Osseous Anatomy of the Distal Radioulnar Joint: An Assessment Using 3-Dimensional Modeling and Clinical Implications

Radiographic measurements in distal radius fracture evaluation: a review of current techniques and a recommendation for standardization

Radiographic measurements play a crucial role in evaluating the alignment of distal radius fractures (DRFs). Various manual methods have been used to perform the measurements, but they are susceptible to inaccuracies. Recently, computer-aided methods have become available. This review explores the methods commonly used to assess DRFs. The review introduces the different measurement techniques, discusses the sources of measurement errors and measurement reliability, and provides a recommendation for their use. Radiographic measurements used in the evaluation of DRFs are not reliable. Standardizing the measurement techniques is crucial to address this and automated image analysis could help improve accuracy and reliability.

Corrective osteotomy of the distal radius with palmar locking plate osteosynthesis without bone grafting and without cortical contact

The aim of this study was to assess bone healing and secondary fracture displacement after corrective osteotomy of the distal radius without any cortical contact using palmar locking plates without bone grafting. Between 2009 and 2021, 11 palmar corrective osteotomies of extra-articular malunited distal radius fractures and palmar plate fixations without the use of bone grafts and without cortical contact, were assessed. All patients showed complete osseous restoration and significant improvement in all radiographic parameters. Except for one patient, there were no secondary dislocations or loss of reduction in the postoperative follow-up. Bone grafts may not be mandatory for bone healing and prevention of secondary fracture displacement after palmar corrective osteotomy without cortical contact and fixation with palmar locking plate.Level of evidence: IV.

Reliability and Validity Analysis of the Distal Radioulnar Joint Ballottement Test

PURPOSE

Triangular fibrocartilage complex injuries can cause distal radioulnar joint (DRUJ) instability, which can be evaluated clinically with the DRUJ ballottement test. However, the reliability and validity of the test are unclear. This study aimed to analyze the reliability and validity of the test using a tracking device on healthy participants and patients with triangular fibrocartilage complex injuries.

METHODS

In this cross-sectional study, three orthopedic hand surgeons performed the DRUJ ballottement test using a technique of holding the carpal bones to the radius on 25 healthy participants (50 hands; 10 men and 15 women; mean age, 33 years; range, 20-51 years) and eight patients with triangular fibrocartilage complex injuries (16 hands; six men and two women; mean age, 43 years; range, 27-59 years). We used a three-dimensional electromagnetic tracking device to quantify the movement of the DRUJ and verify the reliability and validity of the test.

RESULTS

The intrarater and interrater intraclass correlation coefficients for DRUJ movement were 0.77 and 0.61, respectively, and the kappa coefficient for grading of DRUJ instability was 0.79. The correlation coefficient between DRUJ movement measured using the tracking device and instability judged clinically was 0.77. A comparison of healthy participants and the patients showed significantly greater DRUJ movement in the patients.

CONCLUSIONS

The test showed substantial intrarater and interrater reliability for assessing DRUJ movement and instability. The significant positive correlation between DRUJ movement and instability indicates the concurrent validity of the test. Moreover, the test showed discriminative validity in identifying mild or moderate DRUJ instability.

CLINICAL RELEVANCE

The DRUJ ballottement test using the holding technique has a relatively high diagnostic accuracy and can be used to assess DRUJ instability.

Morphometry of sigmoid notch: A novel method of shape assessment for clinical practice

Purpose

Using a novel technique, we assess and describe the distal radioulnar joint (DRUJ) anatomy with reference to sigmoid notch shapes. The purpose of this study was to develop a non-invasive, fast, reliable and reproducible technique for analysing the shapes of sigmoid notch on CT scans.

Methods

40 cadaveric wrist specimens exposing the sigmoid notch and 100 normal adult wrist CT scans with end on axial sections showing the sigmoid notch outline were obtained. The shape of the sigmoid notch was assessed on both using the geometric construction method.

Results

Of the 40 cadaveric specimens, 42 % were C-shaped, 33 % were flat,17 % were Ski sloped, and 8 % were S-shaped.Of the 100 wrist CT scans, 48 % were C-shaped sigmoid notch, 17 % were flat, 15 % were ski-sloped, and 20 % were S-shaped shapes.

