Ultrasound assessment of the rotator cuff cable: comparison between young and elderly asymptomatic volunteers and interobserver reproducibility

Rotator cable and rotator interval: anatomy, biomechanics and clinical importance

The rotator cable and rotator interval are among the most recent topics of interest in current shoulder literature. Most of the research has been published in the last two decades and our understanding about the importance of these anatomical structures has improved with biomechanical studies, which changed the pre- and intra-operative approaches of shoulder surgeons to rotator cuff tears in symptomatic patients.

The rotator cable is a thick fibrous bundle that carries the applied forces to the rotator cuff like a ‘suspension bridge’. Tears including this weight-bearing bridge result in more symptoms. On the other hand, the rotator interval is more like a protective cover consisting of multiple layers of ligaments and the capsule rather than a single anatomical formation like the rotator cable.

Advances in our knowledge about the rotator interval demonstrate that even basic anatomical structures often have greater importance than we may have understood. Misdiagnosis of these two important structures may lead to persistent symptoms.

Furthermore, some distinct rotator cuff tear patterns can be associated with concomitant rotator interval injuries because of the anatomical proximity of these two anatomical regions. We summarize these two important structures from the aspect of anatomy, biomechanics, radiology and clinical importance in a review of the literature.

Cite this article: EFORT Open Rev 2019;4:56-62. DOI: 10.1302/2058-5241.4.170071.

Rotator cable in pathological shoulders: comparison with normal anatomy in a cadaveric study

The rotator cable is a semicircular thickening of the glenohumeral joint capsule. It travels between tubercles of the humerus and interweaves with the supra- and infraspinatus muscle tendons. The rotator cable anchors these tendons to the tubercles, playing the role of a suspension bridge. However, little is known about the modifications of this cable that result from pathologies to the rotator cuff tendons. Thus, we aim to compare the morphology of the normal rotator cable with cables in specimens with rotator cuff injuries. The glenohumeral joint was dissected in 30 cadaveric shoulders. The supra-, infraspinatus and teres minor muscles were inspected for injuries and the rotator cable was visualised. The cables course was determined and the width, length and thickness were measured. The rotator cable was found present in all cadavers dissected. In three specimens there was a partial injury of the supraspinatus tendon (two from capsular side and one from bursal side). The rotator cable was thickened in the cases of capsular tears. In another two specimens the supraspinatus and infraspinatus muscles were torn completely and in these cases the rotator cable was blended with retracted stumps and elongated to the level of the glenoid rim. The rotator cable creates a functional complex with the supra- and infrasinatus muscles. The morphology of the cable differs in cases of rotator cuff injury.

Rotator cuff calcific tendinopathy: from diagnosis to treatment

Rotator cuff calcific tendinopathy (RCCT) is a very common condition caused by the presence of calcific deposits in the rotator cuff (RC) or in the subacromial-subdeltoid (SASD) bursa when calcification spreads around the tendons. The pathogenetic mechanism of RCCT is still unclear. It seems to be related to cell-mediated disease in which metaplastic transformation of tenocytes into chondrocytes induces calcification inside the tendon of the RC. RCCT is a frequent finding in the RC that may cause significant shoulder pain and disability. It can be easily diagnosed with imaging studies as conventional radiography (CR) or ultrasound (US). Conservative management of RCCT usually involves rest, physical therapy, and oral NSAIDs administration. Imaging-guided treatments are currently considered minimally-invasive, yet effective methods to treat RCCT with about 80% success rate. Surgery remains the most invasive treatment option in chronic cases that fail to improve with other less invasive approaches. (www.actabiomedica.it)

Rotator Cuff Calcific Tendinopathy: Randomized Comparison of US-guided Percutaneous Treatments by Using One or Two Needles

