BACKGROUND: The pathogenesis of shoulder impingement syndrome (SIS) is still unclear, and its questionable causal relationship with rotator cuff (RC) injury has led to confusion in treatment. The purpose of this study was to explore the bidirectional causal relationship between SIS and RC injury.
METHODS: SIS and RC injury datasets downloaded from the IEU Open GWAS project and GWAS catalog databases. Inverse variance weighted (IVW), MR Egger, Weighted median, and Weighted mode were used in this Mendelian randomization (MR) analysis. Cochran\'s Q test, leave-one-out, and funnel plot method were used to evaluate heterogeneity between single nucleotide polymorphisms (SNPs). MR-Egger regression was used to test the horizontal pleiotropy of this study.
RESULTS: The IVW method (OR = 1.189, P = 0.0059) suggest the putative causal effect of RC injury on SIS. The results of MR Egger method (OR = 1.236, P = 0.2013), weighted median method (OR = 1.097, P = 0.2428) and weighted mode method (OR = 1.013, P = 0.930) showed no statistically significant (OR = 1.069071, P = 0.6173). Heterogeneity test and horizontal pleiotropy analysis suggested that there was no significant heterogeneity and horizontal pleiotropy in the results of this MR analysis. The reverse MR analysis showed heterogeneity, and the conclusion needs to be further explored.
CONCLUSIONS: The results of MR analysis support that RC injury may be causally associated with SIS.

BACKGROUND: Arthroscopic tuberoplasty is an optional technique for managing irreparable rotator cuff tears. However, there is a lack of studies investigating the resistance force during shoulder abduction in cases of irreparable rotator cuff tears and tuberoplasty.
OBJECTIVE: In shoulders with irreparable rotator cuff tears, impingement between the greater tuberosity (GT) and acromion increases the resistance force during dynamic shoulder abduction. Tuberoplasty is hypothesized to reduce this resistance force by mitigating impingement.
METHODS: Controlled laboratory study.
METHODS: Eight cadaveric shoulders, with a mean age of 67.75 years (range, 63-72 years), were utilized. The testing sequence included intact rotator cuff condition, irreparable rotator cuff tears (IRCTs), burnishing tuberoplasty, and prosthesis tuberoplasty. Burnishing tuberoplasty refers to the process wherein osteophytes on the GT are removed using a bur, and the GT is subsequently trimmed to create a rounded surface that maintains continuity with the humeral head. Deltoid forces and actuator distances were recorded. The relationship between deltoid forces and actuator distance was graphically represented in an ascending curve. Data were collected at five points within each motion cycle, corresponding to actuator distances of 20 mm, 30 mm, 40 mm, 50 mm, and 60 mm.
RESULTS: In the intact rotator cuff condition, resistance forces at the five points were 34.25 ± 7.73 N, 53.75 ± 7.44 N, 82.50 ± 14.88 N, 136.25 ± 30.21 N, and 203.75 ± 30.68 N. In the IRCT testing cycle, resistance forces were 46.13 ± 7.72 N, 63.75 ± 10.61 N, 101.25 ± 9.91 N, 152.5 ± 21.21 N, and 231.25 ± 40.16 N. Burnishing tuberoplasty resulted in resistance forces of 32.25 ± 3.54 N, 51.25 ± 3.54 N, 75.00 ± 10.69 N, 115.00 ± 10.69 N, and 183.75 ± 25.04 N. Prosthesis tuberoplasty showed resistance forces of 29.88 ± 1.55 N, 49.88 ± 1.36 N, 73.75 ± 7.44 N, 112.50 ± 7.07 N, and 182.50 ± 19.09 N. Both forms of tuberoplasty significantly reduced resistance force compared to IRCTs. Prosthesis tuberoplasty further decreased resistance force due to a smooth surface, although the difference was not significant compared to burnishing tuberoplasty.
CONCLUSIONS: Tuberoplasty effectively reduces resistance force during dynamic shoulder abduction in irreparable rotator cuff tears. Prosthesis tuberoplasty does not offer a significant advantage over burnishing tuberoplasty in reducing resistance force.
CONCLUSIONS: Tuberoplasty has the potential to decrease impingement, subsequently reducing resistance force during dynamic shoulder abduction, which may be beneficial in addressing conditions like pseudoparalysis.

BACKGROUND: Subacromial spurs are considered the one of the pathology underlying shoulder impingement syndrome. Furthermore, few studies have focused on the morphology of the subacromial spurs in normal Chinese people. This study aimed to study the spur distribution and to illustrate the morphology of spurs, which may help guide the extent of acromioplasty.
METHODS: A total of 93 normal individuals were enrolled, and both shoulders of all enrolled individuals were analyzed. The subjects were divided and classified into three different groups by ages: group I = 18-40 years, group II = 41-60 years, and group III ≥ 61 years. The osteophyte distribution, osteophyte area, subacromial surface area and osteophyte area/subacromial surface area ratio were measured and illustrated using Mimics and 3-matic software. The shape of the acromion was classified according to the Bigliani and Morrison classification system. The acromial angle was also classified. Then, the relationship between osteophytes, acromial classification and acromial angle was analyzed.
RESULTS: Type II (curved shape) was the most common type of acromion, and the hooked shape was a rare form. A significant increase in the left subacromial surface area in males was observed in group III compared with group I (P < 0.001) and group II (P = 0.004). The total spur/subacromial area ratio was significantly higher in group II than I. An obvious increase in the right subacromial area was observed in group III compared with group I (P = 0.004). Furthermore, there was a significant increase in the right spur area (P = 0.021) and total spur/subacromial area ratio (P = 0.006) in females in group II compared with group I. Fewer spurs were observed on the left than on the right side (p = 0.0482). One spur was most common among type II acromions (29/36) (80.56%) on the left side and the right side (34/52, 65.38%).
CONCLUSIONS: Spurs osteophytes are mainly distributed with an irregular shape and mostly run through the medial and lateral sides of the subacromial surface in normal subjects. The characteristics of subacromial spurs are so diverse that a surgeon must conduct subacromial decompression completely based on the morphology of individual spurs.

BACKGROUND: Emerging evidence has indicated the associations between subacromial impingement syndrome (SIS) of shoulder and lifestyle factors. However, whether unhealthy lifestyle factors causally increase SIS risk is not determined. This study aims to evaluate whether lifestyle factors are the risk factors of SIS.
METHODS: A two-sample Mendelian randomization (MR) study was designed to evaluate the effect of 11 lifestyle factors on SIS risk. Causality was determined using the inverse-variance weighted method to calculate the odds ratio (OR) and establish a 95% confidence interval (CI). Weighted median method, MR-Egger method and MR-PRESSO method were conducted as sensitivity analysis.
RESULTS: Four lifestyle factors were identified causally associated with an increased risk of SIS using the IVW method: insomnia (OR: 1.66 95% CI 1.38, 2.00; P = 8.86 × 10- 8), short sleep duration (OR: 1.53 95% CI 1.14, 2.05: P = 0.0043), mobile phone usage (OR: 4.65, 95% CI 1.59, 13.64; P = 0.0051), and heavy manual or physical work (OR: 4.24, 95% CI 2.17, 8.26; P = 2.20 × 10- 5). Another causal but weak association was found between smoking initiation on SIS (OR: 1.17, 95% CI 1.01, 1.35; P = 3.50 × 10- 2). Alcohol, coffee consumption, physical activity, sedentary behavior, sleep duration and computer usage were not found to be causally associated with an increased risk of SIS. Sensitivity analyses indicated that the MR estimates were robust and no heterogeneity and pleiotropy were identified in these MR analyses.
CONCLUSIONS: Sleep habits and shoulder usage were identified as causal factors for SIS. This evidence supports the development of strategies aimed at improving sleep behaviors and optimizing shoulder usage patterns as effective measures to prevent SIS.

OBJECTIVE: To evaluate the diagnostic value of musculoskeletal ultrasound measurements of subacromial bursa (SAB) thickness, supraspinatus tendon (SUP) thickness, acromiohumeral distance (AHD), and SUP-to-AHD ratio (AHD%) in patients with shoulder impingement syndrome (SIS).
METHODS: This was a prospective cross-sectional observational study. Thirty patients with SIS (60 shoulders) admitted between January 2019 and January 2020 were enrolled. The SUP thickness, SAB thickness, AHD, and AHD% (calculated as AHD% = [(SUP / AHD) × 100%]) were measured in 60 shoulders using musculoskeletal ultrasound.
RESULTS: The affected shoulder displayed thicker SUP and SAB (t = 7.838), narrower AHD (t = 2.324), and larger AHD% (t = 6.875) than the unaffected shoulder (P < .05). The SUP thickness showed a linear positive correlation with AHD (r = .503) and AHD% (r = .792) in the affected shoulder (P < .05). On receiver operating characteristic analysis, AHD*AHD% showed the best diagnostic performance in both measurements (area under the curve: 0.877).
CONCLUSIONS: This study revealed that SIS symptoms may be related to a larger AHD% with SUP thickening. As diagnostic criteria, the cut-off values of AHD% (65.6%) and AHD*AHD% (0.504) have good sensitivity and specificity and can help improve the differential diagnosis of patients with SIS.

BACKGROUND: Several surgical techniques are used to treat bursal-side partial thickness rotator cuff tears (PTRCTs). However, use of single knotless-anchor with two Ethicon 2# repair technique for PTRCTs has not been reported.
METHODS: Bursal-side PTRCTs (Ellman grade III, 75% thickness of tears) were created in the supraspinatus tendon in 16 fresh-frozen cadaveric shoulders. The specimens were randomly assigned to two equal groups: (1) Group A (Transtendon repair), a single knotless-anchor repair with two Ethicon 2#; (2) Group B, Conversion repair (Double-row, DR). Post-repair, each specimen was subjected to cyclic loading test from 5 to 100 N (50 cycles), followed by an ultimate failure test. The displacement of greater tuberosity (mm) and ultimate (N) were recorded. In the clinical study, 12 patients diagnosed with Ellman grade III Bursal-side PTRCTs (using a single knotless anchor with two Ethicon 2# repair techniques) were operated on and analyzed. Visual analog scale (VAS), American Shoulder and Elbow Surgeons Score (ASES), Constant-Murley Score (CMS), and range of motion (ROM) were assessed before surgery and at final minimum follow-up (>1year).
RESULTS: There was no significant between-group difference with respect to load-to-failure test (Group A, 359.25 ± 17.91 N; Group B, 374.38 ± 13.75 N, P > 0.05). There were no significant differences with respect to rotator cuff displacement of 10 mm (Group A, 190.50 ± 8.52 N; Group B, 197.25 ± 6.84 N, P > 0.05) and 15 mm (Group A, 282.25 ± 12.20 N; Group B, 291.13 ± 14.74 N, P > 0.05). However, there was significant between-group difference with respect to displacement of 3 and 5 mm (P < 0.05). In the clinical trial, all patients were followed up for an average of 20.4 months (12-29 months). At the last follow-up after surgery(minimum>1year), the VAS score was 0.50 ± 0.67 (0-2), the ASES score was 86.50 ± 3.96 (79-92), the CMS score was 85.08 ± 5.65 (74-93), the mean Forward flexion ROM was 154.00°± 12.48° (131°-169°), and the abduction ROM was 165.00°±13.26° (138°-173°). There was a statistically significant difference between the results of the preoperative and the last postoperative follow-up. The results of the last postoperative follow-up were statistically different from those of the preoperative follow-up (P < 0.05). Regarding complications, stiffness (2 cases) and shoulder impingement (1 case) occurred in 3 cases (25%).
CONCLUSIONS: A single knotless anchor with two Ethicon 2# may provide a biomechanically and clinically feasible option for the treatment of bursal-side Ellman grade III PTRCTs, particularly in resource-constrained settings.
UNASSIGNED: Bursal-side Ellman Grade III; Single Knotless-anchor; Double-row repair; Biomechanical study; Short-term clinical evaluation.

OBJECTIVE: Rotator cuff injury caused by subacromial impingement presents different morphologies. This study aims to investigate the correlation between various shoulder anatomical indexes on X-ray with subacromial impingement and morphology of rotator cuff tears to facilitate surgical management.
METHODS: This retrospective study was carried out between January 2020 and May 2022. Patients who were diagnosed as sub-acromial impingement associated with rotator cuff tears (without tendon retraction) and received arthroscopic surgery were enrolled in this study. The radiographic indexes of acromial slope (AS), acromial tilt (AT), lateral acromial angle (LAA), acromial Index (AI), and sub-acromial distance (SAD) were measured on preoperative true AP view and outlet view. The location of rotator cuff tear (anterior, middle, posterior, medial, and lateral) and morphology of tear (horizontal, longitudinal, L-shaped, and irregular shaped) were evaluated by arthroscopy. Groups were set up due to different tear location and tear morphologies, by comparing the various radiographic indices between each group (one-way analysis of variance and t-test), the correlation between radiographic indices and tear characteristics was investigated.
RESULTS: We analyzed 92 shoulders from 92 patients with a mean age of 57.23 ± 8.45 years. The AS in anterior tear group (29.32 ± 6.91°) was significantly larger than that in middle tear group (18.41 ± 6.13°) (p = 0.000) and posterior tear group (24.01 ± 7.69°) (p = 0.041). The AS in posterior tear group (24.01 ± 7.69°) was significantly larger than that in middle tear group (18.41 ± 6.13°) (p = 0.029). The LAA in middle tear group (67.41 ± 6.54°) was significantly smaller than that in posterior group (72.74 ± 8.78°) (p = 0.046). The AS in longitudinal tear group (26.86 ± 8.41°) was significantly larger than that in horizontal tear group (22.05 ± 9.47°) (p = 0.035) and L-shaped group (21.56 ± 6.62°) (p = 0.032). The LAA in horizontal group (70.60 ± 6.50°) was significantly larger than that in L-shaped group (66.39 ± 7.31°) (p = 0.033). The AI in L-shaped tear group (0.832 ± 0.074) was significantly larger than that in horizontal tear group (0.780 ± 0.084) (p = 0.019) and irregular tear group (0.781 ± 0.068) (p = 0.047).
CONCLUSIONS: Acromion with a larger AS and a smaller LAA tend to cause anterior or posterior rotator cuff tears rather than middle tears in sub-acromial impingement. Meanwhile acromion with a larger AS tends to cause a longitudinal tear, a larger LAA tends to cause horizontal tears and a larger AI tends to cause L-shaped tears.

OBJECTIVE: To investigate the clinical effect of Kinesio Taping combined with electroacupuncture in the treatment of Bigliani typeⅠsubacromial impingement syndrome.
METHODS: From January 2019 to June 2021, 82 cases with Bigliani typeⅠsubacromial impingement syndrome were selected and divided into treatment group and control group. Treatment group included 41 cases, 23 males and 18 females, aged from 20 to 52 years old, with an average of (39.31±5.80)years old. There were 12 cases on left shoulder and 29 cases on right shoulder. The course of disease was from 3.2 to 35.4 months. The treatment group was treated with Kinesio Taping and electroacupuncture. In control group, there were 41 cases, including 22 males and 19 females, aged from 19 to 53 years old with an average of (40.67±6.13) years old, 30 cases on right shoulder, 11 cases on left shoulder. The courses of disease was from 3.0 to 36.0 months. The control group was treated with simple shoulder electroacupuncture. Patients in both groups were treated with electroacupuncture 3 times a week for 3 weeks. After each electroacupuncture treatment in the treatment group, the Kinesio Taping was applied immediately and kept for 2 days. Before treatment, immediately after treatment, and after 1, 3, 8 weeks, the shoulder joint Constant-Murley score, pain visual analogue scale (VAS), and shoulder joint range of motion were used to evaluate the treatment effect.
RESULTS: After 1 week of treatment, there was 1 patient in treatment group refused treatment due to hypersensitivity to Kinesio Taping, 1 patient in control group was allergic to the metal needle and refused treatment. And the other 80 patients completed all treatment. Immediately after treatment, and 1, 3, and 8 weeks after treatment, VAS of treatment group were (2.06±1.03), (2.74±1.66), (3.28±1.04), and (3.90±0.12) points, respectively. The Constant-Murley scores of shoulder joint were(86.41±3.52), (82.44±3.14), (80.46±2.54), (76.97±2.01) points. VAS of control group were(3.35±0.41), (3.08±0.92), (3.77±0.67), (3.96±1.04) points, and the Constant-Murley scores of the shoulder joint were(75.82±2.73), (74.72±1.53), (73.66±1.53), (70.68±1.95) points respectively. Immediately after treatment, VAS, Constant-Murley score, and shoulder range of motion between two groups were better than those of before treatment (P<0.05), and the difference was statistically significant between two groups after treatment (P<0.05). One week after treatment, VAS, Constant-Murley score, and shoulder joint range of motion between two groups were better than those of before treatment (P<0.05), but there was no significant difference in VAS between two groups (P>0.05). There were significant differences in the Constant-Murley score and shoulder range of motion between two groups (P<0.05). At 3 and 8 weeks after treatment, VAS, Constant-Murley score, and the range of motion of shoulder joints between two groups were better than those of before treatment (P<0.05), but there was no significant difference between two groups(P>0.05).
CONCLUSIONS: The treatment for bigliani typeⅠsubacromial impingement syndrome with Kinesio Taping combined with electroacupuncture can reduce pain, effectively improve the function of shoulder joint. In addition, with Kinesio Taping protection when motion, the patients sports ability can be improved obviously, with good immediate effect, and no trauma. If the patients are willing to accept it, it would be an immediate and effective treatment.

