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Bony changes of the glenoid as a consequence of shoulder instability
Bony changes of the glenoid as a consequence of shoulder instability J. G. Edelson, MD, FAAOS, Tiberias, Israel
Among 500 skeletons of mature individuals, 27 showed signs of shoulder instability as indicated by the presence of a glenoid rim avulsion fracture, a bony Bankart lesion, with an anterior or posterior Hill-Sachs defect. Twenty-two of these glenoid lesions were anterior, and five were posterior. This is a higher prevalence than reported in clinical studies. With few exceptions the pathologic changes in the bony glenoid were well circumscribed and not found in conjunction with diffuse arthritic changes. These findings do not support prophylactic shoulder stabilization to avoid the development of arthritic changes of a generalized and major degree. (J ShouLDERELBOWSuRe 1996;5:293-8.) B o n y changes in the head of the humerus as a result of shoulder dislocation or subluxation (HillSachs or reverse Hill-Sachs lesions) are well documented in the literature 3' 12, 18 both as to morbid anatomy r3 and radiographic characteristics. 8' 9 Changes on the glenoid side of the joint are less easily seen with standard diagnostic studies, 7 and the actual pathologic anatomy, the bony Bankart lesion/is often not well visualized even at the time of surgery. In this investigation of a large number of skeletal specimens, relatively predictable types of glenoid involvement in shoulder instability were found. The anatomic makeup of these lesions is of practical interest to the operating surgeon. MATERIAL AND METHODS A total of 500 skeletons of mature adults 40 years of age or older from the Terry Collection of the Smithsonian Museum of Natural History in Washington, D.C., were examined. This collection was compiled from the Saint Louis, Missouri, metropolitan area in the early part of this century, and age, race, and sex were documented for the specimens. No clinical data are available. From the Department of Orthopedic Surgery, Poriya Hospilal. 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. Reprint requests: J. G. Eddson, MD, FAAOS, Kibbutz Deganya Bet DN. Emek Hayarden, Israel 15130. Copyright @ 1996 by Journal of Shoulder and FJbow Surgery Board of Trustees. 1058-2746/96/$5.00 + 0 3211174056
To approach a clinical situation as closely as possible, specimens were considered to demonstrate instability only if they displayed both a bony Bankart-like lesion of the anterior or posterior glenold rim and a concomitant Hill-Sachs or reverse Hill-Sachs lesion of the humeral head. Lesions on one side of the joint only were not included. However, some of these latter lesions are referred to in this study to recognize the occurrence of unilateral glenoid side or humeral head involvement as a consequence of shoulder instability. Observations. There were 27 (5.4%) examples of specimens with dislocations by our criteria. Twenty-two were anterior, and five (1%) were posterior. In two dramatic cases the anterior lesions appeared to have resulted from fixed dislocations. In the first of these, the glenoid was severely involved, with crushing and thinning to approximately one half of its original substance (Figure 1). In contrast, in the second case little involvement of the true glenoid was seen; a new pseudoglenoid had formed without substantial injury to the original joint cavity (Figure 2). In the more traditional presentation the rim lesions were usually well healed to the scapular neck. This formed a bony buttress anterior to the glenoid face (Figure 3) with a small gap or minimal step-off (Figure 4). In only one case was the joint affected by a generalized degenerative process involving both the glenoid and the humeral head. This was in an unusual presentation of bilateral anterior dislocations (Figure 5, A) with the humeral heads display293
294
J. Shoulder Elbow Surg. July~August 1996
Edelson
Figure 1 Bony changes after fixed anterior dislocation. In 65-year-old woman (A) lateral and (B) anterior view of head in dislocated postition. C, Crushed and flattened glenoid. D, Large Hill-Sachs lesion on humeral head.
Figure 2 A, Left scapula in 58-year-old man. Anterior view of lypical pseudogJenoid of fixed dislocation. In contrast to Figure 1, original gbnoid is relatively well preserved (B) in this specimen. ing symmetric changes of "primary" osteoarthritis2 (Figure 5, B). Posterior dislocations produced glenoid lesions similar to the anterior ones. Again, damage was usually peripheral and well circumscribed (Figure 6). No cases of generalized joint degeneration occurred in association with the posterior dislocations.
