JBJS | Posterior-Inferior Capsular Shift for the Treatment of Recurrent, Voluntary Posterior Subluxation of the Shoulder*

The Journal of Bone & Joint Surgery, Volume 82, Issue 1

Articles | January 01, 2000

Posterior-Inferior Capsular Shift for the Treatment of Recurrent, Voluntary Posterior Subluxation of the Shoulder*

BRUNO FUCHS, M.D.†; BERNHARD JOST, M.D.†; CHRISTIAN GERBER, M.D.†, ZURICH, SWITZERLAND

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Investigation performed at the Department of Orthopedics, University of Zurich, Zurich

The Journal of Bone & Joint Surgery. 2000; 82:16-25

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Abstract

Background: The treatment of recurrent posterior instability of the shoulder, especially when it is associated with voluntary subluxation, remains controversial, and operative correction generally is not advised.

Methods: The results of operative correction of recurrent posterior subluxation in a consecutive series of twenty-six shoulders in twenty-four patients were reviewed. Eighteen shoulders were on the dominant side. The average age of the patients was twenty-four years (range, fifteen to thirty-three years). All of the patients had involuntary as well as voluntary posterior instability, but none had a psychiatric disorder. Only five patients had sustained a definite injury that had initiated the instability. Seven shoulders had had previous operations. A program of nonoperative treatment for a duration of at least three months had failed to control the symptoms in all patients. The twenty-six shoulders were treated with a posterior-inferior capsular shift procedure, which included repair of a so-called posterior Bankart lesion in seven shoulders. In addition, one of the shoulders had a posterior 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, and 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 years) after the operation, the patients estimated that the function of the shoulder was an average of 86 percent of that of a normal shoulder. The average relative score according to the system of Constant and Murley was 91 percent. The subjective result was excellent for sixteen shoulders, good for eight, and fair for two. More than half of all of the patients were able to perform all activities 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 nearly normal active range of motion. The instability recurred in six (23 percent) of the twenty-six shoulders; three recurrences were in shoulders that had had a primary operation, and three were in shoulders that had had an operation on the posterior aspect of the shoulder before the index procedure. The instability did not recur in four shoulders that had had previous operations on the anterior aspect of the shoulder.

The subjective shoulder value, which was the patient's estimation of the value of the affected shoulder as a percentage of that of an entirely normal shoulder, was significantly higher for the stable shoulders (91 percent) than for the unstable shoulders (72 percent) (p < 0.05). The relative score according to the system of Constant and Murley was also higher for the stable 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 shoulders showed minimum signs of osteoarthritis. Computerized tomography scanning revealed an average glenoid retroversion of 3.2 degrees (range, 17 degrees of retroversion to 22 degrees of anteversion). When only the shoulders 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 instability of the shoulder yielded very satisfactory intermediate-term clinical results. Recurrence was associated with a previous operation on the posterior aspect of the shoulder or with a new traumatic injury of an involved shoulder on the dominant side. The prevalence of recurrence did not increase over time, and clinically detectable osteoarthritis did not develop.

Figures in this Article

Introduction

Introduction | Materials and Methods | Results | Discussion | References

Recurrent posterior subluxation of the shoulder is rare^9,19. There is no general agreement regarding the classification and the terminology associated with the condition because of the many variables that may or may not be present, such as trauma, multidirectional hyperlaxity, unidirectional or multidirectional instability, the ability to subluxate the shoulder voluntarily, and intentional or only positional voluntary instability. It is difficult to integrate all of these variables into a generally accepted and reproducible classification system. Although the results of treatment often are not reported for one well defined variant of the condition, it is generally accepted that patients who have the ability to subluxate the shoulder voluntarily are at particularly high risk for failure of treatment. Nonetheless, such patients may be painfully disabled and may not respond to nonoperative management. The purpose of the present study was to report the long-term clinical and radiographic outcome of operative repair performed by the same surgeon in a consecutive series of twenty-four patients (twenty-six shoulders) with voluntary posterior subluxation of the shoulder.

*No benefits in any form have been received or will be received from a commercial party related directly or indirectly to the subject of this article. Funds were received in total or partial support of the research or clinical study presented in this article. The funding source was Verein Balgrist, Zurich, Switzerland.

†Department of Orthopedics, University of Zurich, Balgrist, Forchstrasse 340, 8008 Zurich, Switzerland. E-mail address for Dr. Gerber: cgerber@balgrist.unizh.ch.

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FIG1-A:: Fig. 1-A: Photographs showing a patient who was able to voluntarily subluxate the shoulder posteriorly by internal rotation and flexion (Fig. 1-A) and to relocate it by external rotation, adduction, and flexion (Fig. 1-B). This finding was seen in all patients in this series.

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FIG1-B:: Fig. 1-B: Photographs showing a patient who was able to voluntarily subluxate the shoulder posteriorly by internal rotation and flexion (Fig. 1-A) and to relocate it by external rotation, adduction, and flexion (Fig. 1-B). This finding was seen in all patients in this series.

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FIG2-A:: Fig. 2-A: Illustrations showing the posterior-inferior capsular shift procedure as performed in the present study. The posterior and lateral aspects of the deltoid muscle are detached, the infraspinatus tendon is released from its insertion, and the tendon is reflected medially (Fig. 2-A). The teres minor musculotendinous unit is not detached. Dissection is performed between the infraspinatus tendon and the capsule. The capsule is opened with a T-shaped incision, creating a superior flap (A) and an inferior flap (B). The superior flap is then shifted inferiorly, and the inferior flap is shifted superiorly (Fig. 2-B).

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FIG2-B:: Fig. 2-B: Illustrations showing the posterior-inferior capsular shift procedure as performed in the present study. The posterior and lateral aspects of the deltoid muscle are detached, the infraspinatus tendon is released from its insertion, and the tendon is reflected medially (Fig. 2-A). The teres minor musculotendinous unit is not detached. Dissection is performed between the infraspinatus tendon and the capsule. The capsule is opened with a T-shaped incision, creating a superior flap (A) and an inferior flap (B). The superior flap is then shifted inferiorly, and the inferior flap is shifted superiorly (Fig. 2-B).

