Impingement of the deep surface of the supraspinatus tendon on the posterosuperior glenoid rim: An arthroscopic study

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1 Impingement of the deep surface of the supraspinatus tendon on the posterosuperior glenoid rim: An arthroscopic study G. Walch, MD, P. Boileau, MD, E. Noel, MD, and S. T. Donell, MD, Lyon, France Seventeen athletes presenting with unexplained shoulder pain on throwing underwent arthroscopic examination. All but one practiced a throwing sport. The dominant arm was involved in all patients except one bodybuilder. Their mean age was 25 years (range 75 to 30 years), and they had symptoms present for a mean of27 months. None had clinical, radiologic, or arthrascopic evidence of anterior instability. Preoperative clinical examination typically revealed localized pain on full external rotation and 90 abduction, signs ofrupture ofthe rotator cuff, and positive impingement sign. In 70 cases computed tomographic arthrogram showed evidence of abnormality at the posterior edge of the glenoid. The mean humeral retrotorsion was 70 (range 5 to 30 ). Under arthroscopy, with the arm placed in full external rotation and 90 abduction (the throwing position), impingement was found between the posterosuperior border of the glenoid and the undersurface of the tendinous insertions of supraspinatus and infraspinatus. A partial rupture of the cuff, which was demonstrated by arthrogram, was confirmed in eight patients, whereas a partial capsulotendinous rupture, which was not demonstrated by arthrogram, was seen in nine patients. Twelve patients had further lesions of the posterosuperior labrum. This study suggests that in addition to Neer's "impingement syndrome" and lobe's "instability with secondary impingement," impingement ofthe undersurface of the cuff on the posterosuperior glenoid labrum may be a cause of painful structural disease ofthe shoulder in the thrower. (J SHOULDER ELBOW SURG 7992; 7: ) Shoulder pain frequently occurs in athletes who practice throwing sports and has already led to numerous publications. There are three theories as to the origin of the pain and its pathogenesis: the subacromial impingement syndrome.': instability with secondary impingement/ and excessive traction on the tendons and capsuloligamentous structures during exercise.': 15 However, all pain is not explained by these three hypotheses, and we think that there is an additional explcnotion." Such a potential explanation was found on arthroscopic observation of the most painful position in 90 From the Centre Hospitalier Lyon-Sud, Lyon, France. Reprint requests: G. Walch, MD, C1inique de Chirurgie Orthopedique et Traumatalogique [Pr Dejour], Centre Hospitolier Lyon-Sud, F Pierre Benite, France. 32/ abduction and full external rotation. It is the purpose of this article to document these findings. PATIENTS AND METHODS Between December 1, 1989, and June 30, 1991, 30 athletes were examined arthroscopically for pain in the shoulder. This pain was specifically related to the throwing position. No clinical evidence of anterior instability was detected. Thirteen athletes were found to have Bankart lesions or SLAP* lesions and are not included in this series. Seventeen patients had no evidenceof anterior instability, and they constitute the base of this study. All but one were throwers (Table I). There were 11 men and six women with a mean age of 25 years (range 15 'Superior labrum, both anterior and posterior. 238

