The frequency of os acromiale in 751 shoulder MRI of Saudi population.

Background: Os acromiale (OA) is an uncommon pathology with a variable prevalence rate among different populations. Objectives: The aim of this study was to report the frequency of OA utilizing shoulder MRI of patients with shoulder pathology. Methods: It was a retrospective study. After obtaining our IRB approval, we gathered all shoulder and upper arm MRIs from the radiology department and evaluated them. Results: The prevalence of OA was found to be 3.32%. The mean age of the affected patients was 50.87 years (25-81). Conclusion: The rate of OA in patients presenting with shoulder pain is 3.32% in Saudi Arabia, which correlates with what has been previously reported in the literature.

Distribution and analysis of subacromial spurs and the relationship with acromial classification and angle in healthy individuals.

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.

Robert H. Cofield, MD, Award for Best Oral Presentation 2023: Up to 8 mm of glenoid-sided lateralization does not increase the risk of acromial or scapular spine stress fracture following reverse shoulder arthroplasty with a 135° inlay humeral component.

BACKGROUND: Glenoid-sided lateralization in reverse shoulder arthroplasty (RSA) decreases bony impingement and improves rotational range of motion, but has been theorized to increase the risk of acromial or scapular spine fractures (ASFs). The purpose of this study was to assess if glenoid-sided lateralization even up to 8 mm increases the risk for stress fracture following RSA with a 135° inlay humeral component. METHODS: A retrospective review was performed from a multicenter prospectively collected database on patients who underwent primary RSA from 2015 to 2021. All RSAs were performed with a 135° inlay humeral component. Varying amounts of glenoid lateralization were used from 0 to 8 mm. Preoperative radiographs were reviewed for the presence of acromial thinning, acromiohumeral distance (AHD), and inclination. Postoperative implant position (distalization, lateralization, and inclination) as well as the presence of ASF was evaluated on minimum 1-year postoperative radiographs. Regression analyses were performed on component and clinical variables to assess for factors predictive of ASF. RESULTS: Acromial or scapular spine fractures were identified in 26 of 470 shoulders (5.5%). Glenoid-sided lateralization was not associated with ASF risk (P = .890). Furthermore, the incidence of fracture did not vary based on glenoid-sided lateralization (0-2 mm, 7.4%; 4 mm, 5.6%; 6 mm, 4.4%; 8 mm, 6.0%; P > .05 for all comparisons). RSA on the dominant extremity was predictive of fracture (odds ratio [OR] 2.21, 95% confidence interval [CI] 1.20-5.75; P = .037), but there was no relationship between patient age, sex, preoperative acromial thinning, or diagnosis and risk of fracture. Although there was no difference in mean postoperative AHD between groups (P = .443), the pre- to postoperative delta AHD was higher in the stress fracture group (2.0 ± 0.7 cm vs. 1.7 ± 0.7 cm; P = .015). For every centimeter increase in delta AHD, there was a 121% increased risk for fracture (OR 2.21, 95% CI 1.33-3.68; P = .012). Additionally, for every 1-mm increase in inferior glenosphere overhang, there was a 19% increase in fracture risk (P = .025). CONCLUSION: Up to 8 mm of glenoid-sided metallic lateralization does not appear to increase the risk of ASF when combined with a 135° inlay humeral implant. Humeral distalization increases the risk of ASF, particularly when there is a larger change between pre- and postoperative AHD or higher inferior glenosphere overhang. In cases of pronounced preoperative superior humeral migration, it may be a consideration to avoid excessive postoperative distalization, but minimizing bony impingement via glenoid-sided lateralization appears to be safe.

In Vivo Analysis of Acromioclavicular Kinematics and Distance During Multiplanar Humeral Elevation.

