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Posterior superior glenoid impingement: Expanded spectrum
Posterior Superior Glenoid Impingement: Expanded Spectrum Christopher M. Jobe, M.D.
Summary: Posterior superior glenoid impingement is a recently recognized mechanism of injury producing rotator cuff injury in athletes. Usually the mechanism is repetitive overhand activity such as throwing. A survey of the author’s practice was undertaken to show a wider spectrum of this mechanism both in the activity that caused it and the number of structures at risk of injury from this mechanism. The survey revealed 11 patients who had a clear recollection of their mechanism of injury and an objective documentation of the injury by arthroscopy or imaging studies. The majority of shoulders had damage to more than one of the five structures at risk from this mechanism of injury. Six caseswere not sports related. Glenoid impingement may injure one or more of the following: (1) superior labrum, (2) rotator cuff tendon, (3) greater tuberosity, (4) inferior glenohumeral ligament or labrum, and (5) superior glenoid bone. Injury to more than one structure may be the rule and injury to one structure may indicate investigation of the other four. Key Words: Rotator cuff injury-Labrum injury-Glenoid-Impingement syndrome-Shoulder instability-Mechanism of injury.
T
he source of rotator cuff damage and symptoms continues to be an area of controversy and a fertile area for discussion. It has been shown previously that within the glenohumeral joint, it is possible for the rotator cuff and adjacent greater tuberosity to make contact with the posterior superior glenoid and labrum.‘” Indeed, Walch et aL3 have presented a series of athletic patients showing that this contact can lead to pathology within the glenohumeral joint. To date, descriptions of posterior superior glenoid impingement identify athletic individuals where a repetitive throwing-like motion, causes shoulder pain, and physical findings suggesting impingement syndrome.‘,3 The relocation test can produce a physical finding that is helpful in distinguishing this entity from subacromial impingement. Pain rather than apprehension produced in 90” of abduction, hyperextension, and From the Department of versity School of Medicine, Address correspondence Jobe, M.D., Department of versity School of Medicine, Linda, CA 92350, U.S.A. 0 1995 by the Arthroscopy
Orthopaedic Surgery, Loma Linda UniLoma Linda, Calllfornia, U.S.A. and reprint requests to Christopher M. Orthopaedic Surgery, Loma Linda Uni11234 Anderson St, Rm. A519, Loma Association
of North
America
0749-8063/95/1105-1208$3.00/O
530
Arthroscopy:
The Journal
of Arthroscopic
external rotation is relieved by posteriorly directed pressure on the proximal humerus.’ The current interpretation of the relocation test is that the eliciting phase of the test creates impingement between the greater tuberosity and rotator cuff, and the posterior superior glenoid and labrum and creates the pain. Translating the humeral head posteriorly alleviates this pressure. Posterior superior glenoid impingement is felt to be the most frequent cause of rotator cuff disease seen in athletes often in association with anterior instability.’ A curious facet of the relocation test and the impingement seen on arthroscopy is that it has been reported only in athletic individuals with minor degrees of instability or no instability. A patient with a large subluxation or true dislocation would seem to be protected from making this kind of contact.“3 Increased attention to this mechanism of injury has brought out a larger spectrum of conditions arising by the same mechanism of injury. The conditions under which these injuries occur are not necessarily athletic, nor are they typical of the throwing motion. In some cases, the diagnosis has depended on extra effort in obtaining the history of the exact mechanism of injury. It is the purpose of this article to present a series of patients who demonstrate the larger spectrum of injury
and Related Surgery,
Vol 11, No 5 (October),
1995: pp 530-536
SUPERIOR
GLENOID
IMPINGEMENT:
TABLE 1. Posterior Superior Glenoid Pt. No.
9
Sex
F
Age
Occupation work
Work Related
Yes
Mechanism Injury
Structures
Road
43
Clerical
No
20
Student
No
50
Obstetrician
No
34
Dermatologist
No
55
Laborer
Yes
44
Stenographer
No
30
Homemaker
No
26
Laborer
Yes
22
PT student
No
Acute
43
Forklift
Yes
Chronic; abd ext rot position most of work day
Part cuff tear Chondromalacia postsup head Sup labral laxity Post sup cuff part tear jt side Labral changes
Chronic; sleeps on fully elevated arm Acute; dove from a height into water. Arms directly overhead. Acute; abd. ~90” ext rotation
Sup lab detached biceps (SLAP)
NOTE. Except for where a SLAP lesion is noted and adjacent synovium, and adventitial scar.
abd-ext
rot
Diagnosed by Dx. Made
Treatment Ant
capsulolabral reconst.
Outcome
Arthroscopy
Improved; return
didn’t to work
Rehab cuff serratus
&
Arthroscopy
Improved (nearly complete relief)
Joint side cuff damage Sup lab damage
Rehab cuff serratus
&
Arthroscopy
Complete
Fx tuberosity
Rest & rehab
Radiograph
Incomplete
Fx tuberosity
Rest
Complete
Inner cuff tear Deformed sup labrum (bursa entirely normal)
Arthroscopic debridem of tear for visualization then rehab Arthroscopic reattachment
MRI (not seen on radiograph) Arthroscopy
Compl Bankart
WI
cuff tear lesion
Part cuff tear Labral deform Chondromalacia adjacent to cuff
Bucket-handle Bankart lesion Part cuff tear
Labral Inside
AND METHODS
Eleven patients from the author’s practice fulfilled the following criteria: first, the patients had a clear
SLAP
deform cuff tear
(pt. 7 & 10) the labral
resulting from this mechanism. The larger spectrum refers not only to the larger number of activities that lead to injury but to the number of tissues at risk.