2 Volume 1 Number 5 Impingement of deep surface of supraspinatus tendon 239 to 30 years). The dominant arm was affected in all the throwers, except one bodybuilder, whose nondominant arm was affected. All patients complained that diffuse shoulder pain was worse in the posterior part of the shoulder. In 10 cases the pain disappeared when the patient stopped playing the sport but returned every time the patient resumed playing. In seven cases the pa in became permanent, preventing sleep and affecting everyday activities. No patient presented with dislocation, subluxation, or the sensation of instability in the shoulder. The mean duration from the onset of symptoms to presentation was 27 months (range 12 to 60 months). All the patients had received nonoperative therapy to some extent. This therapy included nonsteroidal antiinflammatory drugs, physiotherapy, rest, and local injections. All patients had a rad iographic work-up consisting of anteroposterior plain radiographs in neutral, external, and internal rotation, a lateral view of the glenoid,3 a contrast arthrogram, and a computed tomographic arthrogram. One patient underwent magnetic resonance imagingand ultrasonography instead of arthrography. All patients underwent arthroscopy under general anesthesia. The patients were placed in the lateral decubitus position with the arm in vertical and horizontal double traction." The arthroscope was introduced through a routine posterior portal. A probe was introduced through an anterior portal to confirm the absence of a Bankart lesion. After routine diagnostic arthroscopy was performed the traction was removed, and the arm was placed in full external rotation and was examined in varying degrees of abduction. RESULTS Clinical examination. The data for the clinical examination are outlined in Table II. Examination typ ically produced pa in when the arm was held in full external rotation and was then moved between 90 and 150 abduction. There was usually evidence of a rotator cuff problem, notably involving the supraspinatus (impingement sign, supraspinatus weakness). External rotation at 90 abduction had a mean value of 104 (range 92 to 115 ). In four patients external rotation on the affected side averaged 15 more than on the normal opposite side. Atrophy in the supraspinatus and infraspinatus Table I Main sport practiced by patient Sport I No. of patients Tennis" Volleyball " Handball Javel in Bodybuilder One pat ient played both tennis and volleyball compet i tively. fossae was never found. Two patients demonstrated a positive sulcus sign bilaterally but showed no evidence of shoulder instability. Imaging studies. Table III outlines the results of the imaging studies. There was an abnormality on conventional radiography in 14 cases. In five cases the greater tuberosity had cysts (Fig. 1) or sclerosis w ith microcysts, as can be found with degenerative rotator cuff tea rs. In one case, on the lateral glenoid view, an osteophyte was noted on the posterior border of the glenoid fossa (Fig. 2). The plain radiographs were completely normal in only three cases. Single contrast radiography was routinely performed preoperatively in those patients who had signs of supraspinatus damage. The arthrogram was positive in eight cases, showing broaching of the deep surface of the supraspinatus tendon and leakage of contrast into its substance. The contrast was shaped like either a flame or a cloud (Fig. 3). There was never communication with the subacromial bursa. No significant difference in age existed between the patients with a partial rupture (26 years) and those without (24 years). The computed tomographic scan was obta ined immediately after the arthrogram and had three objectives; to check the integrity of the labrum-inferior glenohumeral ligament complex, to analyze the posterior border of the glenoid, and to measure humeral retrotorsion by tak ing supracondylar cuts. No patient had an anterior lesion. However, 10 patients had bony changes at the posterosuperior part of the glenoid. These changes included obvious small osteophytes, slight sclerosis or rounding of the rim, or wearing down of the posterosuperior labrum (Fig. 4). Humeral retrotorsion was measured from the periphery of the articular cartilage that forms the anatomic neck. With this site as a landmark the normal value lies between 25 and The

3 240 Walch et al. J. Shoulder Elbow Surg. September/October 1992 Table II Clinical findings Test Active flexion Passive external rotation Impingement sign (Neer) Modified impingement sign (Hawkins) Supraspinatus strength (Jobe) Infraspinatus strength in 90 abduction Apprehension test Relocation test (Jobe) Result Symmetric Equal Increased Pathologic (painful) Pathologic (painful) Normal but painful Decreased strength Normal Normal but painful No apprehension but painful Positive No Table III Radiologic examination Plain x-ray films Contrast arthrography Computed tomographic arthrogram Findings Posterosuperior humeral head geode Sclerosis or microcysts of tuberosity Abnormal posterior border of glenoid Normal Rupture of deep surface of supraspinatus Normal Abnormality of posterosuperior glenoid edge Mean humeral retrotorsion No. of patients (range -5 _30 ) mean angle in this series was 10 0 (range - 50 to 30 0 ), clearly much lower than normal. Arthroscopic findings. The arthroscopic findings were recorded on videotape and are presented in Table IV. No patient had a lesion of the inferior glenohumeral ligament-labrum complex or had a lesion of the subscapularis and biceps tendon. No synovitis was recorded. All patients demonstrated impingement between the posterosuperior edge of the glenoid and the insertion of the rotator cuff when the arm was placed in the throwing position (Fig. 5). Contact occurred between 90 0 and abduction on the area between 9 o'clock and 11 o'clock on the posterior edge of the glenoid. The labral lesions appeared similar to degenerative types, with irregular scuffing and small flap tears that could lie within the joint. In two cases the lesion extended toward the superior labrum, but they never extended in front of the insertion of biceps. In eight cases an osteochondral lesion of the humeral head was found. This was situated higher than the classic Hill-Sachs lesion and either was adjacent to the posterior sulcus or was more distal and separated by a strip of normal cartilage. It was always less than 1 cm in size and only a few millimeters in depth. It could correspond to humeral impaction on the posterosuperior part of the glenoid. However, it was never possible to demonstrate this impact at arthroscopy. Most cuff lesions affected the supraspinatus. Five cases were Ellrnonrr' grade I and eight cases were grade II or III, the latter being difficult to differentiate, because some tears extended into the depth of the tendon and dissected it into two layers. DISCUSSION This study has described arthroscopically confirmed impingement of the deep surface of the rotator cuff on the posterosuperior border of the glenoid while the arm was placed in the position of abduction and external rotation. Our findings suggest that this impingement

