Metacarpophalangeal Joint

The initial step, performed during a 2-day exercise, aimed at evaluating intraobserver and interobserver reliability for scoring static images and scoring images acquired in real-time while scanning patients.
Reading static images (day 1). Static images, representing a broad range of different degrees of synovitis in the metacarpophalangeal (MCP), wrist, proximal interphalangeal (PIP) and metatarsophalangeal joints (MTP) of patients with RA attending the Rheumatology Department of Ambroise Paré Hospital in Boulogne-Billancourt (France) were anonymised by the convenor (MADA). Images were obtained using the preliminary OMERACT definition for synovitis which includes both GS (SH and effusion) and PD findings. Images were acquired according to the EULAR recommendations16 (link) with a longitudinal scan obtained using either a dorsal or volar (plantar) view. Seventeen musculoskeletal sonographers (from Denmark, France, Germany, Hungary, Ireland, Italy, Netherlands, Spain, UK and USA) simultaneously but independently scored the images, which were presented randomly presented with 60 s for evaluating each image. No patient information was made available. Participants were asked to score GS and PD using both a binary (presence/absence) and SQ grading from 0 to 3 (normal, minimal, moderate, severe), according to their own daily practice, on a preprinted data collection sheet.
Acquiring and reading images (day 2). A practical exercise was then conducted the following day scanning and scoring synovitis. Eight patients with RA17 (link) were recruited from the same Rheumatology Department each having only mild to moderate hand deformities in order to eliminate possible acquisition difficulties due to severe structural deformities including ankylosis. The study was conducted in accordance with the Declaration of Helsinki and each participant gave written informed consent. The examinations were performed on the same day, in the same room, using eight identical machines (Technos MPX - Esaote Biomedica, Genoa, Italy) equipped with a 10–14 MHz broadband linear array transducer. The machines were calibrated with identical Doppler settings (frequency of 10.1 MHz, pulse repetition frequency of 750 Hz and Doppler gain of 50–53 dB). In this way, the impact of machines on the results was minimised. Fourteen rheumatologists who participated on the first day, in step 1, participated on the second day; all were blinded to the clinical details of the patients (ie, presence or not of active disease). Each patient was assigned to one machine and the sonographers then rotated from one machine to the next in a predefined sequence with 10 min allocated for scanning and recording the findings on a standard score sheet. In each patient, the second to fifth MCP and second to fifth PIP joints were scanned bilaterally using a GS and PD longitudinal scan in the midline of the joint on both the dorsal and volar aspects. Sixteen MCP joints were scanned twice in order to assess the intraobserver reliability.

Subjects’ Monofilament and Two-Point Discrimination scores for the index and thumb fingertips were compared with and without noise. Specifically, sensory scores without noise were recorded at the beginning (pre) and end (post) of the testing session. Sensory scores for the pre and post test were compared to ensure no learning effect and no residual effect of noise after the exposure during the one day testing session. In between the pre and post sensory tests without noise, sensory scores with noise were recorded while subthreshold vibrotactile noise was applied to four different locations at three noise intensities. The subthreshold vibrotactile noise was turned on immediately before each sensory test and was turned off immediately after each sensory test (lasting approximately 1 minute each). The testing session lasted for approximately two hours for each subject.
Subthreshold vibrotactile noise was white noise bandwidth filtered at 0 to 500 Hz, applied with a C-3 Tactor (Engineering Acoustics, Inc. Casselberry, Florida). Due to the characteristics of the C-3 Tactor, the vibration amplitude could have been larger for 100-300 Hz which includes the sensitive range of the Pacinian corpuscles. The noise was applied to one of four locations in the paretic upper limb (Figure 1): 1) dorsal hand approximately 2 cm proximal to the index finger knuckle; 2) dorsal hand approximately 2 cm proximal to the thumb knuckle; 3) dorsal wrist, medial to the radial styloid process; and 4) volar wrist, medial to the radial styloid process. These locations were arbitrarily chosen with the intention of developing a future wearable rehabilitation device for stroke survivors. Since the long-term goal of the research is to improve dexterity and grip control, noise locations that would interfere with gripping, such as the fingertip or palm, were avoided. Presentation of noise locations was block randomized.
Noise intensities were set to 40%, 60%, or 80% of the sensory thresholds specific for each location. The order of testing different noise intensities was randomized within each location block. To determine the sensory threshold, the noise intensity was increased and decreased until the subject was barely able to distinguish between an “off” and an “on” presentation of the vibrotactile noise (i.e., the method of ascending and descending limits [22 (link)]). Subjects’ mean sensory threshold occurred when the Tactor was driven by current of 0.17 A peak-to-peak (Table 1). There is a linear relationship between the current and amplitude of the vibration. According to the data sheet from the manufacturer, 0.17 A peak-to-peak corresponds to a maximum amplitude of 260 μm. Subthreshold noise intensities were chosen not only so that subjects could not distinguish between trials with and without noise [21 (link)], but also because suprathreshold noise has been shown to degrade performance [23 (link)].
The Monofilament and Two-Point Discrimination Tests were administered using standard testing measures. For the Monofilament score, beginning with the baseline 2.83 Monofilament (indicating the threshold for “normal sensing”), the Monofilament was applied to the fingertip at least three times and the smallest Monofilament for which the subjects responded “yes” and could identify the correct finger that was touched marked the score [29 ]. The Two-Point Discrimination test was conducted so that subjects were asked to respond either “one” for a single point and “two” for two points separated by a small distance [29 ]. One and two point stimuli were alternated randomly. The smallest distance where the subjects responded correctly three consecutive times to identifying two separated points was used for their Two-Point Discrimination score. A score of 2.83 [30 ] and 5 mm [31 (link)] was considered normal for the Monofilament test and Two-Point Discrimination tests, respectively.