MATERIALS
Injured
Acute; moving wet sand bags; abduction ~90 ext rot Chronic; throwing (as a youth & as little league coach) Acute; fall from bicycle w/arm elev Acute; slipped on skateboard, violent active elevation Acute; slipped skiing violet active elev Acute; shoveling inj abd ext rot
531
Expanded Spectrum
of
36
driver
Impingement:
SPECTRUM
changes
consist
& rehab
Arthroscopy
relief
relief
relief
Relief of cuff pain; did not return to work secondary to other injuries Compl relief until reinj by falling object Restoration of active ROM; still has apprehens sign
Open cuff repair
MRI
Arthroscopic acromioplasty w/poor result then, revision of rehab program Arthroscopic exe of upper lab fragment Open ant capsulolabral recon. Rehab &job mod
Arthroscopy
Nearly complete relief; has returned to work
Arthroscopy
Complete
Arthroscopy
Relief achieved by change in job
of a change
in shape,
injected
appearance
relief
of labrum
recollection of their mechanism of injury: full elevation or abduction external rotation (Table 1). Patients with pathology but no clear recollection of their mechanism of injury were excluded. Second, on arthroscopic or radiographic examination, there was injury to one or more of the following five tissues: the inner surface of the rotator cuff, the posterior-superior labrum, the inferior glenohumeral ligament labrum complex, the
532
c. M. JOBE
FIG 1. Photograph and sketch of a cadaver specimen with the arm in full elevation shows the five structures prone to injury by this mechanism: (1) greater tuberosity, (2) rotator cuff tendon, (3) superior labrum, (4) inferior glenohumeral ligament and labrum loaded in tension, and (5) superior glenoid bone. The inferior glenohumeral ligament is loaded in tension, the other four in compression.
greater tuberosity, or the bone of the superior glenoid (Fig 1). Patients with other pathology such as calcific tendinitis and subacromial pathology were excluded. Also excluded by these criteria would be patients who responded to a rehabilitation program early on and would therefore not undergo arthroscopy. As this study clarified the diagnostic spectrum, the rehabilitation protocol before surgery has been altered. Under the current approach, there is a more extensive trial of rehabilitation that would have probably eliminated the need for arthroscopy in patients 2, 3, and 5. RESULTS History Recognition of the mechanism of injury usually depended on the patients recall but in at least one case (patient 11) required reeducation of the physician as to the exact nature of the patient’s work. Patient 11, a forklift driver, went unrecognized at
arthroscopy partly because he did not fit the prevailing pattern of the supraglenoid impingement patient at the time (i.e., he was not a thrower), and because his surgeon did not understand how a forklift is driven. The surgeon thought that forklifts were driven in the same manner as automobiles. An elevation or abduction external rotation injury seemed highly unlikely at the time of surgery as a cause of rotator cuff damage. The patient, after specific questioning about the nature of his activities, was better able to explain his mechanism of injury. Because loads are stacked so high, forklift drivers cannot see over them. To drive safely, the patient and other forklift drivers spend 80% of their time driving backwards looking over the opposite shoulder (Fig 2). This has been confirmed by the warehouse manager at Loma Linda University. Physical Findings Seven of the patients had positive relocation test results. The two patients (patients 4 and 5) with greater
SUPERIOR
GLENOID
IMPINGEMENT:
SPECTRUM
533
shows a wider spectrum of pathology resulting from this mechanism than has been discussed in the past.
Mechanism
FIG 2. The position in which patient 11 spent the majority of his working day. To drive safely, he and other forklift drivers must drive in reverse putting at least one shoulder into the abducted externally rotated position. Fatigue of the upward rotators of the scapula would cause the driver to rest the glenohumeral joint in the impinged position. Some drivers place the opposite arm, the right arm in this illustration, into abduction-external rotation. They do this so they can use the right hand on the frame to assist with rotating the torso. This second position would place both shoulders at risk.
tuberosity fractures could not be tested secondary to pain. Patients 8 and 10 with Bankart lesions experienced apprehension before achieving the position of the relocation test.
Injury
to Specific Structures
Damage to one or more of the structures at risk was found in all patients. Of the eight patients who underwent arthroscopy, seven had damage to more than one structure (3 patients with 3 structures injured, 4 patients with 2). As the two tuberosity fractures were diagnosed by other means, soft tissue injury would not have been revealed. No patient was found with fracture of the superior glenoid.
