Arthroscopic treatment of multidirectional instability—surgical technique

CHAPTER 32 Arthroscopic treatment of multidirectional instability—surgical technique



Felix H. Savoie, MD, Michael J. O’Brien, MD



Key points



image The diagnosis of multidirectional instability (MDI) is made by physical examination showing symptomatic subluxation in an anterior-posterior direction, with associated inferior laxity demonstrated by a positive sulcus sign in adduction, abduction, and external rotation.

image MDI should be managed by nonoperative treatment including scapular bracing, taping and rehabilitation, control of inflammation, biofeedback therapy, and integrated rehabilitation for at least 3 months before any consideration of surgical intervention.

image If surgery is being considered, arthroscopy provides the best surgical option in most cases of MDI.

image Surgical techniques should center on restoration of the humeral head into the center of the glenoid by capsular plication and/or repair to anchors, restoring the entire inferior glenohumeral ligament and reformation of the superior and middle glenohumeral ligaments.

image The pathologically widened rotator interval should be closed with multiple sutures in order to restore the normal resting tension of the coracohumeral ligament and provide support for the shoulder in adduction.


Introduction


Multidirectional instability (MDI) of the shoulder is a condition in which the shoulder demonstrates symptomatic laxity in an inferior direction and in the anterior and/or posterior direction. MDI was first described in 1980 by Neer and Foster.1 They reported on a group of patients who had pain and laxity in the anterior, posterior, and inferior directions. They successfully eliminated the symptoms in most patients using a humeral-based open inferior capsular shift procedure. Savoie described the first arthroscopic treatment of MDI in a pilot study using a modification of the Caspari transglenoid capsular shift technique2,3 and many surgeons have expanded and improved on this original idea of the use of arthroscopy for MDI.


Several reports have been published showing excellent results with arthroscopic treatment of the patient with multidirectional instability. Duncan and Savoie3 presented a 1- to 3-year postoperative follow-up study revealing improvement in all patients treated by an arthroscopic version of the Neer capsular shift. The average postoperative Bankart score was 90, and all had a “satisfactory” score according to the Neer system.


Wichman and Snyder4 reported results of arthroscopic capsular shift for MDI in 24 patients with an average age of 26 and a minimum follow-up of 2 years. Five patients (21%) had an “unsatisfactory” rating according to the Neer system.


Treacy and Savoie5 reported on 25 patients with multidirectional instability of the shoulder who underwent an arthroscopic capsular shift. At an average 5-year follow-up, 3 patients had episodes of subluxation but none had recurrent dislocation. According to the Neer system, 88% of the patients had “satisfactory” results.


Gartsman6 reported on 47 patients who underwent arthroscopic capsular plication for MDI. Ninety-four percent had “good” to “excellent” results at an average follow-up of 35 months. Eighty-five percent of athletes returned to their desired level of participation.


Neer felt that correction of the pathologic laxity of the rotator interval was a necessary part of MDI surgery. Lyons7 showed favorable results with an arthroscopic laser-assisted technique in which the rotator interval was plicated with multiple sutures to improve stability. Twenty-six of 27 shoulders remained stable at a 2-year follow-up. Eighty-six percent of athletes returned to their sport at the same level. Field et al reported on 15 cases of open interval plication for “mild” MDI with satisfactory results.8 Recently, excellent laboratory work by Provencher et al called into question the value of the standard arthroscopic rotator interval closure, suggesting other methods that more accurately mimic the open technique may be necessary to achieve satisfactory correction of the inferior instability.9–12


McIntyre13 reported results of arthroscopic capsular shift in MDI patients using a multiple suture technique in both the anterior and posterior capsule with a 32-month follow-up. Recurrent instability occurred in 1 patient (5%), who was treated successfully with a repeat arthroscopic stabilization. Thirteen athletes (93%) returned to their previous level of performance.


Hewitt14 demonstrated favorable techniques and results in a review article of multidirectional instability of the shoulder using a pancapsular plication suture technique.


Tauro and Carter15 reported preliminary results of a modified arthroscopic capsular shift for anterior and anterior-inferior instability in 4 patients with a minimum follow-up of 6 months. No patients developed recurrent instability in this short-term follow-up period.


The main areas of controversy in the management of MDI include proper diagnosis, proper length of the period of preoperative rehabilitation, and choice of surgical technique (open shift versus arthroscopic shift, how to and the necessity for, rotator interval closure).



