Extensor Carpi Ulnaris Tendon Research Articles

Revision of Failed Nonanatomic Extensor Retinacular Stabilization of the Unstable ECU Tendon: Surgical Technique and Case Series.

Nonanatomic surgical stabilization of the unstable extensor carpi ulnaris (ECU) tendon (where the subluxing tendon is re-routed away from the bony groove in the distal ulna) utilizes a flap of extensor retinaculum to create a new retaining sheath that will stabilize the tendon during forearm rotation movements. When this surgery fails, the extensor retinaculum tissue does not regenerate with sufficient structural strength to be used again. Previously, a different approach has then been needed for revision surgery, often using more complex surgical techniques with a substantially greater impact on recovery. We describe a highly reliable yet simple method of using local soft tissue to adequately restabilize the subluxing ECU tendon in cases where an extensor retinacular flap has already been used. We report the results of this technique in 4 patients, all of whom returned to jobs/hobbies where ECU instability was a considerable functional risk.

Effects of distal ulnar morphology on symptomatic extensor carpi ulnaris (ECU) subluxation and the clinical outcomes of anatomic ECU subsheath reconstruction: a retrospective observational study

Purpose: This study aimed to evaluate the association between distal ulnar morphology and symptomatic extensor carpi ulnaris (ECU) subluxation and assess the results of anatomic ECU subsheath reconstruction.Methods: To investigate the effects of distal ulnar morphology on symptomatic ECU subluxation, we compared distal ulnar morphology using magnetic resonance imaging among three groups: group 1 (symptomatic ECU subluxation, 12 cases), group 2 (non-symptomatic ECU subluxation, 24 cases), and group 3 (no ECU subluxation, 24 cases). Distal ulnar morphology was evaluated using ulnar variance, ulnar styloid length, and ECU groove depth. Clinical outcomes were evaluated using the Patient-Related Wrist Evaluation (PRWE) score, the Disabilities of the Arm, Shoulder, Hand (DASH) score, grip strength, and the range of motion of the wrist joint.Results: Ulnar variance showed a statistically significant difference between groups 1 and 2, and ECU groove depth showed statistically significant differences between groups 1 and 2 and between groups 2 and 3. Ulnar styloid length showed no statistically significant between-group differences. In patients with symptomatic ECU subluxation, there was a significant increase in the range of motion in supination and grip strength, and a significant decrease in the DASH score (from 40 to 9) and PRWE score (from 48 to 12). Conclusion: Negative ulnar variance was associated with symptomatic ECU subluxation, and shallow ECU groove depth was correlated to asymptomatic ECU subluxation, but unrelated to symptoms. Anatomic ECU tendon sheath reconstruction was identified as an effective surgical method.

Anconeus Muscle Transfer to Correct or Prevent Wrist Radial Deviation in Radial and Posterior Interosseous Nerve Injuries

Wrist radial deviation is a possible complication of tendon transfer for restoration of wrist extension in cases of radial nerve paralysis. In posterior interosseous nerve (PIN) injury, this is because of the imbalance caused by the intact extensor carpi radialis longus and paralysis of the extensor carpi ulnaris (ECU). This deformity may also occur following transfer of the pronator teres (PT) to the extensor carpi radialis brevis (ECRB) for radial nerve palsy. To address wrist radial deviation, we propose transferring the anconeus muscle, extended by the intermuscular septum between the ECU and the flexor carpi ulnaris (FCU), to the ECU tendon. Through an incision over the ulna, the intermuscular septum between the ECU and FCU is harvested at the level of the periosteum and left attached to the anconeus proximally. The anconeus muscle is then released from the ulna, and the intramuscular septum extension is sutured to the ECU tendon under maximal tension. Anconeus muscle transfer was performed on two patients to correct chronic wrist radial deviation following PT to ECRB tendon transfer for radial nerve injury, as well as on two patients with PIN paralysis. In four patients, transfer was performed in addition to standard tendon transfers for radial nerve paralysis to prevent radial wrist deviation deformity. Wrist radial deviation was corrected or prevented in all but one patient at an average follow-up of 10 months. Patients with PIN lesions and those who had anconeus transfer concomitantly with radial nerve tendon transfers were capable of active ulnar deviation. No patient experienced elbow extension weakness, pain, or instability. Anconeus muscle transfer extended by intermuscular septum presents a viable alternative for addressing radial deviation of the wrist in cases of PIN nerve lesions or following PT to ECRB tendon transfer in radial nerve paralysis. Therapeutic V.

