As physiotherapists and rehabilitation professionals, we are continuously evolving our approach to align with patient-centered care and evidence-based practices. One of the critical tools in this shift has been the use of Patient-Reported Outcome Measures (PROMs)—especially in procedures like Total Knee Arthroplasty (TKA), where outcomes are not solely defined by surgical success, but also by the patient’s lived experience of function and quality of life.
Recently, I came across a comprehensive systematic review published in Bone & Joint Research (Wang et al., 2021), which evaluates PROMs used in TKA through the lens of updated COSMIN methodology. The study is titled:
“Patient-reported outcome measures used in patients undergoing total knee arthroplasty: a COSMIN systematic review.”
This review is a significant contribution to both clinical practice and research, offering clarity on which PROMs are psychometrically robust and which require further validation.
📌 Why This Review Matters
TKA is an elective surgery meant to restore function and relieve pain, yet dissatisfaction rates post-TKA hover around 10-20%. This disconnect is often due to a gap between clinical assessments and the patient’s perception of recovery. PROMs help bridge that gap by allowing patients to directly report their outcomes, shedding light on areas like function, pain, quality of life, and even joint awareness.
But here’s the catch: not all PROMs are created equal. Many are widely used, but few are rigorously validated for all relevant measurement properties. That’s where this COSMIN systematic review comes in.
🧠 Methodological Rigor
The authors screened over 5,000 articles and included 155 studies evaluating 34 PROMs used in TKA. Each instrument was assessed for nine measurement properties, including:
- Content validity
- Structural validity
- Internal consistency
- Reliability
- Measurement error
- Criterion validity
- Construct validity
- Responsiveness
- Cross-cultural validity
The updated COSMIN guidelines ensured a high level of methodological integrity, applying both qualitative synthesis and meta-analysis where applicable.
✅ PROMs Recommended for Use in TKA
After this rigorous assessment, nine PROMs were found to meet the minimum criteria for content validity and internal consistency, placing them in COSMIN’s Category A (recommended for use):
- Oxford Knee Score (OKS)
- OKS – Activity and Participation Questionnaire (OKS-APQ)
- KOOS – Physical Function Short Form (KOOS-PS)
- KOOS – 12-Item Short Form (KOOS-12)
- WOMAC – Total Knee Replacement Function Short Form (WOMAC-TKR)
- Lower Extremity Functional Scale (LEFS)
- Forgotten Joint Score (FJS)
- Patient’s Knee Implant Performance (PKIP)
- University of California Los Angeles (UCLA) Activity Score
Interestingly, subscales within larger tools were also validated for use independently:
- Pain and function subscales of WOMAC
- Pain, function, and QoL subscales of KOOS
⚠️ Gaps and Future Directions
One of the most striking findings is that none of the included PROMs were validated for all nine measurement properties. Specifically, issues were noted in:
- Cross-cultural validity
- Structural validity
- Measurement error reporting
This highlights a crucial research gap: while we may have PROMs that are “good enough” for certain uses, no instrument is comprehensive across the board. The study calls for further work to improve PROMs’ validity, especially in diverse populations and evolving clinical contexts.
💭 Reflections from a Rehabilitation Perspective
As a clinician-researcher engaged in both patient care and academic scholarship, this review has reinforced my commitment to using validated tools that reflect what matters most to patients. In my own work with musculoskeletal populations, especially those recovering from joint replacements, the incorporation of the FJS or OKS could provide deeper insight into patients’ real-world outcomes.
This COSMIN systematic review by Wang et al. (2021) is more than an academic exercise—it’s a practical guide for clinicians, educators, and researchers alike. It challenges us to move beyond conventionally used tools and adopt outcome measures that are truly meaningful, reliable, and patient-centered.
I highly recommend this paper to anyone working in orthopaedics, physiotherapy, sports medicine, or healthcare outcomes research.
📖 Full citation:
Wang Y, Yin M, Zhu S, Chen X, Zhou H, Qian W. Patient-reported outcome measures used in patients undergoing total knee arthroplasty: a COSMIN systematic review. Bone Joint Res. 2021;10(3):203–217. DOI: 10.1302/2046-3758.103.BJR-2020-0268.R1
Research in Motion 
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