CT measures of femoral and tibial version and rotational position of femoral and tibial components of knee replacements: limitations in reliability and suitability for routine clinical practice

Abstract

Objectives Rotational malalignment of knee replacements as measured on CT is understood to be associated with poor outcomes. The aim of this study is to measure the inter-rater and intra-rater reliability of measures of femoral and tibial version in the native arthritic knee and postoperative TKR component position using CT. Methods Eighty patients underwent CT of the knee before and after total knee replacement. Preoperative femoral and tibial version and component rotation were independently measured by two musculoskeletal radiologists. Results Mean differences between and within raters were small (< 1.6°). Maximum 95% limits of agreement for inter-rater and intra-rater comparisons were 8.1° and 7.6° for preoperative femoral version, 9.0° and 7.9° for postoperative femoral rotation, 26.0° and 20.5° for preoperative tibial version, and 24.9° and 23.6° for postoperative tibial rotation respectively. Postoperative ICCs varied from 0.68 to 0.81 (lower 95% CI:0.55–0.72) for both intra- and inter-rater comparisons. Preoperative ICCs were lower: 0.55–0.75 (lower 95% CI:0.40–0.65). Conclusion The lower 95% confidence level for ICC of version and rotational measurements using the Berger protocol of TKRs on CT are all less than 0.73 and that the normal range of differences between observers is up to 9° for the femoral component and 26° for the tibial component. This suggests that CT measurements derived from the Berger protocol may not be consistent enough for clinical practice. Key Points • CT is commonly used to measure the rotational profile of knee replacements in symptomatic patients using the Berger protocol. • The limits of agreement for both femoral and tibial component rotation are wide even for experienced observers. • CT measurements of the rotation of knee arthroplasty are not reliable enough for routine clinical use.

Self-aligned Technique for Tibial Component Placement in Total Knee Arthroplasty Lessening Rotational Malalignment in Measured Resection and Gap-Balancing Techniques

“…Currently, three-dimensional CT has become increasingly popular as it can mitigate several factors, including lower limb position and joint contracture, which may influence the accuracy and reliability of conventional two-dimensional CT imaging. 27 28) Lastly, our study included predominantly female patients (n = 86), which may be associated with different femoral geometry compared to male patients. Koh et al 29) demonstrated gender differences in both medial and lateral posterior condyle morphology, and this could contribute to variation in the PCA between men and women.…”

3-dimensional computer tomography is more accurate than traditional long-leg radiographs in the planning and evaluation of coronal alignment in total knee arthroplasty: a prospective study on 121 knees

“…In the AURORA protocol [ 25 ] the tibial antero-posterior axis was defined by the tibial tubercle and the PCL insertion. Yoshino et al [ 24 ] defined the coronal plane as a vertical to the “Akagi line.” However, other studies have demonstrated that these landmarks are hard to define and have low interobserver reliability [ 26 , 27 ].…”

“…Yoshino et al [24] defined the coronal plane as a vertical to the "Akagi line." However, other studies have demonstrated that these landmarks are hard to define and have low interobserver reliability [26,27].…”

Preoperative patellar bone marrow lesions with full thickness cartilage defects correlate with residual anterior knee pain in total knee arthroplasty without patellar resurfacing

“…FCR was determined as the angle between the trans‐epicondylar axis and posterior condylar axis. TCR was measured according to the Berger protocol [37]. To determine the position error, internal rotation of the femoral and tibial component was negative, and external rotation was positive.…”