Automated detection and classification of the rotator cuff tear on plain shoulder radiograph using deep learning.

BACKGROUND: The diagnosis of rotator cuff tears (RCTs) using radiographs alone is clinically challenging; thus, the utility of deep learning algorithms based on convolutional neural networks has been remarkable in the field of medical imaging recognition. We aimed to evaluate the diagnostic performance of artificial intelligence (a deep learning algorithm; a convolutional neural network) to detect and classify RCTs using shoulder radiographs, and compare its diagnostic performance with that of orthopedic surgeons. METHODS: A total of 1169 plain shoulder anteroposterior radiographs (1 image per shoulder) were included in the total dataset and divided into four groups: intact, small, medium, and large to massive tear groups. The sensitivity, specificity, positive predictive value, negative predictive value, accuracy, and area under the receiver operating curve were measured for the detection of RCTs through binary classification. The average accuracy, recall, precision, and F1-score were divided into four groups by cuff tear size for multiclass classification. RESULTS: The convolutional neural network demonstrated a high performance, with 92% sensitivity, 69% specificity, 86% accuracy, and an area under the receiver operating curve of 0.88 for the detection of RCTs. The average accuracy, recall, precision, and F1-score of the convolutional neural network for classification were 60%, 0.42, 0.49, and 0.45, respectively. The accuracy of the convolutional neural network for the detection and classification of RCTs was significantly better than that of orthopedic surgeons. CONCLUSION: The convolutional neural network demonstrated the diagnostic ability to detect and classify RCTs using plain shoulder radiographs, and the diagnostic performance exhibited equal to superior accuracy when compared with those of shoulder experts.

Efficacy of radial shock wave therapy on rat models of adjuvant arthritis.

BACKGROUND: Extracorporeal shock wave therapy (ESWT) is an effective treatment for musculoskeletal pain, tendinopathy, and fasciitis with an anti-inflammatory effect. ESWT can be categorized into two groups: radial pressure wave (RPW) and focused shock wave (FSW). Although there have been several studies on the inflammation and pain-improvement mechanisms of FSW, there are few studies on the pain-improvement mechanisms of RPW. This study aimed to elucidate the efficacy of RPW in a rat model of adjuvant arthritis. METHODS: Ninety-six rats were randomly categorized into three groups: RPW, control, and sham as follows: (I) RPW group, which received RPW application after complete Freund's adjuvant (CFA) injection; (II) Control group, which received only CFA injection; and (III) Sham group, which received only saline injection. All rats were evaluated at 0, 4, 7, 14, 28, and 56 days post-RPW application based on foot circumference, von Frey test, and immunohistochemistry of nerve fibers for calcitonin gene-related peptide (CGRP) and protein gene product (PGP) 9.5 in plantar skins. RESULTS: There were no significant differences in foot circumference between the RPW and control groups at any time point. The RPW group showed significant improvements in the von Frey test results on days 7 and 14. The total CGRP-immunoreactive (ir) and PGP9.5-ir nerve fiber lengths in the RPW group decreased on day 0; however, both were increased in the control group. The CGRP-ir and PGP9.5-ir nerve fibers in the RPW group were significantly shorter than those in the control group until day 14 after RPW. CONCLUSIONS: RPW improved the mechanical hypersensitivity between days 7 and 14 after application. Like FSW, RPW also induced the degeneration of sensory nerve fibers in the skin in the early period after irradiation, and reinnervation occurred between 14 and 28 days. Thus, our results demonstrate one of the pain relief mechanisms after RPW application.

Biomechanical Comparison of Stability and Strength After Ulnar Collateral Ligament Reconstruction With Suture Anchor Fixation Versus Bone Tunnels.

