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The fate of the coracoacromial ligament in arthroscopic acromioplasty: An anatomical study
The fate of the coracoacromial ligament in arthroscopic acromioplasty: An anatomical study Justin L. Hunt, BMBS, Robert J. Moore, PhD, and Jeganath Krishnan, FRACS, Bedford Park and Adelaide, South Australia, Australia
This study defines the normal anatomical relationships among the coracoacromial ligament, the deltoid, and the acromion in cadavers. The effect of arthroscopic acromioplasty on the acromial attachments of the coracoacromial ligament and the anterior fibers of the deltoid was also studied. After arthroscopic acromioplasty, the fibers of coracoacromial ligament and overlying deltoid inserting into the anterior part of the acromion remained attached to the acromion by a bridge of tissue composed of periosteum and collagen fibers of the coracoacromial ligament and deltoid tendon. We have called this the coracoacromialdeltoid-periosteal complex; it has not previously been described. This study demonstrates that arthroscopic acromioplasty preserves the acromial attachment of the coracoacromial ligament and the anterior fibers of the deltoid. (J Shoulder Elbow Surg 2000;9:491-4.)
S
ubacromial impingement syndrome is a common cause of shoulder pain. The acromion, coracoacromial ligament (CAL),1,13,21 acromioclavicular (AC) joint, coracoid,7 and greater tuberosity of the humerus10 have all been implicated in subacromial impingement. Acromioplasty, division of the CAL, and shaving of the greater tuberosity10 have all been performed to treat this syndrome. The CAL has a number of functions, including superior restraint of the glenohumeral joint5,15,17 and stabilization of the acromion16 and the AC joint.23 Flatow et al5 and Moorman et al17 have reported that the rotator cuff and the long head of biceps are the primary structures preventing superior subluxation of the humeral head and that the CAL is a final restraint. They concluded that aggressive decompression in the presence of an unrepaired or recurrent tendon defect may potentially impair shoulder function. These studies emphaFrom the Department of Orthopaedics, Flinders Medical Centre, Bedford Park (Drs Hunt and Krishnan), and the Institute of Medical and Veterinary Science, Adelaide (Dr Moore); South Australia, Australia. Reprint requests: J. Krishnan, FRACS, Department of Orthopaedics, Flinders Medical Centre, Bedford Park, South Australia, Australia. Copyright © 2000 by Journal of Shoulder and Elbow Surgery Board of Trustees. 1058-2746/2000/$12.00 + 0 32/1/109319 doi:10.1067/mse.2000.109319
sized that the CAL is not a vestigial structure but rather an important stabilizing structure and should be spared when possible. The anatomy of the CAL has been studied by a number of authors.3,11,23,24 The CAL has a variable morphology3,11,22,23; it is described as Y-shaped, quadrangular, or multiply banded. In its most common form, 2 bands form a Y-shaped structure12,24; the bands, classified as posteromedial and anterolateral, converge from the coracoid origin and blend midway to the acromial attachment. The CAL has fibers that insert into the anterior and inferior surface of the acromion. These also blend with the inferior surface of the AC joint.24 The CAL and deltoid attachments to the anterior acromion are intimately related. However, the gross anatomical and histologic relationship of the CAL and deltoid attachments to the anterior acromion has not been well defined. Arthroscopic anterior acromioplasty has gained wide acceptance in treating those patients with subacromial impingement syndrome,9 the results being comparable to those obtained through use of open acromioplasty,4,9 with arguably reduced morbidity. Division of the CAL during arthroscopic acromioplasty is controversial, Ellman4 and Gartsman9 being proponents. Flatow et al5 and Moorman et al17 believe that the CAL should be preserved in the presence of an irreparable cuff tear. In open anterior acromioplasty as described by Neer18 and in the modified Neer acromioplasty as described by Rockwood and Lyons,22 the CAL and deltoid attachments to the acromion are completely detached from the acromion. The CAL is resected and the deltoid is reattached to the acromion. The effect of arthroscopic acromioplasty on the anterior fibers of deltoid has recently been reported by Kumar et al14; however, some detachment of the anterior fibers of the deltoid occurred when mock arthroscopic acromioplasties were performed, and Kumar et al concluded that this did not compromise function. This was supported by the favorable clinical results of arthroscopic acromioplasty.4,9 The present study defines the normal histologic and gross anatomical relationships among the CAL, the deltoid, and the acromion in cadavers. The effect of arthroscopic acromioplasty on the acromial attachments of the CAL and the anterior fibers of the deltoid was also studied.