Isolated glenoid rim lesions unaccompanied by Hill-Sachs or reverse Hill-Sachs defects in the head were noted posteriorly in three cases and anteriorly in six cases. In a similar vein, in seven cases anterior and in three cases posterior Hil}-Sachs defects were unaccompanied by any significant glenoid rim lesions. By our inclusion criteria these single lesions were not counted for the purposes of
J. Shoulder Elbow Surg. Volume 5, Number 4
Figure 3 A, Well-healed anterior glenoid rim fracture sits proud of remaining rim margin but smoothly accommodates humeral head (B).
Figure 4 A, Unusual bilateralpresentation of anterior rim defects B! Humeral heads display the typical "beard" osteophyte of primary osteoarthritis
Edelson
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296
Edelson
Figure $ A, Posteriordislocation with (B) reverse HillSachs Jesion (arrows) and (C) posterior Bankart lesion. this study. Nonetheless they illustrate the status of the glenoid in probable cases of shoulder instability. In addition, in one posterior fracture dislocation of the head the glenoid cavity appeared normal. DISCUSSION Exception may be taken to the criteria for inclusion or exclusion in this work. Clearly dislocations and subluxations are principally soft-tissue problems, i, 14 and the true numbers in our population group must be higher than the prevalence figure of 5.4% demonstrated in this study. This figure in itself represents a higher prevalence than is generally recognized clinically. Hoevlius 1~ reported an incidence of glenohumeral dislocations of 1.7% in the Swedish population, and other clinical studies suggest even lower figures.l~' 19 Comparable studies in this regard are difficult to find, because the nature of our skeletal material does not allow rigorous comparison with incidence and prevalence figures derived from clinical surveys. However, it would appear that bony evidence of instability is more common than the reporting of clinical cases. We have also demonstrated a much higher
J. Shoulder Elbow Surg. July~August 1996
proportion of posterior pathologic condition than is usually seen. 17 Statistical reports as to the incidence of posterior instability or frank posterior dislocation have not been documented, to the best of our knowledge, in large population studies. However, these are generally conceived to be rare events composing, in the case of dislocations, from 1.5% to 3.8% of all shoulder dislocations. TM In our specimens shoulder instability appeared to produce only relatively discrete glenoid-side changes. The general impression from the healed rim lesions, both anteriorly and posteriorly, was that of a localized, "natural" bone block. These observations must be tempered with the knowledge that the cartilaginous articular surfaces of these specimens are no longer available to us and may have been involved with more extensive and diffuse degenerative changes. There were two exceptions among our specimens to the localized nature of the glenoid side bony changes. One was the fixed dislocations pictured in Figure 1. Here, extensive damage was most probably initiated by a substantial glenoid fracture. By contrast, the fixed dislocation shown in Figure 2 did not demonstrate a major glenoid pathologic condition. It would appear that when or if surgery is considered in cases of chronic dislocations, a careful evaluation of the status of the glenoid should be sought with computed axial tomography scanning '~ or magnetic resonance imaging7 ~ The second example of more generalized joint disease was the unusual case of bilateral anterior dislocations (Figure 5). Here a "primary" osteoarthritic process may have been provoked by trauma, ~ or the pathologic changes in the heads may have preceded the dislocations. In either case the changes in the glenoids themselves were quite localized. Although we do not know the dates and details of shoulder instability in these individuals relative to their deaths, the overwhelming majority of these specimens were from persons 45 years of age or older. If, as is usually the case, most of these dislocations took place in youth, these well-healed bones most probably represent a form of long-term follow-up illustrating the focal nature of the degenerative consequences of shoulder instability on the glenoid. Recently, long-term clinical follow-up studies have demonstrated the lack of significant degenerative joint changes in persons with nontraumatic multidirectional instability of the shoulder who have not had surgery. ~ It is surprising that little long-term clinical data are available on the
J. Shoulder Elbow Surg. Volume 5, Number 4
Edelson
297
Figure 6 Anterior rim fractures in continuily with original glenoid surface, which is not involved by diffuse degeneration.
