knee
Enable an AI agent to recognise a knee, record its structural and functional state, and distinguish supported actions from actions requiring further assessment or authority.
Research draft, second pass
A second pass drafted this model: the structure a model of this thing needs, and what is known about it in the world. The line under this one says how the second half was obtained - researched against sources, or recalled without web access, in which case nothing here was read anywhere and every claim is a lead to verify. Unreviewed either way.
Researched by: Codex + Grok
Purpose and description
Enable an AI agent to recognise a knee, record its structural and functional state, and distinguish supported actions from actions requiring further assessment or authority.
The knee is the compound synovial modified-hinge joint of the lower limb in which the femoral condyles articulate with the tibial plateaus (the tibiofemoral joint, with interposed menisci) and the patella articulates with the femoral trochlea (the patellofemoral joint), transmitting load and permitting flexion, extension and limited rotation under ligamentous constraint.
It can be Associate symptoms, examination records, and imaging with the correct knee and local structure.; Compare knee motion, swelling, symptoms, and task performance across dated assessments.; Identify missing or conflicting evidence before attributing symptoms to a particular knee structure.; Check a proposed knee-related activity against recorded restrictions and assessment requirements.; Link knee procedures and implants to subsequent structural and functional observations.; Flag recorded concerns for qualified review using an applicable clinical protocol..
Distinguishing features
Locate the joint complex between the distal femur and proximal tibia, with the patella associated anteriorly; a reference to the leg alone does not identify a knee.
Determine whether a record concerns the knee complex or only the patella; the patella is a component, not the entire knee.
Distinguish the patellofemoral articulation from the tibiofemoral articulation while retaining both within the same knee identity.
Check whether 'knee pain' identifies only a reported symptom location or also establishes a local structural condition; the former does not establish the latter.
Distinguish the anatomical knee from a knee replacement device; an implanted knee retains anatomical identity while relating to a separate device.
Scope
+ Left or right knee identity, anatomical boundaries, and relationship to its person and limb
+ Tibiofemoral and patellofemoral articulations and their local structural condition
+ Menisci, ligaments, capsule, and the knee-related portions of the extensor mechanism
+ Knee movement, stability, loading, and contribution to specific activities
+ Local symptoms, examination findings, investigations, and changes over time
+ Knee-specific procedures, implants, restrictions, and assessment needs
- The person's complete health history and systemic disease models
- Hip, ankle, and whole-limb conditions beyond their recorded effects on the knee
- Complete models of the femur, tibia, fibula, muscles, nerves, or blood vessels
- Whole-person gait, athletic performance, and rehabilitation programme management
- Implant product specifications, manufacturing records, and device inventory
- Independent models of injuries or diseases that may affect multiple anatomical sites
Characteristics
- Laterality
- left | right | unresolved Prevents observations, imaging, and actions from being assigned to the opposite knee.
- Anatomical configuration
- Recorded native, altered, reconstructed, or replaced structures, with unknowns explicit Determines which structures are present and how observations should be interpreted.
- Affected articulation or compartment
- medial tibiofemoral | lateral tibiofemoral | patellofemoral | multiple | unlocalised Localises findings without treating every knee condition as affecting the entire complex.
- Flexion and extension range
- degrees, with angle convention, active or passive method, position, and date Makes motion restriction and change interpretable and comparable.
- Stability assessment
- Direction, named assessment, result or grade, examiner, and assessment conditions Separates measured laxity from reported giving way and preserves the basis of the assessment.
- Pain pattern
- Location, onset, duration, provoking activity, rest symptoms, and named severity scale Connects symptoms to circumstances without converting symptoms into a diagnosis.
- Swelling and effusion
- Observed location, onset, assessment method, and present | absent | uncertain result Distinguishes joint fluid findings from other forms of local swelling.
- Task-specific function
- Task, assistance, tolerance, symptoms, and observed or reported performance Shows what the knee permits during activities such as stairs, kneeling, or rising from a chair.
