Intra- and inter-observer variation during femoral jig rotational alignment in knee arthroplasty

Introduction/aims

Rotational alignment of the femoral prosthesis is important in total knee arthroplasty to improve performance and reduce complications. This study investigates the differences between two popular referencing methods and evaluates the variability of surgeons’ techniques (inter-observer) and their reproducibility (intra-observer) of femoral alignment.

Methods

Eight surgeons each established the femoral rotational alignment on four duplicate sets of six cadaveric femoral bone casts, referencing from the epicondylar axis and from the posterior femoral condyles. These derived axes were compared against a reference Whiteside’s line (anteroposterior axis).

Results/summary

There was no significant difference between referencing techniques and a tendency to align the femoral component in slight external rotation. Femoral rotational alignment was reproducible by each surgeon. Extensive and significant variation in alignment exists between surgeons, independent of other factors (p < 0.001).