In our cadaveric model of surgically created unstable DRUJ, reconstruction using the double suture button construct (transverse + oblique) restored the dorsal translation of the radius to baseline values. However, when the single (either transverse or oblique) was used, the dorsal translation returned to baseline only in the neutral position and did not fully normalize in pronation and supination. This suggests that the double-suture button construct offers superior stability compared to the single-suture button construct, particularly in pronation and supination. Our findings clearly demonstrate that the double-suture button construct provides optimal stability in cases of unstable DRUJ, confirming its superiority over the single-suture button construct.

The primary stabilizers of the DRUJ include the bone architecture of the sigmoid notch of the radius and the ulnar head, along with surrounding soft tissues [19]. The TFCC is the main soft tissue stabilizer, but when the TFCC is damaged or the ulna head is removed, the distal IOM becomes an important secondary stabilizer [11, 20, 21]. The strongest portion of the distal IOM, known as the DOB, originates near the proximal border of the pronator quadratus muscle and attaches to the dorsal rim of the ulnar notch [22, 23]. The prevalence of DOB ranges from 29 to 70%, and studies have shown that its presence significantly improves DRUJ stability [24, 25].

In a biomechanical study, Kitamura et al. found that DRUJ stability was greater in specimens with a DOB compared to those without it [20]. As a result, DOB reconstruction has garnered increasing attention, particularly in cases of chronic DRUJ instability. Recent biomechanical and clinical studies have underscored the importance of DOB reconstruction in enhancing DRUJ stability [13, 14, 16, 17, 26, 27]. Similarly, a recent systematic review has demonstrated that DOB reconstruction significantly enhances DRUJ stability, with improvements nearly equivalent to natural stability [28]. In line with these findings, Verbeek et al. reported favorable long-term outcomes in patients treated with DOB reinforcement, highlighting significant functional improvements and a relatively low failure rate at a median follow-up of 82 months [29].

In a study by de Vries et al., DRUJ instability was induced in five fresh-frozen cadaveric specimens, followed by DOB reconstruction with a single suture button construct [16]. Dorsal translation of the radius was measured in neutral, 45° pronation, and 45° supination using a custom testing device. After reconstruction, they found that the dorsal translation returned to baseline values across all positions [16].

In contrast, our study showed that dorsal translation in the unstable DRUJ reconstructed with a single suture button (transverse or oblique) only returned to baseline in the neutral position and not in the pronation and supination positions. This discrepancy may be due to differences in stabilization techniques. In our setup, the hand was secured to a circular external fixator using two perpendicular K-wires, allowing us to isolate the dorsal translation of the radius while keeping both the ulna and hand immobile. This arrangement minimized incorrect measurements by preventing dorsal hand translation.

Furthermore, our results demonstrated that using a double suture button construct (transverse + oblique) restored dorsal translation to baseline across all positions, suggesting it provides greater DRUJ stability compared to the single suture button construct (transverse or oblique).

In the study by de Vries et al., the mean dorsal translation in a stable DRUJ was 2.88 ± 0.77 mm in neutral, 1.59 ± 0.95 mm in pronation, and 2.42 ± 0.71 mm in supination [16]. For the unstable DRUJ, these values increased to 6.61 ± 0.60 mm in neutral, 2.74 ± 1.69 mm in pronation, and 4.56 ± 0.87 mm in supination [16]. After reconstruction with the single oblique suture button, the translation returned to 3.25 ± 0.77 mm in neutral, 1.48 ± 0.60 mm in pronation, and 2.80 ± 1.00 mm in supination [16]. The results from our study align with those of de Vries et al., though our measurements were slightly lower, possibly due to differences in our custom test system, which allowed isolated measurement of dorsal radius translation. Differences in cadaveric demographic characteristics, such as age and anatomical variations, may also have contributed to this slight variation.