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

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

The Effect of Arthroscopic Triangular Fibrocartilage Repair on Accompanying Extensor Carpi Ulnaris Tendinitis and Synovitis in Triangular Fibrocartilage Tears.

Purpose Management of ulnar-sided wrist pain is difficult due to the complexity of the anatomy and the similarity of the signs and symptoms of possible diagnoses. The study's main purpose is to examine the effect of arthroscopic triangular fibrocartilage (TFC) repair on untreated extensor carpi ulnaris (ECU) tendinitis and synovitis. Methods Thirteen patients who underwent arthroscopic TFC repair in our clinic and preoperatively demonstrated ECU tendon pathology with magnetic resonance imaging (MRI) were included in the retrospective study. Pre- and postoperative visual analog scale (VAS), pre- and postoperative tendinitis and synovitis, postoperative Mayo and patient-rated wrist evaluation score, postoperative grip strength of the operated and control sides, short and long diameters of the ECU tendon in ultrasonography were recorded. Results The mean age of 13 patients (9 females and 4 males) was 39.54 ± 13.54, and the mean follow-up period was 26 ± 7.25 months. While there was no significant difference between pre- and postoperative tendinitis or synovitis levels, VAS decreased significantly (8.46 ± 1.33 vs. 3.00 ± 2.31, p = 0.0016). While the grip strength was 21.78 ± 7.83 on the control side, it was 18.28 ± 7.51 on the surgery side, being significantly lower ( p = 0.0252). Ulnar variance did not affect tendinitis or synovitis. Short and long diameters of ECU were similar for the operated and control sides. While the short diameter did not affect the synovitis-tendinitis score, the bigger the long diameter, the higher the synovitis score (rho = 0.5162). Conclusion In the presence of ECU, tendon pathologies accompanying TFC lesions, additional surgical interventions are mandatory as arthroscopic TFC repair has no significant effect on the healing of ECU. Level of evidence : 4.

Subcutaneous Dorsomedial Triangle of Forearm: Surgical Anatomy and Clinical Implication.

Background The purpose of the study was to provide a practical landmark for localizing the dorsal branch of the ulnar artery and nerve, to approach for microsurgical flaps, for harvesting nerve grafts and also to avoid these nerves during insertion of wrist arthroscopy portals. Material and methods Forty adult cadaveric upper limbs (20 right and 20 left) were dissected for localizing the dorsal branches of the ulnar artery and nerve. The ramification patterns of the nerve were mapped. The wrist arthroscopy portals are located radial and ulnar to the tendon of extensor carpi ulnaris at the level of the wrist joint, and their designated names are '6R & 6U', respectively. The distance of branches of the nerve from the 6U and 6R portals for wrist arthroscopy was recorded. Results The present study has delineated asubcutaneous dorsomedial triangular area in the distal forearm. The construction of this triangle uses palpable landmarks, i.e. pisiform bone, styloid process and subcutaneous border of the ulna. The measure of the sides of the triangle uses proportion rather than absolute measurements and hence is person specific. The dorsal branches of the ulnar nerve and artery are consistently given off in the triangle's upper third and middle third, respectively. Four branching patterns have been mapped, with one dominant pattern in 67.5% of limbs. In three-fourths of cases, one branch of the dorsal branch of the ulnar nerve consistently overlies the 6U portal and hence runs a higher risk of injury. Conclusion The study suggests more practical, accurate, reliable and consistent surface landmarks for the localization of the dorsal branch of the ulnar artery and nerve for reconstructive microsurgery for distal hand defects.

