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The shoulder joint—Is it dislocated? Apparent dislocation of the shoulder joint
Clitt,Radiol. (1969) 20, 61-64
THE SHOULDER JOINT--IS IT D I S L O C A T E D ? APPARENT DISLOCATION OF THE SHOULDER JOINT D. E. M A R K H A M
a n d J. R O W L A N D *
from the Department of Radiology, Royal Hospital, SheffieM The p h e n o m e n o n of apparent dislocation of the shoulder j o i n t is described a n d illustrated with reference to clinical cases. The importance of accurate clinical a n d radiological differentiation between apparent a n d true dislocation of the shoulder is emphasised, in order to prevent unnecessary a n d abortive attempts at m a n i p u l a t i o n of apparently dislocated shoulders. A regime of conservative t r e a t m e n t of apparent dislocation is outlined. The various factors believed to contribute to apparent dislocation are discussed. The three m a i n causes are T r a u m a , Infection a n d Paralysis.
INTRODUCTION A condition which presents several of the clinical and radiological features of dislocation of the shoulder has been observed, b u t some of the criteria of true dislocation are absent. Although the condition is well k n o w n to experienced orthopaedic surgeons a n d radiologists, patients with this c o n d i t i o n are often m a n i p u l a t e d by inexperienced persons in the mistaken belief that true dislocation of the j o i n t is present. T w o cases in the present series were, i n fact, mistakenly m a n i p u lated. Only after these m a n i p u l a t i o n s h a d failed to produce either clinical or radiological i m p r o v e m e n t was it recognised that these patients did n o t have a true dislocation, b u t that a c o n d i t i o n of apparent dislocation was present. Since then, several cases with apparent dislocation have been recognised a n d have been successfully treated without m a n i p u l a tion. A selection of these patients are described a n d illnstrated below. CASE HISTORIES Case 1.--D.M., a 70 year-old woman was first seen on 17.11.66 one day after a fall in which she injured her left shoulder. Clinical examination showed all movements of the left shoulder to be limited, with swelling anterior to the joint. Radiographs showed a fracture with apparent dislocation of the shoulder joint (Fig. 1). After manipulation had been undertaken by the Casualty staff under general anaesthetic, radiographs showed no apparent change in position, though symptomatically the shoulder had improved when it was supported in a sling. On clinical re-examination on 18.11.66
it was considered that the shoulder was not dislocated. Aspiration of the joint yielded 15 ml. of blood. A radiograph with the patient supporting the injured shoulder showed that there was no dislocation (Fig. 2). The position 6 weeks after aspiration is shown in Fig. 3. Case 2.--V.O'H,, a 55 year-old woman fell on 10.10.65 and sustained a fracture of the neck of the humerus with apparent dislocation of the right shoulder (Fig. 4), After manipulation by a casualty officer, a radiograph of the shoulder showed no change in the apparent dislocation. The patient's general condition was poor. She had chronic bronchitis and emphysema, together with considerable pulmonary fibrosis from long-standingtuberculosis. No further active treatment was given to the injured joint. A portable radiograph on 25.11.65 showed the right shoulder joint to be reduced. Respiratory and circulatory failure supervened and the patient died on28.11.65. Case 3.--K.H., a 20 year-old female warehouse worker presented with a three week history of a painful, swollen left shoulder. There was no history of injury. On examination the patient was pyrexial and had a tachycardia. There was an effusion into the left shoulder joint, all movements of which were grossly limited. The joint was tender to palpation and the overlying skin was red and hot. A radiograph showed subluxation of the joint. The humeral head was below its normal position with consequent loss of parallelism between it and the glenoid (Fig. 5). Aspiration of the joint was performed and 20 ml. of pus removed. This aspiration resulted in clinical and radiographic improvement in the shoulder (Fig. 6). The left arm was supported in a sling and systemic antibiotics administered. The aspirate yielded a growth of Staph. Pyogenes on culture. Subsequent progress was uneventful. The subluxation did not recur. Full movements of the joint were regained within six weeks of her initial presentation. Case 4.--R.M., a 54 year-old housewife was known to be suffering from carcinoma of the bronchus with metastases
* Present address: Department Radiology, Clayton Hospital, Wakefield. 61
62
CLINICAL
RADIOLOGY
FIG. 1 FIG. 2 FIG. 1.--Case 1. Left Shoulder: Fracture of the neck of the humerus with avulsion of the greater tuberosity and apparent dislocation of the shoulder. Fie. 2.--Case 1. Left Shoulder: After aspiration of 15 mls. of blood-stained fluid the humeral head is more closely related to the glenoid fossa.
