•
Coracoid Process Fracture Diagnosis in Acromioclavicular Separation 1
Diagnostic Radiology
Jay J. Protass, M.D., Frank V. Stampfli, M.D., and John C. Osmer, M.D. Three cases demonstrating avulsion of the coracoid process from the scapula associated with acromioclavicular separation are presented. Two patients were adolescents and one a young adult, suggesting that the coracoid base epiphyseal plate In this age group may be weaker than the coracoclavicular ligaments. A cranially-angled view of the shoulder was diagnostic in two cases. Recognition of this condition is mandatory if the orthopedist is planning fixation of the clavicle to the coracoid to remedy an acromioclavicular separation. I~DEX
TERMS:
Scapula. Shoulder
Radiology 118:61-64, July 1975
• of the coracoid process of the scapula 'is an unusual isolated finding (1, 2). Three cases are presented which demonstrate coracoid fracture in association with acromioclavicular separation. Although this has been known to occur (3), the fracture is often quite subtle and could be overlooked or misdiagnosed as an unfused epiphysis (4), unless there is a high index of suspicion. In none of the cases presented was this fracture either suspected clinically or well demonstrated on routine shoulder radiographs with axillary views. Definitive diagnosis was made either with tomography or from a cranially-angled anteroposterior view of the shoulder
F
left shoulder. The swelling and pain which were initially present subsided in two days. Physical examination a week after the accident demonstrated prominence of the acromial end of the clavicle, but no discomfort to deep palpation. The clinical impression was acromioclavicular separation. Radiographs demonstrated asymmetry between the right and left acromioclavicular joints, and minimal irregularity at the base of the left coracoid process (Fig. 3). A cranially-angled view of the left shoulder clearly demonstrated an avulsion-type fracture of the left coracoid process (Fig. 4). The patient was treated conservatively.
(5).
DISCUSSION
RACTURE
The scapular coracoid process is attached to the undersurface of the clavicle by the coracoclavicular ligaments. The rare isolated coracoid fracture is usually caused by a sharp pull of the conjoined tendon of the short head of the biceps and the coracobrachialis muscles which arise from its apex (1,2, 6). In complete acromioclavicular dislocation, the coracoclavicular ligaments usually tear, while the coracoid remains intact. The force of dislocation can occasionally avulse the coracoid process, sparing the ligaments
CASE REPORTS CASE I (P.M.): A 17-year-old boy injured his left shoulder playing football and his coach reduced something that felt "out of place". On physical examination, the patient could not elevate the arm without pain, but had no tenderness to deep palpation about the shoulder. The clinical impression was partial acromioclavicular separation. Radiographs suggested an acromioclavicular separation (Fig. 1, A) and showed the left coracoid process to be different from the uninvolved right side. Linear tomography confirmed the presence of a fracture-separation across the coracoid base (Fig. 1, B). The patient was treated conservatively. CASE II (E.S.): A 22-year-old woman injured her left shoulder in an auto accident. On physical examination, she was unable to move her arm, the shoulder was tender to palpation, and the acromial end of the clavicle was protuberant. The clinical impression was acromioclavicular separation. Radiographs with and without weight bearing confirmed the presence of a separation at the acromioclavicular junction, and suggested a coracoid base fracture (Fig. 2, A). A cranially-angled view showed the coracoid avulsion to best advantage (Fig 2, B). Open reduction with fixation of the clavicle to the acromion via two Steinmann pins was performed. The fractured coracoid was found to be in satisfactory alignment. CASE III (D.P.): A 14-year-old boy fell off his bicycle injuring his 1
(3).
Care must be taken to differentiate coracoid fracture from normally positioned unfused epiphysis (4). Obliteration of the coracoid base epiphyseal plate usually occurs between the fifteenth and eighteenth years (4, 6). The normal unfused coracoid epiphysis tends to be evenly spaced from the scapula (Fig. 5) and the two coracoid processes often appear symmetrical, but neither of these observations is absolute (4). The three cases presented showed asymmetric irregular separation at the location of the coracoid base epiphyseal plate. All patients were in the adolescent-young adult age range (14, 17, and 22 years). This suggests
From the Department of Radiology, Eden Hospital, Castro Valley, Calif. Accepted for publication in November 1974.