As described above, de Vries et al. outlined a minimally invasive technique for stabilizing the DRUJ in cadaveric specimens using a percutaneous single-suture button construct placed along the DOB of the IOM [16]. Subsequently, Igbal et al. reported achieving DRUJ stability in a patient with chronic DRUJ instability using a similar approach and recommended it for both acute and chronic dislocations [27].

Liu et al. published results from a study of six patients treated with a single transverse suture button construct [30]. The researchers reported that this new suspension fixation method, using button plates for the surgical reconstruction of a DRUJ dislocation, was simple, minimally invasive, and provided DRUJ stability without requiring intra- or extra-articular ligament reconstruction [30]. Additionally, they observed that the method facilitated early functional exercise and resulted in satisfactory postoperative recovery [30].

Similarly, Kokly et al. reported the successful treatment of a patient with acute unstable DRUJ dislocation using a single transverse suture button construct for extra-articular stabilization [31]. In another case series, Hayward et al. successfully treated five patients with chronic DRUJ instability using the same single transverse suture button construct, demonstrating that this method offers a viable solution to a complex pathology [32].

Hsiao et al. treated three patients with acute DRUJ instability by placing a suture button construct along the direction of the DOB, achieving sufficient stability [33]. However, they recommended using a tendon allograft or a knotless suspension system due to complications with the suspension system, such as irritation from the knot plate and the inability to achieve adequate tension [33].

In patients with chronic DRUJ instability, TFCC repair is often not feasible, and TFCC reconstruction can be challenging due to the risk of ulnar head fracture during tunnel creation, particularly when accompanied by ulnar styloid fractures [13]. In such cases, DOB reconstruction using a single suture button construct may be performed [16]. However, in some chronic cases, subluxation may persist during pronation and supination [17]. In these cases, Satria et al. performed a second suture button construct perpendicular to the long axis of the ulna and radius, reporting full stability in all directions of the DRUJ [17]. Satria et al. emphasized that for chronic cases, a single suture button construct may not provide sufficient DRUJ stability, and additional distal radioulnar ligament with a second suture button construct is necessary [17].

The statistical results of our biomechanical study demonstrate that reconstructing an unstable DRUJ with double (transverse + oblique) suture button constructs significantly reduces dorsal translation in neutral, pronation, and supination positions, providing greater stability than reconstruction with a single (transverse or oblique) suture button construct. This suggests that double-suture button construct offers optimal stability for unstable DRUJ. In line with this, Rigó et al. found that newer techniques like the DX Swivelock provided superior initial stability compared to traditional methods, such as the Adams-Berger reconstruction [34]. This finding aligns with our results, where the double-suture button construct demonstrated enhanced stability and potential for early mobilization, highlighting the advantages of modern fixation techniques in restoring DRUJ function [34].

Additionally, the inclusion of effect sizes (Partial Eta Squared) provides a deeper understanding of the practical significance of our findings. While statistical significance confirms the existence of differences between groups, effect sizes quantify the magnitude of these differences, offering insights into their real-world relevance. The large effect sizes observed across all positions (neutral, pronation, and supination) suggest that the differences in dorsal translation between the double and single suture button constructs are not only statistically significant but also clinically meaningful. This highlights the potential of the double-suture button construct to offer more robust stability in clinical practice, contributing to better functional outcomes for patients with DRUJ instability. Future studies involving live subjects are needed to validate the practical benefits observed in this biomechanical model.

As de Vries et al. noted, while reconstructing an unstable DRUJ with a double suture button construct is minimally invasive, it can lead to complications [16]. Over-tightening the suture buttons may restrict wrist movement and increase pressure on the sigmoid notch. In addition, bone tunnel creation carries a risk of damaging the sensory branches of the ulnar and radial nerves, as well as causing fractures of the radial and ulnar. The risk of fracture is particularly high when using a double-suture button construct due to the proximity of the bone tunnels in the distal radius. Therefore, careful use of fluoroscopy during tunnel creation is critical to maintain at least a 1 cm distance between the tunnels in the distal radius. Furthermore, there is a theoretical risk of radioulnar synostosis as the tunnels pass between the radius and ulna [16]. Moreover, wear and tear over time may cause the buttons to break, necessitating their removal through minimally invasive incisions. Prominent knots on the ulnar side may also cause pain, which can be mitigated by using a knotless suture button construct.