- Local tissue condition
- Named structure, finding, assessment method, date, and certainty Keeps evidence about cartilage, menisci, ligaments, and tendons anatomically specific.
- Intervention and restriction relationship
- Linked procedure, implant, clinical instruction, responsible professional, and effective dates Supports action decisions using the knee's actual treatment history and current instructions.
Also called
Where this came from
wikidata · CC0 1.0
Also registered as vr.tr.knee-artifact
Drafted structure
Bundle to layer to finding to question, as the second pass will find it: 6 bundles · 11 layers · 18 findings · 28 questions.
Knee identity and boundaries Establish which knee is represented and which anatomical structures its records concern.
Laterality mistakes and confusion between a joint, a component, and a symptom location undermine every subsequent decision.
Person, limb, and side
Bind the knee to its anatomical owner and side.
Identified knee
Record the person, limb, and laterality, including unresolved or conflicting identification.
- Which person's knee is this, and what establishes its left or right side? definition
- Do examination notes, images, and procedure records agree on the knee's identity? provenance
Joint complex boundary
Separate the knee complex from individual components and neighbouring anatomy.
Anatomical coverage
Identify the articulations and local supporting structures covered by each observation.
- Does this observation concern the tibiofemoral articulation, patellofemoral articulation, supporting tissues, or an unlocalised knee region? definition
- Where should this record link to a neighbouring bone, tendon, joint, or limb model instead of extending the knee's ownership? boundary
Articulations and supporting tissues Represent the knee's articular surfaces, menisci, stabilising structures, and extensor mechanism.
Different knee structures can produce overlapping symptoms while requiring distinct evidence and action constraints.
Articular and meniscal condition
Localise observations to joint compartments, cartilage, and menisci.
Surface and meniscus findings
Record compartment-specific structural observations without assuming that an imaging finding explains symptoms.
- Which articular surface or meniscus is described, and what condition was observed? definition
- Which examination, imaging study, or procedure supports the observation, and when was it obtained? provenance
Stabilisers and extensor mechanism
Represent knee ligaments, capsule, and the structures involved in active extension.
Supporting tissue integrity
Record structure-specific integrity, prior repair or reconstruction, and the limits of available evidence.
- Which ligament, capsular structure, or extensor mechanism component is intact, altered, repaired, or uncertain? definition
- What evidence supports that assessment, and does it describe tissue appearance, mechanical function, or both? provenance
Motion, stability, and load Describe how the knee moves and behaves under specified assessment and activity conditions.
Structural descriptions alone do not establish available movement, stability, or functional capacity.
Range and stability assessment
Capture reproducible motion and stability observations.
Measured knee mechanics
Record flexion, extension, and assessed laxity with methods and conditions.
- What active and passive flexion and extension were measured, using which angle convention and position? measurement
- What directional stability assessments were performed, and what results, symptoms, or assessment limitations were recorded? measurement
Loaded task performance
Connect knee behaviour to activities and external support.
Activity-dependent capacity
Record performance during walking, stairs, chair rise, squatting, kneeling, or other relevant tasks.
- During which task, load, and assistance conditions were pain, giving way, catching, or movement limitation observed or reported? measurement
- Which task limitations are attributed to the knee, and which may involve the hip, ankle, balance, or another condition? boundary
Symptoms and state assessment Track local symptoms, examination signs, temporal changes, and the strength of proposed explanations.
A knee model must distinguish what a person experiences, what an assessor observes, and what has actually been established.
Symptom location and course
Describe pain, swelling, stiffness, and mechanical symptoms over time.
Dated knee symptom pattern
Record onset, location, triggers, duration, and change while preserving the reporter's meaning.
- Where and when do pain, swelling, or stiffness occur, and how have they changed relative to an injury, procedure, or activity? measurement
- When someone reports locking or giving way, what precisely happened, and was it reported, witnessed, or reproduced during assessment? provenance
Evidence and clinical interpretation
Keep observed signs, investigation results, and clinical conclusions distinguishable.
