Letters to the editor

Abstract

There is agreement at the present time about the need to obtain the correct limb alignment after a knee arthroplasty [1Lotke P Ecker M Influence of positioning of prosthesis in total knee replacement.J Bone Joint Surg Am. 1977; 59: 77PubMed Google Scholar, 2Matsuda S Miura H Nagamine R et al.Changes in knee alignment after total knee arthroplasty.J Arthroplasty. 1999; 14: 566Abstract Full Text PDF PubMed Scopus (69) Google Scholar], although it also is known that, in many situations, this is a difficult aim to reach with the current instrumentation [3Nuño-Siebrecht N Tanzer M Bobyn J.D Potential errors in axial alignment using intramedullary instrumentation for total knee arthroplasty.J Arthroplasty. 2000; 15: 228Abstract Full Text PDF PubMed Scopus (52) Google Scholar]. The article “Implant Position in Knee Surgery: A Comparison of Minimally Invasive, Open Unicompartmental, and Total Knee Arthroplasty,” published in Supplement 1 of the October 2003 issue of the Journal of Arthroplasty [4Fisher D.A Watts M Davis K.E Implant position in knee surgery a comparison of minimally invasive, open unicompartmental, and total knee arthroplasty.J Arthroplasty. 2003; 18: 2Abstract Full Text Full Text PDF PubMed Scopus (98) Google Scholar], appears a comparative study of the position of the knee implant and the limb alignment after total knee arthroplasty, standard unicompartmental knee arthroplasty (UKA) and minimally invasive UKA. The limb alignment and the implant position are measured using the location point on preoperative and postoperative, standard 18-inch radiographs. From our point of view, the radiographic references for the measurement of the femoral and tibial axes are not sufficient, because it is necessary to include the ankle and the hip in the same radiograph. The measurement of the femoral and tibial axes without the inclusion of the ankle and the hip in the same radiograph is not a valid method to ascertain the true limb alignment. A radiograph could be a valid method of ascertaining the position of the implant of the distal femoral and proximal tibial axes, but we do not think it is a valid for the true femoral, tibial, and limb axes. We believe that a study that it is based on the analysis of the implant position in relation to the limb axis should have considered this circunstance. The measurement method showed in this study could be used to compare the local position of the implant between the 3 analyzed techniques, but not the postoperative limb alignment. In replyThe Journal of ArthroplastyVol. 19Issue 5Preview Full-Text PDF