degenerative consequences of the more common variety of unoperated instabilities pictured here/ In light of the localized nature of the bony findings in this study, long-term clinical studies are needed on the natural history of these instabilities so that we may counsel our patients more knowledgeably as to the consequences of their disorders. In addition, the bony anatomic makeup demonstrated here is often obscured at the time of surgery by torn and displaced labral tissues. An appreciation of the relatively consistent nature of the bony Bankart lesion pictured in these specimens may be of assistance to the surgeon at operation in addressing the glenoid, both in terms of bony and soft-tissue repair. I thank Dr. David R. Hunt of the Department of Anthropology, Smithsonian Institute, Washington D.C., and Jaymie L. Brauer, Department of Anthropology, American Museum of Natural History, New York, for their invaluable assistance in examining their museum collections, Frank Martucci for his superb photographic work, and Hadas Sasson for her technical assistance. REFERENCES 1. Bankart ASB. The pathology and treatment of recurrent dislocation of the shoulder joint. Br j Surg 1938;26:23-9.
2. Cofield RH. Degenerative and arthritic problems of the glenohumeral oint. In: Rockwood Jr CA, Matsen III FA, editors. The shouder. Vo 2. Phiadephia: WB Saunders, 1990:678 749. 3. ConnoJly JF. Humeral head defects associated with shoulder dislocations: their diagnostic and surgical significance. AAOS Instr Course Lect 1972;21-42. 4. Dalton SE, Synder SJ. Glenohumeral instabili V. Baillierre's Olin Rheumatol 1989; 3:3:511-34. 5. DePalma AF. Surgery of the shoulder. Philadelphia: JB Lippincott Co, 1983:463. 6. Doherly M, Watt I, Dieppe R Influence of primary generalised osteoarthritis on development of secondary osteoarthritis. Lancet 1983;2:8-11. 7. Gazidly DF, Godeneche ]L. The use of coracoid transfer for recurrent anterior gJenohumeral instabilily. In: Watson MS, editor. Surgical disorders of the shoulder. Edinburgh: Churchill Livingston, ] 991:355-62. 8. Hermodsson h Roentgendogical studies of traumatic and recurrent anterior and inferior dislocations of the shoulder joint (English translation, Moserey HF, Overgaard B, 1963) Montreal: McGill Llniversily Press, 1934. 9. Hill HA, Sachs MD. The grooved defect of the humeral head. A frequently unrecognized complication of the shoulder joint. Radiology 1940;35:690. 10. Hoevlius L Incidence of shoulder dislocation in Sweden. Clin Orthop 1982;166:127-31. 11. Huber H, Gerber C. Voluntary subluxation of the shoulder in children, j Bone Joint Surg Br 1994;76B:118-22. 12. Matsen FA, Thomas SO, Rockwood CA. Interior gleno-
298
13. 14. 15. 16.
J. Shoulder Elbow Surg. July~August 1996
Edelson
humeral instabili~. In: Rockwood CA, Matsen III FA, editors. The shouJden Philadelphia: WB Saunders, 1990;14:52627. McLaughlin JL Recurrent anterior dislocation of the shoulder. Part 1: Morbid anatomy. Am J Surg 1960;99:628-32. Moseley HF. Shoulder lesions. Baltimore: The Williams and Wilkins Co., 1969:189. Nordqvisl A, PeterssonCJ. Incidence and causes of shoulder girdle injuries in an urban population. J Shoulder Elbow Surg 1995;4:107-12. Rafii M, Minkoff J, Bonamo J, et ah Computer tomography
17. 18. 19. 20.
(CT) arthography of shoulder instabilities in athletes. Am J Sports Med 1988;16:352-60. Rockwood CA Jr. Subluxations and dislocations about the shoulder. In: Rockwood Jr CA, Green DF editors, ffractures in adults. Vol I. Philadelphia:JB Lippincott Co, 1984:722-985. Rowe CR (editor). The shoulden New York: Churchill Livingston, 1988:166. Simonet WT, Cofield RH. Prognosis in anterior shoulder dislocation. Am J Sports Med 1984;12:19-24. Zlatkin MB. MRI of the shoulden New York: Raven Press, 1991:99-129.
