The Rotator Cable: Magnetic Resonance Evaluation and Clinical Correlation

Rotator cuff tear patterns: MRI appearance and its surgical relevance

A new perspective on rotator cuff anatomy has allowed a better understanding of the patterns of the different rotator cuff tears. It is essential for radiologists to be aware of these different patterns of tears and to understand how they might influence treatment and surgical approach. Our objective is to review the arthroscopy correlated magnetic resonance imaging appearance of the different types of rotator cuff tears based on current anatomical concepts.Critical relevance statement Knowledge of the characteristics of rotator cuff tears improves our communication with the surgeon and can also make it easier for the radiologist to prepare a report that guides therapeutic conduct and serves as a prognosis for the patient.Key points• There is no universally accepted classification for RC tears.• New patterns such as delamination or myotendinous junction tears have been defined.• The most difficult feature to assess in full thickness tears on MRI is the pattern.• Fatty infiltration of the RC tendons is crucial in the prognosis and outcome.• The radiological report is an effective way of communication with the surgeon.

Different types of rotator cuff tear morphology do not affect post-repair clinical outcomes in large to massive tears

OBJECTIVES

The primary aim of this current study is to evaluate the effects of rotator cuff tear morphology on clinical outcomes in large to massive tears, using a modified version of the existing classification system, with specific focus on tear symmetry and use of margin convergence.

METHODS

Patients who underwent arthroscopic repair of large to massive, full thickness rotator cuff tears were retrospectively analysed. The tear pattern was classified at the time of surgery as Type IA, Type IB, Type IIA, and Type IIB according to tear symmetry and direction of maximum tear diameter, with Type I being symmetrical and Type II being asymmetrical. Type IA (U-shaped) had greater mediolateral (ML) than anteroposterior (AP) diameter while Type IB (crescent shaped) had greater AP than ML diameter. Type IIA tears have an anterior extension towards the rotator interval while IIB tears have a posterior extension into the infraspinatus, similar to AP L-shaped tears established in the literature. Type I tears were typically repaired from medial to lateral while Type II tears were repaired diagonally. All types were repaired using double row technique, with the addition of margin convergence for Types IA and IIB, which had larger tears in the medial and lateral directions. Primary outcome measures were Oxford Shoulder Score, Constant Shoulder Score, University of California at Los Angeles Shoulder Score followed-up at 6, 12, and 24-months as well as retear rates at latest follow-up.

RESULTS

In total, 109 patients were included in the study with a mean age of 65.5 ​± ​9.4. The prevalence of each tear morphologies from Type IA to IIB was 22.0 ​%, 34.9 ​%, 27.5 ​%, and 15.6 ​%, respectively. All four groups showed statistically significant improvement from pre-operative scores in all 3 outcome measures at 24 months (p ​< ​0.001 for all). No significant difference in primary outcome measures or retear rates was detected between all 4 groups.

CONCLUSION

This study found that different types of cuff tear morphology, despite affecting surgical repair technique, does not influence clinical outcomes post-arthroscopic rotator cuff repair at mid-term follow-up.

LEVEL OF EVIDENCE

Retrospective Cohort study, Level III.

Prognostic Factors Leading to Good or Poor Outcomes Based on Functional and Radiological Findings After a Rotator Cuff Retear

BACKGROUND

A retear after rotator cuff repair is a common problem; however, there is little information related to the prognosis after a retear. In addition, some patients with retears have satisfactory outcomes, which raises the question of whether a retear leads to a poor prognosis.

PURPOSE

To identify radiological factors that influence the prognosis after a retear.

STUDY DESIGN

Case-control study; Level of evidence, 3.

METHODS

A total of 51 patients with retears confirmed by magnetic resonance imaging at 1 year after arthroscopic rotator cuff repair with a minimum follow-up of 24 months were enrolled in this study. Patients were divided into 2 groups according to whether they achieved the minimal clinically important difference for clinical outcome measures. Range of motion and radiological variables, including preoperative and postoperative anteroposterior (AP) and mediolateral (ML) tear sizes, sagittal extent of the retear, acromiohumeral distance (AHD), and degree of fatty degeneration, were analyzed using magnetic resonance imaging.