DISCUSSION This mechanism of injury as a source of rotator cuff damage has come to light only recently, but had been mentioned previously by Codman as a cause of greater tuberosity fracture (Fig 3). This series of patients
of Injury
and Tissues at Risk
The glenohumeral joint has been found to function basically as a ball and socket joint, with a relatively steady center of rotation with small translations at extremes of motion.5 Definition of the terms describing motion is in order. As with any ball and socket joint, the spinning type of motion, i.e., motion where the center of the ball does not move relative to the socket, can be subdivided with respect to an axis of the ball into angulation and rotation (Fig 4). The two most important axes of the glenohumeral joint are the axis of the shaft, which has a boney representation and is, therefore, most useful for clinical and kinesiologic purposes, and the axis of the articular cartilage, which is the true “axis of the joint” but unfortunately has no boney representation. Angulation is motion of an axis relative to the glenoid and rotation is motion about that axis. In angulation, there tends to be at the extreme a slight translation in the same direction as the capsule opposite the angulation tightening. Tissues at the edges of the articular cartilage in the direction of angulation will approach each other and make contact. The mechanism of injury we are discussing here represents an angulation either directly superiorly, elevation as in Neer’s test for impingement, or posterior superiorly, abduction-external rotation as in throwing. This extreme angulation places five different structures at risk: (1) the inferior glenohumeral ligament and labrum, (2) the rotator cuff, (3) the posterior superior labrum, (4) the greater tuberosity, and (5) the bone of the superior glenoid. The angulation of the joint is limited by the inferior glenohumeral ligament, and increased angulation beyond the normal range will result in stretch of the ligament and/or its labral insertion. Compression stresses occur in the superior glenoid labrum, the inner fibers of the rotator cuff, the bone of the greater tuberosity, and the bone beneath the labrums The inferior glenohumeral ligament is, in these two positions, draped over the prominence of the articular surface of the humeral head (Fig 1). The fibers at the apex of this bulge will bear the highest stress, with a decrease in stress as one moves away from the apex of the bulge. Stretch of these fibers at the apex of the bulge will allow an increase in angulation. Continued angulation loads will result in stretch of adjacent fibers, and can eventually lead to an increase in translation or minor grades of anterior subluxation as noted earlier.’
C. M. JOBE
534
d FIG 3. Codman’s concept of how the greater tuberosity fracture occurs by impingement against the glenoid. Note the resemblance to Fig 1. (The letters “b” and “d” are Codman’s designation.) (Reprinted with permission?)
The rotator cuff in this position finds its innermost or articular side fibers compressed against the glenoid labrum. The normal course of these cuff fibers contouring the humeral head is reversed so that the cuff approaches the greater tuberosity at an angle 90” different from that at rest. In addition, a reversed curve occurs in the fibers of the cuff with the inner fibers
now on the convexity while they are on the concavity at rest. The compression of the inner fibers as well as the shear stresses arising within the tendon secondary to this reversed angle of approach may result in a partial cuff tear. There is a gradation between minor and major changes. A minor change in the rotator cuff such as a small “rim rent” or an incomplete tear that leaves the majority of the tendon intact may mislead the surgeon into believing there is a subacromial problem. In fact, it is glenohumeral angulation that needs to be controlled, either by physical rehabilitation or by anterior capsular repair.’ It is conceivable that additional tearing into the substance of the tendon may affect the ability of the rotator cuff to function. In these cases, there could develop rotator cuff dysfunction as well as hyperangulation: in other words, subacromial impingement on top of glenoid impingement. The labrum in this type of injury is deformed by its contact with the inner rotator cuff and greater tuberosity. In this tissue, too, there are gradations of injury. The injury may, in minor cases, present as deformity of the labrum or build-up of adventitial scar tissue, in which case a simple debridement and a correction of the glenohumeral mechanics should alleviate the problem. The higher grade injury is a SLAP lesion, which may require surgical excision of unstable labrum or a surgical reattachment of the labrum and contiguous biceps origin.@ The bone of the humeral head, particularly the greater tuberosity, is brought against a sharp angle of the glenoid and labrum by this mechanism of injury.4 It is worth mentioning that in the author’s practice, these are the only two tuberosity fractures that occurred by this mechanism. Minor grades of damage may consist of trabecular fractures that are seen only on magnetic resonance imaging or arthroscopy. The next higher grade of injury would be a nondisplaced greater tuberosity fracture, which would require appropriate immobilization and rehabilitation. The highest grade of tuberosity injury would be a displaced tuberosity fracture requiring surgical correction. The fifth tissue at risk is the bone of the superior glenoid. No patients with this injury were found in this series. However, there are two patients with superior glenoid fractures reported by Iannotti and Wang.6 The injury in these two patients occurred by a chronic throwing type mechanism in two recreational athletes. Fatigue fractures of the superior glenoid occurred with superior labmm and biceps origin injuries in both patients. Both patients would have met the inclusion criteria for this series. Walch et aL3 also report stress changes in the sublabral bone visible on computed tomography.
SUPERIOR
GLENOID
IMPINGEMENT:
SPECTRUM
535
FIG 4. Angulation and rotation with respect to the two most important axes of the glenohumeral joint: (A) the axis of the humeral articular cartilage “the axis of the joint” and (B) the axis of the shaft “the clinical axis.” Angulation of an axis is change of its orientation to the glenoid. Rotation is movement about the axis. In this drawing the “joint axis” is perpendicular to the glenoid while the shaft is in 45” of abduction.
