a lógica estruturada (JSON)

{
  "categories": [
    {
      "outcome_code": "0",
      "state": "normal_intact_articular_cartilage",
      "role": "conventional_normal_state"
    },
    {
      "outcome_code": "I",
      "state": "softening_and_swelling",
      "surface": "may_appear_intact",
      "tactile_probe": "usually_required_for_confident_original_grade"
    },
    {
      "outcome_code": "II",
      "state": "partial_thickness_fragmentation_or_fissuring",
      "maximum_surface_diameter": "not_greater_than_0.5_inch_approximately_12.7_mm",
      "subchondral_bone": "not_reached_or_exposed"
    },
    {
      "outcome_code": "III",
      "state": "deep_fragmentation_or_fissuring",
      "maximum_surface_diameter": "greater_than_0.5_inch_approximately_12.7_mm",
      "subchondral_bone": "extends_down_to_but_does_not_expose"
    },
    {
      "outcome_code": "IV",
      "state": "full_thickness_cartilage_erosion",
      "subchondral_bone": "exposed",
      "size_rule": "bone_exposure_overrides_the_II_III_diameter_boundary"
    }
  ],
  "applicability": {
    "use_for": "Macroscopic severity description of one focal articular-cartilage lesion, originally by direct open or arthroscopic visualization and probing.",
    "classification_unit": "one_named_articular_surface_lesion",
    "required_inputs": [
      "joint_and_side",
      "articular_surface_and_location",
      "assessment_modality",
      "surface_integrity",
      "softening_or_swelling_when_directly_probed",
      "fissuring_or_fragmentation",
      "maximum_lesion_diameter",
      "subchondral_bone_exposure"
    ],
    "outside_scope": [
      "whole_joint_osteoarthritis_stage",
      "symptom_or_pain_source",
      "cartilage_repair_selection",
      "lesion_stability",
      "bone_marrow_or_meniscal_grading",
      "calibrated_prognosis"
    ]
  },
  "modality_and_quality_gate": {
    "original_reference_method": "Direct visualization with tactile probing. Grade I depends on softening and swelling that may not be visible without probe feedback.",
    "MRI_rule": "When grading MRI, label the result modified Outerbridge on MRI and state the sequence and image quality. MRI can depict contour, depth and bone exposure but cannot directly reproduce tactile softening.",
    "MRI_grade_I_guard": "Do not present Grade I as an original arthroscopic observation when only MRI signal alteration with an intact contour is available; return a low-confidence modified-MRI Grade I or describe the signal change without a definitive original grade.",
    "adequacy_rule": "If cartilage thickness, surface, lesion diameter or the cartilage-bone interface is not adequately shown, preserve the unresolved adjacent grades rather than force a label.",
    "joint_transfer_guard": "The original study concerned patellar chondromalacia. Later use across the knee and other joints is an adaptation; always retain joint, surface and method."
  },
  "original_classification_algorithm": [
    {
      "if": "intact_normal_cartilage_without_softening_swelling_fissure_or_erosion",
      "output_code": "0"
    },
    {
      "if": "softening_and_swelling_without_fragmentation_fissuring_or_bone_exposure",
      "output_code": "I"
    },
    {
      "if": "partial_thickness_fragmentation_or_fissuring_not_greater_than_12.7_mm_and_without_bone_exposure",
      "output_code": "II"
    },
    {
      "if": "deep_fragmentation_or_fissuring_greater_than_12.7_mm_reaching_toward_subchondral_bone_without_exposure",
      "output_code": "III"
    },
    {
      "if": "full_thickness_erosion_with_exposed_subchondral_bone",
      "output_code": "IV"
    }
  ],
  "measurement_and_boundary_rules": {
    "diameter_definition": "Use the maximum surface diameter of the chondral lesion. The original 0.5-inch boundary is approximately 12.7 mm; record the measured value and do not round solely to cross the boundary.",
    "II_versus_III": "The original distinction is lesion surface diameter around 0.5 inch together with depth toward subchondral bone, not a generic 50-percent cartilage-depth threshold.",
    "III_versus_IV": "Grade III reaches down to subchondral bone without exposing it; any unequivocal exposed subchondral bone is Grade IV regardless of lesion diameter.",
    "worst_component_rule": "For a heterogeneous lesion, report the maximum supported grade and also record the area or diameter of each full-thickness component rather than allowing a tiny Grade IV focus to erase lesion extent.",