Background: Ulnar collateral ligament (UCL) injuries occur frequently in baseball players, and UCL reconstruction is performed when nonoperative treatment fails. Purpose: To compare a novel all-suture anchor method of UCL reconstruction with a method using bone tunnels (Ito method) by investigating the displacement against valgus torque and the failure strength. Study Design: Controlled laboratory study. Methods: Eight fresh-frozen cadaveric upper extremities (mean age, 82.0 years) were utilized in this study. To evaluate the displacement against valgus torque, the valgus stability test was performed for 4 anterior oblique ligament (AOL) conditions: intact AOL, resected AOL, reconstructed using the anchor method, and reconstructed using the Ito method. The load-to-failure test was performed to evaluate the failure strength of the anchor and Ito methods. Displacement against valgus load was compared between conditions using the repeated-measures 2-way analysis of variance with Bonferroni post hoc test, and failure strength between the anchor and Ito methods was compared using the unpaired t test. Results: Displacements of the intact AOL and anchor method were significantly greater than those of the resected AOL at both 60° and 90° of flexion (intact AOL: P = .005 and P < .001, respectively; and anchor method: P = .024 and P < .001, respectively). The displacement of the Ito method at 90° of flexion was significantly greater than that of the resected AOL (P = .003), but no significant difference was observed at 60° of flexion (P = .109). There were no significant differences in displacement between the anchor and Ito methods at any flexion angle, nor was there a significant difference in failure torque between the anchor and Ito methods (16.3 ± 3.1 vs 17.6 ± 2.3 N·m, respectively; P = .537). Conclusion: The displacement and failure strength against a valgus load after UCL reconstruction using a suture anchor on the ulnar side were equal to those using bone tunnels. Clinical Relevance: UCL reconstruction using a suture anchor on the ulnar side is simpler and less invasive than using bone tunnels, with similar outcomes.

Postoperative complications of reverse total shoulder arthroplasty: a multicenter study in Japan.

Background: Reverse total shoulder arthroplasty (RSA) has been approved since 2014 in Japan, and the number of RSA cases has been accumulating. However, only short-to medium-term outcomes have been reported, with a small number of case series, because of its short history in Japan. This study aimed to evaluate complications after RSA in hospitals affiliated with our institute, with comparison to those in other countries. Methods: A multicenter retrospective study was performed at 6 hospitals. In total, 615 shoulders (mean age: 75.7 ± 6.2 years; mean follow-up: 45.2 ± 19.6 months) with at least 24 months of follow-up were included in this study. The active range of motion was assessed pre-and postoperatively. The 5-year survival rate was evaluated for reoperation for any reason in 137 shoulders with at least 5 years of follow-up using Kaplan-Meier analysis. Postoperative complications were evaluated, including dislocation; prosthesis failure; deep infection; periprosthetic, acromial, scapular spine, and clavicle fractures; neurological disorders; and reoperation. Furthermore, imaging assessments, including scapular notching, prosthesis aseptic loosening, and heterotopic ossification were evaluated on postoperative radiography at the final follow-up. Results: All range of motion parameters were significantly improved postoperatively (P < .001). The 5-year survival rate was 93.4% (95% confidence interval: 87.8%-96.5%) for reoperation. Complications occurred in 256 shoulders (42.0%), with reoperation in 45 (7.3%), acromial fracture in 24 (3.9%), neurological disorders in 17 (2.8%), deep infection in 16 (2.6%), periprosthetic fracture in 11 (1.8%), dislocation in 9 (1.5%), prosthesis failure in 9 (1.5%), clavicle fracture in 4 (0.7%), and scapular spine fracture in 2 (0.3%). Regarding imaging assessments, scapular notching was observed in 145 shoulders (23.6%), heterotopic ossification in 80 (13.0%), and prosthesis loosening in 13 (2.1%). Conclusion: This is the first large case series to investigate the complications after RSA in Japan, and the overall frequency of complications after RSA was similar to that in other countries.

Effect of arthroscopic subacromial decompression during arthroscopic repair of small to medium-sized rotator cuff tears.

Background: Although arthroscopic subacromial decompression (ASD) is a commonly used procedure during arthroscopic rotator cuff repair (ARCR), the effect of ASD on the clinical outcomes for ARCR is controversial. The purpose of this study was to compare the clinical outcomes of ARCR with or without ASD. Methods: Patients (n = 315 with 320 shoulders) who underwent ARCR for small to medium-sized rotator cuff tears were followed for at least 24 months. ARCR was performed with ASD (180 shoulders, group A) or without ASD (140 shoulders, group N). There were no significant differences in patient demographics, including mean age and mean follow-up time. Rotator cuff repair was performed using the suture-bridge technique in all shoulders, and all patients were treated using the same rehabilitation protocol after surgery. University of California at Los Angeles score, Constant score, re-tear rates, revision surgery rates, and operating time were compared between groups. Re-tear was defined as Sugaya classification Types 4 and 5 using postoperative magnetic resonance imaging at more than 12 months. Results: There was no statistically significant difference in clinical outcomes before and after ARCR between groups. However, the University of California at Los Angeles scores and Constant scores significantly improved in both groups after surgery (P < .001). Furthermore, there was no major difference in the re-tear rates between groups A (7/180 shoulders, 3.9%) and N (11/140 shoulders, 7.9%) (P = .146). Revision surgeries were performed on 3/180 shoulders (1.7%) in group A (due to postoperative deep infection in one shoulder and revision ARCR for re-tear in two shoulders). No revisions surgeries were needed in group N patients (P = .259). The mean surgical time for group A was 62.0 ± 27.0 minutes (29-138 min.) and 52.4 ± 26.1 minutes (17-124 min.) for group N (P = .007). Conclusion: These results suggest that ASD has a limited effect on clinical outcomes of ARCR for small to medium-sized rotator cuff tears.

