Treatment of subacute/chronic ECU tendinopathy using wrist arthroscopy and open surgical repair

PURPOSE

To report the arthroscopic and clinical findings of patients with extensor carpi ulnaris (ECU) tendinopathy treated with wrist arthroscopy and open surgical repair.

METHODS

We retrospectively reviewed the medical records of seven patients with chronic ECU tendinopathy who were treated with diagnostic wrist arthroscopy and open surgical repair between 2010 and 2017. Seven cases diagnosed with ECU tendinopathy had undergone open procedure for the ECU tendinopathy, as well as wrist arthroscopy in the same session. Any pathology of the triangular fibrocartilage complex (TFCC) diagnosed by wrist arthroscopy were treated simultaneously with open procedure for the ECU tendinopathy. The functional outcome was evaluated by comparing the preoperative and final follow-up values of range of motion (ROM), grip strength, visual analog scale (VAS) for pain, modified Mayo wrist score and quick disabilities of the arm, shoulder, and hand (DASH) score.

RESULTS

TFCC tears were identified in four patients of which repair was performed concomitantly. The average follow-up period was 39 months (range, 25-49 months). At the final follow-up, all the outcomes including average VAS score (6.4→1), the ROM (173→192°), quick DASH score (42.5→18.2), and modified Mayo wrist score (48.6→79.3) improved significantly.

CONCLUSION

When treating patients with ECU tendinopathy, the possibility of TFCC combined injury should always be considered. If surgical treatment is planned, we suggest a wrist arthroscopy for more accurate diagnosis an intra-articular pathology, particularly for patients whose MRI findings suggest a degenerative tear or degeneration at the periphery of the TFCC. Additionally, if ECU and DRUJ stability is obtained by repair or reconstruction of the concurrent pathologies in the ECU subsheath, TFCC and other intra-articular structures, the results will be favorable.

Anatomical Study of Stabilizing Structures of the Extensor Carpi Ulnaris Tendon Around the Wrist

PURPOSE

The sixth dorsal extensor compartment is a relatively common site of stenosing tenosynovitis in the upper extremity, but the exact location of stenosis is not fully understood. The objective of this study was to investigate the detailed anatomy of structures surrounding the extensor carpi ulnaris (ECU) tendon around the wrist.

METHODS

Fifty fresh human cadaveric wrists were used for gross observation and morphology measurements of the sixth dorsal compartment and the ECU subsheath. An additional 13 wrists were used for histological examination. We evaluated the morphology of supporting structures in 3 regions: the ulnar groove (zone I), the ulnar styloid process (zone II), and the triquetrum (zone III).

RESULTS

The fibro-osseous tunnel comprising the ulnar groove and the overlying subsheath (zone I) stabilized the ECU tendon, and the subsheath had thin membranous collagen fibers attached to the periosteum. We consistently found the distal extension of ECU subsheath (zone II), which connected the ulnar styloid process and the dorsal radioulnar ligament. Variations in the length of the distal extension increased with the forearm in pronation. Collagen fiber thickness around the ECU tendon in zone II was greater than that of zone I. In zone III, the overlying extensor retinaculum and septa, which were composed of thick circumferential collagen structures, supported the ECU tendon by attaching to the triquetrum on both sides of the ECU tendon. We found the presence of an ulnar septum of the sixth compartment attached to the triquetrum in 84% of dissected wrists.

CONCLUSIONS

The ECU tendon was supported by the ECU subsheath, which had thin and elastic collagen fibers over the ulnar groove. Distal extension of the subsheath and surrounding radial and ulnar extensor retinaculum septa attached to the triquetrum provided thicker supporting structures.

CLINICAL RELEVANCE

Stenosing ECU tenosynovitis may occur not only in the ulnar groove but also in the more distal ulnar styloid process and triquetrum areas.

Subluxation of the extensor carpi ulnaris on magnetic resonance imaging on neutral wrist position: correlation with tenosynovitis of the extensor carpi ulnaris and translation of the distal radioulnar joint

OBJECTIVE

To identify the subluxation degrees of extensor carpi ulnaris (ECU) tendon on neutral wrist MRI in patients with ulnar-sided wrist pain and to evaluate the relationships of ECU subluxation with accompanying imaging findings such as ECU tenosynovitis, distal radioulnar joint (DRUJ) stability, and triangular fibrocartilage complex (TFCC) pathology.

