Delayed Anticipatory Muscle Activation in Rotator Cuff Tendinopathy

BACKGROUND

Previous research investigating rotator cuff (RC) tendinopathy has usually focused on pathoanatomy. The pathologic response to anticipatory postural adjustments (APAs) has not yet been investigated.

PURPOSE/HYPOTHESIS

To explore changes in APAs as detected by pre-emptive activation of shoulder muscles during ball catching. It was hypothesized that anticipatory muscle activation (AMA) would be present in the unaffected shoulder but delayed or absent in the affected shoulder in patients with RC tendinopathy.

STUDY DESIGN

Controlled laboratory study.

METHODS

This study included 21 RC tendinopathy patients with a mean age of 49.5 years. Patients were required to grab a ball embedded with an electromyography sensor when it dropped on their hand, and surface electromyography signals were recorded from the infraspinatus, upper trapezius, anterior deltoid, and biceps. The trials utilized 2 balls, weighing 200 g and 500 g. Each ball was used in 2 trials, 1 involving a number count preceding the ball drop (predictable) and the other involving a sudden drop (unpredictable). The onsets of AMA between the affected and unaffected limbs were compared.

RESULTS

Regardless of the experimental condition, significantly delayed AMA onsets were identified in all investigated muscles of the affected side compared with those of the unaffected side, except for the biceps muscle in the 500-g predictable trial. For the infraspinatus, the mean onset time in the 200-g predictable trial was -141.0 ± 60.2 ms on the affected side and -211.9 ± 67.1 ms on the unaffected side (P < .001); in the 200-g unpredictable trial this value was -139.5 ± 54.9 ms on the affected side and -199.5 ± 56.2 ms on the unaffected side (P < .001).

CONCLUSION

Delayed AMA was observed in the affected shoulder compared with the unaffected shoulder in patients with RC tendinopathy, not only in the RC muscle but also in the periscapular and upper arm muscles. This may indicate that central hypoexcitability is partly responsible.

CLINICAL RELEVANCE

The basis for RC tendinopathy treatment should not be limited to the tendon pathoanatomy. Delayed AMA around the shoulder joint could provide insight into potential mechanisms related to the central nervous system.

Relationship between fatty infiltration and gene expression in patients with medium rotator cuff tear

BACKGROUND

Fatty infiltration (FI) is a key prognostic factor that affects outcomes after rotator cuff repair and is radiologically evaluated using the Goutallier classification. The purpose of this study was to assess alterations in gene and protein expression according to the Goutallier classification in the supraspinatus muscle and any relationships among various gene expression profiles.

METHODS

Twenty-four samples of the supraspinatus muscle from 12 patients with a high FI grade (grade 3 or 4) and 12 patients with a low FI grade (grade 1 or 2) with medium-sized tears were acquired during arthroscopic surgery. Alterations in the expression of genes and proteins associated with adipogenesis, fibrosis, inflammation, and muscle atrophy were compared between the high- and low-FI groups using reverse-transcription quantitative polymerase chain reaction, Western blotting, and immunohistochemistry.

RESULTS

mRNA expression of not only the adipogenic genes (peroxisome proliferator-activated receptor γ and CCAAT/enhancer-binding protein α; P < .001 and P = .020) but also the fibrosis-related gene (α-smooth muscle actin; P < .001), inflammation-related genes (interleukin [IL]-1β and tumor necrosis factor α; P = .041 and P = .039), and muscle atrophy-related genes (atrogin 1 and myostatin; P = .006 and P < .001) was higher in the high-FI group compared with that in the low-FI group. In addition, adipogenic gene expression was significantly correlated with the expression of other categories of genes (all P < .05, except atrogin 1). A correlation of gene and protein expression was observed for IL-1β (P = .027) and myostatin (P = .029).

CONCLUSIONS

The radiologic grading of FI was associated with the expression of various genes, including adipogenic, fibrotic, inflammatory, and atrophy-related genes, and these genes were closely correlated with each other in terms of expression. This information could be helpful in patient counseling.