Indications


The main indication for surgery is pain and functional impairment that have not responded to extensive nonoperative treatment, including scapular bracing and taping. The symptomatic pattern of the instability should be ascertained before surgical treatment. The shoulder may demonstrate laxity in many directions and have symptomatic instability in only one direction. Asymptomatic, normal laxity does not usually need to be surgically addressed.




Indications Pitfalls


The primary cause of concern is the decision for surgery: the proper diagnosis is essential and each patient should have had extensive, proper therapy before any indication for surgery. This must include postural correction and integrated rehabilitation. In Neer’s original work, he recommended a full year of therapy before any indication for surgery in the patient with true MDI.1



Contraindications


There are several contraindications to surgical intervention in the MDI patient. The first is a failure to have attempted an adequate rehabilitation program. Another is the psychiatrically impaired voluntary dislocator. These patients often have secondary gain issues associated with this type of dislocation and will often try to redislocate the shoulder after the surgical shift of the tissues, making any surgery usually fruitless.


Patients with known connective tissue disorders also are poor surgical candidates for a standard capsular shift procedure. Ehlers-Danlos syndrome is one such condition. It is characterized by skin hyperextensibility, joint hypermobility and dislocation, bone/skin fragility, and soft-tissue calcifications. There are multiple subtypes of Ehlers-Danlos syndrome, but they all interfere in some way with the formation of type I and type III procollagens. With abnormal type I and type III collagen, healing occurs normally, but the scar tissue is replaced by the patient’s own normal, poor quality ligaments. Surgically shifting this abnormal tissue gives a variable success rate. Laxity and capsular redundancy can redevelop very quickly after surgical shift of the tissue. If surgery is an absolute necessity in these patients, we recommend the use of allograft tissue to supplement the repair.16




Pearl


As can be seen, there are no absolute indications or contraindications for surgical intervention. The surgeon uses his or her best judgment to provide a solution for the patient. However, if there is any doubt, the prudent choice is to continue nonoperative management rather than opt for early surgery in patients with this disorder.



Preoperative history, examination, and radiographic findings


A detailed history is extremely important in evaluating all shoulder patients, but this is especially true for the patient with MDI. The initial episodes of both laxity and instability should be noted. Many MDI patients will have noted multiple asymptomatic episodes of “shifting” throughout their life until a specific activity or injury initiated a pain cycle. The usual patient will be in their teens or twenties. The most common complaint is pain, exacerbated by activities of daily living. This often becomes worse at night and following increased activity, resulting in a cycle of pain, protection, and attempts at activity, with worsening of the pain. Athletes may present with pain during the sporting event, with worsening after the activity. The level of pain, timing of pain, and chronicity of pain must be recorded. The activity level of the patient and the specific sport (if any) should be recorded as well. Questions should be directed to the patient to determine if popping, clicking, subluxation, or dislocation are associated with the pain. The number of such episodes needs to be determined, as well as the amount of trauma it took to produce the episode. Some patients also will give a history of transient neurologic deficits associated with subluxation.



Examination findings


The physical exam starts with visual inspection of the patient. Unclothe the shoulder to be able to see the entire arm, upper chest, scapula, and trapezius. Note the position of the scapula at rest. Symptomatic MDI patients present with a protracted shoulder, held in for “support,” and are hesitant to move it at all because of coexisting inflammation of the rotator cuff. The first task is to determine the tracking patterns of the entire shoulder girdle. Ask the patient to actively abduct and flex the arm in the pain-free range and observe the scapula tracking patterns. General muscle tone also should be evaluated during these active motions. Note any atrophy and the area where found. The shoulder may have a squared-off appearance because of the prominence of the acromion secondary to inferior subluxation of the humeral head.


Palpate the shoulder for widening of the rotator interval and for swelling of the rotator cuff tendons. Feel for areas of tenderness and inflammation. One area of interest is the pectoralis minor tendon insertion on the coracoid, often an area of pain and contracture in MDI patients with long-standing uncorrected protraction of the scapula.