A Novel Technique Using the Dorsal Capsule of the Distal Radioulnar Joint for Extensor Carpi Ulnaris Tendon Subsheath Reconstruction.

Background Ulnar-sided wrist pain is a common problem encountered by hand surgeons. Symptomatic recurrent subluxation of the extensor carpi ulnaris (ECU) tendon has become increasingly recognized as one of the pathological conditions leading to ulnar-sided wrist pain. Surgical reconstruction of the subsheath is usually needed. ECU tendon subsheath reconstruction with the periosteal flap was first described by Schlesinger in 1907. Since then, various other techniques have been widely used. We describe a technique of ECU subsheath reconstruction using the dorsal capsule of the distal radioulnar joint (DRUJ). Description of Technique Two hand surgeons performed the surgeries with the same steps taken each time. A detailed description of our surgical technique, with the dorsal capsule of the DRUJ used to reconstruct the ECU tendon subsheath, is illustrated. Patient and Methods Patients who presented with symptomatic ECU instability despite conservative treatment or who have failed primary subsheath repair were offered this surgical option. Patients were followed up postoperatively for an average duration of 6.7 months in our outpatient clinics for assessment of wrist function. The surgical outcomes were reviewed and graded with the Modified Mayo Wrist Score (MMWS). Results All but one of the seven patients had an overall improvement in their range of movement of the wrist, grip strength, and pain scores. Four patients had excellent outcomes on the MMWS, one of whom had an asymptomatic recurrence seen on dynamic ultrasound. Two patients required subsequent surgeries: one had an excellent outcome and the other had a poor outcome on the MMWS. Conclusion We present our first seven cases of ECU subsheath reconstruction with the dorsal capsule of the DRUJ. Our results in the short term have been satisfactory. The technique does not disrupt the integrity of the extensor retinaculum, which is essential for optimal extensor tendon function, and can also be considered as an option to salvage failed procedures.

Extensor Carpi Ulnaris Instability: A Comprehensive Review of Pathology and Operative Techniques.

The extensor carpi ulnaris (ECU) is primarily responsible for extension and ulnar deviation at the wrist. Secondary to repetitive loading of, or acute trauma to the flexed, supinated and ulnarly deviated wrist, the ECU tendon can be a common source of ulnar-sided wrist pain. Common pathology includes ECU tendinopathy, tenosynovitis, tendon instability, and tendon rupture. Extensor carpi ulnaris pathology commonly occurs in athletes and patients with inflammatory arthritis. Given the multitude of available methods to treat ECU tendon pathology, the aim of our study was to outline operative management of ECU tendon pathology, with emphasis on reviewing techniques for addressing ECU instability. We acknowledge a continuing debate between anatomical and nonanatomical techniques for ECU subsheath reconstruction. However, use of a portion of the extensor retinaculum for nonanatomical reconstruction is commonly used and demonstrates successful outcomes. Future comparative studies on ECU fixation are required to increase data on patient outcomes, to further define and standardize these techniques.

Motion Analysis of the Extensor Carpi Ulnaris in Triangular Fibrocartilage Complex Injury Using Ultrasonography Images.

The subsheath of the extensor carpi ulnaris (ECU) tendon, a component of the triangular fibrocartilage complex (TFCC), is particularly important as it dynamically stabilizes the distal radioulnar joint. However, the relationship between TFCC injury and ECU dynamics remains unclear. This study aimed to analyze ECU movement and morphology using ultrasonography (US) images. Twenty wrists of patients with TFCC injury, who underwent TFCC repair, were included in the injury group, and 20 wrists of healthy volunteers were in the control group. For static image analysis, curvature and linearity ratios of the ECU in US long-axis images captured during radioulnar deviation were analyzed. For dynamic analysis of the ECU, the wrist was moved from radial deviation to ulnar deviation at a constant speed, and the velocity of the tendon was analyzed using particle image velocimetry. The static analysis showed that the ECU tendon was more curved in ulnar deviation in the injury group than in the control group, and the dynamic analysis showed that only vertical velocity toward the deep side during ulnar deviation was higher in the injury group. These results suggest that TFCC injury caused ECU curvature during ulnar deviation and increased the vertical velocity of the ECU during wrist deviation.