61
vb
62
JAY J. PROTASS, FRANK
V. STAMPFLI, AND JOHN C. OSMER
July 1975
Fig. 1. CASE I. A. Frontal view of the left shoulder demonstrates separation at the acromioclavicular junction. A peculiar lucency overlies the base of the coracoid process (arrow). B. A tomographic cut clearly shows a fracture-separation at the coracoid base.
Fig. 2. CASE II. A. Frontal, weight-bearing view of the left shoulder shows an acromioclavicular separation with a fracture through the coracoid base (arrow). B. View of the left shoulder with the central ray angled 30 0 cephalad demonstrates the fracture extending completely across the base of the coracoid process.
that in separation of the clavicle from the scapula in this age group, the coracoid epiphyseal plate may be weak-
Factors which aided in correctly diagnosing our cases were: (a) careful comparison with the opposite side, (b)
er than the coracoclavicular ligaments.
frontal tomography, and (c) an anteroposterior upward
The diagnosis of coracoid fracture may be missed because the coracoid process normally projects upward and medially, and then forward and laterally (6), appearing foreshortened in the standard frontal view.
tilt view which elongates the coracoid. Our evaluation of the coracoid process includes a 30-35° cephalad angulation of the central ray with the patient supine. This view was originally used to study the acromioclavicular
Vol. 116
CORACOID PROCESS FRACTURE DIAGNOSIS IN ACROMIOCLAVICULAR FRACTURE
63
Diagnostic Radiology
Fig. 3. CASE III. A. Frontal, weight-bearing view of the right shoulder shows a normal acromioclavicular articulation and coracoid process. B. A similar view of the lett shoulder demonstrates elevation of the lateral end of the clavicle with respect to the acromion, indicating a separation. Very minimal asymmetry between the two coracoid processes is apparent. Fig. 4. CASE III. A cranially-angled view of the lett shoulder demonstrates a fracture across the coracoid process base.
articulations (5). It is especially useful in the patient with a painful or immobilized shoulder, as no manipulation is required. The importance of recognition of coracoid fracture in acromioclavicular separation is related to treatment. One surgical method of repairing acromioclavicular separation consists of fixation of the clavicle to the coracoid with a lag screw or suture (8, 9, 10). This naturally would be contraindicated if the coracoid process were not intact. ACKNOWLEDGMENT: We wish to thank Doctors Robert Freiberger, David Korn, and Frank Mainzer for their constructive comments, and Lillian Curno for her secretarial assistance.
REFERENCES 1. Rounds RC: Isolated fracture of the coracoid process. J Bone Joint Surg [Am] 31:662-663, Jul 1949 2. Benton J, Nelson C: Avulsion of the coracoid process in an athlete. Report of a case. J Bone Joint Surg [Am] 53:356-358, Mar 1971
Fig. 5. An axillary view demonstrates a normal coracoid base epiphyseal plate (arrows). The distance between the coracoid process and the scapula at the plate level is relatively constant.
64
JAY J. PROTASS, FRANK
V. STAMPFLI, AND JOHN C. OSMER
3. Moseley HF: Shoulder Lesions. Edinburgh and London, Churchill Livingstone, 3d ed, 1969, pp 52, 139,222 4. Kohler A, Zimmer EA:. Borderlands of the Normal and Early Pathologic in Skeletal Roentgenology. New York, Grune & Stratton, 3d Am ed, 1968, pp 151, 156-158 5. Zanca P: Shoulder pain: involvement of the acromioclavIcular joint. Am J Roentgenol 112:493-506, Jul 1971 6. Gray H: Anatomy of the Human Body. Philadelphia, Lea & Febiger, 26th ed, 1954, pp 243,244 7. Keats TE: An Atlas of Normal Roentgen Varianfs that may Simulate Disease. Chicago, Year Book Medical Publishers, 1973, p 119
July 1975
8. Bosworth BM: Acromioclavicular separation: new method of repair. Surg Gynecol Obstet 73:866-871, Dec 1941 9. Kennedy JC, Cameron H: Complete dislocation of the acromioclavicular joint. J Bone Joint Surg [Br] 36:202-208, May 1954 10. Moseley HF: Athletic injuries to the shoulder region. Am J Surg 98:401-422, Sep 1959
Department of Radiology Eden Hospital' Castro Valley, Calif. 94546
Coracoid Process Fracture Diagnosis in Acromioclavicular Separation 1
Diagnostic Radiology
