FUNCTIONAL AND RADIOLOGICAL OUTCOME OF NAVIGATED KNEE ARTHROPLASTY. DOES ACCURACY MAKE A DIFFERENCE?

Abstract

Computer navigation has the potential to revolutionise orthopaedic surgery. It is widely accepted that component malalignment and malrotation leads to early failure in knee arthroplasty. We aimed to assess the use and reliability of computer navigation in both total (TKR) and unicompartmental (UKR) knee replacement surgery.

We analysed 40 consecutive UKRs and 40 consecutive TKRs. All procedures were carried out with the Brain-LAB navigation system and all were carried out by one consultant orthopaedic surgeon. Preoperative aim was neutral tibial cuts with 3 degrees posterior slope. Coronal and sagittal alignment of tibial components were measured on postoperative radiographs. Patients were also scored clinically with regards to function and pain.

In the TKR group, mean tibial coronal alignment was 0° (range 1 to −2.) Mean sagittal alignment was 2° posterior slope (range 0 to 4.) In the UKR group, mean tibial coronal alignment was 0.55° (range 0 to −3.) Mean sagittal alignment was 2.1° posterior slope (range 0 to 4°.) Clinical outcome scores were very satisfactory for the majority of patients, with far superior functional scores in the UKR group.

Our results demonstrate very accurate placement of the prosthesis in both the TKR and UKR group with computer navigation. There is a very narrow range with no outliers, (all within +/−3 degrees of desired alignment.) Functional outcome scores are good. We advocate the use of computer navigation in unicompartmental as well as total knee replacment surgery, in order to minimise early failures.