Imaging and histological evaluation of the long head of the biceps tendon in the presence of different types of rotator cuff tears.

BACKGROUND: A comparison of changes in the long head of the biceps tendon for different types of rotator cuff tears has not been previously performed. Furthermore, the correlation between the thickening and degeneration of the long head of the biceps tendon and the cause of these changes have not been fully clarified. We evaluated the relationship between degenerative changes in the long head of the biceps tendon and rotator cuff tears in a rat model using imaging and histology. METHODS: Ninety-six 12-week-old Sprague-Dawley rats were divided into anterior (subscapularis tear), anterosuperior (subscapularis, supraspinatus, and infraspinatus tears), superior (supraspinatus and infraspinatus tears), and control groups. The long head of the biceps tendon was harvested at 4 or 12 weeks postoperatively. The cross-sectional areas of the intra- and extra-capsular components of the tendon were measured using micro-computed tomography, and the affected/normal ratio of the cross-sectional area was calculated. Masson's trichrome staining and Alcian blue staining were performed for histologic analysis, with degenerative changes described using the modified Bonar scale. The correlation between the affected/normal ratio and Bonar scores was evaluated. RESULTS: The affected/normal ratio was higher for the anterior and anterosuperior groups than for the control group at 4 and 12 weeks. The ratio increased for the intra-articular portion in the superior group and for both the intra- and extra-articular portions in the anterior and anterosuperior groups. Degeneration considerably progressed in the anterior and anterosuperior groups compared with the control group from weeks 4 to 12 and was greater in the intra- than in the extra-articular portion. The ratio correlated with extracellular matrix score. CONCLUSIONS: Subscapularis tears were associated with progressive thickening and degeneration of the long head of the biceps tendon at 4 and 12 weeks postoperatively, which was more significant in the intra- than in the extra-articular portion. Histologic evaluation indicated that the extracellular matrix likely caused these degenerative changes.

Evaluation of articular changes using a rat mono-iodoacetate-induced shoulder arthritis model by histology and radiology.

The rat mono-iodoacetate (MIA) arthritis model has been used in studies on the hip, knee, and ankle joints. Few studies have explored its utility in shoulder arthritis research, and none have evaluated the effects of time and different MIA doses on arthritis progression. Therefore, we developed a rat MIA shoulder arthritis model to evaluate articular changes through radiological and histological analyses. Sprague-Dawley rats (n = 108) were equally divided into groups that were intra-articularly injected with 0.5 mg of MIA (in 50 µL of purified water), 2.0 mg of MIA (in 50 µL of purified water), or purified water (50 µL; sham group). Throughout the study period, 18 rats (six per group) were evaluated by computed tomography and assessed using the Larsen's classification system; 90 rats were further evaluated histologically using the Osteoarthritis Research Society International scoring system. Computed tomography revealed that the groups injected with MIA developed arthritis and osteophytes 14 days after injection, which progressed temporally. The Larsen's grades worsened over time; at all time points, the scores were higher in the group injected with 2.0 mg of MIA than in the group injected with 0.5 mg of MIA. Furthermore, concurrent with the worsening Larsen's grades, the Osteoarthritis Research Society International scores also significantly increased over time; at all time points, they were higher in the group injected with 2.0 mg of MIA than in the group injected with 0.5 mg of MIA. Our rat MIA shoulder arthritis model revealed radiologically and histologically confirmed temporal and MIA dose-dependent arthritic changes.

Return to sports and physical work after anatomical and reverse shoulder arthroplasty.