MATERIALS AND METHODS

A total of 297 MRIs of 292 patients having ulnar side pain were reviewed retrospectively. Degrees of ECU subluxation was classified into four grades: grade 0, no subluxation; grade 1, tendon displacement < 50% of the tendon width; grade 2, tendon displacement 51 to 99% of the tendon width; and grade 3, tendon displacement of 100% of the tendon width. ECU tenosynovitis, ECU tendinosis, injuries of triangular fibrocartilage and distal radioulnar ligaments (DRUL), translation ratio of the DRUJ, rotation angle of the DRUJ, and the width, depth, and length of the ulnar groove were assessed on wrist MRI. The relationships between degree of ECU subluxation and these imaging findings were investigated.

RESULTS

Women had higher subluxation degrees of the ECU tendon (p = 0.001). Tenosynovitis of the ECU, sprain of the dorsal DRUL, dorsovolar translation ratio and rotation angle of the DRUJ, and depth and length of the ulnar groove were statistically significantly related to the subluxation degree of the ECU tendon (p = 0.000).

CONCLUSION

High-grade subluxation of the ECU tendon was strongly correlated with ECU tenosynovitis and DRUJ translation. Clinicians and radiologists should scrutinize imaging findings, particularly when patients with ulnar-sided wrist pain have high-grade subluxation of the ECU tendon.

"Snapping" of the extensor carpi ulnaris tendon in asymptomatic population

Background

Extensor carpi ulnaris tendinopathy (ECU) can be one cause of ulnar side wrist pain and it is more prominent in pronation-supination movements against resistance. In supination, flexion, and ulnar deviation within the ulnar groove, the tendon is tense and becomes predisposed to subluxation or dislocation. Snapping occurs during this dislocation and relocation. As a result of this friction between the tendon sheath and ulnar groove, tendinopathy and pain occur. ECU tendon is an important structure that contributes to the dynamic stability of wrist therefore resulting degeneration contributes disruption of distal radioulnar joint and causes wrist instability.

Methods

Participants without active wrist complaints who presented to the outpatient clinic between 2019 and 2020 were included. Provocation test was performed and participants with snapping were evaluated with ultrasound to determine subluxation or dislocation. Participants asked to indicate approximately how much time they spent daily on the phone, computer and game console. The distribution of data was evaluated with the Kolmogorov-Smirnov test. Quantitative data that were not normally distributed were evaluated using the Mann-Whitney U test, and Student’s t-test was used for normally distributed data. The Chi-square test was used to compare categorical variables. For all tests, p < 0.05 was considered statistically significant.

Results

Four hundred and fifteen women and 340 men were included in the study. Fifty of the 755 participants (6.6 %) had snapping. 22 of the 755 participants (2.9 %) had dislocation or subluxation on ultrasound. Three (13.6 %) participants had dislocation and 19 (%86.4) participants had subluxation on ultrasound. All 50 of the participants with snapping had significant repetitive trauma and sports activities. It was determined that 21 of the 22 participants who were found to have subluxation or dislocation by ultrasound had more than two hours of hobby activity and significantly more participants had more than two hours of activity compared to the group without subluxation or dislocation.

Conclusions

This study with a large number of participants will contribute to the literature in terms of evaluating the contribution of technological devices, such as computers, smartphones, and consoles to chronic wrist pain and the prevalence of ECU snapping in the asymptomatic population.

Trial registration

Date of Approval; 19.02.2019, Approval Number; 19-KAEK-045.

