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.

Anatomical Variants Identified on Computed Tomography of Oropharyngeal Carcinoma Patients.

Background and Objectives: Anatomical variations in the head, neck and chest are common, and are observed as occasional findings on computed tomography (CT). Although anatomical variations are mostly asymptomatic and do not cause any negative influence on the body function, they may jeopardize diagnosis and may be confused with pathological conditions. The presence of variations may also limit surgical access during tumor removal. The aim of this study was to investigate the prevalence of six anatomical variations-os acromiale, episternal ossicles, cervical rib, Stafne bone cavity, azygos lobe and tracheal bronchus-in an open-access computed tomography dataset obtained from oropharyngeal cancer patients. Materials and Methods: A total of 606 upper-chest and neck computed-tomography scans (79.4% male and 20.6% female) were retrospectively investigated. Sex difference was evaluated using the z-test for two proportions. Results: Os acromiale, episternal ossicles, cervical rib, Stafne bone cavity, azygos lobe, and tracheal bronchus were present in 3.1%, 2.2%, 0.2%, 0%, 0.3% and 0.5%, respectively, of all patients. Os acromiale was identified as meso-acromion in 86.6%, and as pre-acromion in 17.4%, of all acromia. Episternal ossicles were present unilaterally in 58.3%, and bilaterally in 41.7%, of all sterna. Only the cervical rib showed a sex difference in prevalence. Conclusions: awareness of these variations is important for radiologists interpreting head, neck and chest CTs; for example, those of oropharyngeal cancer patients. This study also illustrates the applicability of publicly available datasets in prevalence-based anatomical research. While most of the variations investigated in the present study are well-known, the episternal ossicles are not well explored, and need further investigation.

Anterolateral Acromioplasty Does Not Change the Critical Shoulder Angle and Acromion Index in a Clinically Relevant Amount.

PURPOSE: Assessment on whether radiographic parameters of the acromion measured in radiographs change significantly after anterolateral acromioplasty. METHODS: This retrospective study included patients that underwent an arthroscopic anterolateral acromioplasty between January 2014 and September 2020. n = 435 subjects with high-quality preoperative and postoperative radiographs according to Suter-Henninger criteria were included in the final assessment. All measurements were independently performed by the first and second author in a blinded fashion using dicomPACS software: acromion index (AI), critical shoulder angle (CSA), lateral acromial angle (LAA), beta angle, acromio-humeral distance (AHD), Aoki angle, frontal supraspinatus outlet angle (FSOW), and acromion type, according to Bigliani. SPSS software was used for statistical analysis. RESULTS: The beta angle and the CSA did not significantly change after operation (alpha power 0.32 and 0.11, respectively). In a subgroup analysis of patients with a pathological CSA >35° (n = 194), the CSA changed from 38.62 (range: 35.08-47.52, SD 2.83) to 38.04 (range: 29.18-48.12, SD 3.77) postoperatively (P = .028) (Fig 8). All other parameters changed significantly after operation (AI, AHD, FSOW, and Aoki; P = .001, LAA; P = .039) (Fig. 9). The interobserver and intraobserver reliability was good to excellent in the majority of measured values. Mean patient age was 59.2 years (range: 18.1-87.1; SD 11.3), mean height was 1.73 meters (range: 1,50-1.98, SD 0.09), mean weight was 80.2 kg (range: 37.0-133.0, SD 16.68), and mean body mass index was 26.6 (range: 0.0-46.1, SD 4.73). CONCLUSION: Anterolateral acromioplasty producing a flat acromion undersurface did not result in a significant change of the CSA in the study population. Pathological preoperative CSA values of >35° were significantly reduced but not to normal values, but only by a small amount that puts the clinical relevance into question. LEVEL OF EVIDENCE: IV, diagnostic study, case series.

Influence of Acromial Morphologic Characteristics and Acromioclavicular Arthrosis on the Effect of Platelet-Rich Plasma on Partial Tears of the Supraspinatus Tendon.

