Level V Evidence. Minor Shoulder Instability. Alessandro Castagna, M.D., Ulf Nordenson, M.D., Raffaele Garofalo, M.D., and Jon Karlsson, M.D., Ph.D.

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1 Level V Evidence Minor Shoulder Instability Alessandro Castagna, M.D., Ulf Nordenson, M.D., Raffaele Garofalo, M.D., and Jon Karlsson, M.D., Ph.D. Abstract: The wide spectrum of shoulder instability is difficult to include in 1 classification. The distinction between traumatic, unidirectional, and atraumatic multidirectional instability is still widely used, even though this classification is not sufficiently precise to include all the different pathological findings of shoulder instability. We present minor instability, which is a pathological condition causing a dysfunction of the glenohumeral articulation, especially in combination with microtrauma, repetitive or not, or after a period of immobilization or inactivity. When minor shoulder instability is suspected, the patient s history and detailed clinical examination represent the most important factors when establishing the diagnosis. In particular, the apprehension test stressing the middle glenohumeral ligament (MGHL)/labral complex in the position of midabduction and external rotation may be painful and may even reveal anterior instability or subluxation. Conventional radiographs are negative in most cases, as is magnetic resonance imaging arthrography. It is only after an accurate arthroscopic assessment that the pathological lesion can be found. The major pathological process can be identified at the level of the anterior superior labrum, in particular the MGHL complex, and appears as hyperemia, fraying, stretching, loosening, thinning, hypoplasia, or even absence. It may, however, be difficult to distinguish between a normal variant and a pathological lesion. Clinical symptoms and examination should always be correlated with arthroscopic findings. Recommended treatment is to restore shoulder stability and thereby prevent shoulder pain secondary to the increase in laxity. A reduction in range of motion should be expected during the postoperative phase, at least up to six to nine months. External rotation is usually permanently reduced by a few degrees. Key Words: Shoulder Instability Labrum Subluxation Middle glenohumeral ligament. Recent advances in arthroscopic shoulder surgery have added enormously to the information relating to the pathological anatomy of shoulder instability. Traditionally, glenohumeral joint instability has been regarded as either TUBS (traumatic From Unità di Chirurgia della Spalla IRCCS Instituto Clinico Humanitas (A.C., R.G.), Milan, Italy; and Department of Orthopaedics, Sahlgrenska University Hospital (U.N., J.K.), Göteborg, Sweden. The authors report no conflict of interest. Address correspondence and reprint requests to Ulf Nordenson, M.D., Department of Orthopaedics, Sahlgrenska University Hospital, SE Mölndal, Sweden. ulf.nordenson@ vgregion.se 2007 by the Arthroscopy Association of North America /07/ $32.00/0 doi: /j.arthro unidirectional Bankart lesion, responds to surgery) 1 or AMBRII (atraumatic, multidirectional, bilateral, responds to rehabilitation, inferior capsular shift, and interval closure). 1,2 This classification is still meaningful, but it is not comprehensive enough to include all the different kinds of shoulder instability. It has become evident that there is a large spectrum of instability patterns between these 2 conditions, which cannot be classified strictly as either TUBS or AMBRII. In particular, there is a group of subtle conditions, which may be identified as minor shoulder instability, that are responsible for pain and dysfunction in the shoulder. 3 Minor shoulder instability is defined as shoulder pain secondary to shoulder laxity, which cannot be defined as TUBS or AMBRII. Minor shoulder in- Arthroscopy: The Journal of Arthroscopic and Related Surgery, Vol 23, No 2 (February), 2007: pp

2 212 A. CASTAGNA ET AL. cludes an acquired instability in overstressed shoulder (AIOS) 4-7 and an atraumatic minor shoulder instability (AMSI). 7 AIOS may represent shoulder subluxation, anteroinferior subluxation, dead arm syndrome (in throwing athletes), or chronic microtrauma associated with capsular laxity, In patients with TUBS, the common finding is the typical Bankart lesion, as well as the Hill-Sachs lesion, whereas in AMBRI no obvious structural lesions are found in a joint with thin, weak structures and large capsular volume. AIOS describes a pathological process, related to overstress (chronic microtrauma), involving the superior half of the capsular-ligamentous complex. In AMSI, anatomic variants of the middle glenohumeral ligament (MGHL) are expected. AIOS occurs most frequently in overhead athletes (ie, pitchers, volleyball players, and tennis players) or in heavy overhead