You are in: eMedicine Specialties > Orthopedic Surgery > SHOULDER Anterior Glenohumeral InstabilityArticle Last Updated: Jul 7, 2004AUTHOR AND EDITOR INFORMATIONAuthor: Amin Afsari, DO, Staff Physician, Department of Orthopedic Surgery, Grandview Medical Center Amin Afsari is a member of the following medical societies: American Osteopathic Association Coauthor(s): Charles T Mehlman, DO, MPH, Director, Musculoskeletal Outcomes Research, Associate Professor, Division of Pediatric Orthopaedic Surgery, Cincinnati Children's Hospital Medical Center Editors: Cato T Laurencin, MD, PhD, University Professor, Lillian T Pratt Distinguished Professor and Chairman, Department of Orthopaedic Surgery, The University of Virginia; Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine; Pekka A Mooar, MD, Associate Professor, Department of Orthopedic Surgery, Temple University School of Medicine; Dinesh Patel, MD, FACS, Associate Clinical Professor of Orthopedic Surgery, Harvard Medical School; Chief of Arthroscopic Surgery, Department of Orthopedic Surgery, Massachusetts General Hospital; Mary Ann E Keenan, MD, Professor, Vice Chair for Graduate Medical Education, Department of Orthopedic Surgery, University of Pennsylvania School of Medicine; Chief of Neuro-Orthopedics Program, Department of Orthopedic Surgery, Hospital of the University of Pennsylvania Author and Editor Disclosure Synonyms and related keywords: anterior shoulder instability, shoulder laxity, recurrent dislocation, traumatic dislocation, Bankart lesion, shoulder pain, dislocated shoulder, shoulder dislocation, joint dislocation, recurrent anterior glenohumeral instability INTRODUCTIONThe shoulder is the most commonly dislocated joint in the body. When shoulder dislocation occurs in adolescents and children, it has the worst natural history of any injury; the rate of recurrence in later years is at least 70%. As many as 95% of shoulder dislocations are anterior. Anterior dislocations often lead to recurrent anterior glenohumeral instability. Recurrent anterior glenohumeral instability accounts for the largest portion of the shoulder laxity spectrum. Excessive deviation of the humeral head on the glenoid occurs in all or 1 of 3 directions: anterior, posterior, or inferior. Although certainly not life threatening, recurrent subluxation or dislocation is clearly lifestyle threatening and can effectively disable an otherwise active individual. Normal shoulders have a certain degree of laxity due to minimal bony restraint of the joint, which in turn allows the widest range of motion of any joint in the body. The result is a tremendous need for competent soft tissue balance and control. Traumatic damage leads to laxity in the soft tissue and bony restraints; thus, recurrent subluxation and dislocation ensues. Atraumatic etiologies also exist, but this article focuses on recurrent subluxation and dislocation due to trauma. Nonoperative and operative therapies both play a role in treatment of anterior shoulder instability. Both have been studied extensively. Surgical management has gone through an evolutionary process involving multiple methods of fixation. This evolution has led to operative fixation that achieves a stable repair with little restriction of motion. For excellent patient education resources, visit eMedicine's Breaks, Fractures, and Dislocations Center. Also, see eMedicine's patient education article, Shoulder Dislocation. History of the ProcedureReports of anterior glenohumeral instability and its many repair methods date back to Hippocrates' treatise, "On Joints." Hippocrates described the practice of using cautery to cause the capsule to scar and thus tighten around the joint. He wrote, "grasp the skin at the armpit between the fingers and draw it in the direction towards which the head of the humerus gets dislocated, then pass the cautery right through the skin thus drawn away." Since Hippocrates' description of capsule repair, a multitude of new techniques have been reported, all aimed at preventing recurrent dislocation or subluxation. These repairs can be divided into anatomic and nonanatomic. Anatomic repairs focus on repairing the structure that has been disrupted. With nonanatomic repairs (eg, Putti-Platt, Magnuson-Stack, and Bristow procedures), an attempt is made to shorten or tighten certain anterior structures regardless of the specific shoulder pathology. Early in the evolution of capsular repair, loss of motion was considered acceptable and even desired as a necessary part of stabilizing a shoulder. As new techniques followed, shoulder stability was achieved without significant loss of motion. Postoperative motion restriction is now considered a complication. In 1923, Bankart described the lesion of traumatic shoulder dislocation in the British Medical Journal, as follows: "The essential lesion is the detachment of the capsule from the fibro-cartilaginous glenoid ligament." He goes on to say, "... the only rational treatment is to reattach the fibrous capsule to the glenoid ligament whence it has been torn." In 1965, du Toit and Roux reported a similar procedure