OBJECTIVE. The purposes of this study were to determine the medium-term effect of ultrasound-guided infiltration of platelet-rich plasma (PRP) on partial tears of the supraspinatus tendon (SST) and to identify prognostic indicators of an unfavorable outcome. SUBJECTS AND METHODS. Over a period of 4 years, patients with a partial SST tear smaller than 1.5 cm referred for ultrasound-guided PRP infiltration (1 mL) for shoulder pain lasting more than 3 months were recruited consecutively. MRI was used to analyze the type of acromion and presence of acromioclavicular (AC) arthrosis. Primary (size of the tear and associated bursitis) and secondary (mobility and pain) results were collected at 3 months. RESULTS. The study included 128 patients (66 men, 62 women; mean age, 48.3 years; range, 20-59 years). At 3 months, favorable evolution of the tear repair was recorded in 71.1% (91/128) of patients and resolution of bursitis in 66.7% (42/63). Changes in tear size had large effect sizes (Cohen d ≥ 1.16), as did pain and shoulder mobility (Cohen d ≥ 0.95). The strongest predictors of unfavorable evolution of tear and bursitis were type 3 acromion and types 1 and 2 acromion with AC arthrosis (p < 0.001; ß = 20.412). CONCLUSION. Ultrasound-guided PRP infiltration of partial tears of the SST relieves pain and improves shoulder mobility, but its effect on the size of the tear is influenced by the morphologic characteristics of the acromion and the presence of AC arthrosis. The effect of PRP is insufficient in patients with a type 3 acromion or severe AC arthrosis.

The value of radiographic markers in the diagnostic work-up of rotator cuff tears, an arthroscopic correlated study.

OBJECTIVE: To evaluate the value of radiographs during the diagnostic work-up of rotator cuff tears, using arthroscopy as reference standard. MATERIALS AND METHODS: This retrospective study included 236 shoulders of 236 patients. All radiographs were evaluated for inferior cortical acromial sclerosis, lateral acromial spur, superior migration of the humeral head, greater tubercle cysts, and subacromial space calcifications. Predictive value of these radiographic signs in predicting rotator cuff tears was determined with arthroscopy as reference standard. RESULTS: According to arthroscopy, 131 shoulders were diagnosed with rotator cuff tears. Seventy-two out of 131 shoulders (55%) had inferior cortical acromial sclerosis, 37 (28%) lateral acromial spur, 21 (16%) superior migration of the humeral head, 7 (5%) greater tubercle cysts and 15 subacromial space calcifications (11%). Inferior cortical acromial sclerosis (P = 0.001), lateral spur (P = 0.001), superior migration (P = 0.002), and cysts (P = 0.03) were significantly and independently associated with rotator cuff tears, whereas subacromial calcifications (p = 0.21) was not. Inferior cortical acromial sclerosis, superior migration, lateral acromial spur, and cysts combined have a positive predictive value of 78%. CONCLUSIONS: The combination of inferior cortical acromial sclerosis, lateral acromial spur, superior migration of the humeral head, and greater tubercle cysts has a high positive predictive value for the presence of full-thickness rotator cuff tears. In patients with a high suspicion for having a rotator cuff tear based on radiographic findings, MRI can be performed directly without the delay and costs caused by an additional ultrasound exam.

Where and what damage occurs at the acromial undersurface in patients with rotator cuff tears?