Supported state judgement
Link any conclusion about the knee's state to dated evidence and explicitly retain unresolved explanations.
- Which local signs and investigation findings support the recorded interpretation, and who made that interpretation? provenance
- What remains unresolved about a local knee cause, a referred symptom, or a systemic contributor? boundary
Interventions and action constraints Connect prior knee interventions and current clinical instructions to proposed actions.
Repairs, reconstructions, replacements, and current restrictions can change how knee findings should guide activity and assessment.
Altered anatomy and procedure history
Record procedures that changed the knee and link any implanted components.
Post-intervention configuration
Identify treated structures, procedure dates, and resulting anatomical changes without substituting a device record for the knee.
- Which knee structures were repaired, reconstructed, removed, or replaced, and on what dates? provenance
- Which details describe the anatomical knee, and which belong in linked procedure or implant records? boundary
Current permissions and review needs
Represent applicable restrictions, their authority, and conditions requiring further assessment.
Supported next action
Evaluate proposed knee-related actions against documented instructions, evidence gaps, and applicable review protocols.
- What current instructions govern weight bearing, knee motion, bracing, or activity, and who issued them for what period? action
- Does the proposed action require additional assessment or qualified review under the applicable protocol, given this knee's recorded condition? action
Evidence and external alignment What the world already says about this thing, gathered so the model can be checked against it.
A model that cannot be lined up against existing standards, identifiers and practice cannot be adopted by anyone who already uses them.
Reported evidence
Findings from the breadth pass, kept separate from the structural claims.
Kinds and varieties
Reported by the breadth pass; each item needs checking against its source before it becomes normative.
- tibiofemoral joint (medial and lateral condylar articulations)
- patellofemoral joint
- medial tibiofemoral compartment
- lateral tibiofemoral compartment
- native (unreplaced) knee
- total knee replacement (total knee arthroplasty)
- unicompartmental / partial knee replacement
- laterality: right knee versus left knee
- Which of these kinds and varieties hold for the sense of knee this model covers, and on what evidence? provenance
Identifiers and schemes
Reported by the breadth pass; each item needs checking against its source before it becomes normative.
- Terminologia Anatomica / Latin - articulatio genus (also articulatio genu); articulatio patellofemoralis - Preferred anatomical names used in TA-aligned teaching sources; numeric TA98/TA2 codes for the joint as a whole were not retrieved in this pass.
- SNOMED CT - Knee joint structure (body structure); Entire knee joint (body structure) - Preferred terms from CISMeF mappings; numeric SCTIDs were not retrieved.
- FMA - Knee joint - Entity name from CISMeF; numeric FMAID not retrieved.
- MeSH - Knee joint - Descriptor name from CISMeF; MeSH Unique ID not retrieved.
- UBERON - knee joint - Concept name from CISMeF; numeric UBERON ID not retrieved.
- ICD-11 - Knee joint (anatomy extension code) - Used to locate findings and procedures; the exact extension-code string was not retrieved.
- ICD-10-CM - M17* (osteoarthritis of knee); S83* (dislocation, sprain and strain of joints and ligaments of knee); M21.06* / M21.26* (valgus / flexion deformity of knee) - Disease, injury and deformity codes that take the knee as the site, with right/left/unspecified laterality in ICD-10-CM.
- LOINC - 100165-0 - Knee range of motion, quantitative, in degrees; a measurement of the joint rather than an identifier of the organ.
- NCIt - Knee Joint - Concept name from CISMeF.
- RadLex - knee joint (constitutional part of knee) - RID code not retrieved; CISMeF treats the joint as a part of the knee region.
- Which of these identifiers and schemes hold for the sense of knee this model covers, and on what evidence? provenance
Standards and regulation
Reported by the breadth pass; each item needs checking against its source before it becomes normative.
- ISO 21536:2023 - Non-active surgical implants - Joint replacement implants - Specific requirements for knee-joint replacement implants (International Organization for Standardization, ISO/TC 150/SC 4).