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FIG 3:: Fig. 3 Intraoperative photograph of the glenohumeral joint after the T-shaped incision was created in the posterior aspect of the capsule. The humeral head (arrowhead) is retracted forward with a ring retractor. The posterior aspect of the labrum (within the forceps) is avulsed from the posterior aspect of the glenoid rim. Such posterior lesions needed repair in seven of the twenty-six shoulders in the present study.

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FIG4:: Fig. 4 Photograph made after the operation, showing a patient wearing a splint that prevented inferior traction and internal rotation of the arm for six weeks. After removal of the suction drain, the patients were allowed to remove the splint to perform external rotation movements.

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FIG5-A:: Fig. 5-A A preoperative arthro-computerized tomography scan showing a very wide capsule and a rounded but otherwise normal posterior aspect of the labrum (arrowhead).

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FIG5-B:: Fig. 5-B Intraoperative photograph showing the very large inferior flap (arrowhead) of the posterior aspect of the capsule and an intact posterior portion of the labrum.

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TABLE I: CLINICAL AND RADIOGRAPHIC OUTCOME DATA*

*Cases 1 through 19 are primary operations, and Cases 20 through 26 are revision operations.†The value of the shoulder was rated by the patient as a percentage of that of a normal shoulder.‡The angle was measured at the midglenoid level.§The patient was interviewed on the telephone after 125 months, with the most recent clinical examination at sixty-six months.#Only postoperative radiographs were available.**The patient was evaluated clinically but not radiographically because she was pregnant.

Case	Gender, Age (yrs.)	Dominant Limb	Duration of Follow-up (mos.)	Recurrence	Patient Satisfaction	Subjective Shoulder Value† (percent)	Score According to System of Constant and Murley⁷				Range of Motion (degrees)				Glenoid Version‡ (degrees)
Relative Score (percent)	Pain (points)	Activities of Daily Living (points)	Internal Rotation (points)	Flexion	Abduction	External Rotation	Internal Rotation
1	M, 24	Yes	32	No	Good	75	95	13	9	8	155	155	40	90	-8
2	M, 23	Yes	56	Yes	Fair	70	100	13	10	6	155	140	70	90	-11
3	F, 28	No	104	No	Excellent	95	95	15	10	10	160	165	75	85	1
4§	F, 23	No	66	No	Excellent	90	88	15	10	10	170	180	75	90	—
5	M, 21	Yes	103	Yes	Good	70	96	10	9	8	155	140	60	90	-10
6	M, 29	Yes	175	No	Good	80	97	5	7	8	160	150	60	90	18
7	M, 31	No	154	No	Excellent	99	99	13	10	10	170	170	50	90	21
8	F, 15	Yes	112	No	Excellent	95	85	15	10	10	165	170	90	90	-6
9	F, 18	No	77	No	Excellent	95	84	15	10	10	165	170	90	90	-2
10	M, 24	Yes	69	No	Good	95	95	15	9	10	165	150	60	65	-10
11#	M, 28	Yes	99	No	Excellent	100	95	15	10	10	175	175	60	70	—
12	M, 24	Yes	100	No	Good	95	97	14	10	8	175	175	45	65	-15
13	M, 22	No	175	No	Excellent	80	100	15	10	10	175	175	70	80	0
14	F, 24	Yes	32	No	Excellent	80	74	10	8	8	160	140	50	65	-9
15	M, 17	Yes	107	Yes	Fair	80	86	11	8	10	165	160	70	80	-17
16	M, 30	Yes	125	No	Excellent	95	98	15	10	10	175	175	80	65	-12
17	F, 17	Yes	102	No	Excellent	95	88	14	10	10	165	160	75	90	-2
18**	F, 26	Yes	65	No	Good	90	93	14	10	8	175	175	50	90	—
19	M, 24	Yes	21	No	Excellent	100	99	11	10	10	170	170	75	95	-9
20	F, 25	Yes	109	Yes	Excellent	70	59	15	8	6	90	60	30	80	22
21	M, 21	No	75	No	Excellent	90	92	15	10	8	165	170	50	100	-8
22	F, 21	No	74	No	Excellent	100	90	15	10	10	175	170	70	95	-3
23	F, 30	Yes	57	Yes	Good	60	88	10	8	10	170	170	50	105	-12
24	M, 32	Yes	34	No	Excellent	80	87	8	9	10	160	160	90	60	-6
25	M, 33	Yes	118	Yes	Good	80	93	10	9	10	160	165	45	110	6
26	M, 24	No	121	No	Excellent	89	100	15	8	10	160	165	45	90	-1
Average	24.4		91			86	91	12.9	9.3	9.2	163	160	63	85	-3.2

