Distal Radioulnar Joint Stability Research Articles

The Contribution of the Distal Oblique Band to Distal Radioulnar Joint Stability

The distal radioulnar joint (DRUJ) is supported by an array of dynamic and static stabilizers, of which the triangular fibrocartilage complex (TFCC) is the most important, and the distal interosseous ligament is next in importance. The distal oblique band (DOB) is an identifiable component of the distal interosseous ligament, found in a subset of the population. Our objective was to determine the contribution of the DOB to DRUJ stability in the presence of a disrupted TFCC. Twenty-three above-elbow specimens were prepared by removing the TFCC and the DRUJ joint capsule, preserving the distal interosseous ligament and the pronator quadratus. Cadavers were stratified into two groups-those with, and those without a DOB. A bone plate and screws were attached to the ulna; then, a transverse load was applied to failure, creating a diastasis between the radius and ulna. The group with a DOB had a mean load at failure of 160.7 ± 46.5 N. The group without a DOB had a mean load at failure of 148.0 ± 26.3 N. Stiffness prior to failure was 16.9 N/mm in the group with a DOB and 12.4 N/mm in the group without a DOB. The current results indicate that the DOB may not substantially contribute to DRUJ stability in the presence of a disrupted TFCC. Stability of the DRUJ after TFCC injury may not be substantially improved by the presence of a DOB. Thus, the clinical importance of DOB reconstruction remains unclear.

Current concepts and new trends in management of isolated triangular fibrocartilage complex injuries.

The triangular fibrocartilaginous complex is made of multiple components, of which the palmar and dorsal radioulnar ligaments play an important role in distal radioulnar joint stability. The ulnar wrist ligaments may be injured during forearm and wrist trauma. There are several aspects of triangular fibrocartilaginous complex management that are still open to debate. The aim of the present study was to review the current concepts and discuss emerging trends to better elucidate and treat this important ligament complex.Level of evidence: V.

The role of arthroscopic triangular fibrocartilage complex repair in a case of bilateral Galeazzi fracture-dislocation

This report presents the case of a 23-year-old man with bilateral distal one-third radial shaft fractures and associated distal radioulnar joint disruption, known as Galeazzi fractures, resulting from a fall from a kickboard. After open reduction and plate internal fixation for both radial shafts, the radioulnar joints remained unstable on both sides. We performed arthroscopic repair of the triangular fibrocartilage complex on the left side and used a short arm splint to immobilize the right side. At the 6-month postoperative follow-up, the patient reported mild stiffness in the left wrist, although both sides showed a full range of motion and distal radioulnar joint stability. In conclusion, when achieving anatomic reduction and stable fixation of the radial shaft in a Galeazzi fracture, favorable results can be achieved without additional surgical treatment, even if the distal radioulnar joint is unstable during surgery.

Headless screw fixation of unstable ulnar styloid base fractures after distal radial fractures fixation

Ulnar styloid fractures occur frequently concomitant with distal radial fractures. Although unstable distal radial fractures are mostly surgically treated, ulnar styloid fractures are often ignored. Unstable fractures at the base of the ulnar styloid may lead to persistent ulnar pain, due to distal radioulnar joint instability or ulnar styloid non-union.We retrospectively analyzed a single-surgeon cohort series of surgically treated distal radial fractures on how these concomitant ulnar styloid fractures were regarded: indications for surgery and surgical technique with headless screw fixation.119 surgically treated distal radial fractures were assessed. 51 (42.8%) of the surgically treated distal radial fractures had a distal ulnar fracture, and more specifically 23 (19.3%) had a base fracture of the ulnar styloid. 9 (7.6%) of the wrists had a base fracture of the ulnar styloid which was considered after distal radial fracture fixation as persistently unstable, during distal radioulnar joint ballottement translation test. This fracture subtype was immediately treated with headless screw fixation, resulting in all cases in bony union, with a mean active pronation of 85°, a mean active supination of 80° and a clinical stable distal radioulnar joint, with minimal ulnar pain after 6 weeks (mean Visual Analogue Scale 1). After at least 12 months, persistent pain did not occur and mean QuickDASH was 2.5.According to this single-surgeon cohort series, headless screw fixation provides a reliable treatment for unstable base fractures of the ulnar styloid after distal radial fixation.

Dynamic Computed Tomography of the Distal Radioulnar Joint Versus Magnetic Resonance Imaging in Detecting Foveal Tears of the Triangular Fibrocartilage Complex.

