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Postoperative rotator cuff retear after arthroscopic rotator cuff repair (ARCR) is still a major problem. Various risk factors such as age, gender, and tear size have been reported. Recently, magnetic resonance imaging-based stump classification was reported as an index of rotator cuff fragility. Although stump type 3 is reported to have a high retear rate, there are few reports on the risk of postoperative retear based on this classification. Machine learning (ML), an artificial intelligence technique, allows for more flexible predictive models than conventional statistical methods and has been applied to predict clinical outcomes. In this study, we used ML to predict postoperative retear risk after ARCR. The retrospective case-control study included 353 patients who underwent surgical treatment for complete rotator cuff tear using the suture-bridge technique. Patients who initially presented with retears and traumatic tears were excluded. In study participants, after the initial tear repair, rotator cuff retears were diagnosed by magnetic resonance imaging; Sugaya classification types IV and V were defined as re-tears. Age, gender, stump classification, tear size, Goutallier classification, presence of diabetes, and hyperlipidemia were used for ML parameters to predict the risk of retear. Using Python's Scikit-learn as an ML library, five different AI models (logistic regression, random forest, AdaBoost, CatBoost, LightGBM) were trained on the existing data, and the prediction models were applied to the test dataset. The performance of these ML models was measured by the area under the receiver operating characteristic curve. Additionally, key features affecting retear were evaluated. The area under the receiver operating characteristic curve for logistic regression was 0.78, random forest 0.82, AdaBoost 0.78, CatBoost 0.83, and LightGBM 0.87, respectively for each model. LightGBM showed the highest score. The important factors for model prediction were age, stump classification, and tear size. The ML classifier model predicted retears after ARCR with high accuracy, and the AI model showed that the most important characteristics affecting retears were age and imaging findings, including stump classification. This model may be able to predict postoperative rotator cuff retears based on clinical features. [ABSTRACT FROM AUTHOR]

A high postoperative retear rate after arthroscopic rotator cuff repair (ARCR) of large and massive tears remains a problem. This study evaluated rotator cuff integrity after ARCR with fascia lata graft augmentation for large and massive rotator cuff tears and compared clinical outcomes between patients with intact repairs and retears. Forty-five patients with rotator cuff tears who could not undergo primary repair due to tendon retraction underwent arthroscopic medialized single-row repair with fascia lata graft augmentation. The patients' minimum follow-up was 2 (2-9) years. Supraspinatus cuff integrity was evaluated postoperatively by magnetic resonance imaging. We compared the clinical outcomes of patients with intact repairs vs. retears based on the University of California–Los Angeles (UCLA), Constant, and Japanese Orthopaedic Association (JOA) scores. We also evaluated their range of motion (ROM) and muscle strength. Retears were observed in 11 of 45 patients. UCLA, Constant, and JOA scores significantly improved postoperatively compared to preoperatively in the intact repair (all P <.001) and retear (all P <.036) groups. The intact repair group had significantly higher Constant (75.6 [mean] ± 9.9 [SD] vs. 69.8 ± 7.9; P =.026) and JOA (94.4 ± 6.9 vs. 89.8 ± 5.9; P =.041) scores than the retear group. Forward elevation, abduction, and the strengths of abduction and external rotation significantly improved in the intact repair group (all P <.003) but not in the retear group (all P >.05). The intact repair group had significantly higher postoperative forward flexion (165° ± 15° vs. 154° ± 23°; P =.036), abduction (164° ± 17° vs. 151° ± 26°; P =.029), and abduction strength (3.5 ± 2.2 kg vs. 2.3 ± 1.2 kg; P =.017) than the retear group. In the intact repair group (n = 34), Sugaya type I:II ratio differed significantly between postoperative 3 months (2:32) and 24 months (24:10) (P <.001). Repaired tendon thickness did not decrease significantly between 3 months (7.1 mm) and 2 years (6.9 mm) (P =.543). ARCR with fascia lata graft augmentation of large and massive rotator cuff tears showed a 24.4% retear rate but significantly improved the clinical scores, ROMs, and muscle strength with excellent cuff integrity in the intact repair group. However, the differences in the Constant and UCLA scores between the intact repair and retear groups were under the minimal clinically important difference, and their clinical significance is uncertain. Our results confirm that ARCR with fascia lata graft augmentation improves patients' postoperative outcomes if the repair site is maintained postoperatively. [ABSTRACT FROM AUTHOR]