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Figure 1 Sagittal section of anterior acromion (A) shows attachments of deltoid (D) and coracoacromial ligament (CAL).
METHODS In the first part of the study, we examined the normal anatomy of the CAL in 10 fresh cadaver shoulder specimens. The cadavers ranged in age from 68 to 85 years (average, 72 years). None of the specimens had rotator cuff tears or palpable anterior acromial osteophytes. The skin and subcutaneous tissue was removed from the specimen. The deltoid was divided through use of a transverse incision 3 cm below its origin from the acromion. An osteotomy of the acromion was performed across the scapular spine and the coracoid through its base; an osteotomy of the clavicle was performed through the junction to the middle and distal thirds. The coracohumeral ligament was divided at the point of attachment to the humerus. The bone-ligament-bone unit was then removed en bloc. Once free from the cadaver, the specimen was inspected and the relationship of the CAL and deltoid tendon insertions into the acromion was studied. The specimen was then decalcified. To standardize the sagittal sections for histologic examination, they were taken through the anterior acromion midway between the lateral margin of the acromion and the acromial articulation of the AC joint. Sagittal sections were also taken through each AC joint. The sections were then embedded in paraffin and stained with hematoxylin and eosin. The site of insertion of the CAL and the deltoid tendon into the anterior acromion and AC joint was then studied by means of light microscopy. In the second part of the study, an arthroscopic anterior acromioplasty was performed on each of 10 fresh cadaver shoulder specimens. The cadavers ranged in age from 72 to 83 years (average, 76 years); none had rotator cuff tears or palpable anterior acromial osteophytes. The technique used was identical to that used in our clinical practice. This method involves a posterior burr portal and a lateral scope portal.2 We believe that, as reported by Ogilvie-Harris et al,20 a posterior burr portal permits resec-
tion of the anterior lip of the acromion with more precision than a lateral burr portal. The inferior and anterior acromion was burred away until an adequate decompression was achieved. The specimens were then dissected in the same fashion as the nonoperated cadavers, studied macroscopically, and, after preparation, examined with light microscopy.
RESULTS Nonoperated Specimens Macroscopic examination of the CAL and deltoid attachments to the acromion revealed that the most superiorly placed fibers blended with the overlying deltoid. It was noted that if the deltoid is reflected superiorly, it is tethered to the underlying CAL near its acromial end by fibrous tissue and there is no clear junction between the CAL and deltoid attachments. The inferiorly placed fibers of the CAL extended onto the inferior surface of the acromion. The more medial fibers inserted into the capsule of the AC joint. Dissecting the CAL, we found that the medial and lateral margins of the CAL were not well defined, appearing to be continuous with the clavipectoral fascia medially and the fascia on the undersurface of the deltoid laterally. This lateral extension of the CAL, blending with the fascia on the deep surface of the deltoid, extended beyond the lateral margin of the acromion. At its coracoid end, the CAL also blended with the tendons of biceps and coracobrachialis muscles. Under light microscopy, sagittal sections of the attachment of the CAL and deltoid to the acromion (Figure 1) revealed that the insertion of the CAL into the acromion was via fibrocartilage and periosteum. The
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Figure 2 Sagittal section of acromioplasty specimen anterior acromion (A) has been burred away; division of inferior fibers of coracoacromial ligament (CAL) is shown. CAL gains attachment to acromion by CALD-periosteal complex (CALDPC).
