Introduction: The aim of this study is to assess the safety and efficacy of initial results seen with minimally invasive techniques in navigator-assisted TKR.

Materials and methods: A consecutive series of 50 TKRs with the same model are included in the study. These were carried out by the same surgical team, using a standardized navigator-assisted technique and a minimally invasive “midvastus” approach. Follow-up was from 3 to 24 months. The efficacy of the procedure is studied by assessing preoperative and early postoperative pain and mobility, final alignment obtained and safety, based on any subsequent complications.

Results: Decrease of pain was seen in 49 patients, with a range of movement from 0° to 110° in 47 patients. There were no significant complications such as infection or thromboembolism. There were no alignment (varus/valgus) alterations on the frontal plane greater than 3°, nor relevant alterations on the sagittal plane. Complications with surgical wound healing were seen in 3 cases; these did not require special procedures; 9 cases had slight and transient pain in the proximal area of the surgical wound.

Conclusions: Initial results allow us to consider that the technique studied is effective and safe. However, we have detected problems with pain of doubtful etiology in the proximal part of the surgical wound while healing. We believe that the use of a navigator ensures greater safety in the use of minimally invasive techniques and provides a spatial view of the knee joint.

(*) This study is part of a study financed by the Fund for Health Research of the Biomedical and Health Sciences Promotion Program (Spanish Ministry of Health and Consumption) (File PI05-1065)(Fondo de Investigaciòn Sanitaria del Programa de Promociòn de la Investigaciòn Biomédica y en Ciencias de la Salud (Ministerio de Sanidad y Consumo) (Expediente PI05– 1065)

Background: Measurement of quality of life (QOL) and functional status provides important additional information for priority setting in health policy formulation and resource allocation. Our aim was to define the differences in the health-related quality of life between hip artroplasties with cementation and without cementation. The last objective was to reunite evidences on the advantages and disadvantages of both systems of hip arthroplasty fixation. Methods: We analyzed a random sample of patients in surgical waiting list of total hip arthroplasty, between 65 and 75 years, divided in two groups of 40 patients who received a cemented or uncemented THA, respectively. We compared the pre-operative characteristics and at a year after operation changes in the Nottingham Health Profile (NHP) and SF-12 self-administered questionnaires. We also performed the specific Harris hip score. To make the different scoring systems comparable, all scores were transformed to a 0-to 100-point scale, with 100 points indicating best health. Differences among these groups were compared using the Mann-Whitney U test. Results: All patients increased their QOL scores. Both groups had similar QOL scores before surgery. At 1 year, patients with the uncemented prosthesis had slightly higher scores for energy, pain, and emotional reaction. Changes in QOL scores were, however, very similar. Conclusions: The use of an uncemented prosthesis does not impair early outcome.

Introduction and purpose: The failure of a TKP is often due to deficiencies related to alignment, stability or fixation. The purpose of this paper is to determine how loads are distributed when each of two tibial stem models are implanted and to assess those loads densitometrically.

Materials and methods: We analyzed 20 patients with a cemented TKR and divided them into two groups according to whether their tibial stem was cylindrical or cruciform. We studied the evolution of periprosthetic bone density under the internal and external bearings and under the stem. We performed a densitometry after 2 years postop and controls after 3 and 7 years.

Results: In the cylindrical stem group the evolution of mean bone density under the internal bearing after 2 and 3 years was 0.92±0.20 to 0.90±0.19 g/cm2 respectively; mean bone density under the external bearing was 0.97±0.36 to 0.97±0.38 and under the stem it was 1.05±0.25 to 1.08±0.26. In the cruciform group, density under the internal bearing was 0.75±0.08 to 0.71±0.05, under the external one it was 0.89±0.01 to 0.85±0.07 and under the stem it was 1.06±0.06 to 1.04±0.29. In the long term (three patients were lost to follow-up), comparing the cylindrical prostheses to one another, we can say that the evolution under the internal bearing after 2, 3 and 7 years was 0.88, 0.84 and 0.80 g/cm2 respectively; under the external bearing it was 0.79, 0.78 and 0.77 and under the stem it was 0.99, 0.96 and 0.99.

Conclusions: After TKR a progressive loss of bone density is observed. Comparatively, the reduction is greater in the cruciform stem. The internal compartment is the most affected one.