BACKGROUND: Knowledge of acromioclavicular (AC) joint kinematics and distance may provide insight into the biomechanical function and development of new treatment methods. However, accurate data on in vivo AC kinematics and distance between the clavicle and acromion remain unknown. PURPOSE/HYPOTHESIS: The purpose of this study was to investigate 3-dimensional AC kinematics and distance during arm elevation in abduction, scaption, and forward flexion in a healthy population. It was hypothesized that AC kinematics and distance would vary with the elevation angle and plane of the arm. STUDY DESIGN: Controlled laboratory study. METHODS: A total of 19 shoulders of healthy participants were enrolled. AC kinematics and distance were investigated with a combined dual fluoroscopic imaging system and computed tomography. Rotation and translation of the AC joint were calculated. The AC distance was measured as the minimum distance between the medial border of the acromion and the articular surface of the distal clavicle (ASDC). The minimum distance point (MDP) ratio was defined as the length between the MDP and the posterior edge of the ASDC divided by the anterior-posterior length of the ASDC. AC kinematics and distance between different elevation planes and angles were compared. RESULTS: Progressive internal rotation, upward rotation, and posterior tilt of the AC joint were observed in all elevation planes. The scapula rotated more upward relative to the clavicle in abduction than in scaption (P = .002) and flexion (P = .005). The arm elevation angle significantly affected translation of the AC joint. The acromion translated more laterally and more posteriorly in scaption than in abduction (P < .001). The AC distance decreased from the initial position to 75° in all planes and was significantly greater in flexion (P < .001). The MDP ratio significantly increased with the elevation angle (P < .001). CONCLUSION: Progressive rotation and significant translation of the AC joint were observed in different elevation planes. The AC distance decreased with the elevation angle from the initial position to 75°. The minimum distance between the ASDC and the medial border of the acromion moved anteriorly as the shoulder elevation angle increased. CLINICAL RELEVANCE: These results could serve as benchmark data for future studies aiming to improve the surgical treatment of AC joint abnormalities to restore optimal function.

Acromion fractures after reverse shoulder arthroplasty occur in predictable clusters.

BACKGROUND: Acromion and scapular spine fractures (ASFs) following reverse total shoulder arthroplasty (RSA) have been reported at a rate of 3.9%. The location of the fracture has been shown to be an important factor in determining the outcomes of nonoperative treatment, with medial fractures having worse outcomes than lateral fractures. As the debate between operative and nonoperative treatment continues, a more precise understanding of the location of the fracture is necessary for effective management. The purpose of this study was to use 3-dimensional computed tomography (CT) reconstruction to characterize the exact location of ASFs after RSA. METHODS: A retrospective review of 2 separate institutional shoulder and elbow repositories was performed. Patients with post-RSA ASFs documented by post-fracture CT scans were included. The query identified 48 patients who sustained postoperative ASFs after RSA between July 2008 and September 2021. CT scans of patients with ASFs were segmented using Mimics software. Eight patients were excluded because of poor image quality. Each bone model was manipulated using 3-Matic Medical software to align the individual scapula with an idealized bone model to create a view of scapular fracture locations on a normalized bone model. This model was used to classify the fractures using the modified Levy classification. RESULTS: The study cohort consisted of 40 patients with a diagnosis of postoperative ASF after RSA. The median age at the time of surgery was 76 years (interquartile range, 73-79 years). The cohort comprised 32 women (80%) and 8 men (20%), with a median body mass index of 27.8. Only 10 patients (25%) had a previous diagnosis of osteoporosis and 6 (13%) had a diagnosis of inflammatory arthritis; 53% of patients underwent RSA owing to rotator cuff tear arthropathy. The distribution of fracture locations was similar within the cohort. However, lateral fractures were slightly more prevalent. The most common fracture location was the type I zone, with 12 fracture lines (29%). There were 11 fracture lines (26%) in the type IIa zone, 10 (23%) in the type IIb zone, 0 in the type IIc zone, and 9 (21%) in the type III zone. CONCLUSION: ASFs after RSA occur in 4 predictable clusters. No fractures appeared to distinctly cluster in the type IIc zone, which may not represent a true fracture zone. Understanding the distribution of these fractures will help to enable the future design of implants and devices to stabilize the fractures that require fixation.

Ipsilateral fractures of the acromion and coracoid processes of the scapula.

A fracture of the acromion and coracoid processes of scapula is rarely seen in the outpatient clinic, due to the acromion's anatomical position and shape, as well as the strong ligaments and muscles that are attached to it. These fractures are caused by either direct or indirect high-energy trauma injuries to the shoulder joint, leading to severe pain and a grossly restricted range of motion. Several acromial classifications were reported, but this type of longitudinal plane fracture of the acromion process in our case is yet to be described in the current literature. We present a rare combination of the coracoid process and unstable acromion bony projection fractures that have not previously been noted for this type of fracture. The closest to this is Kuhn's type III classification. A 51-year-old male presented to our emergency department complaining of the right shoulder pain and difficulty raising his arm following a 2-wheeler accident. The patient was managed by open reduction and internal fixation with 3 cannulated cancellous screws fixation and progressed well with no postoperative complications. He was asymptomatic postoperatively and regained full range of motion after 4 months.

Variability in the distance between the suprascapular notch with the spine of the scapulae and the acromion.

