Two hundred and sixteen patients (221 shoulders) were managed by us, between 1980 and 1994, with an anatomical capsular imbrication procedure for recurrent anterior glenohumeral subluxation or dislocation. All of the patients were managed operatively after a physician-directed rehabilitation program that emphasized strengthening of the three parts of the deltoid, the muscles of the rotator cuff, and the scapula-stabilizing muscles had failed. Failure of the rehabilitation program was characterized by symptomatic recurrent anterior glenohumeral subluxation or dislocation as well as by moderate-to-severe pain and weakness in the involved upper extremity when the shoulder was subjected to an anteriorly directed force by abduction and external rotation of the arm.
In eighteen of the 221 shoulders, the injury of the subscapularis tendon or muscle was the only tendon or muscle injury in addition to a tear of the anterior glenohumeral ligaments or capsulolabral detachment from the anterior aspect of the glenoid rim. Fourteen of the eighteen shoulders had what we considered to be an irreparable injury of the subscapularis muscle, and thirteen of them were available for long-term follow-up evaluation. For the purposes of the present study, we defined an irreparable injury as complete absence of the subscapularis muscle; that is, at the time of the operation, the subscapularis muscle was not discernible in its normal anatomical position overlying the anterior portion of the glenohumeral joint capsule. In each shoulder, there was dense connective scar tissue medial to the anterior aspect of the glenoid rim, and the subscapularis muscle could not be identified even after attempted dissection of this tissue. The remainder of the rotator cuff was intact and appeared normal. In one shoulder, the rupture of the subscapularis was diagnosed preoperatively on the basis of imaging studies as well as increased external rotation and decreased strength of internal rotation on physical examination. In the remaining shoulders, a rupture of the subscapularis tendon or muscle as an isolated injury of the rotator cuff was not suspected preoperatively. The inability to repair the ruptured subscapularis was determined at the time of the operation in all shoulders.
The patients included seven men and six women, and the average age at the time of the operation was forty-nine years (range, twenty-seven to eighty-six years). An operation was performed on eight right shoulders and on five left shoulders; nine operations were performed on the side of the dominant extremity. All but three of the patients had had two to six (average, three) previous reconstructions, including a Bristow procedure (seven shoulders), a Putti-Platt procedure (seven), a Magnuson-Stack procedure (four), a Bankart procedure (two), a Neer inferior capsular shift procedure (four), a posterior capsulorraphy (one), and an unspecified anterior reconstruction (six). Twelve patients were referred to our institution with records documenting repeated anterior dislocation according to the history, physical examination, and radiographs. The primary symptoms in all patients were activity-related pain in the shoulder, weakness, and apprehension when the arm was abducted and externally rotated. Eight patients had subjective numbness or tingling associated with pain in the involved extremity. None of the patients were able to throw overhead comfortably or to place the hand behind the head without moderate or severe discomfort associated with subluxation or dislocation of the shoulder. Twelve patients were unable to lift a ten-pound (4.5-kilogram) weight above shoulder height. Eleven had discomfort of the shoulder that awakened them when they rolled onto the involved side.
The mean range of motion was 140 degrees (range, 40 to 170 degrees) of elevation (the position between abduction and forward flexion that allowed the greatest excursion), 70 degrees (range, 50 to 90 degrees) of external rotation (with the elbow at the side), and internal rotation (with the patient sitting or standing) to the spinous process of the eighth thoracic vertebra (range, the fourth lumbar to the fourth thoracic vertebra). All patients demonstrated apprehension when the involved shoulder was subjected to an anteriorly directed force by abduction and external rotation of the arm.
The degree of glenohumeral laxity was determined with drawer testing. Grade-I laxity indicated translation of less than 50 per cent of the diameter of the humeral head from its articulation with the glenoid; grade-II laxity indicated translation of more than 50 per cent of the humeral-head diameter, but the joint was not dislocatable; and grade-III laxity indicated that the glenohumeral joint was dislocatable. Preoperatively, anterior laxity was classified as grade III in three shoulders and as grade II in seven; the laxity could not be determined for the remaining three shoulders because of pain and apprehension. After the induction of general anesthesia, grade-III laxity was found in eleven shoulders and grade-II laxity, in two.
