Artificial Intelligence-Enhanced Quantitative 3D Analysis of Distal Radioulnar Ligament Insertion Footprints of the Triangular Fibrocartilage Complex With Interactive Validation.

Purpose: To determine the value of an anatomic distal radio-ulnar joint ligament reconstruction (Adam's technique) in patients who suffer chronic pain related to distal radio-ulnar joint instability. Materials and Methods: Twelve patients who suffered from chronic pain related to distal radio-ulnar instability and underwent a reconstruction of the distal radio-ulnar ligament using a free tendon technique were enrolled in this study. The mean follow up period was at least 1 year. In all cases, injury to the distal radio-ulnar joint was present, which had been previously treated with conservatively. There was no evidence of arthritis on the distal radio-ulnar joint radiologically. The radiological radio-ulnar space and displacement of the ulnar head, clinical pain, stability, the range of motion and the grip power were measured before and after surgery (follow up 1 year). Results: No displacement of the distal radio-ulnar joint or prominence of the ulnar head was observed radiologically in 10 cases, and only partial subluxation was present in 2 cases. Clinically, the pain disappeared in 8 cases and the stability of the joint was recovered in 8. The mean pronation, supination range and grip power increased by an average of 73, 71 degrees and 11.7 kg, respectively. Conclusion: In treating distal radio-ulnar joint instability related to chronic pain, Adam's technique using palmaris longus, which is an operation using a single incision, and by restoring the distal radio-ulnar ligament anatomically can decrease the level of pain and recover the range of motion. Therefore, it is a good method worth considering in this situation.

II.

To identify the subluxation degrees of extensor carpi ulnaris (ECU) tendon on neutral wrist MRI in patients with ulnar-sided wrist pain and to evaluate the relationships of ECU subluxation with accompanying imaging findings such as ECU tenosynovitis, distal radioulnar joint (DRUJ) stability, and triangular fibrocartilage complex (TFCC) pathology. A total of 297 MRIs of 292 patients having ulnar side pain were reviewed retrospectively. Degrees of ECU subluxation was classified into four grades: grade 0, no subluxation; grade 1, tendon displacement < 50% of the tendon width; grade 2, tendon displacement 51 to 99% of the tendon width; and grade 3, tendon displacement of 100% of the tendon width. ECU tenosynovitis, ECU tendinosis, injuries of triangular fibrocartilage and distal radioulnar ligaments (DRUL), translation ratio of the DRUJ, rotation angle of the DRUJ, and the width, depth, and length of the ulnar groove were assessed on wrist MRI. The relationships between degree of ECU subluxation and these imaging findings were investigated. Women had higher subluxation degrees of the ECU tendon (p = 0.001). Tenosynovitis of the ECU, sprain of the dorsal DRUL, dorsovolar translation ratio and rotation angle of the DRUJ, and depth and length of the ulnar groove were statistically significantly related to the subluxation degree of the ECU tendon (p = 0.000). High-grade subluxation of the ECU tendon was strongly correlated with ECU tenosynovitis and DRUJ translation. Clinicians and radiologists should scrutinize imaging findings, particularly when patients with ulnar-sided wrist pain have high-grade subluxation of the ECU tendon.

