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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↗
PubMed2005

Reliability and comparison of acromion assessment techniques on X-ray and magnetic resonance imaging (reliability of acromion assessment techniques).

OBJECTIVE: To determine the reliability and correlation of plain radiography and magnetic resonance imaging (MRI) in the assessment of acromion morphology. MATERIALS AND METHODS: Acromion morphology was assessed using the lateral acromion angle (LAA) and the acromion-humeral interval (AHI). Thirty patients who had X-rays and MRI for impingement syndrome were included. Six blinded observers assessed the acromion morphology subjectively and objectively. RESULTS: Neither acromion assessment technique demonstrated a positive correlation (kappa and intraclass coefficient < 0.55) between X-ray and MRI. Both techniques were reliable (kappa and intraclass coefficient > 0.55) when measured objectively by experienced observers. CONCLUSION: The LAA and the AHI are both reliable acromion assessment techniques on X-ray and MRI when measured objectively and by experienced observers.

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↗
PubMed2004

[The shape of the acromion and its effect on the subacromial space].

PURPOSE OF THE STUDY: A great variability of the shape of acromion exists in the population. The shape of the acromion plays a great role in development of the pathology of the subacromial space. Quantification of the anatomical changes using radiological examination (X-ray. CT) is a major contribution to the diagnosis of the subacromial space disorders and to differential diagnosis of painful affections of the shoulder. The aim of the study was to assess the prevalence of the degenerative changes in the subacromial space and their relation to the shape of the inferior space of acromion in our population. MATERIAL AND METHODS: In 50 randomly chosen cadavers during autopsy both shoulders where surgically explored in order to evaluate the changes on the rotator cuff and the changes on the major tubercule, on the tendon of the long head of biceps brachii in correlation to the shape of the inferior surface of acromion. RESULTS: Rotator cuff lesions of variable size were found in 16 cadavers, in 10 cases the lesion was unilateral, in 6 cases bilateral. The lesions were more often seen in the older age group. With increasing concavity of the inferior surface of acromion not only the number of the rotator cuff lesions and degenerative changes in the subacromial space were increasing, but so was the amount of the changes. CONCLUSION: The shape of acromion and increasing concavity plays a major role in the development of the subacromial pathology, accelerate the degenerative changes in this space. Reshaping the undersurface of acromion and diminishing the concavity in first stages of clinical symptoms, which present mostly as impingement syndrome, is reasonable to prevent larger pathological deterioration in subacromial space. The authors conclude that according to the relation between the shape of the inferior surface of acromion and the amount of lesion an early operative procedure is valuable.

Acromion↗
PubMed2007

Correlation between the four types of acromion and the existence of enthesophytes: a study on 423 dried scapulas and review of the literature.

The purpose of this study was to correlate the four types of acromial shape with the existence of enthesophytes, which together comprise two important parameters for subacromial impingement syndrome and rotator cuff tears. In addition, a review of the literature was carried out. Four hundred twenty-three dried scapulas were studied at the Department of Anatomy in the University of Cologne, Germany. Four types of acromion were found: the three classical ones as described by Bigliani et al. ([1986] Orthop Trans 10:216) and a fourth one, where the middle third of the undersurface of acromion was convex (Gagey et al. [1993] Surg Radiol Anat 15:63-70). The correlation between the four types of acromion and the presence of enthesophytes at its anterior undersurface was also recorded. The distribution of acromial types was as follows: type I, flat, 51 (12.1%); type II, curved, 239 (56.5%); type III, hooked, 122 (28.8%); and type IV, convex, 11 (2.6%). Enthesophytes were found in 1 of type I (2%), in 19 of type II (7.9%), in 46 of type III (37.7%), and in 0 (0%) of type IV acromions. Overall, 66 (15.6%) out of 423 scapulas had enthesophytes. In all cases, they were localized at the site of the coracoacromial ligament insertion on the acromion. Enthesophytes were significantly (P < 0.05) more common in type III acromions and this combination is particularly associated with subacromial impingement syndrome and rotator cuff tears. In type I and in type IV acromions, the incidence of enthesophytes is very small and, according to other studies, with these two acromial types rotator cuff tears are also rare.

Acromion↗
PubMedDate not supplied

Radiographic analysis of the acromion in the loose shoulder.