FIG. 3 FIG. 4 FIG. 3.--Case 1. Left Shoulder: Final position of the shoulder joint 6 weeks after the aspiration. FIG. 4.--Case 2. Right Shoulder: Fracture of the neck of the humerus with apparent dislocation of the shoulder joint.
in the bodies of the fifth and sixth cervical vertebrae. T h e - o f t h e cervical spine s h o w e d collapse o f the bodies o f C.5 and C.6. (Fig. 7). patient was referred on account of paraesthesiae a n d proW h e n seen six weeks later, the weakness of the muscles gressive weakness in t h e right a r m a n d h a n d . of the right shoulder h a d progressed to complete paralysis E x a m i n a t i o n showed gross i m p a i r m e n t of m o v e m e n t o f the shoulder as a result o f muscle weakness. There was a a n d t h e joint showed clinical evidence o f apparent disfull r a n g e o f passive m o v e m e n t . T e n d o n reflexes in the right location. This was confirmed by radiographs o f the shoulder (Fig. 8). T h e a p p a r e n t dislocation was " r e d u c e d " by the a r m were diminished a n d there was diminished~sensation in simple m e a s u r e o f s u p p o r t i n g the right a r m in a sling, the C.5 a n d C_6 d e r m a t o m e s . T h e r e was at this time n o T h e patient died f r o m carcinomatosis soon after her clinical evidence o f dislocation o f the right shoulder a n d radiographs o f the joint showed no abnormality. R a d i o g r a p h s second attendance.
THE SHOULDER
JOINT--IS
FIG. 5
63
IT D I S L O C A T E D . 9
FIG. 6
FI~, 5.--Case 3. Left Shoulder: Subluxation of the shoulder joint. Fro. 6.--Case 3. Left Shoulder: Position after aspiration of 20 ml. of pus.
FIG. 7
DISCUSSION True dislocation of the shoulder joint is an easily recognised and familiar syndrome giving classical clinical and radiographic findings. However, because the recognition of apparent dislocation depends so critically upon the appreciation' of all
the clinical and radiological signs of true dislocation, and thus the absence of s o m e in apparent dislocation, the criteria of true dislocation are included in tke text. There is usually a history of injury to, or in the vicinity of, the shoulder joint, and the patient
64
CLINICAL RADIOLOGY
complains of pain in, and limitation of movement of, the joint. Clinical examination reveals an alteration in the contour of the joint compared with the normal one. The affected arm is held away from the side and the patient is unable to bring the arm into contact with the trunk. There is no movement at the joint; only scapular movement remains. The affected arm appears longer than the normal side. On radiological examination, the humeral head is displaced medially and downwards, n o r m a l l y taking up a position antero-inferior to the coracoid process of the scapula (anterior sub-coracoid dislocation). Occasionally the humeral head is displaced downwards, medially and backwards, but such posterior dislocations are rare. The clinical syndrome of apparent dislocation differs in several respects from that of true dislocation. There is usually, but by no means always, a history of trauma (c.f. Cases 3 and 4). The patient complains of pain but this is rarely as severe as in true dislocation. Although there is apparent lengthening of the affected arm, coupled with an alteration of the normal contour of the shoulder joint, the arm can be brought into contact with the trunk and movement is possible at the shoulder but is restricted in all ,directions. There are significant differences in the radiographic appearances. In apparent dislocation the shoulder joint is dislocated in so far as contact between humerus and scapula is lacking. However, the humeral head takes up a position immediately below the glenoid, there being no significant anterior, posterior or medial displacement. There is always a considerable effusion into the shoulder joint. Thus, apparent rather than true dislocation exists if, on clinical examination, the arm on the affected side can be brought into contact with the trunk and some. movement is present at the shoulder, and if a radiograph shows no significant