The distal radioulnar joint (DRUJ) is the distal articulation between the radius and ulna, acting as a major weight-bearing joint at the wrist and distributing forces across the forearm bones. The articulating surfaces are the radial sigmoid notch and ulnar head, while the ulnar fovea serves as a critical attachment site for multiple capsuloligamentous structures. The DRUJ is an inherently unstable joint, relying heavily on intrinsic and extrinsic soft-tissue stabilizers. The triangular fibrocartilage complex (TFCC) is the chief stabilizer, composed of the central disk, distal radioulnar ligaments, ulnocarpal ligaments, extensor carpi ulnaris tendon subsheath, and ulnomeniscal homologue. TFCC lesions are traditionally classified into traumatic or degenerative on the basis of the Palmer classification. The novel Atzei classification is promising, correlating clinical, radiologic, and arthroscopic findings while providing a therapeutic algorithm. The interosseous membrane and pronator quadratus are extrinsic stabilizers that offer a minor contribution to the joint's stability in conjunction with the joints of the wrist and elbow. Traumatic and overuse or degenerative disorders are the most common causes of DRUJ dysfunction, although inflammatory and developmental abnormalities also occur. Radiography and CT are used to evaluate the integrity of the osseous constituents and joint alignment. US is a useful screening tool for synovitis in the setting of TFCC tears and offers dynamic capabilities for detecting tendon instability. MRI allows simultaneous osseous and soft-tissue evaluation and is not operator dependent. Arthrographic CT or MRI provides a more detailed assessment of the TFCC, which aids in treatment and surgical decision making. The authors review the pertinent anatomy and imaging considerations and illustrate common disorders affecting the DRUJ. Online supplemental material is available for this article. © RSNA, 2022.

Extensor Carpi Ulnaris “Turn Around” Ligamentoplasty For Distal Radioulnar Joint Instability

Objective: To evaluate the reliability and accuracy of magnetic resonance imaging (MRI) on describing the structure of triangular fibrocartilage complex (TFCC) in 7 cadavers with autopsy being the golden standard. Methods: In total, 7 healthy cadavers were included (4 males, 3 females, the average age was 51 years). All cadavers were preserved under -30 ℃ condition and thawed out before the experiment. The autopsy was performed by the same group of hand surgeons immediately after the MRI examination (3.0 tesla, wrist coil,"superman"position). The integrity of triangular fibrocartilage (TFC), proximal component/distal component of distal radioulnar ligament (DRUL), ulnocarpal ligament (UCL) was evaluated, and the thickness of central portion of TFC was measured during the autopsy. The sensitivity, specificity, positive/negative predictive value (PPV/NPV) and positive/negative likelihood ratio (PLR/NLR) of MRI were calculated. The intraclass correlation coefficient (ICC) was calculated between the thickness of central portion of TFC on MRI and autopsy results. Results: With autopsy being the golden standard, the ICC of MRI= 0.838 (95%CI: 0.33-0.97, P<0.01). In evaluating the condition of central portion of TFC by MRI, sensitivity= 1, specificity=1, PLR=+∞, NLR=0. In evaluating the condition of proximal component/distal component of DRUL by MRI, sensitivity=1, specificity=0.83, PLR=6, NLR=0. The sensitivity, specificity, PPV, NPV, PLR, NLR of integrity of UCL in MRI was 0.33, 0.75, 0.50, 0.75, 1.33, 0.89, respectively. Conclusion: The 3.0T MRI can be a useful tool in diagnosis of the injury of TFC and proximal/distal component of DRUL, as it has a good description of TFCC's subtle structure.

This study aimed to investigate the optimal tension for the reconstruction of the distal radioulnar ligaments (DRULs) in the treatment of the distal radioulnar joint (DRUJ) instability. A total of eight human cadaver upper extremities were used. First, the Tekscan sensor film system was used to measure the contact characteristics of the intact DRUJ. Following this, the DRULs were resected, and the measurement was repeated. The DRULs were then reconstructed according to Adams' procedure, and the contact forces under different initial tension were compared with that of the intact group to obtain the optimal tension. At that point, the contact force of the DRUJ was close to normal. The reliability of the obtained tension was verified by translational testing, which reflected the stability of the DRUJ. In the neutral position, the contact force, area, and pressure inside DRUJ were 0.51 ± 0.10N, 64.08 ± 11.58 mm2, and 8.33 ± 2.42kPa, respectively. After the DRULs were resected, they were 0.19 ± 0.02N, 41.75 ± 5.01 mm2, and 4.86 ± 1.06kPa, respectively. The relationship between the tension and contact force was linear regression (Y = 0.0496x + 0.229, R2 = 0.9575, P < 0.0001). According to the equation, when the tension was 3.64-7.68N, the contact force was close to normal. There was no statistical difference in the stability of the reconstructed DRUJ under this tension compared with the intact group (P = 0.08). By comparing the contact forces under different reconstruction tensions with the normal value, we obtained the optimal tension, which can provide the theoretical basis for the clinical treatment of chronic DRUJ instability.

