Double acromion and coracoid processes.
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Humans↗
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[Isolated fractures of the acromion].
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Adolescent↗
[Conservative scapulo-cleido-humerectomy for osteosarcoma of the acromion].
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Adolescent↗
Histological analysis of the coracoacromial arch: correlation between age-related changes and rotator cuff tears.
The purpose of this study was to analyze age-related changes in the coracoacromial arch and correlate these degenerative changes with rotator cuff tears. We obtained 80 shoulders from 40 cadavers. The mean age at death was 58.4 years. We performed a gross examination of the rotator cuff and the acromion and histological examination of the coracoacromial ligament. The statistical significance of any difference for each group considered was determined by Student's t-test. The rotator cuff was normal in 66 specimens; there was an articular-side partial tear in 4 cases, a bursal-side partial tear in 6 cases, and a full-thickness tear in 4 cases. Age was correlated with increasing incidence and severity of cuff tears. We noted age-related degenerative changes in the coracoacromial ligament, degeneration of the acromial bone-ligament junction, and acromial spur formation. Anterior acromial spur was not related to the morphology of the acromion. We observed an increased incidence of bursal-side and complete cuff tears when the acromion was curved or beaked. Degenerative changes in the undersurface of the acromion were also present when the rotator cuff was normal. Bursal-side and complete cuff tears were associated with severe degenerative changes in the acromion in 100% of cases. Articular-side cuff tears were not related either to acromial morphology or degenerative changes in the coracoacromial arch. The association between cuff tears and acromial spur was more evident in the presence of a type III acromion. Our results would suggest that the incidence and severity of rotator cuff tears are correlated with aging and with the morphology of the acromion. Rotator cuff tears that involve the bursal side are often associated with changes in the coracoacromial ligament and the undersurface of the acromion. However, degenerative changes in the coracoacromial arch are always related to aging, also in the presence of a normal rotator cuff. Articular-side partial tears do not cause damage to the undersurface of the acromion.
Acromioclavicular Joint↗
Changes in acromial morphology with age.
It has not been determined whether acromial morphology is an innate anatomic characteristic or whether it represents a degenerative process with type I acromions changing to type III acromions over time. The purpose of this study was to determine the incidence of the three types of acromial morphology with respect to age. The acromial morphology of 272 patients (176 patients with no signs of mechanical impingement or rotator cuff disease and 96 patients with mechanical impingement) was determined by supraspinatus outlet radiographs. In the entire group of 272 patients there was a significant increase in the incidence of type III acromions and a decrease in the incidence of type I acromions in patients older than 50 years of age (p = 0.046). In 176 patients with no symptoms there was a very significant increase in the number of type III acromions in those patients older than 50 years of age (p = 0.004) with a corresponding decrease in the incidence of type I acromions. The incidence of the three acromial types also varied between patients with and without symptoms of mechanical impingement. The incidence of the three acromial types varies with respect to the age of the patient and whether he or she has symptoms of mechanical impingement. This raises the possibility that type I acromions may progress to type II acromions and then further change into type III acromions over time.
Acromion↗
Critical analysis of the supraspinatus outlet view: rationale for a standard scapular Y-view.
The supraspinatus outlet view has been standardized under fluoroscopic control to become reproducible and comparable; it is the normalized scapular Y-view. Four hundred four healthy shoulders from patients 20 to 80 years old and 63 shoulders with rotator cuff tears underwent x-ray evaluation and were compared. A qualitative study was carried out on the shape of the acromion in relation to Bigliani's types (I, II, III and on the presence or absence of a bony spur on the anterior part of the acromion. Quantitative measurements were determined; the subacromial peak and the spinoacromial angle were assessed for a statistical comparison among the various populations. The acromions of healthy shoulders varied with age (8% type III in patients younger than 60 years, 27% in those older than 60 years), although not significantly. The dominant side and sex of the subjects had no effect. With 29% type III acromions the shoulders with cuff tears differed from those of the healthy shoulders (14% type III). No close correlation was seen between type III acromions and cuff ruptures. The quantitative values of the acromions had no predictive value for cuff rupture. Acromion typology failed to confirm that a type III acromion was responsible for rotator cuff rupture. Spurs are found in increasing incidence with age and in the presence of cuff rupture; whether they are caused by subacromial impingement or by natural aging of the acromion is uncertain.