Conclusions

Our sample population had a higher prevalence of C-shaped sigmoids in both cadaveric and CT-based studies. It is considered the most stable shape because of its increased depth. The DRUJ morphology in our sample population can be inferred to have a stable configuration.

Clinical relevance

The relationships and measurements demonstrated in this study can be a guide when considering ligament reconstruction for DRUJ instability, managing complex fractures involving the DRUJ and in decision-making for notchplasty, osteotomy and arthroplasty of DRUJ.

Reliability of the Sigmoid Notch Classification of the Distal Radioulnar Joint

Background  The Tolat sigmoid notch classification is a commonly used classification to characterize the distal radioulnar joint (DRUJ). This classification was based on a limited assessment of the entire joint, which may lead to inaccuracies in sigmoid notch evaluation. Questions/Purposes  The purpose of this study is to assess the reliability of the Tolat classification for sigmoid notch characterization. Methods  The sigmoid notch of 52 models of cadaveric forearms was assessed by applying the Tolat classification to the three-dimensional (3D) modeled notch and then slices at the start of the notch (0 mm) and 4 mm more proximal. The inter- and intrarater agreement was assessed using Cohen's and Fleiss' kappa statistic. Results  Agreement between iterations regardless of slices or surgeons/radiologists was moderate. Intrarater agreement between pairs of slices (0 vs 4 mm, 0 mm vs 3D, 4 mm vs 3D) was moderate, whereas agreement between all slices was slight. Agreement between surgeons and between radiologists was moderate, while agreement across all raters and slices was fair. Models described as "other" were more consistent in 3D classifications and were commonly classified as a reverse ski slope. Conclusions  Classification using the Tolat scheme is fair to moderate at best. Classification of the sigmoid notch using an axial view of the distal radius may not accurately reflect the anatomy throughout the notch. Clinical Relevance  The Tolat classification supplies a limited analysis of the sigmoid notch, and does not represent a comprehensive evaluation of the entire joint. Future classification systems should characterize the entire sigmoid notch.

Radiographic Determination of the Distal Ulnar Diaphyseal Angle

PURPOSE

Characterizing the distal ulnar diaphyseal angle (DUDA) may be important for anatomic recreation of the distal ulna during ulnar shortening osteotomy procedures using conventional straight plates. This study characterized the DUDA and determined side-to-side, age, and sex effects on DUDA magnitudes and locations.

METHODS

Retrospective analyses of bilateral wrist radiographs were performed on 60 patients. The DUDA was defined as the angle of intersection between a line passing through the center of the distal ulnar metadiaphyseal region, in line with the landmarked long axis of the ulna, on a lateral radiograph. This inflection point was measured from the most distal aspect of the ulnar head and recorded as the DUDA tip-to-apex distance (TAD). Rater reliability was determined using the intraclass correlation coefficient.

RESULTS

We found DUDAs in 94% of radiographs. The mean DUDA angle was 5.6° ± 2.6° and the mean TAD was 45.3 ± 9.5 mm. The Pearson correlation coefficients for side-to-side comparisons were 0.47 for the DUDA angle and 0.69 for the TAD. For male and female patients, the mean DUDAs were 5.4° ± 2.3° and 5.9° ± 2.9°, respectively, and the mean TADs were 47.8 ± 9.7 mm and 41.7 ± 7.9 mm, respectively. The DUDA angle and TAD had negligible associations with age (r = -0.15 and -0.08, respectively). At 0.74 (95% CI, 0.58-0.85), interrater reliability was good. At 0.93 (95% CI, 0.88-0.96), intrarater reliability was excellent.

CONCLUSIONS

We demonstrated DUDAs, representing valgus deviations from the center axis and anteroposterior views of the ulna. Contralateral lateral wrist radiographs are moderate to strongly reliable in determining a DUDA. Rater reliability was good to excellent.

CLINICAL RELEVANCE

Re-creation of the DUDA may benefit procedures such as ulnar shortening osteotomy, fractures, or malunion by contributing to knowledge of distal radioulnar joint biomechanics.