The strength of the shoulder in elevation and internal rotation with the arm at the side was evaluated clinically on a scale of 0 (no strength) to 5 points (normal strength). Preoperatively, the strength of the involved shoulder was graded as good (4 points) in five patients, fair (3 points) in six, and poor (2 points) in two. The strength of the uninvolved shoulder was graded as normal (5 points) in five patients, good (4 points) in six, and fair (3 points) in two. Ten shoulders were graded as causing the patient difficulty, or a more severe disability, with the performance of at least ten of the fifteen activities of daily living listed on a standard evaluation form proposed by the American Shoulder and Elbow Surgeons30. The function of the remaining three shoulders was graded as mildly compromised with regard to the performance of at least ten of these activities.
Anteroposterior, axillary lateral, modified (so-called West Point26) axillary lateral, and Stryker notch14,25 radiographs were made for all patients. A posterolateral defect of the humeral head (a Hill-Sachs lesion) was observed in five shoulders; anterior glenohumeral subluxation, in three; and calcification along the anteroinferior aspect of the glenoid, in one. In addition, five shoulders that had had previous operations had degenerative changes, which were characterized by a decrease in the glenohumeral joint space, subtle flattening of the humeral head, and subchondral sclerosis or formation of cysts beneath the articular surface of the humeral head or the glenoid. Magnetic resonance images revealed a rupture of the subscapularis muscle and dislocation of the long head of the biceps tendon in one shoulder.
Eleven patients returned for clinical evaluation, and the other two were examined by the referring physician. The patients were assessed with use of a standardized evaluation form proposed by the American Shoulder and Elbow Surgeons30 as well as a modification of the grading system of Neer and Foster21. The result was satisfactory when there was no recurrence of anterior glenohumeral dislocation, no pain or only slight discomfort with performance of the activities of daily living and work, strength within one grade of the strength of the contralateral shoulder on manual testing, a range of motion within 10 degrees of the elevation and 40 degrees of the rotation of the contralateral shoulder, and normal function for at least ten of the fifteen activities listed on the American Shoulder and Elbow Surgeons evaluation form30. The result was unsatisfactory when these criteria were not met.
Operative Technique
The operative technique has been described in part previously25,30. The anterior axillary incision begins in the anterior axillary crease, extending proximally toward and usually stopping at the coracoid process. The skin is undermined subcutaneously in the proximal-medial and distal-lateral corners, so as to expose the deltopectoral interval. Usually, this interval is identified by the cephalic vein, which may be absent or lying deep in the interval. The deltopectoral muscles are retracted out of the way, and the clavipectoral fascia is divided vertically along the lateral border of the conjoined tendon of the pectoralis minor, the short head of the biceps, and the coracobrachialis muscles. The location of the musculocutaneous nerve as it enters the conjoined tendon is identified, and a Richardson retractor then is placed in the medial side of the incision to retract the conjoined muscles and the pectoralis major muscle. In shoulders that have not been operated on previously, the entrance of this nerve usually can be felt by palpating just medial to the conjoined tendon and muscles. Next, the axillary nerve is carefully identified and is protected with a Scofield retractor. When the shoulder has been operated on previously, this step can be very difficult because of extensive scarring and distorted anatomical landmarks.
With the musculocutaneous nerve identified and the axillary nerve protected with a retractor, the capsule is divided vertically, midway between its attachment on the glenoid rim and the humeral head. This incision begins at the superior glenohumeral ligament and extends all the way down to the most inferior aspect of the capsule. The joint is carefully explored for loose bodies, labral tears, chondromalacia, and other intra-articular abnormalities. Close attention should be paid to stripping of the labrum, capsule, and periosteum off their normal attachments on the glenoid rim and the neck of the scapula, as this may occur with recurrent anterior glenohumeral subluxation or dislocation.
If the capsule is securely fixed to the glenoid rim, capsular imbrication is performed30. However, if stripping of the capsule and the periosteum off the glenoid rim and the neck of the scapula has caused a defect of more than five millimeters, the capsule must be reattached before it is reconstructed. The capsular reconstruction is performed by so-called double-breasting of the medial aspect of the capsule laterally and superiorly under the lateral aspect of the capsule, as we find it technically easier to tie the sutures laterally, where exposure is optimum. The sutures are placed with the arm in 20 to 25 degrees of external rotation and abduction. Next, the lateral aspect of the capsule is double-breasted by taking it medially and superiorly and suturing it down to the anterior surface of the medial aspect of the capsule.
