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SHOULDER IMPINGEMENT
CONSERVATIVE MANAGEMENT OF SHOULDER INJURIES
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SHOULDER IMPINGEMENT David S. Morrison, MD, Brad S. Greenbaum, MD, and Andy Einhorn, PT, CSMT
Subacromial impingement with rotator cuff tendinitis is probably the commonest shoulder condition seen by the orthopedic surgeon. If left untreated or misdiagnosed, partial-thickness and full-thickness rotator cuff tears may result. The impingement process can be caused by several mechanisms. The cause can range from mechanical factors to glenohumeral instability. Understanding the pathophysiology and the treatment of this disorder is the keystone to understanding all other aspects of shoulder rehabilitation. Impingement rehabilitation focuses on strengthening the humeral head depressors, while ignoring the deltoid and supraspinatus muscles. Later treatment includes specific retraining of scapular balancing muscles. The final phase of treatment includes strengthening of the prime humeral movers in positions that avoid further stress to the previously injured rotator cuff tendons and, last of all, specifically strengthening the supraspinatus muscle.
ANATOMY There are several theories as to the exact cause of subacromial impingement syndrome and rotator cuff tendinitis. These two terms are not interchangeable. Impingement syndrome refers to a specific pathologic condition in which there is irritation of the supraspinatus tendon
secondary to abrasion against the undersurface of the anterior one third of the acromion. Rotator cuff tendinitis, which encompasses impingement, also may be a result of acute rotator cuff overload, intrinsic rotator cuff degeneration, or chronic overuse. The term rotutor cuff syndrome is used to describe the process whereby tendinitis and impingement are ongoing simultaneously. In the authors’ practice, approximately 75% of all patients with rotator cuff tendinitis are believed to have an underlying impingement of the anterior acromion on the supraspinatus and occasionally the infraspinatus tendon. Approximately 10% of the patients have a chronic overuse cuff pathology, and 5% have an acute rotator cuff strain. The remaining 10%have an intrinsic tendon disruption as a result of agerelated degeneration. There are four major causes of rotator cuff tendinitis: external anatomic impingement, internal anatomic impingement, functionaloverload, and intrinsic tendinopathy. External anatomic impingement may be further broken down into problems related to acromial morphology; glenohumeral instability; or secondary to anatomic abnormalities, such as acrornioclavicular (AC)joint separations, nonunited anterior acromial epiphysis, acromial fracture nonunions or malunions, and displaced greater tuberosity fractures. Internal anatomic impingement refers to the presence of superior
From the Southern California Center for Sports Medicine, Long Beach (DSM, BSG); and Los Alamitos Orthopaedic and Sports Physical Therapy, Los Alamitos (AE), California ORTHOPEDIC CLINICS OF NORTH AMERICA VOLUME 31 * NUMBER 2 * APRIL 2000
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labral anterior-posterior (SLAP) lesions or deep surface rotator cuff tears, such as those seen in the posterior cuff of overhead athletes. Functional overload can be as simple as a strain from overuse or a partial-thickness tear secondary to overload at the tendon-bone interface or musculotendinous junction. The worst case of functional overload results in a complete cuff tear. Intrinsic tendinopathy is usually a degenerative process occurring over time and seen in an elderly population. Whether the primary cause of rotator cuff tendinitis is true external impingement or one of the other causes mentioned, most patients develop a secondary anatomic impingement as a result of altered biomechanics or disuse atrophy of the humeral head depressors. By the time patients present to a treating physician, this secondary anatomic impingement has already developed, and the rehabilitation protocol should be geared toward treating the underlying cause and treating the secondary anatomic impingement. As previously stated, impingement refers to irritation of the rotator cuff on the undersurface of the anterior-lateral acromion. During elevation of the humerus, a force couple is developed between the rotator cuff muscles and the deltoid muscle. The deltoid muscle originates from the acromion and inserts down the arm on the deltoid tuberosity of the humerus. As the deltoid muscle contracts, it pulls the humeral head up and at the same time begins the elevation of the humerus. In the absence of humeral head depressors, the humerus abuts against the underside of the acromion and makes glenohumeral elevation beyond 90" extremely difficult. With the addition of the rotator cuff, the humeral head is depressed and centralized in the glenoid fossa and allowed to clear the undersurface of the acromion. Now the arm may be further elevated to 120". The remaining 60" of elevation is due to a synchronous and concurrent rotation of the scapula of 60". This rotation allows total forward elevation to 180". This is an extremely simplified overview of shoulder mechanics, but it incorporates all the major elements of function that must be understood to begin a discussion on rehabilitation. In the normal individual, the space between the greater tuberosity and the undersurface of the acromion is approximately 6 to 7 mm. The thickness of the rotator cuff tendon in this area is approximately 5 to 6 mm. There is little clearance between the rotator cuff and the nor-
