Posterior Glenohumeral Instability Treatment & Management
- Author: John P Salvo, Jr, MD, MS; Chief Editor: S Ashfaq Hasan, MD more...
The primary indication for surgery for posterior glenohumeral instability is recurrent symptomatic shoulder subluxation or dislocation that is recalcitrant to conservative measures. Surgical treatment should be considered only in patients who remain significantly disabled after an adequate trial involving strengthening exercise and avoidance of provocative positions.
Burkhead and Rockwood stressed that 80% of patients with an atraumatic cause of shoulder instability, in contrast to 16% of those with traumatic instability, improve with an exercise program alone. Others reported that 70% of athletes subjectively improve with a conservative program.[43, 15] The instability, however, is usually not eliminated, but the functional disability during athletics is improved, allowing the patient to participate in his or her sport without problems.
All patients who subluxate voluntarily should undergo the appropriate psychological evaluation before operative treatment is recommended. Patients with positional instability in which the humeral head subluxes posteriorly when the arm is adducted at 90° of flexion have a good response to surgical intervention.[22, 24, 60] Surgical intervention is associated with a 50-95% success rate.[45, 46, 47]
Children with posterior shoulder instability secondary to neonatal brachial plexus injury fall into two general categories: early and late. In children in whom the diagnosis is established early (usually before age 2 years), reconstructive and tendon-balancing procedures are options.[50, 51] In many children who present late with established dislocations, rotational osteotomy of the proximal humerus (with or without additional soft-tissue procedures) can significantly improve shoulder function.[52, 61]
Specific contraindications to the surgical treatment of posterior shoulder instability include situations in which conservative treatment, including activity modification and a formal exercise program, has not been attempted. The length of a trial of conservative treatment before surgery varies, but Tibone and Bradley recommended continuing an exercise protocol for at least 6 months before resorting to surgical treatment. Many patients become asymptomatic in terms of pain and function after completing a physical therapy protocol, though clinically, the instability may persist.
Patients with voluntary instability of the shoulder who have a psychological disorder or who are seeking secondary gain are not candidates for surgical reconstruction. Any patient in whom voluntary instability is suspected should be evaluated by a mental health specialist to screen for underlying psychological conditions.
Nonoperative treatment for acute posterior shoulder dislocations involves an attempt at closed reduction. After muscle relaxation is achieved, traction is established in an adducted position, in line with the deformity, with the patient supine. The humeral head is gently lifted into the glenoid fossa. Forced external rotation is avoided because a head locked on the glenoid rim may lead to fracture of the humeral head or shaft. Lateral traction may be combined with longitudinal traction with a soft towel or sheet.
The shoulder is immobilized for 6 weeks in 20° of external rotation; an exercise program follows, designed to achieve a painless range of motion, a normal scapulohumeral rhythm, and strengthening of the dynamic restraints.
Fixed posterior dislocations are rarely treated nonoperatively. Nonoperative treatment is reserved for patients who are inactive or poor surgical risks. In this situation, a reasonable goal is to provide the patient with a painless compensatory range of motion to perform the activities of daily living.
All patients with posterior shoulder subluxation should undergo a trial of nonoperative care before surgery is considered. An exercise program that develops a pain-free range of motion, a normal scapulohumeral rhythm, and strengthening of the dynamic restraints is recommended.
Burkhead and Rockwood evaluated the efficacy of specific muscle strengthening exercises to treat anterior, posterior, and multidirectional instability. The two-phase exercise program, which the patients performed at home, provided progressive resistance training of the rotator cuff muscles and deltoid. Only 15% of patients with a traumatic etiology for their instability had good or excellent results. This was compared with 83% good or excellent results in patients with an atraumatic etiology for their instability.
Engle and Canner suggested a more comprehensive three-phase program relying on manual proprioceptive neuromuscular facilitation (PNF) and multiple changes of training types (from progressive resistance exercises to isokinetics, isometrics, concentric loading, and eccentric loading). The rigorousness of this program mandates constant monitoring by a physical therapist.
An exercise program typically is continued for at least 6 months in an attempt to strengthen the shoulder musculature and decrease any functional disability. Seventy percent of athletes in Tibone and Bradley's study subjectively improved with a conservative program. The instability, however, is usually not eliminated by an exercise program, but the functional disability during athletics is improved, allowing the patient to participate in his or her sport without problems. Athletes who respond to conservative care are usually satisfied, can tolerate their instability, and need no further treatment.
