Posterior-inferior capsular shift for the treatment of recurrent, voluntary posterior subluxation of the shoulder

Background: The treatment of recurrent posterior instability of the shoulde r, especially when it is associated with voluntary subluxation, remains con troversial, and operative correction generally is not advised. Methods: The results of operative correction of recurrent posterior subluxa tion in a consecutive series of twenty-six shoulders in twenty-four patient s were reviewed. Eighteen shoulders were on the dominant side. The average age of the patients was twenty-four Sears (range, fifteen to thirty-three y ears). All of the patients had involuntary as well as voluntary posterior i nstability, but none had a psychiatric disorder. Only five patients had sus tained a definite injury that had initiated the instability. Seven shoulder s had had previous operations. A program of nonoperative treatment for a du ration of at least three months had failed to control the symptoms in all p atients. The twenty-six shoulders were treated with a posterior-inferior ca psular shift procedure, which included repair of a so-called posterior Bank art lesion in seven shoulders. In addition, one of the shoulders had a post erior bone block and three shoulders (in two patients) had an osteotomy of the posterior part of the glenoid because of excessive glenoid retroversion . The outcome was assessed by means of a personal interview and a clinical examination, which included calculations of a score according to the system of Constant and Murley and the performance of the Simple Shoulder Test, an d by means of a radiographic examination, with standardized radiographs and computerized tomography scanning. Results: At an average of 7.6 years (range, 1.8 to 14.6 sears) after the op eration, the patients estimated that the function of the shoulder was an av erage of 86 percent of that of a normal shoulder. The average relative scor e according to the system of Constant and Murley was 91 percent. The subjec tive result was excellent for sixteen shoulders, good for eight, and fair f or two. More than half of all of the patients were able to perform all acti vities of the Simple Shoulder Test, but eight patients (eight shoulders; 31 percent) still had discomfort at night. Five patients (21 percent) changed their profession because of the shoulder. All but one shoulder had a nearl y normal active range of motion. The instability recurred in six (23 percen t) of the twenty-six shoulders; three recurrences were in shoulders that ha d had a primary operation, and three were in shoulders that had had an oper ation on the posterior aspect of the shoulder before the index procedure. T he instability did not recur in four shoulders that had had previous operat ions on the anterior aspect of the shoulder. The subjective shoulder value, which was the patient's estimation of the va lue of the affected shoulder as a percentage of that of an entirety normal shoulder, was significantly higher for the stable shoulders (91 percent) th an for the unstable shoulders (72 percent) (p < 0.05). The relative score a ccording to the system of Constant and Murley was also higher for the stabl e shoulders (93 percent) than for the unstable shoulders (87 percent), but the difference was not found to be significant, with the numbers available. The joints were found to be well centered radiographically, and only six s houlders showed minimum signs of osteoarthritis. Computerized tomography sc anning revealed an average glenoid retroversion of 3.2 degrees (range, 17 d egrees of retroversion to 22 degrees of anteversion). When only the shoulde rs that had not had a posterior bone block or an osteotomy of the posterior aspect of the glenoid were considered, the average glenoid retroversion of those that had recurrent instability was 12.5 degrees,whereas it was only 6.2 degrees for those that remained stable (p < 0.05). Conclusions: Overall, operative correction of voluntary posterior instabili ty of the shoulder yielded very satisfactory intermediate-term clinical res ults. Recurrence was associated with a previous operation on the posterior aspect of the shoulder or with a new traumatic injury of an involved should er on the dominant side. The prevalence of recurrence did not increase over time, and clinically detectable osteoarthritis did not develop.