4 Volume 1 Number 5 Impingement of deep surface of supraspinatus tendon 241 Figure 1 Plain x-roy film shows geode (area of sclerosis) in tuberosity. Figure 2 Plain x-roy film shows posterior glenoid osteophyte. could have caused the observed lesions of the supraspinatus, the posterior labrum, and the posterior glenoid rim. No other mechanism can exploin the combination of these lesions. Perry" stressed that this contact could occur during the "cocking" phase, but did not state whether the contact was physiological or pathologic or whether it could give rise to lesions. More recently Jobes showed in a study of frozen cadaveric shoulders that the tendinous insertion of the rotator cuff became jammed between the humeral head and the glenoid when the arm was placed in the throwing position. We have seen this arthroscopically in patients who had no cuff symptoms or intraarticular disease and who were not athletes in throwing sports. It seems probable that the contact is, in fact, physiological and can be found to varying degrees in healthy subjects, and only repetitive hard throwing can produce the disease. Excessive external rotation does not appear to be an important cause of this impingement, because it was increased in only four patients when it was compared with the contralateral side. Only two of patients had evidence of hyperlaxity by having a positive sulcus sign. Measurement of humeral retrotorsion is still the subject of much discussion. The upper humeral landmark can be the line of insertion of the capsule on the humeral neck," or it can be the articular margin10 as chosen here. There is no doubt that the average angle in this series was low and therefore could be a contributing factor in impingement. However, two of our patients had normal angles and still had symptoms. Cause of the cuff lesions. Radiography must be performed by a radiologist who is familiar with the technique for demonstrating cuff lesions. Two of our patients had normal initial arthrograms, but their shoulders had not been manipulated after injection of contrast material. Cuff lesions were demonstrated on a second arthrogram that was correctly performed. After injection the shoulder must be actively mobilized through abduction and adduction, and

5 242 Walch et al. J. Shoulder Elbow Surg. September/October 1992 Figure 3 Arthrogram showing partial rupture of undersurface of supraspinatus. Flamelike (A) and cloud like (8) leakage of contrast material in substance of tendon. Figure 4 Change in contour and sclerosis of posterior glenoid rim on computed tomographic arthrogram.

6 Volume 7 Number 5 Impingement of deep surface of supraspinatus tendon 243 Figure 5 Schematic representation (A) and magnetic resonance image (8) of posterosuperior glenoid impingement between posterior edge of glenoid and deep surface of supraspinatus and infraspinatus tendons. then traction must be applied in the axis of the arm. Leakage of contrast into the supraspinatus may be minimal and must be looked for at the level of the greater tuberosity. In eight of our patients contrast material ran into the substance of the supraspinatus tendon on arthrography. Five had a localized disruption of the capsule that exposed the undersurface of the fibers to a depth of 3 mm, which was not demonstrable arthrographically. Four patients had only fraying of the capsule. We agree with Ellrnonrr' that simple capsular tears do not constitute a true cuff rupture, because they frequently are found in patients over 50 years old. However, in young subjects they are much rarer, and as Snyder et al. ' 9 suggest, they are clearly traumatic and are not degenerative in origin. Rotator cuff lesions have been described as either tendinitis (Neer grade II) or partial/total ruptures (Neer grade III). Many authors cite subacromial impingement as the reason these lesions occur, even if the superficial fibers of the tendon are infect.': '4. 16 Therefore the standard treatment is anterior acromioplasty or division of the coracoacromial ligament. But Tibone et al. 20 found this release insufficient because only 22% of their throwing athletes Table IV Arthroscopic findings Findings No. of patients Posterosuperior glenoid impingement of rotator cuff, arm in throwing position Posterosuperior labrallesion 12 Osteochondral fracture of humeral 8 head Cuff lesions (Ellmann classification) Supraspinatus Grade I 3 Grade II/III 7 Infraspinatus Grade I 2 Grade II/III 1 returned to the same sporting level afterward. This is similar to our experience. The condition of throwing athletes is improved by an anterior acromioplasty, but this never cures the athletes of pain when they are throwing and does not explain why they fail to return to performing at the highest level. Because of this, Jobe et ol." proposed the theory that the impingement is secondary to anterior instability in throwing athletes. The cuff lesions are said to occur when the anteriorly