Purpose To determine whether the use of one or two needles influences procedure performance and patient outcomes for ultrasonography (US)-guided percutaneous irrigation of calcific tendinopathy. Materials and Methods Institutional review board approval and written informed patient consent were obtained. From February 2012 to December 2014, 211 patients (77 men and 134 women; mean age, 41.6 years ± 11.6; range, 24-69 years) with painful calcific tendinopathy diagnosed at US were prospectively enrolled and randomized. Operators subjectively graded calcifications as hard, soft, or fluid according to their appearance at US. US-guided percutaneous irrigation of calcific tendinopathy (local anesthesia, needle lavage, intrabursal steroid injection) was performed in 100 patients by using the single-needle procedure and in 111 patients by using the double-needle procedure. Calcium dissolution was subjectively scored (easy = 1; intermediate = 2; difficult = 3). Procedure duration was recorded. Clinical evaluation was performed by using the Constant score up to 1 year after the procedure. The occurrence of postprocedural bursitis was recorded. Mann-Whitney U, χ², and analysis of variance statistics were used. Results No difference in procedure duration was seen overall (P = .060). Procedure duration was shorter with the double-needle procedure in hard calcifications (P < .001) and with the single-needle procedure in fluid calcifications (P = .024). Ease of calcium dissolution was not different between single- and double-needle procedures, both overall and when considering calcification appearance (P > .089). No clinical differences were found (Constant scores for single-needle group: baseline, 55 ± 7; 1 month, 69 ± 7; 3 month, 90 ± 5; 1 year, 92 ± 4; double-needle group: 57 ± 6; 71 ± 9; 89 ± 7; 92 ± 4, respectively; P = .241). In the single-needle group, nine of 100 cases (9%) of postprocedural bursitis were seen, whereas four of 111 cases (3.6%) were seen in the double-needle group (P = .180). Conclusion The only difference between using the single- or double-needle procedure when performing US-guided percutaneous irrigation of calcific tendinopathy is procedure duration in hard and fluid calcifications. Clinical outcomes are similar up to 1 year. ^© RSNA, 2017.

Reporting rotator cuff tears on magnetic resonance arthrography using the Snyder's arthroscopic classification

AIM

To determine diagnostic performance of magnetic resonance arthrography (MRA) in evaluating rotator cuff tears (RCTs) using Snyder's classification for reporting.

METHODS

One hundred and twenty-six patients (64 males, 62 females; median age 55 years) underwent shoulder MRA and arthroscopy, which represented our reference standard. Surgical arthroscopic reports were reviewed and the reported Snyder's classification was recorded. MRA examinations were evaluated by two independent radiologists (14 and 5 years' experience) using Snyder's classification system, blinded to arthroscopy. Agreement between arthroscopy and MRA on partial- and full-thickness tears was calculated, first regardless of their extent. Then, analysis took into account also the extent of the tear. Interobserver agreement was also calculated the quadratically-weighted Cohen kappa statistics.

RESULTS

On arthroscopy, 71/126 patients (56%) had a full-thickness RCT. The remaining 55/126 patients (44%) had a partial-thickness RCT. Regardless of tear extent, out of 71 patients with arthroscopically-confirmed full-thickness RCTs, 66 (93%) were correctly scored by both readers. All 55 patients with arthroscopic diagnosis of partial-thickness RCT were correctly assigned as having a partial-thickness RCT at MRA by both readers. Interobserver reproducibility analysis showed total agreement between the two readers in distinguishing partial-thickness from full-thickness RCTs, regardless of tear extent (k = 1.000). With regard to tear extent, in patients in whom a complete tear was correctly diagnosed, correct tear extent was detected in 61/66 cases (92%); in the remaining 5/66 cases (8%), tear extent was underestimated. Agreement was k = 0.955. Interobserver agreement was total (k = 1.000).

CONCLUSION

MRA shows high diagnostic accuracy and reproducibility in evaluating RCTs using the Snyder's classification for reporting. Snyder's classification may be adopted for routine reporting of MRA.

A systematic review of the reliability of diagnostic ultrasound imaging in measuring tendon size: Is the error clinically acceptable?

BACKGROUND

Diagnostic ultrasound (US) is a commonly used imaging modality for visualising tendon pathology and morphology. In comparison to magnetic resonance imaging (MRI), diagnostic US is perceived to have a higher risk of error when evaluating tendon size.

AIM

To systematically assess the evidence regarding the Intra rater and Inter rater reliability of diagnostic US measurements of tendon size.

DATA SOURCES

Eight electronic databases were searched using an agreed set of keywords. Studies which investigated the reliability of tendon size (thickness or cross sectional area) using diagnostic US were eligible.

