Infrapatellar fat pad abnormalities are associated with a higher inflammatory synovial fluid cytokine profile in young adults following ACL tear

OBJECTIVE

To evaluate the degree of knee fat pad abnormalities after acute anterior cruciate ligament (ACL) tear via magnetic resonance fat pad scoring and to assess cross-sectionally its association with synovial fluid biomarkers and with early cartilage damage as quantified via T1ρ and T2 relaxation time measurements.

DESIGN

26 patients with acute ACL tears underwent 3T MR scanning of the injured knee prior to ACL reconstruction. The presence and degree of abnormalities of the infrapatellar (IPFP) and the suprapatellar (SPFP) fat pads were scored on MR images along with grading of effusion-synovitis and synovial proliferations. Knee cartilage composition was assessed by 3T MR T1ρ and T2 mapping in six knee compartments. We quantified concentrations of 20 biomarkers in synovial fluid aspirated at the time of ACL reconstruction. Spearman rank partial correlations with adjustments for age and gender were employed to evaluate correlations of MR, particularly cartilage composition and fat pad abnormalities, and biomarker data.

RESULTS

The degree of IPFP abnormality correlated positively with the synovial levels of the inflammatory cytokine markers IFN-γ (ρpartial = 0.64, 95% CI (0.26-0.85)), IL-10 (ρpartial = 0.47, 95% CI (0.04-0.75)), IL-6 (ρpartial = 0.56, 95% CI (0.16-0.81)), IL-8 (ρpartial = 0.49, 95% CI (0.06-0.76)), TNF-α (ρpartial = 0.55, 95% CI (0.14-0.80)) and of the chondrodestructive markers MMP-1 and -3 (MMP-1: ρpartial = 0.57, 95% CI (0.17-0.81); MMP-3: ρpartial = 0.60, 95% CI (0.21-0.83)). IPFP abnormalities were significantly associated with higher T1ρ and T2 values in the trochlear cartilage (T1ρ: ρpartial = 0.55, 95% CI (0.15-0.80); T2: ρpartial = 0.58, 95% CI (0.18-0.81)) and with higher T2 values in the medial femoral, medial tibial as well as in patellar cartilage (0.45 ≤ ρpartial ≤ 0.59). Correlations between SPFP abnormalities and synovial markers were not significant except for IL-6 (ρpartial = 0.57, 95% CI (0.17-0.81)).

CONCLUSIONS

This exploratory study suggests that acute ACL rupture can be associated with damage to knee tissues such as the inferior fat pad of the knee. Such fat pad injury could be partially responsible for the apparent post-injury pro-inflammatory response noted in ACL-injured individuals. However, future longitudinal studies are needed to link ACL-rupture associated fat pad injury with important patient outcomes such as the development of posttraumatic osteoarthritis.

Topographic quantitative EEG measures of alpha and theta power changes during caffeine withdrawal: preliminary findings from normal subjects

Neurophysiological consequences of withdrawal from caffeine are poorly understood. In particular, quantitative studies of EEG changes that may occur during the period of caffeine abstinence in caffeine dependent individuals have not been reported. In this pilot study, 13 physically- and psychiatrically-normal caffeine users were asked to abstain from caffeine for a period of 4 days. Quantitative EEGs were obtained prior to stopping caffeine and on Days 1, 2, and 4 of the caffeine abstinence period. Results indicated that significant increases in alpha and theta absolute power accompany the caffeine withdrawal process with return to the pre-abstinent EEG levels when caffeine usage is resumed. The implications of these findings are discussed with special reference to the possible need to control for the variable of caffeine usage in quantitative EEG studies of other phenomena.

A standardized form for DSM-IV review of symptoms and mental status examination for students and residents

A common error by medical students and residents is the inadvertent omission of some part of the mental status examination or failure to screen for a psychiatric diagnosis that is not evident on the patient's presentation. The authors introduce a structured questionnaire and standardized form to guide psychiatric and generalist medical trainees through the mental status examination. Based on criteria from the Diagnostic and Statistical Manual of Mental Disorders--Fourth Edition (DSM-IV), the questionnaire and form are intended to facilitate a psychiatric review of patients without missing key points.

A short evaluation of a new haematological cell counter--the Cell-Dyn 3000--following a modified tentative NCCLS-procedure

The proposed procedure offers a method of evaluation that is feasible, but still a very precise method, for the evaluation of electronic differential leukocyte counters. Following this abbreviated method, the classification of the leukocytes, from 5 x 20 unselected blood specimens, with a flow-cytometric analysis by the Sequoia Turner Cell-Dyn 3000, was compared with microscopic differential counts as the standard. With proven accuracy and good reproducibility, the Cell-Dyn 3000 is a good sieve for the selection of normal samples. The high sensitivity and fair specificity permits a reduction of the differential workload to about 30 percent of the normal workload.