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TABLE I: CLINICAL AND RADIOGRAPHIC OUTCOME DATA*

Case	Gender, Age (yrs.)	Dominant Limb	Duration of Follow-up (mos.)	Recurrence	Patient Satisfaction	Subjective Shoulder Value† (percent)	Score According to System of Constant and Murley⁷				Range of Motion (degrees)				Glenoid Version‡ (degrees)
Relative Score (percent)	Pain (points)	Activities of Daily Living (points)	Internal Rotation (points)	Flexion	Abduction	External Rotation	Internal Rotation
1	M, 24	Yes	32	No	Good	75	95	13	9	8	155	155	40	90	-8
2	M, 23	Yes	56	Yes	Fair	70	100	13	10	6	155	140	70	90	-11
3	F, 28	No	104	No	Excellent	95	95	15	10	10	160	165	75	85	1
4§	F, 23	No	66	No	Excellent	90	88	15	10	10	170	180	75	90	—
5	M, 21	Yes	103	Yes	Good	70	96	10	9	8	155	140	60	90	-10
6	M, 29	Yes	175	No	Good	80	97	5	7	8	160	150	60	90	18
7	M, 31	No	154	No	Excellent	99	99	13	10	10	170	170	50	90	21
8	F, 15	Yes	112	No	Excellent	95	85	15	10	10	165	170	90	90	-6
9	F, 18	No	77	No	Excellent	95	84	15	10	10	165	170	90	90	-2
10	M, 24	Yes	69	No	Good	95	95	15	9	10	165	150	60	65	-10
11#	M, 28	Yes	99	No	Excellent	100	95	15	10	10	175	175	60	70	—
12	M, 24	Yes	100	No	Good	95	97	14	10	8	175	175	45	65	-15
13	M, 22	No	175	No	Excellent	80	100	15	10	10	175	175	70	80	0
14	F, 24	Yes	32	No	Excellent	80	74	10	8	8	160	140	50	65	-9
15	M, 17	Yes	107	Yes	Fair	80	86	11	8	10	165	160	70	80	-17
16	M, 30	Yes	125	No	Excellent	95	98	15	10	10	175	175	80	65	-12
17	F, 17	Yes	102	No	Excellent	95	88	14	10	10	165	160	75	90	-2
18**	F, 26	Yes	65	No	Good	90	93	14	10	8	175	175	50	90	—
19	M, 24	Yes	21	No	Excellent	100	99	11	10	10	170	170	75	95	-9
20	F, 25	Yes	109	Yes	Excellent	70	59	15	8	6	90	60	30	80	22
21	M, 21	No	75	No	Excellent	90	92	15	10	8	165	170	50	100	-8
22	F, 21	No	74	No	Excellent	100	90	15	10	10	175	170	70	95	-3
23	F, 30	Yes	57	Yes	Good	60	88	10	8	10	170	170	50	105	-12
24	M, 32	Yes	34	No	Excellent	80	87	8	9	10	160	160	90	60	-6
25	M, 33	Yes	118	Yes	Good	80	93	10	9	10	160	165	45	110	6
26	M, 24	No	121	No	Excellent	89	100	15	8	10	160	165	45	90	-1
Average	24.4		91			86	91	12.9	9.3	9.2	163	160	63	85	-3.2

Materials and Methods

Introduction | Materials and Methods | Results | Discussion | References

We reviewed the results for twenty-six shoulders in twenty-four consecutive patients who had had operative treatment for recurrent posterior subluxation of the shoulder that had interfered with their normal professional or daily activities, or both. All of the patients met the criteria for inclusion in the study, which were the occurrence of involuntary, painful, and disabling posterior subluxations during activities of daily living that involved forward elevation and internal rotation of the arm; the ability to voluntarily subluxate the shoulder posteriorly during flexion and internal rotation of the arm and to voluntarily relocate the shoulder by external rotation, adduction, and flexion (Figs. 1-A and 1-B); the absence of an overt psychiatric condition; the failure to respond to nonoperative treatment for a duration of at least three months; and operative repair performed by one of us (C. G.) between January 1982 and December 1995.

All patients who had recurrent locked posterior dislocations, as defined by the need for an assisted reduction, were excluded. Also, patients who had the most frequently addressed, purely involuntary variant, apprehension without the ability to visibly reproduce the posterior subluxation, were excluded.

At the time of the operation, the average age of the fifteen men and nine women was 24.4 years (range, fifteen to thirty-three years). One man (Cases 6 and 7) and one woman (Cases 8 and 9) had bilateral involvement. Eighteen shoulders were on the dominant side. In five shoulders, the first episode of posterior subluxation had followed a traumatic injury that the patient considered to be severe enough to dislocate a normal joint. In twenty-one shoulders, the onset was insidious, without any documented trauma. All of the patients were referred after previous treatment. Eighteen patients (nineteen shoulders) had not been considered for operative treatment by their treating physicians because their ability to actively subluxate the shoulder had suggested a psychiatric disorder.

Preoperatively, active flexion averaged 161 degrees (range, 50 to 180 degrees); active abduction averaged 150 degrees (range, 60 to 180 degrees); and external rotation, measured passively with the arm at the side and the scapula fixed to the thoracic cage, averaged 63 degrees (range, 10 to 100 degrees). The scores according to the system of Constant and Murley⁷ and the preoperative measurements of strength were unavailable for the patients who had long-term follow-up because these parameters were not introduced into clinical practice until after this study had begun. Seven shoulders had had a total of thirteen previous operations. Four shoulders had had a total of five anterior reconstructions of the shoulder, which had failed to correct the preoperative symptoms. None of them showed any objective evidence of anterior instability (a Hill-Sachs lesion or a Bankart lesion) at the time of the index procedure. Three shoulders had had a posterior operation. These shoulders included one (Case 23) that had had an unsuccessful posterior arthroscopic shaving procedure. In the second shoulder (Case 20), which had had two previous operations including a posterior bone block together with an osteotomy of the posterior aspect of the glenoid and a posterior arthroscopic shaving procedure, an operative injury to the suprascapular nerve led to a denervation of the infraspinatus muscle with resultant severe weakness of external rotation and limitation of flexion to 50 degrees. In the third shoulder (Case 25), five previous posterior operations (including a posterior bone block) had resulted in recurrence of instability with posterior detachment and weakness of the deltoid muscle. The latter two shoulders had an unfavorable outcome after our revision with use of the posterior-inferior capsular shift procedure.

All patients participated in a rehabilitation program to strengthen the rotator cuff muscles and the deltoid muscle as well as to train the patient to perform specific active movement patterns that avoided the combination of flexion and internal rotation during flexion of the arm. An operation was considered only if participation in such a treatment program for at least three months had failed to relieve the symptoms.

All patients were evaluated for the purpose of the present study by two examiners (B. F. and B. J.) other than the operating surgeon (C. G.). One patient could be interviewed only by telephone, one patient could be examined clinically but not radiographically because she was pregnant, and the remaining twenty-two patients (twenty-four shoulders) were examined clinically and radiographically.

The clinical assessment was based on a structured interview, which included the Simple Shoulder Test¹⁵ (a standardized self-assessment inventory of the function of the shoulder), and a detailed, standardized physical examination, which included scoring of the function of the shoulder according to the system of Constant and Murley⁷. The assessment of pain-free active flexion and abduction was performed with the patient sitting. The range of flexion (in the sagittal plane) was measured as the angle between the humeral shaft and the midthoracic line (not the vertical) to compensate for a potential hyperlordosis. Abduction was measured, with simultaneous maximum abduction of both arms, as the angle of the humeral shaft with the midthoracic line. Functional external rotation was measured, according to the system of Constant and Murley⁷, by bringing the hand behind the head and then above the head without allowing the hand to touch the head. The amount of active internal rotation was determined according to the spinous process that could be reached by the thumb without pain.