Operative Approaches to the distal radioulnar Joint and distal Ulna

At the distal radioulnar joint (DRUJ) and the ulnocarpal joint several anatomical structures are in a limited space. Therefore, the operative approach has to consider the pathology to be treated. The DRUJ may be approached from the dorsal or the palmar side. Procedures to treat the arthrotically destroyed DRUJ involving bone resection of the ulnar head and destabilizing ligamentous injuries of the triangular fibrocartilage complex (TFCC) are best approached from the dorsal side. This approach allows excellent visualization of the ulnar head and the ulnar and radial attachment of the TFCC. The arthroscopic, half open refixation of the ulnar avulsion of the TFCC may be performed using a variety of limited and small approaches over the dorsal or lateral ulnar head. Pathologies with an origin at the palmar aspect of the DRUJ as the palmar dislocation of the ulnar head in the DRUJ or the shrinkage and scaring of the palmar capsule with consecutive pronation contracture require a palmar approach. Reduction and osteosynthesis of fractures in the area of the ulnar head are preformed using a lateral approach along the styloid process and the ulnar head between the flexor and the extensor carpi ulnaris tendons. Along the ulnar shaft elective ulnar shortening osteotomy as well as fracture reduction and osteosynthesis are best performed from an ulno palmar approach.

An Analysis of Extensor Carpi Ulnaris Groove Morphology and Tendon Instability.

The extensor carpi ulnaris (ECU) tendon has a distinct subsheath at the distal ulna. Symptomatic tears of this subsheath and subluxation of the ECU tendon often require reconstruction. We sought to determine the anatomical constraints of the ECU subsheath. The ECU subsheath was exposed on 12 fresh-frozen upper extremities. The tip of the ulnar styloid, the distal ulnar joint surface, and the proximal extent of the distal radio-ulnar joint were identified and dimensions measured. Subluxation of the tendon was then assessed with and without an intact subsheath in 9 specimens. The travel of the tendon was measured in pronation through supination and flexion before and after sectioning of the subsheath. The ECU subsheath is 8.9 mm (standard deviation [SD] = 0.8 mm) wide proximally and 9.0 mm (SD = 1.2 mm) distally. The distal ulnar insertion is 0.5 mm (SD = 0.8 mm) proximal to the tip of the styloid, and stretches 10.2 mm (SD = 2.7 mm) proximally. From maximum pronation to maximum supination and flexion, the ECU tendon traveled 3.32 mm (SD = 4.24) medially when the subsheath was intact and 5.42 mm (SD = 5.0 mm) after sectioning. The maximum depth of the ulnar groove was 2.5 mm (1.59-3.56 mm). There was no significant association between changes in ECU subluxation and the depth of the ECU groove (Spearman's rho = 0.25). The ECU subsheath is roughly 1 cm square stretching proximally from the ulnar styloid. ECU groove depth is not a significant independent predictor of tendon subluxation.

The triangular fibrocartilage complex in the human wrist: A scoping review toward uniform and clinically relevant terminology.