Retear after arthroscopic rotator cuff repair (ARCR) remains a complication of important concern. Few reports have evaluated retear timing and its associated patient characteristics in large cohorts. This study aimed to investigate retear timing and patient characteristics and factors associated with this parameter. Of the 638 consecutive shoulders that underwent ARCR from August 2009 to November 2019, shoulders with retear complication within 1 year of surgery were included. Retears were defined as type IV or V of the Sugaya's classification, and magnetic resonance imaging was performed at 6 weeks, 3 months, 6 months, and 1 year after surgery. The distribution of patients with retears at the timing of retears was investigated. In addition, patients with retears were classified into the following two groups: early group with retears occurring at 6 weeks and 3 months postoperatively or late group with retears occurring between 6 months and 1 year postoperatively. Associated factors such as sex, age, tear size, pre and postoperative range of motion, surgical technique, and clinical outcome between the two groups were investigated. The 41 shoulders with retears were divided into four groups: 1) within 6 weeks after surgery (n = 9, 22.0%), 2) 6 weeks-to 3 months after surgery (n = 19, 46.3%), 3) 3-6 months after surgery (n = 11, 26.8%), and 4) 6 months-1 year after surgery (n = 2, 4.9%). In addition, there were significantly larger retear sizes in the Sugaya's classification in the early group compared to the late group (P =.013), while there were significantly more males in the late group compared to the early group (P =.030). The highest retear rate after ARCR was observed from 6 weeks to 3 months after surgery, with equivalent rates within 6 weeks and from 3 months to 6 months after surgery. [ABSTRACT FROM AUTHOR]

Large and massive rotator cuff tears are challenging for surgeons because of postoperative complications such as repaired site retears. Recently, collagen extracted from fish scales has gained more attention because fish byproducts are considered a safer collagen source than other animal-derived scaffolds. This study aimed to evaluate the biological efficacy of tilapia scale–derived collagen scaffolds for rotator cuff repair in rat models. The infraspinatus tendon was resected from the greater tuberosity of Sprague-Dawley rats. In the control group, the tendon edge was sutured directly to the humeral head. In the augmentation group, the repaired site was augmented with a tilapia scale–derived collagen scaffold. Histologic examinations were performed at 2 and 4 weeks postoperatively via safranin O and immunofluorescence staining (isolectin B4 and type II collagen) in the bone-tendon junction. For mechanical analysis, the ultimate failure load of the tendon-humeral head complex was evaluated at 6 weeks postoperatively. During safranin O staining, the repaired enthesis demonstrated greater proteoglycan staining in the augmentation group than in the control group at 4 weeks postoperatively. Compared to controls, the augmentation group had significantly higher vascular staining with isolectin B4 at 2 and 4 weeks postoperatively, type II collagen expression at 4 weeks postoperatively, and ultimate failure load at 6 weeks postoperatively. Augmentation therapy using tilapia scale–derived type I collagen scaffolds promoted angiogenesis and fibrocartilage regeneration at the enthesis and provided higher mechanical strength than controls. [ABSTRACT FROM AUTHOR]

Recently, deep learning (DL) algorithms have been adapted for the diagnosis of medical images. The purpose of this study was to detect image features using DL without measuring median nerve cross-sectional area (CSA) in ultrasonography (US) images of carpal tunnel syndrome (CTS) and calculate the diagnostic accuracy from the confusion matrix obtained. US images of 50 hands without CTS and 50 hands diagnosed with CTS were used in this study. The short-axis image of the median nerve was visualized, and 5000 images of both groups were prepared. Forty hands in each group were used as training data for the DL algorithm, while the remainder were used as test data. Transfer learning was performed using three pre-trained models. The confusion matrix and receiver operating characteristic curves were used to evaluate diagnostic accuracy. Furthermore, regions where DL was determined to be important were visualized. The highest score had an accuracy of 0.96, precision of 0.99 and recall of 0.94. Visualization of the important features revealed that the DL models focused on the epineurium of the median nerve and the surrounding soft tissue. The proposed technique enables the accurate prediction of CTS without measurement of the CSA. [ABSTRACT FROM AUTHOR]

