Inter-observer and intra-observer reliability of mechanical axis alignment before and after total knee arthroplasty using long leg radiographs

Anneka Bowman, Meenalochani Shunmugam, Amy Watts, Donald Bramwell, Christopher Wilson, Jeganath Krishnan

Research output: Contribution to journalArticle

10 Citations (Scopus)

Abstract

Background: Long leg radiographs (LLRs) are commonly performed for assessment of mechanical alignment and operative planning in patients undergoing total knee arthroplasty (TKA). The aim of this study was to determine the inter- and intra-observer reliability of alignment measured by observers of different levels of experience. Methods: Forty patients on the waiting list for a TKA had pre- and post-operative standardised LLRs. We analysed the measurements of mechanical axis alignment between an orthopaedic surgeon, a senior orthopaedic registrar, a junior orthopaedic registrar, and a medical student. Reviewers performed blinded measurements on the same computer screen. These measurements were repeated three months later to assess intra-observer reliability. Furthermore high-resolution screens were compared with standard hospital computer screens to investigate whether monitoring quality influenced the accuracy of measurements of alignment. Results: Inter-observer reliability was high for pre-operative LLRs with an intra-class correlation (ICC) of >. 0.9 at all experience levels. Post-operative ICC was lowest between the surgeon and the medical student at 0.7. Intra-observer reliability was high at all experience levels. Larger deformities appeared to have exaggerated measurements for both pre- and post-operative images. There appeared to be no effect of the monitor size and quality on the accuracy of measurement. Conclusions: Long leg radiographs can be used to measure mechanical axis alignment with strong reliability across different levels of experience. This information is important for the evaluation of knee alignment measurements in current clinical practice, to assess severity of deformity and to accompany pre-operative planning and post-operative evaluation. Level of evidence: III.

Original languageEnglish
Pages (from-to)203-208
Number of pages6
JournalKnee
Volume23
Issue number2
DOIs
Publication statusPublished - 2016

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