displacement of humeral head relative to the glenoid other than in a downward direction. The causes of apparent dislocation can be grouped into three; Trauma, Infection and Paralysis. Trauma is the most common cause of apparent dislocation and is usually found with an associated comminuted fracture of the surgical neck of the humerus. In this series the patients suffering from traumatic apparent dislocation have either been of advancing years or in a debilitated general condition from other causes. The three factors which appear to contribute to the production of apparent dislocation following trauma are poor muscle tone, the presence of a tense haemarthrosis and the absence of
any significant tear in the joint capsule. The latter factor has a two-fold action, namely, to contain the humeral head within the confines of the joint and also to distend and accommodate a tense haemarthrosis. It is well known that muscle tone is diminished in those muscles adjacent to a joint which contains any type of effusion. Coupled with a pre-existing general lack of muscle tone, as found in aged or debilitated patients, the general effect is to reduce muscle spasm and thus prevent any medial pull of the displaced humeral head. The downward displacement of the humeral head occurs under the influence of gravity, facilitated by capsular distension and unopposed by muscle tone. It is believed that the pressure of adequate muscle tone in young, fit persons is sufficient to oppose the pull of gravity and accounts for the fact that traumatic apparent dislocation has not been encountered in that category of patient. The importance of these three contributory factors is emphasised by the demonstration of reduction of apparent dislocation by joint aspiration and support of the affected arm in a sling. Pyogenic arthritis is always accompanied by joint effusion. This has exactly the same effect on the capsule of the shoulder as referred to in traumatic haemarthrosis. It Mso has the effect, as in other joints similarly affected, of causing diminution in muscle mass and tone. The mechanism of apparent dislocation is, therefore, basically the same as in that due to trauma. The normal stability of the shoulder joint is largely due to the tone of its surrounding muscles. The capsule of the joint is lax, thus allowing a wide range of movement. It is, thus, easily appreciated that complete absence of muscle torte leads t o instability in the joint. In a case such as that described (Case 4) where paralysis is due to spinal cord or nerve root damage, there is also a diminution in joint proprioception. The effect of gravity is thus unopposed, and subluxation or apparent dislocation ensues. However, in the absence of capsular tear, the head of the humerus is still contained within the joint. Paralysis of the surrounding muscles prevents any further displacement of the humeral head, compared with true dislocation in which muscle pull influences the final position of the humerus. Aeknowledgements.--We are grateful to Mr. A. Dornan and Mr. F. W. Taylor for permission to pubIish details of cases under their care. They, along with Dr. R. G. Grainger, provided invaluable help and encouragement during the preparation of this paper, for which we would like to express our thanks.
THE SHOULDER JOINT--IS IT D I S L O C A T E D ? APPARENT DISLOCATION OF THE SHOULDER JOINT D. E. M A R K H A M
a n d J. R O W L A N D *
from the Department of Radiology, Royal Hospital, SheffieM The p h e n o m e n o n of apparent dislocation of the shoulder j o i n t is described a n d illustrated with reference to clinical cases. The importance of accurate clinical a n d radiological differentiation between apparent a n d true dislocation of the shoulder is emphasised, in order to prevent unnecessary a n d abortive attempts at m a n i p u l a t i o n of apparently dislocated shoulders. A regime of conservative t r e a t m e n t of apparent dislocation is outlined. The various factors believed to contribute to apparent dislocation are discussed. The three m a i n causes are T r a u m a , Infection a n d Paralysis.