Radiographic changes in the distal ulna in non-rheumatoid patients with extensor digitorum communis ruptures

INTRODUCTION

Osteoarthritis of the distal radioulnar joint (DRUJ) is relatively common in elderly people. Extensor digitorum communis (EDC) ruptures occasionally and occurs with or without prior signs in these people. The purpose of this study was to clarify the radiographic changes in the distal ulna associated with EDC rupture.

MATERIALS AND METHODS

We analyzed plain radiographs of 71 patients with non-rheumatoid arthritis and 40 controls. Radiographic changes in the distal ulna were categorized into normal, osteoarthritic-change (OA-change), and taper. We measured the ulnar variance (UV) and ulnar bowing angle in the posteroanterior radiographs and the dorsal bowing angle (DBA) and dorsal protrusion (DP) in the lateral radiographs. The shape of the sigmoid notch (SN) was categorized into flat, radial inclination, and dimple. The primary outcome was a comparison of radiographic parameters between the patient and the control groups. The secondary outcome was an analysis of the type of SN to investigate factors affecting ulnar deformation.

RESULTS

The ratio of the radiographic change in the ulna, UV, DBA, and DP was significantly larger in the patient group than in the control group. Patients with the radial inclination type of SN showed a greater UV than those with the dimple type.

CONCLUSIONS

Deformation of the distal ulna, a large UV, dorsal penetration, and dorsal bowing was related to EDC rupture. Regarding the large UV, the lunate shaved the upper half of the distal ulna, whereas the DRUJ shaved the lower half. These processes formed a tapered ulna head. A large UV and an inclination of the DRUJ played a role in ulnar head deformation.

Morphologic Characteristics of the Sigmoid Notch of the Distal Radius for Patients With Peripheral Triangular Fibrocartilage Complex Tear

The distal radioulnar joint (DRUJ) is stabilized by the bony anatomy of the contact surfaces. The authors analyzed the morphologic characteristics and radiologic parameters at the sigmoid notch of patients with a peripheral triangular fibrocartilage complex (TFCC) tear compared with asymptomatic patients. Preoperative axial computed tomography scans were reviewed for 76 wrists with peripheral TFCC injuries, including foveal avulsion, and 76 wrists of age- and sex-matched control subjects. The authors used axial computed tomography scans of the DRUJ to classify the patients into 4 groups according to the type of sigmoid notch, namely, flat face, ski-slope, C-type, and S-type. They also measured the tilting angle, depth, width of the sigmoid notch, and radioulnar ratio (RUR). Statistical analyses were performed with the chi-square test or paired t test (P<.05). The mean proportions of flat face, ski-slope, C-type, and S-type sigmoid notches among patients with peripheral TFCC injuries were 42%, 22%, 29%, and 7%, respectively, whereas those for the control group were 33%, 1%, 65%, and 1%, respectively (P<.05). The tilting angle was lower (TFCC injury, 84.5°; control, 86.2°; P<.05) and the RUR was significantly higher (TFCC injury, 0.67; control, 0.56) in the TFCC group, particularly for men (P<.05). Depth (TFCC injury, 1.0 mm; control, 1.3 mm; P>.05) and width (TFCC injury, 14.8 mm; control, 14.5 mm; P>.05) were similar between the groups. Patients with ski-slope or dorsally tilted sigmoid notches may be at greater risk for peripheral TFCC injuries. [Orthopedics. 2021;44(6):e729-e734.].