Acromion↗
Release and reattachment of the coracoacromial ligament: a cadaveric study.
The purpose of this study was to examine the anatomy and ability to reattach the coracoacromial ligament (CAL) after acromioplasty. Twenty-eight fresh cadaveric shoulder specimens were dissected, and the CAL dimensions and pattern of attachment were examined. The ability to reattach the CAL to the anterior acromion after acromioplasty was investigated, comparing release along the anterior acromion (traditional anterior acromioplasty) versus subperiosteal elevation from the acromial undersurface. The influence of CAL length, acromial "type," and amount of acromioplasty on reattachment were examined. In 96% of the specimens (27 of 28) confluent medial and lateral bands of the CAL insertion along the acromion precluded "selective" release. The ability to anatomically reattach the CAL was directly related to the method of ligament release (anterior release versus subperiosteal elevation) (p < 0.0001). When directly released from along the anterior acromion, the CAL could not be anatomically reattached in any specimen. Nonanatomic reattachment to a more medial anterior acromial insertion site, however, was possible in 22 (79%) of 28 specimens. Reattachment required an average medial positioning of 60% (range 16% to 88%) along the anterior acromion from the anterolateral tip. Six (21%) specimens could not be reattached despite attempted medial positioning. In contrast, when subperiosteally elevated from the anterior inferior acromion, the CAL was reattachable in all specimens, anatomically in 26 (93%) of 28. The two nonanatomic reattachments required medially reattaching the ligament's normal acromial insertion by an average of 30%. There was no relationship between specimen sex, age, presence of rotator cuff tear, type of acromion, and CAL reattachment. The confluent anatomy of the CAL does not permit "selective" release of discretely identifiable portions of the CAL (i.e., the lateral band). In cases in which CAL restoration is important, careful subperiosteal elevation from the acromial undersurface will facilitate anatomic reattachment. Standard release of the CAL from the anterior acromion precludes anatomic, and in some cases any, reattachment of the CAL.
Acromion↗
Acromial morphotype in the young asymptomatic athletic shoulder.
Several studies have documented an association between the type III acromion and rotator cuff tears. However, controversy exists as to whether the shape of the acromion is an innate anatomic characteristic. The purpose of this study was to evaluate the prevalence of the type III acromion in young asymptomatic athletes. Bilateral supraspinatus outlet radiographs were obtained in 100 Division 1 collegiate athletes (average age, 19.9 years). Only 4 (2%) of 200 shoulders were found to have a type III acromion by use of the standard subjective Bigliani classification. Eight (4%) acromion were found to be type III by the use of previously published objective criteria for acromial measurement. Our results show the type III acromion to be relatively rare in asymptomatic, young athletes, but the incidence of type III acromion in a general population of both young and older individuals is still not completely understood. However, our results accentuate the possibility that the higher incidence of type III acromion seen in older populations may in fact be related to secondary acromial changes.
Acromion↗
Relationship between os acromiale and acromioclavicular joint anatomic position.
Most of the orthopaedic literature on os acromiale is focused on the clinical implications, such as impingement and rotator cuff tears; although os acromiale is present in 8% of subjects, scarce information is reported on the causes that may predispose patients to it. Our aim is to investigate whether the origin of os acromiale is related to the position of the acromioclavicular (AC) joint. The acromions of 211 volunteers (control group) and 33 subjects without or with os acromiale were radiographically (axillary view) classified by the Edelson and Taitz method. The method distinguishes the acromion into three types on the basis of the distance between the anterior aspect of the acromion and the AC joint. Of 33 subjects with os acromiale, 11 were without pain. We have compared the frequency of the three types of acromion observed in the two investigated cohorts. Half of the acromions of the control group (52.1%) had the articular facet of the AC joint on the acromion tip, whereas in 45.4% the facet tip was located distally. On the other hand, of 33 subjects with os acromiale, 18.1% and 81.1%, respectively, had the AC joint lying on or distal to the acromion tip. Our data suggest that the greater the distance of the AC joint from the anterior edge of the acromion, the higher the likelihood of an os acromiale.