more superior collagen fibers of the CAL could be seen to blend with collagen fibers of the tendinous insertion of the deltoid before both of these structures gained attachment to the periosteum of the acromion. Operated Specimens In the operated specimens, the inferior and anterior acromion had been burred away. The fibers of the CAL inserting into the inferior part of the acromion were completely divided. The remaining fibers of the CAL gained attachment to the anterior part of the acromion immediately superior to the burred area. The attachment of the anterior deltoid to the acromion remained intact in all cases, and the deltoid could not be avulsed with strong traction. The medial fibers of the CAL, inserting into the inferior surface of the AC joint capsule, and the lateral fibers of the CAL, blending with the deltoid fascia, remained intact macroscopically. Microscopic examination of the operated specimens revealed that the fibers of the CAL gained attachment to the acromion by blending with the overlying deltoid tendon and a bridge of remaining acromial periosteum; we term this structure the coracoacromial-deltoid-periosteal complex (CALD-periosteal complex; Figure 2).
DISCUSSION The CAL has an intimate relationship with the deltoid at the acromial attachment. On microscopic examination, collagen fibers of the CAL and deltoid were found to coalesce at their attachment to the periosteum of the acromion. This study has demonstrated that the part of the CAL that attaches to the acromion is attenuated but
not divided when an arthroscopic acromioplasty is performed through use of a posterior burr portal. After acromioplasty, the CAL gains attachment to the anterior acromion by a bridge of deltoid tendon and periosteum—the CALD-periosteal complex. The more medial fibers of the CAL, inserting into the AC joint, and the lateral fibers, blending with the deltoid fascia, are not affected by the arthroscopic anterior acromioplasty with the posterior burr portal technique. However, arthroscopic resection of the medial end of the clavicle to treat symptomatic AC joint osteoarthritis is sometimes performed concurrently with an arthroscopic anterior acromioplasty. This would further attenuate the attachment of the acromial end of the CAL. Preservation of the CAL in arthroscopic acromioplasty is controversial. There is a growing body of evidence that the CAL is an important anatomical and functional structure.5,12,16,17,23,24 To what extent function of the CAL is altered by the acromioplasty with the posterior burr portal technique is not known, but we believe that given the potential important functions of the CAL, it is preferable to preserve this structure. This may be particularly important in those shoulders with large rotator cuff tears in which rotator cuff function as an active primary restraint to superior translation of the humeral head is less effective.5 Arthroscopic acromioplasty also results in attenuation of the anterior fibers of the deltoid that insert into the acromion, some of the tendon gaining attachment to the acromion by a periosteal bridge (forming part of the CALD-complex). Kumar et al14 noted that only 25% of the anterior deltoid arises from the acromion. Detaching
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some of the anterior deltoid from the acromion does not appear to have a detrimental effect on the clinical outcome after arthroscopic acromioplasty4,8; however, the shoulder is probably weakened in flexion. Our study has confirmed that the CAL is preserved in an attenuated form after arthroscopic acromioplasty when this is performed with a burr introduced through a posterior portal. The anterior fibers of deltoid arising from the acromion are also attenuated. After acromioplasty, the acromial attachment of the CAL and some of the anterior fibers of the deltoid tendon gain attachment to the acromion by the CALD-periosteal complex. The clinical effect of leaving the CAL intact when an acromioplasty is performed is not known. A prospective study of the clinical results with arthroscopic acromioplasty in which the CAL is left intact is currently in progress. REFERENCES 1. Bigliani LU, Rodsky MW, Newton PD, O’Boyle MJ, Pollock RG, Flatow EL. Arthroscopic coracoacromial ligament resection for impingement in the overhead athlete [abstract]. J Shoulder Elbow Surg 1994;3:S73. 2. Caspari RB, Thal RA. A technique for arthroscopic subacromial decompression. Arthroscopy 1992;8:23-30. 3. Edelson JG, Luchs J. Aspects of CAL anatomy of interest to the arthroscopic surgeon. Arthroscopy 1995;11:715-9. 4. Ellman H. Arthroscopic subacromial decompression: analysis of one to three year results. Arthroscopy 1987;3:173-81. 5. Flatow EL, Kelkar R, Raimondo RA, Wang VM, Pollock RG, Pawluk RJ, et al. Active and passive restraints against superior humeral translation: the contributions of the rotator cuff, the biceps tendon, and the coracoacromial arch [abstract]. J Shoulder Elbow Surg 1996;5:S111. 6. Flatow EL, Rodosky MW, Yamaguchi K, Self EB, Pollock RG, Bigliani LU. Coracoacromial ligament preservation in rotator cuff surgery [abstract]. J Shoulder Elbow Surg 1996;5:S78. 7. Freidman RJ, Bonutti PM, Genez BM, Norfray JF. Subcoracoid impingement syndrome [abstract]. J Shoulder Elbow Surg 1994;3:S30.
