| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 4077185 | The Knee | 2016 | 5 Pages |
•Long-leg radiographs (LLR) taken after total knee arthroplasty were studied.•Six surgeons performed measurements on LLR to obtain inter-observer reliability.•Validity of LLR measurements were compared to 3D-CT scan, using Bland–Altman plots.•Measurements on LLR show moderate to good reliability.•Measurements on LLR show good validity when compared to 3D CT-scan.
BackgroundLong-leg radiographs (LLR) are often used in orthopaedics to assess limb alignment in patients undergoing total knee arthroplasty (TKA). However, there are still concerns about the adequacy of measurements performed on LLR. We assessed the reliability and validity of measurements on LLR using three-dimensional computed tomography (3D CT)-scan as a gold standard.MethodsSix different surgeons measured the mechanical axis and position of the femoral and tibial components individually on 24 LLR. Intraclass correlation coefficients (ICC) were calculated to obtain reliability and Bland–Altman plots were constructed to assess agreement between measurements on LLR and measurements on 3D CT-scan.ResultsICC agreement for the six observer measurements on LLR was 0.70 for the femoral component and 0.80 for the tibial component.The mean difference between measurements performed on LLR and 3D CT-scan was 0.3° for the femoral component and − 1.1° for the tibial component. Variation of the difference between LLR and 3D CT-scan for the femoral component was 1.1° and 0.9° for the tibial component. 95% of the differences between measurements performed on LLR and 3D CT-scan were between − 1.9 and 2.4° (femoral component) and between − 2.9 and 0.7 (tibial component).ConclusionMeasurements on LLR show moderate to good reliability and, when compared to 3D CT-scan, show good validity.Clinical trial registration number: institutional review board Atrium-Orbis-Zuyd, number: 11-T-15.Level of EvidenceProspective cohort study, Level II.