RESULTS

Combined Inter rater and Intra rater ICC values for tendon thickness ranged from 0.45 to 0.99. Combined Inter rater and Intra rater ICC values for tendon cross-sectional area (CSA) ranged from 0.58 to 0.92. Overall, Intra rater ICC values (0.59-0.99) were marginally higher than Inter rater values (0.45-0.99) across all tendon sites. Percentage co-efficient of variation (CV%) for tendon thickness and CSA ranged from 0 to 35% across all tendons. Percentage standard error of the mean SEM% values for tendon thickness ranged from 3.33% to 7.39%.

CONCLUSIONS

The findings of this review suggest diagnostic US measures of tendon size are reliable, both in terms of relative and absolute reliability. However, the findings must be considered in light of the presence of tendon abnormalities in a large percentage of asymptomatic populations.

Sonographic Visualization of the Rotator Cable in Patients With Symptomatic Full-Thickness Rotator Cuff Tears: Correlation With Tear Size, Muscular Fatty Infiltration and Atrophy, and Functional Outcome

OBJECTIVES

To assess the prevalence of sonographic visualization of the rotator cable in patients with symptomatic full-thickness rotator cuff tears and asymptomatic controls and to correlate rotator cable visualization with tear size, muscular fatty infiltration and atrophy, and the functional outcome in the patients with rotator cuff tears.

METHODS

Fifty-seven patients with rotator cuff tears and 30 asymptomatic volunteers underwent shoulder sonography for prospective assessment of the rotator cable and rotator cuff tear and responded to 2 functional outcome questionnaires (shortened Disabilities of the Arm, Shoulder, and Hand [QuickDASH] and Constant). In the patients with rotator cuff tears, appropriate tests were used to correlate rotator cable visualization with the tear size, functional outcome, muscular fatty infiltration, and atrophy.

RESULTS

The patients with rotator cuff tears included 25 women and 32 men (mean age,57 years; range, 39-67 years), and the volunteers included 13 women and 17 men (mean age, 56 years; range, 35-64 years). The rotator cable was identified in 77% (23 of 30) of controls and 23% (13 of 57) of patients with rotator cuff tears. In the patients, nonvisualization of the rotator cable correlated with larger tears (P < 0.001) and higher grades of supraspinatus atrophy (P = .049) and fatty infiltration (P = .022). There was no significant correlation with functional outcome scores (QuickDASH, P = .989; Constant, P = .073) or infraspinatus fatty infiltration (P = .065).

CONCLUSIONS

Nonvisualization of the rotator cable was more prevalent in patients with symptomatic rotator cuff tears than asymptomatic controls and was associated with a larger tear size and greater supraspinatus fatty infiltration and atrophy. Diligent assessment of the supraspinatus muscle should be done in patients with rotator cuff tears without a visible rotator cable, as the integrity of these anatomic structures may be interdependent.

Dynamic high-resolution ultrasound of the shoulder: how we do it

Ultrasonography (US) is an established and well-accepted modality that can be used to evaluate articular and peri-articular structures around the shoulder. US has been proven to be useful in a wide range of rotator cuff diseases (tendon tears, tendinosis, and bursitis) as well as non-rotator cuff abnormalities (instability problems, synovial joint diseases, and nerve entrapment syndromes). Diagnostic accuracy of shoulder US when evaluating rotator cuff tears can reach 91-100% for partial and full thickness tears detection, respectively, having been reported to be as accurate as magnetic resonance imaging in experienced hands. US is cheap, readily available, capable to provide high-resolution images, and does not use ionizing radiations. In addition, US is the only imaging modality that allows performing dynamic evaluation of musculoskeletal structures, that may help to further increase diagnostic performance. In this setting, a standardized imaging protocol is essential for an exhaustive and efficient examination, also helping reducing the intrinsic dependence from operators of US. Furthermore, knowledge of pitfalls that can be encountered when examining the shoulder may help to avoid erroneous images interpretation. In this article we use detailed anatomic schemes and high-resolution US images to describe the normal US anatomy of soft tissues, articular, and para-articular structures located in and around the shoulder. Short video clips emphasizing the crucial role of dynamic maneuvers and dynamic real-time US examination of these structures are included as supplementary material.

Assessment of the rotator cable in various rotator cuff conditions using indirect MR arthrography

BACKGROUND

The rotator cable is an important structure providing stress shield to the rotator cuff, similar to the mechanism of suspension bridge.

PURPOSE

To evaluate the visibility and appearance of the rotator cable in various conditions of the rotator cuff, using indirect magnetic resonance (MR) arthrography.