Arthroscopic TFCC Ulnar Bone Tunnel Foveal Repair in Adult Patients

This study was designed to investigate the length changes of the distal radioulnar ligament at different wrist positions and to determine the effect of hyperextension on the distal radioulnar ligament and to find out the most vulnerable position where the distal radioulnar ligament rupture and foveal avulsion. We obtained computed tomography scans of the wrists for 12 volunteers including two groups: hyperextension group and hyperextension with maximal rotation group. The images were reconstructed to the three-dimensional bone structures with customized software. The four portions of the distal radioulnar ligament were measured and analyzed statistically. No significant differences were noted in the lengths of the each portion of the distal radioulnar ligament among neutral position, wrist hyperextension, and hyper-radial extension. From neutral position to hyperextension with maximal pronation, the lengths of the palmar superficial radioulnar ligament (psRU) and dorsal deep radioulnar ligament (ddRU) decreased significantly, whereas the dorsal superficial radioulnar ligaments (dsRU) and palmar deep radioulnar ligament (pdRU) increased significantly. From neutral position to hyperextension with maximal supination, the lengths of the pdRU and dsRU ligaments decreased significantly, and the lengths of psRU and ddRU ligaments changed little. The factor of hyperextension has little effect on the length of the distal radioulnar ligament and the distal radioulnar ligament may be under great tension at the position of hyperextension with maximal pronation. These findings can provide more information to understand the pathomechanics of the triangular fibrocartilage complex injury caused by a fall on the outstretched hand and can provide information relevant to the distal radioulnar ligament restoration.

the distal radioulnar joint as a load-bearing mechanism—a biomechanical study

Distal radio-ulnar ligament motion during supination and pronation

Introduction: The triangular fibrocartilage complex (TFCC) is a ligamentous and cartilaginous structure that suspends the distal radius and the ulnar carpus from the distal ulna. It consists of a triangular fibrocartilage disc, radioulnar ligaments (RUL) and ulnocarpal ligaments (UCL) and is considered the main stabilizer of the distal radioulnar joint. The etiology of TFCC injuries consists of falls onto pronated hyperextended wrist, forced rotational movements or they are in association with distal forearm fractures. Patients report trauma followed by ulnar-side wrist pain, swelling, sound of clicking during supination or pronation and later on - loss of grip strength. Two specific classifications are used. The Palmer classification gives accurate anatomical location of the lesion while the five-graded Atzei-EWAS classification is used to determine the severity of the rupture. Stabilization of the distal radioulnar joint with reconstruction of distal radioulnar ligaments as outlined by Adams is indicated if a refixation of the triangular fibrocartilage complex is no longer possible and there are no present arthrotic changes. Materials and Methods: Ten patients with distal radioulnar joint instability caused by 4 th grade TFCC tears were diagnosed and admitted to the Clinic of Orthopedics and Traumatology in St. Anna University Hospital, Varna for the interval 2013-2017. The procedure of Adams was the surgical method of choice for all of them. Results: MAYO wrist score was used for evaluation of the patients` pre- and postoperative conditions. The results showed restored stability, relieved symptoms and attained near-physiological levels of pronation and supination after the surgical procedure. Conclusion: TFCC injuries are not to be treated lightly as they trouble the mechanics of the DRUJ. Surgical treatment is considered superior to the conservative, and the Adams procedure is an effective method of approach towards the 4 th grade tears.

