Injuries Associated with Anterior Dislocations

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Injuries Associated with Anterior Dislocations
Last Updated: Monday, February 4, 2013

A common feature of traumatic anterior dislocations is avulsion of the anterior-inferior glenohumeral ligaments and capsule from the glenoid lip especially in younger individuals.

Non-healing avulsion

Non-healing of this avulsion is a major factor in recurrent traumatic instability. Occasionally the capsule may be avulsed from the anteroinferior humerus sometimes with a fleck of bone (see figures 1 2 and 3).

 

 

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Figure 1

 

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Figure 2

 

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Figure 3

 

Types of fractures

Fractures of the glenoid (see figure 4) humeral head and tuberosities (see figure 5) may accompany traumatic dislocations. A CT scan may be helpful in determining the degree of posterior displacement of fractures.

It is important to seek evidence of a non-displaced humeral neck fracture on the pre-reduction radiographs lest this fracture be displaced during attempted closed reduction. (Ferkel et al 1984)

Other fractures such as of the coracoid process may be associated with glenohumeral dislocations. (Benechetrit and Friedman 1979; Wong-Pack et al 1980)

 

 

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Figure 4

 

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Figure 5

 

Rotator cuff tears

Rotator cuff tears may accompany anterior and inferior glenohumeral dislocations (see figure 6). The frequency of this complication increases with age: in patients over 40 years of age the incidence exceeds 30 per cent; over age 60 it exceeds 80 per cent. (Itoi and Tabata 1992; Pasila et al 1978; Pettersson 1942; Reeves 1969; Sonnabend 1994; Symeonides 1972; Tijmes et al 1979)

Rotator cuff tears may present as pain or weakness on external rotation and abduction. (Hawkins et al 1984; Neviaser 1988; Pettersson 1942; Reeves 1968a; White 1976) Sonnabend reported a series of primary shoulder dislocations in patients older than 40 years of age. (Sonnabend 1994) Of the 13 patients who had complaints of weakness or pain after 3 weeks eleven had rotator cuff tears. However the presence of a rotator cuff tear may be masked by a coexisting axillary nerve palsy. (Gonzalez and Lopez 1991; Johnson and Bayley 1981)

Shoulder ultrasonography (Mack et al 1985) arthrography or magnetic resonance imaging is considered to evaluate the possibility of an associated cuff tear when:

 

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Figure 6

  1. shoulder dislocations occur in patients over 40 years of age
  2. there has been substantial initial displacement of the humeral head (such as in a subglenoid dislocation) and
  3. there is persistent pain or loss of rotator cuff strength three weeks after a glenohumeral dislocation.

Toolanen found sonographic evidence of rotator cuff lesions in 24 of 63 patients over the age of 40 years at the time of anterior glenohumeral dislocation. (Toolanen et al 1993)

Prompt operative repair of these acute cuff tears is usually indicated. Itoi and Tabata (Itoi and Tabata 1992) reported 16 rotator cuff tears in 109 shoulders with a traumatic anterior dislocation. The cuff was surgically repaired in 11 shoulders and the results were graded as satisfactory in 73% of cases.

Neviaser et al (Neviaser et al 1993) reported on thirty-seven patients older than 40 years of age in whom the diagnosis of cuff rupture was initially missed after an anterior dislocation of the shoulder. The weakness from the cuff rupture was often erroneously attributed to axillary neuropathy. Eleven of these patients developed recurrent anterior instability that was due to rupture of the subscapularis and anterior capsule from the lesser tuberosity. None of these shoulders had a Bankart lesion. Repair of the capsule and subscapularis restored stability in all of the patients with recurrence.

 

Vascular damage most frequently occurs in elderly patients with stiffer more fragile vessels.

Anatomical locations

The injury may be to the axillary artery or vein or to the branches of the axillary artery--the thoracoacromial subscapular circumflex and rarely the long thoracic. Sometimes these injuries can be combined as pointed out by Kirker who described a case of rupture of the axillary artery and axillary vein along with a brachial plexus palsy. ( Kirker 1952) Injury may occur at the time of either dislocation or reduction. (Antal et al 1973; Curr 1970; Gugenheim and Sanders 1984; Jardon et al 1973)

Anatomy

The axillary artery is divided into three parts that lie medial to behind and lateral to the pectoralis minor muscle. Injuries most commonly involve the second part where the thoracoacromial trunk may be avulsed and the third part where the subscapular and circumflex branches may be avulsed or the axillary artery may be totally ruptured.