Oligosynaptic inhibition mediated by group Ia afferents from flexor digitorum superficialis to wrist flexors in humans

Effects of low-threshold afferents from the flexor digitorum superficialis (FDS) to the flexor carpi radialis (FCR), flexor carpi ulnaris (FCU) and extensor carpi ulnaris (ECU) motoneurons were examined using a post-stimulus time-histogram (PSTH) and electromyogram-averaging (EMG-A) methods in seven healthy human subjects. Electrical conditioning stimulation to the median nerve branch innervating FDS with the intensity immediately below the motor threshold was delivered. In the PSTH study, the stimulation produced a trough (inhibition) in 19/44 (43%) of FCR and 17/41 (41%) of FCU motor units. Remaining motor units received no facilitatory and inhibitory effects. The central latency of the inhibition was 1.1 ± 0.6 ms (mean ± SD) and 0.6 ± 0.4 ms longer than that of the homonymous monosynaptic Ia facilitation of FCR and FCU, respectively. In the EMG-A study, the stimulation produced a trough (inhibition) in EMG-A of FCR and FCU in all the seven subjects. Amount of the inhibition was 14.5 ± 3.8% (FCR) and 17.9 ± 2.5% (FCU). Since the inhibition diminished after withdrawal of tonic vibration stimuli to the FDS muscle belly, group Ia afferents should be responsible for the inhibition. The stimulation did not produce facilitatory or inhibitory effect on ECU motoneurons in both the PSTH and EMG-A studies. These findings suggest that group Ia afferents from FDS inhibit excitability of motoneurons supplying FCR and FCU through an oligo (di- or tri-) synaptic path in the spinal cord. The reflex arcs would function to prevent wrist flexion during hand grasping movements.

Anthropometric and clinical analysis of the distal ulna and extensor carpi ulnaris tendon using MRI

OBJECTIVE

To investigate the ulnar groove (UG), extensor carpi ulnaris (ECU) tendon, and ulnar styloid process (USP) parameters in asymptomatic individuals without ulnar-sided wrist abnormalities, to determine whether these values can be anthropometric markers of age and gender and identify their correlations for use in clinical decision-making.

MATERIALS AND METHODS

The MRI T1W axial, T2W sagittal, coronal PW and DESS sequences were evaluated in 100 cases (62 women). The UG width, depth and groove opening angle (GOA), ECU tendon width and thickness, and USP base width and length were measured.

RESULTS

For gender, the cut-off, sensitivity, specificity and accuracy values were 8.58 mm, 67, 68 and 66%, respectively, for UG width; 5.3 mm, 53, 68 and 62%, respectively, for ECU width; and 6.4 mm, 55, 74, and 67%, respectively, for USP length. There was no difference concerning age. The tendon width was 63% of the UG width and depth was approximately 51% out of the UG. UG depth was correlated with GOA and tendon thickness (p < 0.001 and 0.03, respectively); UG width with GOA, tendon thickness, and USP base width and length (p = 0.005, 0.01, 0.016, and 0.02, respectively); tendon width-thickness with USP base width and length (p = 0.05); and US base width with US length (p < 0.001).

CONCLUSION

The gender differences in distal ulnar measurements can be beneficial for surgery and forensic science. UG is wider than ECU tendon, and this is the cause of normal subluxation. Therefore, rather than deepening UG, surgeons should focus on tendon sheath abnormalities as a physiological solution.

A Biomechanical Comparison of Extensor Carpi Ulnaris Subsheath Reconstruction Techniques

PURPOSE

Several surgical stabilization techniques have been described to address pathological subluxation of the extensor carpi ulnaris (ECU) tendon, with no comparative data available. This study compares ECU stability after subsheath reconstruction, with and without ulnar groove deepening, to stability with an intact subsheath in a cadaveric model.

METHODS

Position of the ECU tendon relative to the ulnar groove was measured in 5 human cadaveric specimens with the subsheath intact, sectioned, and after 3 reconstruction scenarios: reconstructed, reconstructed with ulnar groove deepened, and ulnar groove deepened with subsheath sectioned. Position of the tendon relative to the radial side of the ulnar groove was recorded with digital calipers in 9 combinations of wrist/forearm positions (wrist flexion, extension, and neutral; forearm pronation, supination, and neutral). Dislocation events, defined as the tendon being completely ulnar to the groove, were recorded.

RESULTS

Extensor carpi ulnaris tendon displacement was not significantly different between intact subsheath, subsheath reconstruction, and reconstruction with groove deepening (1.5 mm vs 0.5 mm vs -0.3). Extensor carpi ulnaris tendon displacement after groove deepening with the subsheath sectioned was not significantly different from displacement with a fully sectioned subsheath. Sectioning of the subsheath induced dislocation events of the ECU tendon in multiple positions. Subsheath reconstruction with and without groove deepening allowed no dislocation events.