Combination
Injuries
The question rises that if these five tissues are at risk from the same mechanism of injury, might combinations of injuries not occur. This series of patients points out that combination injuries may be the rule rather than the exception. Eight of the 11 patients had damage to more than one structure documented. Many patients with a partial rotator cuff tear have an anterior instability that requires surgical approach to the instability even though the rotator cuff tear is minor.’ The classic combination of dislocation with rotator cuff tear seen in the older patients may also occur in the younger patients (patient S).4 It is to be pointed out that one of the patients with a tuberosity fracture shown by radiography has continued shoulder pain even after healing of the fracture, leading one to believe that if arthroscopy had been performed, injury to rotator cuff, labrum, or anterior capsule might have been seen. One should not be surprised to find a SLAP lesion concomitantly with a rotator cuff tear or humeral head fracture. In fact, Randelli et a1.7 have reported on a group of 12 young athletes with SLAP lesions and a high frequency of partial rotator cuff tear, humeral damage, or subluxation. We have, in this small series, only one subject (patient 10) who had a SLAP lesion in combination with a Bankart lesion anteriorly. This SLAP lesion was so significant that it altered the pa-
tient’s symptoms, confusing the clinical picture. By the stated mechanism of injury and apprehension test, the patient should have had an anterior instability. But by her history of recurrent instability episodes and the maneuvers by which she reduced her shoulder, she ought to have had a posterior instability. (This patient is a physical therapy student and was able to give very reliable information on reduction techniques). It was only by arthroscopy that we were able to discover that she had two lesions, a traumatic anterior instability (i.e., Bankart lesion) and a significant bucket-handle type SLAP lesion that was mimicking a posterior instability. Given the appropriate injury history, the existence of one of these injuries should trigger a more careful examination of the other four structures.
Implications
for Treatment
Treatment of these individuals is often twofold. First it is aimed at the mechanism of injury by eliminating too much elevation or abduction external rotation by exercise or surgery, and second, many times the treatment must also be aimed at the injured structure. All patients except for the two physicians with tuberosity fractures underwent strengthening of the rotator cuff to control the glenohumeral joint and strengthening of the scapular rotators to decrease the glenohumeral angulation necessary to place the arm in elevation or
C. M. JOBE
abduction external rotation. Patients who fail with this treatment and those with dislocation require a repair of the anterior capsule and labrum to achieve this control of the joint. In most cases, the damage to the underside of the cuff and the superior labrum is of such a minor degree as to require treatment. In other cases such as a true SLAP lesion acting as a biceps detachment or a bucket-handle direct treatment of the labrum as well as control of the mechanism of injury are necessary. Prevalence Because of the strict selection criteria in this study, patients who have gone on from the injury described to rotator cuff dysfunction and subacromial impingement would not be included in this series. They would be excluded by subacromial findings on arthroscopy. In addition, individuals who presented with shoulder pain but who responded to a conservative rehabilitation program are also not included in this series because there was no arthroscopic or imaging confirmation of their disease. Currently, in the patient whose problem is chronic repetitive injury, we are using a 2-month trial of strengthening of the cuff and scapular rotators before going on to arthroscopy. The prevalence of this mechanism of injury among patients with shoulder pain therefore is probably wider than is indicated by this small series but still represents a fraction of shoulder disease. In their series of young throwing athletes, Randelli et a1.7 found labral injury in conjunction with partial cuff damage in 12 of 92 examined by arthroscopy. This indicates that, as expected, this mechanism is more common in people who use the shoulder at the limit of glenohumeral motion.
SUMMARY A series of patients with shoulder problems secondary to an abduction or abduction external rotation mechanism has been presented along with a review of cases from the literature, showing: first, that there are five tissues at risk from this mechanism of injury: (1) the anterior inferior glenohumeral ligament and labrum, (2) the rotator cuff, (3) the posterior-superior glenoid labrum, (4) the greater tuberosity, and (5) the bone of the superior glenoid; second, that injury often occurs to more than one of these structures, therefore, injury to one of these structures indicates investigation of the other four; and third, that diagnosis may depend on a more detailed history. REFERENCES 1. Davidson PA, ElAttrache NS, Jobe CM, Jobe FW. Rotator cuff injury in the throwing athlete: A new site of impingement. A preliminary report. J Shoulder Elbow Surg (in press). 2. Jobe CM, Sidles .I. Evidence for a superior glenoid impingement upon the rotator cuff: Anatomic, kinesiologic, MRI and artbroscopic findings. Presented at the 5th international Conference on Surgery of the Shoulder, July 12-15, 1992, Paris, France, (abstr 079). 3. Walch G, Boileau P, Noel E, Done11 ST. Impingement of the deep surface of the supraspinatus tendon on the posterior superior glenoid rim: An arthroscopic study. J Shoulder Elbow Surg 1992; 1:238-245. 4. Codman EA. The shoulder. Reprinted by Krieger, Malabar, FL, (original copyright 1934) 1984272. 5. Harryman DT, Sidles JA, Clark JM, McQuade KO, Gibb TD, Matsen FA III. Translation of the humeral head with passive glenohumeral motion. JBone Joint Sure Am 1990:72: 1334-1343. 6. fannotti JP, Wang ED. Avulsion of the supraglenoid tubercle: A variation of the SLAP lesion. J Shoulder Elbow Surg 1992; 1:2630. I. Randelli M, Minola R, Gambrioli PL. The painful shoulder in young patients. The role of glenoid labrum and biceps lesions. Video presentation (V6) at the 4th International Congress on Surgery of the Shoulder, July 12-15, 1992, Paris, France. 8. Snyder SJ, Karzel RP, Del Pizzo, Ferkel RD, Friedman MJ. SLAP lesions of the shoulder. Arthroscopy 1990; 6:274-279.