INTRODUCTION: The suprascapular notch lies in the superior border of the scapula and is a passageway for the suprascapular nerve that is sensory to the shoulder joint. Suprascapular nerve block involves injection of local anaesthetic into the suprascapular notch, either ultrasound guided or blind, using the spine of scapula and/or the medial border of the acromion as surface landmarks. AIM: To investigate the anatomic variations that exist between the distance of the notch from the spine of scapula and acromion. METHOD: Ninety-two dry scapulae were measured with a digital calliper for their length of the spine, distance between the midpoint of the spine and base of the suprascapular notch and distance between the medial border of the acromion and the base of the suprascapular notch. These measurements were compared for variations in the scapular bony landmarks, the spine and the acromion to determine the site for the injection. RESULTS: Measurement reliability was assessed by intraclass correlation, Cronbach's alpha being 0.99, 0.97 and 0.91 for length of spine, distance from spine and distance from acromion respectively. The distance from the acromion had less variation in measurement (3.73 ± 0.42 cm) but a flatter distribution when compared to distance from the spine of the scapula (3.32 ± 0.39 cm). CONCLUSION: Length of the spine of the scapula appeared not to influence either distance from the acromion or distance from the spine of scapula. There is potential for greater variability in placement of nerve blocks that use acromion as the bony reference. Key Points • Dry scapular measurement using electronic Vernier callipers is accurate (0.91-0.97). • There is potential for greater variability in placement of blind nerve blocks that use acromion as the bony reference to locate the suprascapular notch.

Giant Cell Tumor of the Acromion: Case Report and Literature Review.

BACKGROUND/AIM: Giant cell tumor of bone (GCTB) is a locally aggressive neoplasm that typically occurs in the ends (epiphyses) of long bones of young adults. Flat bones are uncommon sites of involvement. Herein, we describe an unusual case of pathologically proven GCT of the acromion. CASE REPORT: The patient was a 39-year-old woman with no history of trauma who presented with a 3-month history of right posterior shoulder pain. Physical examination revealed mild swelling and tenderness in the posterior aspect of the right shoulder. Plain radiograph showed a purely lytic lesion, suggestive of a bone tumor. Computed tomography demonstrated an intraosseous lytic lesion with associated cortical thinning and lack of periosteal reaction. On magnetic resonance imaging, the lesion exhibited slightly higher signal intensity compared to skeletal muscle on T1-weighted sequences and heterogeneous high signal intensity on T2-weighted sequences. Strong enhancement was observed following gadolinium administration. The lesion was treated by extensive curettage with adjuvant therapy comprising ethanol and the remaining cavity was filled with polymethylmethacrylate bone cement. Histologically, the lesion was composed of round or spindle-shaped mononuclear cells admixed with numerous osteoclast-like giant cells. Immunohistochemically, the mononuclear neoplastic cells were diffusely positive for H3.3 G34W. The patient was asymptomatic and there was no evidence of local recurrence or distant metastasis 5 months after surgery. CONCLUSION: Although rare, acromial GCTB should be considered in the differential diagnosis of posterior shoulder pain, especially in young and early middle-aged adults.

Changes in the Lateral Acromion Angle in Rotator Cuff Tear Patients with Acromioplasty.

BACKGROUND: Arthroscopic surgery has been established as an efficacious intervention for the treatment of rotator cuff tears. The primary aim of this study was to analyze the modifications in the lateral acromial angle (LAA) subsequent to rotator cuff repair surgery using single-row rivet fixation and double-row rivet fixation techniques. Furthermore, we sought to investigate the influence of LAA on the prognosis of rotator cuff repair surgery. METHOD: This observational study retrospectively enrolled 105 patients diagnosed with degenerative rotator cuff tears who underwent arthroscopic rotator cuff repair between 2016 and 2019. Following the exclusion of two patients with subscapularis or superior labrum anterior and posterior (SLAP) tears, as well as three patients who were lost to follow-up, a cohort of 100 patients was included for clinical and imaging evaluation. Among these individuals, 50 were assigned to the double-row repair group, whereas the remaining 50 comprised the single-row repair group. Bilateral shoulder magnetic resonance imaging (MRI) scans were conducted no less than 24 months post-surgery. Experienced arthroscopic surgeons, blinded to the LAA measurements, assessed the rotator interval (RI) using a control MRI. Functional assessment was performed using the University of California, Los Angeles (UCLA) quick disability of the shoulder and arm, shoulder and hand (qDASH) score. The Wilcoxon signed-rank test for dependent samples was employed to compare data between the pre- and post-intervention groups. Pearson correlation coefficients were calculated to evaluate the relationship between different parameters. RESULTS: The study population consisted of 73 female patients and 27 male patients, with a mean age of 58.32 ± 5.29 years and a mean follow-up duration of 25.88 ± 8.11 months. Preoperatively, the mean LAA was 75.81° ± 11.28°, RI was 4.78 ± 0.62, UCLA score was 17.54 ± 2.44, and qDASH score was 2.45 ± 0.25. The average tear size was 8.95 ± 2.11 mm. A statistically significant difference in LAA was observed between the preoperative and postoperative measurements, with the double-row repair group exhibiting a greater LAA than the single-row repair group. Finally, a significant correlation was identified between LAA, RI, and qDASH scores after a 24-month follow-up period. CONCLUSION: According to our findings, the utilization of double-row rivet fixation has a greater LAA angle than single-row rivet fixation. Moreover, this preservation of LAA is significantly associated with the functional recovery of the shoulder joint.

The role of bone morphology of the greater tuberosity and lateral acromion on subacromial space during scaption: a three-dimensional dynamic simulation analysis.

BACKGROUND: The bone morphology of the greater tuberosity and lateral acromion plays a central role in subacromial impingement syndrome. The critical shoulder angle (CSA) and greater tuberosity angle (GTA) are two-dimensional measurement parameters that have been validated to evaluate it radiologically. These markers are, however, static and don't consider the dynamic effect of glenohumeral motion. OBJECTIVES: This study aimed to better understand the biomechanics in subacromial impingement with a dynamic simulation based on a validated 3D biomechanical model coupling joint kinematics and 3D reconstructed computed tomography. STUDY DESIGN & METHODS: Sixty-one patients were included in this study: a case group of 44 patients with degenerative rotator cuff tears involving only the supraspinatus, and a control group of 17 without a rotator cuff tear. Patients with previous surgeries, traumatic cuff tears, and cuff tear arthropathy were excluded. CSA, GTA, and impingement-free range of motion (IF-ROM) of the glenohumeral joint in scaption were calculated. Correlation tests were used to determine the relationship between ROM and CSA, GTA, and combined CSA and GTA values. RESULTS: CSA and GTA were significantly higher in the rotator cuff tear group (p = 0.001 and < 0.001), while IF-ROM was significantly higher in the control group (p = 0.001). There was no overall correlation between CSA and GTA (R = 0.02, p = 0.8). Individual correlation between both angles with IF-ROM was negatively weak for CSA (R = -0.4, p < 0.001) and negatively moderate for GTA and IF-ROM (R = -0.5, p < 0.001). However, combining both angles resulted in a negatively high correlation with IF-ROM (R = -0.7, p < 0.001). CONCLUSION: Subacromial space narrowing during scaption is highly correlated to the cumulative values of GTA and CSA. These findings suggest that the combined bony morphology of the lateral acromion and greater tuberosity plays an important role in subacromial impingement. LEVEL OF EVIDENCE: III.

Deep learning for automated measurement of CSA related acromion morphological parameters on anteroposterior radiographs.

BACKGROUND: The Critical Shoulder Angle Related Acromion Morphological Parameter (CSA- RAMP) is a valuable tool in the analyzing the etiology of the rotator cuff tears (RCTs). However, its clinical application has been limited by the time-consuming and prone to inter- and intra-user variability of the measurement process. OBJECTIVES: To develop and validate a deep learning algorithm for fully automated assessment of shoulder anteroposterior radiographs associated with RCTs and calculation of CSA-RAMP. METHODS: Retrospective analysis was conducted on radiographs obtained from computed tomography (CT) scans and X-rays performed between 2018 and 2020 at our institution. The development of the system involved the utilization of digitally reconstructed radiographs (DRRs) generated from each CT scan. The system's performance was evaluated by comparing it with manual and semiautomated measurements on two separate test datasets: dataset I (DRRs) and dataset II (X-rays). Standard metrics, including mean average precision (AP), were utilized to assess the segmentation performance. Additionally, the consistency among fully automated, semiautomated, and manual measurements was comprehensively evaluated using the Pearson correlation coefficient and Bland-Altman analysis. RESULTS: A total of 1080 DRRs generated from 120 consecutive CT scans and 159 X-ray films were included in the study. The algorithm demonstrated excellent segmentation performance, with a mean AP of 57.67 and an AP50 of 94.31. Strong inter-group correlations were observed for all CSA-RAMP measurements in both test datasets I (automated versus manual, automated versus semiautomated, and semiautomated versus manual; r = [0.990---0.997], P < 0.001) and dataset II (r = [0.984---0.995], P < 0.001). Bland-Altman analysis revealed low bias for all CSA-RAMP measurements in both test datasets I and II, except for CD (with a maximum bias of 2.49%). CONCLUSIONS: We have successfully developed a fully automated algorithm capable of rapidly and accurately measuring CSA-RAMP on shoulder anteroposterior radiographs. A consistent automated CSA- RAMP measurement system may accelerate powerful and precise studies of disease biology in future large cohorts of RCTs patients.

Correlation of Acromial Morphology With Risk and Direction of Shoulder Instability: An MRI Study.

BACKGROUND: The influence of bony morphology on the development of posterior shoulder instability is not well known. PURPOSE: To determine if acromial morphology, as measured on magnetic resonance imaging (MRI), is associated with posterior or anterior shoulder instability. DESIGN: Cross-sectional study; Level of evidence, 3. METHODS: MRI measurements of posterior acromial coverage (PAC), posterior acromial height (PAH), posterior acromial tilt (PAT), and anterior acromial coverage (AAC) were completed for 3 separate matched groups who underwent surgical intervention: posterior instability, anterior instability, and a comparison group of patients who underwent arthroscopic surgery for snapping scapula. Inclusion criteria were patients with recurrent instability <40 years of age without multidirectional instability, glenoid bone loss >13.5%, or glenoid retroversion >10%. RESULTS: Overall, 37 patients were included in each group. PAC was significantly less in the posterior instability group than in the anterior instability and comparison groups (68.3° vs 88.7° vs 81.7°; P < .001). PAH was significantly greater in the posterior group than in the anterior instability group (11.0 mm vs -0.1 mm; P < .001) and comparison group (0.7 mm; P < .001). There was no difference between the posterior and anterior groups in terms of PAT or AAC (P = .45 and P = .05, respectively). PAT was significantly smaller in the posterior instability group than the comparison group (55.2° vs 62.2°; P = .026). The anterior and comparison groups were not significantly different in PAH or PAT (P = .874 and P = .067, respectively) but were significantly different in AAC (P = .026). CONCLUSION: A higher and flatter posterior acromion, as measured on preoperative MRI, appears to be associated with patients who require arthroscopic capsulolabral repair due to posterior shoulder instability. This information may help clinicians to both diagnose and predict the need for operative intervention for patients with posterior labral tears.

Effect of Anterior Acromial Coverage on Functional and Radiological Outcomes After Arthroscopic Repair of Anteroposterior Massive Rotator Cuff Tears.

BACKGROUND: Rotator cuff tear size, fatty infiltration, and scapular morphology are correlated with tendon healing and functional outcomes after arthroscopic repair; however, the association between anteroposterior acromial coverage and the clinical outcomes of anteroposterior massive rotator cuff tears (AP-MRCTs; involving all 3 tendons) remains unclear. PURPOSE: To identify the association between AP acromial coverage and functional and radiological outcomes after arthroscopic repair of AP-MRCTs. STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: A total of 98 patients who underwent arthroscopic repair of AP-MRCTs between January 2015 and December 2020 were included in the study and classified according to whether anterior acromial coverage (AAC) was anterior (46 patients; positive AAC group) or posterior (52 patients; negative AAC group) to the scapular line on true lateral shoulder radiographs. Demographic characteristics, surgical details, and functional outcomes were prospectively collected. Acromial morphological features, global tear extension (GTE), the global fatty infiltration index (GFII), tendon integrity after repair, proximal humeral migration, and glenohumeral abduction were measured and calculated on radiographs or magnetic resonance imaging scans preoperatively and at 2 years postoperatively. Multivariate logistic regression was performed to identify the independent risk factors of a rotator cuff retear. RESULTS: The positive AAC group showed larger AAC, posterior acromial tilt, and anterior acromial slope as well as smaller posterior acromial coverage compared with the negative AAC group. Postoperatively, the American Shoulder and Elbow Surgeons score (82.5 ± 8.3 vs 77.2 ± 11.5, respectively; P = .013), active abduction (157.8°± 27.1° vs 142.7°± 39.6°, respectively; P = .048), and glenohumeral abduction (45.6°± 10.4° vs 39.7°± 14.9°, respectively; P = .041) in the positive AAC group were significantly higher than those in the negative AAC group, while the retear rate (23.9% vs 44.2%, respectively; P = .035) and proximal humeral migration (1.7 ± 1.0 vs 2.3 ± 1.2 mm, respectively; P = .006) were significantly lower in the positive AAC group than in the negative AAC group. Smaller AAC (odds ratio [OR], 0.93 [95% CI, 0.87-1.00]; P = .040), larger GTE (OR, 1.03 [95% CI, 1.01-1.06]; P = .017), and a higher GFII (OR, 3.49 [95% CI, 1.09-11.19]; P = .036) were associated with an increased risk of a rotator cuff retear. CONCLUSION: Increased AAC was associated with a lower retear rate and better functional outcomes after arthroscopic repair of AP-MRCTs. A preliminary risk evaluation integrating GTE, the GFII, and AAC is recommended to consider the necessity of additional procedures for patients in need of arthroscopic rotator cuff repair.