Mechanism of injury

Damage to the axillary artery can take the form of a complete transection a linear tear of the artery caused by avulsion of one of its branches or an intravascular thrombus perhaps related to an intimal tear. The artery is relatively fixed at the lateral margin of the pectoralis minor muscle. With abduction and external rotation the artery is taut; when the head dislocates it forces the axillary artery forward and the pectoralis minor acts as a fulcrum over which the artery is deformed and ruptured. (Brown and Navigato 1968; Jardon Hood and Lynch 1973; Milton 1953-1955)

Watson-Jones (Watson-Jones 1957) reported the case of a man who had multiple anterior dislocations that he reduced himself. Finally when the man was older the axillary artery ruptured during one of the dislocations and he died. Vascular injuries may occur either at the time of dislocation or during attempted reduction. Sometimes it is unclear which is the case. (Kirker 1952; Ng et al 1990; Stener 1957)

Injury at the time of dislocation

Vascular injuries are commonly associated with inferior dislocation. (Gardham and Scott 1980; Lev-EI and Rubinstein 1981; Lynn 1921; Meadowcroft and Kain 1977) Gardham and Scott (Gardham and Scott 1980) reported an axillary artery occlusion with an erect dislocation of the shoulder in a 40-year-old patient who had fallen headfirst down an escalator. Although vascular injuries are most common in older individuals they can occur at any age. (Bertrand et al. 1981; Drury and Scullion 1980; Fitzgerald and Keates 1975; Lescher and Andersen 1979; Sarma et al 1981; Stein 1986) Banatta and coworkers (Baratta et al 1983) reported the case of a 13-year-old boy who ruptured his axillary artery with a subcoracoid dislocation sustained while wrestling.

Injury at the time of reduction

Vascular damage at the time of reduction occurs primarily in the elderly particularly when a chronic old anterior dislocation is mistaken for an acute injury and a closed reduction is attempted. The largest series of vascular complications associated with closed reduction of the shoulder has been reported by Calvet and coworkers (Calvet et al 1942) who in 1941 collected 90 cases. This paper revealing the tragic end results must have accomplished its purpose because there have been very few reports in the literature since then dealing with the complications that occur during reduction. In their series in which 64 of 91 reductions were performed many weeks after the initial dislocation the mortality rate was 50 per cent. The other patients either lost the arm or the function of the arm. Besides the long delay from dislocation to reduction these injuries may also be due to the use of excessive force. Delpeche observed a case in which the force of 10 men was used to accomplish the shoulder reduction damaging the axillary vessel. (Guibe 1911)

Signs and symptoms

Vascular damage may be obvious or subtle. Findings may include pain expanding hematoma pulse deficit peripheral cyanosis peripheral coolness and pallor neurological dysfunction and shock. A Doppler or an arteriogram should confirm the diagnosis and locate the site of injury.

Treatment and prognosis

Patients suspected of having major arterial injury are managed as a surgical emergency with the establishment of a major intravenous line and obtaining blood for transfusion. Jardon and coworkers (Jardon Hood and Lynch 1973) has pointed out that bleeding can be temporarily controlled by digital pressure on the axillary artery over the first rib. This author also recommends that the axillary artery be explored through the subclavicular operative approach as described by Steenburg and Tavitch. (Steenburg and Ravitch 1963)

The treatment of choice for a damaged axillary artery is either by direct repair or by bypass graft after resection of the injury. Excellent results have been reported with prompt management of these vascular injuries. (Brown and Navigato 1968; Cranley and Krause 1958; Dolk and Stenberg 1991; Gardham and Scott 1980; Gibson 1962; Henson 1956; Jardon Hood and Lynch 1973; Lev-EI and Rubinstein 1981; McKenzie and Sinclair 1958; Rob and Standeven 1956; Stevens 1934) The results of simple ligation of the vessels in the elderly patient have been disappointing probably because of poor collateral circulation and the presence of arteriosclerotic vascular disease in these typically older individuals. (Johnston and Lowry 1962; Kirker 1952; Van der Spek 1964) Even when ligation has been performed in younger patients with good collateral circulation approximately two-thirds of these patients have lost function of the upper extremity for example by developing upper extremity claudication.