Strength was assessed with the patient standing and the arm abducted to 90 degrees in the scapular plane, the elbow extended, and the forearm pronated. An Isobex dynamometer (Cursor SA, Bern, Switzerland) was used, and resistance was applied at the wrist. Three measurements of five seconds' duration (the B mode of the device) were averaged to determine the strength of abduction. One point was given for each 0.45 kilogram of strength measured, and the total score was recorded. In addition, the score for each patient was related to age and gender-matched normal values, as identified by Constant and Murley⁷, which allowed the score to be expressed as a percentage of normal. The patients then were asked to estimate the value of the shoulder as a percentage of that of an entirely normal shoulder. This value was called the subjective shoulder value. The load and shift test was performed to assess the degree of translation. Grade 0 indicated that no translation could be detected; grade 1, that the humeral head moved slightly up while still facing the glenoid (less than one centimeter of translation); grade 2, that the humeral head moved up the glenoid face but not over the rim (one to two centimeters of translation); and grade 3, that the head was brought out of contact with the glenoid (more than two centimeters of translation).

Routine radiographs of the shoulder (true anteroposterior radiographs made with the arm in neutral, internal, and external rotation and a true lateral radiograph of the scapula [the so-called Y view]) and an axillary radiograph were made for all patients preoperatively and for all but two patients postoperatively. Degenerative changes were classified according to the system of Samilson and Prieto²¹. Additionally, at the time of follow-up, a computerized tomography scan was performed for twenty-three shoulders to analyze glenoid version as well as osseous and labral abnormalities, including posterior glenoid hypoplasia as described by Edelson⁸.

Statistical comparison between stable and unstable shoulders was performed with use of the Mann-Whitney U test. The level of significance was set at p < 0.05.

Operative Technique

The patient was positioned in lateral decubitus with the arm draped free and the involved shoulder pointing upward. A posterior approach was used in all patients. The oblique skin incision, beginning at the acromial angle, was directed medially and distally about ten centimeters at an angle of 45 degrees to the scapular spine. The posterior portion and part of the lateral portion of the deltoid muscle were detached from the scapular spine and the posterior aspect of the acromion and were retracted. The tendon of the infraspinatus muscle was identified and was released from its insertion on the greater tuberosity, with the capsule left intact. No muscle or tendon tissue was left on the capsule, but the dissection between the capsule and the infraspinatus muscle was anatomical. The posterior aspect of the capsule was then incised horizontally at the midglenoid level, from the site of the glenoid attachment to the site of the humeral attachment (Figs. 2-A and 2-B). Subsequently, the capsule was incised vertically about five millimeters medial to its attachment on the humerus, with careful protection of the axillary nerve. This T-shaped incision yielded a superior flap and an inferior flap. The humeral head then was dislocated posteriorly and was fully internally rotated to assess whether there was an impression fracture of the anterior aspect of the humeral head. A ring retractor was inserted into the joint to subluxate the humeral head anteriorly to allow inspection of the joint. The stability of the biceps tendon, the anterior aspect of the glenoid labrum, the cartilage, and the posterior aspect of the labrum as well as the capsule were assessed. If the posterior aspect of the labrum together with the capsule was detached from the bone (a so-called posterior Bankart lesion [Fig. 3]), it was repaired to the posterior aspect of the glenoid rim with use of bone anchors and nonabsorbable sutures (seven shoulders). If the anterior aspect of the labrum was detached, it also was repaired, either through the posterior approach or with an additional transcutaneous placement of a suture anchor, which was controlled visually through the posterior approach (three shoulders). Thereafter, the superior flap was shifted inferiorly and fixed to the lateral rim of the capsule so that, with the arm in neutral rotation, it could still be elevated 0.5 centimeter from the centered humeral head. Then the inferior flap was shifted superiorly and fixed more superiorly than its original position to the lateral, remaining aspect of the capsule.

The lateral capsular overlap was usually between one and two centimeters. In one shoulder (Case 26), in which the posterior-inferior aspect of the glenoid seemed particularly worn, a posterior bone block was added, and, in three shoulders (Cases 6, 7, and 14) in two patients, an opening wedge osteotomy of the posterior part of the glenoid was added with use of a graft that had a mediolateral diameter of no more than one centimeter, which had been obtained from the scapular spine. The infraspinatus tendon was then repaired anatomically, the deltoid muscle was reattached with transosseous sutures to the scapular spine in an anatomical position, and the skin was closed over a suction drain.

Postoperative Rehabilitation

Postoperatively, the arm was placed in slight abduction and neutral rotation in a plastic splint (Fig. 4), to prevent inferior stresses on the repair, for six weeks. On the second postoperative day, passive range-of-motion exercises that avoided internal rotation were begun with the splint removed and were continued for six weeks. After six weeks, the splint was removed and internal rotation and strengthening exercises were started. Sports requiring overhead use of the shoulder were not allowed for six months. Postoperatively, the average duration of sick leave was 4.5 months (range, 0.5 to twelve months).

Results

Introduction | Materials and Methods | Results | Discussion | References

Operative Findings

The posterior part of the deltoid muscle was found to be detached and fibrotic in one patient. The infraspinatus muscle was weak and fibrotic in the same patient, and it was denervated in another patient. The capsule was found to be thin and could be elevated from the posterior aspect of the humeral head by more than five millimeters with the arm in neutral rotation in twenty shoulders. The capsule was not definitely abnormal in six shoulders. The posterior aspect of the labrum was normal in thirteen shoulders (50 percent) (Figs. 5-A and 5-B) and abnormal in thirteen shoulders. In seven shoulders (27 percent), it appeared to be not only degenerated but also detached and was treated with a labral reinsertion with use of bone anchors and nonabsorbable sutures. The anterior aspect of the labrum was abnormal in six shoulders and was repaired with use of the Bankart technique through the posterior approach in three shoulders. The posterior-inferior aspect of the glenoid appeared to be flattened in two shoulders. In one of these shoulders, an extra-articular bone block was added to the capsular shift. A small reverse Hill-Sachs lesion was noted in two shoulders and was not treated.

