Constrained acetabular liners in hip revision surgery. A low-cost solution for senile patients.

The objective of this study was to analyze the results of a cemented polyethylene model that captures the hip prosthetic head. In a retrospective study we reviewed 36 cemented constrained acetabular liners implanted in patients older than 75 years (mean 83, SD : 4.4), of which 30 patients were aged 80-90 years and 26 were women. The average period of follow-up of our patients was 25.4 months (12-39 months, SD : 7.3). In 26 patients this model was implanted due to recurrent dislocation or instability, in 8 other cases this model was implanted during revision surgery for periprosthetic fractures, aseptic loosening of the -acetabular component, wear of the polyethylene or replacement of the implant because of infection. There was a single case of recurrent dislocation (2.8%). Cemented acetabular constrained liners are a good option in revision surgery in senile patients in which the femoral stem is firmly fixed to the bone.

Computer-assisted navigation in total knee arthroplasty without femoral hardware removal.

PURPOSE OF THE STUDY: The use of navigation applied to total knee arthroplasty in knees with femoral hardware retained has not been studied. MATERIAL AND METHODS: We use navigation in six patients to implant a total knee arthroplasty while retaining the femoral hardware. The retained materials were screws in two cases, diaphyseal plates in another two, intramedullary nails in one and supracondylar tube/plate in another one. Preoperative knee scores were within the 46-66 range, whereas the functional scores were within 40-68. The coronal deformity varied between 30° varus and 5° valgus. RESULTS: The final femoral mechanical axis was between 2° valgus and 3° varus; the axis of the limb was between 4° valgus and 3° varus. Knee scores improved in all cases, with scores between 75 and 90 points (p = 0.028); functional scores were between 64 and 90 points (p = 0.043).The final range of mobility was within the 70°-110° range, with a slight improvement over the preoperative status (p = 0.042). No complications have arisen throughout the follow-up (mean 16 months). CONCLUSIONS: The use of navigation constitutes a good option in the treatment with total arthroplasties for patients with femoral hardware retained.

Metal-on-metal surface hip arthroplasties. Is annual monitoring of blood metal levels necessary? / Artroplastias de superficie metal-metal en cadera. ¿Es necesario realizar seguimiento anual mediante determinación de metales en sangre?

INTRODUCTION: Blood cobalt (Co) and chromium (Cr) ion levels have been used as surveillance tools for adverse reaction to metal debris in metal-on-metal (MoM) hip arthroplasty. The aim of our study was to present serial 7-13 year blood Co and Cr levels in a cohort of MoM total hip arthroplasties in asymptomatic patients. MATERIAL AND METHODS: A total of 52 MoM surface total hip arthroplasties were included in this study with data collected prospectively. Annual follow-up with blood Co and Cr measurements was performed. Revision surgery was necessary for 16 patients and therefore they dropped out of the study. The metal ion levels were analyzed separately in 31 asymptomatic patients. RESULTS: High Cr or Co levels were not found continuously in any of the asymptomatic patients. The median Cr in blood was maintained between 1.3 and 5.4µg/L and that of Co between 0.5 and 1.2µg/L. After 7 years, there was no significant change in Co and Cr values. CONCLUSION: In the medium term and in asymptomatic patients, the metallic blood levels remained unchanged; therefore, it does not seem appropriate to repeat these tests on a permanent basis in annual controls.