Does magnetic resonance imaging appearance of supraspinatus muscle atrophy change after repairing rotator cuff tears?

A modified Patte classification system for rotator cuff tendon retraction to predict reparability and tendon healing in arthroscopic rotator cuff repair

PURPOSE

The purpose of this study was to propose a modified Patte classification system for tendon retraction, including the cut-off points for predicting reparability and rotator cuff healing after arthroscopic rotator cuff repair (ARCR) and assess its prediction accuracy and measurement reliability.

METHODS

This retrospective study included 463 consecutive patients scheduled to undergo ARCR for full-thickness supraspinatus tears. Receiver operating characteristic (ROC) curve analysis was used to determine the cut-off points for predicting reparability and tendon healing. The modified Patte classification system, in which these cut-off points were combined with the original Patte classification, classified the tendon retraction as stages I-V. The prediction accuracy of reparability and tendon healing was assessed using the area under the curve (AUC). Measurement reliability was determined using Cohen's κ statistics.

RESULTS

Of the 402 included patients, 32 rotator cuff tears were irreparable and 71 of the remaining 370 were diagnosed with healing failure. ROC analysis determined the cut-off point of reparability at the medial one-fifth and that of tendon healing at the medial one-third of the humeral head. The AUC of the modified Patte classification for predicting reparability and tendon healing was 0.897 (excellent) and 0.768 (acceptable), respectively. Intra-rater reliability was almost perfect (mean κ value: 0.875), and inter-rater reliability was substantial (0.797).

CONCLUSION

Diagnostic performance of the modified Patte classification system was excellent for reparability and acceptable for rotator cuff healing, with high measurement reliability. The modified Patte classification system can be easily implemented in clinical practice for planning surgical procedures and counselling patients in the day-by-day clinical work.

LEVEL OF EVIDENCE

Level III.

ACR Appropriateness Criteria® Chronic Shoulder Pain: 2022 Update

Chronic shoulder pain is an extremely common presenting complaint. Potential pain generators include the rotator cuff tendons, biceps tendon, labrum, glenohumeral articular cartilage, acromioclavicular joint, bones, suprascapular and axillary nerves, and the joint capsule/synovium. Radiographs are typically the initial imaging study obtained in patients with chronic shoulder pain. Further imaging may often be required, with modality chosen based on patient symptoms and physical examination findings, which may lead the clinician to suspect a specific pain generator. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision process support the systematic analysis of the medical literature from peer reviewed journals. Established methodology principles such as Grading of Recommendations Assessment, Development, and Evaluation or GRADE are adapted to evaluate the evidence. The RAND/UCLA Appropriateness Method User Manual provides the methodology to determine the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where peer reviewed literature is lacking or equivocal, experts may be the primary evidentiary source available to formulate a recommendation.

Editorial Commentary: Monitoring Tendon and Muscle Recovery After Rotator Cuff Repair Using Diagnostic Ultrasound Demonstrates that Early Repair is Beneficial for Many Patients With Reparable Tears

Rotator cuff repair is performed to effect healing of the enthesis; to restore shoulder comfort, strength, and function; to prevent tear propagation; and to prevent progression of atrophic muscle changes (fatty degeneration, fatty infiltration, and fatty atrophy) that eventually occur. Non-retracted and moderately retracted rotator cuff tears usually heal after repair, and muscle atrophy may recover over time. It follows that early rotator cuff repair is beneficial for many patients with chronic but reparable rotator cuff tears. Diagnostic ultrasound can provide quantitative information about the recovery of both muscle and tendon and represents a viable alternative to magnetic resonance imaging for evaluating healing after rotator cuff repair.

Nerve and Muscle Abnormalities

Muscle atrophy in shoulders with rotator cuff tendon tears is a negative prognosticator, associated with decreased function, decreased reparability, increased retears after repair, and poorer outcomes after surgery. Muscle edema or atrophy within a neurologic distribution characterizes denervation. Because most nerve entrapments around the shoulder are not caused by mass lesions and show no nerve findings on routine MR imaging sequences, pattern of muscle denervation is often the best clue to predicting location of nerve dysfunction, which narrows the differential diagnosis and guides clinical management. The exception is suprascapular nerve compression in the spinoglenoid notch caused by a compressing cyst.

Relation of Superficial and Deep Layers of Delaminated Rotator Cuff Tear to Supraspinatus and Infraspinatus Insertions

BACKGROUND

It remains unclear whether the deep layer of the rotator cuff is an articular layer of the supraspinatus (SS) or infraspinatus (IS), rotator cable, or superior capsule. Therefore, this study aimed to analyse the relationship between occupation ratios and delamination patterns of rotator cuff tears (RCTs). We hypothesised that the deep layers are related to the occupation ratios of the deep SS and IS sections.