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8. Gartsman GM, Blair ME, Philip C, Noble PC, Bennett JB, Tullos HS. Arthroscopic subacromial decompression: an anatomical study. Am J Sports Med 1988;16:48-50. 9. Gartsman GM. Arthroscopic acromioplasty for lesions of the rotator cuff. J Bone Joint Surg Am 1990;72:169-80. 10. Ha’eri GB, Wiley AM. Shoulder impingement syndrome: results of operative release. Clin Orthop 1982;168:128-32. 11. Harris JE, Blackney MC. The anatomy and function of the corco-acromial ligament. J Shoulder Elbow Surg 1993;S6-S12. 12. Holt ME, Allibone RO. Anatomic variants of the coracoacromial ligament. J Shoulder Elbow Surg 1995;4:370-5. 13. Johansson JE, Barrington TW. Coracoacromial ligament division. Am J Sports Med 1984;12:138-41. 14. Kumar VP, Satru K, Liu J, Shen Y. The anatomy of the anterior origin of the deltoid. J Bone Joint Surg Br 1997;79B:680-3. 15. McMinn RMH, editor. Last’s anatomy: regional and applied. 8th ed. London: Churchill Livingstone; 1988. 16. Liebermann J, Reichelt A. The function of the coracoacromial ligament. Acta Anat 1988;131:140-5. 17. Moorman CT, Deng XH, Warren RF, Torzilli PA, Wickiewicz TL. The coracoacromial ligament: is it the appendix of the shoulder? [abstract]. J Shoulder Elbow Surg 1996;5:S9. 18. Neer CS. Anterior acromioplasty for the chronic impingement syndrome in the shoulder: a preliminary report J Bone Joint Surg 1972;54A:41-50. 19. Neer CS. Impingement Lesions. Clin Orthop 1983;173:70-7. 20. Ogilvie-Harris DJ, Demaziere A, Fitsialos D, Stevens JK. Arthroscopic acromioplasty: the superiority of the posterior portal over the lateral portal. Orthop Clin North Am 1993;24:153-9. 21. Penny JN, Welsh RP. Shoulder impingement syndromes in athletes and their surgical management. Am J Sports Med 1981;9:11-5. 22. Rockwood CA, Lyons FR. Shoulder impingement syndrome: diagnosis, radiographic evaluation, and treatment with a modified Neer acromiolplasty. J Bone Joint Surg 1993;75A:409-24. 23. Salter GE, Nasca R J, Shelley BS. Anatomical observations on the acromioclavicular joint and supporting ligaments. Clin Orthop 1986;228. 24. Soslowski LJ, Charlene H, Shawn PJ, Carpenter JE. Geometric and mechanical properties of the coracoacromial ligament and their relationship to rotator cuff disease. CIin Orthop 1994;304:10-7. 25. Walch G, Boileau P, Noel E, Donell ST. Impingement of the deep surface of the supraspinatus tendon on the posterosuperior glenoid rim: an arthroscopic study. J Shoulder Elbow Surg 1993;1:238-45.