Evaluate the degree and direction of both laxity and instability. The initial exam is performed with the patient sitting up. Place one hand on the proximal humerus and the other hand on the elbow. Apply a load in the anterior, posterior, and inferior directions. A circumduction maneuver can demonstrate subtle instability and is a good way to start the exam. Note the degree of humeral head movement on the glenoid in each direction. Check for a sulcus sign in neutral rotation and repeat with the arm in external rotation and abduction. Repeat the exam with the patient supine and also perform a load-and-shift test in the anterior and posterior directions in varying degrees of shoulder abduction: in a patient with a normal inferior glenohumeral ligament (IGHL) the degree of shifting should decrease with increasing abduction as the anterior and posterior bands of the IGHL tighten. This also can be performed with the patient on his or her side if the scapula is stabilized. Always compare the degree of shifting to the symptomatic opposite shoulder.


Evaluate the strength of the rotator cuff and any pain associated with manual muscle testing. MDI patients will often develop a rotator cuff tendonitis and exhibit significant pain with manual muscle testing. Preferred tests of the rotator cuff include the Whipple test, supraspinatus stress test, supraspinatus isolation test, external rotation test and belly-press test. The Whipple test is performed in 90 degrees of forward flexion with the arm adducted until the hand can be placed palm down in a line in front of the opposite shoulder. Have the patient resist a downward pressure. A positive test is recorded when the humeral head shifts and the arm buckles downward with the pressure. The supraspinatus stress and isolation tests are performed in the scapular plane in 90 degrees of abduction. Have the patient resist a downward pressure with the thumb turned down (SS stress test) and with the thumb turned up (SS isolation test). The supraspinatus stress test will be more painful in patients with posterior superior rotator cuff pathology. The supraspinatus isolation test will be more painful with anterior superior rotator cuff pathology. If the rotator cuff is weak, check for scapular protraction. If there is scapular protraction present and the rotator is weak and painful, check for normalization of shoulder strength with manual scapular stabilization. Next, perform the external rotation test with the arm in slight abduction and 45 degrees of external rotation. Have the patient resist an inward pressure on the hand. The belly-press test is performed by placing the hand on the abdomen and maintaining the elbow in front of the body. Have the patient resist an attempt to pull the hand off of the abdomen. Rate the strength according to the standard manual muscle testing system and determine the level of pain associated with the tests. Compare with the contralateral side.


Evaluate the cervical spine for motion. Determine if there are any nerve root compression symptoms.


The vascular status of the arm should be evaluated by performing the Adson test, checking the pulse with the arm abducted to 90 degrees and externally rotated to 90 degrees. In many MDI patients, this will produce transient vascular compromise and a diminished pulse. Manual scapular retraction will relieve pressure and restore a normal pulse. This variation of the Adson or Leffert test demonstrates to the patient the etiology of the numbness, tingling, and vascular changes that may occur in this condition because of poor scapular control.


Evaluate the range of motion of the other extremities and check for hyperelasticity of the knees, elbows, and metacarpophalangeal joints. Note any and all joints that exhibit hyperextension and/or hypermobility.




Pearl


Key points in the physical exam are the position of the scapula, the direction and degree of laxity, and the comparative size of the sulcus in adduction, external rotation, and abduction.



Radiographic findings


The most commonly used imaging modalities are plain radiographs and magnetic resonance imaging (MRI). Plain radiographs are often normal but should be evaluated for any bony deficiency of the glenoid or humeral head. MRI scans are often employed in the evaluation of the patient with MDI. An MRI with intra-articular contrast (MRA) is most helpful. A typical MRA finding is a large capsular volume. There will be a large axillary recess in many cases. The appearance is that of an upside-down bubble extending inferiorly below the glenoid in the coronal sections. One pathognomonic hallmark of MDI, as described by Neer in some of his original thoughts on MDI, is bulging of the rotator interval on arthrogram.17 If there is significant rotator interval laxity, you may be able to see the entire intra-articular portion of the biceps tendon silhouette. The underside of the rotator cuff and rotator interval may have space between them and the biceps tendon in the coronal sections. The axial sections will show capsular laxity in the anterior and posterior sides of the joint usually in the lower sections of the glenoid. Evaluate the scan for any signs of labral degeneration, tears, or malformation. Always try to determine the integrity of the rotator cuff. Evaluate for any cysts within the spinoglenoid notch. Although usually normal, check the quality and integrity of the rotator cuff and appearance of the supporting muscles.

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Jan 21, 2017 | Posted by in ORTHOPEDIC | Comments Off on Arthroscopic treatment of multidirectional instability—surgical technique

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