Reduction of the posterior dislocation An orthopedic surgeon should be consulted before any reduction attempt if a periarticular fracture is present or neurovascular compromise is suspected. Certain fracture-dislocation patterns, such as fractures involving the surgical neck of the humerus, usually require surgical reduction.11 Fracture-dislocations involving the greater or lesser tuberosity or the humeral shaft may be reduced by closed methods with adequate analgesia or sedation. Intra-articular local anesthetics can be very effective in providing pain relief during a reduction attempt.
Reduction of a posterior shoulder dislocation can be accomplished by traction-counter-traction using a three-step sequence. Posterior traction allows disengagement of the humeral head from the posterior glenoid rim; lateral traction places the humeral head in position; and external rotation brings the articular surface of the humeral head onto the glenoid face. Application of an anteriorly directed force over the humeral head may be necessary to reduce the dislocation once full lateral traction and maximum external rotation is accomplished. Note that the reduction of the subacute posteriorly dislocated shoulder is neither as apparent nor as dramatic as in an anterior dislocation and may necessitate close attention while performing the reduction.
Once reduced, the shoulder is immobilized in abduction with slight external rotation using a gunslinger brace or abduction pillow and sling. Adequate postreduction radiographs should be obtained, and a thorough neurologic and vascular examination should be conducted.
CONCLUSION
Diagnosing the rare posterior shoulder dislocation requires a high index of suspicion, an appreciation of subtle physical findings, and appropriate radiographic assessment, which requires two orthogonal views of the glenohumeral joint. This requirement is critical in evaluation of the shoulder and is often overlooked because of an inability to properly position the patient. Special radiographic views are available to evaluate the shoulder and will aid in the timely assessment of a posterior dislocation and prevent the morbidity associated with a missed or delayed diagnosis. JAAPA
The views expressed in this article are those of the authors and do not reflect the official policy or position of the Department of the Army, Department of Defense, or the United States government.
Christopher Furbee is a Fellow in the US Army/Baylor College of Medicine Orthopaedic PA Program at Brooke Army Medical Center, San Antonio, Texas. David Brown is Chief, Department of Orthopaedics, Brooke Army Medical Center. The authors have indicated no relationships to disclose relating to the content of this article.
REFERENCES
1. Cross J, Botero H, Brown DA. A new reduction sequence for the locked posterior shoulder dislocation. Case report and review of the literature. Society of Military Orthopoedic Surgeons 2008 annual meeting. Abstract #33. http://www.somos.org/associations/10068/files/abstracts_2008.pdf. Accessed November 10, 2009.
2. Hawkins RJ, Neer CS, Pianta RM, Mendoza FX. Locked posterior dislocation of the shoulder. J Bone Joint Surg Am. 1987;69(1):9-18.
3. McLaughlin HL. Posterior dislocation of the shoulder. J Bone Joint Surg Am. 1952;34:584-590.
4. Neer CS II. Displaced proximal humeral fractures: I. Classification and evaluation. J Bone Joint Surg Am. 1970;52(6):1077-1089.
5. Nobel W. Posterior traumatic dislocation of the shoulder. J Bone Joint Surg Am. 1962;44:523-538.
6. Rowe CR, Zarins B. Chronic unreduced dislocations of the shoulder. J Bone Joint Surg Am. 1982;64(4):494-505.
7. Robinson CM, Aderinto J. Posterior shoulder dislocations and fracture-dislocations. J Bone Joint Surg Am. 2005;87(3):639-650.
8. Shaw JL. Bilateral posterior fracture-dislocation of the shoulder and other trauma caused by convulsive seizures. J Bone Joint Surg Am. 1971;53(7):1437-1440.
9. Cisternino SJ, Rogers LF, Stufflebam BC, Kruglik GD. The trough line: a radiographic sign of posterior shoulder dislocation. Am J Roentgenol. 1978;130(5):951-954.
10. Bloom MH, Obata WG. Diagnosis of posterior dislocation of the shoulder with use of Velpeau axillary and angle-up roentgenographic views. J Bone Joint Surg Am. 1967;49(5):943-949.
11. DeWall M, Lervick G, Marsh JL. Posterior fracture-dislocation of the proximal humerus: treatment by closed reduction and limited fixation; a report of four cases. J Orthop Trauma. 2005;19(1):48-51.