    "multiple_lesion_rule": "Grade each anatomically separate lesion independently or explicitly state the aggregation rule; do not average Roman grades across surfaces."
  },
  "version_and_terminology_boundary": {
    "original_outerbridge": "The original macroscopic system uses Grades I-IV; Grade 0 is the conventional normal state used in later descriptions.",
    "modified_MRI_outerbridge": "Common MRI adaptations replace direct tactile findings with signal, contour and depth surrogates and may use percentage-depth bands. These thresholds are not identical to the original diameter-based II-III boundary and must be labeled as modified MRI criteria.",
    "ICRS_guard": "ICRS cartilage grades are a separate depth-based framework with subgrades. Do not translate ICRS and Outerbridge numbers one-to-one without an explicit validated mapping.",
    "no_ordinal_arithmetic": "Roman grades are categories. Do not average grades or treat a one-grade difference as a fixed biological interval."
  },
  "required_companion_report": [
    "joint_side_and_exact_articular_surface",
    "lesion_focal_or_diffuse_distribution",
    "maximum_surface_diameter_and_estimated_area",
    "cartilage_depth_or_full_thickness_component",
    "subchondral_bone_exposure_and_reactive_change",
    "unstable_flap_delamination_loose_body_or_opposing_kissing_lesion",
    "associated_meniscal_ligamentous_alignment_or_osteoarthritic_findings",
    "assessment_modality_and_whether_the_grade_is_original_arthroscopic_or_modified_MRI"
  ],
  "management_and_risk_context": {
    "management_rule": "Outerbridge grade does not prescribe debridement, marrow stimulation, grafting, cell implantation, osteotomy or arthroplasty. Treatment depends on symptoms, lesion size and containment, location, subchondral bone, alignment, meniscus, age, activity and the whole joint.",
    "risk_rule": "Some cohorts associate Grades III-IV with worse outcomes after specific arthroscopic procedures, but the system has no validated per-grade probability of pain, progression or treatment success.",
    "reliability_rule": "Published interobserver agreement is variable, especially around tactile Grade I and the II-III diameter boundary. Preserve uncertainty and the raw morphology."
  },
  "output_contract": [
    "joint_side_surface_and_location",
    "arthroscopy_open_visualization_or_modified_MRI",
    "technical_adequacy",
    "softening_swelling_surface_fissuring_fragmentation_and_depth",
    "maximum_diameter_in_mm_and_area_when_available",
    "subchondral_bone_exposure",
    "Outerbridge_0_I_II_III_IV_or_adjacent_grade_uncertainty",
    "associated_cartilage_and_joint_findings",
    "no_treatment_or_numeric_prognosis_from_grade_alone"
  ],
  "missing_input_behavior": [
    "If tactile probing is unavailable, do not assert original Grade I from imaging alone.",
    "If lesion diameter is unknown near the II-III boundary, return II-versus-III uncertainty and report depth and surface morphology.",
    "If the cartilage-bone interface is obscured, do not distinguish III from IV with confidence.",
    "If the MRI adaptation and its thresholds are unspecified, retain the observed morphology instead of silently applying an assumed modified scale."
  ],
  "interpretation_limits": [
    "Outerbridge is a macroscopic cartilage-lesion description, not a whole-joint osteoarthritis score or symptom attribution tool.",
    "The classification has inconsistent reader reliability and limited prognostic evidence and does not guide treatment by itself.",
    "MRI, arthroscopy and open inspection are not interchangeable observations; apparent grade changes across modalities may reflect method rather than biology."
  ],
  "supporting_sources": [
    {
      "role": "original_classification",
      "citation": "Outerbridge RE. J Bone Joint Surg Br. 1961;43-B:752-757",
      "doi": "10.1302/0301-620X.43B4.752",
      "pmid": "14038135"
    },
    {
      "role": "classification_review_and_limits",
      "citation": "Slattery and Kweon. Clin Orthop Relat Res. 2018;476:2101-2104",
      "doi": "10.1007/s11999.0000000000000255",
      "pmcid": "PMC6259817"
    },
    {
      "role": "MRI_arthroscopy_validation",
      "citation": "Potter et al. J Bone Joint Surg Am. 1998;80:1276-1284",
      "doi": "10.2106/00004623-199809000-00005",
      "pmid": "9759811"
    }
  ],
  "source_locator": "Outerbridge 1961, DOI 10.1302/0301-620X.43B4.752, original patellar chondromalacia series; Slattery and Kweon 2018, PMC6259817, History, Description, Validation, Limitations and Conclusions; Potter et al. 1998, PMID 9759811, prospective MRI-to-arthroscopy comparison."
}