MATERIALS AND METHODS

A total of 265 patients with RCTs were retrospectively enrolled between 2013 and 2017 and divided into four groups: A, non-delaminated tear; B, delaminated tear with the deep layer equally retracted to the superficial layer; C, delaminated tear with the deep layer more retracted; D, delaminated tear with the superficial layer more retracted. Muscle volume was evaluated by measurement of each occupation ratio of the SS and IS, and the IS muscle was additionally divided into two areas, deep and superficial.

RESULTS

The SS occupation ratio was significantly lower in group C than in the other groups (p = 0.009). Conversely, comparison of the IS occupation ratios revealed no significant intergroup differences. The occupation ratio of the superficial IS was significantly lower in group D than in the other groups (p = 0.003). In group C, the occupation ratios of the deep IS section were significantly decreased according to RCT size (p = 0.034).

CONCLUSION

Our findings demonstrate that the superficial layers are related to the IS superficial section and the deep layers to the SS and IS deep sections.

LEVEL OF STUDY

IV.

Restoration of supraspinatus and infraspinatus deep plane occupation ratios was greater in delaminated tears than in non-delaminated tears after rotator cuff repair

Total 132 patients who underwent arthroscopic suture bridge repair were divided into two groups: group A, non-delaminated tears; group B, deep layer, more retracted, delaminated tears. In addition, group B were divided into two subgroups: group I (≤2-cm) and group II (>2-cm). Muscle volume was evaluated by measuring the occupation ratio and restoration of the rotator cuff muscle was defined as the difference between the preoperative and postoperative occupation ratios. The restoration of the SS and IS deep plane occupation ratios was greater in >2-cm-sized delaminated tears than in ≤2-cm-sized delaminated and non-delaminated tears.

Postoperative residual pain is associated with a high magnetic resonance imaging (MRI)-based signal intensity of the repaired supraspinatus tendon

PURPOSE

To assess patients with and without postoperative residual pain and to compare clinical function and magnetic resonance imaging (MRI) appearance of the repaired supraspinatus tendon between patients with and without pain.

METHODS

One-hundred and seventeen patients with supraspinatus tear were included in this study. Visual Analog Scale (VAS) scores for pain were assessed at a follow-up of at least 1 year. Patients with residual shoulder pain were enrolled in the residual pain group (RP group) and patients without pain enrolled in the no pain group (NP group). The American Shoulder and Elbow Surgeons (ASES) shoulder evaluation form, the modified University of California at Los Angeles (UCLA) score and the Fudan University Shoulder Score (FUSS) were also used to evaluate shoulder function. MRI examinations were performed to evaluate rotator cuff integrity according to the Sugaya method, and muscular hypotrophy, fatty infiltration, and signal/noise quotient (SNQ) of the rotator cuff tendon.

RESULTS

Thirty-five patients had residual pain (RP group) and 82 patients had no pain (NR group). At the final follow-up, there was a significant difference in ASES (92 ± 8 points vs 76 ± 10 points; p < 0.001), UCLA (32 ± 3 points vs 28 ± 3 points; p < 0.001), FUSS (90 ± 7 points vs 80 ± 9 points; p < 0.001) and strength (9 ± 3 kg vs 6 ± 2 kg; p < 0.001) between the NP group and the RP group, respectively. Postoperative MRI revealed that there was no significant difference in the retear rate (9.8% vs 8.6%; ns), the muscular hypotrophy (ns), and the fatty infiltration index (0.9 ± 0.2 vs 0.9 ± 0.2; ns) between the NP and the RP groups, respectively. The postoperative tendon SNQ of the RP group was significantly higher than that of the NP group (4.6 ± 2.5 vs 3 ± 1.7; p < 0.001). There was a significant association between tendon SNQ and VAS for this cohort ([Formula: see text] = 0.29; p = 0.003).

CONCLUSION

Postoperative residual pain is associated with a high MRI signal intensity of the repaired supraspinatus tendon. Since high signal intensity of tendon tissue indicates degenerated tendon tissue quality, it highlighted the necessity of debriding the degenerated rotator cuff tendon tissue.

LEVEL OF EVIDENCE

III.

The supraspinatus occupation ratios of both the ≥ 50% articular- and bursal-side partial-thickness rotator cuff tears were low and the infraspinatus occupation ratio of the ≥ 50% bursal-side partial-thickness rotator cuff tears was low

PURPOSE

The purpose of this study was to analyze the relationship between the occupation ratio and partial-thickness rotator cuff tears.