Jay J. Protass, M.D., Frank V. Stampfli, M.D., and John C. Osmer, M.D. Three cases demonstrating avulsion of the coracoid process from the scapula associated with acromioclavicular separation are presented. Two patients were adolescents and one a young adult, suggesting that the coracoid base epiphyseal plate In this age group may be weaker than the coracoclavicular ligaments. A cranially-angled view of the shoulder was diagnostic in two cases. Recognition of this condition is mandatory if the orthopedist is planning fixation of the clavicle to the coracoid to remedy an acromioclavicular separation. I~DEX
TERMS:
Scapula. Shoulder
Radiology 118:61-64, July 1975
• of the coracoid process of the scapula 'is an unusual isolated finding (1, 2). Three cases are presented which demonstrate coracoid fracture in association with acromioclavicular separation. Although this has been known to occur (3), the fracture is often quite subtle and could be overlooked or misdiagnosed as an unfused epiphysis (4), unless there is a high index of suspicion. In none of the cases presented was this fracture either suspected clinically or well demonstrated on routine shoulder radiographs with axillary views. Definitive diagnosis was made either with tomography or from a cranially-angled anteroposterior view of the shoulder
F
left shoulder. The swelling and pain which were initially present subsided in two days. Physical examination a week after the accident demonstrated prominence of the acromial end of the clavicle, but no discomfort to deep palpation. The clinical impression was acromioclavicular separation. Radiographs demonstrated asymmetry between the right and left acromioclavicular joints, and minimal irregularity at the base of the left coracoid process (Fig. 3). A cranially-angled view of the left shoulder clearly demonstrated an avulsion-type fracture of the left coracoid process (Fig. 4). The patient was treated conservatively.
(5).
DISCUSSION
RACTURE
The scapular coracoid process is attached to the undersurface of the clavicle by the coracoclavicular ligaments. The rare isolated coracoid fracture is usually caused by a sharp pull of the conjoined tendon of the short head of the biceps and the coracobrachialis muscles which arise from its apex (1,2, 6). In complete acromioclavicular dislocation, the coracoclavicular ligaments usually tear, while the coracoid remains intact. The force of dislocation can occasionally avulse the coracoid process, sparing the ligaments
CASE REPORTS CASE I (P.M.): A 17-year-old boy injured his left shoulder playing football and his coach reduced something that felt "out of place". On physical examination, the patient could not elevate the arm without pain, but had no tenderness to deep palpation about the shoulder. The clinical impression was partial acromioclavicular separation. Radiographs suggested an acromioclavicular separation (Fig. 1, A) and showed the left coracoid process to be different from the uninvolved right side. Linear tomography confirmed the presence of a fracture-separation across the coracoid base (Fig. 1, B). The patient was treated conservatively. CASE II (E.S.): A 22-year-old woman injured her left shoulder in an auto accident. On physical examination, she was unable to move her arm, the shoulder was tender to palpation, and the acromial end of the clavicle was protuberant. The clinical impression was acromioclavicular separation. Radiographs with and without weight bearing confirmed the presence of a separation at the acromioclavicular junction, and suggested a coracoid base fracture (Fig. 2, A). A cranially-angled view showed the coracoid avulsion to best advantage (Fig 2, B). Open reduction with fixation of the clavicle to the acromion via two Steinmann pins was performed. The fractured coracoid was found to be in satisfactory alignment. CASE III (D.P.): A 14-year-old boy fell off his bicycle injuring his 1
(3).
Care must be taken to differentiate coracoid fracture from normally positioned unfused epiphysis (4). Obliteration of the coracoid base epiphyseal plate usually occurs between the fifteenth and eighteenth years (4, 6). The normal unfused coracoid epiphysis tends to be evenly spaced from the scapula (Fig. 5) and the two coracoid processes often appear symmetrical, but neither of these observations is absolute (4). The three cases presented showed asymmetric irregular separation at the location of the coracoid base epiphyseal plate. All patients were in the adolescent-young adult age range (14, 17, and 22 years). This suggests
From the Department of Radiology, Eden Hospital, Castro Valley, Calif. Accepted for publication in November 1974.