Purpose: To calculate the diagnostic accuracy from the confusion matrix using deep learning (DL) on ultrasound (US) images of Palmer 1B triangular fibrocartilage complex (TFCC) injury.Methods: Twenty-nine wrists of 15 healthy volunteers (11 men; mean age, 34.9 years ± 9.7) (control group) and 20 wrists of 17 patients (11 men; mean age 41.0 years ± 12.2) with TFCC injury (Palmer type IB) (injury group) were included in the study. The diagnosis of Palmer 1B TFCC injury was made using magnetic resonance imaging, computed tomography arthrography, and intraoperative arthroscopic findings. In total, 2,000 images were provided to each group, 80% of which were randomly selected by AI and used as training data; the remaining data were used as test data. Transfer learning was conducted using a pretrained 3 separate models (GoogLeNet, ResNet50, ResNet101). Model evaluation was performed using a confusion matrix. The area under a receiver operating characteristic curve was also calculated. The occlusion sensitivity was used to visualize the important features.Results: For the prediction of TFCC injury by the DL model, the best score of accuracy was 0.85 in GoogLeNet, a recall was 1.0 in ResNet50 and ResNet101, and a specificity was 0.78 in GoogLeNet. In predicting the TFCC injury for the test data, the best score of the AUC was 0.97 on ResNet101. Visualization of important features showed that AI predicted the presence of injury by focusing on the morphology of the articular disc.Conclusions: US images using the DL model predicted Palmer 1B TFCC injury with high accuracy, with the best scores of 0.85 for accuracy on GoogLeNet, 1.00 for sensitivity on ResNet50 and ResNet101, and 0.78 for specificity on GoogLeNet. The use of DL for US imaging of Palmer 1B TFCC injury predicted the injury as well as magnetic resonance imaging and computed tomography arthrography LEVEL OF EVIDENCE: IV; retrospective case series study. [ABSTRACT FROM AUTHOR]

Previous studies have reported that glenohumeral internal rotation deficit (GIRD) may increase the risk of throwing-shoulder injuries. The purpose of this study was to analyze the conditions of the throwing shoulder in professional baseball pitchers with GIRD by comparing with those in pitchers without GIRD. In total, 26 male professional baseball pitchers participated in this study. We evaluated passive range of motion (ROM) and isometric muscle strength at internal rotation (IR) and external rotation (ER) at 90° of abduction, as well as the muscle thickness of the supraspinatus (SSP) and infraspinatus (ISP) by ultrasound. The pitchers were divided into 2 groups: those who exhibited a loss of IR of ≥20° in the throwing shoulder (GIRD group) and those who did not (non-GIRD group). In the GIRD group, the total ROM deficit (throwing side – non-throwing side) (P <.001), the muscle thickness ratio (throwing to non-throwing) of the SSP and ISP (P =.017 and P =.014, respectively), and the muscle strength ratio (throwing to non-throwing) of ER (P =.028) were significantly lower than those in the non-GIRD group. In contrast, the muscle strength ratio (throwing to non-throwing) of IR was significantly higher in the GIRD group than in the non-GIRD group (P =.0064). We have shown that GIRD has significant correlations with several conditions, such as atrophy of the SSP and ISP, weakness of ER strength, enhancement of IR strength, limitation of total ROM, and throwing side, all of which could be important factors for throwing-shoulder injuries. [ABSTRACT FROM AUTHOR]

