JBJS | Os Acromiale: Frequency, Anatomy, and Clinical Implications*

The Journal of Bone & Joint Surgery, Volume 82, Issue 3

Articles | March 01, 2000

Os Acromiale: Frequency, Anatomy, and Clinical Implications*

VINCENT JAMES SAMMARCO, M.D.†, CINCINNATI, OHIO

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Investigation performed at the Cleveland Clinic Foundation, Cleveland

The Journal of Bone & Joint Surgery. 2000; 82:394-400

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Abstract

Background: Os acromiale is present when the anterior portion of the acromion has one or more separate ossicles. Its frequency has been documented, in radiographic and anatomical studies, to be between 1 and 15 percent. Reports of os acromiale associated with subacromial pathology have been cited to imply that this entity is a cause of subacromial impingement; however, no study has demonstrated an increased frequency of os acromiale in patients with shoulder pain compared with the frequency in the general population. Inconsistencies in the literature concerning anatomy, development, and frequency prompted the current anatomical study. The purpose of this study was to better define the frequency and anatomy of os acromiale in the general population.

Methods: Two thousand three hundred and sixty-seven scapular bones from 1198 human skeletons from the Hamann-Todd Osteological Collection were studied for evidence of os acromiale. The sample consisted of specimens from 1033 men and 165 women, 843 of whom had been white and 355, black. The mean age of the individuals at the time of death was 44.7 years (range, eighteen to eighty-nine years). The frequency of os acromiale was noted, and the specimens were measured.

Results: There were 128 cases of os acromiale in ninety-six (8.0 percent) of the 1198 skeletons, and the condition was bilateral in thirty-two (33.3 percent) of the ninety-six skeletons. In twenty cases, the free fragment had been lost but it was assumed that a fragment had been present because the acromion was truncated. Os acromiale was more frequent in blacks than in whites (13.2 compared with 5.8 percent; p < 0.001) and in men than in women (8.5 compared with 4.9 percent; p = 0.09). The mean proportional length of the free fragment was 0.42 compared with the overall length of the acromion.

Care was taken to differentiate os acromiale from a normal immature acromion. Six skeletons demonstrated persistent acromial apophyses. All six cases were bilateral; seven fragments were fusing, and five were free. The oldest age at which a persistent normal apophysis was found was twenty-one years. The frequency of os acromiale in specimens from individuals who had been less than twenty-two years old was not significantly different from that in the remainder of the collection (p = 0.74). Twenty-one scapulae had a distinct circumferential line that was suggestive of an acromial joint, but the distal and proximal portions were solidly fused. However, the findings on plain axillary radiographs of sixteen of these specimens were indistinguishable from those of specimens with os acromiale.

Conclusions: An anatomical study, performed to better define the frequency and anatomy of os acromiale in the general population, showed that fused os acromiale, which has not been described previously, might be mistaken for a free ossicle in the clinical setting.

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Introduction

Introduction | Materials and Methods | Results | Discussion | References

Os acromiale is an unfused epiphysis of the anterior part of the acromion that is thought to be a potential source of shoulder pathology^{1-3,5,6,8,10,11,20,21,23}. Neumann¹⁸ credited Gruber with having first defined os acromiale as an anatomical entity in 1859. Gruber⁹ recorded three instances of os acromiale with a distinct synovial joint in 100 cadavera. Other authors have expanded this definition to include a fibrocartilaginous union^4,11,13. Reports of os acromiale as a potential source of impingement, either as a mobile fragment or from osteophytic lipping of the joint between the free fragment and the scapula, are abundant. However, to my knowledge, no study has demonstrated the frequency of os acromiale to be higher in patients with shoulder pain than in the general population. In addition, trauma to the acromial joint or synchondrosis may result in a painful condition, which may become chronic if it is not recognized and treated.

The frequency of os acromiale has ranged from 1 to 15 percent in anatomical^4,9,13,19 and radiographic^8,11,12 studies, and bilateral involvement has been reported in 41 to 62 percent of cases (Table I). Radiographic studies may contain selection bias because radiographs of symptomatic shoulders are made more often in a clinical situation. Additional error probably is introduced because the sensitivity of normal radiographs in the detection of os acromiale is low^5,8,20,23.