mal acromion. In fact, during normal function, there is light contact between the cuff and the coracoacromial arch.' With adequate function of the rotator cuff, however, the humeral head does not ride up during arm elevation, contact is minimized, and impingement irritation does not occur. As an individual ages, it appears that the massive deltoid muscle retains its strength longer than the relatively diminutive rotator cuff muscles. According to one theory, this situation allows the deltoid to overpower the rotator cuff during elevation, causing the head to rise up and the anterior acromion to impinge on the rotator cuff tendons. The treatment of this condition is to increase the space between the anterior acromion and the rotator cuff tendons. There are three ways of approaching this problem. One of them is surgically. An anterior acromioplasty removes bone from the undersurface of the anterior-latera1 acromion and releases tension on the coracoacromial ligament. This procedure increases the clearance between the acromion and the rotator cuff and decreases contact pressure. Often, however, this operation is unnecessary. A second approach is with subacromial injections of cortisone. Although these injections do not cure underlying pathology, they decrease the swelling of the inflamed bursal and rotator cuff tissue and allow for more room in the subacromial space for the rotator cuff tendons to move. Finally, a similar increase in clearance can often be achieved with rotator cuff-strengthening exercises. A strong cuff can provide a few millimeters of humeral head depression. This depression effectively increases the subacromial space similar to an acromioplasty and allows an inflamed rotator cuff a chance to heal without further irritation. Proper physical therapy is the key to accomplishing the goal of decompressing the cuff. The oblique muscles of the rotator cuff-the inferior portions of the infraspinatus and subscapularis and the entire teres minor-attach to the humerus at approximately 45" to the shaft. During initiation of elevation, these muscles act not only as humeral head stabilizers and rotators, but also as significant humeral head depressors. If the inferior portion of the rotator cuff can be strengthened, while ignoring and possibly weakening the deltoid muscle, a normal balance between the deltoid and the rotator cuff muscles can be reestablished. Elevation of the humerus without superior migration of the humeral head can then
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occur without impingement. This theory is the basis for all shoulder rehabilitation for rotator cuff disease. Although this is a rather simplistic look at a complex problem, it is quite useful to the basic understanding s f subacromial impingement. There are additional factors to consider, such as the scapular stabilizers and the accessory muscles of humeral movement. Understanding the basic principles of balance between humeral head elevation and depression is the basis for understanding the theory behind rotator cuff rehabilitation. In one large study, a therapy program based on this theory had a 70% success rate in treating patients with chronic subacromial im~ingernent.~
THERAPEUTIC CONSIDERATIONS Proper individualized shoulder rehabilitation enhances the nonoperative and operative treatment of shoulder impingement. Rehabilitation should begin as early as possible after injury or surgery. Initial therapy should assist rather than retard soft tissue healing. This therapy speeds the return to activity and shortens the period of disability. Rotator cuff rehabilitation should be conducted in a manner that promotes normal scapulohumeral rhythm. This rehabilitation should include synchronicity of the glenohumeraland the scapulothoracic force couples. Often, rehabilitation fails to address the importance of the scapulothoracic force couple. Such is the case in impingement secondary to instability, in which the scapulothoracic joint needs to work at a higher functional level to compensate for the dysfunctional glenohumeral joint. Impingement rehabilitation should place its emphasis on strengthening three main areas: humeral head depressors (subscapularis, infraspinatus, and teres minor), scapular balancing muscles (upper and lower trapezius, serratus anterior, and rhomboids), and prime humeral positioners (deltoid, pectoralis major, and latissimus dorsi).