BACKGROUND: The gross pathology of the acromial undersurface in shoulders with rotator cuff tears with subacromial impingement is not completely understood. Many researchers have focused on damage to the anterior one-third area of the acromial undersurface, but few have studied the middle and posterior one-third areas. The purpose of this study was to clarify where and what damage occurs at the acromial undersurface in patients with rotator cuff tears. METHODS: We performed arthroscopic shoulder (n = 182, all with rotator cuff tears; mean age, 64.9 ± 8.4 years) and cadaveric shoulder (n = 23, 14 intact cuffs and 9 rotator cuff tears; mean age, 74.8 years) evaluations to observe the extent and degree of damage to the acromial undersurface. We statistically analyzed the association between the severity of the damage to the acromial undersurface (assessed using the Copeland-Levy classification as A0, normal; A1, minor scuffing; A2, major damage; or A3, visualization of bare bone area) and rotator cuff tear size (assessed using the classification of DeOrio and Cofield as partial; small, <1 cm; medium, 1-3 cm; or large or massive, >3 cm). RESULTS: The anterior, middle, and posterior one-thirds of the acromial undersurface were somewhat damaged (class A1-A3) in 92.6%, 90.1%, and 78.6% of shoulders with rotator cuff tears, respectively, according to arthroscopic evaluation. Increasing cuff tear size was significantly associated with worsening degree of damage to the acromial undersurface (P < .001). In the 9 cadaveric shoulders with rotator cuff tears, class A1-A3 damage was identified in the anterior one-third area in 100%, in the middle one-third area in 88.9%, and in the posterior one-third area in 33.3%. In the 14 cadaveric shoulders with a normal rotator cuff, class A1-A3 damage was identified in the anterior one-third area in 35.7%, in the middle one-third area in 14.3%, and in the posterior one-third area in 0.71%. CONCLUSION: Damage to the acromial undersurface in patients with rotator cuff tears occurred at the middle, posterior, and anterior one-third areas, and the degree of damage was related to cuff tear size. Surgeons should evaluate the entire acromial undersurface to check for subacromial impingement damage at the middle and posterior one-third areas as well as the anterior one-third area of the acromial undersurface; this might aid in the treatment of patients with rotator cuff disease or subacromial impingement syndrome.

Subacromial impingement anatomy and its association with rotator cuff pathology in women: radiograph and MRI correlation, a retrospective evaluation.

OBJECTIVE: To evaluate the relationships between acromial anatomy and developmental alterations with rotator cuff tears in female patients and compare these parameters on radiographs and corresponding MRIs along with inter-reader performance. MATERIALS AND METHODS: Patient demographics, symptoms, and acromial characteristics on radiograph (acromial index, lateral acromion angle, subacromial space on AP and Y- views, acromial anterior and lateral downsloping) and MRI (shape, slope, spur, osteoarthrosis, os acromiale) were recorded. Radiographic and MRI findings were compared and correlated with rotator cuff pathology on MRI. Inter-reader analysis was performed. RESULTS: A total of 140 MRIs from 137 female patients were included. No significant correlation (p > 0.05) existed between acromial parameters and rotator cuff tears, except for a smaller subacromial space on the Y view and spurs correlated with subscapularis tendon tear (p = 0.02, p = 0.04). The presence of lateral downsloping on MRI correlated with a smaller lateral acromion angle (p = 0.0002) and the presence of lateral downsloping on radiography (p = 0.0015). Inter-reader agreements were good to excellent (ICC: 0.65-0.89). CONCLUSION: Subacromial impingement anatomy characteristics have no significant associations with supraspinatus or infraspinatus tears in symptomatic women. Among different measures, supine MRI can be reliably used to identify lateral downsloping of the acromion.

The Effectiveness of Using the Critical Shoulder Angle and Acromion Index for Predicting Rotator Cuff Tears: Accurate Diagnosis Based on Standard and Nonstandard Anteroposterior Radiographs.