Surgical Therapy for Posterior Dislocations
Surgery for a posterior shoulder dislocation can be difficult, particularly for a joint that has not been reduced for some time or has extensive damage to the humeral head or glenoid. Hawkins et al established guidelines for the management of posterior dislocations on the basis of how long the shoulder has been dislocated and what percentage of the humeral head has been involved with the articular surface defect (reverse Hill-Sachs defect).
Closed reduction is recommended if the dislocation was within the previous 6 weeks and if, on axillary radiography, the articular defect involves less than 20% of the articular surface. If the arm is stable, it is immobilized in 20° of external rotation for 6 weeks. If it is unstable, the Neer modification of the McLaughlin procedure (see below) is recommended, followed by immobilization. For dislocations present for 6 weeks to 6 months and involving 20-45% of the articular surface, either a McLaughlin procedure or the Neer modification is recommended, again followed by immobilization in external rotation. With a normal glenoid and greater than 45% humeral head involvement in a dislocation that occurred more than 6 months earlier, hemiarthroplasty is recommended.
Surgical Therapy for Locked Posterior Dislocations
Subscapularis transfer (McLaughlin procedure)
In 1952, McLaughlin described the technique of subscapularis transfer from the lesser tuberosity into the anterior articular defect (Hill-Sachs defect) for locked posterior dislocation or recurrent posterior instability. McLaughlin reported good to excellent results in three of three locked posterior dislocations and two of two recurrent subluxations. Hawkins et al reported good to excellent results in four patients treated with this technique who had articular defects of 20-45% of the humeral head; five patients referred to them with failures of this procedure had articular defects of greater than 45%.
Lesser tuberosity transfer (Neer modification of McLaughlin procedure)
Working from the theory that bone heals to bone better than to tendon, Neer modified McLaughlin's technique by transferring the subscapularis tendon with its lesser tuberosity insertion into the humeral head defect and securing it with screws. Four of four patients in Neer's study had good or excellent results.
Allograft reconstruction of humeral head defect
Gerber described a technique of allograft reconstruction of segmental defects of the humeral head for chronic locked posterior dislocations. An allograft femoral head with articular surface was contoured to the shape of the humeral head defect and secured with screws. Four patients with defects of at least 40% were treated with this technique. Three of the four reported little or no pain; one, after being symptom-free for 6 years, experienced severe dysfunction secondary to avascular necrosis of the remaining portion of the humeral head.
With a normal glenoid and greater than 45% humeral head involvement, hemiarthroplasty is recommended for a dislocation that has been present for more than 6 months. Total shoulder arthroplasty is recommended when the glenoid is significantly involved (see the image below). A bone graft from the involved humeral head can be used for glenoid bone loss. The normal humeral head retroversion of 30-40° may predispose a prosthesis to further instability. Therefore, a compensatory relative anteversion should be used during insertion of the humeral component.
Hawkins recommended neutral version for a shoulder that has been dislocated for longer than 6 months and approximately 20° of retroversion for a dislocation that has occurred within the previous 6 months.
Pritchett reported that of seven patients treated with arthroplasty for anterior or posterior chronic dislocation, all improved over their preoperative status, with five good results and two fair results.
Cheng reported that total shoulder arthroplasty for locked posterior dislocations reliably decreased the patient's level of pain, improved range of motion, and significantly improved level of function. Use of a secondary posterior incision facilitating the extrication of the humeral head also was described.
Surgical Therapy for Chronic Posterior Instability
Because of the infrequent nature of recurrent posterior subluxation and the variable results of surgical intervention, many small series have been reported, each employing a different treatment technique. In patients refractory to conservative measures, surgical treatment may be considered. Surgical treatment for posterior instability has historically included the following procedures:
Biceps tendon transfer with staple capsulorrhaphy
Reverse Bankart repair
Reverse Putti-Platt repair
Posterior/inferior capsular shift
Posterior bone block
Posterior staple capsulorrhaphy
Various combinations of the above
Reverse Bankart procedure
Rowe and Yee described the reverse Bankart procedure in two patients, using drill holes placed through the glenoid rim to the medial bone and then securing the capsular flap with mattress sutures. In both of the cases described, the patient regained normal function.
Reverse Putti-Platt repair
The reverse Putti-Platt procedure was originally described by Severin, who shortened the infraspinatus only, and DePalma, who shortened the infraspinatus and the teres minor together. A subsequent report on this procedure stated that 16 out of 17 patients had excellent results and no recurrent subluxation or dislocation.