7 244 Walch et Shoulder Elbow Surg. September/October 1992 subluxated humeral head compromises the tendons under the acromial arch while the arm is cocked. Because none of our patients had any evidence of anterior instability, this mechanism is not likely to apply to them. Furthermore, in the throwing position the greater tuberosity lies posterior and distal to the acromial arch, and it is impossible for the cuff tendons to become trapped when the head is subluxated anteriorly. The positive relocation sign found in all our patients can be explained by the fact that pushing the humeral head posteriorly stops it from impinging on the posterior part of the glenoid. Andrews et ol.' believed that the lesions occur from excessive traction repeated thousands of times on the rotator cuff. This hypothesis is very plausible, except that it does not explain why the subscapularis, which is in exactly the same mechanical environment, is so rarely involved. Uhthoff et ol." and Yamanaka and Fukuda" thought that progressive degeneration of the tendinous fibers on the deep surface causes partial rupture at this site. This was based on histologic studies that appear most likely to have been performed on adults over 50 years old. This mechanism cannot explain the cause of the tears in athletes under 30 years old. Our hypothesis is that the lesions on the undersurface of the cuff are the result of impingement on the posterior edge of the glenoid when the arm is in the throwing position. This impingement is probably physiological, but in throwing athletes the repetitive nature of the sport on their dominant arm leads to mechanical damage and the lesions observed. Cause of the posterior labral and glenoid lesions. In 1977 Lombardo et ol." reported four cases of posterior glenoid lesions in professional pitchers who needed surgical debridement of the posterior part of the joint. They suggested the lesions were the result of excessive traction on the posterior capsule during the final phase of throwing. In 1978 Barnes and Tullos' also described posterior glenoid lesions in eight baseball players. They called these Bennett's lesions after the radiologist who first described them. The lesions were posteroinferior glenoid subperiosteal osteophytes that were often associated with a tear of the glenoid labrum. The authors thought that these lesions were either a sequela of capsular tears or a result of previously undetected posterior humeral subluxation. It seems that the lesions seen on computed tomographic arthrogram in this study are a combination of those described by Barnes and Tullos" and Lombardo et ol." More recently, Snyder et ol." have reported posterior labral lesions associated with lesions of the humeral head. They attributed these lesions to a single violent traumatic event that caused "a combination of compression force on the superior joint surface and a proximal subluxation force on the humeral head." None of our patients had a clear traumatic event, and none had labral lesions of the SLAP 1 type that extended anterosuperiorly in front of the insertion of the long head of biceps. However, the lesions produced from trauma between the humeral head and the glenoid, as reported by Snyder et ol.," are very similar in appearance to those seen arthroscopically in this series. It is possible that some SLAP lesions may be caused by posterosuperior impingement. To conclude, dynamic arthroscopic visualization of the shoulder in full external rotation and varying degrees of abduction has suggested a new idea as to the cause of well-known lesions of the rotator cuff and posterior border of the glenoid in throwing athletes. Further clinical and radiologic studies are needed to define the role of humeral retrotorsion in the cause of this condition. REFERENCES 1. Andrews JR, Broussard T5, Carson WG. Arthroscopy of the shoulder in the monagement of partial tears of the rotator cuff: a preliminary report. Arthroscopy 1985; 1: Barnes DA. Tullos HS. An analysis of 100 symptomatic baseball players. Am J Sports Med 1978;6: Bernageau J, Debeyre J, Ferrone J. Interet du prolil qlenoidien dans les luxations recidivontes de l'epoule. Rev Chir Orthop 1976;62(supplll): Ellmann H. Diagnosis and treatment of incomplete rotator cuff tears. Clin Orthop 1990;254: Gartsman GM. Arthroscopic acromioplasty far lesions of the rotator cuff. J Bone Joint Surg [Am] 1990;72: Gross RM, Fitzgibbons TC. Shoulder arthroscopy: a modified approach. Arthroscopy 1985; 1: Hawkins RJ, Kennedy Jc. Impingement syndrome in athletes. Am J Sports Med 1980;8: Jobe CM. Evidence far superiar glenoid impingement on the rotator cuff. Personal communication at the 4th Congress of the European Society of the Shoulder and Elbow Surgery, Milan, Italy, October Jobe FW, Tibone JE, Jobe CM, Kvitne RS. The shoulder in sports. In: Rockwood CA, Matsen FA, eds. The shoulder, vol 2. Philadelphia: Sounders Co, 1990: Kronberg M, Brostrom LA. Soderlund V. Retroversion of

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