Acromioclavicular Joint↗
The coracoacromial ligament: morphology and study of acromial enthesopathy.
The coracoacromial ligament (CAL), normally a superior restraint against humeral translation, is frequently involved in rotator cuff impingement pathology. However, surgical excision of the CAL is not always clinically successful. Little anatomic information exists about the morphology and function of this ligament. The CAL and glenohumeral joint in 56 cadaveric shoulders were examined in 31 cadavers. Nineteen dimensional parameters were obtained by direct measurement. In 16 shoulders, specific attention was directed at the anterior band of the CAL. Variation exists in the morphology of the CAL. The most common configuration of the CAL was two distinct ligamentous bands that could be classified anatomically as an anterolateral band (ALB) and posteromedial band (PMB). The ALB commonly extended to the posterolateral aspect of the acromion. Furthermore, it frequently extended anterolaterally to the acromion, ending in a coracoacromial falx. Spur formation had occurred in 10 of 16 shoulders evaluated and always appeared in the ALB. Spur formation in the ALB correlated with a focal CAL that was narrower, less divergent, shorter, and thicker than a diffuse CAL that did not have a spur. The mean angle of diversion between the ALB and PMB, when a spur was present, was 31 degrees compared with 45 degrees when no spur was present. CAL band thickness varied, with the ALB being thicker at the acromion than at the coracoid and the PMB being thicker at the coracoid than at the acromion. During arthroscopic subacromial decompression, failure to visualize the anterolateral corner of the acromion adequately may result in incomplete resection of the CAL, especially if the PMB is mistaken to be the entire ligament. Incomplete removal of the CAL may be a factor in clinical failures of arthroscopic subacromial decompression. The preferential location of spurs in the ALB suggests that it is a major load-bearing structure. Furthermore, the ALB is thicker at the acromion, suggesting increased strain. Our data suggest that a possible function of the CAL is to dampen stress on the acromion from muscle activity.
Acromion↗
Acromial morphology: relation to sex, age, symmetry, and subacromial enthesophytes.
PURPOSE: To evaluate acromial shape in relation to age, sex, symmetry, and presence of subacromial enthesophytes. MATERIALS AND METHODS: Three hundred ninety-four cadaveric scapulas were reviewed. Specimens were categorized by sex and age (age range, 20-89 years). Acromial morphology was typed according to the Bigliani classification: type I, flat; type II, curved; and type III, hooked. The presence and degree of subacromial enthesopathy was recorded. Selective radiographic correlation was obtained. RESULTS: The relative percentages of acromial types I, II, and III were 22.8% (90 acromions), 68.5% (270 acromions), and 8.6% (34 acromions), respectively. There was a greater percentage of type III in men (10.2% [21 of 205] vs 6.9% [13 of 189] and type I in women (27.5% [52 of 189] vs 18.5% [38 of 205]). There was no relationship between acromial type and age (P = .667). Enthesophytes were most common in type III (20 [59%] of 34 acromions) versus type II (115 [42.6%] of 270 acromions) and type I (22 [24%] of 90 acromions). Acromial morphology was symmetric in 135 (70.7%) of 191 pairs of acromions and asymmetric in 56 pairs (29.3%). CONCLUSION: Acromial shape does not vary significantly with age. It does, however, differ between sexes. The relative percentages of the types differ from previously reported values. Acromial shape tends to be symmetric. A trend between acromial type and the presence of enthesophytes is observed.
Acromion↗
The treatment of symptomatic os acromiale.