Use of Distal Clavicle Autograft in the Treatment of Os Acromiale Open Reduction Internal Fixation: A Surgical Case Report.

CASE: We present a case of a 21-year-old male patient with a symptomatic os acromiale treated with open reduction internal fixation with distal clavicle autograft. The patient presented with right shoulder pain after a motor vehicle accident with tenderness over the acromion. Radiographs demonstrated an os meso-acromion with corresponding edema on Magnetic Resonance Imaging (MRI). The patient recovered uneventfully with radiographic fusion at 8 months of the os acromiale site. CONCLUSION: This case used the excised distal clavicle as autograft. This technique has the added advantage of harvesting autograft from the same surgical approach and potential mechanical advantage of offloading the os acromiale site to promote healing.

Nonunion of the so-called acromion: a systematic review with consideration of the terminology.

INTRODUCTION: There is no widely accepted standard for the classification and treatment of traumatic acromion/scapular spine fracture nonunion due to the scarcity of this condition and the confusion of terminology. MATERIALS AND METHODS: PubMed and Scopus were searched using "scapular fracture" and "acromion fracture" or "scapular spine fracture" as search terms. The inclusion criteria were English full-text articles concerning acromion/scapular spine fracture nonunion that described patient characteristics and presented appropriate images. The exclusion criteria were cases without appropriate images. Citation tracking was conducted to find additional articles and notable full-text articles written in other languages. Fractures were classified using our newly proposed classification system. RESULTS: Twenty-nine patients (19 men, 10 women) with 29 nonunions were identified. There were four type I, 15 type II, and 10 type III fracture nonunions. Only 11 fractures were isolated. The mean period from initial injury to final diagnosis was 35.2 ± 73.2 months (range 3-360 months) (n = 25). The most frequent cause of delayed diagnosis was conservative treatment for fracture in 11 patients, followed by oversight by the physician in 8. The most common reason for seeking medical advice was shoulder pain. Six patients received conservative therapy, and 23 received operative treatment. Fixation materials included various plates in 15 patients, and tension band wiring in 5. Bone grafting was performed in 16 patients (73%, 16/22). Of the 19 surgically treated patients with adequate follow-up, the outcome was rated excellent in 79%. CONCLUSIONS: Isolated acromion/scapular spine fracture nonunion is rare. Fracture type II and III, arising in the anatomical scapular spine, accounted for 86% of the fractures. Computed tomography is required to prevent fracture oversight. Surgical therapy produces good stable results. However, it is important to select the appropriate surgical fixation method and material after considering the anatomical characteristics of the fracture and stress on the fractured portion. LEVEL OF EVIDENCE: V.

[Treatment of symptomatic pseudarthrosis following acromion fracture with a patient-specific implant customized on a 3D-printed scapula]. / Versorgung symptomatischer Pseudarthrosen nach Akromionfraktur mit patientenspezifisch am 3-D-Modell angepasstem Implantat.

OBJECTIVE: Patient-specific osteosynthesis for pseudarthrosis of the acromion. INDICATIONS: Symptomatic pseudarthrosis of the acromion at the level of a meta/mesacromion. CONTRAINDICATIONS: Infection; patient noncompliance regarding postoperative treatment protocol. SURGICAL TECHNIQUE: Preoperatively, a patient-specific three-dimensional model of the scapula is printed. A locking compression plate (LCP) is individually adapted to this model. Via a dorsal surgical approach over the scapular spine, the pseudarthrosis is refreshed and autologous cancellous bone from the iliac crest is embedded in the fracture zone. This is followed by fixed-angle osteosynthesis with the individualized plate. In addition, tension banding with tapes is performed to reduce the tensile and shear forces on the fracture caused by the muscle. POSTOPERATIVE MANAGEMENT: Consistent wearing of a shoulder-arm brace for 6 weeks postoperatively, active-assisted increase in range of motion for an additional 3 weeks, then gradual increase in weight-bearing and initiation of daily activities without additional weights until 12 weeks postoperatively. RESULTS: Treatment with the presented technique resulted in radiographic consolidation of the fracture and significant improvement in range of motion and pain at the 1­year follow-up.

Capsular remnant in the rotator cuff footprint is a novel arthroscopic finding may indicate the etiology of the tear.