Diagnosis of foveal triangular fibrocartilage complex (TFCC) tears remains difficult. The purpose of this study was to evaluate whether dynamic computed tomography (CT) of the distal radioulnar joint (DRUJ) has a higher sensitivity in detecting foveal tears of the TFCC when compared with magnetic resonance imaging (MRI). A database query identified all patients above the age of 18 years with suspected foveal TFCC injuries who underwent bilateral dynamic CT imaging of the DRUJ, static 3T MRI, and subsequent wrist arthroscopy. All patients had evidence of foveal tenderness on clinical examination. The imaging results were validated with wrist arthroscopy. Twelve patients with a mean age of 31 years (range, 18-53 years) were identified. Eight patients were diagnosed with a complete foveal detachment of the TFCC on wrist arthroscopy. Of the 8 patients with a foveal tear on DRUJ arthroscopy, only 3 had a preoperative physical examination suggestive of DRUJ instability. Magnetic resonance imaging identified foveal injuries in 4 of these 8 patients (sensitivity, 50%), and 3 of these were identified as only partial tears. Dynamic CT identified instability of DRUJ in 6 of 8 patients (sensitivity, 75%). Seven of 8 patients had imaging findings suggestive of a foveal tear when including either MRI or CT imaging (sensitivity, 88%). Of the 4 patients with an intact foveal attachment on arthroscopy, 3 (specificity, 75%) had a stable DRUJ on CT and all 4 (specificity, 100%) had an intact foveal attachment on MRI. Sixty-two percent of patients with foveal tears on arthroscopy have a stable DRUJ on clinical examination. When combining MRI and dynamic CT imaging of the DRUJ, the sensitivity of detecting a foveal TFCC tear approaches 88% compared with a gold standard of wrist arthroscopy.

Comparing the Outcomes of Suture Anchor Repair and Rein-Type Capsular Suture for Triangular Fibrocartilage Complex Foveal Tears With a Minimum 2-Year Follow-Up

Recent biomechanical studies have highlighted the importance of foveal reinsertion when repairing triangular fibrocartilage complex (TFCC) injury with foveal tears. However, clinical studies comparing different repair techniques are scarce. We compared the clinical outcomes of suture anchor repair and rein-type capsular suture in patients with TFCC palmer 1B foveal tears with a minimum of 2-year follow-up. This was a single-surgeon, single-center, retrospective, comparative study. We included patients who underwent TFCC repair surgery due to a foveal tear from December 2013 to October 2018 with a minimum follow-up of 24 months. Postoperative Quick Disabilities of Arm, Shoulder, and Hand (QuickDASH) score, Modified Mayo Wrist Score, visual analogue scale for pain, wrist range of motion, and grip strength were compared. We also measured the maximal ulnar head displacement with dynamic ultrasound to quantify distal radioulnar joint stability. In total, 103 patients were in the suture anchor group (group A) and 84 patients in the rein-type capsular suture group (group B). The mean follow-up time exceeded three years for both groups. There was a minimal difference regarding QuickDASH score, visual analogue scale for pain, and grip strength ratio between the two groups. The rein-type group had significantly better Modified Mayo Wrist Score. The suture anchor group showed better distal radioulnar joint stability with dynamic ultrasound, but was more limited in ulnar deviation. However, these differences are most likely clinically insignificant. Both suture anchor repair and rein-type capsular suture yielded satisfactory results for TFCC 1B foveal tear in a minimum of 2-year follow-up. The functional scores were similar, and no major complications or recurrent instability were noted in either group. Retrospective therapeutic comparative investigation IV.

Primary Arthroscopy-Assisted Foveal Repair of Triangular Fibrocartilage Complex Associated with Acute Distal Radius Fractures in Young Adults