PURPOSE: To explore whether the critical shoulder angle (CSA) and acromion index (AI) on nonstandard anteroposterior (AP) radiographs could be used as parameters for rotator cuff tear (RCT) diagnosis and to determine the optimized parameters. METHODS: This study included 174 patients with RCTs or intact rotator cuffs in whom AP radiographs were obtained at our hospital. The radiographs were assessed by 2 independent radiologists and were grouped according to the Suter-Henninger criteria. The CSA and AI were measured on all films. We performed receiver operating characteristic curve analysis by calculating the area under the curve (AUC) to compare the sensitivity and accuracy of both parameters. RESULTS: Of the 174 enrolled patients, only 47 (27%) met the requirements for standard AP films (types A1 and C1). On standard AP films, both the CSA and AI were significantly different between the RCT and control groups (P < .001 for CSA and P < .001 for AI), with AUCs of 0.86 and 0.80 for the CSA and AI, respectively. On nonstandard AP films (other radiograph types), the mean CSA value was not significantly different between the RCT and control groups (P = .536) whereas the AI showed a significant difference (P = .024). The AUCs were 0.57 for the CSA and 0.64 for the AI. CONCLUSIONS: On standard AP films, both the CSA and AI could predict rotator cuff disorders, and the CSA had a higher diagnostic accuracy than the AI. In contrast, on nonstandard AP films, the diagnostic efficacy of the AI was better than that of the CSA. On the basis of this study, we suggest an evaluation of the AP films of patients before diagnosis to confirm whether the AP films meet the criteria for standard AP films. LEVEL OF EVIDENCE: Level I, diagnostic study.

Coracoacromial morphology: a contributor to recurrent traumatic anterior glenohumeral instability?

BACKGROUND: Although scapular morphology contributes to glenohumeral osteoarthritis and rotator cuff disease, its role in traumatic glenohumeral instability remains unknown. We hypothesized that coracoacromial and glenoid morphology would differ between healthy subjects and patients with recurrent traumatic anterior shoulder instability. METHODS: Computed tomography scans of 31 cadaveric control scapulae and 54 scapulae of patients with recurrent traumatic anterior shoulder instability and Hill-Sachs lesions were 3-dimensionally reconstructed. Statistical shape modeling identified the modes of variation between the scapulae of both groups. Corresponding measurements quantified these modes in relation to the glenoid center (linear offset measures), defined by the best-fit circle of the inferior glenoid, or the glenoid center plane (angles), which bisects the glenoid longitudinally. Distances were normalized for glenoid size. RESULTS: Compared with controls, the unstable coracoids were shorter (P = .004), with a more superior and medial offset of the tip (mean difference [MD], 7 and 3 mm, respectively; P < .001) and an origin closer to the 12-o'clock position (MD, 6°; P < .001). The unstable scapular spines originated closer to the 9-o'clock position (MD, 4°; P = .012), and the unstable acromions were more vertically oriented (MD, 6°; P < .001). The unstable glenoids had an increased height-width index (MD, 0.04; P = .021), had a flatter anterior-posterior radius of curvature (MD, 77 mm; P < .001), and were more anteriorly tilted (MD, 5°; P = .005). CONCLUSIONS: Coracoacromial and glenoid anatomy differs between individuals with and without recurrent traumatic anterior shoulder instability. This pathologic anatomy is not addressed by current soft-tissue stabilization procedures and may contribute to instability recurrence.

Different acromial roof morphology in concentric and eccentric osteoarthritis of the shoulder: a multiplane reconstruction analysis of 105 shoulder computed tomography scans.

BACKGROUND: The pathomechanisms of eccentric osteoarthritis of the shoulder remain unclear. Although there is increasing evidence of bony differences between shoulders with rotator cuff tears and osteoarthritis, analogous differences have not been identified for primary concentric and eccentric osteoarthritis. This study examined the shape and orientation of the acromial roof as a potential risk factor for the development of posterior glenoid wear. METHODS: We analyzed computed tomography images of 105 shoulders with primary osteoarthritis. Based on the classification of Walch, 45 shoulders had concentric osteoarthritis (Walch A) and 60 shoulders were affected by eccentric osteoarthritis (Walch B; EOA). A comparison of acromial morphology was performed in a multiplanar reconstruction analysis of computed tomography scans. RESULTS: Acromial shape: Acromial length, width, and area were not significantly different. Acromial roof orientation: The acromial roof in EOA was an average of 5° flatter (sagittal tilt; P < .01) and 5° more downward tilted (coronal tilt; P < .01). There was no difference in axial rotation (axial tilt; P = .47). Anteroposterior glenoid coverage: The glenoid in EOA was covered an average of 4° less posteriorly (P = .01) and 4° more anteriorly (P = .04). No differences were shown for overall glenoid coverage. CONCLUSIONS: The acromial roof could play a role in the pathogenesis of EOA. Less posterior support due to a flatter acromion with less posterior glenoid coverage could contribute to static posterior subluxation of the humeral head and posterior glenoid wear. Further biomechanical investigations are needed to confirm these findings.