The purpose of the current study was to determine the frequency of os acromiale in the Hamann-Todd Osteological Collection at the Cleveland Museum of Natural History. The human specimens in this collection are the skeletons of Cleveland's unclaimed dead from 1912 to 1938. Examination of this collection eliminated sampling bias as there was no selection for symptomatic shoulders and direct observation and measurement of the acromial fragments was possible. The study was performed to define the frequency of this variant in the general population more clearly, so that its relationship to pathological conditions could be determined more accurately.

*No benefits in any form have been received or will be received from a commercial party related directly or indirectly to the subject of this article. No funds were received in support of this study.

†The Center for Orthopaedic Care, 2123 Auburn Avenue, Suite 235, Cincinnati, Ohio 45219-2906. Please address requests for reprints to V. J. Sammarco.

*No benefits in any form have been received or will be received from a commercial party related directly or indirectly to the subject of this article. No funds were received in support of this study.

†The Center for Orthopaedic Care, 2123 Auburn Avenue, Suite 235, Cincinnati, Ohio 45219-2906. Please address requests for reprints to V. J. Sammarco.

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FIG1:: Fig. 1 Photograph showing a normal, unfused apophyseal growth plate from an individual who was seventeen years old at the time of death. Note the osseous spicules and interdigitation of the fragment with the more proximal part of the acromion.

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FIG2:: Fig. 2 Photograph showing typical os acromiale with free, separate fragments and a well defined articulation.

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FIG3:: Fig. 3 Schematic drawing showing the axes of measurements obtained from specimens with os acromiale.

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FIG4-A:: Figs. 4-A and 4-B: A specimen that had a fused os acromiale. Fig. 4-A: Photograph of the specimen. A solid fusion of the distal fragment to the proximal aspect of the acromion was found on physical examination.

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FIG4-B:: Fig. 4-B Axillary radiograph demonstrating findings indistinguishable from those of an unfused os acromiale.

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FIG5:: Fig. 5 Schematic drawings showing the ossification centers of the normal acromial apophysis as described by Macalister¹³. Multiple ossification centers consolidate to form three centers along the lateral border of the acromion by the age of eighteen years and then proceed medially. (Redrawn from: Macalister, A.: Notes on the acromion. J. Anat. and Physiol., 27: plate XV, 1893.)

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TABLE I: ANATOMICAL AND RADIOGRAPHIC STUDIES OF OS ACROMIALE

*Radiographic studies included injured or symptomatic individuals only.

Study	Type of Study*	No. of Cases	Method	Frequency of Os Acromiale (percent)	Frequency of Bilaterality (percent)
Gruber⁹, 1863	Anatomical	100	Dissection of cadavera	3	Not reported
Macalister¹³, 1893	Anatomical	100	Examination of museum specimens	15	Not reported
Edelson et al.⁴, 1993	Anatomical	270	Examination of 190 specimens from 3 separate archaeologial sites and dissection of 80 cadaveric specimens	8.2	Not reported
Nicholson et al.¹⁹, 1996	Anatomical	420	Examination of museum specimens	8	41
Liberson¹², 1937	Radiographic	1800	Anteroposterior and oblique radiographs	1.3	Not reported
Liberson¹¹, 1937	Radiographic	1000	Anteroposterior radiographs; axial radiographs for questionable cases only	2.7	62
Grasso⁸, 1992	Radiographic	398	Anteroposterior and axial radiographs and computerized tomography	9.5	Not reported

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TABLE I: ANATOMICAL AND RADIOGRAPHIC STUDIES OF OS ACROMIALE

*Radiographic studies included injured or symptomatic individuals only.

Study	Type of Study*	No. of Cases	Method	Frequency of Os Acromiale (percent)	Frequency of Bilaterality (percent)
Gruber⁹, 1863	Anatomical	100	Dissection of cadavera	3	Not reported
Macalister¹³, 1893	Anatomical	100	Examination of museum specimens	15	Not reported
Edelson et al.⁴, 1993	Anatomical	270	Examination of 190 specimens from 3 separate archaeologial sites and dissection of 80 cadaveric specimens	8.2	Not reported
Nicholson et al.¹⁹, 1996	Anatomical	420	Examination of museum specimens	8	41
Liberson¹², 1937	Radiographic	1800	Anteroposterior and oblique radiographs	1.3	Not reported
Liberson¹¹, 1937	Radiographic	1000	Anteroposterior radiographs; axial radiographs for questionable cases only	2.7	62
Grasso⁸, 1992	Radiographic	398	Anteroposterior and axial radiographs and computerized tomography	9.5	Not reported