Arthroscopic repair is performed for fovea injuries of the triangular fibrocartilage complex (TFCC) when instability of the distal radioulnar joint results in pain, decreased grip strength, and mechanical symptoms. During TFCC repair, reconstruction of its attachment to the fovea is important. Nonabsorbent suture tapes have gained attention for ligament repair in the trapeziometacarpal joint, scapholunate ligament, and thumb metacarpophalangeal ligament. However, there are no reports of TFCC repair using suture tapes. We evaluated the early postoperative results of this approach. Participants underwent arthroscopic suture tape repair of foveal TFCC tears and were observed for more than 1 year. All repairs were performed using suture tapes and an outside-in technique with a bone tunnel from the ulnar shaft to the fovea. The postoperative complications, postoperative wrist range of motion, grip strength, and the Modified Mayo Score were evaluated. Arthroscopic repair with a suture tape was performed for 20 hands using the outside-in technique. The ranges of motion for the operated and nonoperated hands were comparable 1 year after surgery (pronation, 84° ± 4°; supination, 83° ± 4°). The mean grip strength improved from 65% ± 13% before surgery to 89% ± 9% after a year. The mean Modified Mayo Score improved from 58 ± 11 before surgery to 91 ± 8 after a year. Postoperative complications included abnormal sensation of the dorsal ulnar side in 2 hands. After using a suture tape to attach the TFCC to the fovea, satisfactory function was achieved in the early postoperative period with grip strength restoration. For the repair of foveal TFCC tears, attachment to the ulnar fovea is important, and repair by a suture tape may be useful. Therapeutic IV. [ABSTRACT FROM AUTHOR]

Limitations of shoulder range of motion (ROM) have been reported to be at high risk for shoulder disorders in baseball players. In this study, we assessed posterior shoulder muscle stiffness using shear wave elastography in baseball players with and without posterior shoulder tightness. In total, 21 college baseball players volunteered to participate in this study. Passive ROMs for shoulder abduction and horizontal adduction were measured using a goniometer. Subsequently, we divided all participants into 2 groups based on the differences between bilateral shoulder ROMs: STIFF+ and STIFF− groups. Thickness and elasticity of the posterior and inferior shoulder muscles were assessed using ultrasound. Shoulder abduction ROM on the throwing side was 114.5° ± 5.3° and 131.3° ± 5.7° in the STIFF+ and STIFF− groups, respectively, which was significantly different between the 2 groups (P =.023). Horizontal adduction ROM on the throwing side was 96.6° ± 4.9° and 110.9° ± 4.8° in the STIFF+ and STIFF− groups, respectively, which was also significantly different between the 2 groups (P =.014). The elasticity of infraspinatus and lower trapezius in the STIFF+ group was significantly greater than that in the STIFF− group (P =.018 and.033, respectively). In this study, we found that the elasticity of infraspinatus and lower trapezius in stiff shoulders was significantly greater than that in nonstiff shoulders, which indicated that the infraspinatus and lower trapezius could be the key muscles in posterior shoulder tightness. [ABSTRACT FROM AUTHOR]