Background This study created an anatomic reconstruction of the distal oblique bundle (DOB) of the interosseous membrane to determine its effect on distal radioulnar joint (DRUJ) instability and compare this technique with distal radioulnar ligament (DRUL) reconstruction. Questions/Purposes We hypothesized that this reconstruction would provide equivalent stability to DRUL reconstruction and that combining the two techniques would enhance stability. Methods Six cadaveric upper limbs were affixed to a custom frame. The volar/dorsal translation of the radius relative to the ulna was measured in 60° pronation, neutral, and 60° supination. Translation was sequentially measured with the DRUJ intact, with sectioned DRULs and triangular fibrocartilaginous complex (TFCC), and with sectioned DOBs. Reconstructions were performed on the DRULs, on the DOB tensioned in both neutral and supination, and employing both techniques. Results The DOB reconstruction, tensioned both in the neutral position and in 60° supination, was more stable than the partial and complete instability in 6/6 specimens in pronation and the neutral position and in 5/6 specimens in supination. The DOB reconstruction and the DOB reconstruction tensioned in supination were more stable than the DRUL reconstruction in 4/6 patients. Combining the two techniques did not further reduce translation. Conclusions The DOB reconstruction is capable of improving stability in the unstable DRUJ.

PurposeSymptomatic instability of the distal radioulnar joint (DRUJ) caused by lesion of the Triangular Fibrocartilage Complex (TFCC) can be treated with a number of surgical techniques. Clinical examination of DRUJ translation is subjective and limited by inter-observer variability.The aim of this study was to compare the stabilizing effect on DRUJ translation with two different surgical methods using the Piano-key test and a new precise low-dose, non-invasive radiostereometric imaging method (AutoRSA).MethodsIn a randomized experimental study we evaluated the DRUJ translation in ten human cadaver arms (8 males, mean age 78 years) after cutting the proximal and distal TFCC insertions, and after open surgical TFCC reinsertion (n = 5) or TFCC reconstruction using a palmaris longus tendon graft ad modum Adams (n = 5).The cadaver arms were mounted in a custom-made fixture for a standardized Piano-key test. Radiostereometric images were recorded and AutoRSA software was used for image analyses. Standardised anatomical axes and coordinate systems of the forearm computer tomography bone models were applied to estimate DRUJ translation after TFCC lesions and after surgical repair.ResultsThe DRUJ translation after cutting the proximal and distal TFCC insertions was 2.48 mm (95% CI 1.61; 3.36). Foveal TFCC reinsertion reduced DRUJ translation by 1.78 mm (95% CI 0.82; 2.74, p = 0.007), while TFCC reconstruction reduced DRUJ translation by 1.01 mm (95% CI -1.58; 3.60, p = 0.17).ConclusionIn conclusion, foveal TFCC reinsertion significantly decreased DRUJ translation while the stabilizing effect of Adams TFCC reconstruction was heterogeneous. This supports the clinical recommendation of TFCC reinsertion in patients suffering from symptomatic DRUJ instability due to acute fovea TFCC lesions.

The deep portion of the distal radioulnar ligaments (DRUL) inserts on the ulnar fovea and is the most important stabilizer of the distal radioulnar joint (DRUJ). Ulnar styloid base fractures that include the ulnar fovea may cause DRUJ instability. DRUJ stability in pronosupination was evaluated in 12 fresh-frozen upper extremities (4 female) aged 52 to 68 years (mean: 58.8 years) using a custom fixture, which allowed free rotation of the radius around the fixed ulna. Optical motion capture was used to record rotation of the radius with respect to the ulna. Each specimen was subjected to 3 N m of torque in both supination and pronation under 4 conditions: intact, ulnar styloid osteotomy with disruption of the foveal insertion of the DRUL, ulnar styloid fixation, and DRUL transection. Group differences were compared using a 1-way repeated-measures analysis of variance and Tukey multiple comparison post hoc tests. When compared with the intact condition, both ulnar styloid osteotomy and DRUL transection significantly increased mean pronation (by 9.40° and 15.21°, respectively) and supination (by 9.05° and 17.42°, respectively) of the forearm. Screw fixation only significantly reduced pronation compared with osteotomy (by 2.62°). Screw fixation did not significantly affect supination. Ulnar styloid fractures that disrupt the fovea cause instability of the DRUJ in pronation and supination under 3 N m of torque in a cadaveric model. Screw fixation of ulnar styloid base fractures achieves anatomic reduction; however, it only partially returns rotational stability acutely to the DRUJ and only during pronation.