Effects of the Balanced Gap Technique on Femoral Component Rotation in TKA

Femoral component rotation from a total knee prosthesis can be determined by either a measured resection technique or a balanced gap technique. With the balanced gap implantation technique, femoral component rotation can vary freely within the restrictions produced by soft tissue structures. Because internal rotation might cause patella problems, the effect of ligament releases on femoral component rotation in a prospective clinical study was studied. Femoral component rotation was measured intraoperatively with a tensor applied in flexion at 150 N in 87 knees. Great interpatient variability was found; femoral component rotation, reference from the posterior condyles, ranged from −4° to 13°. There was no difference in femoral component rotation of knees with or without ligament releases in extension. However, knees with major medial release had less external femoral component rotation than knees with minor lateral releases. Preoperative alignment had no influence on femoral component rotation. The use of the balanced gap implantation technique theoretically will result in a balanced flexion gap, but the amount of femoral component rotation will be variable owing to patient variability and variation in ligament releases

Age, gender, functional KSS, reason for revision and type of bone defect predict functional outcome 5years after revision total knee arthroplasty: a multivariable prediction model

Contains fulltext : 206034.pdf (publisher's version ) (Open Access

No effect of additional screw fixation of a cementless, all-polyethylene press-fit socket on migration, wear, and clinical outcome: A 6.5-year randomized radiostereometric analysis follow-up report

Background and purpose — Additional screw fixation of the all-polyethylene press-fit RM cup (Mathys) has no additional value for migration, in the first 2 years after surgery. However, the medium-term and long-term effects of screw fixation remain unclear. We therefore evaluated the influence of screw fixation on migration, wear, and clinical outcome at 6.5 years using radiostereometric analysis (RSA). Patients and methods — This study involved prolonged follow-up from a previous randomized controlled trial (RCT). We analyzed RSA radiographs taken at baseline and at 1-, 2-, and 6.5-year follow-up. Cup migration and wear were assessed using model-based RSA software. Wear was calculated as translation of the femoral head model in relation to the cup model. Total translation, rotation, and wear were calculated mathematically from results of the orthogonal components. Results — 27 patients (15 with screw fixation and 12 without) were available for follow-up at 6.5 (5.6–7.2) years. Total translation (0.50 mm vs. 0.56 mm) and rotation (1.01 degrees vs. 1.33 degrees) of the cup was low, and was not significantly different between the 2 groups. Wear increased over time, and was similar between the 2 groups (0.58 mm vs. 0.53 mm). Wear rate (0.08 mm/year vs. 0.09 mm/year) and clinical outcomes were also similar. Interpretation — Our results indicate that additional screw fixation of all-polyethylene press-fit RM cups has no additional value regarding medium-term migration and clinical outcome. The wear rate was low in both groups

Challenges in Modelling Infectious Disease Dynamics:Preface

This special issue of Epidemics arises from a research programme on ‘Infectious Disease Dynamics’ held at the Isaac Newton Institute for Mathematical Sciences in Cambridge, UK in August–September 2013, with a follow-up in May–June 2014.1 This programme marked the 20-year anniversary of a 1993 programme on ‘Epidemic Models’ at the Newton Institute, which played a major role in consolidating progress and charting a path forward for the field. Many readers of Epidemics will be familiar with the three ‘blue books’ that gathered the insights from this seminal gathering (Mollison, 1995; Grenfell and Dobson, 1995; Isham and Medley, 1996). The 2013 programme began with a week-long symposium, at which an international roster of speakers described progress from the last 20 years and presented their vision of progress to come. This was followed by three weeks of close interactions and intensive discussions among a smaller group, focused on identifying the major challenges currently faced by the field. This volume presents the outcome of these and subsequent discussions