Summary: Posterior superior glenoid impingement is a recently recognized mechanism of injury producing rotator cuff injury in athletes. Usually the mechanism is repetitive overhand activity such as throwing. A survey of the author’s practice was undertaken to show a wider spectrum of this mechanism both in the activity that caused it and the number of structures at risk of injury from this mechanism. The survey revealed 11 patients who had a clear recollection of their mechanism of injury and an objective documentation of the injury by arthroscopy or imaging studies. The majority of shoulders had damage to more than one of the five structures at risk from this mechanism of injury. Six caseswere not sports related. Glenoid impingement may injure one or more of the following: (1) superior labrum, (2) rotator cuff tendon, (3) greater tuberosity, (4) inferior glenohumeral ligament or labrum, and (5) superior glenoid bone. Injury to more than one structure may be the rule and injury to one structure may indicate investigation of the other four. Key Words: Rotator cuff injury-Labrum injury-Glenoid-Impingement syndrome-Shoulder instability-Mechanism of injury.
T
he source of rotator cuff damage and symptoms continues to be an area of controversy and a fertile area for discussion. It has been shown previously that within the glenohumeral joint, it is possible for the rotator cuff and adjacent greater tuberosity to make contact with the posterior superior glenoid and labrum.‘” Indeed, Walch et aL3 have presented a series of athletic patients showing that this contact can lead to pathology within the glenohumeral joint. To date, descriptions of posterior superior glenoid impingement identify athletic individuals where a repetitive throwing-like motion, causes shoulder pain, and physical findings suggesting impingement syndrome.‘,3 The relocation test can produce a physical finding that is helpful in distinguishing this entity from subacromial impingement. Pain rather than apprehension produced in 90” of abduction, hyperextension, and From the Department of versity School of Medicine, Address correspondence Jobe, M.D., Department of versity School of Medicine, Linda, CA 92350, U.S.A. 0 1995 by the Arthroscopy
Orthopaedic Surgery, Loma Linda UniLoma Linda, Calllfornia, U.S.A. and reprint requests to Christopher M. Orthopaedic Surgery, Loma Linda Uni11234 Anderson St, Rm. A519, Loma Association
of North
America
0749-8063/95/1105-1208$3.00/O
530
Arthroscopy:
The Journal
of Arthroscopic
external rotation is relieved by posteriorly directed pressure on the proximal humerus.’ The current interpretation of the relocation test is that the eliciting phase of the test creates impingement between the greater tuberosity and rotator cuff, and the posterior superior glenoid and labrum and creates the pain. Translating the humeral head posteriorly alleviates this pressure. Posterior superior glenoid impingement is felt to be the most frequent cause of rotator cuff disease seen in athletes often in association with anterior instability.’ A curious facet of the relocation test and the impingement seen on arthroscopy is that it has been reported only in athletic individuals with minor degrees of instability or no instability. A patient with a large subluxation or true dislocation would seem to be protected from making this kind of contact.“3 Increased attention to this mechanism of injury has brought out a larger spectrum of conditions arising by the same mechanism of injury. The conditions under which these injuries occur are not necessarily athletic, nor are they typical of the throwing motion. In some cases, the diagnosis has depended on extra effort in obtaining the history of the exact mechanism of injury. It is the purpose of this article to present a series of patients who demonstrate the larger spectrum of injury
and Related Surgery,
Vol 11, No 5 (October),
1995: pp 530-536
SUPERIOR
GLENOID
IMPINGEMENT:
TABLE 1. Posterior Superior Glenoid Pt. No.
9
Sex
F
Age
Occupation work
Work Related
Yes
Mechanism Injury
Structures
Road
43
Clerical
No
20
Student
No
50
Obstetrician
No
34
Dermatologist
No
55
Laborer
Yes
44
Stenographer
No
30
Homemaker
No
26
Laborer
Yes
22
PT student
No
Acute
43
Forklift
Yes
Chronic; abd ext rot position most of work day
Part cuff tear Chondromalacia postsup head Sup labral laxity Post sup cuff part tear jt side Labral changes
Chronic; sleeps on fully elevated arm Acute; dove from a height into water. Arms directly overhead. Acute; abd. ~90” ext rotation
Sup lab detached biceps (SLAP)
NOTE. Except for where a SLAP lesion is noted and adjacent synovium, and adventitial scar.
abd-ext
rot
Diagnosed by Dx. Made
Treatment Ant
capsulolabral reconst.
Outcome
Arthroscopy
Improved; return
didn’t to work
Rehab cuff serratus
&
Arthroscopy
Improved (nearly complete relief)
Joint side cuff damage Sup lab damage
Rehab cuff serratus
&
Arthroscopy
Complete
Fx tuberosity
Rest & rehab
Radiograph
Incomplete
Fx tuberosity
Rest
Complete
Inner cuff tear Deformed sup labrum (bursa entirely normal)
Arthroscopic debridem of tear for visualization then rehab Arthroscopic reattachment
MRI (not seen on radiograph) Arthroscopy
Compl Bankart
WI
cuff tear lesion
Part cuff tear Labral deform Chondromalacia adjacent to cuff
Bucket-handle Bankart lesion Part cuff tear
Labral Inside
AND METHODS
Eleven patients from the author’s practice fulfilled the following criteria: first, the patients had a clear
SLAP
deform cuff tear
(pt. 7 & 10) the labral
resulting from this mechanism. The larger spectrum refers not only to the larger number of activities that lead to injury but to the number of tissues at risk.