in which staples were used to attach the capsule to the anterior glenoid rim. This method had the potential to simplify the procedure, but it also added complications, such as glenoid damage from the staples and loosening. The Magnuson-Stack procedure was described next, in 1943. This procedure involves transferring the subscapularis from its attachment on the lesser tuberosity to a point lateral to the bicipital groove. The goal was to produce a sling effect on the humeral head. Like the Putti-Platt procedure that would follow, it decreased external rotation by design. In 1948, the Putti-Platt procedure was described. Here, the subscapularis tendon and capsule are divided longitudinally at the mid portion. The lateral free end is attached to the anterior rim of the glenoid, and the medial free end is attached over the lateral end. The Putti-Platt operation led to low dislocation recurrence rates, but it also led to decreased external rotation. In 1954, Latarjet proposed the Bristow procedure. This procedure was later popularized by Helfet, in 1958. This involved transferring the tip of the coracoid process with its muscular attachments. A vertical slit in the subscapularis allowed the osteotomized coracoid to be attached to the anterior glenoid with sutures. This procedure thus provided a bony block to anterior glenohumeral translation. ProblemThe term anterior glenohumeral instability describes the shoulder in which soft tissue or bony insult allows the humeral head to sublux or dislocate from the glenoid fossa. Function of these shoulders is compromised. Patients typically experience apprehension, recurrent subluxations, and frank dislocations. This pathology limits many activities, including overhead arm motions, external rotation, and thus, physical or athletic activities. FrequencyIn studies of anterior glenohumeral instability, a wide array of incidences have been proposed. Most report an average age of initial shoulder dislocation early in the third decade of life. The vast majority, 85-95%, of these are anterior dislocations. One fourth of all patients with dislocations present with a family history of the same problem. Rowe's 1956 analysis of 500 shoulder dislocations found only 8 occurred in children younger than 10 years; the largest cohort of dislocations occurred in the subsequent decade of life, in patients aged 10-20 years. The age at the time of dislocation is the biggest determinant of future recurrence. Recurrences result from anterior glenohumeral instability and occur most commonly in patients younger than 20 years. Reported recurrence rates in patients younger than 20 years vary from 70-100%. EtiologyThe cause of anterior glenohumeral instability can be traumatic or atraumatic. Either mechanism leads to the loss of balance in the surrounding muscular and capsular structures. Traumatic injury to any one component of the shoulder soft tissue leads to instability. This traumatic insult most commonly comes in the form of an anterior shoulder dislocation. Atraumatic causes leading to multidirectional instability are not the focus of this article. These causes include repetitive atraumatic injury, Ehlers-Danlos syndrome, Marfan syndrome, congenital absence of the glenoid, deformities of the proximal humerus, and emotional and psychiatric instability. PathophysiologyIn an unstable shoulder, many findings are possible. Each finding can occur alone or in combination with other lesions. These lesions include the Bankart lesion (in 85% of cases), Hill-Sachs lesion (in 77% of cases), anterior glenoid rim damage (in 73% of cases), capsular redundancy, subscapularis deficiency, and glenoid fossa deficiency. Absence of pathological findings is also possible. In 1923, Bankart described the "essential lesion" in posttraumatic anterior glenohumeral instability as the detachment of the capsule from the fibrocartilaginous glenoid ligament. In this lesion, the humeral head translates forward, shearing the inferior glenohumeral ligament (IGHL) with the anteroinferior labrum from the glenoid rim. Rowe's 1978 review of 28 patients in which he examined shoulder pathology after traumatic anterior dislocation disputed Bankart's claim to the essential lesion. Rowe's results showed "there was no evidence that there is a single essential lesion responsible for the recurrent dislocations of the shoulder." The Bankart lesions occurred in 27-100% of cases. Other lesions were just as variable. Subscapularis laxity ranged from being present in every case to not being present in any cases. Hill-Sachs lesions were present in 26-100% of cases. Anterior glenoid trauma of all variations occurred in 2-52% of cases. The next logical question is which of these lesions actually causes the recurrent instability observed after traumatic dislocations. This remains a debated topic. The most accurate conclusion is the one Rowe came to in 1978 when he declared that no single lesion is responsible for the recurrent dislocations of the traumatized shoulder. Several lesions have been suggested. In a 1990 report, Baker et al devised a system of classification for the Perthes-Bankart lesion, as follows:
Other lesions include attenuation of capsule and capsular ligaments, Hill-Sachs lesions, attenuation of the subscapularis, and humeral avulsion of the IGHL. ClinicalChildren presenting with a dislocated shoulder may relate a couple of possible mechanisms. These mechanisms occur in a number of ways and are similar to those in adults. Most commonly, the child falls on the outstretched hand, forcing the arm into abduction and external rotation, levering the humeral head out of the glenoid cavity. Activities promoting this injury include contact sports, falls from heights, fights, and motor vehicle accidents. Other mechanisms have been described, including elevation with external rotation and direct blows. A history of prior dislocations suggests a high likelihood of anterior glenohumeral instability. Studies have shown a 70-100% recurrence rate in various population groups of patients younger than 20 years. As with physical examinations of any joint, beginning by observing the shoulder is important. Note any atrophy of the biceps, supraspinatus, or infraspinatus. Gross deformities can also suggest the direction of a dislocation. Range of motion of the shoulder must be tested for restriction or hypermobility. Atraumatic instability generally manifests with hypermobility of the shoulder, whereas traumatic instability typically results in bilaterally symmetric motion. Generalized joint laxity is demonstrated by extending the elbow, wrist, metacarpal-phalangeal, and distal interphalangeal joints. External rotation can be increased as much as 28° or decreased as much as 14° after dislocation. Next, the examiner manually assesses translation of the humeral head in the glenoid fossa. The humeral head is grasped in one hand, and the clavicle and scapula are stabilized in the other as the examiner pushes anteriorly and posteriorly. This is known as a shoulder drawer sign. Compared with the unaffected shoulder, the affected shoulder often demonstrates increased laxity. Remember that as much as 50% of posterior translation may be normal. A sulcus sign is demonstrated by pulling inferiorly on the relaxed shoulder. A sulcus observed between the acromion and proximal humeral head is considered a positive finding. This finding indicates that the shoulder has multidirectional instability. The key finding in anterior glenohumeral instability is a positive apprehension test. The arm is placed in abduction, extension, and external rotation while stressing it in anterior translation. If the patient becomes apprehensive and reports pain, this is considered a positive finding. The relocation test involves placing the shoulder in the position of apprehension and applying a posteriorly directed force on the humeral head. The result is considered positive if this relieves the patient's apprehension. Impingement signs must also be evaluated because as many as 10% of patients experience impingement after dislocation. Evaluate for the Hawkins sign and perform the Neer impingement test. INDICATIONSThe indications for open surgical repair depend on the individual surgeon. Shoulders in which conservative therapy has failed or any shoulder rendered unstable may undergo open repair. Frequently, classifying patients into one of two categories helps to determine treatment. Young patients with heavy physical demands may forego conservative therapy and proceed to immediate surgical repair. This recommendation is based on the high recurrence rate and the patient's desire to return to activity. In contrast, older patients who are less physically demanding may try conservative therapy prior to assuming the risks of surgical repair. These patients have a lower likelihood of recurrence and may only require conservative therapy. Surgery is also indicated if the patient is symptomatic with activities of daily living or if overhead stability is specifically needed. The patient must understand that overhead stability cannot be guaranteed. RELEVANT ANATOMYThe shoulder joint is a simple structure that provides complex function. It is the most mobile joint of the body, and it is also the joint that is most frequently dislocated. The gross anatomy consists of 3 main components: musculature, capsule/ligaments, and bone. Capsuloligamentous structures provide the primary stabilization for the joint. The capsule of the shoulder joint extends from the periphery of the glenoid around the articular surface of the proximal humerus. Within this capsule are 3 distinct thickenings that constitute the superior glenohumeral ligament (SGHL), middle glenohumeral ligament (MGHL), and IGHL. The SGHL and MGHL attach proximally at the anterosuperior portion of the glenoid labrum. The proximal attachment of the SGHL has 2 origins, including the one at the apex of the labrum that is joined with the long head of the biceps brachii and a second origin at the base of the coracoid process. Distally, the SGHL attaches just superior to the lesser tuberosity at the edge of the articular surface. The MGHL inserts just medial to the lesser tuberosity. The IGHL is the key