young workers, such as builders, painters, and forklift drivers. Both static and dynamic shoulder stabilizers are of major importance because dysfunction in either of these will lead to the overload and failure of its counterpart, with subsequent minor glenohumeral instability. Different theories exist in the literature as to why these overhead activities can lead to AIOS. Townley 8 noted that the instability was related to the dysfunction of the MGHL. Andrews et al. 9 showed that overhead athletes who have excessive external rotation plus tightness in internal rotation develop injuries to the superior labrum and anteriorsuperior glenoid rim in the absence of a complete anterior capsular-labral detachment. Harryman et al. 10 noted that a posterior capsular retraction results in superior translation of the humeral head. Jobe 11 and Walch et al. 12 believe that a recurrent abduction/external rotation movement leads to the progressive weakening of the anterior-inferior translation of the humeral head. Savoie et al. 13 have shown that microtrauma in midabduction/external rotation can lead to the detachment of the MGHL. Burkhart and Morgan 14 proposed that abduction/external rotation might stress the bicipital anchor to the posterior glenoid labrum (peel-back mechanism). The SLAP lesion is thus responsible for subtle posterior-superior instability, which can mimic anterior-inferior pseudolaxity. Moreover, the presence of contracted posterior inferior capsule results in inappropriate translation of the humeral head and injury to the biceps anchor. We believe that traction applied to the insertion slowly enlarges the sublabral foramen and changes the tension of the MGHL, which will contribute to the development of minor instability. In the presence of a sublabral foramen and if fraying and/or the detachment of the anterior biceps anchor is noted, the traction of the cordlike MGHL will stretch the attachment and damage the anchor. This lesion may in fact evolve to become a SLAP lesion in overhead athletes. In addition, given enough time, repetitive overhead microtrauma may stretch the MGHL causing subtle anterior instability and posterior-superior impingement. The MGHL is the primary anterior stabiliser at 45 of abduction and limits external rotation. In subjects who perform overhead activities, this ligament can fail, leading to abnormal anterior translation and AIOS. AMSI is a rare condition and very seldom discussed in the literature. Patients complain about shoulder pain after a period of inactivity such as pregnancy or immobilization. This group of patients does not generally display generalized joint laxity. These patients may have static anatomic variants of MGHL (absence, hypoplasia, or a large sublabral hole or Buford complex) Equilibrium is disturbed, congenital insufficient static stabilizers are overloaded, and symptoms develop. Clinical Findings Patients with minor shoulder instability complain of pain in the posterior-superior aspect of the affected, generally dominant, shoulder. Sometimes, the pain radiates toward the arm. The pain is often diffuse and difficult to pinpoint. Patients describe snapping and popping, dead arm, painful subluxation, or transient locking. On examination, range of motion testing in patients with AIOS reveals increased external rotation in abduction combined with reduced internal rotation. Stressing the MGHL-labral complex in midabduction (between 45 and 80 ) and external rotation causes pain or apprehension. The load and shift or fulcrum test can reveal increased translation and crepitus. Strength testing typically reveals no deficits. However, the Jobe test, 19 Whipple test, 20 and Yocum test 21 may sometimes be positive. Positivity of these tests is caused by a painful reaction, but it may also be caused by irritation of the rotator cuff related to an internal impingement that can be associated with an anterior microinstability. In some patients, the Neer=s impingement test 22 can also be positive, mimicking subacromial impingement. The actual cause is superior and posterior translation of the humeral head, causing subacromial bursitis and injury to the bursal side of the rotator cuff (internal impingement). Tests stressing the bicipital anchor, such as the O Brien active compression test (which is best for evaluating an anterior type II SLAP), 23 crank test, 24 anterior slide test, 25 biceps