Clinical Outcome (Table I)

At an average of 7.6 years (range, 1.8 to 14.6 years) after the operation, the subjective result was excellent for sixteen shoulders (62 percent), good for eight (31 percent), and fair for two (8 percent). Interestingly, five of the seven shoulders in which the index procedure had been a revision were subjectively rated as excellent and the other two were rated as good, although at least one of the shoulders that was subjectively rated as excellent was objectively rated as a failure. All eight shoulders on the nondominant side were rated as excellent. Eight of the eighteen shoulders on the dominant side were rated as excellent; eight, as good; and two, as fair. Five patients, however, changed their profession to a less strenuous one. Three of these patients had had a clinical recurrence, and the other two had a stable shoulder but thought that less strenuous work probably would be better. No patient was unemployed or was collecting a disability pension. All but one shoulder had a nearly normal active range of motion. Three patients, all of whom had had a revision, were limited in their sports activities; two of them were so limited because of a recurrence of the instability. The overall relative score according to the system of Constant and Murley⁷ was 91 percent, which corresponded well with a subjective shoulder value of 86 percent of a normal shoulder.

Stability was restored, both subjectively and objectively, in twenty shoulders, but the instability recurred in six shoulders (23 percent), in four men and two women. Three of the six shoulders had had a previous operation, so the rate of recurrence in the shoulders in which the inferior capsular shift was a revision procedure was three of seven; all three shoulders that had been operated on because of posterior instability had a recurrence, whereas all that (erroneously) had had an anterior procedure were successfully stabilized. The rate of recurrence in the shoulders that had had a primary procedure was three of nineteen. Recurrence occurred only in shoulders that were on the dominant side. The two patients who had had preoperative destruction of the deltoid and infraspinatus muscles had a recurrence that was not related to trauma (at nine and twelve months postoperatively). The other four patients had a traumatic event that precipitated the recurrence (within the first year in two shoulders, two years after the operation in one shoulder, and four years after the operation in one). All four patients clearly remembered this traumatic event but thought that it had not been severe enough to cause a subluxation of a normal shoulder.

The subjective shoulder value was found to be significantly higher for the stable shoulders (91 percent) than for the unstable shoulders (72 percent) (p < 0.05). A comparison of the stable and unstable shoulders revealed that flexion, abduction, and external rotation were substantially poorer if the instability recurred. Conversely, with the limited number of patients available for study, we could not detect a significant difference between the stable and the unstable shoulders with respect to the overall score according to the system of Constant and Murley⁷, the result on the Simple Shoulder Test¹⁵, the type of procedure (primary or revision), or the age or gender of the patient.

The patients performed an average of 88 percent (range, 42 to 100 percent) of all of the activities required in the Simple Shoulder Test¹⁵; fifteen (58 percent) of the twenty-six shoulders were in patients who could complete all tasks without restriction. Eight patients (eight shoulders; 31 percent) were restricted in the ability to sleep on the involved shoulder. Five patients (five shoulders; 19 percent) perceived minor discomfort when washing the back, indicating a restriction of internal rotation.

Radiographic Outcome (Table I)

The conventional radiographs made at the follow-up examinations revealed mild osteoarthritis in six patients (one unstable and five stable shoulders). The degenerative changes in the joint had no effect on any clinical parameters. Computerized tomography scanning, which was performed for twenty-three shoulders, revealed an average glenoid retroversion of 3.2 degrees, with fifteen shoulders (65 percent) within the normal limit of ±10 degrees. Localized glenoid hypoplasia was identified in seventeen (74 percent) of the twenty-three shoulders. No static anterior or superior subluxation of the humeral head was seen radiographically. The average glenoid retroversion of the thirteen shoulders that were stable after an isolated posterior-inferior capsular shift procedure was 6.2 degrees; the retroversion of the four shoulders that were unstable after an isolated posterior-inferior capsular shift procedure was 12.5 degrees (p < 0.05). Pain and function were not related to glenoid version.

Complications

None of the patients had a systemic complication, infection, or neurological injury. Widening of the scar was frequently observed, but no patient complained about the cosmetic appearance. Five shoulders (19 percent) had six reoperations. An anterior subcoracoid impingement developed in one patient who had had a glenoid osteotomy, and it was successfully relieved by coracoplasty. A second patient had an arthroscopic revision because of residual instability, and a repeat fixation of the anterosuperior aspect of the labrum restored subjective stability. A third patient had an anterior-inferior capsular shift procedure seven months after the index procedure because of residual multidirectional instability. Three months after this second operation, he sustained a severe traumatic injury with avulsion of the subscapularis tendon, which was operatively reattached; the subjective outcome was excellent. A fourth patient, who had had five posterior operations before the index operation, did well for twenty-one months and then posterior subluxation developed again without any apparent trauma. He had a revision operation with an additional anterior-inferior capsular shift procedure. Stability was not restored, and the subjective result was fair. The fifth patient, who previously had had an anterior procedure, felt that the shoulder was weak but stable one year after the posterior-inferior capsular shift procedure. Weakness of the subscapularis muscle was diagnosed, and the subscapularis tendon was reinserted, with an excellent result.

Discussion

Introduction | Materials and Methods | Results | Discussion | References

The operative treatment of voluntary posterior instability of the shoulder remains controversial. There is no doubt that many patients do well without an operation and that a nonoperative treatment regimen should be attempted before an operation is considered^2,6,12,14. Many patients can obtain subjective improvement without an operation, although the posterior subluxation is not necessarily eliminated. Many operative techniques for shoulders that are resistant to nonoperative treatment have been described, and numerous outcome studies are available^{1,4,10,12,14,16,17,22,23}. Reports on the success of soft-tissue procedures have varied, with rates of recurrence of instability ranging from none of fifteen¹⁷ to eighteen (72 percent) of twenty-five patients¹⁴.