Materials and Methods

Introduction | Materials and Methods | Results | Discussion | References

Two thousand three hundred and sixty-seven scapular bones from 1198 human skeletons from the Hamann-Todd Osteological collection, which comprises human skeletons from the early twentieth century, were examined. The sample consisted of specimens from 1033 men and 165 women, 843 of whom had been white and 355 of whom had been black. At the time of death, the age of the 1198 individuals was a mean (and standard deviation) of 44.7 ± 15.2 years (range, eighteen to eighty-nine years). The mean age of the men was 45.0 ± 15.0 years, and that of the women was 42.0 ± 16.3 years; the mean age of the whites was 47.8 ± 14.6 years, and that of the blacks was 37.2 ± 14.0 years. Twenty-nine skeletons were incomplete, either because one scapula was missing or because the acromial portion of one scapula had been destroyed. Os acromiale was defined as the presence of a free fragment that articulated with a truncated acromion. In twenty specimens, this fragment had been lost and its presence was assumed on the basis of the truncated appearance of the acromion.

Care was taken to distinguish between a normal acromial apophysis and os acromiale. An unfused or fusing apophysis was easily differentiated from a true os acromiale on the basis of its morphological characteristics^4,13. A persistent normal apophysis has a rough, crescent-shaped proximal border with multiple osseous spicules that interdigitate perfectly with the proximal aspect of the acromion (Fig. 1). In contrast, os acromiale was defined as the presence of a clean, linear joint horizontal to the axis of the acromion (Fig. 2).

In specimens with an os acromiale fragment, the length of the fragment and that of the entire acromion were measured from anterior to posterior with digital calipers. The width from medial to lateral and the thickness of the os acromiale were measured at the base of the fragment, with exclusion of any osteophytes from the measurements (Fig. 3). Varying degrees of degeneration of the os acromiale articulation were detected, and some specimens showed evidence of osteophytic impingement within the subacromial space; however, no attempt was made to quantify or qualify this degeneration.

Twenty-one scapulae were noted to have a linear groove around the acromion, giving the appearance of a fused os acromiale. Radiographs were made through these scapulae in the axillary plane to determine the osseous architecture.

A likelihood-ratio chi-square test was performed on the data set to determine if there was a relationship between gender and race and the frequency of os acromiale or its bilaterality.

Results

Introduction | Materials and Methods | Results | Discussion | References

One hundred and twenty-eight cases of os acromiale were observed in ninety-six skeletons, giving an overall frequency of 8.0 percent (ninety-six of 1198). The os acromiale was bilateral in thirty-two (33.3 percent) of the ninety-six skeletons. One hundred and eight of the acromial fragments were present in the collection. The remaining twenty had been lost, but their presence was assumed on the basis of the truncated appearance of the acromion.

The mean length of the acromial fragment was 21.9 millimeters (range, 14.6 to 33.2 millimeters), and the mean proportional length was 0.42 (range, 0.29 to 0.62) compared with the entire length of the acromion. The mean width of the free acromial fragment was 28.4 millimeters (range, 17.4 to 35.2 millimeters), and the mean thickness was 9.9 millimeters (range, 6.2 to 16.6 millimeters). One unusual case was noted, with two small acromial fragments occurring medially and laterally in both scapulae.

The frequency of os acromiale was 8.5 percent in men and 4.9 percent in women (p = 0.09). The condition was bilateral in 35.2 percent of men and in 12.5 percent of women (p = 0.26). A significantly higher frequency of os acromiale was found in blacks (13.2 percent) than in whites (5.8 percent) (p < 0.001); the condition was bilateral in a significantly higher percentage of blacks (44.7 percent) than whites (22.4 percent) (p < 0.001).

Twenty-one acromions had a distinct circumferential line that was suggestive of os acromiale, but the distal and proximal portions were solidly fused. Axillary radiographs demonstrated a distinct radiolucency at this line with sclerotic margins identical to those of os acromiale in sixteen of these shoulders (Figs. 4-A and 4-B). The remaining five specimens demonstrated a solid fusion with trabecular bridging between the distal and proximal portions but with increased radiodensity at the apophyseal line.