CONCLUSIONS

In this cadaveric model, groove deepening did not improve stability of the ECU tendon compared with the reconstructed subsheath, and reconstruction alone was equally effective at eliminating dislocation events.

CLINICAL RELEVANCE

Stabilization techniques that focus on restoration of the important ulnar attachment of the ECU subsheath are favored over routine deepening of the ulnar groove in attempts to stabilize the ECU tendon.

Extensor Carpi Ulnaris Subsheath Reconstruction

Acute extensor carpi ulnaris (ECU) subsheath injury and chronic subsheath insufficiency may result in symptomatic ECU instability at the level of the distal ulna osseous sulcus. Associated ulnocarpal (ie, triangular fibrocartilage complex) and ECU intrinsic tendinopathic changes may accompany subsheath pathologies and require concomitant treatment. Surgical treatment is indicated in refractory cases despite nonoperative treatment and may consist of repair of the torn edge of the ECU subsheath or, more frequently, reconstruction utilizing a radially based extensor retinacular sling. An ECU subsheath reconstructive technique is detailed.

Relative Contribution of the Subsheath to Extensor Carpi Ulnaris Tendon Stability: Implications for Surgical Reconstruction and Rehabilitation

PURPOSE

To identify the varying contributions of the proximal and distal portions of the subsheath of the extensor carpi ulnaris (ECU) to its stability, evaluate the correlation of ulnar groove depth and ECU subluxation, and observe the effect of forearm and wrist positions on ECU stability.

METHODS

Extensor carpi ulnaris tendon position relative to the ulnar groove was measured in 10 human cadaveric specimens with the subsheath intact, partially sectioned (randomized to distal or proximal half), and fully sectioned. Measurements were obtained in 9 positions: forearm supinated, neutral, and pronated and wrist extended, neutral, and flexed. Ulnar groove depth was measured on all specimens.

RESULTS

In 7 of 10 specimens with an intact subsheath, the ECU tendon subluxated out of the groove in at least 1 forearm-wrist position. We noted the subluxation of the ECU tendon in all wrist-forearm positions with the exception of pronation-extension in at least 1 specimen. For partial subsheath sectioning, tendon displacement markedly increased after distal subsheath sectioning but not after proximal sectioning. For full subsheath sectioning, wrist flexion produced subluxation in all forearm positions, and forearm supination produced subluxation in all wrist positions. Maximum displacement occurred in supination-flexion. There was no correlation between ulnar groove depth and ECU subluxation.

CONCLUSIONS

Mild tendon subluxation occurred in the intact specimens in most tested positions. Two positions were remarkable for their consistency in maintaining the tendon within the groove: pronation-neutral and pronation-extension. In fully sectioned specimens, the greatest subluxation occurred in supination-flexion, with supination and flexion independently producing subluxation. Partial sectioning demonstrated that the distal portion of the subsheath played a more important role than the proximal portion in stabilizing the ECU.

CLINICAL RELEVANCE

Subsheath repair or reconstruction should target the distal portion of the subsheath. During postinjury rehabilitation or following surgical reconstruction, combined forearm supination and wrist flexion should be avoided.

Incidental signal changes in the extensor carpi ulnaris on MRI

BACKGROUND

Magnetic resonance imaging (MRI) commonly finds musculoskeletal abnormalities incidental to the reason for ordering the test. The purpose of this study was to determine if the prevalence of extensor carpi ulnaris (ECU) signal changes on MRI varies between patients undergoing upper extremity MRI for assessment of clinically suspected ECU tendinopathy and those undergoing upper extremity MRI for other indications. Our secondary null hypotheses were that the prevalence of ECU signal changes on MRI does not vary based on patient age or sex and that the prevalence of ECU signal changes on MRI does not vary among other indications for MRI.

METHODS

We searched MRI reports of all patients undergoing MRI of the hand, wrist, or arm at our institution between 2001 and 2014 for signal changes in the ECU. The medical record was reviewed to determine the indication for the MRI and the presence of clinically suspected ECU tendinopathy.