Scapular Function The significance of the scapular rotators is frequently overlooked. The serratus anterior and trapezius muscles are crucial to the movement of the scapula around the thorax, especially in conjunction with elevation. These
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muscles contribute to optimal positioning of the scapula during overhead activities and serve an equally important function as stabilizing synergists for the deltoid acting at the glenohumeraljoint. Norkin and Levangie6and Scovazzo et ale have written about the significance of the serratus anterior muscle in relation to swimmers with painful shoulders. As the serratus anterior muscle fatigues, the scapula is unable to keep up with the humerus. The humeral head continues to translate anteriorly, leading to further instability and rotator cuff impingement. If this problem is overlooked, overstretching of the capsule occurs and sets up the vicious cycle of progressive glenohumeral laxity and impingement. The glenoid fossa must move in synergy with the humeral head and shaft so that the instant center of humeral rotation is as close as possible to the same position throughout the extremes of overhead movement. This concomitant movement of the glenoid and humeral head helps to improve glenohumeral congruency by maintaining proper length-tension relationships of the muscles that anchor the humerus to the scapula. Scapula positioning contributes to the finetuning of the upper extremity kinetic chain in several ways. It provides an important link in the control of the tensile stresses placed on the anterior capsuloligamentous structures, particularly as they relate to the throwing motion. Energy that has been stored up in the cocking phase of throwing (maximalabduction and external rotation) needs to be dissipated. This dissipation of energy is accomplished by the mechanism of humeral deceleration and is fine-tuned through a system of scapular braking. As the humerus moves anteriorly during acceleration and follow-through phases of throwing, eccentric control of the rhomboids helps to dissipate the forces that are being generated on the posterior rotator cuff muscles. This dissipation of forces decreases the chances of tensile overload injury to the posterior capsule and rotator cuff muscles, which act eccentrically during the follow-through phase of throwing. During this phase of throwing, the humems is adducted and internally rotated, and the humeral head migrates into a posterior position. Failure to control these stresses can result in posterior subluxation. These stresses are dissipated by the bony stability of the protracted scapula and by the posterior shoulder capsule. Scapular protrac-
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tion is a function that is often overlooked in the evaluation of posterior shoulder instability.
Evaluating the Scapula
Scapular stability and control is essential to proper shoulder rehabilitation. The anchoring position of the scapula can be estimated clinically by using the lateral side measurement test described by Kibler.4 This test measures the posterior shoulder muscles’ ability to accomplish scapular stabilization and positioning. It also serves to provide a static measurement of scapular stability in three positions. The lateral scapular slide test is illustrated in Fig. 1. These positions measure the ability of the scapular stabilizersto control the medial border of the scapula. Another method used to evaluate the efficiency of the scapular platform is manual muscle testing. Although this method is considered subjective,it often proves beneficial in the evaluation and treatment of complicated problems of scapular positioning and control.
THERAPY AND REHABILITATION
Various rehabilitationapproaches have been suggested for conservative management of impingement syndrome and rotator cuff tendinitis. Past attempts at rehabilitation have placed considerable emphasis on isolation of the supraspinatus muscle. Review of biomechanical function of this highly studied muscle reveals that it primarily acts in concert with the deltoid as a humeral elevator and secondarily assists with compression and stabilization of the humeral head in the glenoid fossa. With this knowledge in mind, one should recognize its limited biomechanical function as a humeral head depressor. The rehabilitation protocol presented here is based on strengthening the true humeral head depressors, the oblique rotator cuff muscles. By strengthening these internal and external rotators at the side, the pull of these muscles works to depress the humeral head, increase the acromial humeral interval, and decrease impingement. Strengthening the deltoid muscle is counterproductive and specifically contraindicated because its action promotes elevation of the humeral head, a decrease in the acromial humeral interval, and increased subacromial contact pressure.