Most of the acromial apophyses were solidly fused without visual evidence of an apophyseal remnant in specimens from individuals who had been eighteen years old (the youngest who were studied) at the time of death. Six skeletons, of individuals who had been between the ages of eighteen and twenty-one years old, had persistent apophyses. No skeleton of an individual who had been older than twenty-one years at the time of death had a persistent apophysis. All six cases were bilateral; five fragments were free, and seven were fusing. The morphology of all persistent apophyses was consistent with the ossification centers described by Macalister¹³.

Specimens with an acromial apophysis were not considered to have os acromiale. Os acromiale was present in three (9.7 percent) of the thirty-one skeletons of individuals who had been between eighteen and twenty-one years old. There was no significant difference between the frequency in this age-group and that in the skeletons of individuals who had been more than twenty-one years old (ninety-three [8.0 percent] of 1167) (p = 0.74).

Discussion

Introduction | Materials and Methods | Results | Discussion | References

Interest in os acromiale developed at the end of the nineteenth century, when French, German, and American anatomists attempted to define the development of the normal acromion. In a study of museum specimens in 1893, Macalister¹³ defined the developmental anatomy of the acromion, which proceeds from many nuclei forming in the acromial apophysis of humans when they are approximately fifteen years old. By the time that the individual is seventeen years old, these nuclei have consolidated to form three separate ossification centers along the periphery: the pre-acromial center, which serves as the attachment for the coracoacromial ligament and the anterior tendinous origin of the deltoid; the mes-acromial center, which anchors the middle tendinous fibers of the deltoid; and the met-acromial center, from which the posterior deltoid fibers originate. These three centers consolidate over the next year and ossify medially toward the clavicular facet by the time that the individual is eighteen years old (Fig. 5). Although variations were found, the immature acromions in the present study fit this description well, with three ossification centers present along the lateral edge of the acromion. Macalister thought that os acromiale was the result of failure of the pre-acromial and mes-acromial centers to unite with the spine and the met-acromial center.

In a single case study, Folliasson⁷, citing a review of the literature by Neumann¹⁸, reported that the ossification centers of the acromion appeared to consolidate as three separate ossification centers from posterior to anterior. Os acromiale was hypothesized to develop when one or more of these ossification centers failed to unite with the others. The size and shape of the free acromial fragment were thought to depend on which of the ossification centers had failed to unite. This schema was popularized by Liberson¹¹ in 1937, and its use has persisted in the current orthopaedic literature^{2,5,6,8,10,14,15,19,20,22,23}. On the basis of this classification, Bigliani et al.² recommended surgical excision rather than repair of os acromiale in the treatment of subacromial impingement. Park et al.²⁰ expanded the classification, designating seven possible patterns of os acromiale, although only three were observed.

The observations in the current study are in agreement with those of Edelson et al.⁴; neither study revealed any evidence of this stacked configuration of ossification centers in the anatomical specimens that were examined. It is also interesting that the frequency of os acromiale in skeletons of individuals who had been twenty-one years old or younger was no greater than that in the remainder of the collection. This observation, combined with the fact that the anatomy of a normal fusing apophysis is markedly different from that of os acromiale, indicates that the condition is a separate morphological entity and not merely a normal apophysis that has failed to fuse. The current study is apparently the first to demonstrate the increased frequency of os acromiale and bilateral os acromiale in black and male individuals, and these findings suggest that there may be a genetic component to its development.

The presence of a so-called fused os acromiale has not been reported previously, to my knowledge. The appearance of a normal acromion on axillary radiographs was that of a single osseous entity with uninterrupted trabeculation from posterior to anterior. Some specimens in the present study had a distinct radiolucent line horizontal to the axis of the acromion that was indistinguishable from the joint of an os acromiale. Physical examination of the specimens showed only a thin line circumscribing the acromion at the level of the radiolucency but solid osseous fusion between the structures. The morphological characteristics of os acromiale appear to be present in a continuum, ranging from a mobile fragment with a distinct synovial articulation^9,13 to a fibrocartilaginous union¹³ to a nearly complete union with no mobility. If there is truly a relationship between os acromiale and subacromial pathology, it is unlikely that an acromion with a nearly complete union would act any differently clinically from a normal acromion, although a nearly fused os acromiale may be indistinguishable on radiographic analysis from an unfused os acromiale. Computerized tomography⁸ and magnetic resonance imaging^20,22 have been used for the identification of os acromiale and could potentially be used to characterize the articulation.