Categorias num relance

Cat.	Significado	Conduta	Risco	Fonte
0	Grade 0, normal intact cartilage Conventional Grade 0: normal, intact articular cartilage at the named surface, without softening, swelling, fragmentation, fissuring, erosion or exposed subchondral bone. Grade 0 is the later conventional normal state; the original 1961 lesion grades were I-IV.	Document the inspected surface and assessment method. A Grade 0 surface requires no cartilage-lesion action from this scale, but it neither excludes another lesion elsewhere nor determines management of pain, instability, alignment, meniscal disease or another joint abnormality.	Grade 0 denotes no macroscopic lesion at the assessed surface, not a zero probability of symptoms, biochemical cartilage change or future degeneration. Outerbridge supplies no calibrated risk estimate for a normal-appearing surface.	okfonte Slattery and Kweon 2018, PMC6259817, Description and Fig. 1 define the conventional Grade 0 as normal cartilage; History explains that the original system was based on direct visualization and later expanded beyond the patella.
I	Grade I, softening and swelling Grade I: articular cartilage softening and swelling without the fragmentation or fissuring of Grade II and without subchondral-bone exposure. In the original macroscopic method, confident recognition commonly requires tactile feedback with a probe even when the surface looks intact.	Report the exact surface, extent and whether softening was directly probed. Grade I alone does not prescribe observation, chondroplasty or cartilage repair; management depends on symptoms and the lesion, patient and whole-joint context.	This is the earliest macroscopic lesion grade, but the classification does not assign a probability of pain, progression or treatment failure. MRI signal change cannot reproduce tactile softening and should be labeled as a modified-MRI assessment with limited confidence.	okfonte Slattery and Kweon 2018, PMC6259817, Description defines Grade I as softening and swelling and explains the need for tactile probe feedback; Limitations highlights difficulty and variable reliability for this grade and states that the system does not provide treatment guidance or clear prognosis.
II	Grade II, partial-thickness fissuring not greater than 0.5 inch Grade II: a partial-thickness cartilage defect with fragmentation or fissuring whose maximum surface diameter does not exceed 0.5 inch, approximately 12.7 mm, and which does not reach or expose subchondral bone. Preserve the measured diameter instead of rounding to force the threshold.	State location, maximum diameter, estimated area, depth, stability and associated joint findings. The Grade II label is descriptive and cannot by itself select debridement, marrow stimulation, grafting or rehabilitation.	Grade II is more extensive than softening alone but is not a validated patient-specific prognostic stratum. The II-III diameter boundary has limited reader reliability, so a near-threshold lesion should retain the measurement and adjacent-grade uncertainty.	okfonte Slattery and Kweon 2018, PMC6259817, Description defines the partial-thickness Grade II lesion and the 0.5-inch limit; Validation and Limitations discuss reader variability and difficulty separating Grades II and III by lesion size.
III	Grade III, deep fissuring greater than 0.5 inch without bone exposure Grade III: deep cartilage fragmentation or fissuring greater than 0.5 inch, approximately 12.7 mm, in maximum surface diameter, extending down toward subchondral bone but without unequivocal bone exposure. Bone exposure changes the grade to IV regardless of diameter.	Map the full lesion and any unstable flap, delamination or opposing lesion, then integrate symptoms, containment, subchondral bone, alignment, meniscus, age and activity in specialist planning. Grade III alone does not mandate a named procedure.	Some cohorts associate Grade III-IV lesions with worse outcomes after specific meniscal, hip or shoulder arthroscopic procedures, but those are context-dependent associations. Outerbridge provides no universal per-grade probability of progression, pain or failed treatment.	okfonte Slattery and Kweon 2018, PMC6259817, Description defines Grade III by fissuring over 0.5 inch extending down to subchondral bone; Validation summarizes procedure-specific outcome associations; Limitations rejects a clear prognostic or treatment rule.
IV	Grade IV, exposed subchondral bone Grade IV: full-thickness erosion of articular cartilage with exposed underlying subchondral bone. Exposure of bone is the defining feature and overrides the Grade II-III diameter boundary; record the size of the exposed component separately.	Report the exposed-bone area, lesion containment, location, opposing surface, reactive bone change and whole-joint mechanics. The severe morphology is clinically important, but the code alone cannot determine cartilage restoration, osteotomy, arthroplasty or conservative care.	Grade IV is the maximum macroscopic grade and procedure-specific cohorts group Grade III-IV with worse outcomes, yet the scale is not a calibrated prognosis. Symptoms and outcome depend on lesion extent, site, bone, alignment, meniscus, patient factors and selected treatment.	okfonte Slattery and Kweon 2018, PMC6259817, Description defines Grade IV by erosion exposing subchondral bone; Validation and Limitations describe limited prognostic associations, variable reliability and the absence of grade-directed treatment guidance.

Histórico de versões

Data	Evento	Detalhe	Situação
1998-09-01	revised	A prospective MRI-to-arthroscopy study operationalized a five-point Outerbridge assessment on specialized knee MRI; MRI use remains an adaptation of the macroscopic system. evidência	confirmado
1961-11-01	published	Outerbridge published the original direct-visualization grading framework for chondromalacia patellae. evidência	confirmado

Quickstart da APIGET /api/v1/systems/outerbridgeaberto

curl -s "https://radcommons.laudos.ai/api/v1/systems/outerbridge"

Ver documentação completa