CLINICAL APPLICATION
Rehabilitation of impingement syndrome should be conducted in a systematic fashion. It can be divided into three areas of concentration: decreasing inflammation, soft tissue stretching, and strengthening. Following is a synopsis of the authors’ nonoperative management of rotator cuff syndrome. Decreasing Inflammation
Patients who suffer from rotator cuff syndrome need adequate rest from the activities that have inflamed the rotator cuff. Rest is often too short. The length of time may vary from a few days to a few weeks, depending on the underlying cause of impingement. Nonsteroidal anti-inflammatory medication and a limited number of subacromial steroid injections are useful to decrease inflammation but are not a cure for the actual problem. Physical therapy modalities, such as phonophoresis or iontophoresis, can be used for a determinate amount of time (i.e., six to seven treatments). Proper position of the shoulder enhances use of these modalities be exposing the actual site of cuff inflammation. In many cases, however, the actual area of irritation cannot be exposed because of bony anatomy. If the area of inflammation can be exposed, deep friction massage and ice application can also be beneficial. Soft Tissue Stretching
Inflammation usually can be controlled within I to 2 weeks. At this point, the rehabilitation program can address specific range-ofmotion limitations that need to be corrected. Prolonged shoulder pain causes the patient to restrict instinctively the range of use and often results in an initial adhesive capsulitis at the extremes of motion. This capsulitis must be corrected before strengthening can begin. The stretching exercises that the authors use are passive and active assisted. Most can be performed by the patient independently with few follow-up visits to the therapist. Occasionally, specific forms of joint mobilization are required when patients present with adhesive capsulitis secondary to impingement. In this case, the patient may have pain related to the impingement and the adhesive capsulitis. Initial treatment should be directed at the return
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Figure 1. Lateral scapular slide test. A, Position 1, with arms in a neutral position at the side. Dots illustrate the medial border of the scapula and the spinous process, respectively. The examiner measures the distance between the two dots bilaterally. B, Position 2, the patient places hands on the hips with the thumbs pointing posteriorly.This position requires trapezius muscle activity. Again the distance is measured and is greater than that seen in position 1. C,Position 3 is one of maximum challenge to the scapular stabilizers. The humerus is abducted 90 degrees and internally rotated. Scapular stabilization requires muscular activity of the upper-lower trapezius and serratus anterior muscles. Again, bilateral measurements are taken. In symptomatic individuals, differences of more than 1 to 2 cm in either position 2 or 3 have been shown statistically to have increased pain and decreased shoulder function on the affected side.
of motion and avoiding impingement positions. Capsular stretching is directed to the return of normal roll-gliding, which is required for humeral elevation. As range of motion improves and stiffness decreases, pain levels should decrease.
When a large subacromial spur is present, initial rehabilitation goals should emphasize capsular stretching to help improve internal and external rotation. Range of motion should include specific precautions against driving previously injured subacromial tissue into the
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region of a subacromial spur. This situation can occur if the therapist insists on forcing motion out of the plane of maximal elevation. The plane of maximal elevation is the scapular plane rather than the coronal plane (abduction) or sagittal plane (flexion). The capsule of the glenohumeral joint is most relaxed in the scapular plane, allowing the highest upward excursion with the greatest ease and freedom of movement. Movements in this plane occur more naturally and with less effort during normal activities of daily living. Passive humeral movement in the sagittal plane is avoided because this movement causes increased capsular tightening, which drives the humerus into the undersurface of the overhanging acromion. Humeral distraction should always accompany passive elevation in the plane of the scapula. This distraction helps avoid further pinching of the cuff beneath the acromion. As the capsular pattern (loss of external rotation more than elevation or internal rotation) decreases, treatment progresses to strengthening of the humeral head depressors. Strengthening the Humeral Head Depressors
As the rotator cuff-deltoid force couple relationship improves, the humeral head clears the undersurface of the anterior acromion, and active forward elevation should improve. This improvement can be achieved with a specific cuff-strengthening protocol. The authors begin with isometric exercises directed toward the oblique muscles of the rotator cuff with the arm at the side. With the arm in neutral rotation at the patient's side and the elbow bent 90°, isometric external rotation is performed against the resistance of the patient's opposite hand or an inanimate object, such as a wall. The resistance is held for 10 seconds each repetition. Three sets of 10 repetitions alternating right and left arms are performed. Once these exercises are tolerated, the patient can begin light isotonic exercises using an exercise band or surgical tubing. The tubing can be tied to a doorknob, and the arm is internally or externally rotated against the resistance of the tubing. Three sets of 10 repetitions alternating right and left arms should be performed. The patient should just barely be able to complete the third set of 10 repetitions. If the patient cannot complete all the sets, the resistance is too high; likewise, if completing the task is relatively easy, the resistance is too light. When performed properly, the program should take
