Effect of rotational alignment on outcome of total knee arthroplasty: A systematic review of the literature and correlation analysis

Background and purpose

Poor outcomes have been linked to errors in rotational alignment of total knee arthroplasty components. The aims of this study were to determine the correlation between rotational alignment and outcome, to review the success of revision for malrotated total knee arthroplasty, and to determine whether evidence-based guidelines for malrotated total knee arthroplasty can be proposed.

Patients and methods

We conducted a systematic review including all studies reporting on both rotational alignment and functional outcome. Comparable studies were used in a correlation analysis and results of revision were analyzed separately.

Results

846 studies were identified, 25 of which met the inclusion criteria. From this selection, 11 studies could be included in the correlation analysis. A medium positive correlation (ρ = 0.44, 95% CI: 0.27–0.59) and a large positive correlation (ρ = 0.68, 95% CI: 0.64–0.73) were found between external rotation of the tibial component and the femoral component, respectively, and the Knee Society score. Revision for malrotation gave positive results in all 6 studies in this field.

Interpretation

Medium and large positive correlations were found between tibial and femoral component rotational alignment on the one hand and better functional outcome on the other. Revision of malrotated total knee arthroplasty may be successful. However, a clear cutoff point for revision for malrotated total knee arthroplasty components could not be identified.About 1 in 5 TKA patients are dissatisfied with the outcome (Bourne et al. 2010). A systematic review by the European Arthroplasty Register reported the results of 6 national joint registry datasets. A combined revision rate of 1.3 revisions per 100 observed component years after primary TKA was reported, and revision rates of about 6% after 5 years and 12% after 10 years are to be expected (Labek et al. 2011). Many possible causes of painful or malfunctioning TKAs have been defined, but the true cause often remains unknown (Thornhill 2002, Dennis 2004, Toms et al. 2009). Rotational errors of TKA components are frequently overlooked as the origin of problems, which can lead to unnecessary procedures (Bedard et al. 2011). Poor outcomes and major complications—e.g. patellofemoral pain, instability, and stiffness after TKA—have been linked to errors in rotational alignment of the components (Mochizuki and Schurman 1979, Rhoads et al. 1990, Berger et al. 1998, Miller et al. 2001, Sikorski 2008). Thus, the aims of the present study were (1) to examine the correlation between rotational alignment of the TKA component and outcome, (2) to review the results of revision operations for rotational malaligned TKA, and (3) to investigate whether practical recommendations can be made to guide treatment of a rotational malaligned TKA.