Association between carpal height ratio and ulnar variance in normal wrist radiography.

INTRODUCTION: The wrist joint is a complex anatomical structure, and various radiographic parameters are utilized to assess its normal alignment and orientation. Among these parameters are carpal height ratio (CHR) and ulnar variance (UV). Previous literature has indicated that factors such as age and gender may influence these parameters; However, there is a lack of studies investigating these differences specifically in the Middle East or Jordan. Additionally, no prior research has explored the relationship between UV and CHR. Therefore, the objective of this study is to investigate these critical radiological parameters and their associations. METHODOLOGY: A cross-sectional study design was employed, wherein a total of 385 normal wrist X-rays were reviewed, and CHR and UV were measured. Intra-observer and inter-observer reliability assessments were conducted to ensure the consistency and accuracy of measurements. Additionally, the association between UV and CHR was measured and plotted for further analysis. RESULTS: In our study, the mean CHR was 0.5 (range: 0.4 to 1.5), and the mean UV was - 0.3 mm (range: -5.8 mm to 4.1 mm). We found a significant negative correlation between CHR and age (p < 0.05). No significant gender differences were observed in UV and CHR. Additionally, a weak positive correlation was found between UV and CHR (Pearson correlation coefficient = 0.13, p = 0.01; adjusted R2 = 0.014, p = 0.02). CONCLUSION: Age correlated significantly with a decline in carpal height ratio. Additionally, ulnar variance had a week positive yet significant correlation with carpal height ratio. LEVEL OF EVIDENCE: Cross-sectional study, Level III.

Effect of the Sauvé-Kapandji method on the wrist contact surface for distal radial ulnar joint disorders.

BACKGROUND: The Sauvé-Kapandji (S-K) method is a surgical procedure performed for chronic deformities of the distal radial ulnar joint (DRUJ). Changes to the joint contact surface from pre- to postoperatively under physiological in vivo conditions have not yet been determined for this useful treatment. The aim of the present study was therefore to compare the articular contact area of the wrist joint between before and after the S-K method for DRUJ disorders. METHODS: The SK method was performed for 15 patients with DRUJ osteoarthritis and ulnar impaction syndrome. We calculated the Mayo Wrist Score as the patient's clinical findings and created 3-dimensional bone models of cases in which the S-K method was performed and calculated the contact area and shift in the center of the contact area using customized software. RESULTS: The Mean modified Mayo Wrist Score improved significantly from 60.3 preoperatively to 80.3 postoperatively (P < 0.01). Scaphoid contact area to the radius increased significantly from 112.6 ± 37.0 mm2 preoperatively to 127.5 ± 27.8 mm2 postoperatively (P = 0.03). Lunate contact area to radius-ulna was 121.3 ± 43.3 mm2 preoperatively and 112.5 ± 37.6 mm2 postoperatively, but this decrease was not significant (P = 0.38). Contact area ratio of scaphoid to lunate increased significantly from 1.01 ± 0.4 preoperatively to 1.20 ± 0.3 postoperatively (P = 0.02). Postoperative translations of the center of the scaphoid and lunate contact areas were decomposed into ulnar and proximal directions. Ulnar and proximal translation distances of the scaphoid contact area were 0.8 ± 1.7 mm and 0.4 ± 0.6 mm, respectively, and those of the lunate contact area were 1.1 ± 1.7 mm and 0.4 ± 1.1 mm, respectively. This study revealed changes in wrist contact area and center of the contact area before and after the S-K method. CONCLUSION: These results may accurately indicate changes in wrist joint contact area from pre- to postoperatively using the S-K method for patients with DRUJ disorder. Evaluation of changes in contact area due to bone surface modeling of the wrist joint using 3DCT images may be useful in considering surgical methods.

Effect of muscle length in a handgrip task on corticomotor excitability of extrinsic and intrinsic hand muscles under resting and submaximal contraction conditions.