Patients who are able to subluxate the shoulder voluntarily rarely need an operation^6,11,20 because they often do not have enough discomfort to warrant operative treatment, the risk of recurrence is very high, and the condition may be due to a psychiatric, behavioral abnormality²⁰. Profound psychiatric problems have been found to be rare in children who voluntarily subluxate the shoulder^13,20. We found that this was true for the present series of adult patients as well. We thought that a preoperative psychiatric workup was justified for only two patients in our series. The evaluations revealed no emotional disturbance in either patient. There was a suspicion that a third patient, in whom the instability recurred after the repair, had an emotional problem, but it was not believed to have led to the recurrence. The findings in the present series demonstrated that patients who have posterior instability of the shoulder should not be limited to nonoperative management solely because they are able to subluxate the shoulder voluntarily. The outcome of operative management in patients who have voluntary subluxation of the shoulder and no evident emotional problem is comparable with that in patients who have the purely involuntary form of subluxation, and the outcomes in both groups represent a relevant improvement compared with the preoperative state.

Structurally, posterior stability of the shoulder depends on the integrity of various anatomical structures⁹. The findings of several biomechanical studies have suggested that, although it is thin (measuring only about one and one-half millimeters in thickness³), the posteroinferior aspect of the capsule of the glenohumeral joint and especially the posterior band of the inferior glenohumeral ligament complex is the most effective structure for providing stability in flexion, internal rotation, and adduction^5,18,24. Weber and Caspari²⁷ demonstrated, in a cadaveric model, that the posteroinferior aspect of the capsule may be damaged by the forces causing posterior dislocation of the shoulder. Biomechanical data and clinical reports^5,26 have suggested that clinical instability is caused by elongation of the posteroinferior capsulolabral complex. In our series, the posteroinferior capsulolabral complex was almost always found to be abnormal on intraoperative examination. Although this is very difficult to quantitate, we intraoperatively estimated that the complex was pathologically weak or redundant in eighteen (69 percent) of the twenty-six shoulders. This finding is in agreement with that of other investigators^4,19,25 and supports the concept of the posterior-inferior capsular shift procedure, which eliminates this capsular redundancy and allows plication of the capsule at a critical site.

Lesions of the posterior part of the labrum or so-called posterior Bankart lesions have been rarely reported. However, we found unequivocal abnormality of the posterior aspect of the labrum in thirteen (50 percent) of twenty-six shoulders and true detachments that needed repair in seven (27 percent). This finding is particularly surprising as approximately 80 percent of the patients in the present series did not have any history of major trauma.

The role of so-called excessive retroversion of the glenoid fossa remains unresolved. Computerized tomography scanning of the patients who did not have a posterior bone block or an osteotomy of the posterior aspect of the glenoid showed that excessive retroversion is not a prerequisite for voluntary posterior subluxation of the shoulder. In the shoulders that had a recurrence, however, the retroversion averaged 12.5 degrees (range, -10 to -17 degrees), whereas the stable shoulders had a significantly less retroverted glenoid (6.2 degrees; p < 0.05). Therefore, we concluded that we will add an osteotomy of the posterior aspect of the glenoid if retroversion of the glenoid is more than 10 degrees in such shoulders.

Clinically, the findings in our group of patients high-lighted several points. Many patients with recurrent posterior instability of the shoulder have previously had operative procedures for misdiagnosed anterior instability of the shoulder^4,11 or other abnormalities^4,12,25. It was noteworthy that, in the present series, an anterior operation did not preclude a good result after a posterior-inferior capsular shift and, in future reports, investigators may need to distinguish between previous anterior and posterior operations on the shoulder in an assessment of the value of this procedure as a revision operation. We had no patient, however, in whom the anterior operation restricted internal rotation markedly. If internal rotation is severely limited by a previous anterior operation, the approach to the problem and the prognosis may be much different.

The rates of recurrence after a posterior-inferior capsular shift procedure performed for recurrent posterior instability are higher than the rates of recurrence after anterior stabilization of the shoulder^4,17,25. Nonetheless, most shoulders are improved by the procedure and the patients are satisfied. The rate of recurrence after a posterior-inferior capsular shift performed as a posterior revision operation is prohibitive when the infraspinatus muscle or the posterior part of the deltoid muscle, or both, have been damaged. This observation agrees with that of the only other study, to our knowledge, that involved a substantial number of shoulders treated with this method⁴.

In our series, recurrence was observed only in shoulders on the dominant side. This finding suggests that repetitive, vigorous use of the shoulder may be a risk factor. We could not, however, document a greater probability for recurrence in patients who performed strenuous labor compared with those who performed office work or in men compared with women. The rate of recurrence did not increase with the duration of follow-up, as recurrences usually occurred early after the operation. It is improbable that, after 7.5 years postoperatively, the rate of recurrence will increase substantially. Conversely, the recurrences were related to more-or-less intense, work-related trauma, which seemed to affect the dominant arm more frequently than the nondominant arm.

We concluded that the posterior-inferior capsular shift procedure for the treatment of voluntary posterior instability of the shoulder yields highly satisfactory intermediate to long-term clinical results. Recurrence was associated with a new trauma to a dominant limb and with previous posterior operations, but there was no increase in the rate of recurrence over time and no development of clinically notable osteoarthritis. The ability to subluxate the shoulder voluntarily does not constitute a contraindication for operative correction if a patient is sufficiently disabled and does not obtain improvement from nonoperative treatment.