This study defines the normal anatomical relationships among the coracoacromial ligament, the deltoid, and the acromion in cadavers. The effect of arthroscopic acromioplasty on the acromial attachments of the coracoacromial ligament and the anterior fibers of the deltoid was also studied. After arthroscopic acromioplasty, the fibers of coracoacromial ligament and overlying deltoid inserting into the anterior part of the acromion remained attached to the acromion by a bridge of tissue composed of periosteum and collagen fibers of the coracoacromial ligament and deltoid tendon. We have called this the coracoacromialdeltoid-periosteal complex; it has not previously been described. This study demonstrates that arthroscopic acromioplasty preserves the acromial attachment of the coracoacromial ligament and the anterior fibers of the deltoid. (J Shoulder Elbow Surg 2000;9:491-4.)
S
ubacromial impingement syndrome is a common cause of shoulder pain. The acromion, coracoacromial ligament (CAL),1,13,21 acromioclavicular (AC) joint, coracoid,7 and greater tuberosity of the humerus10 have all been implicated in subacromial impingement. Acromioplasty, division of the CAL, and shaving of the greater tuberosity10 have all been performed to treat this syndrome. The CAL has a number of functions, including superior restraint of the glenohumeral joint5,15,17 and stabilization of the acromion16 and the AC joint.23 Flatow et al5 and Moorman et al17 have reported that the rotator cuff and the long head of biceps are the primary structures preventing superior subluxation of the humeral head and that the CAL is a final restraint. They concluded that aggressive decompression in the presence of an unrepaired or recurrent tendon defect may potentially impair shoulder function. These studies emphaFrom the Department of Orthopaedics, Flinders Medical Centre, Bedford Park (Drs Hunt and Krishnan), and the Institute of Medical and Veterinary Science, Adelaide (Dr Moore); South Australia, Australia. Reprint requests: J. Krishnan, FRACS, Department of Orthopaedics, Flinders Medical Centre, Bedford Park, South Australia, Australia. Copyright © 2000 by Journal of Shoulder and Elbow Surgery Board of Trustees. 1058-2746/2000/$12.00 + 0 32/1/109319 doi:10.1067/mse.2000.109319
sized that the CAL is not a vestigial structure but rather an important stabilizing structure and should be spared when possible. The anatomy of the CAL has been studied by a number of authors.3,11,23,24 The CAL has a variable morphology3,11,22,23; it is described as Y-shaped, quadrangular, or multiply banded. In its most common form, 2 bands form a Y-shaped structure12,24; the bands, classified as posteromedial and anterolateral, converge from the coracoid origin and blend midway to the acromial attachment. The CAL has fibers that insert into the anterior and inferior surface of the acromion. These also blend with the inferior surface of the AC joint.24 The CAL and deltoid attachments to the anterior acromion are intimately related. However, the gross anatomical and histologic relationship of the CAL and deltoid attachments to the anterior acromion has not been well defined. Arthroscopic anterior acromioplasty has gained wide acceptance in treating those patients with subacromial impingement syndrome,9 the results being comparable to those obtained through use of open acromioplasty,4,9 with arguably reduced morbidity. Division of the CAL during arthroscopic acromioplasty is controversial, Ellman4 and Gartsman9 being proponents. Flatow et al5 and Moorman et al17 believe that the CAL should be preserved in the presence of an irreparable cuff tear. In open anterior acromioplasty as described by Neer18 and in the modified Neer acromioplasty as described by Rockwood and Lyons,22 the CAL and deltoid attachments to the acromion are completely detached from the acromion. The CAL is resected and the deltoid is reattached to the acromion. The effect of arthroscopic acromioplasty on the anterior fibers of deltoid has recently been reported by Kumar et al14; however, some detachment of the anterior fibers of the deltoid occurred when mock arthroscopic acromioplasties were performed, and Kumar et al concluded that this did not compromise function. This was supported by the favorable clinical results of arthroscopic acromioplasty.4,9 The present study defines the normal histologic and gross anatomical relationships among the CAL, the deltoid, and the acromion in cadavers. The effect of arthroscopic acromioplasty on the acromial attachments of the CAL and the anterior fibers of the deltoid was also studied.
491
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Hunt, Moore, and Krishnan
J Shoulder Elbow Surg November/December 2000
Figure 1 Sagittal section of anterior acromion (A) shows attachments of deltoid (D) and coracoacromial ligament (CAL).
