Collins (2011) — Measures of knee function: International Knee Documentation Committee (IKDC) Subjective Knee Evaluation Form, Knee Injury and Osteoarthritis Outcome Score (KOOS), Knee Injury and Osteoarthritis Outcome Score Physical Function Short Form (KOOS-PS), Knee Outcome Survey Activities of Daily Living Scale (KOS-ADL), Lysholm Knee Scoring Scale, Oxford Knee Score (OKS), Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), Activity Rating Scale (ARS), and Tegner Activity Score (TAS).

Measures of Knee Function: International Knee Documentation Committee (ikdc) Subjective Knee Evaluation Form, Knee Injury and Osteoarthritis Outcome Score (koos), Knee Injury and Osteoarthritis Outcome Score Physical Function Short Form (koos-Ps), Knee Outcome Survey Activities of Daily Living Scale (kos-Adl), Lysholm Knee Scoring Scale, Oxford Knee Score (oks), Western Ontario and Mcmaster Universities Osteoarthritis Index (womac), Activity Rating Scale (ars), and Tegner Activity Score (tas).

·Arthritis Care Res (Hoboken)·2011·1,220 citations·Sports Medicine

Collins et al. systematically characterize nine patient-reported outcome measures for adult knee conditions — covering ligament injury, meniscal pathology, cartilage lesions, patellofemoral pain, and OA — evaluating each instrument's content, scoring, psychometric properties (reliability, validity, responsiveness), and practical usability for clinical and research settings.

Study Snapshot

Key Findings

Nine PROs were reviewed; the number of supporting psychometric studies ranged from 2–27 per instrument — more studies means greater certainty that reported properties reflect true performance
Three thresholds define whether a PRO is actually measuring what it claims:
Internal consistency: Cronbach's alpha ≥0.7
Test-retest reliability: ICC ≥0.8 for group comparisons, ≥0.9 for individual patients
Floor/ceiling effects: problematic when >15% of a cohort scores at an extreme
The Lysholm scale fails the internal consistency threshold across knee conditions and was designed for clinician administration — its widespread use as a self-report tool introduces systematic bias that undermines individual-level interpretation
The KOOS sport/recreation subscale shows floor effects in 16–73.3% of patients with severe OA awaiting TKR, meaning it cannot discriminate impairment levels in the population UKA targets; MCID and PASS remain unreported for KOOS across all populations
WOMAC is the only instrument with a published PASS for knee OA — 31.0 (95% CI 29.4–32.9) on the function subscale — making it the default when a treatment success threshold must be defined, despite its licensing cost relative to freely available alternatives

Board PearlWOMAC is the only knee PRO with a published treatment-success threshold (PASS = 31.0 on function subscale) — use it when defining acceptable outcomes in knee OA research.

Clinical Relevance

Essential reference when selecting appropriate outcome measures for knee research protocols or systematic tracking of patient-reported outcomes in clinical practice.

Reference

Measures of Knee Function: International Knee Documentation Committee (ikdc) Subjective Knee Evaluation Form, Knee Injury and Osteoarthritis Outcome Score (koos), Knee Injury and Osteoarthritis Outcome Score Physical Function Short Form (koos-Ps), Knee Outcome Survey Activities of Daily Living Scale (kos-Adl), Lysholm Knee Scoring Scale, Oxford Knee Score (oks), Western Ontario and Mcmaster Universities Osteoarthritis Index (womac), Activity Rating Scale (ars), and Tegner Activity Score (tas).

Collins, Roos, et al.·Arthritis Care Res (Hoboken)·2011·1,220 citations·Sports Medicine

Study Snapshot

Key Findings

Clinical Relevance

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