MATERIALS
Injured
Acute; moving wet sand bags; abduction ~90 ext rot Chronic; throwing (as a youth & as little league coach) Acute; fall from bicycle w/arm elev Acute; slipped on skateboard, violent active elevation Acute; slipped skiing violet active elev Acute; shoveling inj abd ext rot
531
Expanded Spectrum
of
36
driver
Impingement:
SPECTRUM
changes
consist
& rehab
Arthroscopy
relief
relief
relief
Relief of cuff pain; did not return to work secondary to other injuries Compl relief until reinj by falling object Restoration of active ROM; still has apprehens sign
Open cuff repair
MRI
Arthroscopic acromioplasty w/poor result then, revision of rehab program Arthroscopic exe of upper lab fragment Open ant capsulolabral recon. Rehab &job mod
Arthroscopy
Nearly complete relief; has returned to work
Arthroscopy
Complete
Arthroscopy
Relief achieved by change in job
of a change
in shape,
injected
appearance
relief
of labrum
recollection of their mechanism of injury: full elevation or abduction external rotation (Table 1). Patients with pathology but no clear recollection of their mechanism of injury were excluded. Second, on arthroscopic or radiographic examination, there was injury to one or more of the following five tissues: the inner surface of the rotator cuff, the posterior-superior labrum, the inferior glenohumeral ligament labrum complex, the
532
c. M. JOBE
FIG 1. Photograph and sketch of a cadaver specimen with the arm in full elevation shows the five structures prone to injury by this mechanism: (1) greater tuberosity, (2) rotator cuff tendon, (3) superior labrum, (4) inferior glenohumeral ligament and labrum loaded in tension, and (5) superior glenoid bone. The inferior glenohumeral ligament is loaded in tension, the other four in compression.
greater tuberosity, or the bone of the superior glenoid (Fig 1). Patients with other pathology such as calcific tendinitis and subacromial pathology were excluded. Also excluded by these criteria would be patients who responded to a rehabilitation program early on and would therefore not undergo arthroscopy. As this study clarified the diagnostic spectrum, the rehabilitation protocol before surgery has been altered. Under the current approach, there is a more extensive trial of rehabilitation that would have probably eliminated the need for arthroscopy in patients 2, 3, and 5. RESULTS History Recognition of the mechanism of injury usually depended on the patients recall but in at least one case (patient 11) required reeducation of the physician as to the exact nature of the patient’s work. Patient 11, a forklift driver, went unrecognized at
arthroscopy partly because he did not fit the prevailing pattern of the supraglenoid impingement patient at the time (i.e., he was not a thrower), and because his surgeon did not understand how a forklift is driven. The surgeon thought that forklifts were driven in the same manner as automobiles. An elevation or abduction external rotation injury seemed highly unlikely at the time of surgery as a cause of rotator cuff damage. The patient, after specific questioning about the nature of his activities, was better able to explain his mechanism of injury. Because loads are stacked so high, forklift drivers cannot see over them. To drive safely, the patient and other forklift drivers spend 80% of their time driving backwards looking over the opposite shoulder (Fig 2). This has been confirmed by the warehouse manager at Loma Linda University. Physical Findings Seven of the patients had positive relocation test results. The two patients (patients 4 and 5) with greater
SUPERIOR
GLENOID
IMPINGEMENT:
SPECTRUM
533
shows a wider spectrum of pathology resulting from this mechanism than has been discussed in the past.
Mechanism
FIG 2. The position in which patient 11 spent the majority of his working day. To drive safely, he and other forklift drivers must drive in reverse putting at least one shoulder into the abducted externally rotated position. Fatigue of the upward rotators of the scapula would cause the driver to rest the glenohumeral joint in the impinged position. Some drivers place the opposite arm, the right arm in this illustration, into abduction-external rotation. They do this so they can use the right hand on the frame to assist with rotating the torso. This second position would place both shoulders at risk.
tuberosity fractures could not be tested secondary to pain. Patients 8 and 10 with Bankart lesions experienced apprehension before achieving the position of the relocation test.
Injury
to Specific Structures
Damage to one or more of the structures at risk was found in all patients. Of the eight patients who underwent arthroscopy, seven had damage to more than one structure (3 patients with 3 structures injured, 4 patients with 2). As the two tuberosity fractures were diagnosed by other means, soft tissue injury would not have been revealed. No patient was found with fracture of the superior glenoid.