Automated rotator cuff tear classification using 3D convolutional neural network

Rotator cuff tear (RCT) is one of the most common shoulder injuries. When diagnosing RCT, skilled orthopedists visually interpret magnetic resonance imaging (MRI) scan data. For automated and accurate diagnosis of RCT, we propose a full 3D convolutional neural network (CNN) based method using deep learning. This 3D CNN automatically diagnoses the presence or absence of an RCT, classifies the tear size, and provides 3D visualization of the tear location. To train the 3D CNN, the Voxception-ResNet (VRN) structure was used. This architecture uses 3D convolution filters, so it is advantageous in extracting information from 3D data compared with 2D-based CNNs or traditional diagnosis methods. MRI data from 2,124 patients were used to train and test the VRN-based 3D CNN. The network is trained to classify RCT into five classes (None, Partial, Small, Medium, Large-to-Massive). A 3D class activation map (CAM) was visualized by volume rendering to show the localization and size information of RCT in 3D. A comparative experiment was performed for the proposed method and clinical experts by using randomly selected 200 test set data, which had been separated from training set. The VRN-based 3D CNN outperformed orthopedists specialized in shoulder and general orthopedists in binary accuracy (92.5% vs. 76.4% and 68.2%), top-1 accuracy (69.0% vs. 45.8% and 30.5%), top-1±1 accuracy (87.5% vs. 79.8% and 71.0%), sensitivity (0.92 vs. 0.89 and 0.93), and specificity (0.86 vs. 0.61 and 0.26). The generated 3D CAM provided effective information regarding the 3D location and size of the tear. Given these results, the proposed method demonstrates the feasibility of artificial intelligence that can assist in clinical RCT diagnosis.

Influence of Smoking on the Expression of Genes and Proteins Related to Fat Infiltration, Inflammation, and Fibrosis in the Rotator Cuff Muscles of Patients With Chronic Rotator Cuff Tears: A Pilot Study

PURPOSE

To evaluate the altered gene and protein expression patterns in the rotator cuff muscles of smokers and non-smokers with rotator cuff tears and to identify the smoking-associated key genetic factor(s) involved in rotator cuff muscle physiology.

METHODS

Twenty-four samples of rotator cuff muscle from 12 current heavy smokers (mean age 61.8 ± 5.1 years) and age- and sex-matched 12 non-smokers (mean age 61.8 ± 6.9 years) with medium-sized tears were acquired during arthroscopic surgery. As a statistical method, the propensity score matching technique was used to select control group by 1:1 matching for age and sex. Inclusion criteria were patients who underwent arthroscopic repair for medium-sized full-thickness rotator cuff tears and those that were current smokers with a smoking history >20 packs/year. Patients lacking medium-sized tears, those with recent steroid injection history, isolated subscapularis tear, preoperative stiff shoulder, acute traumatic tear, or previous surgery on the same shoulder, or those that declined to participate were excluded. Alterations in the expression of genes and proteins associated with myogenesis, inflammation, adipogenesis, and muscle fibrosis were compared between smokers and non-smokers with reverse-transcription quantitative polymerase chain reaction, western blotting, and immunohistochemistry.

RESULTS

Histologic analysis revealed increased inflammation and remarkable fat accumulation and fibrogenesis in the rotator cuff muscle from smokers compared with that from non-smokers. The mRNA expression levels of inflammatory high mobility group box 1 (HMGB1; P = .043), adipogenic CCAAT/enhancer-binding protein alpha (P = .046) and peroxisome proliferator-activated receptor gamma (PPARγ; P = .048), myogenic differentiation 1 (P = .032), fibrogenic alpha-smooth muscle actin (α-SMA; P = .033), and metalloproteinase 9 (P = .036) were significantly greater in samples from smokers than from non-smokers. A correlation was observed between gene and protein expression of HMGB1 (P = .034), PPARγ (P = .021), and α-SMA (P = .021).

CONCLUSIONS

Smokers with rotator cuff tears showed high inflammation, large fat infiltration, and fibrosis in rotator cuff muscle that is associated with the increased expression of HMGB1, PPARγ, and α-SMA, respectively.

LEVEL OF EVIDENCE

Case control study (Prognostic level III).

Effect of Fatty Acid-Binding Protein 4 Inhibition on Rotator Cuff Muscle Quality: Histological, Biomechanical, and Biomolecular Analysis

BACKGROUND

A rotator cuff tear (RCT) induces fatty acid-binding protein 4 (FABP4) expression, resulting in ectopic fat accumulation in the rotator cuff muscle.

PURPOSE

To evaluate whether FABP4 inhibition reduces fatty infiltration and improves muscle physiology after RCT in a rat model.

STUDY DESIGN

Controlled laboratory study.