stabilizer of the shoulder, preventing anterior glenohumeral instability. The IGHL attaches proximally to the anterior, inferior, and posterior margins of the glenoid labrum. Distally, it attaches to the inferior margin of the anatomic neck of the humerus. Together, the glenohumeral ligaments function to limit lateral rotation of the shoulder. Each of the 3 ligaments is relied upon for stability, depending on the position of the arm. In 1910, Delorme found that the MGHL tightens as the arm is externally rotated or dorsally flexed. If the arm is then abducted, the IGHL becomes the primary stabilizer, with the upper fibers tight at slight abduction and the whole ligament tightening at about 45° of abduction. The secondary stabilizers of the shoulder joint are the surrounding musculature. This consists of the rotator cuff muscles. The supraspinatus, infraspinatus, teres minor, and subscapularis are intimately associated with the capsule. These muscles provide dynamic secondary stabilization. Conservative therapy focuses on strengthening the rotator cuff muscles to prevent recurrent dislocation. The subscapularis is the most important contributor of the rotator cuff muscles to anterior shoulder stability. With the arm adducted, it tightens with external rotation. Cutting it results in 15-20° of increased external rotation. At 45° of abduction, the subscapularis becomes taught over the anterior joint surface and ascends so its inferior margin lies at the inferior margin of the glenoid. External rotation raises it even further and makes it more taught. Finally, at 90° of abduction, the inferior portion of the subscapularis no longer covers the inferior humeral head. It continues to provide anterior stabilization by remaining taught. The glenoid fossa provides a shallow socket in which the humeral head articulates. It is composed of the bony glenoid and the glenoid labrum. The labrum is compared to the menisci of the knee. It is a fibrocartilaginous structure surrounding the periphery of the glenoid. Like the menisci of the knee, it is flexible but constant; when torn, it generally does not heal. The stability of the glenohumeral joint is greatly increased by the labrum, which provides a 50% increase in the depth of the concavity. The bony concavity measures approximately 2.5 mm and has been measured at 5.0 mm with an intact labrum. In 1923, Bankart claimed that anterior inferior detachment of the labrum from the glenoid was the essential lesion in anterior glenohumeral instability. It has since been proven that this is true in most cases of instability but is not required for instability. The labrum is closely related to the joint capsule and the glenohumeral ligaments. It is anchored to the bony rim of the glenoid and can be attached to the capsular structures as well. Finally, understand the supporting musculature of the scapula that allows such a wide range of motion at the shoulder. A total of 16 muscles move and stabilize the scapula. CONTRAINDICATIONSSurgical repair is relatively contraindicated in older patients with low physical demand, who have little chance of recurrence. Conservative therapy, including physical therapy to strengthen the rotator cuff, is indicated rather than exposing these patients to the risks of operation. Patients who have been asymptomatic in their activities of daily living also need not be exposed to the risks of surgery. These patients are best monitored for any recurrent dislocations. A certain contraindication exists in the case of multidirectional instability of the shoulder. In these atraumatic dislocations, patients are able to voluntarily dislocate and relocate their shoulder. Predisposing factors include psychiatric dislocations, laxity due to repetitive injury as occurs in competitive swimmers, and congenital collagen abnormalities such as Ehlers-Danlos syndrome and Marfan disease. The history and physical examination must be used to identify these patients. If these patients are treated as patients with unidirectional dislocations, operative therapy will fail. The amount of inferior capsular redundancy in multidirectional instability requires an operative procedure addressing the possibility of future inferior instability. WORKUPImaging Studies
TREATMENTMedical therapyNonoperative management of pediatric anterior glenohumeral instability must be considered. This treatment consists of a period of shoulder immobilization. Subsequent physical therapy reestablishes range of motion and strengthens the rotator cuff. The first consideration in attempting nonoperative therapy is the age of the patient. Rowe found significantly higher recurrence rates in young patients. Those younger than 10 years had a 100% recurrence rate, which decreased to 94% in those aged 10-20 years, to 79% in those aged 20-30 years, and to 50% in those aged 30-40 years. In a 1992 report, Marans showed a 100% redislocation rate in 21 patients with an average age of 13 years with open physes. In 1984, Simonet and Cofield found an 87% recurrence rate in athletes versus a 30% recurrence rate in nonathletes. In a 2002 report, Mehlman et al