A simple method to directly evaluate the lateral extension of the acromion: an anatomic study of 128 cadaveric scapulae.

BACKGROUND: The lateral extension of the acromion from the glenohumeral joint is the critical variable that both the acromial index and critical shoulder angle reflect. The purpose of this study was to establish a simple and reproducible method to directly measure the lateral extension of the acromion that will be independent of patient demographic characteristics, scapular rotation, or other morphologic features of the shoulder. METHODS: This study used 128 unpaired cadaveric scapulae with a mean age of 69.4 ± 11.1 years (66 right and 62 left scapulae, 65 female and 63 male cadaveric specimens). The lateral extension of the acromion was measured from the supraglenoid tubercle to the most lateral point of the acromion with a digital caliper placed perpendicular to the scapula long axis. This distance was called the "lateral offset of the acromion." RESULTS: The lateral offset was 2.62 ± 0.72 cm in men and 2.69 ± 0.73 cm in women. The offset was 2.61 ± 0.66 cm in right and 2.70 ± 0.78 cm in left scapulae. The offset in the group aged 46-60 years was 2.85 ± 0.76 cm; in the group aged 61-75 years, it was 2.62 ± 0.76 cm; and in the group aged 76 years or older, it was 2.54 ± 0.60 cm. No significant difference was found between any of the groups. CONCLUSIONS: This study established a simple method to directly measure the lateral extension of the acromion based on the longitudinal axis of the scapula, which eliminates bias that may exist in the acromial index and critical shoulder angle from the position of the scapula and glenoid inclination. The lateral offset was found to be independent of sex, side, or age, limiting bias in a potential future clinical application.

Acromial roof in patients with concentric osteoarthritis and massive rotator cuff tears: multiplanar analysis of 115 computed tomography scans.

BACKGROUND: There is evidence for differences of scapular shape between shoulders with rotator cuff tears (RCT) and osteoarthritic shoulders (OA). This study analyzed orientation and shape of the acromion in patients with massive RCT and concentric OA (COA) in a multiplanar computed tomography (CT) analysis. METHODS: CT scans of 70 shoulders with degenerative RCT and 45 shoulders with COA undergoing primary shoulder arthroplasty were analyzed. The 2 groups were compared in relation of (1) shape of the acromion, (2) its orientation in space, and (3) the anteroposterior glenoid coverage in relation to the scapular plane. RESULTS: Lateral acromial roof extension was an average of 4.6 mm wider and the acromial area was an average of 156 mm2 larger in RCT than in COA (P < .001). Significant differences of the lateral extension of the acromion margin were limited to the anterior two-thirds. Acromial roof orientation in RCT was average of 10.8° more "externally rotated" (axial plane: P < .001) and an average of 7.8° more tilted downward (coronal plane: P < .001) than in COA. The glenoid in RCT was an average of 5.5° (P < .001) more covered posteriorly compared with COA. CONCLUSIONS: A more externally rotated (axial plane), more downward tilted (coronal plane), and wider posterior covering acromion was more frequent in patients with massive RCT than COA.

Morphological analysis of acromion and hook plate for the fixation of acromioclavicular joint dislocation.