- EN ISO 21536:2024 - same title, European adoption of ISO 21536:2023 (CEN).
- ISO 21534 and ISO 7207-1 - general joint-replacement and knee-implant vocabulary referenced by ISO 21536 (International Organization for Standardization).
- 2019 American College of Rheumatology / Arthritis Foundation Guideline for the Management of Osteoarthritis of the Hand, Hip, and Knee (ACR and Arthritis Foundation).
- Surgical Management of Osteoarthritis of the Knee, clinical practice guideline (American Academy of Orthopaedic Surgeons).
- ICD-10-CM (National Center for Health Statistics / CMS) for laterality-specific coding of knee disease, injury and deformity in US records.
- Terminologia Anatomica (FIPAT / IFAA) for the official anatomical names of the joint and its parts.
- Which of these standards and regulation hold for the sense of knee this model covers, and on what evidence? provenance
Real-world use
Reported by the breadth pass; each item needs checking against its source before it becomes normative.
- Primary load-bearing joint of gait, standing, sitting, stair climbing and squatting; examined clinically for effusion, alignment, ligament laxity and range of motion.
- Imaged with standing radiographs and MRI as the default work-up for pain, locking, instability and osteoarthritis.
- Common site of sports injury (ACL, meniscus, collateral ligaments) and of arthroscopic repair or reconstruction.
- End-stage tibiofemoral osteoarthritis is treated by total or unicompartmental knee arthroplasty under ISO 21536-class implants; patellofemoral pain is usually managed with exercise, taping or orthoses rather than surgery.
- Outcome is scored with instruments such as KOOS and the Knee Society Score, which include LOINC-coded range-of-motion items.
- Which of these real-world use hold for the sense of knee this model covers, and on what evidence? provenance
Typical measurements
Reported by the breadth pass; each item needs checking against its source before it becomes normative.
- knee flexion range of motion - 120 to 150 (from 0° extension; soft-tissue bulk and age dependent) - degree
- knee extension, including physiologic hyperextension - 0; some people 5 to 10 of hyperextension; beyond about 10 is often treated as genu recurvatum - degree
- internal (medial) rotation with the knee flexed - about 10 - degree
- external (lateral) rotation with the knee flexed - about 10 active to about 30; up to about 60 reported as passive - degree
- patellar articular-cartilage thickness (adult, central) - up to about 6 at peak (around age 30) - millimetre
- patellar articular surface area (adult) - about 12 - square centimetre
- Which of these typical measurements hold for the sense of knee this model covers, and on what evidence? provenance
Failure modes and hazards
Reported by the breadth pass; each item needs checking against its source before it becomes normative.
- Knee osteoarthritis (gonarthrosis): activity-related pain, stiffness under 30 minutes, joint-space loss; estimated 654 million people worldwide; may progress to arthroplasty.
- Meniscal tear: traumatic (often under 40, twisting) or degenerative (often with OA over 40); about 12% of adults; displaced bucket-handle tears can lock the joint.
- Cruciate or collateral ligament rupture or sprain (especially ACL), producing instability, giving-way and secondary meniscal or chondral damage.
- Patellofemoral pain: anterior pain in active people under 40; lifetime prevalence about 25%; squat-related pain is sensitive but not specific.
- Alignment failure: genu varum, genu valgum, flexion contracture, genu recurvatum (hyperextension beyond about 10°).
- Intra-articular fracture (tibial plateau, distal femur, patella), dislocation, haemarthrosis, bursitis and septic arthritis.
- After replacement: implant wear, loosening, infection, stiffness, instability and the higher rate of serious adverse events seen with total knee replacement versus continued non-surgical care.
- Which of these failure modes and hazards hold for the sense of knee this model covers, and on what evidence? provenance
Regional variation
Reported by the breadth pass; each item needs checking against its source before it becomes normative.
- Clinical and ICD language: English 'osteoarthritis of the knee' versus 'gonarthrosis' / 'gonarthrose' in ICD-derived European usage.