3 MINOR SHOULDER INSTABILITY 213 FIGURE 1. (A) In the Castagna test, the arm is in midabduction and rotated externally to the end position. Pain located at the posterior-superior corner of the shoulder implies a positive test. (B) The relocation maneuver. Posteriorly directed force is performed, and, if the pain is relieved, this is interpreted as a positive Castagna test. load test,26 or forced shoulder abduction and elbow flexion test,27 can be positive. Imaging studies are of little value; conventional radiographs are negative in most cases, as is magnetic resonance imaging and magnetic resonance imaging with arthrography. We propose the Castagna test for minor instability. The patient is positioned with 45 of glenohumeral abduction. The arm is maximally externally rotated. Posterior/superior pain is associated with a loose anterior joint capsule and MGHL. If pain is relieved with relocation, this represents a positive Castagna test (Fig 1A and B). The Castagna test is similar to the Jobe relocation test except that the Jobe test is performed with the arm at 90 abduction. TREATMENT Variants of the MGHL should be evaluated carefully in presence of minor shoulder instability, in particular when another associated lesion is found. An indirect sign of minor instability is the distance between the long head of the biceps and the rotator cuff. This distance increases in patients with minor shoulder instability because of the relative superior displacement of the humeral head related to insufficiency in the MGHL complex. Capsular volume can appear to be increased in these shoulders, and the drivethrough sign may be positive. In the presence of a large sublabral hole, the superior labrum should be examined carefully. If fraying and looseness are found, it is likely that traction is slowly damaging the labral insertion, thus enlarging the sublabral foramen, affecting the tension on the MGHL, and contributing to the development of minor instability. In the presence of a Buford complex and if fraying and/or detachment of the anterior biceps anchor is noted, it is likely that traction of the cordlike MGHL will stretch the biceps attachment and damage the biceps anchor. This lesion may in fact evolve to a SLAP lesion in overhead athletes. In patients with AMSI, an insufficient MGHL may be the only pathology. A stretched or loose ligament can be assessed by using the arthroscopic probe or with dynamic testing (humeral head translation and rotation). Once diagnosis of pathological condition is done, surgical treatment is recommended. Surgeons treating these lesions should have a good knowledge of capsulolabral shoulder anatomy. The type of abnormality should be well recognized and surgical treatment must be tailored to the specific injury to avoid causing a stiff shoulder. The anatomy and pathology of the superior glenoid rim have become better defined with the development of arthroscopy. Normally, in 70% of cases, the MGHL appears as a folded thickening in the anterior capsule that crosses the subscapularis tendon at the 45 angle to insert on the anterior-superior neck of the glenoid.28 Normal variants of MGHL are recognized and well described in the literature.15,16,28,29 The MGHL ligament can appear as a cordlike ligament (smooth ropelike structure) that can attach as normally at the neck of the glenoid superiorly to the anterior-superior rim or associated with a sublabral

4 214 A. CASTAGNA ET AL. hole. Sometimes, MGHL can be represented by a thin veil or it can be absent. 16 Retrospective studies have reported an incidence ranging from 8% to 18.5% for a sublabral hole and from 1.5% to 6.5% for a Buford complex. 15,16 Understanding the shift from common variants to pathological condition of the anterior-superior glenoid rim is a very demanding task even for an experienced surgeon; one should pay a special attention to this region of the shoulder, particularly when clinical history or examination is suspected for a minor instability. We believe that variants of MGHL may not be completely benign and, especially when associated with other findings such as fraying, hyperemia, stretching, and loosening can be suspect of pathological condition. Moreover, the presence of indirect pathological signs such as fraying of the posterior-superior labrum, synovitis of the posterior-superior capsule, partial tear on the articular side of the supraspinatus, or a SLAP lesion associated with previously described findings of the anterior-superior glenoid rim should alert the surgeon to the likely presence of pathological conditions of the MGHL complex. Surgical treatment can consist, in case of the absence of the MGHL, of creating a new MGHL by harvesting capsular tissue using a suture hook from the anterior capsular pouch. This tissue is shifted and plicated to the anterior labrum. In the presence of a cordlike MGHL with an associated sublabral foramen that has expanded superiorly with frayed and eroded tissues, it should be repaired directly at the injured area without reattaching the original sublabral hole to the glenoid. The associated lesions are then treated as well. Rehabilitation is required for 6 to 9 months before returning to competitive sports. Reduction in external rotation is usually permanently reduced by a few degrees. CONCLUSION Minor shoulder instability