INTRODUCTION A condition which presents several of the clinical and radiological features of dislocation of the shoulder has been observed, b u t some of the criteria of true dislocation are absent. Although the condition is well k n o w n to experienced orthopaedic surgeons a n d radiologists, patients with this c o n d i t i o n are often m a n i p u l a t e d by inexperienced persons in the mistaken belief that true dislocation of the j o i n t is present. T w o cases in the present series were, i n fact, mistakenly m a n i p u lated. Only after these m a n i p u l a t i o n s h a d failed to produce either clinical or radiological i m p r o v e m e n t was it recognised that these patients did n o t have a true dislocation, b u t that a c o n d i t i o n of apparent dislocation was present. Since then, several cases with apparent dislocation have been recognised a n d have been successfully treated without m a n i p u l a tion. A selection of these patients are described a n d illnstrated below. CASE HISTORIES Case 1.--D.M., a 70 year-old woman was first seen on 17.11.66 one day after a fall in which she injured her left shoulder. Clinical examination showed all movements of the left shoulder to be limited, with swelling anterior to the joint. Radiographs showed a fracture with apparent dislocation of the shoulder joint (Fig. 1). After manipulation had been undertaken by the Casualty staff under general anaesthetic, radiographs showed no apparent change in position, though symptomatically the shoulder had improved when it was supported in a sling. On clinical re-examination on 18.11.66
it was considered that the shoulder was not dislocated. Aspiration of the joint yielded 15 ml. of blood. A radiograph with the patient supporting the injured shoulder showed that there was no dislocation (Fig. 2). The position 6 weeks after aspiration is shown in Fig. 3. Case 2.--V.O'H,, a 55 year-old woman fell on 10.10.65 and sustained a fracture of the neck of the humerus with apparent dislocation of the right shoulder (Fig. 4), After manipulation by a casualty officer, a radiograph of the shoulder showed no change in the apparent dislocation. The patient's general condition was poor. She had chronic bronchitis and emphysema, together with considerable pulmonary fibrosis from long-standingtuberculosis. No further active treatment was given to the injured joint. A portable radiograph on 25.11.65 showed the right shoulder joint to be reduced. Respiratory and circulatory failure supervened and the patient died on28.11.65. Case 3.--K.H., a 20 year-old female warehouse worker presented with a three week history of a painful, swollen left shoulder. There was no history of injury. On examination the patient was pyrexial and had a tachycardia. There was an effusion into the left shoulder joint, all movements of which were grossly limited. The joint was tender to palpation and the overlying skin was red and hot. A radiograph showed subluxation of the joint. The humeral head was below its normal position with consequent loss of parallelism between it and the glenoid (Fig. 5). Aspiration of the joint was performed and 20 ml. of pus removed. This aspiration resulted in clinical and radiographic improvement in the shoulder (Fig. 6). The left arm was supported in a sling and systemic antibiotics administered. The aspirate yielded a growth of Staph. Pyogenes on culture. Subsequent progress was uneventful. The subluxation did not recur. Full movements of the joint were regained within six weeks of her initial presentation. Case 4.--R.M., a 54 year-old housewife was known to be suffering from carcinoma of the bronchus with metastases
* Present address: Department Radiology, Clayton Hospital, Wakefield. 61
62
CLINICAL
RADIOLOGY
FIG. 1 FIG. 2 FIG. 1.--Case 1. Left Shoulder: Fracture of the neck of the humerus with avulsion of the greater tuberosity and apparent dislocation of the shoulder. Fie. 2.--Case 1. Left Shoulder: After aspiration of 15 mls. of blood-stained fluid the humeral head is more closely related to the glenoid fossa.
FIG. 3 FIG. 4 FIG. 3.--Case 1. Left Shoulder: Final position of the shoulder joint 6 weeks after the aspiration. FIG. 4.--Case 2. Right Shoulder: Fracture of the neck of the humerus with apparent dislocation of the shoulder joint.
in the bodies of the fifth and sixth cervical vertebrae. T h e - o f t h e cervical spine s h o w e d collapse o f the bodies o f C.5 and C.6. (Fig. 7). patient was referred on account of paraesthesiae a n d proW h e n seen six weeks later, the weakness of the muscles gressive weakness in t h e right a r m a n d h a n d . of the right shoulder h a d progressed to complete paralysis E x a m i n a t i o n showed gross i m p a i r m e n t of m o v e m e n t o f the shoulder as a result o f muscle weakness. There was a a n d t h e joint showed clinical evidence o f apparent disfull r a n g e o f passive m o v e m e n t . T e n d o n reflexes in the right location. This was confirmed by radiographs o f the shoulder (Fig. 8). T h e a p p a r e n t dislocation was " r e d u c e d " by the a r m were diminished a n d there was diminished~sensation in simple m e a s u r e o f s u p p o r t i n g the right a r m in a sling, the C.5 a n d C_6 d e r m a t o m e s . T h e r e was at this time n o T h e patient died f r o m carcinomatosis soon after her clinical evidence o f dislocation o f the right shoulder a n d radiographs o f the joint showed no abnormality. R a d i o g r a p h s second attendance.
THE SHOULDER
JOINT--IS
FIG. 5
63
IT D I S L O C A T E D . 9
FIG. 6
FI~, 5.--Case 3. Left Shoulder: Subluxation of the shoulder joint. Fro. 6.--Case 3. Left Shoulder: Position after aspiration of 20 ml. of pus.