Several skeletons demonstrated osteophytic spurring of the acromial joint, which may act as a source of impingement as described by Edelson et al.⁴. In a report of eight cases of os acromiale associated with a rotator cuff tear, Mudge et al.¹⁵ stated that abnormal motion through the acromial joint may in itself contribute to impingement. Warner et al.²³ hypothesized that the anterior part of the deltoid may actively force the os acromiale to impinge on the rotator cuff tendons during contraction. Neer¹⁶ noted os acromiale in twenty-six patients who had rotator cuff-tear arthropathy; this is a higher frequency than would be expected on the basis of the current anatomical study and those of others^4,19.

The number of cases in Neer's study¹⁶ is small, but the findings lend some support to the idea that os acromiale may indeed predispose to subacromial pathology. There is little else in the literature to support this concept, in spite of what appears to be its broad acceptance^{2,3,5,6,8,10,11,15,19-21,23}. In a review of the pathophysiology of subacromial impingement, Neer et al.¹⁷ later wrote that there was not an increased frequency of unfused acromial epiphysis in patients who had rotator cuff disease. It is hoped that better definition of the frequency and anatomy of os acromiale in the general population will lead to a more accurate definition of its role in shoulder pathology.

References

Introduction | Materials and Methods | Results | Discussion | References

Becker, F.: Das Os acromiale und seine Differentialdiagnose. Fortschr. Geb. Rontgen.,49: 135, 1934.49135 1934

Bigliani, L. U.; Norris, T. R.; Fischer, J.; and Neer, C. S.: The relationship between unfused acromial epiphysis and subacromial impingement lesions. Orthop. Trans.,7: 138, 1983.7138 1983

Dennis, D. A.; Ferlic, D. C.; and Clayton, M. L.: Acromial stress fractures associated with cuff-tear arthropathy. A report of three cases. J. Bone and Joint Surg.,68-A: 937-940, July 1986.68-A937 1986

Edelson, J. G.; Zuckerman, J.; and Hershkovitz, I.: Os acromiale: anatomy and surgical implications. J. Bone and Joint Surg.,75-B(4): 551-555, 1993.75-B(4)551 1993

Elleuch, M. H.; Baklouti, S.; Mnif, J.; Kchaou, M. S.; and Sellami, S.: Os acromial et syndrome de la coiffe des rotateurs. A propos de 12 cas et revue de la littérature. J. Radiol.,75: 237-240, 1994.75237 1994 [PubMed]

Fery, A., and Sommelet, J.: L'os acromial: signification—diagnostic—pathologie. A propos de 28 observations dont 2 décollements-fractures. Rev. chir. orthop.,74: 160-172, 1988.74160 1988 [PubMed]

Folliasson, A.: Un cas d'os acromial. Rev. orthop.,20: 533-538, 1933.20533 1933

Grasso, A.: Incidenza e ruolo dell'os acromiale syndrome da attrito acromio-omerale. Radiol. Med.,84: 567-570, 1992.84567 1992 [PubMed]

Gruber, W.: Über die Arten der Acromialknochen und accidentellen Acromialgelenke. Arch. Anat., Physiol. und wissensch. Med., 373-387, 1863.

Hutchinson, M. R., and Veenstra, M. A.: Arthroscopic decompression of shoulder impingement secondary to os acromiale. Arthroscopy,9: 28-32, 1993.928 1993 [PubMed]

Liberson, F.: Os acromiale—a contested anomaly. J. Bone and Joint Surg.,19: 683-689, July 1937.19683 1937

Liberson, F.: The value and limitation of the oblique view as compared with the ordinary anteroposterior exposure of the shoulder. A report of the use of the oblique view in 1,800 cases. Am. J. Roentgenol.,37: 498-509, 1937.37498 1937

Macalister, A.: Notes on the acromion. J. Anat. and Physiol.,27: 245-251, 1893.27245 1893

McClure, J. G., and Raney, R. B.: Anomalies of the scapula. Clin. Orthop.,110: 22-31, 1975.11022 1975 [PubMed]

Mudge, M. K.; Wood, V. E.; and Frykman, G. K.: Rotator cuff tears associated with os acromiale. J. Bone and Joint Surg.,66-A: 427-429, March 1984.66-A427 1984