PURPOSE: Acromioclavicular (AC) joint dislocation is a common sports injury. Hook plate fixation is currently widely used to treat this injury, as it can promote the natural healing of the ligament with good clinical outcomes. However, subacromial erosion and impingement are frequently observed post-operatively. It was hypothesized that the morphology and the contact characteristics between the hook portion and the acromion are the main causes of complications after hook plate fixation with the currently available commercial designs. METHODS: Three-dimensional reconstructed models of the AC joint obtained from the computed tomographic scans of 23 male and 23 female patients (mean age, 61.1 ± 6.3 years) were evaluated, and multiple anatomical parameters were measured. For the subacromial positioning of the hook plate, an actual hook plate (Synthes Inc., West Chester, PA, USA) was scanned, and the contact between the hook plate and the acromion was estimated. RESULTS: The thicknesses of the acromion and distal clavicle were 9.7 ± 1.5 mm (10.7 mm in men; 8.6 mm in women) and 11.3 ± 1.6 mm (11.6 mm in men; 10.0 mm in women), respectively. The width of the acromion was 28.5 ± 3.6 mm. The mean inclination angle between the hook plate and the acromion was 29.3° ± 9.7° (27.9° in men; 30.6° in women). The hook plate made a point contact with the acromion at 9.2 ± 3.3 mm (31.5 %) from the lateral end of the acromion. CONCLUSIONS: The results revealed that the hook made a pinpoint contact with the undersurface of the acromion, and this might explain why complications commonly occur after hook plate fixation. The force concentration phenomenon associated with the hook plate of existing designs results from cases of morphological mismatch, such as excessive inclination and improper occupation of the subacromial space.

The anterior borders of the clavicle and the acromion are not always aligned in the intact acromioclavicular joint: a cadaveric study.

BACKGROUND: The aim of this study was to find reliable anatomic landmarks of the normal acromioclavicular joint (ACJ) that could enable the precise evaluation of the horizontal displacement of the clavicle after dislocation. The hypothesis was that the anterior borders of the acromion and the clavicle are always aligned in intact ACJs. MATERIALS AND METHODS: In 30 cadaveric specimens, the anterior and posterior borders of the ACJ's articular facets and the most prominent anterior and posterior bony landmarks of the acromion and the clavicle were identified. The anterior and posterior overhang of the acromion and the clavicle was measured in relation to the borders of the articular facets. Therefore, the possible anterior and posterior alignment of the ACJ was evaluated. RESULTS: Anteriorly, only 18 ACJs (60%) were aligned whereas 7 (24%) had major overhang of the acromion and 3 (10%) had major overhang of the clavicle. Similarly, 18 cases (60%) were posteriorly aligned, whereas 6 (20%) had major clavicular overhang and 4 (14%) had major overhang of the acromion. In 78% of these cases, the ACJ was aligned as well anteriorly as posteriorly (P < .001). Finally, the larger the width of the acromion (P = .032) or the clavicle (P = .049), the better the posterior joint alignment. CONCLUSION: Our hypothesis was not verified. The acromion and clavicle are not perfectly aligned in a significant number of specimens with intact ACJs (40% of cases). The most reliable landmarks remain their articular facets.

Acromial apophysiolysis: superior shoulder pain and acromial nonfusion in the young throwing athlete.

PURPOSE: To describe the frequency of acromial apophysiolysis and its association with incomplete fusion and superior shoulder pain, to determine risk factors of acromial apophysiolysis, and to assess whether acromial apophysiolysis is associated with the development of an os acromiale and rotator cuff tears. MATERIALS AND METHODS: Institutional review board approval was obtained for this HIPAA-compliant study; requirement for informed consent was waived. A retrospective report review of 2372 consecutive patients between 15 and 25 years of age who underwent shoulder magnetic resonance (MR) imaging for shoulder pain was performed. Individuals with edema at the acromial apophyses and no other abnormalities on MR images were included in the study group. Association of acromial edema with incomplete fusion, pitching, and clinical findings was determined in the study group and in an age- and sex-matched control group, with both univariate and multivariate binary logistic regression analyses. Association with the development of an os acromiale and rotator cuff tears later in life was assessed with follow-up imaging after age 25 years. RESULTS: Edema at the acromial apophyses was found in 2.6% (61 of 2372) of patients and was associated with incomplete fusion of the acromial apophyses (χ(2), P < .001) and superior shoulder tenderness (P < .001). The entity was named acromial apophysiolysis. A pitch count of more than 100 pitches per week was shown to be a risk factor for acromial apophysiolysis (odds ratio [ OR odds ratio ] = 6.5, P = .017). Follow-up imaging showed that acromial apophysiolysis was significantly associated with the development of an os acromiale ( OR odds ratio = 138, P < .001) and rotator cuff tears ( OR odds ratio = 5.4, P = .015) after age 25 years. CONCLUSION: Acromial apophysiolysis is characterized by incomplete fusion and edema at the acromial apophyses. It is associated with superior shoulder pain in young patients (< 25 years old), and pitching is a risk factor. It predisposes the patient to the development of an os acromiale and rotator cuff tears after age 25 years.

Differentiating os acromiale from normally developing acromial ossification centers using magnetic resonance imaging.

OBJECTIVE: Acromial fusion may not be complete until age 18-25, making it questionable to diagnose os acromiale in adolescents. Os acromiale may exist in adolescents and can be differentiated from a developing acromial ossification center based on MRI findings. MATERIALS AND METHODS: A total of 128 MRIs of the shoulder were randomly and blindly reviewed retrospectively by two musculoskeletal radiologists. The MRIs consisted of two groups: (1) 56 of os acromiale in adults (25-74 years old, mean, 50) and (2) 72 consecutive of adolescents (12-17 years old, mean, 14.5). The following were assessed at the interface between the distal acromion and os acromiale/developing ossification center(s): presence of os acromiale vs. developing acromion, orientation, margins, and edema within and adjacent to it. RESULTS: Fifty-one adults and 49 adolescents were included. Exclusions were due to poor image quality or confounding findings (n = 7) or complete acromial fusion (n = 21 adolescents). Utilizing accepted definitions of os acromiale, all adult cases (100 %) were accurately diagnosed as os acromiale, with transverse interface orientation and irregular margins (94 %, R = 0.86, p < 0.00001). Forty-five (92 %) adolescent cases were accurately diagnosed as normally developing acromion with arched interface and lobulated margins (92 %, R = 0.92, p < 0.000001). Four (8 %) adolescent cases were diagnosed as having os acromiale, with transverse orientation and irregular margins. Thirty-five (69 %) and 46 (90 %) adults had marrow and interface edema, respectively. Six (12 %) and eight (16 %) adolescents had marrow and interface edema, respectively, including the four concluded to be os acromiale. CONCLUSIONS: Adolescents may have imaging findings consistent with os acromiale. The diagnosis of os acromiale should be based on imaging features and not limited by age.

Acromiohumeral distance measurement in rotator cuff tendinopathy: is there a reliable, clinically applicable method? A systematic review.

BACKGROUND: Narrowing of the subacromial space has been noted as a common feature of rotator cuff (RC) tendinopathy. It has been implicated in the development of symptoms and forms the basis for some surgical and rehabilitation approaches. Various radiological methods have been used to measure the subacromial space, which is represented by a two-dimensional measurement of acromiohumeral distance (AHD). A reliable method of measurement could be used to assess the impact of rehabilitation or surgical interventions for RC tendinopathy; however, there are no published reviews assessing the reliability of AHD measurement. OBJECTIVES: The aim of this review was to systematically assess the evidence for the intrarater and inter-rater reliability of radiological methods of measuring AHD, in order to identify the most reliable method for use in RC tendinopathy. STUDY APPRAISAL AND SYNTHESIS: An electronic literature search was carried out and studies describing the reliability of any radiological method of measuring AHD in either healthy or RC tendinopathy groups were included. Eighteen studies met the inclusion criteria and were appraised by two reviewers using the Quality Appraisal for reliability Studies checklist. RESULTS: Eight studies were deemed to be of high methodological quality. Study weaknesses included lack of tester blinding, inadequate description of tester experience, lack of inclusion of symptomatic populations, poor reporting of statistical methods and unclear diagnosis. There was strong evidence for the reliability of ultrasound for measuring AHD, with moderate evidence for MRI and CT measures and conflicting evidence for radiographic methods. Overall, there was lack of research in RC tendinopathy populations, with only six studies including participants with shoulder pain. CONCLUSIONS: The results support the reliability of ultrasound and CT or MRI for the measurement of AHD; however, more studies in symptomatic populations are required. The reliability of AHD measurement using radiographs has not been supported by the studies reviewed.