Contribution of a distal radioulnar joint stabilizer on forearm stability: A modeling study

Instability of the forearm is a complex problem that leads to pain and limited motions. Up to this time, no universal consensus has yet been reached as regards the optimal treatment for forearm instability. In some cases, conservative treatments are recommended for forearm instability injuries. However, quantitative studies on the conservative treatment of forearm instability are lacking. The present study developed a finite element model of the forearm to investigate the contribution of the distal radioulnar joint stabilizer on forearm stability. The stabilizer was designed to provide stability between the radius and ulna. The forearm model with and without the stabilizer was tested using the pure transverse separation and radial pull test for the different ligament sectioned models. The percentage contribution of the stabilizer and ligament structures resisting the load on the forearm was estimated. For the transverse stability of the forearm, the central band resisted approximately 50% of the total transverse load. In the longitudinal instability, the interosseous membrane resisted approximately 70% of the axial load. With the stabilizer, models showed that the stabilizer provided the transverse stability and resisted almost 1/4 of the total transverse load in the ligament sectioned models. The stabilizer provided transverse stability and reduced the loading on the ligaments. We suggested that a stabilizer can be applied in the conservative management of patients who do not have the gross longitudinal instability with the interosseous membrane and the triangular fibrocartilage complex disruption.

Three-Dimensional Automated Assessment of the Distal Radioulnar Joint Morphology According to Sigmoid Notch Surface Orientation

PURPOSE

To develop reproducible 3-dimensional measurements for quantification of the distal radioulnar joint (DRUJ) morphology. We hypothesized that automated 3-dimensional measurement of the ulnar variance (UV) and the sigmoid notch (SN) angle would be comparable to those of the reference standard while overcoming some drawbacks of conventional 2-dimensional measurements.

METHODS

Radiological data of healthy forearm bones (radiographs and computed tomography) of 53 adult subjects were included in the study. Automated measurements were developed for assessment of the SN morphology based on 3-dimensional landmarks, incorporating subject-specific estimation of cartilage surface orientation. A common anatomical reference was defined among the different imaging modalities and a comparison of the SN angle and UV measurements was performed in radiographs, computed tomography scans, and 3-dimensional models. Finally, the 3-dimensional UV measurements were evaluated in an experimental setup using 3-dimensional printed bone models.

RESULTS

The automated 3-dimensional measurements of SN subtypes showed a notably larger notch radius (18.9 mm) for negative SN angles compared with positive SN angles in subjects (16.9 mm). Similar UV measurements were obtained in healthy DRUJ morphologies, with a high correlation between radiographs and 3-dimensional measurements for the SN angle (0.77) and UV (0.85). In the experimental setup with pathological radial inclinations, UV was on average 1.13 mm larger in the radiographs compared with the 3-dimensional measurements, and 1.30 mm larger in the cases with pathological palmar tilts. Furthermore, UV radiograph measurements on the modified palmar tilt deviated from the 3-dimensional measurements.

CONCLUSIONS

The developed 3-dimensional automated measurements were able to quantify morphological differences among sigmoid notch subtypes and were comparable to those of the reference standard.

CLINICAL RELEVANCE

The developed methods do not depend on the forearm position or orientation of the distal radius and can be used for 3-dimensional quantification of DRUJ pathologies in 3-dimensional surgical planning.

Outcomes after anatomic reconstruction of the radioulnar ligaments for distal radioulnar joint instability

This retrospective study investigated the clinical outcomes of patients treated for chronic distal radioulnar joint instability with open anatomic reconstruction of the palmar and dorsal radioulnar ligaments. After the midpoint of a tendon graft is anchored at the ulnar fovea, the two graft limbs traverse the distal radioulnar joint. One limb is woven into the palmar wrist capsule and the other is secured to the dorsal wrist capsule and retinaculum to stabilize the joint. Of 30 patients (31 wrists) treated with this technique, 19 were followed longitudinally for a mean of 10 years (range 3-21). In this long-term cohort, there were statistically significant improvements in ulnar-sided wrist pain on the visual analogue scale and in distal radioulnar joint stability on the dorsopalmar stress test. The modified Mayo Wrist Scores were classified as three excellent, 12 good, three fair and one poor. Of the 30 patients studied, failure occurred in four patients, two from graft rupture and two from distal radioulnar joint arthrosis. We conclude that anatomic reconstruction of the palmar and dorsal radioulnar ligaments is an effective treatment for distal radioulnar joint instability and is associated with high satisfaction and durable outcomes.Level of evidence: IV.

