Validity and reliability of a novel 3D ultrasound approach to assess static lengths and the lengthening behavior of the gastrocnemius medialis muscle and the Achilles tendon in vivo.

PURPOSE: Human muscle-tendon units (MTUs) are highly plastic and undergo changes in response to specific diseases and disorders. To investigate the pathological changes and the effects of therapeutic treatments, the use of valid and reliable examination methods is of crucial importance. Therefore, in this study, a simple 3D ultrasound approach was developed and evaluated with regard to: (1) its validity in comparison to magnetic resonance imaging (MRI) for the assessment of the gastrocnemius medialis (GM) MTU, muscle belly, and Achilles tendon lengths; and (2) its reliability for static and dynamic length measurements. METHODS: Sixteen participants were included in the study. To evaluate the validity and reliability of the novel 3D ultrasound approach, two ultrasound measurement sessions and one MRI assessment were performed. By combining 2D ultrasound and 3D motion capture, the tissue lengths were assessed at a fixed ankle joint position and compared to the MRI measurements using Bland-Altman plots. The intra-rater and inter-rater reliability for the static and dynamic length assessments was determined using the coefficient of variation, standard error of measurement (SEM), minimal detectable change (MDC95), and intraclass correlation coefficient (ICC). RESULTS: The 3D ultrasound approach slightly underestimated the length when compared with MRI by 0.7%, 1.5%, and 1.1% for the GM muscle belly, Achilles tendon, and MTU, respectively. The approach showed excellent intra-rater as well as inter-rater reliability, with high ICC (≥ 0.94), small SEM (≤ 1.3 mm), and good MDC95 (≤ 3.6 mm) values, with even better reliability found for the static length measurements. CONCLUSION: The proposed 3D ultrasound approach was found to be valid and reliable for the assessment of the GM MTU, muscle belly, and Achilles tendon lengths, as well as the tissue lengthening behavior, confirming its potential as a useful tool for investigating the effects of training interventions or therapeutic treatments (e.g., surgery or conservative treatments such as stretching and orthotics). LEVEL OF EVIDENCE: Level II.

PFA-100 closure times in preoperative screening in 500 pediatric patients.

Three to five percent of patients undergoing surgery have either an acquired or congenital platelet defect or von Willebrand disease (vWD). The predictive value of preoperative coagulation screening is questionable. PFA-100 is now routinely used in preoperative screening in our pediatric outpatient service. We wanted to assess whether the PFA-100 would help to identify patients with primary haemostatic defects or if the additional use of PFA-100 would add to the problem of unnecessary pathologic preoperative laboratory values resulting in delay of surgical procedure. We investigated 500 children consecutively seen in our outpatient service before surgery. Blood cell count, aPTT, PFA-100 closure times (CT) were done in all patients. If abnormalities were found, the patient was presented to a haemostatic expert. vWF:AG, R:Cof and factor VIII were analysed in all patients with prolonged closure times and APTT values. One hundred twenty-six patients (25.2%) showed abnormalities in APTT and/or PFA-100. Further investigations in 89 of these 126 patients did not yield a specific diagnosis; neither diagnostic criteria for impaired haemostasis were found by questionnaire. None of these 89 patients had a bleeding complication during surgery. Forty-eight patients showed prolonged CTs. Twelve patients with low vWF:AG were detected, 10 of these patients were found by PFA-100. Four of these patients did present with normal APTT values. Our study shows that similar to the APTT the PFA-100 is probably only a good screening method when a haemostatic defect in a patient is clinically likely, especially to screen forVWD, and the test should not be used in general unselective screening.