METHODS

The study included and retrospectively investigated 683 patients with partial-thickness rotator cuff tears between 2013 and 2017. Fifty patients with impingement syndrome were also enrolled as the control group for normal-population comparison. The participants were divided into five groups: Group A, control group; Group B, < 50% articular-side tears; Group C, ≥ 50% articular-side tears; Group D, < 50% bursal-side tears; and Group E, ≥ 50% bursal-side tears. Muscle volume was evaluated by measurement of each occupation ratio of the supraspinatus and infraspinatus tendons on the most lateral view of the T1-weighted oblique-sagittal images in which the scapular spine remained in contact with the scapular body.

RESULTS

Fifty patients were enrolled in Group A. A total of 683 patients with Partial thickness rotator cuff tear were divided and classified into the following groups: 272 into Group B, 153 into Group C, 161 into Group D, and 97 into Group E. The supraspinatus occupation ratios of all partial-thickness rotator cuff tear groups were significantly lower than those of the control group. Furthermore, the supraspinatus occupation ratios of Groups C and E (≥ 50% partial-thickness rotator cuff tears) were significantly lower than those of Groups B and D (< 50% partial-thickness rotator cuff tears). However, the infraspinatus occupation ratio of only Group E was significantly lower than that of the other groups.

CONCLUSION

The supraspinatus occupation ratios of both the ≥ 50% articular- and bursal-side partial-thickness rotator cuff tears were lower than those of the other partial-thickness rotator cuff tears. Conversely, the infraspinatus occupation ratio of only the ≥ 50% bursal-side partial-thickness rotator cuff tears was low.

LEVEL OF EVIDENCE

IV.

Reliability of Ultrasound Measurement of Muscle Thickness in Patients with Supraspinatus Tendon Pathology

Objectives of the study were to observe supraspinatus muscle thickness in patients with supraspinatus tendon pathology using ultrasound (US) and examining inter- and intra-rater reliability, and to compare muscle thickness with cross-sectional area (CSA) and occupation ratio measured by both US and magnetic resonance imaging (MRI). The investigation was designed as a prospective cohort study. Two groups of patients were included in the study: 43 patients with tendon rupture and 44 patients without tendon rupture as a control group. A written consent was obtained from all patients. In both groups, muscle thickness, CSA and occupation ratio were measured with US, and CSA and occupation ratio with MRI. Study results showed statistically significant between-group differences. The mean supraspinatus muscle thickness measured by US was 14.01 mm and 19.83 mm in patients with and without tendon rupture, respectively. CSA and occupation ratio measured by US and MRI also showed statistically significant between-group differences. Pearson correlation coefficient between supraspinatus thickness and occupation ratio and CSA measured by US and MRI showed strong to moderate correlation. US measurements showed moderate to strong intra- and inter-rater reliability. In conclusion, supraspinatus muscle thickness measurement by US is a reliable method for muscle atrophy evaluation and strongly correlates with other acknowledged methods.

Do magnetic resonance imaging and computed tomography provide equivalent measures of rotator cuff muscle size in glenohumeral osteoarthritis?

BACKGROUND

Rotator cuff muscle volume is associated with outcomes after cuff repair and total shoulder arthroplasty. Muscle area on select magnetic resonance imaging (MRI) slices has been shown to be a surrogate for muscle volume. The purpose of this study was to determine whether computed tomography (CT) provides an equivalent measurement of cuff muscle area to a previously validated MRI measurement.

METHODS

We included 30 patients before they were undergoing total shoulder arthroplasty with both preoperative CT and MRI scans performed within 30 days of one another at 1 institution using a consistent protocol. We reoriented CT sagittal and MRI sagittal T1 series orthogonal to the scapular plane. On both CT and MRI scans, we measured the area of the supraspinatus, infraspinatus-teres minor, and subscapularis on 2 standardized slices as previously described. We calculated intraclass correlation coefficients and mean differences.

RESULTS

For the 30 subjects included, when MRI and CT were compared, the mean intraclass correlation coefficients were 0.989 (95% confidence interval [CI], 0.976-0.995) for the supraspinatus, 0.978 (95% CI, 0.954-0.989) for the infraspinatus-teres minor, and 0.977 (95% CI, 0.952-0.989) for the subscapularis. The mean differences were 0.2 cm² (95% CI, 0.0-0.4 cm²) for the supraspinatus (P = .052), 0.8 cm² (95% CI, 0.1-1.4 cm²) for the infraspinatus-teres minor (P = .029), and -0.3 cm² (95% CI, -1.2 to 0.5 cm²) for the subscapularis (P = .407).

CONCLUSION

CT provides nearly equivalent measures of cuff muscle area to an MRI technique with previously validated reliability and accuracy. While CT underestimates the infraspinatus area as compared with MRI, the difference is less than 1 cm² and thus likely clinically insignificant.