Melone's concept revisited in comminuted distal radius fractures: the three-dimensional CT mapping

Background

There is no consensus in the literature about the ideal classification of the distal radius fracture for the clinical practice. The traditional Melone classification system divides the distal radius into four basic components, the shaft, radial styloid, dorsal medial fragment, and volar medial fragment. The aim of this study was to identify fracture lines in comminuted distal radius fractures using three-dimensional mapping of computed tomography (CT) images to test the hypothesis that fracture fragments can be divided according to the Melone classification.

Methods

Fifty-nine consecutive OTA/AO 23C3 fractures presented at the hospital between January 2018 and October 2019 were retrospectively reviewed. The fracture lines were characterized in the axial, sagittal, and coronal CT planes. After reducing the fractures in a three-dimensional (3D) model, the fracture lines were plotted from the CT images and were then superimposed on one another and oriented to fit a standard template. The area of articular surfaces was measured and compared to quantify the differences between the radial bone fragments.

Results

Thirty-five cases (59.3%) in this study fit the Melone classification and 24 cases (40.7%) did not. On the radiocarpal surface, there was a greater concentration of fracture lines in the dorsal area of the radius than in the volar area. On the distal radioulnar joint (DRUJ), the fracture lines were focused around two specific concentrated regions. For the articular surface area, the mean area of the radial styloid, volar medial fragment, and dorsal medial fragment was 141.13 ± 90.16 mm², 147.79 ± 75.94 mm², and 79.05 ± 70.73 mm², respectively. There was a significant difference in articular surface area for the Melone fragments (P = 0.002).

Conclusions

The Melone classification system is not suitable for characterizing all C3 fractures. The findings of this study confirm that the dorsal medial fragments are relatively comminuted and small. Extra care should be given to these small fragments when reducing the fracture.

Image-Based Comparison Between the Bilateral Symmetry of the Distal Radii Through Established Measures

PURPOSE

Anthropometric assessment of bony structures in the body is important for preoperative computer-aided surgery, implant design, finite element modeling, and biomechanical studies investigating joint structure and function. The use of the contralateral limb in surgery and clinical practice relies on the assumption that the right and left limbs of an individual are symmetric. Therefore, the purpose of this study was to quantify the bilateral symmetry of the bony structures of the distal radius using 3-dimensional (3D) computed tomography.

METHODS

We collected computed tomography images of 37 paired, fresh-frozen, healthy cadaveric male upper limbs (aged 75.4 ± 8.3 years). Three-dimensional reconstructed models were created using semiautomatic segmentation. Using the 3D models, we measured 3D radial inclination, 3D volar tilt, 3D radial height, medial volar cortical angle, middle volar cortical angle, and lateral volar cortical angle and compared them between sides.

RESULTS

There were no statistically significant differences measured between right and left distal radius in 37 paired wrists. Mean radial height was 12.81 mm (SD, 1.74 mm) on the left and 12.88 mm (SD, 1.72 mm) on the right. Mean volar tilt was 10.74° (SD, 3.74°) and 10.77° (SD, 3.19°) and radial inclination was 24.05° (SD, 2.63°) and 24.18° (SD, 3.41°) on the left and right, respectively. Mean volar cortical angle across the radius was 140.9° (SD, 7.9°) on the left and 140.1° (SD, 7.9°) on the right.

CONCLUSIONS

Direct bilateral comparison of the distal radius and wrist joints is useful to predict normal anatomy of the injured radius, because bilateral similarities exist.

CLINICAL RELEVANCE

This article provides a comprehensive list of measurements of the distal radius compared bilaterally using a 3D model. From this study, we found that the contralateral radius can be used as a benchmark with which to compare fracture reduction and to manage malunions during the preoperative planning of corrective osteotomies. It can also be used to define normal anatomy.

A three-dimensional virtual morphometry study of the sigmoid notch of the distal radius

PURPOSE

Our primary objectives were to create a reliable, noninvasive method for three-dimensional morphometry of deep bony parameters within the sigmoid notch of the distal radius, to identify its morphological patterns, and to identify any significant variation between the left and the right wrists. Our secondary objectives were to obtain morphometric values that could represent our population and to identify any possible ethnic variations.