MATERIAL AND METHODS

Indirect MR arthrography images from 27 patients (age range, 20-63 years) with normal rotator cuffs, and 47 (age range, 20-73 years) with tendinosis, 32 (age range, 49-71 years) with partial-thickness tears, and 55 (age range, 44-75 years) with full-thickness tears in the supraspinatus and infraspinatus tendons (SST-ISTs) were included in this study. In these various rotator cuff conditions, the visibility and appearance (thickness and width) of the rotator cable and the relationships between the rotator cable appearance, rotator cuff tear size, rotator cuff thickness, and patient's age were assessed.

RESULTS

On the sagittal MR images, all rotator cables were visible in the normal rotator cuffs and tendinosis/partial-thickness tears of SST-ISTs. In the order of normal cuff, tendinosis, partial-thickness tear, and full-thickness tear of SST-ISTs, the rotator cable tended to become thicker (1.07, 1.27, 1.32, and 1.59 mm, respectively) and narrower (12.1, 10.68, 10.90, and 8.55 mm, respectively). The thickness of the rotator cable was significantly positively correlated with the rotator cuff thickness in the normal rotator cuffs (coefficient, 0.49; P = 0.010) and tendinosis of SST-ISTs (coefficient, 0.53; P < 0.001), but was not correlated with patients' age.

CONCLUSION

On sagittal plane of indirect MR arthrography, most rotator cables were visible. The appearance of the rotator cable changed according to the rotator cuff condition.

Assessment of rotator cuff repair integrity using ultrasound and magnetic resonance imaging in a multicenter study

BACKGROUND

This study compared ultrasound and magnetic resonance imaging (MRI) evaluation of the repaired rotator cuff to determine concordance between these imaging studies.

METHODS

We performed a concordance study using the data from a prospective nonrandomized multicenter study at 13 centers. A suture bridge technique was used to repair 113 rotator cuff tears that were between 1 and 4 cm wide. Repairs were evaluated with MRI and ultrasound at multiple time points after surgery. The MRI scans were read by a central radiologist and the surgeon, and the ultrasounds were read by a local radiologist or the surgeon who performed the ultrasound.

RESULTS

The concordance between the central radiologist's MRI reading and the investigator's MRI readings at all time points was 89%, with a κ coefficient of 0.60. The concordance between the central radiologist's MRI and ultrasound readings at all time points was 85%, with a κ coefficient of 0.40. The concordance between the investigator's MRI and ultrasound readings was 92%, with a κ coefficient of 0.70.

CONCLUSIONS

In the community setting, ultrasound may be used to evaluate the integrity of a repaired rotator cuff tendon and constitutes a comparable alternative to MRI when evaluating the integrity of a rotator cuff repair. Clinical investigators should compare their postoperative ultrasound results with their postoperative MRI results for a certain time period to establish the accuracy of ultrasound before relying solely on ultrasound imaging to evaluate the integrity of their rotator cuff repairs.

High-resolution ultrasound of rotator cuff and biceps reflection pulley in non-elite junior tennis players: anatomical study

Background

Tennis is believed to be potentially harmful for the shoulder, therefore the purpose of this study is to evaluate the anatomy of the rotator cuff and the coraco-humeral ligament (CHL) in a-symptomatic non-elite junior tennis players with high-resolution ultrasound (US).

Methods

From August 2009 to September 2010 n = 90 a-symptomatic non-elite junior tennis players (mean age ± standard deviation: 15 ± 3) and a control group of age- and sex- matched subjects were included. Shoulder assessment with a customized standardized protocol was performed. Body mass index, dominant arm, years of practice, weekly hours of training, racket weight, grip (Eastern, Western and semi-Western), kind of strings were recorded.

Results

Abnormalities were found at ultrasound in 14/90 (15%) players. Two players had supraspinatus tendinosis, two had subacromial impingement and ten had subacromial bursitis. CHL thickness resulted comparable in the dominant and non-dominant arms (11.3 ± 4.4 mm vs. 13 ± 4.2, p > 0.05). Multivariate analysis demonstrated that no association was present among CHL thickness and the variables evaluated. In the control group, abnormalities were found at ultrasound in 6/60 (10%) subjects (sub-acromial bursitis). No statistically significant differences between players and control group were found (p = 0.71).

Conclusion

In a-symptomatic non-elite junior tennis players only minor shoulder abnormalities were found.