Abstract Background In distal radius fractures (DRFs) occurring in nonosteoporotic age groups, it is known that triangular fibrocartilage complex (TFCC) injuries are frequently combined, with some experiencing persistent symptomatic instability. However, a gold standard treatment for these associated lesions has not yet been established. Purpose Our purpose was to investigate the outcomes of primary arthroscopy-assisted transosseous foveal repair of the TFCC associated with DRFs in young adults. Methods Fifteen patients aged <65 years who underwent open reduction and internal fixation for DRF and arthroscopy-assisted repair for foveal tear of the TFCC were included. Those patients were observed to have complete peripheral TFCC tear on preoperative wrist magnetic resonance imaging and intraoperative distal radioulnar joint (DRUJ) stability tests. This was confirmed with an arthroscopic examination. The transosseous technique was used to repair the TFCC after firm fixation of the DRF. The patients were immobilized with the long-arm splint in a neutral position for 2 weeks postoperatively and a removable short-arm splint was applied for another 2 weeks. DRUJ stability, grip strength, and patient-reported outcomes, including disabilities of the arm, shoulder, and hand (DASH) and Patient-Rated Wrist Evaluation scores, were evaluated as primary outcomes at 3, 6, and 12 months postoperatively. Results All patients showed a stable DRUJ throughout the follow-up period. The average grip strength ratio compared to the unaffected side was 69, 83, and 90% at 3, 6, and 12 months after surgery, respectively. The mean DASH score was 26.9, 18.4, and 6.7 at 3, 6, and 12 months postoperatively, respectively. Conclusion Primary arthroscopy-assisted transosseous foveal repair of the TFCC with internal fixation of the distal radius resulted in early recovery and good clinical outcomes in young patients. Level of evidence Therapeutic, level IV.

Suture-Based Distal Radioulnar Joint Stabilization: A Biomechanical Evaluation in a Cadaveric Model

Abstract Purpose Management of acute distal radioulnar joint (DRUJ) instability is complex and controversial. Common treatment options include prolonged immobilization, stabilization with wires, and acute triangular fibrocartilage complex repair. However, none of these permits an early range of motion. The purpose of this study is to investigate the feasibility of a suture-based stabilization (SBS) technique for acute DRUJ instability to permit early active motion. Methods A biomechanical study utilizing eight cadaveric arms was performed. All specimens were tested in the intact state prior to the creation of bidirectional DRUJ instability. For the SBS group, 2-mm suture tapes with suture button fixation were utilized to recreate the respective contributions of distal oblique bundle and volar and dorsal radioulnar ligaments to DRUJ stability. All specimens were cyclically loaded with a simulated ballottement stress of 20N in forearm positions of neutral, 60 degrees of pronation and 60 degrees of supination. Range of motion and total translation were measured and then compared between the two groups. Results The average range of motion in the intact and SBS specimens was 174 and 175 degrees, respectively. There were no significant differences in displacement between the intact and SBS group in neutral and in supination. However, the SBS group had less translation than the intact group in pronation. Conclusions For acute DRUJ instability, the described SBS technique provides similar stability to the native intact DRUJ without compromising the range of motion in a cadaveric model. Future comparative studies are warranted prior to translation into the clinical arena. Clinical Relevance This is a biomechanical study investigating a treatment technique for acute DRUJ instability that would allow an early range of motion.

The Distal Oblique Bundle in the Distal Forearm: From Anatomical Features to Clinical Implementation.

Background and objective The distal oblique bundle (DOB) is nowadays recognized as thethickest component of the distal interosseous membrane (DIOM). It is neither thought to be a clear-cut ligament, and nor does it follow the typical configuration of the rest of the DIOM. It is not always present and some studies have raised disputes about its prevalence and a few anatomical features. In this study, we aimed to provide data on the prevalence and anatomical features of the DOB, which are of great importance at this early stage of research into the topic. Our findings have been correlated with current knowledge and are expected to contribute to clinical implementation. Materials and methods Twenty-eightfresh-frozen forearms were utilized for measurements. Specifically, mean length, width, distance from the middle of the bundle's insertion to the ulna to the tip of the styloid process of the ulna, as well as the distance from the midpoint of its insertion to the radius to the tip of the radiuses' styloid process were calculated. The prevalence was described with a cutoff thickness point of 0.5 mm. Early results based on three cases of DOB reconstruction with the "Riggenbach" technique due to distal radioulnar joint (DRUJ) instability were documented. Results Eleven DOBs were reported out of the 28 specimens, suggesting a prevalence of 39.3%. The mean thickness was 0.88 mm (range: 0.6-1.3 mm), the mean width was 5.22 mm (range: 2.2-8.4 mm), and the mean length was 25.68 mm (range: 22.7-29.2 mm). Proximally, the mean distance from the bundle's ulnar insertion to the tip of the styloid process of the ulna was 51.02 mm (range: 45.5-55.6 mm) while distally, the mean distance from the bundle's insertion to the radius to the tip of the styloid process of the radius was 34.5 mm (range: 31.3-37.7 mm). After a follow-up of at least six months, improvement was evident in all measured areas in the three patients who underwent surgery. Additionally, they reported satisfaction and accomplishment of their preoperative goals. Conclusions Discrepancies in measurements in some anatomic features between studies are probably due to variations in specimen types, measurement methods, and sites. Efforts must continue to be made on a more extensive scale and in a more standardized manner for more factual results and conclusions. "Reconstruction-recreation" or "original construction-creation" procedures yield promising results in a fast, simple, and less invasive manner than traditional methods of DRUJ stabilization.