METHODS

Human supraspinatus muscle and deltoid muscle tissues were acquired from patients with RCTs during arthroscopic surgery, and FABP4 expression in the supraspinatus muscle was evaluated as compared with the intact deltoid muscle. A rat RCT model was established by detaching the supraspinatus tendon, after which a specific FABP4 inhibitor was locally injected into the supraspinatus muscle 4 times at 3-day intervals starting 2 weeks after the surgery. Body weight and blood glucose levels were measured at 2 and 4 weeks after the RCT, and the mRNA and protein expressions of various target molecules (including FABP4), histological changes, and biomechanical tensile strength were assessed in the supraspinatus muscles at 4 weeks after the RCT.

RESULTS

The expression of human FABP4 was significantly increased in the torn rotator cuff muscle as compared with the intact deltoid muscle. In the rat model, the mRNA and protein expressions of FABP4 and HIF1α were significantly increased by the RCT as compared with the control. The FABP4 inhibitor treatment significantly decreased FABP4 expression when compared with the vehicle treatment; however, HIF1α expression was not significantly decreased versus the vehicle treatment. Histologically, RCT induced noticeable muscle fatty infiltration, which was remarkably reduced by the local injection of the FABP4 inhibitor. Biomechanically, the tensile strength of the rotator cuff muscle after the RCT was significantly improved by the FABP4 inhibitor in terms of load to failure and total energy to failure.

CONCLUSION

RCT induces FABP4 expression in human and rat rotator cuff muscles. The FABP4 inhibitor drastically decreased the histological fatty infiltration caused by RCT and improved the tensile strength of the rotator cuff muscle.

CLINICAL RELEVANCE

FABP4 inhibitor may have a beneficial effect on the muscle quality after RCT.

Factors associated with needle breakage of antegrade suture passer and effect of intratendinous remnant needle tip on clinical outcomes after arthroscopic rotator cuff repair

Objective

The aim of this study was to evaluate factors associated with the needle breakage of antegrade suture passer and the effect of intratendinous remnant needle tip on clinical outcomes after rotator cuff repair.

Methods

We retrospectively reviewed 283 patients (138 men and 145 women; mean age: 59.7 ± 9.3 years) who underwent arthroscopic repair for full-thickness rotator cuff tear. We evaluated the characteristics of 16 patients in whose needle tip had been broken and embedded and remained in the rotator cuff (remnant needle group) and compared them with the remaining 267 patients (control group). Afterwards, another 64 patients were selected from control group (1:4 matching) after propensity score matching (PSM). The groups were compared anatomically with MRI or ultrasonography and functionally (serial pain VAS and ROM; ASES, Constant, UCLA and SST scores) at a minimum follow-up of 1 year.

Results

The remnant needle group showed preoperative thicker tendon (6.72 mm vs 5.33 mm, p = 0.047), higher tendinosis (mean grade, 1.88 vs. 1.43, p = 0.029), and more frequent delaminated tears (p = 0.035) compared with control group. When we compare the clinical outcomes after PSM, the initial pain VAS of the remnant needle tip group was higher up to 3 months (pain VAS: 4.13 ± 2.07 vs 2.48 ± 1.61 (p = 0.032) at 5 weeks and 3.79 ± 2.12 vs 2.25 ± 1.76 (p = 0.044) at 3 months), however the difference disappeared after 6 months postoperatively. In final evaluation, there was no significant differences in every outcome parameters (all p > 0.05).

Conclusion

Breakage of the needle of the antegrade suture passer occurred more frequently in the thicker tendon, higher tendinosis, and delaminated tears. The retained broken needle tip was associated with higher pain scores during the early postoperative period, but revealed no difference in final outcomes by using PSM.

Level of Evidence

Level III, Therapeutic Study

Changes in Perianchor Cyst Formation Over Time After Rotator Cuff Repair: Influential Factors and Outcomes

BACKGROUND

There is a lack of knowledge about the changes in perianchor cysts over time and the factors related to perianchor cysts.

PURPOSE

To evaluate the changes in perianchor cyst formation and anchor absorption over time after arthroscopic rotator cuff repair with a biocomposite suture anchor and to evaluate the factors affecting perianchor cyst persistence and their relationship with patient outcomes.

STUDY DESIGN

Case-control study; Level of evidence, 3.

METHODS

Forty consecutive patients (mean age, 61.10 ± 5.79 years) who underwent arthroscopic repair for medium- to large-sized rotator cuff tears using a single type of biocomposite (poly-L-lactic acid/polyglycolic acid-beta tricalcium phosphate) medial-row anchor were prospectively enrolled. Postoperative magnetic resonance imaging (MRI) at 2 different time points (6 and 18 months) was performed, and perianchor cyst formation, anchor absorption, and healing failures were evaluated using postoperative MRI. Demographic and clinical data were collected, and functional outcomes at a minimum of 18 months after surgery were assessed.

