Timing of reduction and analgesia

Early relocation promptly eliminates the stretch and compression of neurovascular structures, minimizes the amount of muscle spasm that must be overcome to effect reduction, and prevents progressive enlargement of the humeral head defect in locked dislocations. The extent of anesthesia required to accomplish a gentle reduction depends on many factors, including the amount of trauma that produced the dislocation, the duration of the dislocation, the number of previous dislocations, whether the dislocation is locked, and to what extent the patient can voluntarily relax the shoulder musculature. When seen acutely, some dislocations can be reduced without the use of medication. At the other extreme, reduction of a long-standing, locked dislocation may require a brachial plexus block or general anesthetic with muscle relaxation. Many practitioners use narcotics and muscle relaxants to aid in the reduction of shoulder dislocations. A potential trap exists: the dosages required to produce muscle relaxation while the shoulder is dislocated may be sufficient to produce respiratory depression once the shoulder is reduced. Our recommendation is that if these medications are to be used, they should be administered through an established intravenous line. This produces a more rapid onset, a short duration of action, and the opportunity to adjust the required dose more appropriately. Furthermore, resuscitation (if necessary) is facilitated by the prospective presence of such a route of access. Airway management tools should be readily available.

Lippitt et al (Lippitt et al, 1991; Lippitt et al, 1992) compared two methods of analgesia for the reduction of anterior dislocations: (1) intravenous analgesia and muscle relaxation and (2) intraarticular lidocaine. With respect to the first, they found a 75% success rate and a 37% complication rate in a retrospective series of 52 reductions in which intravenous narcotics (morphine (3-24 mg) or meperidine (12.5 - 100 mg) with or without diazepam (1.5 - 15 mg) or midazolam (1 - 10 mg)) were used for analgesia. They remarked on the difficulty of determining the appropriate intravenous dose of narcotics. Level of pain, age, smoking history, alcohol consumption, cardiac disease and regional perfusion are just a few of the factors which may influence the narcotic requirement (Bailey and Stanley, 1986). Older patients and intoxicated patients are more sensitive to the respiratory depressant effects of narcotics. Because pain counteracts the respiratory depressant effects, patients sedated by narcotics are at increased risk of respiratory depression after removal of the painful stimulus when the shoulder is reduced. Complications from intravenous analgesia included respiratory depression, hypotension, hyperemesis, and oversedation. With respect to the second method using 20 cc of 1% plain intraarticular lidocaine, Lippitt et al found a 100% success rate in the reduction of 40 dislocations with no complications. One patient inadvertently received 400 mg instead of 200 mg of lidocaine and developed transient tinnitus, perioral numbness, and mild dysarthria. A survey revealed that both the patients and the physicians were satisfied with this method. The authors speculated that the success of the intraarticular injection may be due to a combination of pain relief allowing reduction, relief from muscle spasm and venting of the joint.

Method of reduction

Once the shoulder is relaxed, a variety of gentle methods can be used to achieve reduction. Gentle traction on the arm is common to most. One such method is known as the Stimson technique. Although named for Lewis A. Stimson (Stimson, 1900; Stimson, 1912) of New York City, Stimson credited a Dr. Cole, a house-staff physician of the Chambers Street Hospital. In the Stimson method, the patient is placed prone on the edge of the examining table while downward traction is gently applied. (Stimson, 1900) The traction force may be applied by the weight of the arm, by weights taped to the wrist, or by the surgeon. It may take several minutes for the traction to produce muscle relaxation. It is important that patients not be left unattended in this position, particularly if narcotics and muscle relaxants have been administered.

Analgesia

While analgesia may not be necessary to achieve reduction, we are impressed with the safety and effectiveness of intraarticular lidocaine as described by Lippitt et al. (Lippitt, Kennedy and Thompson, 1991; Lippitt, Kennedy and Thompson, 1992) In this method a maximum 20 cc of 1% plain lidocaine is injected using an 18 gauge needle placed two centimeters below the lateral edge of the acromion just posterior to the dislocated humeral head and directed towards the glenoid fossa. The amount of lidocaine is limited to 200 mg. (Savarsee and Covino, 1986) Placement of the needle in the joint is confirmed by a combination of (1) feeling the needle penetrate the glenohumeral capsule, (2) aspirating joint fluid/hemarthrosis and assuring that the injection is not intravascular, (3) gently palpating the glenoid fossa with the needle, and (4) verifying easy flow on injection and return of the injected lidocaine solution. Fifteen minutes are allowed to maximize the analgesic effect of the lidocaine prior to manipulation.

