Twenty-one subjects of which 5 sportsmen and 1 sport woman and the other 15 with osteoarthritis, undergoing orthopedic surgery, were consecutively recruited at Orthopedic Unit of our Hospital.
All clinical data [age, sex and body mass index (BMI) that was calculated according to the following formula: kg/m2] and the sonographic measurements of the 21 subjects were collected in an electronic database. Ethics approval (46/18OSS) was obtained from the Ethics Committee (Comitato Etico Campus Bio-Medico) of this University.
A unique operator, experienced in musculoskeletal sonography, conducted the examination basing on international indications and guidelines8,9,10,11,12,13. The regions of interest for this sonographic study were: the shoulder (supraspinatus), the wrist (median nerve), the hand (the flexor tendon of third finger), the knee (patellar tendon), the ankle (Achilles tendon).
Examinations were bilaterally performed in all 21 subjects both with a portable sonographic machine, the palmar “Arthrex Synergy” musculoskeletal (MSK) ultrasound linear scanner “AR-3501B-L7” by “Clarius” “Canada” (multifrequency 4–13 MHz, 167 mm high, 99 mm wide, 42 mm thick and weighing approximately 540 g) and with a high-end sonographic machine, the “General Electric (GE) Logiq E9 XD Clear” “USA”, that adopted a multifrequency (7–16 MHz) linear probe.
After launching a Clarius App for the palmar MSK ultrasound and creating a secure direct WI-Fi connection with iOS or Android mobile devices, the portable sonographic machine becomes almost instantly available to be used and real time images can be transmitted to the selected mobile device. Furthermore, the images can be wirelessly recorded to a secure Cloud site for reviewing and the storage. This palmar tool can be completely immersed in liquid, thanks to a magnesium shell coating and to the absence of cables, thus facilitating any disinfection procedure. A continued use is assured by a rechargeable battery quickly replaceable. A good depth (up to 7 cm) supplied by the scan, allows any kind of orthopedic study.
Preset musculoskeletal examination settings for the best optimization of the images are present in both sonographic machines.
The thickness of 42 tendons of each district (supraspinatus, flexor of the third finger, patellar and Achilles) and the cross sectional area of the 42 median nerves were sonographically assessed, in the same manner, with both sonographic machines (Figs 1A–D and 2A–D). Careful attention was placed to define the edges of tendons and of the median nerve, to obtain the best measurements possible of the tendon’s thickness and of the median nerve’s area. During the sonographic examination all patients were at rest and in a relaxed position without passive movements. To reduce the sampling errors linked to the compression of the median nerve and the tendons, the pressure exerted by the probe was minimized. The supraspinatus tendon, the median nerve and the flexor tendon of the third finger were examined with the patient in a seated position. Scanning of the supraspinatus tendon took place when the patient had the palm of the hands on the iliac crest and the elbow directed posteriorly; the maximum thickness of the supraspinatus tendon was measured scanning it in a long-axis view to 1.5 cm from the greater tuberosity of the humerus. Instead, median nerve and flexor tendon of the third finger were scanned with the arms extended on the couch with the palm of the hands upward. The cross sectional area of the median nerve was measured in an axial view, at the proximal inlet of the carpal tunnel at the level at which it was possible to recognize the most palmar point of the pisiform bone, using the direct tracing method with an electronic caliper; the thickness of the flexor tendon was assessed, in a longitudinal view, at the level of the mid part of the proximal phalanx of the third finger.
Figure 2An overview divided in Panels (A–D) of the measurements of the median nerve cross sectional area and of tendon thickness, using the high-end sonographic machine.
Full size image
During patellar tendon examination, the patient was in a recumbent position with the knees slightly bent, whereas the Achilles tendon was scanned with the patient laying prone and the gastrocnemius muscle relaxed.
In the patellar and Achilles tendons the thickness was measured in three points (proximal, mid an distal part) in a longitudinal view. Regarding the patellar tendon, the proximal and distal parts corresponded to the bottom pole of the patella and to the insertion of tibial tuberosity, respectively, while the mid part corresponded to the exact half of the same tendon. Instead, the proximal part of the Achilles tendon corresponded to a point 5 cm away from the calcaneus, the mid part to a point located in the exact half from the proximal and distal parts and the distal part to the point of tendon’s insertion of the calcaneus.
The mean value of all measurements from the right and left side was used for statistical evaluation. The time spent for each sonographic assessment was also taken to evaluate the feasibility.
Data were analysed by graphpad Software SPSS® version 22.0 (IBM Corporation, Chicago, IL, USA). Clinical data (i.e. age, BMI) were expressed as the mean ± SD. Two tail t Test was performed to analyse whether there were differences between the results obtained in any district by the two sonographic machines. Pearson’s rank coefficient was finally used to assess the presence or absence of the correlation between the measurements obtained by the two sonographic machines.
All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.
Informed consent was obtained from each subject. Ethics committee of this University approved the study.