Effect of age

The age of the patient at the time of the initial dislocation has a major influence on the incidence of redislocation. (Rowe 1956; Rowe and Sakellarides 1961) Several authors have reported that individuals under the age of twenty at the time of the initial dislocation have up to a 90% chance of having recurrent instability. (Arciero et al 1994; Henry and Genung 1982; Hovelius 1987; Hovelius et al 1994; Kiviluoto et al 1980; McLaughlin and Cavallaro 1950; McLaughlin and MacLellan 1967; Moseley 1961; Rowe 1956; Simonet and Cofield 1983; Wheeler et al 1989) Over the age of 40 the incidence drops sharply to 10 to 15 per cent. (McLaughlin and MacLellan 1967; Rowe and Sakellarides 1961) Hovelius et al(Hovelius et al 1996) reported a careful prospective study with somewhat lower incidences of recurrences in each age group: 33% under 20 25% between 20 and 30 and 10% between 30-40 years. The majority of all recurrences occur within the first two years after the first traumatic dislocation. (Adams 1948; Bankart 1939; DePalma 1973; Eyre-Brook 1943; McLaughlin and Cavallaro 1950; Moseley 1945; Moseley 1963; Rowe 1956; Rowe 1978; Townley 1950)

Effects of trauma sports gender and dominance

Rowe (Rowe 1956; Rowe and Sakellarides 1961) has pointed out that the recurrence rate varies inversely with the severity of the original trauma; in other words the more easily the dislocation occurred initially the more easily it recurs. The recurrence rate among athletes may be higher than non athletes (Simonet and Cofield 1983) and higher among men than women (Moseley 1961). Dominance of the affected shoulder does not seem to have a major effect on the recurrence rate. (Rowe and Sakellarides 1961)

Effect of post dislocation treatment

In many reports the incidence of recurrence appears to be relatively insensitive to the type (sling vs. plaster Velpeau) and duration of immobilization (0 vs. 4 weeks) of the shoulder following initial dislocation. (Ehgartner 1977; Hovelius et al 1983; McLaughlin and Cavallaro 1950; Rowe and Sakellarides 1961)

By contrast others have reported that longer periods of immobilization (over three weeks) are associated with a reduced incidence of recurrence. (Kazar and Relovszky 1969; Stromsoe et al 1980)

In a definitive 10-year prospective study Hovelius et al studied the effect of immobilization on the incidence of recurrence. (Hovelius Augustini Fredin et al 1996) After reduction 247 primary anterior dislocations were partially randomized to either a 3-4 week period of immobilization or to a sling to be discarded after comfort was achieved. The authors concluded that the immobilization did not affect the rate of recurrence. The results provide useful 'rules of thumb': overall half of these shoulders had recurrent dislocations; half of the recurrences had surgical treatment; half of the recurrences treated nonoperatively were stable without surgery at 10 years. One of six patients had dislocation of the opposite shoulder. Eleven percent of the shoulders had at least mild evidence of secondary degenerative joint disease. Interestingly this secondary DJD was observed in both surgical and nonsurgical cases.

Aronen and Regan (Aronen and Regan 1984) reported a three year average followup study on 20 primary dislocations in Navy midshipmen treated with a three month aggressive post dislocation program. The program consisted of three weeks of sling immobilization followed by progressive strengthening. The patients were not allowed to return to activity until there was no evidence of weakness or atrophy and no apprehension on abduction and external rotation. In this series there were no recurrent dislocation and two recurrent subluxations. Similarly Yoneda (Yoneda et al 1982) reported good results in 83% of patients in a program emphasizing post immobilization exercises.

The effect of fractures

The incidence of recurrence is lower when a first-time shoulder dislocation is associated with a greater tuberosity fracture. (DePalma 1950a; Hovelius 1987; Hovelius Augustini Fredin et al 1996; McLaughlin and MacLellan 1967; Roston and Haines 1947; Rowe 1956; Rowe Pierce and Clark 1973) Hovelius (Hovelius 1987) reported that these fractures were four times as common in patients over 30: 23% compared with 8% among patients under 30.

Other fractures such as substantial posterior lateral humeral head lesions and fractures of the glenoid lip are likely to be associated with an increased incidence of recurrent instability.

In conclusion it appears that the injuries sustained by young patients in association with traumatic dislocations are relatively unlikely to heal in a manner yielding a stable shoulder. Probably the most important of these unhealing injuries are:

  1. the avulsion of the glenohumeral capsular ligaments from the anterior glenoid lip and
  2. the posterolateral humeral head defect.

Older patients may tend to stretch the capsule or fracture the greater tuberosity either of which is likely to heal yielding a stable shoulder. In atraumatic instability there is no traumatic lesion and thus a high chance of recurrence. The degree of trauma and the age of the patient seem to be the most important factors in determining the recurrence rate.