Large Critical Shoulder Angle Has Higher Risk of Tendon Retear After Arthroscopic Rotator Cuff Repair

BACKGROUND

The critical shoulder angle (CSA) is the angle created between the superior and inferior bone margins of the glenoid and the most lateral border of the acromion. A few studies recently investigated the relation between CSA and functional outcomes after rotator cuff repair. However, there is a lack of research investigating the effect of CSA on postoperative tendon integrity after rotator cuff repair.

PURPOSE

To assess the effects of the CSA on postoperative tendon integrity after rotator cuff repair.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

All patients who underwent rotator cuff repair for full-thickness supraspinatus tears by 1 senior surgeon between January 2010 and January 2014 were included in this study. All patients had standardized anteroposterior shoulder radiographs the day before surgery. CSA and acromial index (AI) were measured. AI was derived by measuring the distance from the glenoid plane to the lateral border of the acromion and dividing it by the distance from the glenoid plane to the lateral aspect of the humeral head. Functional scores-including American Shoulder and Elbow Surgeons shoulder evaluation form, modified University of California at Los Angeles score, Constant-Murley score, and visual analog scale for pain-were used to evaluate shoulder function at a minimum follow-up of 2 years. Meanwhile, magnetic resonance imaging examinations were performed to evaluate rotator cuff integrity according to the Sugaya method and the signal/noise quotient (SNQ) of the rotator cuff tendon.

RESULTS

A total of 90 patients were included in this study: 42 patients with a single-row repair and 48 with a double-row repair. There was a significant positive correlation between CSA or AI and tendon SNQ. On the basis of CSA, the patients were divided into 2 groups: large CSA (>38°) and control (CSA ≤38°). At final follow-up, the large CSA group and the control CSA group demonstrated no significant differences in American Shoulder and Elbow Surgeons, University of California at Los Angeles, Constant, and visual analog scale scores. Postoperative magnetic resonance imaging revealed that the large CSA group had 9 cases of retear, with a significantly higher retear rate than the control group (15% vs 0%, P = .03). Furthermore, the tendon SNQ of the large CSA group was significantly greater than that of the control group.

CONCLUSION

CSA did not appear to influence postoperative functional outcomes, while those in the large CSA group had poor tendon integrity after rotator cuff repair. These findings indicate that a large CSA is associated with an increased risk of rotator cuff tendon retear after repair.

What Is the Appropriate Reference for Evaluating the Recovery of Supraspinatus Muscle Atrophy After Arthroscopic Rotator Cuff Repair? The Occupation Ratio of the Supraspinatus May Change After Rotator Cuff Repair Without Volumetric Improvement

BACKGROUND

Supraspinatus muscle atrophy is typically assessed by the occupation ratio of the cross-sectional area of the muscle belly to the supraspinatus fossa at the medial border of the coracoid process in a slice along the oblique-sagittal plane on MRI. Previous studies have shown that the occupation ratio of the supraspinatus changed soon after rotator cuff repair compared with before surgery. However, no studies have examined the perioperative change in the muscle volume assessed with 3-dimensional measurement.

PURPOSE

To compare the volume of the supraspinatus muscle before and soon after surgery by using 3-dimensional imaging and to elucidate whether the changes in the occupation ratio represent corresponding changes in the muscle volume.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

Thirty shoulders of patients who underwent arthroscopic rotator cuff repair were evaluated. T2-weighted images were obtained before surgery and 2 weeks after surgery. After the muscle and its tendon borders were plotted, the supraspinatus and its tendon were segmented with interactive thresholding in all slices. The 3-dimensional images were then reconstructed and the volumes calculated. Changes in the muscle volume and the occupation ratio were evaluated via 3-dimensional and 2-dimensional image assessments. The 3-dimensional and 2-dimensional findings before and after surgery were compared by use of paired t tests.

RESULTS

The mean muscle volume did not change significantly at a time point soon after surgery in any group. In patients with little medial retraction (n = 7) or isolated detachment at the superior facet (n = 17), no significant differences were noted in the occupation ratio after surgery compared with before surgery. In contrast, in patients with moderate medial retraction (n = 23) or extended tearing in the transverse direction (n = 13), the occupation ratio increased significantly.

CONCLUSION

Although the muscle volume did not change soon after surgery compared with the preoperative values, in patients with moderate medial retraction or extended tearing in the transverse direction, the occupation ratio increased, probably due to lateral traction of the supraspinatus muscle. We recommend that MRI findings obtained soon after surgery be used as the time-zero reference for evaluating the postoperative changes in the supraspinatus.