The neurophysiological mechanisms underlying muscle force control for different wrist postures still need to be better understood. To further elucidate these mechanisms, the present study aimed to investigate the effects of wrist posture on the corticospinal excitability by transcranial magnetic stimulation (TMS) of extrinsic (flexor [FCR] and extensor carpi radialis [ECR]) and intrinsic (flexor pollicis brevis (FPB)) muscles at rest and during a submaximal handgrip strength task. Fourteen subjects (24.06 ± 2.28 years) without neurological or motor disorders were included. We assessed how the wrist posture (neutral: 0°; flexed: +45°; extended: -45°) affects maximal handgrip strength (HGSmax ) and the motor evoked potentials (MEP) amplitudes during rest and active muscle contractions. HGSmax was higher at 0° (133%) than at -45° (93.6%; p < 0.001) and +45° (73.9%; p < 0.001). MEP amplitudes were higher for the FCR at +45° (83.6%) than at -45° (45.2%; p = 0.019) and at +45° (156%; p < 0.001) and 0° (146%; p = 0.014) than at -45° (106%) at rest and active condition, respectively. Regarding the ECR, the MEP amplitudes were higher at -45° (113%) than at +45° (60.8%; p < 0.001) and 0° (72.6%; p = 0.008), and at -45° (138%) than +45° (96.7%; p = 0.007) also at rest and active conditions, respectively. In contrast, the FPB did not reveal any difference among wrist postures and conditions. Although extrinsic and intrinsic hand muscles exhibit overlapping cortical representations and partially share the same innervation, they can be modulated differently depending on the biomechanical constraints.

Does Radiographic Alignment Correlate With Patient-Reported Functional Outcomes and Posttreatment Complications in Older Patients Treated for Wrist Fractures?

PURPOSE: Surgical treatment of distal radius fractures provides better fracture alignment than closed reduction; however, surgical treatment does not lead to better patient-reported function at 12 months. The aims of this study were to report the radiographic outcomes from the Combined Randomized and Observational Study of Surgery for Fractures In the distal Radius in the Elderly trial, investigate the association between radiographic outcomes and patient-reported function, and explore whether this association was affected by posttreatment complications and direction of malalignment. METHODS: This study used the outcomes of the Combined Randomized and Observational Study of Surgery for Fractures In the distal Radius in the Elderly trial, which is a combined randomized and observational trial that compared volar-locking plate fixation with closed reduction and cast immobilization, to treat distal radius fractures in patients aged ≥60 years. Four radiographic outcomes (dorsal angulation, radial inclination, ulnar variance, and articular step) were reported at the following three time frames: (1) baseline, (2) after treatment, and (3) ≥6 weeks by treatment group. Secondary analysis was correlation of 12-month patient-reported function scores with 6-week radiographic measures for each of four radiographic parameters, and a subgroup analysis was conducted to investigate if this was affected by posttreatment complications. Tertiary analysis investigated if direction of malalignment affected the secondary analysis. RESULTS: We recruited 300 participants (166 randomized and 134 observational); 113 had volar-locking plate fixation, and 187 had closed reduction. There were no between-group differences for each of the four pretreatment radiographic parameters, but there were between-treatment group differences for all four radiographic parameters apart from articular step. We found no association between patient-reported function at 12 months and each of the four radiographic parameters at 6 weeks. This lack of association was unaffected by posttreatment complications and the direction of malalignment. CONCLUSIONS: For patients with wrist fractures aged ≥60 years, final radiographic alignment did not correlate with patient-reported function at 12 months. These findings were not affected by treatment type, and there was no association between radiographic alignment and posttreatment complications. TYPE OF STUDY/LEVEL OF EVIDENCE: Therapeutic IV.

Dynamic palmar dislocation of the ulnar head at the distal radioulnar joint (DRUJ) after radius shaft malunion.

INTRODUCTION: Palmar instability of the distal radioulnar joint (DRUJ) is a rare condition, which is, in contrast to the dorsal dislocation, scarcely represented in the literature. This palmar instability can result from a dorsally angulated malunion of the radial shaft after forearm fracture in childhood. Treating such a condition is controversial in the literature and was described in small case series. This study represents the largest case series in the literature that dealt with this condition, alongside a review of the key papers in the English literature. MATERIALS AND METHODS: This is a retrospective case series. Ten patients were operated between 2007 and 2014. Six patients could be followed up clinically and radiologically after radius corrective osteotomy at the site of malunion with a mean time of 5.6 years. Patient history revealed a conservatively treated forearm fracture in childhood, a symptom-free period of several years [mean of 21.5 (min-max: 9.4-26.5) years] and a minor trauma as a trigger for clinical symptoms. All patients had clinically a DRUJ instability with palmar luxation of the ulnar head at supination. A diagnostic key feature is a radiograph of the whole forearm, revealing malunion of the radius at shaft level. Retrospective patient history, diagnostic imaging, operative technique and clinical results (DASH, modified Mayo Wrist Score, pain, grip strength, range of motion) were analyzed. RESULTS: Four patients were lost to follow-up. In all patients, a radius corrective osteotomy could stabilize the DRUJ. In one patient, the osteosynthesis was revised due to metal failure after one month. In all the six patients, bony union of the osteotomy was achieved. In another patient, an additional ulnar shortening osteotomy was done one year later due to a positive ulnar variance. Postoperative range of motion of the wrist had an average of 136° in extension/flexion and 149° in pronation/supination, and grip strength was 89% of the opposite side. With an average of 12.5 points at the DASH score and 82 at the modified Mayo Wrist Score, patients rated their hand function as good. CONCLUSIONS: In this patient cohort, a simple corrective osteotomy of the radial shaft at the malunion site was adequate to treat the dynamic palmar instability of DRUG. A soft tissue procedure was not required. Forearm radiographs are the mainstay of diagnostic tools.

Effect of Kinesio taping on wrist kinematics and functional performance: A randomized controlled trial.

BACKGROUND: Kinesio taping (KT) is a popular adjunct treatment modality for musculoskeletal injuries, hand and wrist injuries. The effectiveness of KT on wrist kinematics has been analyzed during single plane movements in general, and no study has investigated its effectiveness during dart throwing motion (DTM). PURPOSE: To compare the effects of different KT techniques on wrist kinematics during DTM and functional performance of hand in healthy participants. STUDY DESIGN: Randomized, double-blind, placebo-controlled, crossover study. METHODS: Seventy-two healthy participants were included. Dominant wrist kinematics during DTM was evaluated by a Leap motion controller and wrist functional performance was evaluated by Minnesota Manual Dexterity Test. In order to compare the effects of KT on different muscles and also the effects of KT and placebo taping (PT), wrists of participants were evaluated under 5 conditions: without any taping, KT on flexor carpi ulnaris (FCU), KT on extensor carpi radialis brevis and longus (ECRB/L), PT on FCU and PT on ECRB/L. Means of outcome measures without any taping and with different 4 tapings were compared by repeated measures analysis of variance. PT and KT effects were compared by Wilcoxon signed rank test. RESULTS: DTM range increased (P = .0) and Minnesota Manual Dexterity Test time decreased (P = .0) after KT and PT applications on FCU and ECRB/L muscles. Amount of change in wrist kinematics (P = .0; effect size = 0.2 and 0.3) and functional performance (P = .0; effect size = 0.6 and 0.8) were more obvious with KT applications, independent from the muscles they were applied on (P = .2 for wrist kinematics and P = .7 for functional performance). CONCLUSIONS: KT on either FCU or ECRB/L muscles improve wrist kinematics and functional performance, significantly. Further studies should investigate if these findings apply for the patients with different wrist injuries, for both immediate- and long-term effectiveness.

Comparison of AI-powered 3D automated ultrasound tomography with standard handheld ultrasound for the visualization of the hands-clinical proof of concept.

