Commentary & Perspective on
"Redislocation of the Shoulder During the First Six Weeks After a Primary Anterior Dislocation: Risk Factors and Results of Treatment"
by C.M. Robinson, BMed Sci, FRCS(Ed)Orth, et al.

Commentary & Perspective by
Richard J. Hawkins, MD*, and Thomas A. Joseph, MD*,
Steadman Hawkins Clinic, Vail, CO

The shoulder is the most frequently dislocated major joint. Following an initial closed reduction, some injuries heal uneventfully while others become the source of recurrent dislocations and morbidity. The authors of several studies have sought to identify risk factors for recurrence to provide a basis for better counsel and management of these patients. It is generally accepted that recurrence becomes less frequent with age and that the particular pathology resulting from a dislocation is also a function of age. In younger patients, the hallmark finding is capsulolabral detachment from the anteroinferior aspect of the glenoid rim, whereas in patients beyond the age of forty, rotator cuff tears predominate.

This prospective cohort study by Robinson et al. is well designed and attempts to answer the very specific question: "Which patients are at risk for early recurrence during the first six weeks after a primary anterior dislocation of the shoulder?" Of 538 patients that were followed, seventeen (3.2%) sustained a redislocation within the first week after the original injury. Fifteen of the seventeen patients were treated operatively and had satisfactory short-term outcomes. Only one patient experienced recurrent instability. Appropriate functional assessment instruments (the rating system of Constant and Murley, the Disabilities of the Arm, Shoulder, and Hand Questionnaire [DASH], and the Short Form-36 Health Survey [SF-36]) were used. There is no mention, however, of outcomes in the remaining 521 patients or whether redislocation occurred later than six weeks after the primary dislocation. This additional information is of equal importance in terms of identifying other subgroups and their patterns of reinjury.

It is important to recognize that the authors have identified a very small subset of unstable shoulder injuries that represent 3.2% of the total number of dislocations in their series. Our experience confirms that of Robinson et al.: early redislocations within the first week, especially those that occur despite immobilization in a sling, usually appear in the setting of high-energy injuries with extensive soft-tissue disruption or associated fracture(s). Practically speaking, however, most patients with a first-time dislocation do not have a recurrence until symptoms have subsided and normal activity is resumed. For the young and active population, this often coincides with a return to athletic participation. By virtue of their inclusion period, Robinson et al. have thus selected out a subset of predominantly older individuals with high-energy injuries.

The authors used calculations of relative risk to identify risk factors for early recurrence. These include: fractures of the glenoid rim with or without fracture of the greater tuberosity of the humerus, high-energy injuries, large rotator cuff tears, and neurologic injury. Of the seventeen patients who sustained an early redislocation, fourteen were over the age of forty and eight of those were over the age of sixty. Although recurrent instability is much less common in these age groups, the incidence of rotator cuff tear is quite high, ranging from 34% to 100%^1-4. The findings of Robinson et al. reinforce the need to examine older patients carefully for evidence of rotator cuff tear following shoulder dislocation. Sonnabend outlined an algorithm for treating primary traumatic dislocations in patients over the age of forty⁴. We have successfully used a similar algorithm. Robinson et al. have introduced an additional variable, that of early recurrence despite immobilization, and have shown that good results can be achieved when this complication is identified and treated operatively on the basis of the underlying pathoanatomy. In all patients who had large or massive rotator cuff tears, repair was possible and stability was achieved. Theoretically, delays in the recognition and treatment of redislocation may result in chronic dislocation or irreparable rotator cuff pathology.

*The authors did not receive grants or outside funding in support of their research or preparation of this manuscript. They did not receive payments or other benefits or a commitment or agreement to provide such benefits from a commercial entity. A commercial entity (Aircast, Inc.; EBI Medical Systems; HealthONE Alliance; Innovation Sports; Nippon SIGMAX Co. Ltd.; Ormed; Peak Performance Tech, Inc.; Pfizer, Inc.; Smith & Nephew, Inc.; Sulzer Orthopedics Ltd.; Vail Resorts; and Vail Valley Medical Center) paid or directed, or agreed to pay or direct, benefits to a research fund, foundation, educational institution, or other charitable or nonprofit organization with which the authors are affiliated or associated. R.J.H. also receives royalties and consultant fees from Surgical Dynamics, and royalties from Hardcore Books and Depuy.

References

1. Gumina S, Postacchini F. Anterior dislocation of the shoulder in elderly patients. J Bone Joint Surg Br. 1997;79:540-3.
2. Hawkins RJ, Bell RH, Hawkins RH, Koppert GJ. Anterior dislocation of the shoulder in the older patient. Clin Orthop. 1986;206:192-5.
3. Neviaser RJ, Neviaser TJ, Neviaser JS. Anterior dislocation of the shoulder and rotator cuff rupture. Clin Orthop. 1993;291:103-6.
4. Sonnabend DH. Treatment of primary anterior shoulder dislocation in patients older than 40 years of age. Conservative versus operative. Clin Orthop. 1994;304:74-7.