To investigate the contribution of bony stability to the pathogenesis of the loose shoulder, geometric parameters of the acromion by use of cineradiography were evaluated in patients with a loose shoulder and compared with those in the normal shoulder. One hundred twenty healthy individuals and eighty-two patients were enrolled. To evaluate the size of the acromion and the coverage of the humeral head by the acromion, the anterior width of the acromion and three angle parameters were measured. The findings demonstrated that the loose shoulder had a relatively smaller and more upwardly inclined acromion that was against the glenoid and provided less coverage of the humeral head. These characteristics of the acromion may contribute to the hypermobility and functional instability of the shoulder joint observed in patients with a loose shoulder. Therefore, a radiographic evaluation of the geometry of the acromion is important to determine the pathogenesis of the loose shoulder.

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↗
PubMed2006

Association of a large lateral extension of the acromion with rotator cuff tears.

BACKGROUND: Factors predisposing to tearing of the rotator cuff are poorly understood. We have observed that the acromion of patients with a rotator cuff tear very often appears large on anteroposterior radiographs or during surgery. The purpose of this study was to quantify the lateral extension of the acromion in patients with a full-thickness rotator cuff tear and in patients with an intact rotator cuff. METHODS: The lateral extension of the acromion was assessed on true anteroposterior radiographs made with the arm in neutral rotation. The distance from the glenoid plane to the lateral border of the acromion was divided by the distance from the glenoid plane to the lateral aspect of the humeral head to calculate the acromion index. This index was determined in a group of 102 patients (average age, 65.0 years) with a proven full-thickness rotator cuff tear, in an age and gender-matched group of forty-seven patients (average age, 63.7 years) with osteoarthritis of the shoulder and an intact rotator cuff, and in an age and gender-matched control group of seventy volunteers (average age, 64.4 years) with an intact rotator cuff as demonstrated by ultrasonography. RESULTS: The average acromion index (and standard deviation) was 0.73 +/- 0.06 in the shoulders with a full-thickness tear, 0.60 +/- 0.08 in those with osteoarthritis and an intact rotator cuff, and 0.64 +/- 0.06 in the asymptomatic, normal shoulders with an intact rotator cuff. The difference between the index in the shoulders with a full-thickness supraspinatus tear and the index in those with an intact rotator cuff was highly significant (p < 0.0001). CONCLUSIONS: A large lateral extension of the acromion appears to be associated with full-thickness tearing of the rotator cuff.

Acromion↗
PubMed2005

[Arthroscopic evaluation of the mobility of the meso-acromion].

OBJECTIVES: Failure of fusion of the secondary centers of ossification of the acromial apophyses is a pathology that should be included in the differential diagnosis of shoulder pain and subacromial impingement syndrome. Mobility of the meso-acromion is of particular importance in choosing the appropriate treatment. This study presents a new arthroscopic method to evaluate the mobility of os acromiale. METHODS: We presented the arthroscopic evaluation and surgical treatment of three women (mean age 43.3 years; range 34 to 53 years) with shoulder pain and a radiographically confirmed meso-acromiale. The Neer and Hawkins impingement signs were positive and palpation over the acromion gave rise to pain. Axillary radiographs showed a meso-acromion in all the affected shoulders. Magnetic resonance imaging showed a rotator cuff tear in one patient. During arthroscopic examination the motility of the meso-acromion was dynamically observed in the subacromial region and the rotator cuff tear was repaired. Acromioplasty was not performed. Following removal of pseudarthrotic areas, the mobile meso-acromion was fixed with a cerclage wire, two cannulated screws and bone grafting, followed by a tension-band configuration. The mean follow-up was five years (range 3 to 6 years). RESULTS: Union occurred in all the patients. None of the patients had shoulder pain at rest or during activities. When compared with the normal side, the range of motion and the strength of the shoulder were normal in all the patients, with Constant scores being 89, 96, and 98, respectively. CONCLUSION: Identification of the type of os acromiale is important for the treatment plan. The meso-acromion is particularly important because of its greater size and its role in narrowing the subacromial space. It is necessary to determine whether the meso-acromion fragment is mobile. Dynamic arthroscopic examination offers significant help in this respect.

Acromion↗
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↗
PubMed2005

Acromion-fixation of glenoid components in total shoulder arthroplasty.

Successful design of components for total shoulder arthroplasty has proven to be challenging. This is because of the difficulties in maintaining fixation of the component that inserts into the scapula; i.e., the glenoid component. Glenoid components that are fixated to both the glenoid and acromion (a long process extending medially on the dorsal aspect of the scapula) have the possible advantage of greater stability over those that are fixated to the glenoid alone. In this study, a finite element analysis is used to investigate whether or not acromion fixation is advantageous for glenoid components. Full muscle loading and joint reaction forces are included in the finite element model. Reflective photoelasticity of five scapulae is used to obtain experimental data to compare with results from the finite element analysis, and it confirms the structural behaviour of the finite element model. When implanted with an acromion-fixated prosthesis, it is found that high unphysiological stresses occur in the scapula bone, and that stresses in the fixation are not reduced. Very high stresses are predicted in that part of the prosthesis which connects the acromion to the glenoid. It is found that the very high stresses are partly in response to the muscle and joint reaction forces acting at the acromion. It is concluded that, because of the relatively high forces acting at the acromion, fixation to it may not be the way forward in glenoid component design.