After completion of the capsular imbrication, the pectoralis muscle is transferred to substitute for the function of the subscapularis. In the present study, the pectoralis major was transferred in seven shoulders; the pectoralis minor, in five; and both muscles, in one. The pectoralis minor was transferred in the first five shoulders. Both pectoralis muscles were transferred in the sixth shoulder because the pectoralis minor was thought to be unusually small. The ease with which the pectoralis major muscle was transferred in that patient and the larger size of the musculotendinous unit obtained with this muscle prompted us to reconstruct the remaining seven shoulders with transfer of only the pectoralis major muscle.
Transfer of the Pectoralis Major
The pectoralis major is a large triangular muscle consisting of three portions. The origin of the superior, or clavicular portion, is at approximately the medial third of the clavicle, and the point of insertion is along the lateral lip of the bicipital groove. The middle, or sternal, portion originates from the manubrium, the superior two-thirds of the body of the sternum, and the second, third, and fourth ribs. It inserts along the lateral lip of the bicipital groove directly behind the clavicular portion, with a parallel fiber arrangement that is similar to the arrangement in that portion. The origin of the inferior, or sternocostal portion, of the pectoralis major is at the distal end of the body of the sternum, the fifth and sixth ribs, and the aponeurosis of the external oblique muscle. The tendon of the inferior portion of the muscle passes upward behind the superior two portions of the muscle, but the fibers rotate 180 degrees so that the inferior fibers insert superiorly on the humerus. Thus, the tendon has two laminae, anterior and posterior, which are usually continuous inferiorly. The posterior lamina usually inserts more superiorly on the humerus and may give rise to an expansion that covers the bicipital groove. The tendon complex is broad and flat, with a width of approximately five centimeters.
The superior 2.5 to three centimeters of the pectoralis major tendon, containing portions of both the anterior and the posterior lamina, is identified and is released from its insertion on the crest of the greater tubercle of the humerus (Fig. 1). Three or four stay sutures of one-millimeter Cottony Dacron (Deknatel, Fall River, Massachusetts) are placed in the lateral edge of the released tendon; these are used initially for traction on the tendon, in order to facilitate blunt dissection of the muscle medially for eight to ten centimeters, and later at the time of the reattachment of the tendon. The tendon must be freed enough so that it can be transferred easily across the bicipital groove to the distal half of the greater tuberosity.
The proximal part of the humerus is rotated internally, and an osteotome or an air burr is used to make a bone trough, five millimeters wide by twenty-five millimeters long, lateral to the bicipital groove in the distal half of the greater tuberosity. The trough must be lateral enough to the bicipital groove so that the tendon will be under tension when it is stabilized in the bone. Next, three or four holes are made, approximately five to seven millimeters lateral to the lateral edge of the bone trough, with use of a drill or an air burr. A curved awl and a tenaculum are used to create bone tunnels that connect the drill-holes to the bone trough (Fig. 2). The Dacron sutures in the tendon then are passed into the trough and out through the drill-holes (Fig. 3). When tension is placed on the sutures, the tendon is pulled down into the bone trough. The sutures are tied, thus securing the pectoralis major tendon into the bone trough (Fig. 4).
Transfer of the Pectoralis Minor
The tendon of the pectoralis minor is identified at its site of insertion on the coracoid process (Fig. 5). To obtain additional length of the muscle-tendon unit, the coracoacromial ligament is included with the tendinous insertion of the muscle. An osteotome is used to detach the coracoacromial ligament from the acromion and the superior cortical portion of the coracoid with the attached pectoralis minor tendon. This provides as much as two centimeters of length. As described for the pectoralis major tendon, the pectoralis minor tendon then is transferred across the bicipital groove and is secured into a bone trough in the distal half of the greater tuberosity (Fig. 6).
Postoperative Care
On the first postoperative day, the patient is instructed about gentle pendulum exercises and how to use the contralateral upper extremity for passive flexion exercises of the treated shoulder. Passive flexion exercises are permitted to an elevation of 90 degrees in sets of five repetitions and at a frequency of four, five, or six times a day. A shoulder immobilizer is worn for the first two weeks except when the patient is performing exercises or is at home and thus safe from injury. In conjunction with the program of rehabilitation for the shoulder, the patient is encouraged to exercise the elbow, wrist, and hand several times a day. At two weeks, the sutures are removed, the use of the sling is discontinued, and the patient is allowed progressive use of the upper extremity for activities of daily living. When the patient has a functional range of motion, approximately six to eight weeks after the operation, a formal strengthening program is begun.