Maneuver

Reduction and analgesia

The principles and methods for reducing a chronic dislocation are similar to those relating to an acute dislocation except for the fact that the patient and the shoulder are usually more fragile and the relocation is more difficult. As the chronicity of the dislocation increases, so do the difficulties and complications of reduction. When one encounters an elderly patient with pain in the shoulder whose x-rays reveal an anterior dislocation, a very careful history is needed to determine whether the initial injury occurred recently or quite a while earlier.

Chronic dislocations are seen most commonly in elderly people and in those whose general health or mental status may prevent them from seeking help for the injury. The event causing injury itself may be relatively trivial. (Bennett, 1936; Mirick, Clinton and Ruiz, 1979) Old age, chronicity of dislocation, and soft bone make closed reduction difficult and dangerous. (McLaughlin, 1949) If a closed reduction is to be performed, it should be done with minimal traction, without leverage, and with total muscle relaxation under controlled general anesthesia. If the dislocation is over a week old, the humeral head is likely to be firmly impaled on the anterior glenoid with such soft tissue contraction that gentle closed reduction is impossible.

Open reduction

If a gentle attempt at closed reduction fails, open procedure reduction is considered. This can be a complex procedure because of the altered position of the axillary artery and branches of the brachial plexus and because the structures are tight and scarred. When the risks of attempting reduction appear to outweigh the advantages, the dislocated position may be accepted. Sometimes the symptoms of chronic dislocation are surprisingly minimal. (Ganel et al, 1980)

In performing an open reduction, the subscapularis and anterior capsule are incised near their insertion to the lesser tuberosity allowing substantial external rotation of the dislocated shoulder. External rotation and lateral traction will usually disimpact the humerus from the glenoid. While lateral traction is maintained, the humerus is gently internally rotated under direct vision to assure that the articular surface of the humerus passes safely by the anterior glenoid lip and into the glenoid fossa. Leverage is avoided because the head is usually very soft. If the posterolateral head defect is greater than 40 per cent or if the head collapses during reduction, a humeral head prosthesis may be necessary to restore a functional joint surface. The subscapularis and capsule are then repaired. The shoulder is carefully inspected for evidence of cuff tear or vascular damage.

Results of treatment of chronic dislocations

Schulz and associates (Schulz et al, 1969) reported a series of 17 posterior and 44 anterior chronic dislocations. These dislocations occurred primarily among elderly people; more than half of the dislocations were associated with fracture of the tuberosities, humeral head, humeral neck, glenoid, or coracoid process. More than one third involved neurological deficits. Closed reduction was attempted in 40 shoulders and was successful in twenty. Of the twenty shoulders successfully reduced (3 posterior and 17 anterior), the duration of dislocation exceeded four weeks in only one instance. Open reduction was performed in 20 and humeral head excision in 6. Eight patients were not treated, and five shoulders were irreducible.

Perniceni and coworkers (Perniceni and Augereau, 1983) described the reinforcement of the anterior shoulder complex in three patients after reduction of neglected anterior dislocations of the shoulder. They used the Gosset (Gosset, 1960) technique, which places a rib graft between the coracoid and the glenoid rim. Rowe and Zarins (Rowe and Zarins, 1982) reported on 24 patients with unreduced dislocations of the shoulder and operated on 14 of them.

After reducing the dislocation, anteroposterior and lateral x-ray views are obtained in the plane of the scapula to verify the adequacy of the reduction and to provide an additional opportunity to detect fractures of the glenoid and proximal humerus. The patient's neurological status is again checked, including the sensory and motor functions of all five major nerves in the upper extremity. The strength of the pulse is verified and evidence of bruits or an expanding hematoma is sought. (Gugenheim and Sanders, 1984) The integrity of the rotator cuff is initially evaluated by observing the strength of isometric external rotation and abduction.

Trimmings (Trimmings, 1985) demonstrated that aspiration of the hemarthrosis from the shoulder can be an effective means of reducing discomfort after the shoulder is reduced.

Protection

Since recurrent glenohumeral instability is the most common complication of a glenohumeral dislocation, postreduction treatment focuses on optimizing shoulder stability. Thus, two potentially important elements in postreduction treatment are protection and muscle rehabilitation. Reeves demonstrated that after repair of the subscapularis in primates, three months were necessary before normal capsular patterns of collagen bundles were observed, five months before the tendon was histologically normal, and four to five months before tensile strength was regained. (Reeves, 1968b) It is unknown whether labral tears or ligamentous avulsions from the glenoid heal or how long this might take. In any event, it is apparent that the shoulder cannot be immobilized for the full length of time required for complete healing. (The reader is referred to the previous section "Recurrence of instability after anterior dislocations, effect of post dislocation treatment" for a review of some of the literature on the effectiveness of different post-reduction management programs.)