DISCUSSION This mechanism of injury as a source of rotator cuff damage has come to light only recently, but had been mentioned previously by Codman as a cause of greater tuberosity fracture (Fig 3). This series of patients
of Injury
and Tissues at Risk
The glenohumeral joint has been found to function basically as a ball and socket joint, with a relatively steady center of rotation with small translations at extremes of motion.5 Definition of the terms describing motion is in order. As with any ball and socket joint, the spinning type of motion, i.e., motion where the center of the ball does not move relative to the socket, can be subdivided with respect to an axis of the ball into angulation and rotation (Fig 4). The two most important axes of the glenohumeral joint are the axis of the shaft, which has a boney representation and is, therefore, most useful for clinical and kinesiologic purposes, and the axis of the articular cartilage, which is the true “axis of the joint” but unfortunately has no boney representation. Angulation is motion of an axis relative to the glenoid and rotation is motion about that axis. In angulation, there tends to be at the extreme a slight translation in the same direction as the capsule opposite the angulation tightening. Tissues at the edges of the articular cartilage in the direction of angulation will approach each other and make contact. The mechanism of injury we are discussing here represents an angulation either directly superiorly, elevation as in Neer’s test for impingement, or posterior superiorly, abduction-external rotation as in throwing. This extreme angulation places five different structures at risk: (1) the inferior glenohumeral ligament and labrum, (2) the rotator cuff, (3) the posterior superior labrum, (4) the greater tuberosity, and (5) the bone of the superior glenoid. The angulation of the joint is limited by the inferior glenohumeral ligament, and increased angulation beyond the normal range will result in stretch of the ligament and/or its labral insertion. Compression stresses occur in the superior glenoid labrum, the inner fibers of the rotator cuff, the bone of the greater tuberosity, and the bone beneath the labrums The inferior glenohumeral ligament is, in these two positions, draped over the prominence of the articular surface of the humeral head (Fig 1). The fibers at the apex of this bulge will bear the highest stress, with a decrease in stress as one moves away from the apex of the bulge. Stretch of these fibers at the apex of the bulge will allow an increase in angulation. Continued angulation loads will result in stretch of adjacent fibers, and can eventually lead to an increase in translation or minor grades of anterior subluxation as noted earlier.’
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d FIG 3. Codman’s concept of how the greater tuberosity fracture occurs by impingement against the glenoid. Note the resemblance to Fig 1. (The letters “b” and “d” are Codman’s designation.) (Reprinted with permission?)
The rotator cuff in this position finds its innermost or articular side fibers compressed against the glenoid labrum. The normal course of these cuff fibers contouring the humeral head is reversed so that the cuff approaches the greater tuberosity at an angle 90” different from that at rest. In addition, a reversed curve occurs in the fibers of the cuff with the inner fibers
now on the convexity while they are on the concavity at rest. The compression of the inner fibers as well as the shear stresses arising within the tendon secondary to this reversed angle of approach may result in a partial cuff tear. There is a gradation between minor and major changes. A minor change in the rotator cuff such as a small “rim rent” or an incomplete tear that leaves the majority of the tendon intact may mislead the surgeon into believing there is a subacromial problem. In fact, it is glenohumeral angulation that needs to be controlled, either by physical rehabilitation or by anterior capsular repair.’ It is conceivable that additional tearing into the substance of the tendon may affect the ability of the rotator cuff to function. In these cases, there could develop rotator cuff dysfunction as well as hyperangulation: in other words, subacromial impingement on top of glenoid impingement. The labrum in this type of injury is deformed by its contact with the inner rotator cuff and greater tuberosity. In this tissue, too, there are gradations of injury. The injury may, in minor cases, present as deformity of the labrum or build-up of adventitial scar tissue, in which case a simple debridement and a correction of the glenohumeral mechanics should alleviate the problem. The higher grade injury is a SLAP lesion, which may require surgical excision of unstable labrum or a surgical reattachment of the labrum and contiguous biceps origin.@ The bone of the humeral head, particularly the greater tuberosity, is brought against a sharp angle of the glenoid and labrum by this mechanism of injury.4 It is worth mentioning that in the author’s practice, these are the only two tuberosity fractures that occurred by this mechanism. Minor grades of damage may consist of trabecular fractures that are seen only on magnetic resonance imaging or arthroscopy. The next higher grade of injury would be a nondisplaced greater tuberosity fracture, which would require appropriate immobilization and rehabilitation. The highest grade of tuberosity injury would be a displaced tuberosity fracture requiring surgical correction. The fifth tissue at risk is the bone of the superior glenoid. No patients with this injury were found in this series. However, there are two patients with superior glenoid fractures reported by Iannotti and Wang.6 The injury in these two patients occurred by a chronic throwing type mechanism in two recreational athletes. Fatigue fractures of the superior glenoid occurred with superior labmm and biceps origin injuries in both patients. Both patients would have met the inclusion criteria for this series. Walch et aL3 also report stress changes in the sublabral bone visible on computed tomography.
SUPERIOR
GLENOID
IMPINGEMENT:
SPECTRUM
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FIG 4. Angulation and rotation with respect to the two most important axes of the glenohumeral joint: (A) the axis of the humeral articular cartilage “the axis of the joint” and (B) the axis of the shaft “the clinical axis.” Angulation of an axis is change of its orientation to the glenoid. Rotation is movement about the axis. In this drawing the “joint axis” is perpendicular to the glenoid while the shaft is in 45” of abduction.