METHODS

Computed tomography scans of 102 wrists from 51 healthy individuals were analyzed using a virtualization software. Four anatomical parameters at the distal radius sigmoid notch, namely, the radius of curvature, depth, version angle, and sagittal slope were measured. Morphological patterns of the sigmoid notch surface were identified. The results were statistically analyzed to assess the reliability of the technique and were compared with previously published literature.

RESULTS

Comparing our findings with previously published values, our study revealed a slightly larger radius of curvature and sagittal slope, while revealing a smaller depth and version. We identified the S-type, C-type, and ski-slope morphological variants. The flat-face morphological variant, however, was not identified. The sigmoid notch at the left and right wrists were similar, except for the radius of curvature.

CONCLUSION

This study demonstrates a noninvasive, fast, reliable, and reproducible technique for analyzing the sigmoid notch of the distal radius. In wrist injuries with intact distal radius sigmoid notch but involving comminuted fractures of the ulnar head, ulnar head replacement may be indicated. In such cases, analysis of the ipsilateral intact sigmoid notch would allow us to prepare an ulnar head prosthesis of appropriate size.

An In Vitro Study to Determine the Effect of Ulnar Shortening on Distal Forearm Loading During Wrist and Forearm Motion: Implications in the Treatment of Ulnocarpal Impaction

PURPOSE

To evaluate the effect of ulnar shortening on distal forearm loading following simulated dynamic motion.

METHODS

Ulnar shortening was simulated using a custom-built adjustable implant to simulate up to 4 mm of ulnar shortening (-4 mm) in 9 cadaveric extremities. Load cells were placed in the distal ulna and radius to quantify axial loading. Using a wrist and forearm motion simulator, absolute and percentage loads were measured during dynamic flexion, ulnar deviation (UD), flexion dart throw (DT), and pronation.

RESULTS

There was a significant decrease in absolute and percentage distal ulnar loads at each interval of ulnar shortening during flexion, UD, DT, and pronation. The distal ulna bore no compressive loads, and in fact, tensile loads were measured in the ulna at 2 mm of ulnar shortening during DT and pronation, at 3 mm during flexion, and at 4 mm during UD.

CONCLUSIONS

A progressive decrease in distal ulnar loads with generation of tensile loads was observed with sequential ulnar shortening.

CLINICAL RELEVANCE

Ulnar shortening greater than 2 mm can result in tensile loading in the distal ulna. When managing ulnar impaction syndrome, excessive shortening may not be required to provide relief of symptoms.

Distal radioulnar joint configurations in three-dimensional computed tomography in patients with idiopathic ulnar impaction syndrome

We retrospectively reviewed 26 patients diagnosed with idiopathic ulnar impaction syndrome and measured the slopes of the sigmoid notch and ulnar head at their centre using their preoperative three-dimensional computed tomography. We found that the slope of the sigmoid notch and that of the ulnar head were not parallel to each other. There was a significant linear relation between the slope of the ulnar head and the changes in the closest joint space of the distal radioulnar joint at the centre of the sigmoid notch after ulnar shortening. We conclude that the slope of the ulnar head is more strongly correlated with changes in the closest joint space in the distal radioulnar joint than that of the sigmoid notch. Our findings suggest that slope of the ulnar head might be as important a predisposing factor as that of the sigmoid notch for the progression of distal radioulnar joint arthritis after ulnar-shortening osteotomy. We should consider the slopes of both the sigmoid notch and ulnar head before the osteotomy. Level of evidence: IV.

Apparent Proximal Ulna Dorsal Angulation Variation Due to Ulnar Rotation

OBJECTIVE

To investigate the effect of ulna rotation on the apparent proximal ulna dorsal angulation (PUDA).

METHODS

Computed tomography images of 59 ulnas were included in this study, 48 being bilateral specimens and the remaining 11 were unilateral. Three-dimensional models of the entire ulna were obtained, and the ulnas were rotated in 5-degree increments in internal rotation or external rotation from neutral. PUDA, PUDA apex, varus angulation, and varus apex were measured on each ulna.