suggested that the rate of recurrence is not as high as previously reported. They found a redislocation rate of 76% in a group of 33 patients aged 2-18 years. Because the recurrence rate is 76-100% in juvenile patients, more aggressive initial therapy is certainly justified. In older more sedentary patients, immobilization in adduction and internal rotation is a valid option. The period of immobilization is debatable. In 1983, Hovelius compared early motion to 3-4 weeks of immobilization and found no difference in redislocation rates. Nonoperative therapy has also been compared to arthroscopic repair. Wheeler and Arciero's 1989 study resulted in 80% redislocation for nonoperative treatment, using 1 month of immobilization. This is compared to an 86% success rate in those treated by arthroscopic repair. More important, it seems, is the physical therapy program. This should focus on isotonic strengthening before isokinetic strengthening. The first musculature to rehabilitate is that of the scapula, serratus anterior, and then rhomboids. The deltoids follow, and finally, strengthening should focus on the rotator cuff. No substantial evidence supports physical therapy as a treatment for high-risk patients. Thus, conservative management is reserved for persons with first-time dislocations who are older than 20-25 years and are sedentary. Surgical therapyIndications for repairing an anteriorly unstable shoulder are not obvious. The patient and surgeon must consider the possible outcomes based on the patient's activity level and the most probable natural history of the individual's instability. At times, foregoing conservative therapy and proceeding directly to surgical repair may be appropriate. In the case of a patient who has experienced dislocation fewer than 3 times, attempting an arthroscopic repair is reasonable. Arthroscopic repair is associated with a lower incidence of shoulder stiffness but has been shown to have a higher risk of recurrence. Persons with truly recurrent dislocations have dislocated their shoulder more than 3 times. In these cases, patients may want to risk the possibility of stiffness in return for the stability created by an open Bankart repair. Many options exist for the surgical repair of anterior glenohumeral instability. Arthroscopy provides the least invasive repair. Open shoulder repairs include Putti-Platt, Bristow, Magnuson-Stack, inferior capsular shift, Eden-Hybbinette, and the Bankart procedures. Arthroscopic repair has potential advantages including improved cosmesis, less postoperative pain, shorter operative time, decreased blood loss, better preservation of external rotation, and avoidance of subscapularis related complications. Intraopertively, arthroscopy provides better visualization of the joint. Although recurrence rates in persons with first-time dislocations has been reported as low as 5%. More recent literature suggests recurrence rates rivaling those of open bankart repairs. In addition, the operative procedure does require significant training. Proper patient selection has led to good outcomes in arthroscopically repaired shoulders. Good candidates for arthroscopy are those who have a discrete Bankart lesion, a well-developed IGHL, no significant capsular laxity, no intraligamentous injury, no concomitant intra-articular pathology, and unidirectional instability. Patients who require open repairs are those with capsular injury, capsular laxity, bony Bankart lesion, glenohumeral arthritis, rotator cuff tear, or poor tissue quality. Preoperative detailsSeveral issues are important preoperatively. Most significantly, anterior shoulder instability must be confirmed. The shoulder should be examined again after anesthesia is induced. If the shoulder is found to have multidirectional instability, the operative procedure should be canceled and revised. Arthroscopic repair may be intra- or extra-articular. Extra-articular repair is primarily indicated for labral tears. Damage that is more extensive requires an intra-articular repair. The arthroscopic repair can be performed in either the lateral recumbent or beach chair position. Remember that the lateral position has been associated with traction neuropraxia and allows less joint motion. The beach chair position is convenient if a conversion to an open repair is anticipated. There are several keys to a sucessful arthroscopic bankart repair. They include patient selection, proper mobilization of capsulolabral tissues, repair of the tissue to the edge of the articular surface (not the glenoid neck), and identification and treatment of capsulolabral injury. Preoperative radiography helps determine the presence of a bony Bankart lesion. Intraoperative detailsAlthough the procedure has evolved through the years, the open Bankart repair has remained essentially unchanged from the original description by Rowe in 1978. First, the patient's shoulder is examined under anesthesia to ensure that the patient truly has purely anterior instability and thus can benefit from a Bankart repair. An incision is made from the coracoid process inferiorly to the axilla. The