RESULTS

Overall, 36 patients were allocated to the good prognosis (GP) group and 15 to the poor prognosis (PP) group. The 2 groups had no significant differences in baseline demographics and preoperative radiological parameters. Postoperative range of motion was decreased in the PP group at the last follow-up. The AP and ML retear sizes decreased in both groups after arthroscopic rotator cuff repair, but the retear size was significantly larger in the PP group (both P < .05). The AHD increased in the GP group (P < .001) but decreased in the PP group (P = .230) postoperatively. Logistic regression analysis revealed that postoperative AHD (P = .003), fatty degeneration of the infraspinatus tendon (P = .001), posterior (P = .007) and anterior (P = .025) sagittal extent of the retear, and change in the AP tear size (P = .017) were related to poor outcomes after a retear. However, change in the ML tear size (P = .105) and middle sagittal extent of the retear (P = .878) were not related to a poor prognosis. Also, further analysis showed that posterior (P = .006) and anterior (P = .003) sagittal extent of the retear were related to rotator cable involvement.

CONCLUSION

An increased AP retear size and decreased AHD were radiological parameters that were associated with poor clinical outcomes after a retear. In particular, patients who had posterior and anterior sagittal extent of the retear, possibly with rotator cable involvement and more severe fatty degeneration of the infraspinatus tendon, showed worse outcomes.

Delamination in rotator cuff tears: Explanation of etiology through anatomical dissection

The prognostic significance of delaminated rotator cuff tears remains controversial. However, as the surgical goal is to maximize the contact area between layers, the macroscopic appearance of partial delaminated rotator cuff tears is essential. The aim of this anatomical study was to investigate the morphology of delaminated rotator cuff tears. We hypothesized that delamination zones at the intersection of the supraspinatus and infraspinatus tendon fibers are the origin of articular-side degenerative rotator cuff tears. Forty anatomical specimens were evaluated in this study. The supraspinatus and infraspinatus muscles were dissected, the origins were meticulously worked out and followed to their insertions at the humeral head. Fiber exchanges, overlays and delamination zones between the supraspinatus and infraspinatus muscles were photographically documented and measured. Delamination of rotator cuff tears can be classified into articular-side and bursal-side tears. The articular-layer consists of capsuloligamentous tissue, which included the rotator-cable/rotator-crescent complex, the joint capsule and a small part of the supraspinatus tendon. The bursal-side layer represents the tendinous tissue, which consists of the parallel, tendinous parts of the supraspinatus and infraspinatus muscles. Delamination of rotator cuff tears can be classified into articular-side and bursal-side tears. Present model of degenerative tears might explain the high prevalence of articular-side tears, which expand into the rotator-cable/rotator-crescent complex. It may be important for surgeons to incorporate these anatomical findings and considerations into the surgical planning.

[Partial-Thickness Tear of Supraspinatus and Infraspinatus Tendon Revisited: Based on MR Findings]

The interpretation of MRI of partial-thickness rotator cuff tears can be challenging. This review describes the anatomic considerations for diagnosing partial-thickness tears, especially supraspinatus and infraspinatus tendon and summarizes the classification of partial-thickness rotator cuff tears, as well as provides an overview on partial-thickness tears with delamination.

Interobserver reliability of the rotator cable and its relationship to rotator cuff congruity

BACKGROUND

This study evaluated the presence of the rotator cable intraoperatively and compared its prevalence according to both patient age and rotator cuff integrity. The study hypothesis was that the cable would be more prevalent in older patients and patients with partial-thickness tears.

METHODS

Patients who were undergoing shoulder arthroscopy and were aged at least 16 years were included in this study, whereas those who had a cuff tear of more than 1 tendon or who had a video with poor visualization of the rotator cuff insertion were excluded. Intraoperative videos were collected, deidentified, and distributed to 7 orthopedic surgeons to define rotator cable and cuff tear characteristics.

RESULTS

A total of 58 arthroscopic videos (average patient age, 46 years; range, 16-75 years) were evaluated. The observers were in the most agreement on identifying the presence of a cable, with a κ coefficient of 0.276. Patients with the rotator cable were significantly older than those without it (mean age, 52.1 years vs. 42.5 years; P = .008), and a positive and significant correlation was found between rotator cable presence and increasing patient age (r = 0.27, P = .04). A significant association was noted between tear degree and cable presence (P = .002). There was no significant association with cable presence in patients with a full-thickness tear.

CONCLUSIONS

In this study, an intraoperative analysis was performed to define the presence of the rotator cable and correlate this with both patient age and rotator cuff integrity. The hypothesis was confirmed in that patients older than 40 years had a significantly higher rotator cable prevalence.

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.

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.