The authors treat first time dislocations in a manner similar to the post operative management for dislocation repairs. Thus younger patients are placed on the "90-0 program" in which flexion is limited to 90 degrees and external rotation is limited to zero degrees for the first three weeks while strength is maintained with cuff and deltoid isometrics. The elbow is fully extended at least several times a day to prevent "sling soreness." Because persons over 30 are more likely to develop stiffness of the shoulder, elbow, and hand, the duration of immobilization is progressively reduced for individuals of increasing age. (Kiviluoto, Pasila, Jaroma et al, 1980; McLaughlin and Cavallaro, 1950; McLaughlin and MacLellan, 1967; Rowe, 1956; Yoneda, Welsh and MacIntosh, 1982) Patients are checked at three weeks after relocation and examined for stiffness; if external rotation to zero degrees is difficult, formal stretching exercises are started. Otherwise, the patient is allowed to increase the use of the shoulder as comfort permits.

Strengthening

At three weeks, the patient institutes more vigorous rotator cuff strengthening exercises using rubber tubing or weights. The patient is informed that strong subscapularis and infraspinatus muscles are ideally situated to increase glenohumeral stability. (Saha, 1971)

Burkhead and Rockwood, (Burkhead and Rockwood, 1992) Glousman and coworkers, (Glousman, Jobe and Tibone, 1988) and Tibone and Bradley (Tibone and Bradley, 1993) have emphasized the importance of strengthening not only the rotator cuff but also the scapular stabilizing muscles because of their vital importance in providing a stable platform for shoulder function. Even in the case of recurrent instability, Rockwood and Burkhead (Burkhead and Rockwood, 1992) found that a complete exercise program was effective in the management of 12% of patients with traumatic subluxation, 80% with anterior atraumatic subluxation, and 90% with posterior instability.

Swimming is recommended at six weeks to enhance endurance and coordination. By three months after the dislocation, most patients should have almost full flexion and rotation of the shoulder. The patient is not allowed to use the injured arm in sports or for over-the-head labor until they have achieved (1) normal rotator strength, (2) comfortable and nearly full forward elevation, and (3) confidence in their shoulder with it in the necessary positions. Any deviation from the expected course of recovery requires careful re-evaluation for occult fractures, loose bodies, rotator cuff tears, peripheral nerve injuries, and glenohumeral arthritis.

Tietjen (Tietjen, 1982) reported a case in which surgery was required to retrieve the avulsed supraspinatus, infraspinatus, and teres minor from their interposition between the humeral head and the glenoid.

Bridle and Ferris (Bridle and Ferris, 1990) reported a case of apparent successful closed reduction of an anterior shoulder dislocation that appeared to be confirmed on an anteroposterior radiograph. However, the patient continued to experience severe pain and a subsequent axillary lateral view demonstrated a persistent anterior subluxation of the glenohumeral joint. At the time of open reduction the ruptured muscle belly of the subscapularis was found interposed between the humeral head and glenoid. Inao and associates (Inao et al, 1990) reported a case of an acute anterior shoulder dislocation that was irreducible by closed treatment due to the interposition of the posteriorly displaced tendon of the long head of the biceps.

Displaced fracture of the greater tuberosity

Although fractures of the greater tuberosity are not uncommonly associated with anterior shoulder dislocation, the tuberosity usually reduces into an acceptable position when the shoulder is reduced (see figure 1). Occasionally the greater tuberosity fragment displaces up under the acromion process or is pulled posteriorly by the cuff muscles. If the greater tuberosity remains displaced following reduction of the shoulder joint, consideration should be given to anatomical reduction and internal fixation of the fragment and repair of the attendant split in the tendons of the rotator cuff. It is relatively easy to determine the amount of superior displacement of the tuberosity fragment on the anteroposterior roentgenogram in the plane of the scapula. Posterior displacement can be more difficult to discern. It is important to look for the "vacant tuberosity" sign, wherein the normal contour of the greater tuberosity is lacking. If there is concern about the anteroposterior position of the tuberosity on plain films, a CT scan should be considered. If the tuberosity is allowed to heal with posterior displacement, it may produce both the functional equivalent of a rotator cuff tear and a bony block to external rotation.

Special problems

The reduction of acute, traumatic posterior dislocations may be much more difficult than the reduction of acute, traumatic anterior dislocations. Hawkins and coworkers (Hawkins, Neer, Pianta et al, 1987) reviewed 41 cases of locked posterior shoulder dislocations. The average interval between injury and diagnosis was one year! In seven shoulders the deformity was accepted. Closed reduction was successful in only 6 of the 12 cases in which it was attempted.