References

Introduction | Materials and Methods | Results | Discussion | References

Ahlgren, S. A.; Hedlund, T.; and Nistor, L.: Idiopathic posterior instability of the shoulder joint. Results of operation with posterior bone graft. Acta Orthop. Scandinavica,49: 600-603, 1978.49600 1978

Beall, M. S., Jr.; Diefenbach, G.; and Allen, A.: Electromyographic biofeedback in the treatment of voluntary posterior instability of the shoulder. Am. J. Sports Med.,15: 175-178, 1987.15175 1987 [PubMed]

Bigliani, L. U.; Pollock, R. G.; Soslowsky, L. J.; Flatow, E. L.; Pawluk, R. J.; and Mow, V. C.: Tensile properties of the inferior glenohumeral ligament. J. Orthop. Res.,10: 187-197, 1992.10187 1992 [PubMed]

Bigliani, L. U.; Pollock, G. R.; McIlveen, S. J.; Endrizzi, D. P.; and Flatow, E. L.: Shift of the posteroinferior aspect of the capsule for recurrent posterior glenohumeral instability. J. Bone and Joint Surg.,77-A: 1011-1020, July 1995.77-A1011 1995

Blasier, R. B.; Soslowsky, L. J.; Malicky, D. M.; and Palmer, M. L.: Posterior glenohumeral subluxation: active and passive stabilization in a biomechanical model. J. Bone and Joint Surg.,79-A: 433-440, March 1997.79-A433 1997

Burkhead, W. Z., Jr., and Rockwood, C. A., Jr.: Treatment of instability of the shoulder with an exercise program. J. Bone and Joint Surg.,74-A: 890-896, July 1992.74-A890 1992

Constant, C. R., and Murley, A. H.: A clinical method of functional assessment of the shoulder. Clin. Orthop.,214: 160-164, 1987.214160 1987 [PubMed]

Edelson, J. G.: Localized glenoid hypoplasia. An anatomic variation of possible clinical significance. Clin. Orthop.,321: 189-195, 1995.321189 1995 [PubMed]

Gerber, C.: L'instabilité postérieure de l'épaule. In Cahiers d'enseignement de la SOFCOT. No. 40, pp. 223-245. Paris, Expansion Scientifique Françcaise, 1991.

Gerber, C., and Lambert, S. M.: Allograft reconstruction of segmental defects of the humeral head for the treatment of chronic locked posterior dislocation of the shoulder. J. Bone and Joint Surg.,78-A: 376-382, March 1996.78-A376 1996

Hawkins, R. J.; Koppert, G.; and Johnston, G.: Recurrent posterior instability (subluxation) of the shoulder. J. Bone and Joint Surg.,66-A: 169-174, Feb. 1984.66-A169 1984

Hawkins, R. J., and Janda, D. H.: Posterior instability of the glenohumeral joint. A technique of repair. Am. J. Sports Med.,24: 275-278, 1996.24275 1996 [PubMed]

Huber, H., and Gerber, C.: Voluntary subluxation of the shoulder in children. A long-term follow-up study of 36 shoulders. J. Bone and Joint Surg.,76-B(1): 118-122, 1994.76-B(1)118 1994

Hurley, J. A.; Anderson, T. E.; Dear, W.; Andrish, J. T.; Bergfeld, J. A.; and Weiker, G. G.: Posterior shoulder instability. Surgical versus conservative results with evaluation of glenoid version. Am. J. Sports Med.,20: 396-400, 1992.20396 1992 [PubMed]

Matsen, F. A., III; Lippitt, S. B.; Sidles, J. A.; and Harryman, D. T., II: Evaluating the shoulder. In Practical Evaluation and Management of the Shoulder, pp. 1-17. Philadelphia, W. B. Saunders, 1994.

Mowery, C. A.; Garfin, S. R.; Booth, R. E.; and Rothman, R. H.: Recurrent posterior dislocation of the shoulder: treatment using a bone block. J. Bone and Joint Surg.,67-A: 777-781, June 1985.67-A777 1985

Neer, C. S., II, and Foster, C. R.: Inferior capsular shift for involuntary inferior and multidirectional instability of the shoulder. A preliminary report. J. Bone and Joint Surg.,62-A: 897-908, Sept. 1980.62-A897 1980

O'Brien, S. J.; Schwartz, R. S.; Warren, R. F.; and Torzilli, P. A.: Capsular restraints to anterior-posterior motion of the abducted shoulder: a biomechanical study. J. Shoulder and Elbow Surg.,4: 298-308, 1995.4298 1995

Pollock, R. G., and Bigliani, L. U.: Recurrent posterior shoulder instability. Diagnosis and treatment. Clin. Orthop.,291: 85-96, 1993.29185 1993 [PubMed]

Rowe, C. R.; Pierce, D. S.; and Clarke, J. G.: Voluntary dislocation of the shoulder. A preliminary report on a clinical, electromyographic, and psychiatric study of twenty-six patients. J. Bone and Joint Surg.,55-A: 445-460, April 1973.55-A445 1973

Samilson, R. L., and Prieto, V.: Dislocation arthropathy of the shoulder. J. Bone and Joint Surg.,65-A: 456-460, April 1983.65-A456 1983

Scott, D. J., Jr.: Treatment of recurrent posterior dislocations of the shoulder by glenoplasty. Report of three cases. J. Bone and Joint Surg.,49-A: 471-476, April 1967.49-A471 1967

Surin, V.; Blåder, S.; Markhede, G.; and Sundholm, K.: Rotational osteotomy of the humerus for posterior instability of the shoulder. J. Bone and Joint Surg.,72-A: 181-186, Feb. 1990.72-A181 1990

Terry, G. C.; Hammon, D.; France, P.; and Norwood, L. A.: The stabilizing function of passive shoulder restraints. Am. J. Sports Med.,19: 26-34, 1991.1926 1991 [PubMed]

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FIG5-A:: Fig. 5-A A preoperative arthro-computerized tomography scan showing a very wide capsule and a rounded but otherwise normal posterior aspect of the labrum (arrowhead).

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FIG5-B:: Fig. 5-B Intraoperative photograph showing the very large inferior flap (arrowhead) of the posterior aspect of the capsule and an intact posterior portion of the labrum.