Biceps tendon transfer with staple capsulorrhaphy
Boyd and Sisk described the use of a biceps tendon transfer in conjunction with posterior capsulorrhaphy for recurrent dislocations of traumatic origin or voluntary subluxations that become involuntary. In the biceps tendon transfer, the long head of the biceps was placed posteriorly, secured to the glenoid rim with the capsule by a staple.
Opening wedge osteotomy
In 1967, Scott first described the use of an opening wedge osteotomy to correct excessive glenoid retroversion. A broad osteotome was used to perform the medially directed osteotomy from the supraglenoid tubercle to the origin of the long head of the triceps. The glenoid neck was then wedged open with a portion of the removed acromion. Brewer et al reported good or excellent results in five of five patients and recommended iliac crest bone graft instead of bone graft with an osteotomized piece of acromion.
Complications following this technique include recurrence of instability, osteoarthritis, avascular necrosis secondary to joint penetration, and coracoid impingement. Bone block procedures to the posterior glenoid have been shown to act as a buttress against posterior subluxation.[70, 71]
Autologous iliac crest graft
The use of an autologous iliac crest graft from the posterior superior iliac spine was first described in 1949 by Fried, who reported recurrence of instability, attributed to resorption of the bone graft, in one of five patients. Some authors have advocated the use of a posterior bone block in combination with another procedure. A variation of the open wedge glenoid osteotomy—using a vascularized bone graft taken from the scapular spine with its adjacent posterior deltoid pedicle—was described by Cziffer et al. The authors used this procedure for revision instability repair when posterior glenoid deficiency or retroversion greater than 30° was present.
Rotational osteotomy of humerus
Variations in the version of both the humerus and glenoid have been theorized as disposing factors in glenohumeral instability. Chaudhuri described a rotational osteotomy of the humerus whereby the humeral shaft is externally rotated in recurrent posterior dislocations. Reported complications following this procedure have included recurrence of instability and pseudoarthrosis of the humeral osteotomy site. Surin reported good or excellent results in 10 of 12 patients with posterior instability. Rotational osteotomy of the humerus has also been described for locked posterior dislocations of the shoulder.
Chronic posterior instability lesions
Typical lesions in chronic posterior instability include posterior labral fraying and tears, a patulous capsule, and, rarely, osteoarthritis of the glenohumeral joint. (See the image below.)
Interestingly, reverse Bankart lesions are extremely rare in patients who have true posterior subluxation without a prior history of a significant isolated traumatic episode causing a posterior dislocation. Because posterior instability appears to be a capsular problem, procedures have been designed that specifically address this problem (see the images below).
Posterior capsulorrhaphy with suture fixation is currently the open procedure of choice. In the past, this treatment was performed with staple fixation; however, staples have been found to cause metal complications about the shoulder and are no longer recommended. Posterior capsular shift procedures have been described by several surgeons, including Neer, Rockwood, and Warren.
Neer's technique begins with a vertical skin incision and blunt dissection through the deltoid. The infraspinatus tendon is divided obliquely so that the superficial portion can be attached to the scapula to reinforce the posterior portion of the capsule. A horizontal capsular incision is made lateral to the tuberosity, with further extension for additional inferior laxity.
A T-shaped opening is made in the posterior capsule at the humeral side to form a superior flap and an inferior flap. The inferior flap is completed by detachment of the capsule from the neck of the humerus to its inferior aspect. During this step, the arm is kept internally rotated. The axillary nerve is carefully protected by using a Darrach retractor and by leaving the teres minor intact.
The arm is positioned in 20-40° of external rotation. The humeral neck is decorticated with a curette or burr. The superior flap is pulled downward and reattached. The inferior flap is then pulled backward and upward over the secured superior flap, thus reducing the redundancy of the capsule anteriorly, inferiorly, and posteriorly. If significant inferior instability exists, the inferior flap is advanced first in a pants-over-vest fashion. The capsular flaps are reinforced with the superficial part of the infraspinatus tendon and brought down and sutured against raw bone on the scapular neck. The deep portion of the infraspinatus tendon is sutured over this so that it will remain a strong external rotator.
Bigliani et al reported good or excellent results in 28 of 35 shoulders treated with this technique. Four shoulders became unstable; in six of the seven shoulders in which unsatisfactory results were recorded, previous stabilization attempts had been made.
Fuchs et al reported on 26 shoulders treated with this technique and found that it produced 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.
Rockwood's technique also begins with a vertical skin incision, blunt dissection through the deltoid, and a vertical incision through the infraspinatus tendon, which is reflected medially. If the muscle is particularly lax, the interval between the infraspinatus and the teres minor is split. A vertical capsular incision is made midway between the humerus and glenoid and extended inferiorly to address laxity. This creates a medial- and lateral-based flap. The arm is placed in neutral rotation. In a pants-over-vest fashion, the medial flap is advanced superiorly and laterally under the lateral flap. The overlying lateral flap is advanced superiorly and medially over the medial repair.