The increased surface area of the double suture button construct may elevate the risk of implant irritation, which is a common concern in clinical practice. This trade-off between enhanced stability and the risk of irritation should be carefully considered when selecting the appropriate construct for each patient. While using a single construct may reduce irritation, further clinical studies are needed to confirm this without compromising joint stability [16].

In contrast to suture button constructs, tendon allograft techniques, such as those using the extensor carpi radialis longus (ECRL) or extensor carpi radialis brevis (ECRB) tendons, have been introduced as viable alternatives for DRUJ stabilization, particularly in cases where TFCC repair is not feasible or has failed [3, 8, 35]. The Adams procedure, which focuses on distal radioulnar ligament reconstruction using palmaris longus or ECRB tendon grafts, is another commonly employed technique with comparable functional outcomes [3, 8]. Although tendon allograft techniques offer the advantage of preserving soft tissue integrity and minimizing the risk of implant irritation, they are generally more invasive compared to suture button constructs. The suture button technique, being minimally invasive, provides the benefit of fewer complications related to soft tissue dissection [3, 8, 16]. Spies et al. demonstrated the long-term effectiveness of tendon grafts in the Adams procedure but also highlighted the associated complications [36]. In contrast, our study achieved similar stability using the double-suture button construct without the need for tendon harvesting, thereby reducing procedural invasiveness. Similarly, Tathe et al. described a novel technique for DRUJ reconstruction that avoided tendon graft morbidity, offering faster recovery and shorter operative times compared to traditional methods [37]. Nevertheless, further comparative studies between suture button constructs and tendon allograft methods, including the Adams procedure and DOB reconstructions, are necessary to fully evaluate their long-term efficacy in terms of stability, patient comfort, and minimizing complications.

While this study provides valuable biomechanical insights into the stabilization of the DRUJ using double suture button constructs, it is important to acknowledge the limitations of using cadaveric specimens. Cadaveric models allow for controlled testing environments but do not fully replicate the dynamic properties of living tissues, including muscle tone, healing capacity, and patient-specific variability. As such, the results presented here should be interpreted with caution when translating to clinical practice. Future studies should focus on validating these findings through in vivo models and clinical trials, where long-term stability, functional outcomes, and patient-reported pain levels can be assessed. These steps will be crucial for determining the true clinical efficacy of double suture button constructs in treating DRUJ instability.

This study has several limitations. First, as a cadaveric study, it lacks clinical data correlating the reduction in dorsal translation with patients’ clinical outcomes. Although the double-suture button construct significantly reduced dorsal translation in all three positions compared to the single-suture button construct, clinical studies are needed to determine the clinical relevance of these findings. Existing literature reports successful outcomes with the single-suture button construct in both acute and chronic DRUJ instability [27, 30,31,32,33]. Only one case report indicates that a second suture button was necessary to achieve sufficient stability [17]. It is essential to assess the adequacy of stability during surgery, and if needed, a second suture button may be a logical addition. Our study demonstrates that the double-suture button construct provides optimal stability, forming a basis for future clinical studies.

Another limitation is the relatively small sample size, which is often a constraint in cadaveric studies due to limited specimen availability. However, despite this limitation, our study was able to achieve statistically significant results that support the validity of our findings. Future studies with larger sample sizes would be beneficial in further confirming these results and enhancing the generalizability of the conclusions. Additionally, the advanced age of the cadaveric specimens and the use of both limbs in four of the five cadavers may have reduced variability in the results. However, this can be seen as a strength, as it eliminated anatomical differences and potentially increased the study’s power.

In our study, standardizing the force applied to the radius to measure dorsal translation and repeating each measurement three times minimized the potential for error, thereby strengthening our findings.