Distal oblique bundle influence on distal radioulnar joint stability: a biomechanical study

Chronic instability of the distal radioulnar joint (DRUJ) presents a highly disabling condition. Several surgical techniques have been reported for its treatment. These involve reconstruction of the distal oblique bundle (DOB) of the interosseous membrane (IOM) of the forearm. The aim of this study was to examine whether surgical reconstruction of the DOB is necessary to restore DRUJ stability following trauma with DOB disruption and to compare two restoration techniques utilizing a tendon or suture-button graft. Stability in supination and pronation was assessed by means of maximum torque and force in twenty forearms. Test cycles were performed with the DOB/IOM in an intact condition, with the DOB or distal IOM transected, and following surgical reconstruction of the DOB with either tendon graft or suture-button system. In pronation, the relative change in maximum axial force was significantly lower in samples with a transected DOB in comparison to samples without a preexisting DOB. No statistically significant differences were observed between forearms including DOB reconstruction and specimens in the intact and transected state. Neither were there statistically significant differences concerning the two surgical techniques. From a biomechanical perspective, surgical DOB reconstruction is hence not indicated in cases of isolated DOB rupture.

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

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

Arthrex Mini Tightrope Fixation for Chronic Distal Radioulnar Joint Instability.

Chronic distal radioulnar joint (DRUJ) instability is a complex clinical condition that is difficult to treat. Currently, there is no gold standard treatment. We present a novel technique using Arthrex Mini Tightrope for DRUJ stabilization. In this case series, a 1.6 mm K-wire was passed transversely through the distal ulna and radius. The Mini Tightrope was inserted into the end of the K-wire and pulled through the bone tunnels. Appropriate tension was achieved to stabilize the joint according to individual laxity comparable to the contralateral side. Five patients (3 males and 2 females) comprised this pilot series, with a mean age of 27.1 years. All sustained a traumatic injury at an average of 12.4 months before surgery (range: 5 to 32 mo). In addition, 3 patients had central triangular fibrocartilage complex tears treated with arthroscopy at the time of Mini Tightrope placement. While one patient was lost to follow-up after 7 weeks postoperative due to incarceration, 4 patients demonstrated coronal and sagittal stability in the context of DRUJ motion and a satisfactory range of motion. The mean time for the return to work for the two patients who were laborers or normal activity postoperatively was 5.2 weeks (range: 1 to 16.4 wk). Unrestricted activity was generally allowed 8 weeks postoperatively but varied by patient. The same 4 patients underwent hardware removal at an average of 31 weeks (range: 15 to 44 wk). Although this is only a pilot series, this suggests that temporary Mini Tightrope stabilization of the DRUJ may be a viable solution while upholding the benefits of minimally invasive surgery.

Foveal triangular fibrocartilage complex pathology: a potentially under-recognized injury.

The primary aim of the present study was to present a case series of 24 patients with foveal triangular fibrocartilage complex (TFCC) injuries that were treated with arthroscopically assisted TFCC foveal repair. In total, 19 patients had a stable distal radioulnar joint (DRUJ) and five had an unstable DRUJ. Despite this, all patients were found to have a foveal tear upon DRUJ arthroscopy. Magnetic resonance imaging (MRI) scans detected only eight out of 23 patients with foveal injuries. In addition to their foveal injury, 19 of the 24 patients had additional pathology that required treatment. At a mean follow-up of 18 months, there was a statistically significant improvement in pain, range of motion, grip strength and functional scores. In this study, we demonstrate that having a stable DRUJ upon clinical examination and normal MRI findings does not rule out foveal TFCC injury and a high index of clinical suspicion is needed when managing patients with ulnar sided wrist pain.Level of evidence: IV.

Comparative Analysis of Treatment Outcomes: Modified Ulnar Gutter Slab vs. Sugar Tong Slab for Distal Radioulnar Joint Instability Following Triangular Fibrocartilage Complex Repair.

