A Comparison of Component Positioning Between Fluoroscopy-Assisted and Robotic-Assisted Total Hip Arthroplasty.

BACKGROUND: This single-surgeon retrospective study examined a consecutive series of direct anterior approach total hip arthroplasties (THAs). Differences for the accuracy of acetabular component placement, leg length discrepancy, femoral offset, and absolute global offset difference were measured for patients who underwent hip replacement surgery with either fluoroscopic or robotic guidance. METHODS: One hundred THAs were included in both the fluoroscopically guided and robotically guided groups in the study. The program TraumaCad was used to analyze the preoperative and 6-week postoperative standing anteroposterior pelvic radiographs used in this study to evaluate the accuracy of component positioning. RESULTS: Robotic-guided surgery demonstrated a small improvement in acetabular inclination error, 3.8° average robotic error vs 4.63° average fluoroscopic error (P < .01). There was no statistically significant difference in accuracy for acetabular anteversion, leg length discrepancy, femoral offset, or global offset difference between the 2 groups. There was also no significant difference in the placement of acetabular components into the Lewinnek safe zone or Callanan safe zone. Both fluoroscopically guided and robotically guided THA patients had similar patterns of error, with excessive anteversion and inclination being more common than inadequate anteversion or inclination. CONCLUSION: The findings from our study question the use of haptic robotic guidance during direct anterior approach THA when compared to fluoroscopic guidance.

Are only infants held more often on the left? If so, why? Testing the attention-emotion hypothesis with an infant, a vase, and two chimeric tests, one "emotional," one not.

Most adults, especially women, hold infants and dolls but not books or packages on the left side. One reason may be that attention is more often leftward in response to infants, unlike emotionally neutral objects like books and packages. Women's stronger bias may reflect greater responsiveness to infants. Previously, we tested the attention hypothesis by comparing women's side-of-hold of a doll, book, and package with direction-of-attention on the Chimeric Faces Test (CFT) [Harris, L. J., Cárdenas, R. A., Spradlin, Jr., M. P., & Almerigi, J. B. (2010). Why are infants held on the left? A test of the attention hypothesis with a doll, a book, and a bag. Laterality: Asymmetries of Body, Brain and Cognition, 15(5), 548-571. doi:10.1080/13576500903064018]. Only the doll was held more often to the left, and only for the doll were side-of-hold and CFT scores related, with left-holders showing a stronger left-attention bias than right-holders. In the current study, we tested men and women with a doll and the CFT along with a vase as a neutral object and a "non-emotional" chimeric test. Again, only the doll was held more often to the left, but now, although both chimeric tests showed left-attention biases, scores were unrelated to side-of-hold. Nor were there sex differences. The results support left-hold selectivity but not the attention hypothesis, with or without the element of emotion. They also raise questions about the contribution of sex-of-holder. We conclude with suggestions for addressing these issues.

Fluoroscopy assessment during anterior minimally invasive hip replacement is more accurate than with the posterior approach.

PURPOSE: Acetabular component position is important for stability and wear. Fluoroscopy can improve the accuracy of acetabular component placement in the posterior approach and the direct anterior approach (DAA). The purpose of this study was to determine if the direct anterior approach in the supine position facilitates the accurate use of fluoroscopy and improves acetabular component position. METHODS: This retrospective, comparative study of 60 THAs with fluoroscopic guidance (30 in posterior approach group and 30 in DAA group) was performed by one surgeon from 2012 to 2014 at a single institution. Demographic and perioperative data were compared using the Kolmogorov-Smirnov test to determine if they were statistically different. The difference between the measured intra-operative and postoperative values for both inclination and anteversion were analysed respectively. RESULTS: In the posterior approach group we found an average inclination on intra-operative fluoroscopy (IFluoro) of 36.8° ± 3.72°, an average anteversion on intra-operative fluoroscopy (AFluoro) of 25.6° ± 3.64°, an average inclination on postoperative standing AP pelvis X-ray (IAP X-ray) of 39.29° ± 4.58° and an average anteversion on postoperative standing AP pelvis X-ray (AAP X-ray) of 21.31° ± 4.04°. In the DAA group we found an average DAA IFluoro of 42.32° ± 1.91°, an average DAA AFluoro of 22.3° ± 1.41°, an average DAA IAP X-ray of 42.98° ± 1.81° and an average DAA AAP X-ray of 22.88° ± 1.38°. A difference was seen in variability using Kolmogorov-Smirnov test for inclination and anteversion with significant higher variation of measurements in the posterior approach group (p = 0.022 and p < 0.001 respectively). No statistically significant difference was seen in the DAA group using the fluoroscopy for inclination and anteversion. CONCLUSION: Using fluoroscopy in the direct anterior approach, we achieved better intra-operative assessment of cup orientation resulting in decreased variability of acetabular cup anteversion than when used in the posterior approach. At least some of the improvement was due to the fact that the fluoroscopic image in the supine position was more accurate as measured against the postoperative standing AP pelvis. This study may influence the choice of approach in total hip replacement.

The Coherent X-ray Imaging instrument at the Linac Coherent Light Source.

The Coherent X-ray Imaging (CXI) instrument specializes in hard X-ray, in-vacuum, high power density experiments in all areas of science. Two main sample chambers, one containing a 100 nm focus and one a 1 µm focus, are available, each with multiple diagnostics, sample injection, pump-probe and detector capabilities. The flexibility of CXI has enabled it to host a diverse range of experiments, from biological to extreme matter.