RESULTS

Perianchor cysts were observed in 24 patients (60.0% total; grade 1: 35.0%; grade 2: 10.0%; grade 3: 7.5%; grade 4: 7.5%) at 6 months, and 7 patients (18.4% total; grade 1: 7.9%; grade 2: 5.3%; grade 3: 2.6%; grade 4: 2.6%) had a persistent perianchor cyst at 18 months after surgery. No anchors were absorbed at 6 months, but 73.7% of patients revealed complete or near-full absorption at 18 months. Patients with persistent perianchor cysts showed a significantly larger tear size in the anteroposterior dimension ( P = .002) and greater retraction ( P < .001). There were no differences in healing failures and functional outcomes between patients with and without persisting perianchor cysts (all P > .05). No differences were found in perianchor cyst formation and anchor absorption between anchors inserted in the greater tuberosity and the lesser tuberosity (all P > .05).

CONCLUSION

The incidence and severity of perianchor cysts decreased with time, and most biocomposite suture anchors were absorbed at 18 months after surgery. Persisting perianchor cysts correlated with a larger tear size in the anteroposterior dimension and greater retraction.

Increased levels of interleukin-6 are associated with lymphocytosis in bronchoalveolar lavage fluids of idiopathic nonspecific interstitial pneumonia

Local overexpression of interleukin-6 (IL-6) experimentally induces lymphocytic infiltration in the bronchial tree of rat. Among idiopathic interstitial pneumonia (IIP), nonspecific interstitial pneumonia/fibrosis (NSIP) has an increased number of lymphocytes in bronchoalveolar lavage (BAL) fluid when compared with usual interstitial pneumonia (UIP). To reveal a relation of IL-6 with the lymphocyte infiltration of NSIP, IL-6 was measured in BAL fluids of idiopathic NSIP (n = 7), idiopathic UIP (n = 16), and normal control subjects (n = 45). IL-6-producing sites were assessed by IL-6 protein stain on biopsy specimens of NSIP, UIP, and normal lung of mediastinal tumors. Lymphocyte numbers and IL-6 levels in BAL fluids were higher in NSIP than those in UIP (p < 0.01, respectively), which were also higher when compared with those of normal control subjects (p < 0.01, respectively). In NSIP, the levels of IL-6 correlated with the number of lymphocytes (r = 0.93, p < 0.01). UIP cases were divided into two groups: high-UIP (n = 7) or low-UIP (n = 9) according to IL-6 levels greater than or within the 95 percentile of normal control subjects, respectively. The high-UIP group had BAL lymphocytosis when compared with the low-UIP group (p < 0.05). IL-6 stained on epithelial cells of the bronchial tree and on alveolar macrophages of NSIP and UIP. In conclusion, the lymphocytosis in BAL fluid of patients with NSIP and a subgroup of UIP is associated with the high levels of IL-6 and its sources are the epithelial cells of the small airway and the alveolar macrophages.

Interleukin (IL)-5 downregulates tumor necrosis factor (TNF)-induced eotaxin messenger RNA (mRNA) expression in eosinophils. Induction of eotaxin mRNA by TNF and IL-5 in eosinophils

An eotaxin is a chemoattractant specific for eosinophils that are known to play a role in helminth infection and allergic responses. Although several cellular sources have been reported to produce eotaxin, it would be interesting to know whether eosinophils are able to produce their own eotaxin and participate in recruitment of themselves in response to inflammation. To this end, a cloned eotaxin complementary DNA was transcribed in vitro to use as a probe for detecting eotaxin messenger RNA (mRNA), and eotaxin protein levels were determined by enzyme-linked immunosorbent assay. Eotaxin mRNA was, as analyzed by in situ hybridization, rarely detectable in unstimulated eosinophils, but was strongly induced in eosinophils when stimulated with tumor necrosis factor (TNF). Interleukin (IL)-5, which is known to be a major factor of eosinophil survival in vivo and in vitro, was also able to induce a modest level of eotaxin mRNA but inhibited TNF-induced eotaxin mRNA expression in a dose-response manner. Dexamethasone inhibited TNF-induced eotaxin mRNA expression. This result was consistent with that from reverse transcription/polymerase chain reaction followed by Southern blot analysis. Unlike the little expression of eotaxin mRNA in the absence of stimuli, the measurement of eotaxin protein revealed that a considerable amount of eotaxin protein was constitutively produced in unstimulated eosinophils. Its expression was upregulated by TNF and IL-5 as well. However, the inhibitory effect of IL-5 on TNF-mediated eotaxin protein production was not as pronounced as that on eotaxin mRNA induction. Collectively, these data reflect the complex physiology of eosinophils in the expression of eotaxin gene upon the exposure to their survival and/or death factors.