61
vb
62
JAY J. PROTASS, FRANK
V. STAMPFLI, AND JOHN C. OSMER
July 1975
Fig. 1. CASE I. A. Frontal view of the left shoulder demonstrates separation at the acromioclavicular junction. A peculiar lucency overlies the base of the coracoid process (arrow). B. A tomographic cut clearly shows a fracture-separation at the coracoid base.
Fig. 2. CASE II. A. Frontal, weight-bearing view of the left shoulder shows an acromioclavicular separation with a fracture through the coracoid base (arrow). B. View of the left shoulder with the central ray angled 30 0 cephalad demonstrates the fracture extending completely across the base of the coracoid process.
that in separation of the clavicle from the scapula in this age group, the coracoid epiphyseal plate may be weak-
Factors which aided in correctly diagnosing our cases were: (a) careful comparison with the opposite side, (b)
er than the coracoclavicular ligaments.
frontal tomography, and (c) an anteroposterior upward
The diagnosis of coracoid fracture may be missed because the coracoid process normally projects upward and medially, and then forward and laterally (6), appearing foreshortened in the standard frontal view.
tilt view which elongates the coracoid. Our evaluation of the coracoid process includes a 30-35° cephalad angulation of the central ray with the patient supine. This view was originally used to study the acromioclavicular
Vol. 116
CORACOID PROCESS FRACTURE DIAGNOSIS IN ACROMIOCLAVICULAR FRACTURE
63
Diagnostic Radiology
Fig. 3. CASE III. A. Frontal, weight-bearing view of the right shoulder shows a normal acromioclavicular articulation and coracoid process. B. A similar view of the lett shoulder demonstrates elevation of the lateral end of the clavicle with respect to the acromion, indicating a separation. Very minimal asymmetry between the two coracoid processes is apparent. Fig. 4. CASE III. A cranially-angled view of the lett shoulder demonstrates a fracture across the coracoid process base.
articulations (5). It is especially useful in the patient with a painful or immobilized shoulder, as no manipulation is required. The importance of recognition of coracoid fracture in acromioclavicular separation is related to treatment. One surgical method of repairing acromioclavicular separation consists of fixation of the clavicle to the coracoid with a lag screw or suture (8, 9, 10). This naturally would be contraindicated if the coracoid process were not intact. ACKNOWLEDGMENT: We wish to thank Doctors Robert Freiberger, David Korn, and Frank Mainzer for their constructive comments, and Lillian Curno for her secretarial assistance.
REFERENCES 1. Rounds RC: Isolated fracture of the coracoid process. J Bone Joint Surg [Am] 31:662-663, Jul 1949 2. Benton J, Nelson C: Avulsion of the coracoid process in an athlete. Report of a case. J Bone Joint Surg [Am] 53:356-358, Mar 1971
Fig. 5. An axillary view demonstrates a normal coracoid base epiphyseal plate (arrows). The distance between the coracoid process and the scapula at the plate level is relatively constant.
64
JAY J. PROTASS, FRANK
V. STAMPFLI, AND JOHN C. OSMER
3. Moseley HF: Shoulder Lesions. Edinburgh and London, Churchill Livingstone, 3d ed, 1969, pp 52, 139,222 4. Kohler A, Zimmer EA:. Borderlands of the Normal and Early Pathologic in Skeletal Roentgenology. New York, Grune & Stratton, 3d Am ed, 1968, pp 151, 156-158 5. Zanca P: Shoulder pain: involvement of the acromioclavIcular joint. Am J Roentgenol 112:493-506, Jul 1971 6. Gray H: Anatomy of the Human Body. Philadelphia, Lea & Febiger, 26th ed, 1954, pp 243,244 7. Keats TE: An Atlas of Normal Roentgen Varianfs that may Simulate Disease. Chicago, Year Book Medical Publishers, 1973, p 119
July 1975
8. Bosworth BM: Acromioclavicular separation: new method of repair. Surg Gynecol Obstet 73:866-871, Dec 1941 9. Kennedy JC, Cameron H: Complete dislocation of the acromioclavicular joint. J Bone Joint Surg [Br] 36:202-208, May 1954 10. Moseley HF: Athletic injuries to the shoulder region. Am J Surg 98:401-422, Sep 1959
Department of Radiology Eden Hospital' Castro Valley, Calif. 94546