During a four-year period, fourteen individuals (fifteen shoulders) who had been seen at the shoulder service of our institution because of pain in the shoulder had a radiographic finding of an os acromiale. On clinical examination, the pain appeared to be due to an unstable os acromiale because the patients had point tenderness over the acromion and pain on forward elevation of the shoulder. The diagnosis of an os acromiale was confirmed on radiographs, magnetic resonance images, or a bone scan. Eight patients had an associated tear of the rotator cuff. The os acromiale was located in the pre-acromion in one shoulder, the meso-acromion in eleven shoulders, and the meta-acromion in three shoulders. At the operation, the anterior aspect of the acromion was found to be unstable in all shoulders. Eleven patients (twelve shoulders) had open reduction of the os acromiale and insertion of an autogenous iliac-crest bone graft. Of those patients, four (five shoulders) had open reduction and internal fixation with a tension-band procedure with use of pins and wires. Only one of those shoulders had a solid osseous union, and the other four shoulders had a non-union that was due to a disruption of the fixation. The remaining seven patients (seven shoulders) had open reduction and internal fixation with use of cannulated screws and a tension-band construct; a solid osseous union was achieved in all but one of them. One patient had excision of the pre-acromion, which relieved the pain. Two patients who had had failed open reduction and internal fixation had excision of a grossly unstable os acromiale in the meso-acromion; both patients had pain and weakness after this procedure. Of the twelve shoulders that had open reduction and bone-grafting, seven had union of the os acromiale; the average time to radiographic and clinical union was nine weeks (range, seven to twenty weeks). We concluded that, although it is rare, symptomatic unstable os acromiale does occur and can be effectively treated with use of autogenous bone-grafting and internal fixation with a rigid tension-band construct and cannulated screws.
Acromion↗
Position of the humeral head and rotator cuff tear: an anatomical observation in cadavers.
BACKGROUND: The relationship between the humeral head position and rotator cuff tears is not well described. MATERIAL AND METHODS: We performed an anatomical study of 22 cadaveric shoulders to find out the relationship between the normal anatomical position of the humeral head and tears of the rotator cuff. After dissection, the rotator cuff pathology was documented. The position of the humeral head was noted in relation to the acromion. The humeral head with intact acromion and articulated shoulder joint was photographed from the superior aspect of the joint and the area of the humeral head outside the acromion was measured, i.e. the part of the humeral head lateral to the lateral border of the acromion process. The relationship between rotator cuff pathology and uncovering of the humeral head was determined. RESULTS: 9 specimens had a partial cuff tear, while 4 had a complete tear. Those specimens with a rotator cuff tear had a mean area of 83% of the humeral head under the acromion. The specimens that did not show a rotator cuff tear had a mean area of 61% of the humeral head under the acromion. INTERPRETATION: We suggest that there is individual variation in anatomical position of the humeral head in relation to the acromion and that this position correlates with the occurrence of rotator cuff pathology.
Cadaver↗
[Etiology of sub-acromial impingement syndrome--a biomechanical study].
Eight fresh shoulder specimen were dissected and the functional relationship of the rotator cuff tendons to the acromion was demonstrated through various arcs of shoulder motion. The scapula was fixed and the arm was elevated, rotated, and abducted by pulling the muscle tendon according to EMG activities. Using FUJI compression films the subacromial compression of the rotator cuff was measured. Different forms of acromion were tested. While moving the shoulder with normal relationship of deltoid to rotator cuff, there is no -or at least less than 0.1 mPa compression of the rotator cuff in the subacromial space. Weakness of the rotator cuff results in a moderate compression of 0.6 mPa. In type III acromion there was significant increase up to 1.0 mPa between the acromion and the rotator cuff. This study suggests, that a mechanical subacromial compression only occurs in shoulder joints with a Bigliani acromion type III and/or in joints with a imbalance of the deltoid/rotator cuff relation. Thus an acromioplasty should be primarily undertaken only if the pathology affects the acromion. If there is a muscle imbalance, we recommend a special rehabilitation program in order to strengthen the cuff-muscles the first place.
Acromion↗
The coracoacromial arch: MR evaluation and correlation with rotator cuff pathology.
The relative prevalence of various acromial shapes, appearance of the coracoacromial ligament and enthesophytes along the inferior aspect of the acromioclavicular joint in patients with and without rotator cuff tears were evaluated. Of 76 patients with clinical instability and impingement, 31 had a normal rotator cuff and 45 demonstrated a partial or full tear of the supraspinatus tendon at surgery. Results were compared with those from magnetic resonance (MR) scans of 57 asymptomatic volunteers. Of the 45 patients with a supraspinatus tear, 38% (17) had a flat acromial undersurface (type I), 40% (18) had a concave acromial undersurface (type II), 18% (8) had an anteriorly hooked acromion (type III), and 4% (2) had an inferiorly convex acromion (type IV). Among the 31 patients with a normal rotator cuff at surgery and the 57 asymptomatic volunteers, the respective prevalences of the type I acromion were 39% (12) and 44% (25), of type II 48% (15) and 35% (20), type III 3% (1) and 12% (7), and type IV 10% (3) and 9% (5). Shoulders with surgically proven rotator cuff tears showed a tendential association with a type III acromion (8/45) and statistically significant associations with a thickened coracoacromial ligament (17/45) and acromioclavicular enthesophytes (18/45). For the association between inferiorly directed acromioclavicular joint enthesophytes and rotator cuff tears, age appears to be a confounding factor. The type IV acromion, newly classified by this study, does not have a recognizable association with rotator cuff tears.(ABSTRACT TRUNCATED AT 250 WORDS)
Acromioclavicular Joint↗
A technique for arthroscopic subacromial decompression.
The control of bleeding and the determination of the appropriate amount of bone to resect are two common technical difficulties in performing arthroscopic subacromial decompression. We describe a technique that simplifies the procedure while providing more precise bone resection and contouring. First, the coracoacromial ligament is released by sectioning the anterior margin of the acromion. Bleeding is minimized with this technique because the coracoacromial ligament itself is not being cut, but rather its bony attachment is resected. An acromioplasty is then performed with the arthroscope in the lateral portal and the burr in the posterior portal. The shank of the cutter is rested against the posterior lip of the acromion, which acts as a fulcrum. The tip of the burr is placed at the deepest point of the concavity of the acromion. Bone is resected by sweeping the cutter from lateral to medial and progressing anteriorly while maintaining the angle of the burr, using the angle of the posterior acromion as a guide. In this way the appropriate amount of bone is automatically resected, resulting in a flat acromion which is tapered anteriorly and has a smooth transition to normal bone posteriorly.
Acromioclavicular Joint↗
Anterior acromial anatomy: Relevance to arthroscopic acromioplasty.
PURPOSE: To evaluate the effect of arthroscopic acromioplasty on the anterior deltoid origin. TYPE OF STUDY: In vitro cadaveric histologic study. METHODS: We performed a histologic evaluation of the anterior aspect of 15 acromions, the parameters of the anatomy of the anterior acromion, including the deltoid origin, and the morphology of the acromion. A simulated arthroscopic acromioplasty was performed and the effect on the anterior deltoid origin was determined. RESULTS: Resection of 4 mm of bone from the underside of the acromion resulted in release of 56% (+/- 11%), and resection of 5.5 mm of bone resulted in 77% (+/-15%) release of the deltoid origin. The amount of deltoid released correlated statistically with both the thickness of the acromion and the acromial angle ( P < .0001 and P = .04). CONCLUSIONS: These findings show that arthroscopic acromioplasty can cause substantial injury to the deltoid origin, that this effect is related to acromial anatomy, and that preoperative planning may help to reduce the risk of excessive deltoid origin release. CLINICAL RELEVANCE: Consideration of acromial anatomy is required to avoid deltoid detachment when performing arthroscopic acromioplasty.
Acromion↗
Acromial structure and tears of the rotator cuff.
Rotator cuff lesions have been related to the structure of the acromion. We report a clinical review of 56 shoulders and the analysis of their acromial structure as seen on the radiographic arch (outlet) view and magnetic resonance imaging. The shoulders were classified as acromial type I (flat), type II (curved), or type III (hooked). On plain radiographs 89% of type III acromions had tearing of the rotator cuff (p < 0.001). The association between acromial type as determined on magnetic resonance imaging and the presence of rotator cuff tearing was less significant. Magnetic resonance imaging offered no additional benefit over plain radiographs for determining acromial type. In addition, a method of quantitating acromial structure (the "acromial angle") was devised. This angle showed a significant association with acromial types (p < 0.0001) seen on plain radiographs and had good interobserver reproducibility (coefficient of variation, 0.1). With this measurement system a type I acromion had an acromial angle of 0 degrees to 12 degrees; a type II acromion, 13 degrees to 27 degrees; and a type III acromion, greater than 27 degrees.
Acromion↗