Granulocyte macrophage colony-stimulating factor is the main cytokine enhancing survival of eosinophils in asthmatic airways

Interleukin (IL)-3, IL-5 and granulocyte macrophage colony-stimulating factor (GM-CSF) prolong the survival of eosinophils, which are conspicuous in asthmatic airways, but it is still controversial which one plays a major role in enhancing the survival of eosinophils in asthmatic airways. The role of these cytokines in airway eosinophilia was investigated using bronchoalveolar lavage (BAL) fluids from 11 symptomatic and nine asymptomatic patients with asthma and eight normal subjects. Eosinophil survival-enhancing activity (ESEA) was measured by a numerical change in viable eosinophils isolated from the peripheral blood of atopic patients and cultured with BAL fluids. ESEA was characterized by neutralization with antibodies to IL-3, IL-5 and/or GM-CSF. The differential count of BAL cells was achieved using Diff-Quik stain. T-cell subsets and activated T-cells were analysed by flow cytometry with dual stain using monoclonal antibodies to CD3, CD4, CD8 and CD25. ESEA was detected in eight of 11 BAL fluids of symptomatic asthma, but not in those of normal controls or asymptomatic asthmatics. In six symptomatic asthmatics, the mean percentage of inhibition in ESEA by anti-GM-CSF was higher than that of anti-IL-5 as well as anti-IL-3 (p<0.05). A mixture of antibodies to IL-3, IL-5 and GM-CSF totally inhibited the ESEA in four cases. The ESEA correlated with the percentage of eosinophils (p<0.05) and that of CD25(+)CD4 lymphocytes (p<0.05) of BAL cells. In conclusion, granulocyte macrophage colony-stimulating factor, rather than interleukin-3 or -5, is associated with eosinophil survival-enhancing activity inside the airways of symptomatic asthmatics. The activation of CD4 lymphocytes is related to the elevation of such activity.

The T cell receptor subsets of lymphocytes in bronchoalveolar lavage in patients with active pulmonary tuberculosis

STUDY OBJECTIVE

To determine whether or not the levels of gamma/delta lymphocytes increase in bronchoalveolar lavage (BAL) fluid from patients with pulmonary tuberculosis.

DESIGN

Prospective data collection relating to cells in BAL fluid and peripheral blood mononuclear cells (PBMC) from patients with pulmonary tuberculosis and control subjects.

SETTING

A university hospital, from March 1990 to December 1993.

PATIENTS

Thirteen patients with pulmonary tuberculosis who were diagnosed by culture of Mycobacterium tuberculosis from their sputum of BAL fluid and/or clinical response were enrolled in the study. Fifteen healthy volunteers participated as control subjects.

MEASUREMENTS AND RESULTS

The differential cell counts in BAL fluid were made by Diff-Quik stain. The percentages of T-cell receptor (TCR) (gamma/delta and alpha/beta)-positive lymphocytes and interleukin 2 (IL-2) receptor-positive CD3 lymphocytes in BAL fluid and peripheral blood were measured by dual scan with flow-cytometry. The percentage and absolute number of lymphocytes and the percentages of CD3+, IL2R+ lymphocytes in BAL fluid significantly increased in patients with tuberculosis when compared with those of control subjects. The percentages and numbers of gamma/delta and alpha/beta TCR-positive lymphocytes in BAL fluid and PBMC from patients with tuberculosis and indistinguishable from those of control subjects.

CONCLUSIONS

gamma/delta Lymphocytes do not appear to have as much meaning in patients as they do in animal studies.

A case of bronchiolitis obliterans organizing pneumonia associated with adenovirus

A 58-year-old man described a short history of dyspnea and a preceding flu like illness with roentgenographic features of an interstitial lung disease. An open lung biopsy specimen from him showed bronchiolitis obliterans with organizing pneumonia (BOOP). Adenovirus was isolated from a throat swab. There was both clinical and radiographic improvement with supportive care. We herein report a first case of BOOP associated with adenovirus in Korea.