Combination
Injuries
The question rises that if these five tissues are at risk from the same mechanism of injury, might combinations of injuries not occur. This series of patients points out that combination injuries may be the rule rather than the exception. Eight of the 11 patients had damage to more than one structure documented. Many patients with a partial rotator cuff tear have an anterior instability that requires surgical approach to the instability even though the rotator cuff tear is minor.’ The classic combination of dislocation with rotator cuff tear seen in the older patients may also occur in the younger patients (patient S).4 It is to be pointed out that one of the patients with a tuberosity fracture shown by radiography has continued shoulder pain even after healing of the fracture, leading one to believe that if arthroscopy had been performed, injury to rotator cuff, labrum, or anterior capsule might have been seen. One should not be surprised to find a SLAP lesion concomitantly with a rotator cuff tear or humeral head fracture. In fact, Randelli et a1.7 have reported on a group of 12 young athletes with SLAP lesions and a high frequency of partial rotator cuff tear, humeral damage, or subluxation. We have, in this small series, only one subject (patient 10) who had a SLAP lesion in combination with a Bankart lesion anteriorly. This SLAP lesion was so significant that it altered the pa-
tient’s symptoms, confusing the clinical picture. By the stated mechanism of injury and apprehension test, the patient should have had an anterior instability. But by her history of recurrent instability episodes and the maneuvers by which she reduced her shoulder, she ought to have had a posterior instability. (This patient is a physical therapy student and was able to give very reliable information on reduction techniques). It was only by arthroscopy that we were able to discover that she had two lesions, a traumatic anterior instability (i.e., Bankart lesion) and a significant bucket-handle type SLAP lesion that was mimicking a posterior instability. Given the appropriate injury history, the existence of one of these injuries should trigger a more careful examination of the other four structures.
Implications
for Treatment
Treatment of these individuals is often twofold. First it is aimed at the mechanism of injury by eliminating too much elevation or abduction external rotation by exercise or surgery, and second, many times the treatment must also be aimed at the injured structure. All patients except for the two physicians with tuberosity fractures underwent strengthening of the rotator cuff to control the glenohumeral joint and strengthening of the scapular rotators to decrease the glenohumeral angulation necessary to place the arm in elevation or
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abduction external rotation. Patients who fail with this treatment and those with dislocation require a repair of the anterior capsule and labrum to achieve this control of the joint. In most cases, the damage to the underside of the cuff and the superior labrum is of such a minor degree as to require treatment. In other cases such as a true SLAP lesion acting as a biceps detachment or a bucket-handle direct treatment of the labrum as well as control of the mechanism of injury are necessary. Prevalence Because of the strict selection criteria in this study, patients who have gone on from the injury described to rotator cuff dysfunction and subacromial impingement would not be included in this series. They would be excluded by subacromial findings on arthroscopy. In addition, individuals who presented with shoulder pain but who responded to a conservative rehabilitation program are also not included in this series because there was no arthroscopic or imaging confirmation of their disease. Currently, in the patient whose problem is chronic repetitive injury, we are using a 2-month trial of strengthening of the cuff and scapular rotators before going on to arthroscopy. The prevalence of this mechanism of injury among patients with shoulder pain therefore is probably wider than is indicated by this small series but still represents a fraction of shoulder disease. In their series of young throwing athletes, Randelli et a1.7 found labral injury in conjunction with partial cuff damage in 12 of 92 examined by arthroscopy. This indicates that, as expected, this mechanism is more common in people who use the shoulder at the limit of glenohumeral motion.
SUMMARY A series of patients with shoulder problems secondary to an abduction or abduction external rotation mechanism has been presented along with a review of cases from the literature, showing: first, that there are five tissues at risk from this mechanism of injury: (1) the anterior inferior glenohumeral ligament and labrum, (2) the rotator cuff, (3) the posterior-superior glenoid labrum, (4) the greater tuberosity, and (5) the bone of the superior glenoid; second, that injury often occurs to more than one of these structures, therefore, injury to one of these structures indicates investigation of the other four; and third, that diagnosis may depend on a more detailed history. REFERENCES 1. Davidson PA, ElAttrache NS, Jobe CM, Jobe FW. Rotator cuff injury in the throwing athlete: A new site of impingement. A preliminary report. J Shoulder Elbow Surg (in press). 2. Jobe CM, Sidles .I. Evidence for a superior glenoid impingement upon the rotator cuff: Anatomic, kinesiologic, MRI and artbroscopic findings. Presented at the 5th international Conference on Surgery of the Shoulder, July 12-15, 1992, Paris, France, (abstr 079). 3. Walch G, Boileau P, Noel E, Done11 ST. Impingement of the deep surface of the supraspinatus tendon on the posterior superior glenoid rim: An arthroscopic study. J Shoulder Elbow Surg 1992; 1:238-245. 4. Codman EA. The shoulder. Reprinted by Krieger, Malabar, FL, (original copyright 1934) 1984272. 5. Harryman DT, Sidles JA, Clark JM, McQuade KO, Gibb TD, Matsen FA III. Translation of the humeral head with passive glenohumeral motion. JBone Joint Sure Am 1990:72: 1334-1343. 6. fannotti JP, Wang ED. Avulsion of the supraglenoid tubercle: A variation of the SLAP lesion. J Shoulder Elbow Surg 1992; 1:2630. I. Randelli M, Minola R, Gambrioli PL. The painful shoulder in young patients. The role of glenoid labrum and biceps lesions. Video presentation (V6) at the 4th International Congress on Surgery of the Shoulder, July 12-15, 1992, Paris, France. 8. Snyder SJ, Karzel RP, Del Pizzo, Ferkel RD, Friedman MJ. SLAP lesions of the shoulder. Arthroscopy 1990; 6:274-279.