Most rotator cuff tears are the result of age-related degenerative changes, but the mechanisms underlying these changes have not been reported. Recently, advanced glycation end products (AGEs) have been regarded as an important factor in senescence. Therefore, we hypothesized that AGEs would have detrimental effects on rotator cuff–derived cells. In this study, we investigated the influence of AGEs on rotator cuff–derived cells in vitro and ex vivo. Rotator cuff–derived cells were obtained from human supraspinatus tendons. The cells were cultured in the following media: (1) regular medium with 500 μg/mL AGEs (High-AGEs), (2) regular medium with 100 μg/mL AGEs (Low-AGEs), and (3) regular medium alone (Control). Cell viability, secretion of vascular endothelial growth factor, and the expressions of hypoxia-inducible factor-1α, reactive oxygen species, and apoptosis were assessed after cultivation. An ex vivo tissue culture with AGEs was also performed to measure the tensile strength. Cell viability in the High-AGEs group was significantly suppressed relative to that in the Controls. The amount of vascular endothelial growth factor secretion was significantly greater in the High- and Low-AGEs groups than in the Controls. Immunofluorescence stain demonstrated enhancement of hypoxia-inducible factor-1α and reactive oxygen species expressions and cell apoptosis in the High- and Low-AGEs groups relative to that in the Controls. In ex vivo mechanical testing, tensile strength was significantly higher in the Control group than in the AGEs groups. These results indicated that AGEs caused age-related degenerative rotator cuff changes. The reduction of AGEs might prevent rotator cuff senescence-related degeneration. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this study was to evaluate an application of poly(d,l-lactide-co-glycolide) (PLG) scaffold created by electrospinning in a rabbit rotator cuff defect model. Methods: Forty-two Japanese white rabbits were used in this study. Defects of the infraspinatus tendon were created, and the PLG scaffolds were implanted. Contralateral infraspinatus tendons were reattached without creating defects. Histologic analyses were performed 4, 8, and 16 weeks after the operation, and mechanical evaluations were performed 0, 4, 8, and 16 weeks after the operation. Results: Scaffold fibers remained without dissolution and spindle-shaped cells were observed inside of the scaffold at 4 weeks postoperatively. At 8 weeks, the PLG scaffold had dissolved and bone formation was observed at the scaffold-bone interface. At 16 weeks, the scaffold-bone interface matured and expression of type II collagen was observed. A statistical difference in ultimate failure load was not seen between the scaffold group and reattachment group or normal tendon after 8 weeks postoperatively. The stiffness in the scaffold group was not significantly different from that in the reattachment group at each time point. However, it was significantly weaker than normal tendon at each time point. Conclusions: Transplantation of cell-free PLG scaffold showed cell migration and type II collagen and proteoglycan expression at the scaffold-bone junction by 16 weeks postoperatively with a sufficient ultimate failure load in a rabbit rotator cuff defect model. Clinical Relevance: The PLG scaffold could be applied to bridge rotator cuff defects. The results showed that bridging with scaffold can be equivalent to reattachment. [Copyright &y& Elsevier]

Purpose: The purpose of our study was to explore the possibility that an electrospun bioabsorbable scaffold could be used in the treatment of a full-thickness articular defect without the addition of exogenous cells in a rabbit model. Methods: Two types of poly(D,L-lactide-co-glycolide) (PLG) scaffolds, a solid cylindrical type and a cannulated tubular type, were made with the electrospinning method. Osteochondral defects, 5 mm in diameter and 5 mm in depth, made on the femoral condyles of rabbits were filled with these scaffolds, and the repair process was investigated histologically. Results: In the groups in which the defect was filled with the scaffold, fibrous tissue at the articular surface of the scaffold was observed at postoperative week 2. Thereafter cartilage at the articular surface and bone at the subchondral zone were regenerated, and the repaired cartilage was maintained through postoperative week 24. By contrast, the untreated defect was filled with hematoma at postoperative week 2; thereafter regenerated cartilage and bone were observed. However, the surface of the articular cartilage was not regular, and regenerated cartilage was not well organized. The histologic scores of the groups in which the defect was filled with cannulated tubular electrospun PLG scaffolds were significantly higher than those of the untreated defect group at postoperative weeks 12 and 24 (P < .01). Conclusions: The electrospun PLG scaffold could repair a 5-mm osteochondral defect created in the rabbit model without exogenous cultured cells. Clinical Relevance: The electrospun PLG scaffold could repair full-thickness osteochondral defects. The cannulated type of PLG scaffold has the possibility to lead not only to good regeneration of cartilage but also to easy transplantation by use of a guidewire through the cannulas in the scaffold. [Copyright &y& Elsevier]

Excellent clinical results of arthroscopic repair of rotator cuff tears have been reported. However, retears after surgical repair of large and massive rotator cuff tears are one of the most common complications. We present single-row repair with graft augmentation of the fascia lata for large and massive rotator cuff tears to reduce tension at the tendon-bone repair site, and this technique may prevent retears of the repaired rotator cuff. A candidate for this technique is a patient who has a large or massive rotator cuff tear in which the torn edge cannot reach the footprint after mobilization of the torn rotator cuff. This technique could provide an excellent option for irreparable large and massive rotator cuff tears. [ABSTRACT FROM AUTHOR]