Among 500 skeletons of mature individuals, 27 showed signs of shoulder instability as indicated by the presence of a glenoid rim avulsion fracture, a bony Bankart lesion, with an anterior or posterior Hill-Sachs defect. Twenty-two of these glenoid lesions were anterior, and five were posterior. This is a higher prevalence than reported in clinical studies. With few exceptions the pathologic changes in the bony glenoid were well circumscribed and not found in conjunction with diffuse arthritic changes. These findings do not support prophylactic shoulder stabilization to avoid the development of arthritic changes of a generalized and major degree. (J ShouLDERELBOWSuRe 1996;5:293-8.) B o n y changes in the head of the humerus as a result of shoulder dislocation or subluxation (HillSachs or reverse Hill-Sachs lesions) are well documented in the literature 3' 12, 18 both as to morbid anatomy r3 and radiographic characteristics. 8' 9 Changes on the glenoid side of the joint are less easily seen with standard diagnostic studies, 7 and the actual pathologic anatomy, the bony Bankart lesion/is often not well visualized even at the time of surgery. In this investigation of a large number of skeletal specimens, relatively predictable types of glenoid involvement in shoulder instability were found. The anatomic makeup of these lesions is of practical interest to the operating surgeon. MATERIAL AND METHODS A total of 500 skeletons of mature adults 40 years of age or older from the Terry Collection of the Smithsonian Museum of Natural History in Washington, D.C., were examined. This collection was compiled from the Saint Louis, Missouri, metropolitan area in the early part of this century, and age, race, and sex were documented for the specimens. No clinical data are available. From the Department of Orthopedic Surgery, Poriya Hospilal. 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. Reprint requests: J. G. Eddson, MD, FAAOS, Kibbutz Deganya Bet DN. Emek Hayarden, Israel 15130. Copyright @ 1996 by Journal of Shoulder and FJbow Surgery Board of Trustees. 1058-2746/96/$5.00 + 0 3211174056
To approach a clinical situation as closely as possible, specimens were considered to demonstrate instability only if they displayed both a bony Bankart-like lesion of the anterior or posterior glenold rim and a concomitant Hill-Sachs or reverse Hill-Sachs lesion of the humeral head. Lesions on one side of the joint only were not included. However, some of these latter lesions are referred to in this study to recognize the occurrence of unilateral glenoid side or humeral head involvement as a consequence of shoulder instability. Observations. There were 27 (5.4%) examples of specimens with dislocations by our criteria. Twenty-two were anterior, and five (1%) were posterior. In two dramatic cases the anterior lesions appeared to have resulted from fixed dislocations. In the first of these, the glenoid was severely involved, with crushing and thinning to approximately one half of its original substance (Figure 1). In contrast, in the second case little involvement of the true glenoid was seen; a new pseudoglenoid had formed without substantial injury to the original joint cavity (Figure 2). In the more traditional presentation the rim lesions were usually well healed to the scapular neck. This formed a bony buttress anterior to the glenoid face (Figure 3) with a small gap or minimal step-off (Figure 4). In only one case was the joint affected by a generalized degenerative process involving both the glenoid and the humeral head. This was in an unusual presentation of bilateral anterior dislocations (Figure 5, A) with the humeral heads display293
294
J. Shoulder Elbow Surg. July~August 1996
Edelson
Figure 1 Bony changes after fixed anterior dislocation. In 65-year-old woman (A) lateral and (B) anterior view of head in dislocated postition. C, Crushed and flattened glenoid. D, Large Hill-Sachs lesion on humeral head.
Figure 2 A, Left scapula in 58-year-old man. Anterior view of lypical pseudogJenoid of fixed dislocation. In contrast to Figure 1, original gbnoid is relatively well preserved (B) in this specimen. ing symmetric changes of "primary" osteoarthritis2 (Figure 5, B). Posterior dislocations produced glenoid lesions similar to the anterior ones. Again, damage was usually peripheral and well circumscribed (Figure 6). No cases of generalized joint degeneration occurred in association with the posterior dislocations.