Neer, C. S., II: Impingement lesions. Clin. Orthop.,173: 70-77, 1983.17370 1983 [PubMed]

Neer, C. S., II; Craig, E. V.; and Fukuda, H.: Cuff-tear arthropathy. J. Bone and Joint Surg.,65-A: 1232-1244, Dec. 1983.65-A1232 1983

Neumann, W.: Über das "Os acromiale". Fortschr. Geb. Rontgen.,25: 180-191, 1918.25180 1918

Nicholson, G. P.; Goodman, D. A.; Flatow, E. L.; and Bigliani, L. U.: The acromion: morphologic condition and age-related changes. A study of 420 scapulas. J. Shoulder and Elbow Surg.,5: 1-11, 1996.51 1996

Park, J. G.; Lee, J. K.; and Phelps, C. T.: Os acromiale associated with rotator cuff impingement: MR imaging of the shoulder. Radiology,193: 255-257, 1994.193255 1994 [PubMed]

Swain, R. A.; Wilson, F. D.; and Harsha, D. M.: The os acromiale: another cause of impingement. Med. and Sci. Sports and Exerc.,28: 1459-1462, 1996.281459 1996

Uri, D. S.; Kneeland, J. B.; and Herzog, R.: Os acromiale: evaluation of markers for identification on sagittal and coronal oblique MR images. Skel. Radiol.,26: 31-34, 1997.2631 1997

Warner, J. J. P.; Beim, G. M.; and Higgins, L.: The treatment of symptomatic os acromiale. J. Bone and Joint Surg.,80-A: 1320-1326, Sept. 1998.80-A1320 1998

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FIG2:: Fig. 2 Photograph showing typical os acromiale with free, separate fragments and a well defined articulation.

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FIG3:: Fig. 3 Schematic drawing showing the axes of measurements obtained from specimens with os acromiale.

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FIG4-B:: Fig. 4-B Axillary radiograph demonstrating findings indistinguishable from those of an unfused os acromiale.

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TABLE I: ANATOMICAL AND RADIOGRAPHIC STUDIES OF OS ACROMIALE

*Radiographic studies included injured or symptomatic individuals only.

Study	Type of Study*	No. of Cases	Method	Frequency of Os Acromiale (percent)	Frequency of Bilaterality (percent)
Gruber⁹, 1863	Anatomical	100	Dissection of cadavera	3	Not reported
Macalister¹³, 1893	Anatomical	100	Examination of museum specimens	15	Not reported
Edelson et al.⁴, 1993	Anatomical	270	Examination of 190 specimens from 3 separate archaeologial sites and dissection of 80 cadaveric specimens	8.2	Not reported
Nicholson et al.¹⁹, 1996	Anatomical	420	Examination of museum specimens	8	41
Liberson¹², 1937	Radiographic	1800	Anteroposterior and oblique radiographs	1.3	Not reported
Liberson¹¹, 1937	Radiographic	1000	Anteroposterior radiographs; axial radiographs for questionable cases only	2.7	62
Grasso⁸, 1992	Radiographic	398	Anteroposterior and axial radiographs and computerized tomography	9.5	Not reported

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TABLE I: ANATOMICAL AND RADIOGRAPHIC STUDIES OF OS ACROMIALE

*Radiographic studies included injured or symptomatic individuals only.

Study	Type of Study*	No. of Cases	Method	Frequency of Os Acromiale (percent)	Frequency of Bilaterality (percent)
Gruber⁹, 1863	Anatomical	100	Dissection of cadavera	3	Not reported
Macalister¹³, 1893	Anatomical	100	Examination of museum specimens	15	Not reported
Edelson et al.⁴, 1993	Anatomical	270	Examination of 190 specimens from 3 separate archaeologial sites and dissection of 80 cadaveric specimens	8.2	Not reported
Nicholson et al.¹⁹, 1996	Anatomical	420	Examination of museum specimens	8	41
Liberson¹², 1937	Radiographic	1800	Anteroposterior and oblique radiographs	1.3	Not reported
Liberson¹¹, 1937	Radiographic	1000	Anteroposterior radiographs; axial radiographs for questionable cases only	2.7	62
Grasso⁸, 1992	Radiographic	398	Anteroposterior and axial radiographs and computerized tomography	9.5	Not reported