METHODS In the first part of the study, we examined the normal anatomy of the CAL in 10 fresh cadaver shoulder specimens. The cadavers ranged in age from 68 to 85 years (average, 72 years). None of the specimens had rotator cuff tears or palpable anterior acromial osteophytes. The skin and subcutaneous tissue was removed from the specimen. The deltoid was divided through use of a transverse incision 3 cm below its origin from the acromion. An osteotomy of the acromion was performed across the scapular spine and the coracoid through its base; an osteotomy of the clavicle was performed through the junction to the middle and distal thirds. The coracohumeral ligament was divided at the point of attachment to the humerus. The bone-ligament-bone unit was then removed en bloc. Once free from the cadaver, the specimen was inspected and the relationship of the CAL and deltoid tendon insertions into the acromion was studied. The specimen was then decalcified. To standardize the sagittal sections for histologic examination, they were taken through the anterior acromion midway between the lateral margin of the acromion and the acromial articulation of the AC joint. Sagittal sections were also taken through each AC joint. The sections were then embedded in paraffin and stained with hematoxylin and eosin. The site of insertion of the CAL and the deltoid tendon into the anterior acromion and AC joint was then studied by means of light microscopy. In the second part of the study, an arthroscopic anterior acromioplasty was performed on each of 10 fresh cadaver shoulder specimens. The cadavers ranged in age from 72 to 83 years (average, 76 years); none had rotator cuff tears or palpable anterior acromial osteophytes. The technique used was identical to that used in our clinical practice. This method involves a posterior burr portal and a lateral scope portal.2 We believe that, as reported by Ogilvie-Harris et al,20 a posterior burr portal permits resec-
tion of the anterior lip of the acromion with more precision than a lateral burr portal. The inferior and anterior acromion was burred away until an adequate decompression was achieved. The specimens were then dissected in the same fashion as the nonoperated cadavers, studied macroscopically, and, after preparation, examined with light microscopy.
RESULTS Nonoperated Specimens Macroscopic examination of the CAL and deltoid attachments to the acromion revealed that the most superiorly placed fibers blended with the overlying deltoid. It was noted that if the deltoid is reflected superiorly, it is tethered to the underlying CAL near its acromial end by fibrous tissue and there is no clear junction between the CAL and deltoid attachments. The inferiorly placed fibers of the CAL extended onto the inferior surface of the acromion. The more medial fibers inserted into the capsule of the AC joint. Dissecting the CAL, we found that the medial and lateral margins of the CAL were not well defined, appearing to be continuous with the clavipectoral fascia medially and the fascia on the undersurface of the deltoid laterally. This lateral extension of the CAL, blending with the fascia on the deep surface of the deltoid, extended beyond the lateral margin of the acromion. At its coracoid end, the CAL also blended with the tendons of biceps and coracobrachialis muscles. Under light microscopy, sagittal sections of the attachment of the CAL and deltoid to the acromion (Figure 1) revealed that the insertion of the CAL into the acromion was via fibrocartilage and periosteum. The
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Figure 2 Sagittal section of acromioplasty specimen anterior acromion (A) has been burred away; division of inferior fibers of coracoacromial ligament (CAL) is shown. CAL gains attachment to acromion by CALD-periosteal complex (CALDPC).
more superior collagen fibers of the CAL could be seen to blend with collagen fibers of the tendinous insertion of the deltoid before both of these structures gained attachment to the periosteum of the acromion. Operated Specimens In the operated specimens, the inferior and anterior acromion had been burred away. The fibers of the CAL inserting into the inferior part of the acromion were completely divided. The remaining fibers of the CAL gained attachment to the anterior part of the acromion immediately superior to the burred area. The attachment of the anterior deltoid to the acromion remained intact in all cases, and the deltoid could not be avulsed with strong traction. The medial fibers of the CAL, inserting into the inferior surface of the AC joint capsule, and the lateral fibers of the CAL, blending with the deltoid fascia, remained intact macroscopically. Microscopic examination of the operated specimens revealed that the fibers of the CAL gained attachment to the acromion by blending with the overlying deltoid tendon and a bridge of remaining acromial periosteum; we term this structure the coracoacromial-deltoid-periosteal complex (CALD-periosteal complex; Figure 2).