Isolated glenoid rim lesions unaccompanied by Hill-Sachs or reverse Hill-Sachs defects in the head were noted posteriorly in three cases and anteriorly in six cases. In a similar vein, in seven cases anterior and in three cases posterior Hil}-Sachs defects were unaccompanied by any significant glenoid rim lesions. By our inclusion criteria these single lesions were not counted for the purposes of
J. Shoulder Elbow Surg. Volume 5, Number 4
Figure 3 A, Well-healed anterior glenoid rim fracture sits proud of remaining rim margin but smoothly accommodates humeral head (B).
Figure 4 A, Unusual bilateralpresentation of anterior rim defects B! Humeral heads display the typical "beard" osteophyte of primary osteoarthritis
Edelson
295
296
Edelson
Figure $ A, Posteriordislocation with (B) reverse HillSachs Jesion (arrows) and (C) posterior Bankart lesion. this study. Nonetheless they illustrate the status of the glenoid in probable cases of shoulder instability. In addition, in one posterior fracture dislocation of the head the glenoid cavity appeared normal. DISCUSSION Exception may be taken to the criteria for inclusion or exclusion in this work. Clearly dislocations and subluxations are principally soft-tissue problems, i, 14 and the true numbers in our population group must be higher than the prevalence figure of 5.4% demonstrated in this study. This figure in itself represents a higher prevalence than is generally recognized clinically. Hoevlius 1~ reported an incidence of glenohumeral dislocations of 1.7% in the Swedish population, and other clinical studies suggest even lower figures.l~' 19 Comparable studies in this regard are difficult to find, because the nature of our skeletal material does not allow rigorous comparison with incidence and prevalence figures derived from clinical surveys. However, it would appear that bony evidence of instability is more common than the reporting of clinical cases. We have also demonstrated a much higher
J. Shoulder Elbow Surg. July~August 1996
proportion of posterior pathologic condition than is usually seen. 17 Statistical reports as to the incidence of posterior instability or frank posterior dislocation have not been documented, to the best of our knowledge, in large population studies. However, these are generally conceived to be rare events composing, in the case of dislocations, from 1.5% to 3.8% of all shoulder dislocations. TM In our specimens shoulder instability appeared to produce only relatively discrete glenoid-side changes. The general impression from the healed rim lesions, both anteriorly and posteriorly, was that of a localized, "natural" bone block. These observations must be tempered with the knowledge that the cartilaginous articular surfaces of these specimens are no longer available to us and may have been involved with more extensive and diffuse degenerative changes. There were two exceptions among our specimens to the localized nature of the glenoid side bony changes. One was the fixed dislocations pictured in Figure 1. Here, extensive damage was most probably initiated by a substantial glenoid fracture. By contrast, the fixed dislocation shown in Figure 2 did not demonstrate a major glenoid pathologic condition. It would appear that when or if surgery is considered in cases of chronic dislocations, a careful evaluation of the status of the glenoid should be sought with computed axial tomography scanning '~ or magnetic resonance imaging7 ~ The second example of more generalized joint disease was the unusual case of bilateral anterior dislocations (Figure 5). Here a "primary" osteoarthritic process may have been provoked by trauma, ~ or the pathologic changes in the heads may have preceded the dislocations. In either case the changes in the glenoids themselves were quite localized. Although we do not know the dates and details of shoulder instability in these individuals relative to their deaths, the overwhelming majority of these specimens were from persons 45 years of age or older. If, as is usually the case, most of these dislocations took place in youth, these well-healed bones most probably represent a form of long-term follow-up illustrating the focal nature of the degenerative consequences of shoulder instability on the glenoid. Recently, long-term clinical follow-up studies have demonstrated the lack of significant degenerative joint changes in persons with nontraumatic multidirectional instability of the shoulder who have not had surgery. ~ It is surprising that little long-term clinical data are available on the
J. Shoulder Elbow Surg. Volume 5, Number 4
Edelson
297
Figure 6 Anterior rim fractures in continuily with original glenoid surface, which is not involved by diffuse degeneration.
