Normal Values of Distal Radioulnar Joint Kinematics during a Dynamic Press Test

Abstract

Background Measurement of in vivo distal radioulnar joint (DRUJ) pathomechanics during simple activities can represent the disability experienced by patients and may be useful in diagnostics of DRUJ instability. A first step is to describe the physiological normal limits for DRUJ kinematics in a reproducible and precise test setup, which was the aim of this study. Methods DRUJ kinematics were evaluated in 33 participants with dynamic radiostereometry (RSA) while performing a standardized press test examination. AutoRSA software was used for image analyses. Computed tomography (CT) forearm bone models were generated, and standardized anatomical axes were applied to estimate kinematic outcomes including, DRUJ translation, DRUJ position ratio, and changes in ulnar variance. Repeatability of dynamic RSA press test double examinations was evaluated to estimate the precision and intraclass correlation coefficient (ICC) test–retest agreement. Results The maximum force during the press test was 6.0 kg (95% confidence interval [CI]: 5.1–6.9), which resulted in 4.7 mm (95% CI: 4.2–5.1) DRUJ translation, DRUJ position ratio of 0.40 (95% CI: 0.33–0.44), and increase in ulnar variance of 1.1 mm (95% CI: 1.0–1.2). The mean maximum DRUJ translation leveled off after a 5 kg force application. The DRUJ translation ICC coefficient was 0.93 within a prediction interval of ± 0.53mm. Conclusions This clinical study demonstrates the normal values of DRUJ kinematics and reports excellent agreement and high precision of the press tests examination using an automated noninvasive dynamic RSA imaging method based on patient-specific CT bone models. The next step is the application of the method in patients with arthroscopic verified triangular fibrocartilage complex injuries. Level of Evidence This is a Level IV, case series study.

Distal radioulnar joint kinematics before surgery and 12 months following open foveal reinsertion of the triangular fibrocartilage complex: comparison with the contralateral non-injured joint

“…All 21 patients were investigated preoperatively with conventional wrist radiographs of the injured wrist. Bilateral CT scans of the forearm were used to generate individualized 3D bone-volume models and surface models of the radius and ulna by segmentation (Kitware, New York, USA) (5). The 3D bone models were used for simulation of 2D digital reconstructed radiographs (DRR) and analysis of dRSA recordings.…”

“…The 3D bone models were used for simulation of 2D digital reconstructed radiographs (DRR) and analysis of dRSA recordings. This enables in vivo estimation of joint kinematics using anatomical landmarks and axes (Figure 1) (5). Preoperative MRI of the patient's symptomatic wrist was performed for evaluation of (i) foveal TFCC tear (positive), (ii) no tear detected but abnormal "signal" with peripheral edema (uncertain), and (iii) other competing injuries by an experienced consultant radiologist (KBP).…”

“…A custom-made weight platform recorded the applied force (kg) during a standardized press test performed by the patients, as related dRSA images were recorded digitally at an image rate of 10 Hz (Adora RSA system, NRT X-Ray, Hasselager, Denmark) (Figure 2) (5). We conducted preoperative bilateral press test double examinations to test the dRSA repeatability.…”

“…tion in the calibration box coordinate system, which was later transformed into individual anatomical coordinate systems of the radius and ulna defined from anatomical landmarks on the individual 3D bone-surface models (5).…”

“…Imaging modalities such as CT have poor agreement with clinical examination (3) and MRI has limited sensitivity and specificity for visualizing TFCC lesions (4). We recently validated a non-invasive highly precise dynamic radiostereometry (dRSA) imaging method for objective measurement of DRUJ kinematics and instability in vivo (5). Foveal TFCC lesions can be treated surgically by open or arthroscopic reinsertion, with similar postoperative results evaluated clinically at follow-up by a radioulnar stress test (i.e., the Ballottement test) (6,7).…”