may be caused by microtrauma (AIOS) or anatomic variants combined with muscle atrophy as a result of immobilization (AMSI). The lesion involves the MGHL. An arthroscopist must distinguish between normal variants and pathological findings. When nonsurgical treatment fails, arthroscopic plication and a shift of the anterior capsule represents a MGHL reconstruction. Surgical stabilization results in resolution of primary minor shoulder instability and secondary impingement. REFERENCES 1. Matsen FA, Thomas SC, Rockwood CA. In: Rockwood CA, Matsen FA, eds. The shoulder. Philadelphia: WB Saunders, 1990: Lippitt SB, Harryman DT II, Sidles JS, Matsen FA III. Diagnosis and management of AMBRI syndrome techniques. Tech Orthop 1991;6: Rowe CR, Zarins B. Recurrent transient subluxation of the shoulder. J Bone Joint Surg Am 1984;66: Silliman JF, Hawkins RJ. Classification and physical diagnosis of instability of the shoulder. Clin Orthop 1993;291: Burkhart SS, Morgan CD, Kibler WB. Shoulder injuries in overhead athletes. The dead arm revisited. Clin Sports Med 2000;19: Castagna A. Arthroscopic findings in shoulder instability (abstract). Presented at the 15th annual San Diego Shoulder meeting, 1997, San Diego, CA. 7. Castagna A, Grasso A, Vinanti G. Minor shoulder instability. In: Lajtai G, Snyder SJ, Applegate GR, Aitzmuller G, Gerber C, eds. Shoulder arthroscopy and MRI technique. Berlin: Springer-Verlag, 2003: Townley C. The capsular mechanism in recurrent dislocation of the shoulder. J Bone Joint Surg Am 1950;32: Andrews J, Carson WJ, McLeod W. Glenoid labrum tears related to the long head of biceps. Am J Sports Med 1985;13: Harryman DT, Sidles JA, Clark JM, McQuade KJ, Gibb TD, Matsen FA. Translation of the humeral head on the glenoid with passive glenohumeral motion. J Bone Joint Surg Am 1990;72: Jobe CM. Posterior superior glenoid impingement: Expanded spectrum. Arthroscopy 1995;11: Walch G, Boileau P, Noel E, et al. Impingement of the deep surface of the supraspinatus tendon or the posterior superior glenoid rim: An arthroscopic study. J Shoulder Elbow Surg 1992;1: Savoie FH, Papendik L, Field LD, Jobe C. Straight anterior instability: Lesions of the middle glenohumeral ligament. Arthroscopy 2001;17: Burkhart SS, Morgan CD. Technical note. The peel back mechanism: Its role in producing and extending posterior type II SLAP lesion and its effect on SLAP repair rehabilitation. Arthroscopy 1998;14: Williams MM, Snyder SJ, Buford D Jr. The Buford complexthe cord-like middle glenohumeral ligament and absent anterosuperior labrum complex: A normal anatomic capsulolabral variant. Arthroscopy 1994;10: Ilahi OA, Labbe MR, Cosculluela P. Variants of the anterosuperior glenoid labrum and associated pathology. Arthroscopy 2002;18: Rao AG, Kim TK, Chronopoulos E, McFarland EG. Anatomical variants in the anterosuperior aspect of the glenoid labrum: A statistical analysis of seventy-three cases. J Bone Joint Surg Am 2003;85: Steinbeck J, Liljenqvist U, Jerosch J. The anatomy of the glenohumeral ligamentous complex and its contribution to anterior shoulder stability. J Shoulder Elbow Surg 1998;7: Jobe FW, Jobe CM. Painful athletic injuries of the shoulder. Clin Orthop Relat Res 1983;173: Burns WC II, Whipple TL. Anatomic relationship in the shoulder impingement syndrome. Clin Orthop Relat Res 1993;294: Yocum LA. Assessing the shoulder. History, physical examination, differential diagnosis, and special test used. Clin Sports Med 1983;2: Neer CS II. Anterior acromioplasty for the chronic impinge-

5 MINOR SHOULDER INSTABILITY 215 ment syndrome in the shoulder: A preliminary report. J Bone Joint Surg Am 1972;54: O Brien SJ, Pagnani MG, Fealy S, McGlynn SR, Wilson JB. The active compression test: A new and effective test for diagnosing labral tears and acromioclavicular joint abnormality. Am J Sports Med 1998;26: Liu SH, Henry MH, Nuccion SL. A prospective evaluation of a new physical examination in predicting glenoid labral tears. Am J Sports Med 1996;24: Kibler WB. Specificity and sensitivity of the anterior slide test in throwing athletes with superior glenoid labral tears. Arthroscopy 1995;11: Kim SH, Ha KI, Han KY. Biceps load test: A clinical test for superior labrum anterior and posterior lesions in shoulders with recurrent anterior dislocations. Am J Sports Med 1999;27: Nakagawa S, Yoneda M, Hayashida K, Obata M, Fukushima S, Miyazaki Y. Forced shoulder abduction and elbow flexion test: A new simple clinical test to detect superior labral injury in the throwing shoulder. Arthroscopy 2005; 21: Snyder SJ. Diagnostic arthroscopy. In: Snyder SJ II, ed. Shoulder arthroscopy. Philadelphia: Lippincott Williams and Wilkins; 2003: Morgan CD, Rames RD, Snyder SJ. Arthroscopic assessment of anatomic variations of the glenohumeral ligaments associated with recurrent anterior shoulder instability. Orthop Trans 1992;16: