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PubMedDate not supplied

Shape of the acromion: congenital or acquired--a macroscopic, radiographic, and microscopic study of acromion.

Debate continues as to whether the differing shapes of the acromion are congenital or acquired. This has been investigated by neonatal cadaver study, adult cadaver study, radiographic study, magnetic resonance imaging study, or various other means. No one, to our knowledge, has investigated this by histologic study. A macroscopic and histologic study of 22 cadaveric shoulder joints was carried out to establish what, if any, developmental changes occur in the differing patterns of acromion. The cadaveric shoulders were dissected and examined macroscopically. All of the acromion processes were transected and photographed, and the histology of the anterior and inferior surfaces was studied. In all of the curved and hooked types of acromion, a common pattern of degeneration of collagen, fibrocartilage, and bone was observed, consistent with a traction phenomenon. None of the flat acromions exhibited these changes. Extensive histologic changes were noted on the anterior surface of acromion as compared to the inferior surface in curved or hooked acromion. We conclude that the different shapes of acromion are, therefore, acquired as a response to traction forces applied via the coracoacromial ligament and are not congenital in origin.

Acromion↗
PubMedDate not supplied

Multiplanar analysis of acromion morphology.

To more completely describe acromion morphology and its relationship to impingement syndrome, we performed three-dimensional magnetic resonance imaging (N = 111) or computed tomography (N = 27) on 132 symptomatic shoulders. The mean patient age was 46.2 years (range, 14 to 86). Four parameters were evaluated: the angle of anterior slope of the acromion in the midsagittal and lateral-sagittal planes, lateral acromial angulation in the coronal plane, and the presence or absence of medial encroachment in the acromioclavicular joint. Twenty-five asymptomatic age-matched shoulders were used as controls. All imaging data were combined because no significant differences existed between the two imaging techniques. The mean acromion angle was 19.4 degrees in the midsagittal plane and 20 degrees in the lateral-sagittal plane. In the coronal plane, 97 (73%) acromions were neutral and 35 (27%) were downward sloping. Medial encroachment was present in 31 (24%) shoulders. Age distribution from the 2nd to 8th decade demonstrated a consistent and gradual transition from a flat acromion in the younger decades to a more hooked acromion in the older decades that was significant in both the midsagittal and lateral-sagittal planes. Furthermore, a greater percentage of patients were found to have downward angulating acromions with increasing age. Ninety-eight patients (74%) had stage II or III impingement. Of these shoulders, 39 (40%) had type I acromions, 51 (52%) type II, and 8 (8%) type III. Twenty-eight of 33 acromions with coronal lateral downward sloping had impingement, and all 31 shoulders with medial encroachment had impingement.

Acromion↗
PubMedDate not supplied

Relationship between the lateral acromion angle and rotator cuff disease.

One hundred consecutive magnetic resonance imaging (MRI) studies of the shoulder obtained for the purpose of evaluating rotator cuff symptoms were retrospectively reviewed to assess the relationship between acromion morphologic appearance and rotator cuff disease. The studies were reviewed simultaneously by two authors. Each cuff was assigned a tendon grade and an overall cuff score with MRI criteria previously described in the literature. A newly described "lateral acromion angle" was measured from a specified oblique coronal cut on each MRI study and was correlated with the corresponding MRI-determined rotator cuff score and supraspinatus tendon grade. Observed correlations were analyzed by using statistical methods. The average measured lateral acromion angle was 78 degrees, with a range from 64 degrees to 99 degrees. Eight shoulders had angles less than or equal to 70 degrees, and all eight of these patients were found to have full-thickness rotator cuff tears. As the lateral acromion angle decreased, a statistically significant increase in rotator cuff disease was noted (p < 0.0001). A significant correlation between increasing age and rotator cuff disease was also observed (p < 0.0001). Multiple regression analysis confirmed that both the lateral acromion angle and the age of the patient were independent predictors of rotator cuff score. Finally, although a trend was noted suggesting a correlation between acromion type (I--flat, II--curved, and III--hooked) and MRI-determined rotator cuff disease, this trend did not reach statistical significance (p = 0.12). Surgical correlation with MRI rotator cuff findings in 35 patients showed an MRI sensitivity of 100% and specificity of 83%. A statistically significant correlation between the lateral acromion angle and MRI-determined rotator cuff disease has been noted. The described angle may be a useful adjuvant in the evaluation and management of rotator cuff disease.

Acromioclavicular Joint↗
PubMed1997

Anatomy of the normal acromion investigated using MRI.

The shape of the acromion is strongly associated with impingement syndrome and with rotator cuff tears. It is notoriously difficult to image the acromion with conventional radiography. We have developed MRI techniques to depict the acromion in its longitudinal axis. Furthermore, we have measured the subacromial space in both external and internal rotation. In previous studies, three types of acromial shape have been described with the type III or hooked acromion being present in 66% of cases with rotator cuff tears. We studied 31 normal shoulders in 29 people using MRI. Within this population aged 24-36 years, mean age 31 years, no type III acromions were found. Twenty-one were type I (67.7%) and 10 were type II (32.3%). In addition, we found no difference in subacromial height in external or internal rotation. Low rates of intra- and interobserver error were found. These results imply that the hooked acromion is not present in the normal population and is, therefore, likely to be an acquired abnormality.

Acromion↗
PubMed1996

Lateral down-sloping of the acromion: a useful MR sign?

OBJECTIVE: The anterior acromion may appear to slope downward in a lateral direction on coronal-oblique magnetic resonance (MR) images of the shoulder. We sought to determine the significance of this finding as a marker of rotator cuff impingement. PATIENTS AND METHODS: MR studies of 58 subjects (26 with impingement, 32 with glenohumeral instability) were retrospectively analysed. Subjective down-sloping of the acromion was compared to standardized acromial measurements made on MR (acromial axis, width of the anterior acromion, and distance of the acromioclavicular joint from the superior glenoid) and clinical diagnosis. RESULTS: Interobserver variance for lateral down-sloping was fair (kappa = 0.5). One reader's assessment of lateral down-sloping of the acromion correlated with standardized MR measurements. Subjective lateral down-sloping of the acromion did not, however, correlate with impingement. CONCLUSION: The subjective finding of a laterally down-sloping acromion on coronal-oblique MR images, while partially validated by standardized measurements, is not predictive of impingement syndrome.

Acromion↗
PubMed1998

The relationship of the axillary nerve and the acromion.

The relationship of the axillary nerve in 77 cadavers was studied. The distance of the axillary nerve from the angle of the acromion is between 43 to 82 mm (mean = 63 mm). The distance from the axillary nerve to the tip of the acromion varies from 47 to 89 mm (mean = 67 mm). The distance in the female is less than that in the male. The length of the acromion and of the arm are not correlated with the distance between the axillary nerve and the acromion. In addition, the course of the axillary nerve is not constantly parallel to the lateral border of the acromion. Therefore, the acromion is not a good surgical landmark for locating the axillary nerve.

Acromion↗
PubMed1998

[Lifting osteotomy of the acromion as a new principle in treatment of impingement syndrome, especially in correlation with reconstruction of large rotator cuff lesions].

There are many different causes leading to impingement lesions of the shoulder (e.g., architecture of the acromion, arthritis of the acromioclavicular joint, bursitis subacromialis, chronic instability). There are also different ways of treating it. Neer described his technique of anterior acromioplasty in 1972. With this technique there is sometimes a limitation in the amount of resection possible because of the anatomical findings (i.e., very curved or small acromion). We developed a new technique: the lift-up osteotomy of the acromion (LOA). This technique allows us to gain as much subacromial space as needed (e.g., for large anterior deltoid flaps). Osteotomy of the acromion gives an excellent view of the rotator cuff. Even large lesions can easily be repaired. After the cuff repair is done, the acromion is refixed with two canulated screws. So far, we have used this LOA technique in more than 100 patients in impingement operations, cuff repairs and anterior deltoid flaps all with good results.

Acromion↗
PubMed2001

Acromion reconstruction after total arthroscopic acromionectomy: Salvage procedure using a bone graft.

We report 2 cases of acromion reconstruction with a bone graft as a salvage procedure after total arthroscopic acromionectomy. Complete removal of the acromion had produced severe shoulder abnormality with pain and joint stiffness. We present the operative technique of acromion reconstruction using a corticocancellous bone graft from the iliac crest. Recreation of the acromion as a fulcrum of the shoulder joint as well as an important physiological insertion area for the deltoid muscle markedly improved pain and range of motion in these patients. In conclusion, based on these cases, we believe that total acromionectomy is an inadequate procedure for treatment of shoulder impingement syndrome. Acromion reconstruction with a bone graft is an alternative that may lead to improvement of clinical symptoms.

Acromion↗
PubMed1993

Hooked acromion: prevalence on MR images of painful shoulders.

An association between the morphology of the acromion and the occurrence of rotator cuff tear (RCT) has been suggested by findings at both pathologic examination and routine radiography. As a tomographic technique, magnetic resonance (MR) assessment of acromial shape may be more accurate than routine radiography. The authors studied acromial morphology on sagittal oblique MR images of a control population (47 shoulders), of patients with isolated impingement (30 shoulders), and of patients with full-thickness RCTs (34 shoulders) to assess the association of acromial shape with disorders of the rotator cuff. Acromions were classified as flat (type 1), smoothly curved (type 2), or hooked (type 3). Data were collected by two observers, blinded to clinical and surgical information, who acted in consensus. Patients with RCT had a significantly increased prevalence of type 3 acromions compared with control patients (62% vs 13%, P < .001). Type 3 acromions tended to be more prevalent in the group with impingement (30%, P = .17). There was no significant difference in the distribution of acromion types among control patients with respect to age or gender.

Acromion↗
PubMed1997

Acromion-splitting approach through an os acromiale for repair of a massive rotator cuff tear.

Os acromiale, failure of fusion of the secondary centers of ossification of the acromion process, has been noted as a contributing factor in shoulder impingement syndrome and rotator cuff tears. Treatments for symptomatic os acromiale with or without rotator cuff tears have been reported in the literature and range from excision of small fragments to fusion of larger, fragments with internal fixation and bone grafting. Generally, rotator cuff repairs have been performed when possible. We report an acromion splitting approach through an existing os acromiale to gain exposure for the repair of a massive rotator cuff tear. Subsequent to this repair, the acromion was repaired with internal fixation. Good functional use of the patient's upper extremity was obtained and the patient expressed satisfaction with the surgical outcome. The acromion splitting approach is a viable approach in patients with an os acromiale and a coexistent rotator cuff tear.

Acromion↗
PubMedDate not supplied

Fractures of the acromion and the lateral scapular spine.

We studied 37 fractures lateral to the spinoglenoidal notch to evaluate the validity of collectively handling these fractures as an acromion fracture and to ascertain the mechanism of injury. We divided them into three groups according to the location of the fracture line. Fracture of the anatomic acromion or the extremely lateral scapular spine (groups I and II, 28 fractures) was frequently associated with fracture of the coracoid base, acromioclavicular joint injury, or both. The mechanism of injury in most cases was presumed to be indirect force brought to bear on the shoulder from the lateral direction. Fracture descending to the spinoglenoidal notch (group III, nine fractures) was seldom associated with other shoulder injuries, and surgery was rarely needed. The mechanism was assumed to be direct force brought to bear on the shoulder from the posterior direction. Therefore fractures of the anatomic acromion and the extremely lateral scapular spine may be managed collectively. However, fracture descending to the spinoglenoidal notch should be managed separately. We advocate that these fractures should be classified into two types in terms of clinical consideration: type I fractures, comprising those of the anatomic acromion and the extremely lateral scapular spine, and type II fractures, located in the more medial spine and descending to the spinoglenoidal notch.

Acromion↗
PubMed2000

Radiographic evaluation of the acromion in impingement syndrome: comparison with arthroscopic findings in 147 shoulders.

We analyzed standardized scapulolateral and anteroposterior view radiographs in 147 patients with impingement syndrome to detect a subacromial osteophyte or spur, which should be of value in those patients who require surgical treatment. Standard anteroposterior view radiographs with a fixed tube angulation, 0 and 30 degrees, were compared to anteroposterior view radiographs with individual tube angulation (the radiograph beam was tilted caudally, depending on the slope of the acromion). In all patients, we identified an acromion bony overhang on the anteroposterior view radiographs with individual tube angulation having an average thickness of 5 mm, which correlated well with the intraoperative findings at arthroscopic acromioplasty. In only 35% of the patients did we detect a subacromial osteophyte or spur on radiographs with a fixed tube at 0 degrees angulation and in 92%, we found a false impression of a spur on the 30-degree views because of overexposure. We conclude that, anteroposterior view radiographs with an individual caudally-tilted X-ray beam, depending on the acromion slope, can show the whole spur and/ or size of the osteophyte, on the anterior margin of the acromion.

Acromion↗
PubMedDate not supplied

Excursion of the rotator cuff under the acromion. Patterns of subacromial contact.

Nine fresh-frozen, human cadaveric shoulders were elevated in the scapular plane in two different humeral rotations by applying forces along action lines of rotator cuff and deltoid muscles. Stereophotogrammetry determined possible regions of subacromial contact using a proximity criterion; radiographs measured acromiohumeral interval and position of greater tuberosity. Contact starts at the anterolateral edge of the acromion at 0 degrees of elevation; it shifts medially with arm elevation. On the humeral surface, contact shifts from proximal to distal on the supraspinatus tendon with arm elevation. When external rotation is decreased, distal and posterior shift in contact is noted. Acromial undersurface and rotator cuff tendons are in closest proximity between 60 degrees and 120 degrees of elevation; contact was consistently more pronounced for Type III acromions. Mean acromiohumeral interval was 11.1 mm at 0 degrees of elevation and decreased to 5.7 mm at 90 degrees, when greater tuberosity was closest to the acromion. Radiographs show bone-to-bone relationship; stereophotogrammetry assesses contact on soft tissues of the subacromial space. Contact centers on the supraspinatus insertion, suggesting altered excursion of the greater tuberosity may initially damage this rotator cuff region. Conditions limiting external rotation or elevation may also increase rotator cuff compression. Marked increase in contact with Type III acromions supports the role of anterior acromioplasty when clinically indicated, usually in older patients with primary impingement.

Acromion↗
PubMed2001

[Fracture of the acromion. Diagnosis--treatment strategy--outcome].

The case of an 22-year-old man is presented, who sustained a dislocated fracture of the left acromion process and a not dislocated fracture of the left scapular body with a large subcutaneous décollement as well as a dammage of nervus axillaris occurring during a traffic accident. After resuming diagnostics by means of CT, a tension banding of the ventral part of the acromion and a plate osteosynthesis of the dorsal part was performed. 7 weeks after injury neurolysis of nervus axillaris has been done. 4 months after accident the patient shows a satisfying functional result in the Constant score. Diagnostic, treatment and functional results after operative treatment of dislocated fractures of the acromion are shown and discussed.

Acromion↗
PubMedDate not supplied

Apophysitis of the acromion.

We treated three patients with apophysitis of the acromion. These patients were two male athletes 12 and 14 years of age, respectively, and one female athlete 13 years of age. They reported pain at the top of the shoulder during and after shoulder movement while playing sports but had no rest pain or disturbance of daily activities. Physical examination demonstrated marked local tenderness at the acromion and slight warmth. X-ray films showed sclerosis and irregularity of the secondary ossification center of the acromion. Bone scintigraphy carried out on one patient demonstrated increased uptake in that region. Conservative treatment was used for these patients. Recovery was gradual but satisfactory.

Acromion↗
PubMedDate not supplied

The acromion: morphologic condition and age-related changes. A study of 420 scapulas.

Two hundred ten specimens (420 scapulas) from the Hamann-Todd Osteological Collection at the Cleveland Museum of Natural History were evaluated to determine the influence of age on acromial morphologic condition. Equal numbers of specimens from female and male and black and white subjects were evaluated. The length, width, and anterior thickness of the acromion and the acromial facet of the acromioclavicular joint were measured with digital calipers, examined visually, and evaluated radiographically. Distribution of acromial morphologic types was type I, (flat) 32%, type II (curved), 42%, and type III (hooked), 26%. Analysis of the data revealed no consistent, statistically significant impact of age on morphologic condition. The incidence of os acromiale was 8% (17 of 210), with 7 (41%) of 17 specimens having bilateral involvement. Mean acromial dimensions in men were length = 48.5 mm, width = 19.5 mm, and anterior thickness = 7.7 mm. Mean dimensions in women were length = 40.6 mm, width = 18.4 mm, and thickness = 6.7 mm. Multiple regression analysis revealed no significant changes in any dimension with increasing age. Observation of the acromial facet of the acromioclavicular joint revealed 49% were medially inclined, 48% were vertically inclined, and only 3% were laterally inclined in relationship to the sagittal plane. A statistically significant age-related increase in degenerative changes was noted. Anterior acromial spur formation as determined by visual inspection of the acromion was observed in 7% of specimens from patients younger than 50 years compared with 30% of specimens from patients older than 50 years (p < 0.05). Spur formation on the anterior acromion is an age-dependent process. Acromial morphologic condition as evaluated by outlet radiographs is independent of age and appears to be a primary anatomic characteristic. The variations seen in acromial morphologic condition are not acquired from age-related changes and spur formation and thus contribute to impingement disease independent of and in addition to age-related processes.

Acromioclavicular Joint↗
PubMedDate not supplied

[Widening of the sub-acromial space using a wedge osteotomy of the scapular spine. Anatomical bases, measurements on the preparation, studies of the kinematics of the acromion movements on a computer model].

We describe the theoretical principles of a new kind of decompression of subacromial impingement syndrome by means of a wedge osteotomy at the transition between acromion and spine of the scapula. The operation on cadaver bone and the simulation of acromion movement in a computer model demonstrate an increase of subacromial space more than 1 cm after wedge excision with cranial base of 5 mm and ventral base of 3 mm. After the excision of an anterior based wedge the resection of the coracoacromial ligament is not necessary. An angle between 50 and 60 degrees from mediocranial to laterocaudal referred to the transverse plane has been calculated as optimal. We regard the sparing of the abducting parts of deltoid muscle, the better approach to the cuff with the possibility to mobilize the supraspinate muscle in cases of greater cuff-tears and the possibility to obtain a smooth undersurface of the acromion as further advantages of this procedure. Further biomechanic experiments will be necessary to optimize osteosynthesis.

Acromion↗
PubMed1994

Fractures of the acromion process: a proposed classification system.

A review of 27 fractures of the acromion process during a 15-year period revealed five distinct types that were classified into three groups. Stress fractures are rare, do not result from acute trauma, and gain little benefit from nonoperative treatment. Type I fractures are minimally displaced. Type IA fractures are avulsion fractures and heal rapidly. Type IB fractures result from direct trauma to the extremity, and are minimally displaced. Most heal with nonoperative treatment. Type II fractures are displaced laterally, superiorly or anteriorly and do not reduce the subacromial space. Most are pain free with full motion after 6 weeks of nonoperative treatment. Type III fractures reduce the subacromial space. This may occur by an inferiorly displaced acromion fracture, or an acromion fracture associated with an ipsilateral, superiorly displaced glenoid neck fracture. Patients in this group sustained significant trauma to the involved extremity. All type III fractures treated nonoperatively develop significant limited shoulder motion with pain, suggesting that early surgical intervention may be indicated.

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