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↗
PubMed2002

The correlation between bursoscopic and histologic findings of the acromion undersurface in patients with subacromial impingement syndrome.

PURPOSE: Ideally, decompression of the coracoacromial arch in patients with shoulder impingement syndrome should be done only at the site of impingement. However, it is very difficult to determine the exact site of impingement before acromioplasty. The objectives of this study were to investigate the relationship between findings and the histopathologic changes of the undersurface of the acromion in subacromial impingement syndrome and to evaluate the usefulness of bursoscopy in identifying the site of the impingement. TYPE OF STUDY: Case series. METHODS: We investigated the correlation between subacromial bursoscopic findings and histopathologic changes of the coracoacromial arch in 50 patients with subacromial impingement syndrome. The acromion and the coracoacromial ligaments removed during acromioplasty were fixed in 10% formalin, decalcified, embedded in paraffin, and cut into sections along the direction of the coracoacromial ligament. After staining with toluidine blue, the specimens were evaluated for pathology using an optical microscope. RESULTS: The pathologic changes were classified into 3 types according to the direction of proliferative fibrocartilaginous changes at the enthesis of the acromial insertion of the coracoacromial ligament. The bursoscopic findings were classified into 4 types. Subacromial abnormalities in the bursoscopy findings correlated with histopathologic changes at the undersurface of the acromion. On the other hand, cases with normal findings on the undersurface of the acromion on bursoscopy had hypertrophic changes of fibrocartilage at the insertion of the coracoacromial ligament to the acromion. These results suggest that, with normal findings on the undersurface of the acromion in patients with subacromial impingement syndrome, there is impingement at the coracoacromial ligament. CONCLUSIONS: Bursoscopy is a useful procedure to determine the impingement site in patients with subacromial impingement.

Acromion↗
PubMed2006

"Uncoverage" of the humeral head by the anterolateral acromion and its relationship to full-thickness rotator cuff tears.

The relationship between the humeral head and the anterolateral acromion was compared for subjects with and without full-thickness rotator cuff tears, as indicated by magnetic resonance imaging, using a case-control design. "Uncoverage" of the humeral head by the anterolateral acromion was defined as the percentage of the humeral head width not covered superiorly by the anterolateral acromion, as measured digitally on magnetic resonance imaging scans of the shoulder in the oblique coronal plane. The uncoverage of the humeral head by the anterolateral acromion was 32.0% for men > or = 40 years of age with normal rotator cuffs (n = 39) and 38.2% for men > or = 40 years of age with full-thickness rotator cuff tears (n = 43). The difference in uncoverage of 6.2% was statistically significant (p < 0.001). The uncoverage of the humeral head by the anterolateral acromion was 36.1% for women > or = 40 years of age with normal rotator cuffs (n = 10) and 41.8% for women > or = 40 years of age with full-thickness rotator cuff tears (n = 17). The difference in uncoverage of 5.72% was not statistically significant with the number of subjects available (p = 0.108). We concluded that increased uncoverage of the humeral head by the anterolateral acromion may be a factor in the pathogenesis of full-thickness rotator cuff tears.

Acromion↗
PubMed2005

Histological and ultrastructural changes in the undersurface of the acromion with subacromial impingement.

BACKGROUND: We examined histological changes in the undersurface of the acromion in patients with symptoms of subacromial impingement, in order to clarify whether or not these changes are the main cause of rotator cuff tear. METHODS: We studied 39 shoulders. The undersurface of the acromion and the coracoacromial ligament were examined by light microscopy and transmission electron microscopy. RESULTS: The distinct four-layer structure seen in the undersurface of the acromion of normal subjects was not found in any of our patients. In patients with full-thickness cuff tear, the extent of the tear had a greater association with the degree of degeneration in the undersurface of the acromion than age or the duration of illness. There was little association between structural changes in the coracoacromial ligament and the extent of or the presence of full-thickness cuff tear, or the duration of illness, but there was a strong association with patient age. INTERPRETATION: The histological changes in the undersurface of the acromion in patients without cuff tear were merely minute changes compared to those in patients with full-thickness cuff tear. We conclude that the advanced degenerative changes in the undersurface of the acromion result from full-thickness cuff tear.

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↗