- Nerve and ligament English: 'common peroneal' remains common in radiology; TA-aligned sources prefer 'common fibular'.
- US ICD-10-CM requires right/left/unspecified laterality on knee OA and deformity codes (e.g. M17.11 versus M17.12); WHO ICD-10 often does not.
- Implant practice splits total versus unicompartmental replacement and cruciate-retaining versus posterior-stabilized designs; ISO 21536 now defines 'maximum claimed flexion' because demanded flexion is not uniform across patients and markets.
- Which of these regional variation hold for the sense of knee this model covers, and on what evidence? provenance
Neighbouring kinds and how to tell them apart
Reported by the breadth pass; each item needs checking against its source before it becomes normative.
- knee region (regio genus) - The region is a body-location class (skin, bursae, popliteal fossa, extra-articular fat); the knee joint is the synovial articulations. Test: presence of articular surfaces and a joint cavity, not merely a topographic landmark.
- proximal tibiofibular joint - A separate synovial joint at the fibular head, not one of the three knee compartments. Test: the articulation is fibular head to lateral tibial condyle, outside the tibiofemoral meniscal cavity.
- patella (kneecap) - A sesamoid bone in the quadriceps-patellar tendon, not the joint. Test: bone continuity and sesamoid position versus the two synovial articulations that use its posterior surface.
- hip joint - Proximal neighbour whose pain is often referred to the knee. Test: groin or greater-trochanter pain and hip rotation reproducing symptoms, with a quiet knee examination and imaging.
- temporomandibular joint - Another diarthrodial hinge with a fibrocartilage disc, sometimes analogized to the knee; different bones, load and surgical frequency. Test: mandible-temporal articulation versus femur-tibia-patella.
- Which of these neighbouring kinds and how to tell them apart hold for the sense of knee this model covers, and on what evidence? provenance
Sources
- Knee joint: anatomy, ligaments and movements - Joint type, bones, tibiofemoral versus patellofemoral articulations, ligaments and menisci, innervation, blood supply, and named movements.
- Knee joint - Modified-hinge classification, largest synovial joint, compartment geometry, menisci, and published flexion/extension/rotation ranges used in imaging.
- In brief: How does the knee work? - Three-compartment model, typical flexion to about 150°, and rotation of a flexed knee (about 10° inward, 30° outward).
- ISO 21536:2023 Non-active surgical implants - Joint replacement implants - Specific requirements for knee-joint replacement implants - That total and partial knee replacements, with or without patellofemoral replacement, are a regulated implant class with specified performance, materials and test methods.
- knee joint - Cross-walk of the joint into SNOMED CT, FMA, MeSH, UBERON, NCIt, ICD-11 extension, ICF, RadLex and related anatomy codes.
- LOINC 100165-0 Knee range of motion - A standard observation identifier for quantitative knee range of motion in degrees, including use in Knee Society Score panels.
- Evaluation and Treatment of Knee Pain: A Review - Population-scale osteoarthritis burden, patellofemoral pain and meniscal-tear prevalence, and first-line versus surgical management.
- 2019 American College of Rheumatology/Arthritis Foundation Guideline for the Management of Osteoarthritis of the Hand, Hip, and Knee - Joint-specific OA treatment recommendations, including tibiofemoral versus patellofemoral bracing.
- ICD-10-CM order file (2022) - M17 Osteoarthritis of knee and related deformity codes - US clinical coding of knee osteoarthritis and knee deformity with mandatory laterality.
What the second pass must settle
- Does vr.tr.knee cover human knees only, or must species-specific knee anatomy and terminology be represented?
- What precise regional boundary should govern ownership of bursae, the proximal tibiofibular joint, the popliteal region, and adjacent tendon segments?
- Which established Vercy models already own anatomical joints, knee disorders, procedures, and implants, and how should this entry link to them?
- Which validated assessment methods, grading systems, and measurement conventions should be supported for different ages and clinical contexts?
- Which authoritative clinical protocols should govern review triggers and action constraints, including after repair, reconstruction, or replacement?