OBJECTIVE: To assess the ability of a newly developed AI-powered ultrasound 3D hand scanner to visualize joint structures in healthy hands and detect degenerative changes in cadaveric hands. MATERIALS AND METHODS: Twelve individuals (6 males, 6 females, age 43.5 ± 17.8 years) underwent four scans with the 3D ultrasound tomograph (right and left hand, dorsal and palmar, respectively) as well as four sets of handheld ultrasound of predefined anatomic regions. The 3D ultrasound tomographic images and the standard handheld ultrasound images were assessed by two radiologists with regard to visibility of bone contour, joint capsule and space, and tendons. In addition, three cadaveric hands were scanned with the 3D ultrasound tomograph and CT. RESULTS: Mean scan time for both hands was significantly faster with handheld ultrasound (10 min 30 s ± 95 s) compared to 3D ultrasound tomography (32 min 9 s ± 6 s; p < 0.001). Interreader and intermodality agreement was moderate (0.4 < κ ≤ 0.6) to substantial (0.6 < κ ≤ 0.8). Overall visibility of joint structures was comparable between the modalities at the level of the wrist (p = 0.408), and significantly better with handheld ultrasound at the level of the finger joints and the thumb (both p < 0.001). The 3D ultrasound tomograph was able to detect osteophytes in cadaveric hands which were confirmed by CT. CONCLUSION: The AI-powered 3D ultrasound tomograph was able to visualize joint structures in healthy hands and singular osteophytes in cadaveric hands. Further technical improvements are necessary to shorten scan times and improve automated scanning of the finger joints and the thumb.

Quantifying in vivo scaphoid, lunate, and capitate kinematics using four-dimensional computed tomography.

OBJECTIVE: We aimed to establish a quantitative description of motion patterns and establish test-retest reliability of the four-dimensional CT when quantifying in vivo kinematics of the scaphoid, lunate, and capitate. MATERIALS AND METHODS: We assessed in vivo kinematics of both wrists of 20 healthy volunteers (11 men and 9 women) between the ages of 20 and 40 years. All volunteers performed active flexion-extension and radial-ulnar deviation with both wrists. To test for reliability, one motion cycle was rescanned for both wrists approximately 15 min after the first scan. The coefficient of multiple correlation was used to analyze reliability. When two motion patterns are similar, the coefficient of multiple correlation tends towards 1, whereas in dissimilar motion patterns, it tends towards 0. The root mean square deviation was used to analyze the total motion patterns variability between the two scans. RESULTS: Overall, mean or median coefficient of multiple correlations were higher than 0.86. The root mean square deviations were low and ranged from 1.17° to 4.29°. CONCLUSION: This innovative non-invasive imaging technique can reliably describe in vivo carpal kinematics of uninjured wrists in healthy individuals. It provides us with a better understanding and reference values of carpal kinematics of the scaphoid, lunate, and capitate.

Outcomes Associated With Scapholunate Ligament Injury Following Intra-Articular Distal Radius Fractures.

PURPOSE: The purpose of this study was to evaluate a series of intra-articular distal radius fractures (DRFs) to determine whether patients without radiographic evidence of scapholunate (SL) ligament injury have a difference in outcomes in comparison with patients with radiographic evidence of SL ligament injury and no ligament repair or reconstruction. Our hypothesis is that there are no significant differences in outcomes between patients after treatment of their intra-articular DRF. METHODS: A retrospective analysis of patients from a single institution who sustained an intra-articular DRF from January 2006 through January 2019 with minimum 12-month (n = 192) and 24-month (n = 100) follow-up was performed. Patient demographic, clinical, and outcome variables were compared between SL angles less than 70° (cohort 1) and SL angles 70° or greater (cohort 2). Radiographic parameters were measured and recorded at 3 time points: baseline in the contralateral wrist, following closed reduction but prior to surgical intervention, and at final follow-up. Outcomes collected included Quick Disabilities of the Arm, Shoulder, and Hand (QuickDASH), Modified Global Assessment of Function (mGAF), and a visual analog scale (VAS) for pain. RESULTS: One hundred ninety-two patients were included. Of these 192 patients, cohort 1 (n = 110) was observed to have median (range) SL angles of 58° (42°-68°) and cohort 2 (n = 82) median (range) SL angles of 74.5° (70°-87°) after closed reduction. Cohort 2 had statistically significant increases in median SL angles from closed reduction to final follow-up (74.5° [range, 70°-87°) to 78.5° (range, 71°-107°). There were no statistically significant differences in QuickDASH disability scores, mGAF scores, and VAS pain scores between the cohorts at initial and final follow-ups. CONCLUSIONS: Patient-reported outcomes at 12 and 24 months do not differ between patients without radiographically apparent SL ligament injury (SL angles < 70°) and patients with radiographically apparent SL ligament injury(SL angles ≥ 70°) who do not undergo ligament repair or reconstruction following treatment of their intra-articular DRF. TYPE OF STUDY/LEVEL OF EVIDENCE: Therapeutic IV.