PURPOSE: The aim of the study was that the capsule remnant is a common indicator of sub-acromial impingement syndrome and bursal side onset rotator cuff tears. METHODS: Sixty-three patients with capsule remnants in the rotator cuff footprint (Study group) were detected, while the 53 patients did not have any remnant on the tendon footprint (Control group) between 2015 and 2020 were included. Demographic data of patients, such as age, gender, and operated side information were obtained from the archive files. Acromion type, presence of osteophytes in the acromioclavicular joint, Acromiohumeral Distance (AHD), Acromial Index (AI), Critical Shoulder Angle (CSA), and Coracoacromial Ligament (CAL) degeneration values were evaluated from preoperative MRI, radiographic images, and arthroscopic video recordings. RESULTS: Severe stages of CAL degeneration were observed in 82.5% of the patients who had capsule remnant (p: 0.001). While type 2 acromion was found in 61.9%, and also acromioclavicular joint osteophyte was found in 58.7% of the patients in the study group. The mean AHD was 8.22 ± 1.56 mm in the study group and 9.2 ± 1.3 mm in the control group. The mean CSA was 43.3 ± 4.9 in the study group and 40.8 ± 4.2 in the control group. The AI was measured as 0.8 ± 0.1 in the study group and 0.8 ± 0.01 in the control group. As a result of these measurements, a statistical difference was found between the two groups in terms of type 2 acromion ratio (p < 0.001), presence of osteophytes in the acromioclavicular joint (p < 0.001), mean acromio-humeral distance (p < 0.001), critical shoulder angle (p = 0.004), and acromial index values (p < 0.001). CONCLUSION: The findings of sub-acromial impingement syndrome were found to be more prominent in patients with full-thickness degenerative tear and findings of capsular remnant in the footprint. If the presence of the current finding is detected during glenohumeral arthroscopy, sub-acromial impingement syndrome should be examined in more detail to reveal the underlying cause and prevent a recurrence.

Acromion morphology is associated with glenoid bone loss in posterior glenohumeral instability.

BACKGROUND: The acromion morphology in a shoulder with posterior instability differs from that of a shoulder without glenohumeral instability. Specifically, the acromion with a flatter sagittal tilt, greater posterior acromial height, and less posterior coverage is associated with posterior instability. However, the association between acromion morphology and glenoid bone loss (GBL) in the setting of posterior glenohumeral instability has not previously been investigated. The purpose of this study was to determine whether acromial morphology influences the extent or pattern of posterior GBL in a cohort of patients with posterior glenohumeral instability. METHODS: This multicenter retrospective study identified 89 shoulders with unidirectional posterior glenohumeral instability. Total area GBL was measured using the best-fit circle method on magnetic resonance imaging (MRI). Shoulders were divided into 3 groups: (1) no GBL (n = 30), (2) GBL 0%-13.5% (n = 45), or (3) GBL ≥13.5% (n = 14). Acromion measurements were performed on MRI and included acromial tilt, posterior acromial height, anterior acromial coverage, and posterior acromial coverage. RESULTS: Patients without GBL had a steeper acromial tilt (58.5° ± 1.4°) compared with those with 0%-13.5% GBL (64.3° ± 1.5°) or GBL ≥13.5% (67.7° ± 1.8°) (P = .004). Patients without GBL also had greater posterior coverage (65.4° ± 1.7°) compared with those with GBL (60.3° ± 1.4°) (P = .015). Posterior acromion height was not significantly different among groups. CONCLUSION: The results demonstrate that an acromion with a flatter sagittal tilt and less posterior coverage is associated with GBL in the setting of posterior glenohumeral instability. This is important to consider as posterior GBL has been identified as a risk factor for failure of posterior soft tissue-stabilizing procedures.

High Acromial Slope and Low Acromiohumeral Distance Increase the Risk of Retear of the Supraspinatus Tendon After Repair.