Fronek et al described a technique of posterior capsulorrhaphy with or without a bone block for posterior subluxation. A horizontal or vertical skin incision is made, and the infraspinatus is divided with a vertical incision and reflected medially. A vertical capsular incision is made near the glenoid margin with a T-horizontal incision from the middle of the glenoid to the humerus. Alternatively, to address excessive inferior laxity, an additional horizontal incision is made at the humeral border of the capsule, creating an H-shaped incision.
The inferior flap is advanced medially and superiorly and repaired to the medial glenoid to address inferior laxity. The superior flap is then pulled downward and used to reinforce the inferior flap. If a loose labrum is present, drill holes are placed into the underlying bone. The labrum is sutured to the bone and the capsule advanced. If needed, a bone graft can be used as well.
In the study by Fronek et al, 11 patients were treated operatively, with a 91% success rate. Sixteen patients in the study were treated conservatively with physical therapy, with a success rate of 63%.
Knowledge has been expanding regarding the significant role of the coracohumeral and superior glenohumeral ligaments in posterior instability. Several authors have adopted an anterior surgical approach to correct posterior instability. Nobuhara and Ikeda performed rotator interval reconstructions in patients with posteroinferior instability. Of the 78 patients evaluated, they reported 96% good or excellent results, with recurrent instability reported in 4% of cases (three patients).
Brems reported excellent results in 86% of patients after a posterior inferior capsular shift that was performed through an anterior approach; this technique was used to treat posterior instability in shoulders that had not previously undergone surgery. However, Brems reported poor results in 86% of patients after performing the same technique on shoulders that had undergone previous posterior reconstructive procedures.
Wirth et al described a capsulorrhaphy through an anterior approach for the treatment of a traumatic posterior glenohumeral instability with multidirectional laxity of the shoulder. The procedure involved closure of the capsule in the rotator interval and imbrication of the capsule's anterior, inferior, and posteroinferior aspects with a double-breasting technique that decreased the overall capsular volume. Of the 10 patients treated, nine had good or excellent results.
Subsequent advances in arthroscopic technique have led to the development of procedures to address posterior glenohumeral instability. The use of a biodegradable Suretac device has been described. McIntye et al reported the 2-year results on a multiple-suture technique for posterior instability. Their technique involved a capsular repair of the posterior band by sutures tied into the inferior capsule and then brought up to the superior portal and tied over the fascia of the trapezius or bone. They reported 17 good or excellent results and four fair or poor results. Two recurrent dislocations and three subluxations occurred, for an overall recurrence rate of 25%.
Wolf reported on 14 patients (minimum follow-up, 2 years) who underwent posterior capsular plication with or without suture anchors. Twelve patients had excellent results, and two had fair results.
Antoniou reported a large study of 41 patients who were treated with an arthroscopic capsular shift of the posteroinferior aspect of the capsule to the adjacent labrum and were monitored for a minimum of 12 months. The mean score on the simple shoulder test improved statistically, as did two of the eight Short-Form 36 (SF-36) parameters. Thirty-five patients had improved stability, and 28 had a perception of residual stiffness.
Bradley et al reported a prospective review of 100 shoulders in 91 athletic patients. The patients were treated for unidirectional posterior glenohumeral instability with an arthroscopic capsulolabral plication, either alone or, in the event of a concomitant labral tear, with suture anchors. The researchers demonstrated an effective arthroscopic procedure with regard to stability, pain relief, and functional restoration in an athletic population.
In this study, subjective stability and pain scale scores improved significantly compared with preoperative values. Functional American Shoulder and Elbow Surgeons (ASES) scores improved significantly, with postoperative range-of-motion mean subjective scores within the satisfactory to full range of motion. Standardized ASES shoulder scale scores improved significantly with this procedure, with an overall 91% excellent or good result. Patients were able to return to the same competitive level in their respective sport 67% of the time, with 22% reporting a return to their sport at a limited level; 11% did not return to competition, because of their shoulder injury.
In another study of 200 shoulders in 183 athletes, Bradley et al reported greater improvement in patients when bone suture anchors were incorporated into capsulolabral reconstruction.