The aim of this scoping review was to assess the composition, terminology, and anatomy of the triangular fibrocartilage complex (TFCC) of the wrist and propose unambiguous terminology regarding the individual components. The review was conducted according to the methodological framework by Arksey and O'Malley (International Journal of Social Research Methodology, 2005, 8, 19–32). Electronic databases were searched from inception until September 1, 2021 for original anatomical studies, using MeSH terms and keywords on terminology and anatomy of TFCC components. Studies using gross dissections or macro‐ or microscopic histology were included. Animal studies, fetal studies and studies with unknown disease status, were excluded. A total of 24 studies were included. The articular disc, the radioulnar ligaments, the meniscus homologue and the extensor carpi ulnaris tendon (sub)sheath were unanimously classified as TFCC components. One study did not include the ulnolunate and ulnotriquetral ligaments and only one study did include the ligamentum subcruentum. The largest disagreement existed regarding the inclusion of the ulnar collateral ligament. Terminological ambiguity was seen in “triangular fibrocartilage,” “triangular ligament,” “igamentum subcruentum,” and the “proximal and distal lamina.” Anatomical ambiguity existed especially regarding the radioulnar ligaments, the ulnar attachments of the TFCC and the ulnar collateral ligament. Definitions of the individual TFCC components are redundant, ambiguous, and ill‐defined and therefore subject to different interpretations. In order to preclude confusion, consensus regarding terminology is recommended. We proposed a concise definition of the healthy TFCC that can be used as a starting point for future studies and current clinical practice.

Arthroscopic Triangular Fibrocartilage Complex Reconstruction Using a Palmaris Longus Tendon Graft.

Patients suffer from persistent ulnar wrist pain and distal radioulnar joint instability because of chronic triangular fibrocartilage complex (TFCC) foveal tear are treated with TFCC reconstruction. We performed an arthroscopic TFCC reconstruction using a palmaris longus tendon graft that provided a minimally invasive procedure. After confirming the TFCC foveal tear and stability between the TFCC remnant and radius, the bone tunnel was made in the ulna from the ulnar shaft to ulnar fovea. The position of the bone tunnel was checked by fluorography and arthroscopy. Curved bendable 18-gauge needles into which 3-0 nylon sutures were inserted in a loop shape were passed through the tunnel from the ulnar side, and both volar-side and dorsal-side TFCC remnants were penetrated. The nylon suture was extracted from the arthroscopic 4/5 portal, and the palmaris longus tendon graft was introduced into the joint. The graft was passed through the TFCC remnant and ulnar bone tunnel from the arthroscopic portal and fixed to the ulna using an interference screw. This procedure was indicated for TFCC foveal tears with intact radial-side TFCC remnants. If the radial-side tear and instability between the TFCC and radius coexist, this technique is contraindicated, and stabilization of both the radial and ulnar sides of the TFCC should be considered. This arthroscopic technique does not violate the distal radioulnar joint capsule, extensor carpi ulnaris tendon, or tendon sheath. In addition, it helps to stabilize the ulnar carpal complex.

Very low prevalence of ultrasound-detected tenosynovial abnormalities in healthy subjects throughout the age range: OMERACT ultrasound minimal disease study

ObjectivesThis study aimed to determine the prevalence of ultrasound-detected tendon abnormalities in healthy subjects (HS) across the age range.MethodsAdult HS (age 18–80 years) were recruited in 23 international Outcome Measures...

The clinical significance of magnetic resonance imaging of the hand: an analysis of 318 hand and wrist images referred by hand surgeons

Magnetic resonance imaging (MRI) is a common diagnostic tool in hand surgery. However, there is limited knowledge on the kind of findings that are relevant in treatment planning. We analysed the findings and utility of arm, wrist, metacarpal, and finger MRIs taken in a tertiary hand surgery clinic of 318 consecutive images from 316 patients referred by a hand surgeon or hand surgeon resident. Ganglions (28%), findings on the extensor carpi ulnaris tendon (18%) and on the triangular fibrocartilage (18%) were the most common findings and increased with patient age; the clinical significance of these findings was minimal. The correlation between the clinical scaphoid shift test or the fovea sign test and MRI was also non-significant. Despite findings on MRI, the diagnosis remained unsolved in 76 (24%) cases. However, MRI had a role in reassuring the patient, and in 70% of the cases, further follow-up was unnecessary. This study demonstrates that the indications for wrist and hand MRI must be considered thoroughly and interpretation of the MRI report requires knowledge.

Wrist injuries detected on magnetic resonance imaging in athletes participating in the Rio de Janeiro 2016 Summer Olympic Games.