FIG. 7
DISCUSSION True dislocation of the shoulder joint is an easily recognised and familiar syndrome giving classical clinical and radiographic findings. However, because the recognition of apparent dislocation depends so critically upon the appreciation' of all
the clinical and radiological signs of true dislocation, and thus the absence of s o m e in apparent dislocation, the criteria of true dislocation are included in tke text. There is usually a history of injury to, or in the vicinity of, the shoulder joint, and the patient
64
CLINICAL RADIOLOGY
complains of pain in, and limitation of movement of, the joint. Clinical examination reveals an alteration in the contour of the joint compared with the normal one. The affected arm is held away from the side and the patient is unable to bring the arm into contact with the trunk. There is no movement at the joint; only scapular movement remains. The affected arm appears longer than the normal side. On radiological examination, the humeral head is displaced medially and downwards, n o r m a l l y taking up a position antero-inferior to the coracoid process of the scapula (anterior sub-coracoid dislocation). Occasionally the humeral head is displaced downwards, medially and backwards, but such posterior dislocations are rare. The clinical syndrome of apparent dislocation differs in several respects from that of true dislocation. There is usually, but by no means always, a history of trauma (c.f. Cases 3 and 4). The patient complains of pain but this is rarely as severe as in true dislocation. Although there is apparent lengthening of the affected arm, coupled with an alteration of the normal contour of the shoulder joint, the arm can be brought into contact with the trunk and movement is possible at the shoulder but is restricted in all ,directions. There are significant differences in the radiographic appearances. In apparent dislocation the shoulder joint is dislocated in so far as contact between humerus and scapula is lacking. However, the humeral head takes up a position immediately below the glenoid, there being no significant anterior, posterior or medial displacement. There is always a considerable effusion into the shoulder joint. Thus, apparent rather than true dislocation exists if, on clinical examination, the arm on the affected side can be brought into contact with the trunk and some. movement is present at the shoulder, and if a radiograph shows no significant displacement of humeral head relative to the glenoid other than in a downward direction. The causes of apparent dislocation can be grouped into three; Trauma, Infection and Paralysis. Trauma is the most common cause of apparent dislocation and is usually found with an associated comminuted fracture of the surgical neck of the humerus. In this series the patients suffering from traumatic apparent dislocation have either been of advancing years or in a debilitated general condition from other causes. The three factors which appear to contribute to the production of apparent dislocation following trauma are poor muscle tone, the presence of a tense haemarthrosis and the absence of
any significant tear in the joint capsule. The latter factor has a two-fold action, namely, to contain the humeral head within the confines of the joint and also to distend and accommodate a tense haemarthrosis. It is well known that muscle tone is diminished in those muscles adjacent to a joint which contains any type of effusion. Coupled with a pre-existing general lack of muscle tone, as found in aged or debilitated patients, the general effect is to reduce muscle spasm and thus prevent any medial pull of the displaced humeral head. The downward displacement of the humeral head occurs under the influence of gravity, facilitated by capsular distension and unopposed by muscle tone. It is believed that the pressure of adequate muscle tone in young, fit persons is sufficient to oppose the pull of gravity and accounts for the fact that traumatic apparent dislocation has not been encountered in that category of patient. The importance of these three contributory factors is emphasised by the demonstration of reduction of apparent dislocation by joint aspiration and support of the affected arm in a sling. Pyogenic arthritis is always accompanied by joint effusion. This has exactly the same effect on the capsule of the shoulder as referred to in traumatic haemarthrosis. It Mso has the effect, as in other joints similarly affected, of causing diminution in muscle mass and tone. The mechanism of apparent dislocation is, therefore, basically the same as in that due to trauma. The normal stability of the shoulder joint is largely due to the tone of its surrounding muscles. The capsule of the joint is lax, thus allowing a wide range of movement. It is, thus, easily appreciated that complete absence of muscle torte leads t o instability in the joint. In a case such as that described (Case 4) where paralysis is due to spinal cord or nerve root damage, there is also a diminution in joint proprioception. The effect of gravity is thus unopposed, and subluxation or apparent dislocation ensues. However, in the absence of capsular tear, the head of the humerus is still contained within the joint. Paralysis of the surrounding muscles prevents any further displacement of the humeral head, compared with true dislocation in which muscle pull influences the final position of the humerus. Aeknowledgements.--We are grateful to Mr. A. Dornan and Mr. F. W. Taylor for permission to pubIish details of cases under their care. They, along with Dr. R. G. Grainger, provided invaluable help and encouragement during the preparation of this paper, for which we would like to express our thanks.