Exploring contrast-enhanced MRI findings of the clinically non-inflamed symptomatic pediatric wrist.

BACKGROUND: Knowledge of the synovial and tenosynovial appearance of the clinically non-arthritic symptomatic juvenile wrist using contrast-enhanced magnetic resonance imaging (MRI) is sparse. OBJECTIVES: To analyze contrast-enhanced MRI findings of the clinically non-inflamed symptomatic pediatric wrist, focusing on the enhancing synovial and tenosynovial membrane. To evaluate the coexistent presence of (teno)synovial enhancement, joint fluid, bony depressions and medullary changes suggestive of bone marrow edema. MATERIALS AND METHODS: We included 20 children (15 girls; age range: 7.5-17.6 years) who underwent contrast-enhanced MRI of the wrist, based on initial clinical indication, and eventually turned out to be unaffected by arthritic or orthopedic disorders. Various imaging characteristics of the synovium, tenosynovium, joint fluid, bone tissue and bone marrow were evaluated using existing MRI scoring systems. RESULTS: In 3/20 (15%) children, mild or moderate-severe synovial enhancement was observed and 2/20 (10%) children showed mild tenosynovial enhancement/thickening. Joint fluid (11/20 children; 55%), bony depressions (20/20 children; 100%) and medullary changes suggestive of bone marrow edema (6/20; 30%) were found in a substantial percentage of children. The most frequently observed combination of coexisting imaging characteristics was bony depressions with ≥2 mm joint fluid, which was found in 7/20 (35%) children. Simultaneous presence of synovial and tenosynovial enhancement/thickening, bony depressions and medullary changes suggestive of bone marrow edema was observed in one child. CONCLUSION: Several juvenile idiopathic arthritis-relevant MRI characteristics can be observed in the clinically non-inflamed symptomatic pediatric wrist.

A Pilot Study to Assess the Reliability of Sensing Joint Acoustic Emissions of the Wrist.

Joint acoustic emission (JAE) sensing has recently proven to be a viable technique for non-invasive quantification indicating knee joint health. In this work, we adapt the acoustic emission sensing method to measure the JAEs of the wrist-another joint commonly affected by injury and degenerative disease. JAEs of seven healthy volunteers were recorded during wrist flexion-extension and rotation with sensitive uniaxial accelerometers placed at eight locations around the wrist. The acoustic data were bandpass filtered (150 Hz-20 kHz). The signal-to-noise ratio (SNR) was used to quantify the strength of the JAE signals in each recording. Then, nine audio features were extracted, and the intraclass correlation coefficient (ICC) (model 3,k), coefficients of variability (CVs), and Jensen-Shannon (JS) divergence were calculated to evaluate the interrater repeatability of the signals. We found that SNR ranged from 4.1 to 9.8 dB, intrasession and intersession ICC values ranged from 0.629 to 0.886, CVs ranged from 0.099 to 0.241, and JS divergence ranged from 0.18 to 0.20, demonstrating high JAE repeatability and signal strength at three locations. The volunteer sample size is not large enough to represent JAE analysis of a larger population, but this work will lay a foundation for future work in using wrist JAEs to aid in diagnosis and treatment tracking of musculoskeletal pathologies and injury in wearable systems.

[Post-traumatic growth impairment following pediatric distal radius fractures resulting in an ulnar variance : A case report]. / Posttraumatische Wachstumsstörung nach kindlichen distalen Radiusfrakturen mit Entwicklung einer Ulnalängenvarianz : Ein Fallbeispiel.