Detachment of the posterior glenoid labrum and capsule below the equator of the glenoid (ie, a posterior Bankart lesion) can be particularly debilitating for patients and challenging for caregivers to effectively manage. In a retrospective review by Williams et al, traumatic posterior Bankart lesions in 27 shoulders were arthroscopically treated with capsulolabral repair. At follow-up (mean, 5 years), no patient exhibited deficits in range of motion or any instability of humeral head translation beyond the glenoid rim (+1). Pain and instability were eliminated in 92% of patients. Two patients required further surgical intervention: One ultimately required an open capsulorrhaphy, the other a repeat arthroscopy for labral debridement.
Similarly, Kim et al presented an evaluation of their results of arthroscopic treatment of 27 patients with traumatic unidirectional recurrent posterior subluxation of the shoulder, at a mean follow-up of 39 months. All patients were treated with nonabsorbable sutures and/or suture anchors, with repair of labral lesions and a superior shift of the posterior capsule. All patients had improved shoulder function scores, and all but one patient had stable shoulders according to subjective and objective measurements.
One study retrospectively reviewed 31 shoulders treated for traumatic posterior shoulder instability; the report compared findings from open posterior stabilization (12 cases) and arthroscopic stabilization (19 cases) for a variety of shoulder outcome instruments. Follow-up averaged 40 months, and 29 of 31 shoulders rated as excellent or good following surgical intervention. Interestingly, significant differences were noted between the arthroscopic and open methods of fixation for instrument measurements for disability (Western Ontario Shoulder Instability Index [WOSI]) and function, stability, and range of motion (Rowe), with arthroscopic repair showing the more favorable results.
Results from other methods of evaluation, comparing subjective results (Single Assessment Numeric Evaluation [SANE]) and function with return to sport (Simple Shoulder Test [SST]), were not significantly different for the open and arthroscopic methods. However,the results of these instruments did favor the arthroscopic methods of fixation.
In a study of 56 American football players with unidirectional posterior shoulder instability, Arner et al found that arthroscopic posterior capsulolabral repair, with or without suture anchors, yielded excellent or good results in 96.5% of patients. Stability, pain, and joint function were all improved, thus increasing the likelihood of successful return to play.
Immobilization of the shoulder with some variation is recommended for approximately 6 weeks. Historically, the method of immobilization has involved use of a spica-type cast. Newer, prefabricated braces have been developed, including the gunslinger brace (see the image below) and the DonJoy UltraSling.
The key to postoperative bracing is the position in which the shoulder is held. As recommended in the literature, the degree of external rotation should be between neutral and 45°, and abduction should be between neutral and 90°. The common goal is to allow healing through relaxation of the posterior structures.
Complications associated with posterior glenohumeral instability surgery can be divided into early and late problems. Early problems include the following:
Recurrence of instability
Late complications include the following:
Recurrence of instability
Hardware protrusion into the joint
The most common complication following posterior stabilization surgery is recurrence of instability, with rates averaging 15-20%.[20, 56] Open and arthroscopic techniques used to treat posterior instability have both been associated with a high recurrence rate in comparison with similar open or arthroscopic treatment of anterior instability. The athlete may have a successful surgical outcome with the elimination of posterior instability, but as many as 50% of patients may not be able to reach their premorbid activity levels. Voluntary and willful shoulder instability leading to failure of operative intervention has certainly been problematic; the solution has been to try to recognize these situations before operative intervention.[22, 49]
Reasons for failure after posterior instability surgery can be categorized into four main groups, as follows :
Group 1 - Traumatic causes of failure, including major trauma and repetitive microtrauma.
Group 2 - Nonsurgical causes of misdiagnosis and patient selection errors; misdiagnosis errors may include missed multidirectional instability, incorrect assessment of instability direction, glenohumeral degenerative joint disease, impingement syndrome, cervical spine pathology, and acromioclavicular joint arthritis; selection errors include choosing patients with willful dislocations, problematic psychiatric history, poor motivation, or seizure disorder or selecting patients who are noncompliant with rehabilitation
Group 3 - Surgical errors, including uncorrected pathology, overtightening, bone block malposition, osteotomy error, and nerve injury
Group 4 - Rehabilitation errors
After immobilization, range-of-motion exercises are started. The patient is encouraged to actively move the shoulder. Passive and (particularly) active assisted motion is discouraged for fear of stretching the arm too far, thereby producing recurrent instability. The strengthening program typically is initiated after painless passive range of motion is achieved. The strengthening program used is identical to that employed for nonoperative strengthening, as previously described. Noncontact sports are allowed after 6 months. Contact sports with a brace are allowed after 12 months, with protection of the shoulder in a brace for an additional year.
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