Intravenous narcotics combined with muscle relaxants or tranquilizers may provide insufficient analgesia and muscle relaxation; general anesthesia with muscle paralysis may be required. Atraumatic closed reduction can usually be accomplished once the muscle spasm has been eliminated. With the patient in the supine position, longitudinal and lateral traction is applied to the arm while it is gently rocked in internal and external rotation. Once the head is disimpacted it is lifted anteriorly back into the glenoid fossa. In locked posterior dislocations, it may be necessary to gently stretch out the posterior cuff and capsule by maximally internally rotating the humerus before reduction is attempted. Care should be taken not to force the arm into external rotation before reduction is achieved; if the head is locked posteriorly on the glenoid rim, forced external rotation could produce a fracture of the head or shaft of the humerus.

Postreduction care

If, after closed reduction, the shoulder is stable in the sling position, this type of post reduction management is most convenient for the patient. However, if there is concern about recurrent instability, the shoulder is immobilized in a shoulder spica or brace with the amount of external rotation necessary to provide stability. (Cautilli et al, 1978a; Cautilli et al, 1978b) Scougall (Scougall, 1957) has shown experimentally in monkeys that a surgically detached posterior glenoid labrum and capsule heal soundly without repair. He concluded that the best position of immobilization, to allow healing for all of the posterior structures, was in abduction, external rotation, and extension and that the position should be maintained for four weeks.

While some have recommended pin fixation for three weeks after reduction (Wilson and McKeever, 1949), this method carries risk of pin breakage and infection.

Early surgery in acute traumatic posterior dislocation

Indications for surgery include a displaced lesser tuberosity fracture, a significant posterior glenoid fracture, an irreducible dislocation, an open dislocation, or an unstable reduction.

A major cause of recurrent instability after reduction of a posterior dislocation is the presence of a large anteromedial humeral head defect. If at the time of reduction, stability cannot be obtained because of such a defect, it may be rendered extra-articular by filling it with the subscapularis tendon as described by McLaughlin (Lev-EI and Rubinstein, 1981; McLaughlin, 1951; McLaughlin, 1952; McLaughlin, 1959; McLaughlin, 1963b) or the lesser tuberosity as described by Neer. (Nicola, 1953, Rockwood, 1984) If the humeral head defect involves over 30 per cent of the articular surface, prosthetic replacement may be indicated, otherwise instability may recur with internal rotation. Hawkins et al demonstrated the use of each of these techniques in a series of locked posterior dislocations. (Hawkins, Neer, Pianta et al, 1987).

After surgery the arm may be immobilized in a sling and swathe for two weeks as recommended by McLaughlin, positioning the arm at the side posterior to the coronal plane using a strip of tape or canvas restraint as recommended by Rowe and Zarins (Rowe and Zarins, 1982), or a modified spica in neutral rotation for six weeks followed by an additional 3 to 6 months of rehabilitative exercises as recommended by Rockwood. (Rockwood, 1984)

Keppler et al have suggested using rotational osteotomy of the humerus in the post reduction management of locked posterior dislocations. (Keppler et al, 1994).

Chronic posterior dislocation

Preferred method of treatment

Our management of acute traumatic posterior dislocations begins with a definition of the extent and chronicity of the injury. A complete radiographic evaluation is necessary, including anteroposterior and lateral views in the plane of the scapula and an axillary view. Careful note is made of associated fractures, including the extent of the impression fracture of the anteromedial humeral head. Under anesthesia and muscle relaxation, a gentle closed reduction is attempted using axial traction on the arm. If the head is locked on the glenoid rim, gentle internal rotation may stretch out the posterior capsule to facilitate reduction. Lateral traction on the proximal humerus may unlock the humeral head. Once it is unlocked, the humerus is gently externally rotated. After reduction is achieved and confirmed by postreduction radiographs, the reduction is maintained for three weeks by a cummerbund "handshake" cast or orthotic (see figure) in neutral rotation and slight extension. External rotation and deltoid isometrics are carried out during this period of immobilization. After removal of the cast, a vigorous internal and external rotator strengthening program is initiated. Range of motion is allowed to return with active use, beginning with elevation in the plane of the scapula. Vigorous physical activities are not resumed until the shoulder is strong and three months have elapsed since reduction. Swimming is encouraged to develop endurance and muscle coordination.

When there is a humeral head defect comprising 20-40% of the humeral head, a subscapularis transfer into the defect is considered to prevent recurrent instability. When the humeral head defect is greater than 40%, a proximal humeral prosthesis is considered to replace the lost articular surface. When the dislocation is obviously chronic, consideration can be given to accepting the dislocation and focusing on enhancing the patient's ability to carry out activities of daily living.