BACKGROUND: Fractures of the distal forearm are common in children. While we treat adults by trying to anatomically reconstruct the wrist joint, in children, fracture treatment is predominantly conservative due to the high correction potential of the distal growth plate. However, the presentation of young adults with post-traumatic wrist pain is not unusual. OBJECTIVES: Do pediatric distal forearm fractures really heal without consequences despite a large tolerance of axial deviation? MATERIALS AND METHODS: Review of the literature, discussion of results and case report. RESULTS: Positive ulnar variance is the most common sequelae of pediatric distal forearm fractures. A positive variance of as little as >2 mm frequently causes ulnar-sided wrist pain and loss of motion, as is also shown in our case. CONCLUSIONS: Careful follow-up is advisable beyond fracture union following pediatric distal forearm fractures, especially after transphyseal osteosynthesis or growth plate involvement. Reconstructively corrective osteotomy of the ulna should be considered in patients with corresponding clinical symptoms, radiological findings and a positive ulnar variance of >2 mm.

Overuse wrist injuries in young athletes: What do sports physicians consider important signals and functional limitations?

This study's objective was to collect items from experienced sports physicians, relating to the presence and severity of overuse wrist injuries in young athletes, for developing a measurement instrument for signals of overuse wrist injury. Seven Dutch elite sports physicians involved in guidance and treatment of young athletes in wrist-loading sports (gymnastics, tennis, judo, field hockey, volleyball and rowing) participated in a focus group. They discussed signals and limitations related to overuse wrist injuries in young athletes. Data were coded and categorised into signals and limitations with subcategories, using an inductive approach. Of the resulting 61 signals and limitations in nineteen (sub)categories, 20 were considered important, forming a comprehensive item set for identifying overuse wrist injury in young athletes. Signals such as pain, "click", crepitations, swelling and limited range of motion were marked useful for early identification of overuse wrist injury. Limitations in movement and performance were considered indicative of severe overuse injury but less relevant for initial injury identification. The focus group provided 17 important signals and 3 important limitations indicative of overuse wrist injury. These provide the basis for a valid measurement instrument for identifying overuse wrist injury in young athletes, with equal emphasis on pain and on other symptoms.

Effect of Push-Up Position on Wrist Joint Pressures in the Intact Wrist and Following Scapholunate Interosseous Ligament Sectioning.

PURPOSE: To determine the contact pressures between the scaphoid and lunate and the distal radius during 2 wrist push-up positions before and following scapholunate interosseous ligament (SLIL) sectioning. METHODS: Eight fresh cadaveric wrists were tested in a neutral flexion-extension (knuckle) push-up position and in an extended push-up position. Pressure measurements were acquired as each wrist was loaded with the wrist in extension and with the wrist in a neutral position. Data were acquired with the SLIL intact and following sectioning of its dorsal, volar, and proximal components. The wrist was disarticulated and a map drawn on each sensor to identify each joint fossa. RESULTS: A push-up performed with the wrist in extension caused a significantly greater peak pressure in the radioscaphoid fossa but not in the radiolunate fossa. Moving the wrist into extension caused a significant dorsal movement of the pressure centroid an average of 2.9 mm in the radiolunate fossa and an average of 5.7 mm in the radioscaphoid fossa. Sectioning the SLIL caused the centroid of pressure in the radioscaphoid fossa to significantly move an average 1.4 mm radially. CONCLUSIONS: A push-up with the wrist in extension causes a significant increase in the pressure in the radioscaphoid fossa but not in the radiolunate. This finding may help explain why degenerative arthritis first develops in the radioscaphoid fossa before involving the radiolunate fossa. As expected, gapping that occurs with SLIL injury was observed here as a radial translation of the scaphoid and not as a movement of the lunate. The new location of scaphoid contact may be an additional reason for the development of radioscaphoid arthritis occurring before radiolunate arthritis. CLINICAL RELEVANCE: This study provides a possible explanation as to why degenerative arthritis may first occur in the radioscaphoid fossa.

[Treatment of the ulnar impingement syndrome in the distal radioulnar joint]. / Die Therapie des Impingementsyndroms im distalen Radioulnargelenk.