Traumatic and chronic overuse injuries of the wrist are common in athletes. The purpose of this study was to describe the frequency, anatomic distribution, and severity of MRI-detected wrist joint injuries amongst athletes who competed in the Rio de Janeiro 2016 Summer Olympics. All sports injuries reported by the National Olympic Committee medical teams and the Organizing Committee medical staff during the 2016 Summer Olympics were analyzed. MRI was performed at the International Olympic Committee's polyclinic within the Olympic Village, using 3T and 1.5T scanners. The MRIs were interpreted by musculoskeletal radiologists with expertise in sports injuries. The distribution of wrist injuries by anatomic location and sports discipline and the severity of injuries were recorded. A total of 1,101 injuries were reported in the 11,274 athletes. Twenty-five athletes (72% male, median-age =27 years) had an MRI for wrist injuries. Fifty-six percent (N=14) of these athletes had triangular fibrocartilage pathology, 64% of which were chronic, while 36% were acute. There were scapholunate ligament injuries in 40% of the athletes. The extensor carpi ulnaris tendon was most commonly injured tendon. Fractures were seen in 32% of the athletes (N=8) and most commonly involved the scaphoid. Athletes participating in weightlifting (N=4, 16%), tennis (N=3, 12%) and gymnastics (N=3, 12%) athletes were most commonly affected. MRI-detected wrist injuries during the 2016 Summer Olympics most commonly affected the scapholunate ligament, extensor carpi ulnaris tendon and triangular fibrocartilage articular disc. The highest occurrence of wrist injuries was in weightlifting, tennis and gymnastics.

Is it really safe to evaluate symptomatic extensor carpi ulnaris tendon instability by magnetic resonance imaging (MRI)?

The extensor carpi ulnaris (ECU) tendon is in the sixth extensor compartment of the wrist and is isolated from other tendons by a different sheath. Extensor carpi ulnaris pathologies are characterized by pain locally localized to the wrist ulnar side. Outpatient records and wrist MRI (magnetic resonance imaging) tests were retrospectively scanned between January 2018 and July 2019. By examining the anamnesis and examination notes of the patients in the outpatient clinic records, patients with wrist ulnar side pain, pain or sensitivity on the ulnar styloid and provocation test (synergy) were assigned to the first study group (Group 1).The second study group was composed of patients who underwent wrist MR for the diagnosis or differential diagnosis of a synovial cyst around the wrist, without ulnar side pain (Group 2).While evaluating MR images in the axial plane, the depth and width of the ulnar groove, thickness of the ECU tendon were measured. The position of the ECU tendon relative to the ulnar groove and the forearm rotation during the shooting were recorded.105 cases evaluated, there were 41 cases in the symptomatic subgroup and 64 cases in the asymptomatic subgroup. Among all patients, the mean patient age was 38.05.In the evaluation according to whether cases were symptomatic or not, there was no significant relationship between being symptomatic and the degree of instability and MR withdrawal position. Our study suggests that ECU instability in MR is not a specific condition, and detection of MR in instability may not be associated with a patient's symptoms.

Ulnar-Sided Wrist Pain in the Athlete: Sport-Specific Demands, Clinical Presentation, and Management Options.

Ulnar-sided wrist injuries are common in sports that require repeated pronosupination, wrist radial/ulnar deviation, axial loading, and gripping equipment. Common anatomic structures affected include the triangular fibrocartilage complex, extensor carpi ulnaris tendon, distal radioulnar and ulnocarpal joints, and hamate bone. Presenting symptoms include pain with activity, swelling, possible snapping or clicking, and reproduction of symptoms with provocative maneuvers. Imaging may confirm or rule out pathologies, but abnormal findings also may present in asymptomatic athletes. Initial treatment is usually nonoperative with splinting, load management, activity modification, strengthening the components of the kinetic chain of the particular sport, and pain management. Surgery is usually indicated in ulnar-wrist pain pathology such as hook of hamate fractures and required in associated instability. Future research should address specific treatment and rehabilitation protocols, emphasizing the complete kinetic chain along with the injured wrist.

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

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. 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). 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. 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. 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.

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. 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. 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). 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.