only about 15 minutes twice each day. If the patient is able to perform these exercises without pain, dynamic rotator cuff strengthening can begin. With the arm at the patient's side, the same exercises are performed through an arc of -30" to +30" of rotation. Emphasis should be placed on the eccentricphase of contraction (3 seconds concentric, 7 seconds eccentric). Three sets of 10 repetitions are performed alternating right and left arms as well as internal and external rotation. During all these exercises, it is imperative that the deltoid remain in a relaxed position. Abduction of the arm is to be avoided. One helpful tool in achieving this is to place a magazine between the arm and chest wall and hold it there while performing the exercises. This position requires an adduction force and eliminates any deltoid contracture. Patients should be advised that cuff reconditioning takes at least 6 weeks. In the authors' experience, however, patients should begin to experience relief from symptoms by 4 to 6 weeks. If no improvement is noted within this time frame or if the exercises are irritating to the patient's shoulder this is a good indication that the patient is not likely to respond to the exercise protocol. A longer period of rest can be prescribed, or imaging scan should be obtained to look for a rotator cuff tear. In most patients who are not active athletes, symptoms can be controlled through the aforementioned protocol. About 17% of patients tend to have a recurrence of symptoms even though an initial satisfactory result was obtained. Most respond by simply resuming the exercise program. In high-caliber athletes, eccentric cuff strengthening is the final stage of cuff rehabilitation before scapular stabilization exercises. Eccentric cuff strengthening is particularly important in patients who participate in repetitive overhead activities that require humeral deceleration. Side-lying eccentric external rotation with a dumbbell can be added with emphasis on low weight and high repetitions.The patient is instructed to avoid overloading these muscles with heavy poundage because the external rotators are weak muscles even in nonpathologic shoulders. Five to 8 lb would be considered heavy levels of resistance. Internal rotators also receive eccentric attention but require heavier poundage during training. Athletes involved in activities that require overhead movements can be progressed to high-speed isokinetics, performed in the plane of the scapula. After 6 weeks of strengthening the internal and external rotators, the patient's
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shoulder pain should have significantly improved. At this point, the patient is advised to continue exercises at home until the pain completely resolves. A maintenance program is also discussed. Patients who continue to have pain and do not begin to improve after 6 weeks of exercise are advised to return for further evaluation. Patients presenting with weakness or decreased control of the scapular positioning muscles should receive appropriate strengthening exercises, in addition to strengthening the oblique rotator cuff muscles. Strengthening the Scapular Balancing Muscles
Re-educating and conditioning the scapular musculature can have a surprisingly large impact on the correction of various impingement problems. Often the normal motor organization and force couples must be restored. In doing so, the improved scapular position and motion decrease acromial impingement and increase rotator cuff efficiency. Rehabilitation should always start at the base of the kinetic chain. Strength and flexibility deficits in the lower back and thoracic level spine should be addressed and corrected first. Trunk flexion, extension, and rotation must all be strengthened. Postural abnormalities should be addressed and corrected with proper exercises as well. Specific scapular rehabilitation can be broken down into stability exercises, closedchain exercises, and open-chain exercises. Scapular stability exercises can be started early and involve isometric exercises. Scapular shrug exercises for elevation and scapular pinching exercises for retraction are examples of isometrics that can be done. Further aid with controlling of scapular position can be obtained by taping the scapula in a retracted or an elevated position or by using a figureeight collar similar to those used for clavicle fractures. Once isometric exercises have been tolerated, closed-chain exercises should be added. These exercises have the greatest influence on reorganizing and reestablishing normal motor firing patterns for the scapula. Because these exercises are done with the arm at 909 they reproduce the normal physiologic patterns of cocontractions of the scapular stabilizing muscles and the muscles of the rotator cuff. With the patient’s hand stabilized on a wall, specific scapular maneuvers of elevation, depression, retraction, and protraction can be performed. Further loads may be placed on the scapula by progressing to push-ups, quad-
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riped and biped exercises, and press-up exercises. Finally, open-chain exercises are begun. These are more strenuous exercises and include vigorous proprioceptive neuromuscular facilitation patterns, diagonals, external rotation and retraction activities, and plyometrics. In this phase, machines may be used to allow upright rows, pull-downs, and push-ups. Because the scapula is the base from which the rotator cuff originates, some believe that a complete scapular rehabilitation should proceed any rotator cuff-strengthening exercises. A re-educated scapula allows for more normal scapular positioning and more normal patterns of activation of the rotator cuff. Furthermore, with control of the scapula comes control of acromial elevation, which decreases the chances of further impingement. Strengthening of the Prime Humeral Positioners
