Summary

There was a significant deviation between the alignments of the bone resection surfaces and the final alignments of components in case of larger preoperative and postoperative flexion contractures in the coronal and sagittal planes after cemented TKA

Abstract

Purpose

To examine, with a navigation, whether the final component alignments coincide with alignment of the bone resection surfaces in cemented total knee arthroplasty(TKA), and to evaluate the factors affecting the alignment deviation.

Methods

A total of 222 patients(276 knees) who received navigation-assisted TKA between September 2012 to January 2014 due to osteoarthritis were retrospectively reviewed. The deviation between the alignment of bone resection surface and the final alignment of femoral and tibial components was measured. The factors that can affect alignment deviation of greater than 2°(outliers) were evaluated. These included age, gender, body mass index, bone mineral density(T-score), preoperative and postoperative mechanical femorotibial angle, preoperative and postoperative flexion contractures, and difference between medial and lateral gaps in knee extension or flexion.

Results

Outliers consisted of 24 cases(8.6%) on the femoral coronal plane, four cases(1.4%) on the tibial coronal plane, and 48 cases(17.4%) on the tibial sagittal plane. In the coronal plane(femur and tibia), the outliers were associated with preoperative(p<0.001; odds ratio[OR], 0.774; 95% confidence interval[CI], 0.672 to 0.891) and postoperative(p<0.001; OR, 0.240; 95% CI, 0.123 to 0.468) flexion contractures; a difference of 3 mm or more between the medial and lateral gaps in knee extension(p<0.041; OR, 5.805; 95% CI, 1.075 to 31.343); and a T-score of less than -2.5(p<0.024; OR, 5.899; 95% CI, 1.258 to 27.664). In the sagittal plane of the tibia, the outliers were associated with preoperative(p<0.001; OR, 0.886; 95% CI, 0.829 to 0.946) and postoperative(p<0.031; OR, 0.803; 95% CI, 0.659 to 0.980) flexion contractures.
Conclusion:There was a significant deviation between the alignments of the bone resection surfaces and the final alignments of components. With larger preoperative and postoperative flexion contractures in the coronal and sagittal planes, there were more outlier risks. The outliers in the coronal plane were associated with a difference of 3 mm or more between the medial and lateral gaps in knee extension and poor bone quality.