BACKGROUND: Distal clavicular fracture is a shoulder joint injury that is common in clinical settings and is generally surgically treated using the clavicular hook plate technique with a confirmed curative effect. However, symptoms, such as shoulder abduction limitation, shoulder discomfort, and postoperative joint pain, may occur in some patients. To overcome these problems, after a previous study we developed an acromial height-measuring device and a new type of clavicular hook plate. This study aimed to investigate whether an acromial height-measuring device combined with an improved new-type clavicular hook plate can better reduce the incidence of complications and improve postoperative function. To provide patients with better treatment effects, an acromion gauge and clavicular hook plate are used.
METHODS: A retrospective analysis was performed on 81 patients with distal clavicular fractures admitted to our hospital. They were divided into experimental and control groups according to different plates, and the Constant-Murley score, visual analogue scale score, incidence of acromion osteolysis, and incidence of subacromial impingement syndrome were compared.
RESULTS: Compared with the standard clavicular hook plate, the acromial height-measuring device combined with the new-type clavicular hook plate in the treatment of distal clavicle fractures has a lower incidence of subacromial impingement syndrome with better postoperative functional recovery and quality of life.
CONCLUSIONS: We considered the acromial height-measuring device combined with the new clavicular hook plate to be a safe and promising alternative to distal clavicular fractures.

OBJECTIVE: To develop a new classification of acromion based on the subacromial impingement theory and the Rockwood tilt view. And explore the application value of the new classification in the diagnosis and treatment of rotator cuff tear.
METHODS: The clinical data of 101 patients underwent shoulder arthroscopic surgery for impingement syndrome or rotator cuff tear from January to December 2017 were retrospectively analyzed. There were 34 males and 67 females, aged from 34 to 76 years with an average of (56.31±9.63) years old, course of disease from 2 to 12 months with average of 6 months. Preoperative radiographs of the routine anteroposterior view, Rockwood tilt view and the supraspinatus outlet view were obtained. Based on the subacromial impingement theory and Rockwood radiographs, the morphology of the acromion can be divided into three types:typeⅠ(flat type), typeⅡ(bump type), and type Ⅲ (impingement type). Two observers classified 101 shoulder Rockwood radiographs according to the new classification method and the supraspinatus Outlet radiographs according to the traditional acromial morphological classification method. Supraspinatus tendon injuries were classified into no tear, partial-thickness tear, and full-thickness tear according to the arthroscopic findings. Concordance test (Kappa value) between the inter-observer and intra-observer was carried out for the new classification method and the traditional classification method respectively. The rank sum test was used to compare the mean acromiohumeral distance(AHD) of the three acromion forms in the new acromion classification method. Spearman rank correlation test and Gamma method were used to analyze the correlation between the new acromion classification method and the degree of supraspinatus tendon tear.
RESULTS: The inter-observer consistency analysis of the new classification system was significantly better than that of the traditional classification (0.827 vs 0.278), the intra-observer consistency analysis of the new classification system were also significantly better than that of the traditional classification (0.921 vs 0.448, 0.890 vs 0.539). There was no statistical significance in the AHD among three types of the new classification(H=2.186, P>0.05). In all 101 patients, the highest proportion of impingement type acromion was 45.5% (46 cases), followed by bump type acromion was 36.6% (37 cases), and flat type acromion was 17.8% (18 cases). The incidence of supraspinatus tendon tear in the patients with impingement type acromion was significantly higher than that of the other two types of acromion, there was a spearman rank correlation between the new acromion type and the degree of the supraspinatus tendon tear(rs=0.719, P<0.001).
CONCLUSIONS: Rockwood radiographs of the shoulder can well display the anterolateral osteophytes of the acromion. The new acromion classification method based on Rockwood radiographs has high reliability and good reproducibility, in which impingement type of acromion is closely related to supraspinatus tendon tear. Compared with the traditional classification and AHD, the new classification method has more diagnostic value than for rotator cuff injury.