degenerative consequences of the more common variety of unoperated instabilities pictured here/ In light of the localized nature of the bony findings in this study, long-term clinical studies are needed on the natural history of these instabilities so that we may counsel our patients more knowledgeably as to the consequences of their disorders. In addition, the bony anatomic makeup demonstrated here is often obscured at the time of surgery by torn and displaced labral tissues. An appreciation of the relatively consistent nature of the bony Bankart lesion pictured in these specimens may be of assistance to the surgeon at operation in addressing the glenoid, both in terms of bony and soft-tissue repair. I thank Dr. David R. Hunt of the Department of Anthropology, Smithsonian Institute, Washington D.C., and Jaymie L. Brauer, Department of Anthropology, American Museum of Natural History, New York, for their invaluable assistance in examining their museum collections, Frank Martucci for his superb photographic work, and Hadas Sasson for her technical assistance. REFERENCES 1. Bankart ASB. The pathology and treatment of recurrent dislocation of the shoulder joint. Br j Surg 1938;26:23-9.
2. Cofield RH. Degenerative and arthritic problems of the glenohumeral oint. In: Rockwood Jr CA, Matsen III FA, editors. The shouder. Vo 2. Phiadephia: WB Saunders, 1990:678 749. 3. ConnoJly JF. Humeral head defects associated with shoulder dislocations: their diagnostic and surgical significance. AAOS Instr Course Lect 1972;21-42. 4. Dalton SE, Synder SJ. Glenohumeral instabili V. Baillierre's Olin Rheumatol 1989; 3:3:511-34. 5. DePalma AF. Surgery of the shoulder. Philadelphia: JB Lippincott Co, 1983:463. 6. Doherly M, Watt I, Dieppe R Influence of primary generalised osteoarthritis on development of secondary osteoarthritis. Lancet 1983;2:8-11. 7. Gazidly DF, Godeneche ]L. The use of coracoid transfer for recurrent anterior gJenohumeral instabilily. In: Watson MS, editor. Surgical disorders of the shoulder. Edinburgh: Churchill Livingston, ] 991:355-62. 8. Hermodsson h Roentgendogical studies of traumatic and recurrent anterior and inferior dislocations of the shoulder joint (English translation, Moserey HF, Overgaard B, 1963) Montreal: McGill Llniversily Press, 1934. 9. Hill HA, Sachs MD. The grooved defect of the humeral head. A frequently unrecognized complication of the shoulder joint. Radiology 1940;35:690. 10. Hoevlius L Incidence of shoulder dislocation in Sweden. Clin Orthop 1982;166:127-31. 11. Huber H, Gerber C. Voluntary subluxation of the shoulder in children, j Bone Joint Surg Br 1994;76B:118-22. 12. Matsen FA, Thomas SO, Rockwood CA. Interior gleno-
298
13. 14. 15. 16.
J. Shoulder Elbow Surg. July~August 1996
Edelson
humeral instabili~. In: Rockwood CA, Matsen III FA, editors. The shouJden Philadelphia: WB Saunders, 1990;14:52627. McLaughlin JL Recurrent anterior dislocation of the shoulder. Part 1: Morbid anatomy. Am J Surg 1960;99:628-32. Moseley HF. Shoulder lesions. Baltimore: The Williams and Wilkins Co., 1969:189. Nordqvisl A, PeterssonCJ. Incidence and causes of shoulder girdle injuries in an urban population. J Shoulder Elbow Surg 1995;4:107-12. Rafii M, Minkoff J, Bonamo J, et ah Computer tomography
17. 18. 19. 20.
(CT) arthography of shoulder instabilities in athletes. Am J Sports Med 1988;16:352-60. Rockwood CA Jr. Subluxations and dislocations about the shoulder. In: Rockwood Jr CA, Green DF editors, ffractures in adults. Vol I. Philadelphia:JB Lippincott Co, 1984:722-985. Rowe CR (editor). The shoulden New York: Churchill Livingston, 1988:166. Simonet WT, Cofield RH. Prognosis in anterior shoulder dislocation. Am J Sports Med 1984;12:19-24. Zlatkin MB. MRI of the shoulden New York: Raven Press, 1991:99-129.