RESULTS

ECU signal changes (overall prevalence of 13 %) were more common in patients undergoing MRI for a working clinical diagnosis of ECU tendinopathy or ulnar-sided wrist pain compared to patients evaluated for nonspecific pain and other indications. Age was independently associated with ECU signal changes on MRI. MRI signal changes are uncommonly associated with symptomatic tendinopathy (low positive predictive value).

CONCLUSIONS

ECU signal changes on MRI are common and often asymptomatic.

Morphology of the extensor carpi ulnaris groove and tendon

PURPOSE

Injury to the extensor carpi ulnaris (ECU) fascial supports on the distal ulna can result in ulnar-sided wrist pain, particularly when the tendon subluxates medially out of the fibroosseous groove with forearm rotation. To better understand the potential risk factors for injury and the indications for modifying the ECU groove, we have evaluated and quantified the morphology of the ECU groove and tendon.

METHODS

Axial plane magnetic resonance imaging of the wrist obtained for triangular fibrocartilage complex and intercarpal pathology in 60 patients were reviewed. Mean and standard error of the mean were calculated and unpaired Student t tests performed to compare groove width and depth, radius of curvature of the groove, carrying angle, and tendon-to-groove ratio.

RESULTS

There were 23 females (38%), and the mean patient age was 40 years (range, 17-71 y). The average ECU groove depth and standard error of the mean was 1.4 mm ± 0.1 mm. The radius of curvature for the ulnar ECU groove was found to be 7.0 mm ± 0.4 mm with a carrying angle of 143° ± 2°. In neutral forearm rotation, the average ratio of the width of the ECU tendon to groove was 0.7 ± 0.02. The data approximated a normal distribution. There were no statistically significant differences in these measurements between the triangular fibrocartilage complex and the intercarpal pathology subgroups.

CONCLUSIONS

Variability in the relationship of the ECU groove and tendon may combine to represent risk factors for tendinosis or tendon subluxation. There may be a more normal distribution of ECU groove morphology than previously recognized.

CLINICAL RELEVANCE

ECU injuries may require clinical imaging of the tendon and subsheath, in addition to potential surgical reconstruction and ulnar groove deepening. This report establishes the normative morphology and depth of the ECU groove and provides a comparative baseline when considering treatment modalities.

An experimental study

STUDY DESIGN

Experimental laboratory-based research in biomechanics.

INTRODUCTION

The mechanisms by which some lunotriquetral (LTq) ligament disruptions remain stable are not known.

PURPOSE OF THE STUDY

To investigate the contribution of muscles in preventing carpal destabilization when the LTq ligaments are torn.

METHODS

Ten fresh cadaver wrists, set vertical in a jig, were isometrically loaded through five wrist motor tendons. Changes in carpal alignment secondary to the application of loads were monitored by a Fastrak™ electromagnetic motion tracking device, before and after sectioning the LTq ligaments.

RESULTS

After LTq ligaments sectioning, wrist loading forced the triquetrum into flexion (5.4° average) and supination (2.9 ). The only muscle capable of extending and pronating the collapsed triquetrum was the extensor carpi ulnaris (ECU).

CONCLUSIONS

Inadequate ECU muscle function is an important destabilizing factor in LTq deficient wrists. Dynamic LTq instabilities may benefit from proprioceptionally training the ECU muscle, while avoiding carpal supination torques.

Subluxation of the extensor carpi ulnaris tendon associated with the extensor digitorum tendon subluxation of the long finger

A twenty-year-old male visited our clinic with wrist and long finger metacarpophalangeal (MP) joint pain. Dynamic ultrasonography revealed sagittal band (SB) ulnar subluxation and extensor carpi ulnaris (ECU) volar subluxation. Magnetic resonance imaging showed longitudinal splitting and dislocation of the volar half slip of the ECU tendon. The redundant radial SB was augmented and ECU sheath was advanced to the periosteum using suture anchors. He was able to perform his previous activities at the last follow-up. We encountered a case of "simulateous" ECU dislocation with extensor tendon subluxation of the long finger at the MP joint. Therefore, we report this case with a review of the relevant literature.