Ligamentous stability and joint congruity are prerequisites for a physiological function of the distal radioulnar joint (DRUJ). Impingement of the ulnar head may be caused by a congenital ulna-minus variance or by an iatrogenically excessive ulna shortening osteotomy. This impingement is detected by a positive compression test at the DRUJ. Radius correction osteotomy with shortening and correction of the radial inclination to restore the sigmoid notch may solve the problem by reducing the pressure between both joint partners and by promoting the remodelling of the DRUJ. This technique may restore the distal radioulnar joint and thus prevent the necessity of salvage procedures.

[The proximal radioulnar joint in consideration of the distal radioulnar joint]. / Das proximale Radioulnargelenk unter Berücksichtigung des distalen Radioulnargelenks.

The movement of the forearm follows a complex interplay of three main components: the proximal and distal radioulnar joint and the interosseous membrane. Injuries to one or even all components have a huge impact on the integrity of this system. The Essex-Lopresti lesion presented a high challenge in clinical diagnostics as well as therapy. Reconstructions of the length and stability are essential for a satisfactory postoperative outcome. If a reconstruction of the radial head by osteosynthesis is not possible, a radial head prosthesis should be implanted in the case of longitudinal instability - avoiding overlapping and/or oversizing. The reconstruction of the interosseous membrane should be considered, as well as the assessment of the distal radioulnar joint and/or the triangular fibrocartilage complex. Various reconstruction options are available in this regard.

[Radiology of the distal radioulnar joint and the ulnocarpal complex]. / Radiologie des distalen Radioulnargelenks und des ulnokarpalen Komplexes.

X-ray images exposed in neutral position and radiocarpally centred are essential in imaging of the distal radioulnar joint (DRUJ). The anatomic orientation of the DRUJ is favourable for acquiring transaxial scans to display its anatomy, subtle derangements, osteoarthritis and intra-articular fractures free from superpositions. The triangular fibrocartilage complex (TFCC) is the most important stabilizer of the DRUJ. Provided that a focused clinical indication is given, high-resolution images are acquired, and an intra-venous or intra-articular contrast-agent is applied, all TFCC structures and destabilizing lesions can be displayed with the use of CT and MRI.

[Anatomy and biomechanics of the distal radioulnar joint]. / Anatomie und Biomechanik des distalen Radioulnargelenks.

BACKGROUND: The functionality of the upper extremity is decisively based on rotation of the forearm. The rotation depends on the extent of motion of the distal radioulnar joint. Rotation enables complete and focused usability of the hand in order to cope with daily activities. The configuration of the distal radioulnar joint has developed over millions of years of evolution. ANATOMIC CONDITIONS: The triangular fibrocartilage complex is the crucial stabiliser of the latter joint since osseous structures are limited. The palmar and dorsal radioulnar ligaments belong to this complex. The superficial and deep parts of the latter ligaments insert both centrically in accordance to the axis of rotation and eccentrically. This arrangement guarantees stability of the joint throughout pronosupination. The interosseous membrane is a further relevant stabiliser that guarantees sufficient load transmission from radius to ulna. The distal oblique bundle of the interosseous membrane is outstanding in this context. The pronator quadratus muscle is the relevant dynamic stabiliser of the distal radioulnar joint. Contraction of the muscle prevents diastasis of the joint. The deep head of the muscle is always activated during pronosupination.

[Clinical examination of the distal radioulnar joint]. / Klinische Untersuchung des distalen Radioulnargelenks.

BACKGROUND: The distal radioulnar joint (DRUJ) provides the distal link between radius and ulnar and is the centre of rotation during pronation and supination. Pronation and supination are essential in controlling the posture and optimal presentation of the hand to grasp an object. In addition, pronation and supination enable us to rotate tools when they are in the longitudinal axis of the forearm. Due to this, the DRUJ plays a central role in the performance of activities in daily life. DIAGNOSTICS: Examination of the ulnar-side of the wrist remains challenging for hand surgeons due to a wide range of pathologies with overlapping clinical symptoms. Therefore, the clinical examination must be carried out carefully to detect the origin of the patient's complaints. Several special examination techniques are available, but their application and interpretation strongly depend on the skills and experience of the physician. Most tests are not evaluated in comparison to the gold standard of wrist arthroscopy with respect to sensitivity and specificity. The most reliable test for the DRUJ are the ulnar fovea sign, the dorsopalmar stress test and the press test.