BACKGROUND: No consensus has been reached on the return to sports or physical work after shoulder arthroplasty due to a shortage of literature. The purpose of this study was to investigate return to sports or physical work after anatomical total shoulder arthroplasty (aTSA) and reverse shoulder arthroplasty (RSA), as well as the clinical and radiographic outcomes. METHODS: The inclusion criteria were as follows: 1) aTSA or RSA between 2012 and 2017, and 2) patients who preoperatively participated in sports or physical work. The exclusion criteria were as follows: 1) revision arthroplasty, 2) fracture/dislocation, 3) fracture sequelae, 4) postinfection, and 5) <2-year follow-up. Sports and physical work were classified as low-, medium-, or high-load activities. Range of motion, Constant score, sport or work return, and radiographic findings were evaluated and compared between aTSA and RSA groups. RESULTS: The subjects who met the criteria were 90 shoulders in 86 patients. The aTSA group consisted of 30 shoulders (10 men and 20 women) with a mean age of 71 ± 8 years (range, 56-85). The RSA group consisted of 60 shoulders (39 men and 21 women) with a mean age of 72 ± 6 years (range, 56-83). Active range of motion significantly improved after surgery in all directions in the aTSA group but only in flexion and external rotation in the RSA group. Postoperative external and internal rotations, as well as postoperative Constant scores and satisfaction, were significantly better in the aTSA than in the RSA group. In the aTSA group, the return rate was 93%, and the complete return rate was 70%. In the RSA group, the return rate was 83%, and the complete return rate was 30%. The complete return rate was significantly higher in the aTSA than in the RSA group. Only one aTSA shoulder showed loosening of the glenoid implant, and 8 RSA shoulders demonstrated low-grade scapular notching. CONCLUSION: The return to sports or physical work rates after aTSA and RSA were high; however, the complete return rates were significantly higher in the aTSA group than in the RSA group. No radiographic failures were identified except for one asymptomatic glenoid loosening with a midterm follow-up.

Clinical outcomes of anatomic total shoulder arthroplasty for primary shoulder osteoarthritis did not differ between elderly and younger Japanese patients.

Background: Few studies on the outcomes of anatomic total shoulder arthroplasty (aTSA) in Asian populations have been reported. In addition, approximately one-third of primary aTSA were performed for patients 80 years or older in Japan, but the indication of aTSA for the primary shoulder osteoarthritis in the elderly population remained unclear. The purposes of this study were (1) to investigate clinical outcomes of aTSA in Japanese patients with primary glenohumeral osteoarthritis and (2) to compare clinical outcomes between patients 80 years or older and 70 years or younger. We hypothesized that aTSA would yield favorable outcomes in Japanese patients and that the outcomes of aTSA in patients 80 years or older would be comparable to those 70 years or younger. Methods: Patient records were retrospectively reviewed to collect patients who underwent aTSA for glenohumeral osteoarthritis between August 2011 and September 2017. The inclusion criterion of this study was aTSA performed for glenohumeral osteoarthritis. Exclusion criteria were as follows: (1) secondary osteoarthritis, (2) revision surgery, and (3) < 24-month follow-up. Range of motion (ROM) and Constant score were evaluated, and complications were investigated. Rotator cuff integrity was assessed by ultrasonography. We compared the outcomes between patients 80 years or older and 70 years or younger. Results: Seventy-seven shoulders (72 patients) met the study criteria. There were 14 men and 58 women with a mean age of 75 years (range, 57-93 years) at the time of surgery. The mean follow-up was 40 months (range, 24-84 months). The Constant score significantly improved from preoperative 54 (range, 35-78) to postoperative 89 (range 69-100, P = .03). Range of motion also showed significant improvement after surgery: flexion, 90° (range, 60°-130°) to 140° (range, 90°-170°); external rotation at the side, from 7° (range, -10 to 60°) to 40° (range, 5°-70°); internal rotation, from buttock (range, buttock-L3) to L2 level (range, buttock-T8) (P <.001 for all). Postoperative subscapularis tendon tears were detected in 3 shoulders (5%). Complications other than rotator cuff tears were observed in 5 shoulders (6%). Postoperative Constant score and ROM significantly improved in both elderly and younger patients without significant differences. Conclusion: The clinical outcomes after aTSA in the Japanese population demonstrated significant improvements in ROM and Constant score with a low complication rate in the mid-term follow-up. aTSA should be indicated even in elderly patients because they also demonstrated comparable outcomes to younger patients.

Influence of different energy patterns on efficacy of radial shock wave therapy.

BACKGROUND: One of the mechanisms of the efficacy of extracorporeal shock wave therapy (ESWT) for impaired muscle coordination of limbs is the destruction of Acetylcholine receptors (AChRs) at neuromuscular junction. The highly increased density of AChRs can change the acoustic impedance, and this change of the acoustic impedance can be the reason that radial shock wave (rESW) destroy AChRs selectively. However, the relationship between applied energy of rESWs and the therapeutic efficacy remains unclear, although some studies compared the clinical efficacy of rESWT between high- and low-energy applications. This study aimed to compare the CMAP change among different energy and pulses of rESW application. METHODS: Male Sprauger-Dawley rats were used. A device that generates radial shock waves pneumatically, was used to apply the following six patterns of radial extracorporeal shockwaves in different energy flux densities and pulses to the right calf of each rat: 1, 8000 pulses at 0.045 mJ/mm2; 2, 4000 pulses at 0.09 mJ/mm2; 3, 2000 pulses at 0.18 mJ/mm2; 4, 4000 pulses at 0.045 mJ/mm2; 5, 2000 pulses at 0.09 mJ/mm2; 6, 1000 pulses at 0.18 mJ/mm2. Left calf muscles were considered controls. RESULTS: There was a significant reduction in CMAP amplitude between control and rESW-exposed muscles in the group applied 4000 pulses with EFD at 0.09 mJ/mm2 and the group applied 2000 pulses with EFD at 0.18 mJ/mm2. However, the group applied 8000 pulses with EFD at 0.045 mJ/mm2 and all groups which was exposed to total 180 mJ rESW application did not show a significantly decreased CMAP amplitude compared with the untreated side. CONCLUSIONS: Total energy and energy flux density correlate with a decrease in CMAP amplitude by rESW application. These findings could be availed by clinicians in actual clinical setting for the proper application of rESW.

Return to Sport After Arthroscopic Rotator Cuff Repair in Middle-Aged and Elderly Swimmers.

BACKGROUND: No reports have been published on the clinical outcomes, including return to sport, after rotator cuff repair in middle-aged and elderly swimmers with rotator cuff tears. PURPOSE: To retrospectively investigate clinical outcomes and return to sport after arthroscopic rotator cuff repair in middle-aged and elderly swimmers. STUDY DESIGN: Case series; Level of evidence, 4. METHODS: Patients who underwent arthroscopic rotator cuff repair and met the following criteria were included: (1) age older than 45 years, (2) rotator cuff tears confirmed during surgery, (3) arthroscopic suture bridge rotator cuff repair, (4) primary surgery, and (5) swam more than once a week before surgery. The exclusion criteria were as follows: (1) irreparable large and massive tears, (2) shoulder instability, (3) arthritis or rheumatic disorders, or (4) less than 2-year follow-up. We investigated functional outcomes including range of motion; the University of California, Los Angeles (UCLA) score; the American Shoulder and Elbow Surgeons (ASES) score; return to swimming; and the return rates for each style of swimming. In addition, the functional outcomes and findings of magnetic resonance imaging were compared between the group with complete return and the group with incomplete or failed return. RESULTS: A total of 32 shoulders in 31 middle-aged and elderly swimmers (5 males, 26 females) were included. The mean age was 65 years (range, 47-78 years), and the mean follow-up was 47 months (range, 24-86 months). Return to swimming was achieved in 31 (97%) shoulders at a mean of 8 months (range, 3-24 months), and complete return was achieved in 18 (56%) shoulders at a mean of 12 months (range, 3-24 months). The return rate was 97% for freestyle, 83% for breaststroke, 74% for backstroke, and 44% for butterfly stroke. Postoperative UCLA and ASES scores were significantly higher in the group with complete return than in the group with incomplete or failed return (P = .001 and .01, respectively). Postoperative forward elevation was significantly better in the complete return group (P = .01). CONCLUSION: This study demonstrated that 97% of elderly swimmers who underwent arthroscopic rotator cuff repair could return to swimming. The complete return rate was 56%; however, the group with incomplete or failed return showed poorer active forward elevation. Freestyle had the highest complete return rate, whereas the butterfly stroke had the lowest return rate. It may be important to achieve good active forward elevation postoperatively to return to swimming.

Influence of a nerve injury proximal to the suprascapular nerve on healing of repaired rotator cuff tear.

BACKGROUND: Massive rotator cuff tears have a high rate of re-injury because of severe fatty infiltration. Our data showed that injuries proximal to the suprascapular nerve may be one cause of massive rotator cuff tears. The purpose of this study was to evaluate, using a rat model, how brachial plexus injury associated with a massive rotator cuff tear influences healing of the rotator cuff repair. METHODS: Seventy Sprague-Dawley rats were divided into three groups: rotator cuff tear with BP injury (DT group) (n = 28), rotator cuff tear without brachial plexus injury (T group) (n = 28), and a sham-operated group (n = 14). In the DT group, the rotator cuff tear was made and repaired 4 weeks after brachial plexus ligation. The gross assessment (evaluated the wet weight), biomechanical testing (evaluated the yield stress and the Young's modulus) and histological analyses (using the Bonar scale) were performed at baseline in the sham group, and at 4 and 12 weeks postoperatively in the DT and T groups (n = 7/group/time). RESULTS: Mean wet weight and yield stress were significantly lower in the DT group than in the T group. Additionally, the mean Young's modulus was significantly higher in the DT group than in the T group. Histologically, greater tendon degeneration was observed around the musculotendinous junction in the DT group than in the T group. CONCLUSION: The gross, biomechanical and histological data show that the repaired rotator cuff tendon with brachial plexus injury in rats does not heal as well as a repaired tendon without an accompanying brachial plexus injury. This suggests that more proximal neuropathy is one risk factor for re-tear of a repaired rotator cuff tendon.

Clinical application of intraoperative O-arm navigation in reverse shoulder arthroplasty.

BACKGROUND: Inaccurate fixation and positioning of the glenoid component using conventional techniques are problematic in reversed shoulder arthroplasty (RSA). Our objective was to investigate the accuracy of O-arm navigation of the glenoid component in RSA. METHODS: This retrospective case-control study comprised 2 groups of 25 patients who underwent reversed shoulder arthroplasty with or without intraoperative O-arm navigation. The intraoperative goal was to place the component neutrally in the glenoid in the axial plane and 10° inferiorly tilted in the scapular plane. Glenoid version angle and inclination were measured by computed tomography obtained preoperatively and a year postoperatively. Operative time, intraoperative bleeding, and the presence of postoperative complications were recorded. RESULTS: Compared with the ideal, the range of error for version was 7.3° (SD 3.6°) in the control group and 5.6° (SD 3.6°) in the navigated group (P = 0.278), and the range of error for inclination was 18.3° (SD 11.7°) in the control group and 4.9° (SD 3.8°) in the navigated group (P = 0.0004). The mean operative time was 164.6 (SD 21.2) min in the control group and 192.0 (SD 16.2) min in the navigated group (P = 0.001). The mean intraoperative bleeding was 201.0 (SD 37.0) mL in the control group and 185.3 (SD 35.6) mL in the navigated group (P = 0.300). There were no complications reported related to the intraoperative O-arm navigation. CONCLUSION: O-arm navigation may be a useful tool for the placement with inferior tilt of the glenoid procedure in reversed shoulder arthroplasty.

Arthroscopic tenodesis using a bioabsorbable interference screw and soft anchor: A case series of 60 patients.

BACKGROUND: Various arthroscopic tenodesis techniques for the treatment of long head of the biceps tendon pathologic abnormalities have been described. PURPOSE: This study evaluated the clinical outcomes of using a bioabsorbable interference screw and soft anchor for long head of the biceps tendon arthroscopic tenodesis. METHODS: Sixty patients treated by this technique between February 2013 and March 2015 were followed up for at least 2 years. In our operative technique, after the bone hole was made just proximal to the pectoralis major, the soft anchor was inserted at the bottom of the hole. After tenotomy of the long head of the biceps tendon proximal to the bone hole, the tendon was fixed into the bottom of the hole temporarily using the soft anchor. Finally, the tendon was fixed in the hole with a bioabsorbable interference screw. RESULTS: The UCLA score 15.1 points preoperatively and 32.4 points at follow-up (p < 0.05). The Constant 55.8 points preoperatively and 93.9 points at follow-up (p < 0.01). After biceps tenodesis, no cosmetic deformities were found in 56 patients (93.3%), and four patients (6.7%) had a Popeye deformity. On postoperative magnetic resonance evaluation, the long head of the biceps tendon was located on the bicipital groove without deviation in 53 cases (88.3%), on the bicipital groove with a partial deviation in 6 cases (10.0%), and outside the bicipital groove with complete deviation (dislocated) in 1 case (1.7%). CONCLUSION: We found that arthroscopic biceps tenodesis using a soft anchor provided a reliable means for treating biceps pathology with no cosmetic deformities and with good clinical results.

Comparison of glenohumeral joint rotation between asymptomatic subjects and patients with subacromial impingement syndrome using cine-magnetic resonance imaging: a cross-sectional study.

BACKGROUND: The purpose of this study to compare glenohumeral joint motion during active shoulder axial rotation between subacromial impingement syndrome (SIS) shoulders and asymptomatic shoulders using cine-magnetic resonance imaging (cine-MRI). Measurement of glenohumeral joint motion via manual intervention does not assess the usual glenohumeral joint motion, and the glenoid surface cannot be confirmed manually. However, cine-MRI can produce clear images of glenohumeral joint rotation. Therefore, we sought to measure the active ROM of the glenohumeral rotation using cine-MRI. METHODS: Seventy-three shoulders in 42 asymptomatic volunteers and 110 SIS shoulders in 103 consecutive patients were included in this study. We evaluated 36 matched pairs (72 shoulders in total) adjusting for baseline characteristics with propensity score matching method. The patients underwent cine-MRI during axial rotation of the adducted arm. During imaging, participants rotated their shoulder from the maximum internal rotation to the maximum external rotation over the first 10 s and then back to the maximum internal rotation over the subsequent 10 s. We assessed internal/external rotation, and compared the asymptomatic and SIS shoulders in this regard. Evaluation of rotation angles was performed on a series of axial images through the humeral head center. RESULTS: The mean internal rotation angles of the asymptomatic and patient groups were 55° ± 10° and 41° ± 23°, respectively, (P = .002; 95% Confidence Interval [CI], 51-58 vs 33-49); the mean external rotation angles were 47° ± 15° and 21° ± 25°, respectively, (P < .001; CI, 42-52 vs 13-29). CONCLUSIONS: Compared to asymptomatic shoulders, SIS shoulders showed significantly restricted glenohumeral rotation as determined by cine-MRI. Our results suggested that the significant limitation of active glenohumeral rotation might be associated with rotator cuff dysfunction.

Histological analysis and biomechanical evaluation of fatty infiltration after rotator cuff tear and suprascapular nerve injury in a rat model.

BACKGROUND: Rotator cuff tears are the most common shoulder injury, and little is known about the underlying etiology of fatty infiltration after rotator cuff tear. Previous studies speculated that rotator cuff tears lead to neural injury due to tethering of the suprascapular nerve at the notch. This study aimed to evaluate fatty infiltration after suprascapular nerve injury and rotator cuff tears. METHODS: Ninety adult male Sprague-Dawley rats were used and were divided into four groups: sham, tendon transection only, suprascapular nerve ligation, and tendon transection plus suprascapular nerve ligation. The suprascapular nerve injury models were created by tying the suprascapular nerve. At 2, 4, and 8 weeks postoperatively, histological analysis and biomechanical testing were performed to evaluate fatty infiltration and elastic change in the supraspinatus muscles. RESULTS: The amount of fatty infiltration in the supraspinatus muscle was significantly higher in both the suprascapular nerve ligation and tendon transection plus suprascapular nerve ligation groups than in the tendon transection only group at 2, 4, and 8 weeks. The ultimate failure load and tensile strength were significantly different among the tendon transection only, suprascapular nerve ligation, and tendon transection plus suprascapular nerve ligation groups at 8 weeks postoperatively. Furthermore, the mean Young's modulus of the muscle was significantly greater in the tendon transection plus suprascapular nerve ligation group than in both the tendon transection only and suprascapular nerve ligation groups at 8 weeks postoperatively. CONCLUSIONS: In this study, based on the results of histological and biomechanical examinations in our rat models, the etiology of fatty infiltration after massive rotator cuff tear might be different from the suprascapular nerve injury.

Relationship between neuropathy proximal to the suprascapular nerve and rotator cuff tear in a rodent model.

