Intraoperative frozen section histopathology for the diagnosis of periprosthetic joint infection in hip revision surgery: the influence of recent dislocation and/or periprosthetic fracture.

AIMS: To evaluate the accuracy of intraoperative frozen section histopathology for diagnosing periprosthetic joint infection (PJI) during hip revision surgery, both for patients with and without recent trauma to the hip. PATIENTS AND METHODS: The study included all revision total hip replacement procedures where intraoperative frozen section histopathology had been used for the evaluation of infection in a single institution between 2008 and 2015. Musculoskeletal Infection Society criteria were used to define infection. 210 hips were included for evaluation. Prior to revision surgery, 36 hips had a dislocation or a periprosthetic fracture (group A), and 174 did not (group B). RESULTS: The prevalence of infection was 14.3% (5.6% in group A and 16.1% in group B). Using Feldman criteria, the sensitivity of histopathology was 50.0%, specificity 47.1%, positive predictive value 5.3% and negative predictive value 94.1% in group A. The sensitivity of frozen section histopathology was 75.0%, specificity 96.5%, positive predictive value 85% and negative predictive value 95.3% in group B. CONCLUSIONS: Intraoperative frozen section histopathology is reliable for the diagnosis of PJI if no dislocation or periprosthetic fracture has occurred prior to hip revision surgery.

The Transverse Gravitational Deviation Index, a Novel Gravity Line-Related Spinal Parameter, Relates to Balance Control and Health-Related Quality of Life in Adults With Spinal Deformity.

STUDY DESIGN: Prospective cross-sectional case-control study design. OBJECTIVE: This study aims to analyze the relation between balance control as well as health-related quality of life (HRQOL) in patients with adult spinal deformity (ASD), with a novel gravity line (GL)-related 3D spinal alignment parameter, the transverse gravitational deviation index (TGDI), defined to quantify the transverse plane position of any vertebra with respect to the GL. SUMMARY OF BACKGROUND DATA: Demographic data and balance control have both been identified as important determinants of HRQOL in ASD patients during a preoperative setting. Therefore, a better understanding of the relation between spinal alignment and balance is required. METHODS: After informed consent, 15 asymptomatic healthy volunteers (mean age 60.1 ±â€Š11.6 years old) and 55 ASD patients (mean age 63.5 ±â€Š10.1 years old) were included. Relation between performance on BESTest as well as core outcome measures index (COMI) with spinopelvic alignment was explored using General Linear Modeling (GLM). A P-value ≤0.05 was considered statistically significant. RESULTS: The L3 TGDI was identified to relate to balance control in the total ASD population after correction for confounding demographic factors (P = 0.001; adjusted R = 0.500) and explained 19% of the observed variance in balance performance. In addition, COMI is related to L3 TGDI in a subgroup of ASD patients with combined coronal and sagittal malalignment of L3 (P = 0.027; slope B = 0.047), despite significant influence of age (P = 0.020). CONCLUSION: In ASD patients with a combined coronal and sagittal malalignment of the L3 vertebra, both the level of balance impairment as well as HRQOL are related to the distance component of the L3 TGDI, that is, the offset between the center of the L3 vertebral body and the GL in the transverse plane. LEVEL OF EVIDENCE: 2.

Performance on Balance Evaluation Systems Test (BESTest) Impacts Health-Related Quality of Life in Adult Spinal Deformity Patients.

STUDY DESIGN: Prospective single-center study. OBJECTIVE: Study investigates how dynamic balance performance complements 2D static radiographic measurements and demographics in terms of understanding health-related quality of life in adult spinal deformity (ASD) patients. SUMMARY OF BACKGROUND DATA: Recent insights suggest that demographic variables have a stronger impact on health-related quality of life than 2D radiographic spinopelvic parameters in ASD patients. METHODS: Nine healthy volunteers and 36 ASD patients following inclusion criteria were recruited. Demographics, Scoliosis Research Society Score-22r (SRS-22r), Oswestry Disability Index (ODI), Core Outcome Measures Index (COMI), 2D radiographic spinopelvic measurements, and performance on Balance Evaluation Systems Test (BESTest), and Trunk Control Measurement Scale (TCMS) were determined for each subject. Nonparametric tests, Spearman correlations, univariate, and stepwise-like linear multivariate regression analysis were performed. RESULTS: BESTest and TCMS had significant lower values in the ASD group versus the control group (P = 0.000). In the ASD group, Cumulative Illness Rating Scale (CIRS) correlated fair to ODI, COMI (0.441 ≥ r ≥ 0.383, P < 0.021) and to SRS-22-r (r = -0.335, P = 0.046), Mini Mental State Examination correlated fair to COMI (r = -0.352, P = 0.035), "Pelvic Incidence minus Lumbar Lordosis" correlated fair to ODI (r = 0.361, P = 0.031), BESTest correlated moderate to ODI and COMI (r ≤ -0.505; P ≤ 0.002), TCMS correlated fair to ODI (r = -0.356; P = 0.033). CIRS and BESTest were significant predictive variables for COMI based on univariate analysis in ASD patients. Multivariate regression analysis including demographics, 2D static radiographic parameters, and dynamic balance scales identified BESTest as single independent variable (P = 0.000) to predict COMI (adjusted R = 0.285) in ASD patients. CONCLUSION: BESTest has a higher potential than demographic and 2D radiographic spinopelvic parameters to predict quality of life in ASD patients. Further research is necessary to identify the impact of ASD on quality of life. LEVEL OF EVIDENCE: 3.

Temporal dynamics of different cases of bi-stable figure-ground perception.

Segmentation of a visual scene in "figure" and "ground" is essential for perception of the three-dimensional layout of a scene. In cases of bi-stable perception, two distinct figure-ground interpretations alternate over time. We were interested in the temporal dynamics of these alternations, in particular when the same image is presented repeatedly, with short blank periods in-between. Surprisingly, we found that the intermittent presentation of Rubin's classical "face-or-vase" figure, which is frequently taken as a standard case of bi-stable figure-ground perception, often evoked perceptual switches during the short presentations and stabilization was not prominent. Interestingly, bi-stable perception of Kanizsa's anomalous transparency figure did strongly stabilize across blanks. We also found stabilization for the Necker cube, which we used for comparison. The degree of stabilization (and the lack of it) varied across stimuli and across individuals. Our results indicate, against common expectation, that the stabilization phenomenon cannot be generally evoked by intermittent presentation. We argue that top-down feedback factors such as familiarity, semantics, expectation, and perceptual bias contribute to the complex processes underlying the temporal dynamics of bi-stable figure-ground perception.