DISCUSSION The CAL has an intimate relationship with the deltoid at the acromial attachment. On microscopic examination, collagen fibers of the CAL and deltoid were found to coalesce at their attachment to the periosteum of the acromion. This study has demonstrated that the part of the CAL that attaches to the acromion is attenuated but
not divided when an arthroscopic acromioplasty is performed through use of a posterior burr portal. After acromioplasty, the CAL gains attachment to the anterior acromion by a bridge of deltoid tendon and periosteum—the CALD-periosteal complex. The more medial fibers of the CAL, inserting into the AC joint, and the lateral fibers, blending with the deltoid fascia, are not affected by the arthroscopic anterior acromioplasty with the posterior burr portal technique. However, arthroscopic resection of the medial end of the clavicle to treat symptomatic AC joint osteoarthritis is sometimes performed concurrently with an arthroscopic anterior acromioplasty. This would further attenuate the attachment of the acromial end of the CAL. Preservation of the CAL in arthroscopic acromioplasty is controversial. There is a growing body of evidence that the CAL is an important anatomical and functional structure.5,12,16,17,23,24 To what extent function of the CAL is altered by the acromioplasty with the posterior burr portal technique is not known, but we believe that given the potential important functions of the CAL, it is preferable to preserve this structure. This may be particularly important in those shoulders with large rotator cuff tears in which rotator cuff function as an active primary restraint to superior translation of the humeral head is less effective.5 Arthroscopic acromioplasty also results in attenuation of the anterior fibers of the deltoid that insert into the acromion, some of the tendon gaining attachment to the acromion by a periosteal bridge (forming part of the CALD-complex). Kumar et al14 noted that only 25% of the anterior deltoid arises from the acromion. Detaching
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some of the anterior deltoid from the acromion does not appear to have a detrimental effect on the clinical outcome after arthroscopic acromioplasty4,8; however, the shoulder is probably weakened in flexion. Our study has confirmed that the CAL is preserved in an attenuated form after arthroscopic acromioplasty when this is performed with a burr introduced through a posterior portal. The anterior fibers of deltoid arising from the acromion are also attenuated. After acromioplasty, the acromial attachment of the CAL and some of the anterior fibers of the deltoid tendon gain attachment to the acromion by the CALD-periosteal complex. The clinical effect of leaving the CAL intact when an acromioplasty is performed is not known. A prospective study of the clinical results with arthroscopic acromioplasty in which the CAL is left intact is currently in progress. REFERENCES 1. Bigliani LU, Rodsky MW, Newton PD, O’Boyle MJ, Pollock RG, Flatow EL. Arthroscopic coracoacromial ligament resection for impingement in the overhead athlete [abstract]. J Shoulder Elbow Surg 1994;3:S73. 2. Caspari RB, Thal RA. A technique for arthroscopic subacromial decompression. Arthroscopy 1992;8:23-30. 3. Edelson JG, Luchs J. Aspects of CAL anatomy of interest to the arthroscopic surgeon. Arthroscopy 1995;11:715-9. 4. Ellman H. Arthroscopic subacromial decompression: analysis of one to three year results. Arthroscopy 1987;3:173-81. 5. Flatow EL, Kelkar R, Raimondo RA, Wang VM, Pollock RG, Pawluk RJ, et al. Active and passive restraints against superior humeral translation: the contributions of the rotator cuff, the biceps tendon, and the coracoacromial arch [abstract]. J Shoulder Elbow Surg 1996;5:S111. 6. Flatow EL, Rodosky MW, Yamaguchi K, Self EB, Pollock RG, Bigliani LU. Coracoacromial ligament preservation in rotator cuff surgery [abstract]. J Shoulder Elbow Surg 1996;5:S78. 7. Freidman RJ, Bonutti PM, Genez BM, Norfray JF. Subcoracoid impingement syndrome [abstract]. J Shoulder Elbow Surg 1994;3:S30.
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