Role of sonography and magnetic resonance imaging in detecting deltoideal acromial enthesopathy: an early finding in the diagnosis of spondyloarthritis and an under-recognized cause of posterior shoulder pain.

The acromial origin of the deltoid is a target structure of ankylosing spondylitis and related spondyloarthritis, which are often overlooked and underdiagnosed as causes of posterior shoulder pain. The objective of this article is to review the roles of sonography and magnetic resonance imaging in detecting deltoideal acromial enthesopathy and their importance for optimizing management in individuals with posterior shoulder pain. Adequate awareness of such enthesopathy as a potential manifestation of inflammatory rheumatic disorders is critical for early diagnosis of spondyloarthritis.

Knot impingement after rotator cuff repair: is it real?

PURPOSE: The purpose of this study was to compare morphologic features of the acromion after 2 different repair methods (single-row [SR] repair with a minimum of 4 knots and suture-bridge [SB] repair with minimal knots) in medium to large rotator cuff tears. METHODS: From May 2005 to July 2012, 1,693 rotator cuff repairs were performed, among them medium to large tears requiring more than 2 anchors for repair; those who had 6-month postoperative magnetic resonance imaging (MRI) scans were included (221 shoulders). They were divided into 2 groups; group A (SR repair) and group B (SB repair). Acromial morphologic characteristics were evaluated using MRI 6 months postoperatively. An acromial defect was defined as an irregular defect or erosion on the flat acromion. Clinical measurements were performed using the American Shoulder and Elbow Surgeons (ASES) score, Constant score, visual analogue scale (VAS) pain score, and range of motion (ROM). RESULTS: Erosion in the acromion was observed in 2 of 118 patients (1.7%) in group A and in 1 of 103 (1%) patients in group B. There was no statistically significant difference between the 2 groups (P = .796). A statistically significant improvement was observed in the clinical scores measured (P = .0043). ROM was not fully recovered to the preoperative level at 6 months postoperatively. Acromioplasty was performed in 2 of 3 patients with acromial erosion. There was acromial erosion in one patient in group A without performing subacromial decompression. CONCLUSIONS: Our study showed that there was no difference in acromial erosion in high-profile knots made by an SR compared with double-row (DR) SB low-profile repairs. LEVEL OF EVIDENCE: Level III, retrospective comparative study.

Acromial morphology in patients with calcific tendinitis of the shoulder.

PURPOSE: The purpose of this study was to evaluate whether the morphology of the acromion in calcific tendinitis differs from controls without subacromial pathology and matches subacromial impingement. METHODS: Digital radiographs of 150 shoulders were evaluated with the open source DICOM-Viewer OsiriX. 50 patients had symptomatic calcific tendinitis of the shoulder, 50 had subacromial impingement without calcifications or rotator cuff tears, 50 with bruised shoulder that were previously asymptomatic served as controls. Acromial shape according to Bigliani et al. acromial tilt (AT) according to Kitay et al. and Aoki et al. acromion index (AI) according to Nyffeler et al. and lateral acromial angle (LAA) according to Banas et al. were measured. RESULTS: Both calcific (0.72; P = 0.001) and impingement groups (0.73; P = 0.008) were significantly different from controls (0.67) using AI measure, while only the calcific group (79.5°) was different from controls (84.1°) using LAA (P < 0.001), and only the impingement group (32.9°) was different from controls (29.2°) using AT (P < 0.001). An LAA <70° only occurred in two patients with calcific tendinitis. CONCLUSION: The hypothesis of this study was that the morphology of the acromion in calcific tendinitis differs from controls without subacromial pathology and matches subacromial impingement was only confirmed for the AI. The AI of shoulders with calcific tendinitis is comparable to that of shoulders with subacromial impingement.