BACKGROUND: Rotator cuff tears are believed to coexist with cervical spine lesions. In cases of preexisting neuropathy, such as cervical spine lesions, fatty degeneration has likely already occurred due to the neuropathy. In these cases, rotator cuff tear is thought to occur easily because of preexisting extensive fatty degeneration and degeneration of the tendons due to neuropathy. This study aimed to evaluate the effects of paralysis due to neuropathy proximal to the suprascapular nerve on the supraspinatus and infraspinatus tendons using a rat model of brachial plexus paralysis. METHODS: This study included fifteen, 8-week-old Sprague-Dawley rats. The left shoulder was included in the paralysis group and the contralateral shoulder constituted the sham group. Biomechanical testing (evaluated maximum tear force, maximum displacement and Young's modulus) (n = 10) and histological analyses (n = 5) (using the Bonar scale) were performed at 12 weeks postoperatively to confirm the degeneration of the tendon. RESULTS: The mean maximum tear force was significantly lower in the paralysis group than in the sham group (P = 0.008), indicating that rotator cuff tears occurred with a lower force in the paralysis group. Additionally, the average Young's modulus was significantly greater in the paralysis group than in the sham group (P = 0.003), indicating that the rotator cuff muscle became hard and inflexible in the paralysis group. The Bonar scales of the histological analyses were significantly higher in the paralysis group (total score = 7.04 ± 0.61) than the sham group (total score = 0) (p < 0.0001). CONCLUSIONS: If neuropathy of proximal to the suprascapular nerve, such as cervical spine or brachial plexus lesion, exists, weakness and degeneration of the rotator cuff tendon and stiffness of the rotator cuff muscle develop. Neuropathy is likely a cause of rotator cuff tears.

Extracorporeal shock wave treatment can selectively destroy end plates in neuromuscular junctions.

INTRODUCTION: This study assesses the effect of radial extracorporeal shock wave (rESW) exposure on neuromuscular transmission and neuromuscular junction (NMJ) morphology. METHODS: We applied 2,000 rESWs at 0.18 mJ/mm2 and a frequency of 15 Hz to the right calf of male rats, measured the compound muscle action potential (CMAP), and examined NMJ morphology using electron microscopy. Left calf muscles were used as controls. RESULTS: rESW exposure significantly reduced CMAP amplitude without delayed latency in exposed muscles compared with controls. All rESW-exposed muscles exhibited NMJs with irregular end plates. Mean interjunctional fold interval was significantly increased compared with controls. However, axon terminals and muscle fibers surrounding NMJs with irregular end plates were unchanged. DISCUSSION: This localized destruction of end plates may be caused by differences in acoustic impedance induced by the density of acetylcholine receptors. These results provide a possible mechanism for the effectiveness of rESW treatment for spasticity and dystonia. Muscle Nerve 57: 466-472, 2018.

Radiographic evaluation of indirect decompression of mini-open anterior retroperitoneal lumbar interbody fusion: oblique lateral interbody fusion for degenerated lumbar spondylolisthesis.

PURPOSE: Extreme lateral interbody fusion provides minimally invasive treatment of spinal deformity, but complications including nerve and psoas muscle injury have been noted. To avoid nerve injury, mini-open anterior retroperitoneal lumbar interbody fusion methods using an approach between the aorta and psoas, such as oblique lumbar interbody fusion (OLIF) have been applied. OLIF with percutaneous pedicle screws without posterior decompression can indirectly decompress the spinal canal in lumbar degenerated spondylolisthesis. In the current study, we examined the radiographic and clinical efficacy of OLIF for lumbar degenerated spondylolisthesis. METHODS: We assessed 20 patients with lumbar degenerated spondylolisthesis who underwent OLIF and percutaneous pedicle screw fixation without posterior laminectomy. MR and CT images and clinical symptoms were evaluated before and 6 months after surgery. Cross sections of the spinal canal were evaluated with MRI, and disk height, cross-sectional areas of intervertebral foramina, and degree of upper vertebral slip were evaluated with CT. Clinical symptoms including low back pain, leg pain, and lower extremity numbness were evaluated using a visual analog scale and the Oswestry Disability Index before and 6 months after surgery. RESULTS: After surgery, significant increases in axial and sagittal spinal canal diameter (12 and 32 %), spinal canal area (19 %), disk height (61 %), and intervertebral foramen areas (21 % on the right side, 39 % on the left), and significant decrease of upper vertebral slip (-9 %) were found (P < 0.05). Low back pain, leg pain, and lower extremity numbness were significantly reduced compared with before surgery (P < 0.05). CONCLUSIONS: Significant improvements in disk height and spinal canal area were found after surgery. Bulging of disks was reduced through correction, and stretching the yellow ligament may have decompressed the spinal canal. Lumbar anterolateral fusion without laminectomy may be useful for lumbar spondylolisthesis with back and leg symptoms.