Measurement techniques to determine tibial rotation after total knee arthroplasty are less accurate than we think.

BACKGROUND: The present study assessed the inter- and intra-observer reliability of tibial and femoral rotation measures after total knee arthroplasty (TKA), and evaluated the correlation between these measurement techniques and their clinical relevance.

METHODS: Femoral rotation and tibial rotation were determined on 42 2D CT-scans made three-months after TKA. Reliability of the radiological measurements (including Berger's method, the anatomical tibial axis and the tibial tuberosity trochlear-groove) was assessed with 15 randomly selected patients measured twice by three observers. Functional outcomes were scored one-year postoperatively with the KSS, VAS pain, VAS satisfaction, KOOS, and Kujala.

RESULTS: The inter- and intra-observer reliability of the rotational measurements ranged from good to excellent (ICC 0.67-0.98). Tibial rotation measured with the Berger technique was most reliable (ICC inter = 0.91; ICC intra = 0.96). No strong correlations were found between the different rotational measures or the clinical outcomes and rotational outliers.

CONCLUSIONS: Tibial rotation is most reliable measured with the technique described by Berger. There were no strong correlations found between the different tibial rotation measures or between the clinical outcomes and the rotational outliers. Further research is needed to gain more insight into optimal positioning and measuring rotation in TKA for clinical practice.