RESULTS

With the ulna in neutral rotation, the mean (95% CI) PUDA was 3.7 (2.9-4.5) degrees, whereas the mean varus angle was 10.5 (9.8-11.1) degrees. The varus angle apex and PUDA apex were 28.9 (27.5-30.2)% and 19.6 (18.7-20.6)% along the total length of the ulna, respectively. As the ulna was rotated externally by 5, 10, and 15 degrees, the PUDA increased by 0.7 (0.5-0.9) degrees, 1.2 (0.9-1.4) degrees, and 1.4 (1.1-1.8) degrees, respectively. Conversely, with internal rotation of 5, 10, and 15 degrees, the PUDA decreased by 0.9 (0.8-1.1) degrees, 2.0 (1.8-2.3) degrees, and 3.3 (2.7-3.9) degrees, respectively.

CONCLUSIONS

This study demonstrates that small degrees of ulna rotation result in a statistically significant change in the apparent PUDA; however, this may not represent a clinically significant difference. Because of the anatomic variation between patients, it is important to obtain a contralateral film to determine the PUDA for anatomic reduction of the ulna in complex cases. When using a contralateral image, it is important to obtain a true lateral film or consider using 3-dimensional imaging for preoperative planning.

A Biomechanical Perspective on Distal Radioulnar Joint Instability

Background The purpose of this article was to review the anatomy, kinematics of the distal radioulnar joint (DRUJ), and to discuss definition, classification, and diagnosis of DRUJ instability. Methods A biomechanical perspective on physical examination of DRUJ ballottement test was documented. Physiological dynamic DRUJ translation and differences of the translation following sequential ligament sectioning and changes in different forearm and wrist positions were demonstrated. The clinical significance of each ligament's contribution to joint stability in specific wrist positions was addressed. Conclusion Each ligament stabilizing the DRUJ contributed to joint stability depending on the direction (palmer or dorsal) and different positions of the wrist and forearm. DRUJ ballottement test in each wrist and forearm position may detect tears of specific ligament stabilizing the DRUJ.

[Treatment of traumatic ulnar styloid impaction syndrome by Sauvé-Kapandji procedure]

Objective

To evaluate the effectiveness of Sauvé-Kapandji procedure in the treatment of traumatic ulnar styloid impaction syndrome.

Methods

Between June 2010 and January 2013, 12 patients with traumatic ulnar styloid impaction syndrome were treated by Sauvé-Kapandji procedure. There were 4 men and 8 women, with an average age of 58.9 years (range, 50-69 years). The disease was caused by traffic accident in 1 case, and by falling from height in 11 cases. All patients had dislocation of the distal radioulnar joint, and 7 patients also had old fractures of the distal radius. The main clinical symptoms were pain and limited activity of the wrist joint, and the disease duration was 2-4 months (mean, 3.5 months). The visual analogue scale (VAS) was 6.2±1.4. The clinical outcomes were assessed by VAS, range of motion (ROM) of the wrist, grip strength, Evans score, and X-ray film of wrist joint during follow-up.

Results

All patients obtained healing of incision by first intention and were followed up 37-73 months (mean, 58.4 months); no complication of infection, blood vessel injury, or nerves injury occurred. VAS was 1.2±1.0 at the final follow-up, showing significant difference when compared with preoperative one ( t=9.950, P=0.000). The ROM of the affected wrist joint in flexion, extension, ulnar deviation, forearm pronation and supination were improved, but the ROM of the affected side were significantly less than those of normal side ( P<0.05). No significant difference was found in the grip strength and Evans score between the affected side and normal side ( t=-0.885, P=0.386; t=-1.969, P=0.062). According to Evans scores, the results were excellent in 8 cases, good in 3 cases, and fair in 1 case, with an excellent and good rate of 91.7%. Postoperative radiographs showed bony healing in all patients, with the average healing time of 3.5 months (range, 3-6 months). The instability of proximal ulna occurred in 3 cases.

Conclusion

Sauvé-Kapandji procedure is a reliable remedy method for traumatic ulnar styloid impaction syndrome, with favorable improvement in wrist pain and forearm rotation. However, the surgical indications for Sauvé-Kapandji procedure should be strictly controlled.