The mean duration of follow-up was five years (range, two to eleven years). On the basis of the modified grading system of Neer and Foster21 and the evaluation form developed by the American Shoulder and Elbow Surgeons30, the result was satisfactory for ten shoulders and unsatisfactory for three. All of the shoulders for which the result was unsatisfactory had had at least two previous reconstructive operations.
Satisfactory Results
The ten shoulders with a satisfactory result had a mean postoperative range of motion of 143 degrees (range, 120 to 170 degrees) of elevation, 43 degrees (range, 30 to 70 degrees) of external rotation, and internal rotation to the spinous process of the eighth thoracic vertebra (range, the third lumbar to the sixth thoracic vertebra).
Postoperatively, the strength of seven shoulders was graded as good and the strength of three was fair. Anterior glenohumeral laxity with the arm in neutral rotation was grade II in all ten shoulders. With the arm externally rotated 30 degrees, anterior laxity was classified as grade I in eight shoulders and grade II in two. The lift-off test, as described by Gerber and Krushell12, was performed by three patients. An abnormal finding on this test, which suggests rupture of the subscapularis tendon, is characterized by the inability to lift the dorsum of the hand off the back when the arm is fully extended and internally rotated. The finding on the test was normal for two shoulders in which the 0pectoralis major had been transferred (Figs. 7-A 7-B 7-C 7-D) and was abnormal for one shoulder in which the pectoralis minor had been transferred.
None of the patients who had a satisfactory result reported additional episodes of dislocation, and all of them had less apprehension with abduction and external rotation of the involved extremity on physical examination. All ten patients had slight or no pain with performance of the activities of daily living and work. Seven patients had a job that was not physically demanding (computer consultant, physician, pharmacist, homemaker, day-care worker, or accountant), and three had a physically demanding job (ranch-hand or heavy-equipment operator).
All patients reported normal function for at least ten of the activities of daily living listed on the American Shoulder and Elbow Surgeons evaluation form30.
Unsatisfactory Results
The three shoulders with an unsatisfactory result had a mean postoperative range of motion of 110 degrees (range, 60 to 140 degrees) of elevation, 80 degrees (range, 70 to 90 degrees) of external rotation, and internal rotation to the spinous process of the second lumbar vertebra (range, the third to the first lumbar vertebra). Postoperatively, all three shoulders had poor strength. With the arm in neutral rotation, anterior glenohumeral laxity was grade II in one shoulder and grade III in two. No differences were found in the degree of laxity when the shoulders were tested again with the arm in 30 degrees of external rotation. The lift-off test was performed by one patient in whom the pectoralis minor had been transferred; the finding of the test was abnormal.
Two patients had recurrent anterior dislocation of the shoulder associated with pain and subjective numbness or tingling in the involved extremity. These dysesthesias were not in any particular dermatomal distribution, but they were characterized by a sudden sharp or disabling pain at the time of the recurrent dislocation and were often associated with transient weakness and loss of control of the upper extremity. The episodes of dislocation characteristically involved minimally provocative activities such as throwing a ball, swinging a tennis racquet, or diving into a pool. Although both patients learned various manipulative techniques that allowed them to reduce the shoulder themselves, they sometimes needed help to effect the reduction.
Two patients had activity-related pain, and one had moderate discomfort with most activities, including work and activities of daily living. None of the patients could use the shoulder for overhead activities of daily living, work, or sports because of discomfort or apprehension.
Each of the three patients had had at least two previous reconstructive procedures of the shoulder. One patient, a twenty-seven-year-old corrections officer, had had five previous reconstructions. The operative findings included adhesions of the brachial plexus, which were treated with neurolysis, and early degenerative changes of the anterior aspect of the glenoid and the humeral head. Twenty-five months after transfer of the pectoralis major, the shoulder was reinjured in a motor-vehicle accident. Physical examination at that time demonstrated 90 degrees of external rotation and a positive apprehension test. At the five-year follow-up examination, the patient reported discomfort with activities of daily living and work. These symptoms were associated with radiographic evidence of progressive degenerative joint disease and necessitated the use of anti-inflammatory medication. The patient needed vocational rehabilitation.
The second patient was a seventy-seven-year-old woman who had had four previous reconstructions of the shoulder. At the time of the transfer of the pectoralis major, degenerative changes of the glenohumeral joint were found. The patient did well initially but dislocation recurred after the shoulder was reinjured in a fall five months postoperatively. At the two-year follow-up evaluation, the patient described slight discomfort and a slipping sensation that occurred approximately twice a month. She had minor difficulty with some household tasks, but this did not preclude the performance of these activities. Interval radiographs demonstrated progressive degenerative changes and narrowing of the glenohumeral joint space. At the six-year follow-up examination, the patient reported discomfort with activity and barometric changes, which necessitated the use of non-steroidal anti-inflammatory medication.
The third patient who had an unsatisfactory result was a thirty-seven-year-old bank teller who had had the index procedure because of symptomatic dislocation after a Putti-Platt reconstruction and a Bristow procedure. This patient did well for five years after transfer of the pectoralis minor, with no additional episodes of dislocation until the shoulder was reinjured in a fall. After the injury, she was managed with a shoulder-strengthening program and did not want additional operative treatment.
Several investigators have described avulsion of the subscapularis tendon associated with recurrent subluxation or dislocation of the shoulder. Hauser15 reported on two patients, both of whom had improvement after isolated repair of the injury. In a study by Neviaser et al.22, anterior subluxation or dislocation of the shoulder recurred after rupture of the subscapularis tendon and the underlying anterior part of the capsule. Reattachment of the subscapularis tendon and the anterior portion of the capsule to the lesser tuberosity was successful in restoring stability in all shoulders. All of the patients, except one, were more than forty years old. None of the patients in either study15,22 had had previous operative treatment for the ruptured subscapularis or for the dislocation. In contrast to the findings in those studies, the detachment of the subscapularis was not reparable in any of our patients, despite considerable effort to identify and mobilize that structure. Moreover, ten patients in the present study had had previous operative treatment and seven patients were less than forty years old.
Although there was no direct evidence in the present study to confirm that the rupture of the subscapularis contributed to anterior subluxation or dislocation of the shoulder, our belief that it did has been well supported in the literature. Laxity of the subscapularis muscle, decreased muscle tone, and rupture of the tendon have been found by several authors at the time of the operative treatment of recurrent dislocation of the shoulder6,15,16,18,20. McLaughlin18, DePalma and Silverstein6, Eden10, and Jens16 all reported that, at the time of the operation but before arthrotomy, the humeral head became dislocated under the inferior edge of the subscapularis tendon when the shoulder was abducted and externally rotated. In several of these shoulders, there was a definite defect along the anterior or inferior aspect of the subscapularis tendon, as if it had been partially torn from its insertion on the proximal part of the humerus. The reports in the literature, as well as our experience, caused us to be concerned that the glenohumeral ligaments would eventually fail to provide long-lasting restraint against anterior glenohumeral subluxation and dislocation if repair of the tendon was not coupled with the re-establishment of a dynamic muscle structure to replace the function of the subscapularis.
Young and one of us (C.A.R., Jr.)31 reported on the treatment of complications that occurred after a failed Bristow procedure in thirty-nine patients. Fifteen were managed with a revision operation, and seven of these revisions were described as being unusually complicated because of severe thinning and fraying of the subscapularis tendon, erosion of the anterior part of the glenoid, or posterior subluxation. In order to reinforce the attenuated subscapularis, the pectoralis minor was transferred in four patients and the pectoralis major, in one. In that study31, the result was good or excellent in four of five patients who were evaluated with a modification of the rating scale of Rowe et al. Although the subscapularis was not completely detached in those patients, we were encouraged by the early results of transfer of the pectoralis muscle and began performing that procedure in patients who had a complete loss of the subscapularis muscle.
Moeckel et al.19 reported that anterior subluxation or dislocation of the shoulder occurred in seven patients after joint replacement. Operative exploration revealed a disruption of the subscapularis tendon in all shoulders, and primary reconstruction of the avulsed subscapularis corrected the anterior instability in four of them. Anterior glenohumeral subluxation or dislocation recurred in the remaining three shoulders; at the time of the second operative reconstruction, the subscapularis tendon and the capsule could not be reconstructed because of scarring and shortening. A static stabilizer, consisting of a bone-Achilles tendon allograft, was used successfully for the reconstruction of the three shoulders. The shoulders in the present study were similar to those three shoulders, in that the disruption of the subscapularis tendon was irreparable. In contrast to the allograft reconstructions described by Moeckel et al.19, the reconstructions in the present study included transfer of a muscle. Such a reconstruction can be advantageous because it obviates the need for a static stabilizer such as an allograft and it avoids the complications associated with a so-called bone block that is employed as an anterior buttress or to extend the area of the articular surface of the glenoid.