The standard treatment for distal radioulnar joint (DRUJ) instability involves repairing the triangular fibrocartilage complex (TFCC) and immobilizing the joint with a sugar tong slab, but this can cause elbow stiffness. To address this, a modified ulnar gutter slab was designed to enhance elbow mobility during immobilization. A prospective randomized controlled trial was conducted on 23 DRUJ instability patients who underwent arthroscopic TFCC repair. Two post-operative splinting techniques were compared: the modified ulnar gutter slab and the sugar tong slab. The assessment included the Disabilities of Arm, Shoulder, and Hand (DASH) score; elbow, forearm, and wrist range of motion (ROM); post-operative DRUJ stability; and complications. DASH scores at 4 and 6 weeks were not significantly different. However, the modified ulnar gutter slab improved elbow extension range of motion at 4 weeks (extension lag: 20.0 vs. 6.5 in the sugar tong group) (p = 0.011). Post-operative DRUJ stability was comparable between the two groups. Notably, one patient in the sugar tong slab group experienced complex regional pain syndrome (CRPS). The modified ulnar gutter slab offers a post-operative alternative after TFCC repair. It effectively immobilizes forearm and wrist motion while enhancing elbow mobility, potentially reducing post-operative elbow stiffness.

Mini-invasive Indirect Distraction in the Treatment of Neglected DRUJ Dislocations—A Novel Surgical Technique

Abstract Introduction: This study presents mini-invasive indirect distraction in the treatment of neglected distal radioulnar joint (DRUJ) dislocations as a novel surgical technique. Pure DRUJ dislocation is a rare injury caused by over rotation of the forearm. It is often undiagnosed in an acute setting. There is no consensus on the treatment of neglected dislocations. Materials and methods: We present a group of six patients with neglected pure DRUJ dislocation, treated by a single surgeon between 2012 and 2019. Results: Closed reduction was impossible in six of six patients. The indirect distraction allowed the reduction of the DRUJ in all cases with final stable DRUJ. Forearm rotation returned to normal in four patients, one patient had 50%, and another patient had 60% of the range of forearm. Mean pain dropped from 7 to 0.8 on visual analog scale. At the 2-year follow-up, the mean Disabilities of the Arm, Shoulder, and Hand score was 8 (0–37.5), and minor degenerative X-ray changes were observed in four patients. Level of evidence IV

Two-week versus four-week immobilization of stable distal radioulnar joint following surgical fixation of Galeazzi fracture-dislocations: A randomized controlled trial

BackgroundPostoperative immobilization protocols following surgical fixation of Galeazzi fracture-dislocations (GFD) in adults remain unresolved. This study aimed to compare outcomes of two different immobilization durations (two weeks versus four weeks) in terms of functional outcomes and complications. MethodsParticipants were prospectively and randomly enrolled in two-week versus four-week immobilization after plate fixation of GFD when the distal radioulnar joint (DRUJ) was reducible and stable postoperatively. Immobilization involved an above-elbow splint with the forearm in full supination. Demographic data, including age, gender, mechanism of injury, fracture characteristics, and treatment approach, were recorded. The primary outcome was the abbreviated version of the Disability of Arm, Shoulder, and Hand (DASH) scores at three months post-operation. Secondary outcomes included wrist range of motion, mean grip strength differences between injured and uninjured sides, and complications. ResultsA total of 54 participants were enrolled and randomized into two treatment groups. Demographics were similar between groups, with most participants being male, and the mean age was 35 years (range 18–65). Fractures were generally less than 10 cm. The mean DASH scores were slightly higher in the four-week immobilization group but not statistically significant (1.43 in the two-week immobilization group vs. 2.36 in the four-week immobilization group, p = 0.152). Range of motion and mean grip strength differences were similar between groups. Complication rates were also similar, with recurrent DRUJ dislocation occurring in two participants from each group. ConclusionThis study found no significant differences in functional outcomes and complications between two-week and four-week immobilization durations after plate fixation of GFD when the DRUJ was reducible and stable postoperatively. Level of evidenceTherapeutic Level I.

An alternative treatment for degenerative triangular fibrocartilage complex injuries with distal radioulnar joint instability: first experience with 48 patients.

Treatment of ulnar impaction syndrome combined with distal radioulnar joint instability due to irreparable degenerative triangular fibrocartilage complex injuries can be complex. We describe the outcomes of a novel technique for restoring distal radioulnar stability due to ulnar impaction syndrome using a distally based extensor carpi ulnaris tendon strip combined with ulnar shortening osteotomy in 48 patients. Patients were assessed using standardized outcome measurements. The patient-rated wrist/hand evaluation total score improved from 66 (SD 15) at intake to 40 (SD 25) at 3 months, and 28 (SD 23) at 12 months postoperatively (p < 0.001). Wrist extension and flexion improved significantly at 12 months from 53° (SD 11) to 65° (SD 8) (p < 0.001) and from 45° (SD 10) to 56° (SD 12) (p = 0.01), respectively. Adding a distally based longitudinal extensor carpi ulnaris strip to ulnar shortening osteotomy for restoring distal radioulnar joint stability seems to be an effective treatment in patients with irreparable degenerative triangular fibrocartilage complex injuries due to ulnar impaction syndrome. Level of evidence: IV.