BACKGROUND: Retearing of the supraspinatus (SSP) tendon after repair is relatively common, but its cause is rarely clear. Although the role of acromion morphology and glenoid orientation in the pathogenesis of primary SSP tendon tears have frequently been analyzed, their association with the risk of rerupture of a repaired SSP tendon is poorly understood. QUESTIONS/PURPOSES: (1) Is acromial morphology associated with the risk of retear after SSP tendon repair? (2) Is there an association between inclination and version of the glenoid and the odds for retear of the SSP tendon after repair? (3) Are there differences in outcome scores between patients who had intact cuff repairs and those who had retears? METHODS: Between August 2012 and December 2015, we treated 92 patients for SSP tendon tears; all of these patients were considered for inclusion in the present study. We considered patients with complete tear of the SSP that was reconstructed with a double-row repair and a minimum follow-up of 2 years as potentially eligible. Based on these criteria, 28% (26 of 92) were excluded because they had a partial rupture and did not receive a double-row reconstruction. A further 9% (eight of 92) were excluded because of missing planes or slices (such as sagittal, axial, or frontal) on MRI, and another 3% (three of 92) were lost before the minimum study follow-up interval or had incomplete datasets, leaving 60% (55 of 92) for inclusion in the present analysis. All included patients had a minimum follow-up of 2 years; follow-up with MRI occurred at a mean duration of 2.3 ± 0.4 years postoperatively. All patients were asked to complete the Western Ontario Rotator Cuff Index and Oxford Shoulder Scores, and they underwent MRI of the operated-on shoulder. Preoperative true AP radiographs and MR images of the affected shoulders were retrospectively assessed by measuring the acromiohumeral interval, critical shoulder angle, acromial slope, acromial tilt, acromial index, lateral acromial angle, and glenoid version and inclination. The patients also underwent acromioplasty, in which the underface of the acromion was flattened. To rule out any change in the above parameters because of acromioplasty, these parameters were compared using preoperative and postoperative MR images and showed no difference. In addition, the tendon integrity and quality on postoperative MRI were analyzed independently of one another by the same two observers using the Sugaya and Castricini classifications, accounting for atrophy and fatty degeneration of the SSP muscle. To assess interobserver reliability, the two observers took measurements independently from each other. They were orthopaedic residents who completed a training session before taking the measurements. All measurements had excellent intrarater (Cronbach alpha 0.996 [95% confidence interval (CI) 0.99 to 1.00; p > 0.01) and interrater (interrater correlation coefficient 0.975 [95% CI 0.97 to 0.98]; p > 0.01) reliabilities. To answer the study's first question, SSP integrity on postoperative MRI was compared with acromial morphologic parameters measured on preoperative AP radiographs and MR images. To answer the second question, the postoperative integrity and quality of the SSP tendon were correlated with glenoid inclination and glenoid version. To answer our third question, we compared outcome scores between patients with intact SSP tendons and those with reruptured SSP tendons. To investigate any correlation among the acromial morphology, glenoid orientation, and postoperative outcomes, a binomial logarithmic regression analysis was performed. Receiver operating characteristic curves were used to determine cutoff points for the radiologic parameters that showed a correlation in the binomial regression analysis. RESULTS: After controlling for potentially confounding variables such as acromioplasty or preoperative fatty infiltration as well as muscle atrophy, the only morphological parameters associated with a higher risk (adjusted odds ratio) of SSP tendon rerupture were the acromiohumeral interval (adjusted OR 0.9 [95% CI 0.9 to 0.99]; p < 0.01) and acromial slope (adjusted OR 1.4 [95% CI 1.1 to 1.8]; p < 0.01). The critical shoulder angle, acromial tilt, acromial index, and lateral acromial angle were not associated with the risk of rerupture. The cutoff values for acromial slope and acromiohumeral interval were 24.5° and 7.4 mm, respectively. Patients with an acromiohumeral interval smaller than 7.4 mm or an acromial slope greater than 24.5° had higher odds (acromiohumeral interval: OR 11 [95% CI 2 to 46]; p = 0.01 and acromial slope: OR 9 [95% CI 2 to 46]; p = 0.04) for rerupture of the SSP. No difference was found between patients with intact SSP tendons and those with reruptured SSP tendons in terms of glenoid inclination (6° ± 4° versus 6° ± 3°, mean difference 0.8° [-1° to 3°]; p < 0.48) and glenoid version (-2° ± 3° versus -3° ± 3°, mean difference 1° [-1° to 3°]; p < 0.30). No difference was found between the intact and reruptured SSP groups regarding clinical outcomes (Western Ontario Rotator Cuff Index: 98 ± 2 versus 97 ± 3, mean difference 0.73 [95% CI -0.30 to 0.31]; p = 0.96; Oxford Shoulder Score: 26 ± 13 versus 23 ± 10, mean difference 2.80 [95% CI -4.12 to 9.72]; p = 0.41). CONCLUSION: The preoperative acromiohumeral interval and acromial slope are associated with SSP tendon rerupture after repair. Conversely, the critical shoulder angle, acromial tilt, lateral acromial angle, and acromial index had no association with the postoperative outcome. Additionally, glenoid inclination and version were not associated with the rerupture rate after SSP tendon repair. A detailed analysis of the acromiohumeral interval and acromial slope is recommended in clinical practice in patients undergoing SSP tendon repair. Surgeons should consider measuring the acromiohumeral interval and acromial slope preoperatively when performing SSP repair, especially in the context of planned acromioplasties. Future studies should investigate the role of acromioplasty during SSP repair in patients with a pathologic acromial slope and acromiohumeral interval. In this context, it should be determined whether a more-radical acromioplasty could reduce the risk of rerupture of the SSP in these patients. LEVEL OF EVIDENCE: Level III, therapeutic study.