deltopectoral groove is dissected, exposing the cephalic vein and retracting it. The coracoid process is now osteotomized, allowing the coracobrachialis and short head of the biceps to retract inferiorly. External rotation of the arm exposes the subscapularis. The circumflex vessels at the inferior border of the muscle can be ligated. The subscapularis is then separated from the capsule. With the arm fully externally rotated, a vertical incision is made in the subscapularis just lateral to the glenoid rim. This provides a large flap for repair of the capsule with adequate external rotation postoperatively. With the humeral head retracted posterolaterally, the rim of the glenoid and the anterior neck of the scapula are freshened using a small osteotome. Three holes are made in the anterior glenoid rim. They are located at 1, 3, and 5 o'clock on the right glenoid and 11, 9, and 7 o'clock on the left glenoid. A double No 0 suture is passed through each hole and then through the edge of the lateral capsular flap. This is tied while the capsular flap is held to the freshened anterior glenoid rim. Using the same suture ends, the medial capsular flap is then tied down on top of the lateral one. This reinforces the capsule at the rim of the glenoid. External rotation must now be checked and should extend easily to 25-30° beyond neutral. Closure is achieved by returning the tissues to their anatomic positions. The subscapularis is sutured to the lesser tuberosity and secured. Thus, the muscle is not shortened, overlapped, or transplanted as in other techniques. The coracoid is anchored in place using No 0 suture at its base. No separation of the coracoid has been described using suture to anchor it. The arthroscopic procedure for a soft Bankart lesion also starts with examination under anesthesia. The patient may be in the lateral recumbent or beach chair position. Access to the joint starts with a posterolateral glenohumeral portal for viewing the joint. A thorough examination is performed prior to making an anterior working portal lateral to the coracoid. The edge of the gloenoid articular cartilage is abraded. The capsulolabral complex is dissected and then grasped and advanced over the abraded bone. Anterior reconstruction is then performed using suture anchors and plicating the loose anterior capsule into the labral repair. The most inferior suture is placed first, allowing superior sutures to further tighten the capsuloligamentous complex. The sutures are tightened with the shoulder in internal rotation. Range of motion can be examined intra-articularly, and the incisions are closed. Postoperative detailsPostoperatively, the shoulder is kept in an arm sling for 3-4 weeks. The shoulder may be internally rotated and flexed for hygiene maintenance, but external rotation is prohibited. After 4 weeks, full active flexion is encouraged and assisted with physical therapy. At 6 weeks, internal and external rotation of the shoulder is begun using 5- and 10-pound weights. At 3 months, full and unrestricted weightlifting is allowed. Competitive throwers should be restricted from unrestricted athletics for 6 months. At 3 months, the patient should have regained 70% of external rotation and elevation of the shoulder. At 6 months, 75-100% of normal motion and strength may be observed. Follow-upFollow-up care can be scheduled on an annual basis after patients have returned to full activity and strength. At these visits, any symptoms of subluxation or dislocation should be explored. The shoulder range of motion, strength, and stability are examined, and a radiographic examination is also performed. COMPLICATIONSSuccessful repair of anterior glenohumeral instability is extremely rewarding and can render a patient fully functional within months. However, as in any surgical procedure, complications are possible. Unsuccessful surgery in this case can be one of the most difficult to salvage. The most commonly reported complication of open Bankart repair is persistent instability. Reported rates of recurrent instability range from 3-50%. The cause of failure should be determined. The most common adverse effect of anterior instability is loss of motion. Frequently, decreased external rotation of the humerus is desired to prevent recurrent dislocation; thus, the loss of motion is not reported as a complication. Note that complications of decreasing the normal shoulder range of motion can be serious. In athletes, the late cocking position is disabled, thus decreasing the velocity of their throw. More extensive reductions in external rotation can cause posterior translation of the humeral head. A 1990 study by Hawkins and Angelo found that Putti-Platt repairs in 7 patients resulted in tight anterior structures, which led to glenohumeral arthritis. The Putti-Platt procedure is not the only repair technique that may result in tight anterior structures. The classic Bankart repair has also been shown to cause limitation of motion and, thus, arthritic changes, both clinically and radiographically. How much limitation in motion is required to cause late degenerative