In the report by Young and one of us31, severe degenerative changes of the glenohumeral joint were found after a failed Bristow procedure in ten of the twenty-four patients in whom the condition of the articular cartilage was assessed. It is particularly noteworthy that the defects in the humeral-head articular cartilage were thought to be related directly to injury from the screw that had been used to secure the transferred tip of the coracoid process. We believe that the Bristow procedure and other techniques involving a bone block are contraindicated when the subscapularis muscle is completely detached, as such procedures involve an unnecessary risk of injury of the humeral-head articular cartilage.
Gerber and Krushell12, in 1991, described a clinical maneuver, termed the lift-off test, that they had designed to identify weakness of internal rotation in patients who have a ruptured subscapularis tendon. The test is performed with the arm fully extended and internally rotated and is based on the premise that weakness of internal rotation is most easily demonstrated at the limit of the amplitude of contraction of the muscle. As reported by those authors12, the result of the lift-off test is abnormal when the patient is unable to lift the dorsum of the hand off the back. More recently, Gerber et al.13 reported that use of the lift-off test substantially improved the accuracy of the diagnosis of a tear of the subscapularis tendon preoperatively, but a normal or abnormal result on the test at the follow-up examination did not have a direct association with the clinical outcome. Although we currently employ this maneuver to identify weakness of internal rotation when we suspect an injury of the rotator cuff, we did not use it routinely in the present investigation because we were not aware of it during most of the study period. It is interesting to note that the result of the lift-off test was normal after the operation in two of the four shoulders that were examined more recently. In both shoulders, the pectoralis major had been transferred.
Operative reconstruction of the unstable glenohumeral joint is considered when symptomatic subluxation and dislocation repeatedly cause discomfort or impair the function of the shoulder despite a rehabilitation program designed to strengthen the three parts of the deltoid, the internal and external rotators of the shoulder, and the scapula-stabilizing muscles. When an operative approach for recurrent anterior glenohumeral subluxation and dislocation is considered, it is essential to identify any factors that may affect the operative results, such as severe osseous defects of the humeral head, intrinsic capsular damage, or injury to the rotator cuff muscles.
The first five patients in the present study were treated with a modification of the procedure that Dickson and O'Dell8 described in 1952. Those authors advocated transfer of the pectoralis minor from its coracoid insertion to the greater tuberosity of the humerus in an effort to buttress the anterior structures of the shoulder and to counterbalance the external rotators of the glenohumeral joint in patients who had anterior subluxation or dislocation of the shoulder. Dickson and O'Dell8 credited their concept to phylogenetic studies that demonstrated insertion of the pectoralis minor tendon on the greater tuberosity of the humerus, where it exerted an action of internal rotation on the limb.
Of the remaining shoulders in the present series, one was reconstructed with both pectoralis muscles and seven were reconstructed by transfer of the superior portion of the pectoralis major tendon. Transfer of the superior two to three centimeters of the tendon, which includes portions of both the anterior and the posterior lamina, is now preferred over transfer of the pectoralis minor tendon for several reasons. First, obtaining an adequate length of the muscle-tendon unit is easier because of greater excursion of the muscle. Second, the larger cross-sectional area and bulk effect of the muscle provide a more effective checkrein during abduction and external rotation of the arm. Third, the larger muscle has a dampening effect during active motion. Turkel et al.28 investigated a similar stabilizing mechanism of the glenohumeral joint by anatomical dissection of the subscapularis and glenohumeral ligaments in cadavera. Those authors found that the subscapularis muscle stabilizes the shoulder, in terms of anterior and inferior displacement, in the lower range of abduction (45 degrees or less).
To the best of our knowledge, we are the first to report on transfer of the pectoralis muscle in patients who had recurrent anterior glenohumeral subluxation or dislocation and an irreparable rupture of the subscapularis muscle. In our study, active contraction of the transferred pectoralis major muscle and diminished anterior glenohumeral translation with the arm in external rotation was demonstrated in all ten shoulders for which the result was satisfactory. We believe that increased glenohumeral stability in that position results from a checkrein effect of the transferred muscle-tendon unit, similar to that found after a Magnuson-Stack procedure, in which the subscapularis tendon is transferred in a lateral direction, from the lesser tuberosity to the greater tuberosity.