A structured non-operative treatment program for traumatic triangular fibrocartilage complex tear: A quasi-experimental study

ObjectivesTriangular fibrocartilage complex (TFCC) injury is a common cause of ulnar-sided wrist pain. However, treatment protocols vary across clinical settings and a standardized treatment protocol is needed to improve quality of care.We devised a rehabilitation regime which comprised both orthoses and exercises. We hypothesized that the program can effectively reduce pain and improve functional performance. Materials and methodsThirty-two subjects participated in the 5-phase rehabilitation program. Progress was monitored every 3 weeks. Outcome measures comprised numeric pain rating scale (NPRS), activities of daily living (ADL) pain score, wrist range of motion (ROM), ADL performance score, patient-rated wrist evaluation (PRWE), power grip and distal radioulnar joint (DRUJ) instability grade. ResultsNPRS decreased from 5.3/10 to 0.5/10 while the ADL pain score improved from 10/20 to 19.1/20. ROM in flexion/extension and supination/pronation improved by 35%. Functional performance on ADL performance score and PRWE improved from 21/40 to 38/40 and 49.5/100 to 14.6/100, respectively. Power grip increased by 59.5%, and DRUJ stability improved. DiscussionThe combination of orthoses and progressive strengthening and proprioception training was effective in re-establishing DRUJ stability, and improving wrist strength and functional performance. ConclusionsThis study provided insight for the development of a rehabilitation protocol for patients with TFCC injury.

Does surgical reconstruction of the distal oblique bundle (DOB) provide similar stability as the intact bundle or Adams procedure? A systematic review

IntroductionThe aim of this review was to summarize the available evidence for biomechanical stability following surgical DOB reconstruction, and to determine whether distal radioulnar joint (DRUJ) stability with a reconstructed DOB was similar to the native intact condition or that after the Adams procedure. Material and methodsA systematic literature search according to the PRISMA guidelines was performed using the databases PubMed and Embase. The following search algorithm was used: (“DOB” OR “Distal Oblique Bundle”) AND “Reconstruction”. Biomechanical or human cadaveric studies that measured stability of the DRUJ after reconstruction of the DOB were included. ResultsFour articles were included in the final analysis. DOB incidence was reported to be between 50% and 70%. Two studies observed no differences between the intact situation and the reconstructed DOB, respectively the Adams procedure. A further author group found no signs of major instability after the Adams reconstruction or after DOB reconstruction, except for decreased stability during supination in the DOB sample. In another study, similar results could be shown for the Adams and DOB reconstruction groups; however, the DOB sample showed decreased dorsal translation of the radius during forearm supination. ConclusionIn conclusion, DOB reconstruction was proven to stabilize the DRUJ adequately. Moreover, the reconstructed DOB showed the same stability as the native DOB, except for one study, in which stability following reconstruction was reduced during supination. No significant difference between the DOB and the Adams reconstruction could be observed.

Stability of the distal radioulnar joint with and without activation of forearm muscles.

The purpose of this study was to quantify the effect of the flexor carpi ulnaris and the extensor carpi ulnaris muscles on distal radioulnar joint stability. The anteroposterior ulnar head translation in relation to the radius was measured sonographically when the forearm was in a neutral resting position and when the hand was actively pressed on to a surface, with and without intentional flexor carpi ulnaris and extensor carpi ulnaris activation, while also being monitored by an electromyogram. Data on 40 healthy participants indicated a mean anteroposterior translation in the distal radioulnar joint of 4.1 mm (SD 1.08) without and 1.2 mm (SD 0.54) with muscle activation. Our results indicate that intentional ulnar forearm muscle activation results in 70% less anteroposterior ulnar head translation and greater distal radioulnar joint stability. Therefore, the flexor carpi ulnaris and extensor carpi ulnaris muscles serve as dynamic stabilizers of the distal radioulnar joint. This finding may be clinically significant since ulnar forearm muscles strengthening may increase distal radioulnar joint stability.