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TABLE I: CLINICAL AND RADIOGRAPHIC OUTCOME DATA*

Case	Gender, Age (yrs.)	Dominant Limb	Duration of Follow-up (mos.)	Recurrence	Patient Satisfaction	Subjective Shoulder Value† (percent)	Score According to System of Constant and Murley⁷				Range of Motion (degrees)				Glenoid Version‡ (degrees)
Relative Score (percent)	Pain (points)	Activities of Daily Living (points)	Internal Rotation (points)	Flexion	Abduction	External Rotation	Internal Rotation
1	M, 24	Yes	32	No	Good	75	95	13	9	8	155	155	40	90	-8
2	M, 23	Yes	56	Yes	Fair	70	100	13	10	6	155	140	70	90	-11
3	F, 28	No	104	No	Excellent	95	95	15	10	10	160	165	75	85	1
4§	F, 23	No	66	No	Excellent	90	88	15	10	10	170	180	75	90	—
5	M, 21	Yes	103	Yes	Good	70	96	10	9	8	155	140	60	90	-10
6	M, 29	Yes	175	No	Good	80	97	5	7	8	160	150	60	90	18
7	M, 31	No	154	No	Excellent	99	99	13	10	10	170	170	50	90	21
8	F, 15	Yes	112	No	Excellent	95	85	15	10	10	165	170	90	90	-6
9	F, 18	No	77	No	Excellent	95	84	15	10	10	165	170	90	90	-2
10	M, 24	Yes	69	No	Good	95	95	15	9	10	165	150	60	65	-10
11#	M, 28	Yes	99	No	Excellent	100	95	15	10	10	175	175	60	70	—
12	M, 24	Yes	100	No	Good	95	97	14	10	8	175	175	45	65	-15
13	M, 22	No	175	No	Excellent	80	100	15	10	10	175	175	70	80	0
14	F, 24	Yes	32	No	Excellent	80	74	10	8	8	160	140	50	65	-9
15	M, 17	Yes	107	Yes	Fair	80	86	11	8	10	165	160	70	80	-17
16	M, 30	Yes	125	No	Excellent	95	98	15	10	10	175	175	80	65	-12
17	F, 17	Yes	102	No	Excellent	95	88	14	10	10	165	160	75	90	-2
18**	F, 26	Yes	65	No	Good	90	93	14	10	8	175	175	50	90	—
19	M, 24	Yes	21	No	Excellent	100	99	11	10	10	170	170	75	95	-9
20	F, 25	Yes	109	Yes	Excellent	70	59	15	8	6	90	60	30	80	22
21	M, 21	No	75	No	Excellent	90	92	15	10	8	165	170	50	100	-8
22	F, 21	No	74	No	Excellent	100	90	15	10	10	175	170	70	95	-3
23	F, 30	Yes	57	Yes	Good	60	88	10	8	10	170	170	50	105	-12
24	M, 32	Yes	34	No	Excellent	80	87	8	9	10	160	160	90	60	-6
25	M, 33	Yes	118	Yes	Good	80	93	10	9	10	160	165	45	110	6
26	M, 24	No	121	No	Excellent	89	100	15	8	10	160	165	45	90	-1
Average	24.4		91			86	91	12.9	9.3	9.2	163	160	63	85	-3.2

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TABLE I: CLINICAL AND RADIOGRAPHIC OUTCOME DATA*

Case	Gender, Age (yrs.)	Dominant Limb	Duration of Follow-up (mos.)	Recurrence	Patient Satisfaction	Subjective Shoulder Value† (percent)	Score According to System of Constant and Murley⁷				Range of Motion (degrees)				Glenoid Version‡ (degrees)
Relative Score (percent)	Pain (points)	Activities of Daily Living (points)	Internal Rotation (points)	Flexion	Abduction	External Rotation	Internal Rotation
1	M, 24	Yes	32	No	Good	75	95	13	9	8	155	155	40	90	-8
2	M, 23	Yes	56	Yes	Fair	70	100	13	10	6	155	140	70	90	-11
3	F, 28	No	104	No	Excellent	95	95	15	10	10	160	165	75	85	1
4§	F, 23	No	66	No	Excellent	90	88	15	10	10	170	180	75	90	—
5	M, 21	Yes	103	Yes	Good	70	96	10	9	8	155	140	60	90	-10
6	M, 29	Yes	175	No	Good	80	97	5	7	8	160	150	60	90	18
7	M, 31	No	154	No	Excellent	99	99	13	10	10	170	170	50	90	21
8	F, 15	Yes	112	No	Excellent	95	85	15	10	10	165	170	90	90	-6
9	F, 18	No	77	No	Excellent	95	84	15	10	10	165	170	90	90	-2
10	M, 24	Yes	69	No	Good	95	95	15	9	10	165	150	60	65	-10
11#	M, 28	Yes	99	No	Excellent	100	95	15	10	10	175	175	60	70	—
12	M, 24	Yes	100	No	Good	95	97	14	10	8	175	175	45	65	-15
13	M, 22	No	175	No	Excellent	80	100	15	10	10	175	175	70	80	0
14	F, 24	Yes	32	No	Excellent	80	74	10	8	8	160	140	50	65	-9
15	M, 17	Yes	107	Yes	Fair	80	86	11	8	10	165	160	70	80	-17
16	M, 30	Yes	125	No	Excellent	95	98	15	10	10	175	175	80	65	-12
17	F, 17	Yes	102	No	Excellent	95	88	14	10	10	165	160	75	90	-2
18**	F, 26	Yes	65	No	Good	90	93	14	10	8	175	175	50	90	—
19	M, 24	Yes	21	No	Excellent	100	99	11	10	10	170	170	75	95	-9
20	F, 25	Yes	109	Yes	Excellent	70	59	15	8	6	90	60	30	80	22
21	M, 21	No	75	No	Excellent	90	92	15	10	8	165	170	50	100	-8
22	F, 21	No	74	No	Excellent	100	90	15	10	10	175	170	70	95	-3
23	F, 30	Yes	57	Yes	Good	60	88	10	8	10	170	170	50	105	-12
24	M, 32	Yes	34	No	Excellent	80	87	8	9	10	160	160	90	60	-6
25	M, 33	Yes	118	Yes	Good	80	93	10	9	10	160	165	45	110	6
26	M, 24	No	121	No	Excellent	89	100	15	8	10	160	165	45	90	-1
Average	24.4		91			86	91	12.9	9.3	9.2	163	160	63	85	-3.2