Treatment of Traumatic Dislocations.

Last updated Thursday, February 10, 2005

Figure 2 - Cummerbund "handshake" cast

Posterior dislocations

Reduction

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.

If gentle closed reduction of a locked posterior glenohumeral dislocation is not possible, open reduction may be accomplished through an anterior deltopectoral approach. (See references: Doege, 1929; Hawkins, Neer, Pianta et al, 1987; Johnson, 1931; Kuhnen and Groves, 1979; Lam, 1966; McLaughlin, 1963b; Romanes, 1972; Saxena and Stavas, 1983) Because local anatomy is significantly distorted, the tendon of the long head of the biceps is used as a guide to the lesser tuberosity. The subscapularis is released either by lesser tuberosity osteotomy or by direct incision. With the glenoid thus exposed, open reduction is carried out by gently pulling the humeral head laterally and then lifting its articular surface up on the face of the glenoid.

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.

Disclaimer

This resource has been provided by the University of Washington Department of Orthopaedics and Sports Medicine as general information only. This information may not apply to a specific patient. Additional information may be found at http://www.orthop.washington.edu or by contacting the UW Department of Orthopaedics and Sports Medicine.

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