In order to quantify upper limb tremor for comparison, we collected two continuous tremor signals, which were tremor acceleration and EMG signals, respectively. Before experiment, the tremor type (postural tremor/resting tremor) to record of each subject was decided independently by a physician after patient's enrollment. The main principle of choosing the main tremor type is tremor intensity and stability. Intentional tremor was not considered in our research since it is difficult to standardize motion. For subjects whose main tremor type is resting tremor, we had them seated comfortably with arms fully supported on armrests and recorded their tremor. For the others, postural tremor was inspected with seated subject stretching the whole upper limb forward and maintaining the posture for some time (Zhang et al., 2018 (link)). Additional requirements in recording postural tremor included: (1) fingers closed, (2) palms facing downward, and (3) seated upright.
All data was recorded through a commercial device system named the Biometrics Datalog (Biometrics Inc., the USA), along with a three-axis accelerometer sensor and four surface EMG (sEMG) sensors. The accelerometer sensor was fixed onto the third knuckle of the middle finger on the more affected side. Four sEMG sensors were attached respectively onto the muscle bellies of the flexor carpi radialis (FCR), the flexor carpi ulnaris (FCU), the extensor carpi radialis (ECR) and the extensor carpi ulnaris (ECU). The data of tremor acceleration and EMG signals were both digitized into 1,000 Hz and simultaneously recorded. From each subject, we obtained a 5-min sequential data package comprising tremor acceleration and EMG signals.

This study was performed in accordance with the Declaration of Helsinki and was approved by the Ethics Committee of Children’s Hospital of Nanjing Medical University (Approval number: 202205087-1). The informed consent was obtained from the parents/guardians of all participants. Patients with Benson type 1 camptodactyly treated in our institute between January 2019 and January 2021 were retrospectively analyzed. The inclusion criteria involved (1) 5th digit flexion deformity present at birth, (2) age > 1 year, and (3) moderate-to-severe deformity. The exclusion criteria involved (1) Benson types II and III camptodactyly, (2) camptodactyly in association with a syndrome, and (3) acquired camptodactyly.
A total of 12 digits (5 on the right and 7 on the left) in 8 patients (7 male and 1 female) were involved. The mean age was 4.9 years (range 1–11 years). Among them, 3 digits were previously treated conservatively. Camptodactyly was determined using the Bouvier maneuver, which involved extending the PIP joint while flexing the metacarpophalangeal joint to assess for contracture of the flexor digitorum superficialis tendon. The mean total passive motion (TPM) was 32.5°. And total active motion (TAM) of the PIP joint was 22°.

Participants will undergo imaging by MSUS at baseline and 4, 12, 24, 36, and 52 weeks performed by one of the JCR-certified sonographers. A systematic multiplanar grayscale (GS) and power Doppler (PD) examination of each patient’s joints will be performed using a multifrequency linear transducer (12–24 MHz). Depending on which Doppler modality is the most sensitive on the individual machines, PD will be used. The Doppler settings will be adjusted at each hospital according to published recommendations [21 (link)]. During the study, no change in MSUS settings and no software upgrading will occur.
Articular synovitis will be assessed by MSUS on dorsal views of 22 joints: bilateral wrist joints, 1st–5th metacarpophalangeal joints, interphalangeal joints, and 2nd–5th proximal interphalangeal joints. GS grade semiquantitatively scores the degree of synovial hypertrophy of each joint as within normal limits (grade 0), minimal (grade 1), moderate (grade 2), or severe (grade 3). In addition, PD grade semiquantitatively scores the degree of synovial PD signal of each joint as within the normal range (grade 0), minimal (grade 1), moderate (grade 2), and severe (grade 3) [22 (link), 23 (link)]. The sum of the GS or PD scores is considered to be the total GS or PD scores, respectively. We will also assess the Outcome Measures in Rheumatology (OMERACT)-EULAR combined PDUS score (i.e., the combined PD score) and Global OMERACT-EULAR Synovitis Score [22 (link), 23 (link)]. The combined PD score is combined with synovial hypertrophy shown by GS and PD [22 (link), 23 (link)].