arthrosis is yet to be determined. Based on studies to date, small limitations in motion are presumed not to cause significant degenerative changes. Excessively tight anterior capsules need to be addressed to prevent premature arthritic changes. The subscapularis can be released and sutured back into place with the arm eternally rotated to the desired position. For greater restrictions, requiring over 20° of correction, the subscapularis is dissected in the coronal plane, creating a superficial and deep layer. The medial edge of the deep layer of the subscapularis can be sutured to the lateral edge of the superficial layer. An incorrect diagnosis prior to surgery undoubtedly leads to failure. This can occur when atraumatic multidirectional shoulder instability is confused with traumatic unidirectional anterior instability. In the case of the former, an inferior capsular shift is in order, as opposed to the latter when an open or arthroscopic Bankart repair is indicated. Voluntary instability is a contraindication to any surgical repair mentioned above. These patients can dislocate their shoulders using muscular contractions or arm positioning. A study by Rowe found that most people who dislocate their shoulders voluntarily have "significant psychiatric histories." Nonoperative treatment is necessary in these patients. Nonanatomic repairs have been shown to result in higher postoperative instability rates. Using the original Bankart repair, the anterior glenoid is essentially reconstructed to its original anatomic shape. Procedures that fail to reconstruct the anterior glenoid have been shown to fail more frequently. Bony Bankart lesions, if large enough, leave a glenoid fossa that lacks concavity. Defects involving greater than 20% of the articular surface must be addressed. Bony lesions involving less than 20% of the glenoid can be resected with the capsulolabral mechanism reattached to the remaining anterior glenoid. Osteochondral defects of the humeral head may predispose a shoulder to continued instability. A Hill-Sachs lesion alone infrequently causes instability but coupled with a Bankart lesion creates an easily subluxed or dislocated shoulder. Preoperative CT scanning of the Hill-Sachs lesion helps determine the need for repair. The humeral lesion can be prevented from perching on the anterior glenoid by imbricating the anterior capsule and thus decreasing external rotation. Other methods of filling in a Hill-Sachs defect have been described, including transfer of the infraspinatus with a portion of greater tuberosity (Connolly, 1972), humeral osteotomy (Weber, 1984), and humeral hemiarthroplasty or osteochondral allograft for defects involving more than 40% of the head's articular surface. Another cause of surgical failure is rupture of the subscapularis. Patients may present after a traumatic event or with persistent postoperative pain, weakness, or continued instability. Physical examination reveals increased external rotation and positive lift-off test results. MRI may be helpful in confirming this complication. Operative repair includes mobilization of the tendon, which frequently retracts underneath the conjoined, and reattachment to its insertion. Hardware placed in or around the glenohumeral joint can always cause complications. Loosening and failure has been shown to occur at any time point after surgery. In a 1984 report, Zuckerman found that the most common culprits were screws or staples that were placed for a coracoid transfer or anterior capsular plication. Most of these failures require reoperation. Chondral damage was found in 41% in Zuckerman's report. OUTCOME AND PROGNOSISOutcomes of anterior glenohumeral repair rely on identification of all of the patient's pathology and choosing the correct repair. With these key factors addressed, patients can expect a low incidence of complications, good range of motion, and stable repairs with a low incidence of recurrence. FUTURE AND CONTROVERSIESThe future of anterior glenohumeral instability brings significant advancements. Great room for improvement exists, especially with arthroscopic treatment. Currently, the key to success in arthroscopic repairs is good patient selection. Studies will continue to delineate which patients can best be treated with arthroscopic repair. Advancements in techniques and equipment will allow for arthroscopic repairs in patients that would currently be treated with an open repair. The rate of recurrence in arthroscopically treated patients will continue to approach that of open repairs. In the future, significant plastic deformity, rotator cuff interval lesions, and other unrecognized intra-articular lesions will be addressed arthroscopically. These new indications could be treated with thermal capsulorraphy and other new instrumentation. Open repairs will continue to provide good functional results. Postoperative range of motion of the shoulder in patients who undergo open repair will continue to approach that of arthroscopically treated patients. REFERENCES
Anterior Glenohumeral Instability excerpt Article Last Updated: Jul 7, 2004 |