Reliability of patellotrochlear index in patellar height assessment on MRI-correction for variation due to change in knee flexion.

OBJECTIVES To assess the reliability of patellotrochlear Index (PTI) in patellar height assessment on successive MRI scans in asymptomatic patients. MATERIALS AND METHODS Sixty-four patients with two successive MRI scans (128 studies) of the same knee for non-patellofemoral joint symptoms were identified retrospectively. PTI and knee flexion angle were assessed independently by three observers to assess interobserver reliability. The effect of knee flexion on PTI was assessed by comparing the change in values of PTI in each patient correlated with change in knee flexion. RESULTS Sixty-four MRIs of patients (M:F) aged between 18 and 35 years (mean 24.6) years were assessed. The mean PTI for initial scan group was 0.33% (95% CI: 0.29-0.37; SD: 0.15) and consecutive scan group was 0.30% (CI: 0.27-0.33; SD: 0.3). The difference was not significant (p = 0.097 using a paired t test) with high inter-observer correlation (0.9) in both sets. Spearman's rho for knee flexion angle and PTI was found to be positive and statistically significant (0.41; p = 0.001). A linear regression model was derived using a scatter chart of change in PTI with change in knee flexion for each patient. The gradient of the linear regression line was used to estimate a cPTI (corrected PTI) value (corrected to 0 degrees of knee flexion), defined as cPTI = PTI - 1.3a (a = knee flexion angle). CONCLUSIONS This study demonstrates high inter-observer correlation of PTI on MRI and high test-retest reliability indicating unconscious quadriceps contraction does not change the index sufficiently. Knee flexion significantly alters PTI, increased patellotrochlear engagement with flexion increases the index. We propose use of the formula cPTI = PTI -1.3a to correct the index to 0 degree knee flexion in clinical practice

Tip malposition of peripherally inserted central catheters: a prospective randomized controlled trial to compare bedside insertion to fluoroscopically guided placement

Objective: Peripherally inserted central catheter (PICC) use continues to increase, leading to the development of a blind bedside technique (BST) for placement. The aim of our study was to compare the BST with the fluoroscopically guided technique (FGT), with specific regard to catheter tip position (CTP). Materials and methods: One hundred eighty patients were randomized to either the BST or the FGT. All procedures were done by the same interventional team and included postprocedural chest X-ray to assess CTP. Depending on the international guidelines for optimal CTP, patients were classified in three types: optimal, suboptimal not needing repositioning, and nonoptimal requiring additional repositioning procedures. Fisher's test was used for comparisons. Results: One hundred seventy-one PICCs were successful inserted. In the BST groups, 23.3% of placements were suboptimal and 30% nonoptimal, requiring repositioning. In the FGT group, 5.6% were suboptimal and 1.1% nonoptimal. Thus, suboptimal and nonoptimal CTP were significantly lower in the FGT group (p &lt; 0.001). Conclusion: Tip malposition rates are high when using blind BST, exposing the patient to an increased risk of deep venous thrombosis and catheter malfunction. Using the FGT or emerging technologies that could help tip positioning are recommended, especially for long-term indications. Key points: • Bedside and fluoroscopy guided techniques are commonly used for PICC placement. • Catheter malposition is the major technical issue with the bedside technique. • Catheter malposition occurred in 53% of patients with the bedside technique.</p