Once the humeral head depressorsare strong and scapular balancing has been achieved, strengthening techniques are directed at the prime humeral positioners. These techniques are directed at the glenohumeral muscles and emphasize three-component motions. Shoulder flexion and extension, adduction and abduction, and internal and external rotation are all performed against resistance. Optimizing sequencing of muscle facilitation allows the muscles to contribute their components of action consistently.This form of manual patterning closely resembles movements used in sports and overhead work activities. Each diagonal pattern is made up of two antagonistic movements. Each pattern has a major component of flexion or extension. Movement patterns can be modified to begin with isometric contractionsperformed in a limited, protected, or pain-free range. Concentric and eccentric techniques can also be used. As the rehabilitation program progresses, full range of motion is performed using smooth, coordinated linear and diagonal patterns of movement. SPECIFIC TREATMENT BY CAUSE External Anatomic Impingement
There are several causes of external anatomic impingement, including instability, acromial morphology, and anatomic abnormalities. A concerted effort must be made to delineate the exact cause before beginning a
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rehabilitation program. If the primary problem is an anatomic abnormality, such as an acromioclavicular separation with a drooping scapula, a reconstruction of the ligaments, such as a Weaver-Dunn procedure or modification thereof, is in order. Fractures of the greater tuberosity or acromion need to be anatomically reduced to avoid impingement caused by the displaced fragment. A nonunited acromial epiphysis should be recognized as a possible causative agent in impingement. Treatments can vary depending on the size of the epiphysis, the patient’s age, and the patient’s activity level. Even after the treatment of these anatomic abnormalities, the rotator cuff injury often remains. At that point, the routine physical therapy protocol outlined in this article should be used. When instability is the underlying cause, laxity of the glenohumeral ligaments allows some superior migration of the humeral head with impingement of the greater tuberosity on a relatively normal acromial undersurface. Stabilization of the glenohumeral joint is the treatment of choice in these patients. This stabilization can be done surgically when necessary but often can be accomplished with a rotator cuff -strengthening program. The initial protocol is the same one used for primary impingement, but once initial relief of symptoms has been obtained, a general shoulderstrengthening and capsular stabilization program is undertaken to control future symptoms. Once a diagnosis of external anatomic impingement is made and anatomic abnormalities have been ruled out, a conservative rehabilitation program can be started. Internal Anatomic Impingement
Internal anatomic impingement is the theory put forth independently by two investigators, Jobe and Walch (personal communication, 1991).It states that deep surface rotator cuff tears and SLAP lesions may be the result of an internal impingement process. In a lax shoulder, an abduction and external rotation maneuver can cause the humerus to sublux anteriorly. This subluxation, in turn, can cause the greater tuberosity to impinge on the posterior-superior aspect of the glenoid. The deep surface of the rotator cuff can get pinched in between these two structures causing partialthickness tearing of the cuff. Likewise, the posterior-superior aspect of the labrum can get
sheared off its glenoid attachment in a similar manner. If the labrum is detached, further instability can result. A fall or a blow to the outstretched arm in a forced elevated position can cause a similar phenomenon. The increased laxity must be addressed in the rehabilitation program primarily and the rotator cuff secondarily. Once the proper therapy has been administered for the instability, the cuff symptoms usually resolve. Functional Overload
More than any other athletically active joint, the shoulder relies on its musculature for stabilization and protection. It is subject to overuse injuries. This situation is exceptionally common at the beginning of an athletic season or after a prolonged layoff. Even simple muscle fatigue can cause a burning-type pain down to the lateral deltoid or in the infraspinatus fossa. Although the arm may fatigue easily, the pain associated with this fatigue should usually clear quickly after icing down at the end of practice. Overuse syndromes are initially treated with modification of the athletic activity to decrease irritation as much as possible. These athletes are best treated with a progressively aggressive rotator cuff -strengthening program, anti-inflammatory medications, icing, and a general shoulder stabilization program to improve strength and functional stability. Often the athletes can make modifications in training to decrease the amount of time spent performing the offending activity. For example, a pitcher having shoulder pain could continue hitting, play some first base, and limit the amount of pitching done in a practice. At times, a single massive traumatic event, such as an off-balance throw or a fall, can cause a partial-thickness rotator cuff tear. These injuries occur at either the musculotendinous junction or at the tendon-bone interface.The conservativeprogram described generally works for tears at the musculotendinous junction; however, healing times can take 5 or 6 months. The results for tears at the tendonbone interface are much less predictable. Although these can heal by conservative means, surgery is often needed. Overall, these types of overload tears are rare and are being mentioned here only for completeness. Full-thickness overload cuff tears are also possible. These tears also occur from a single violent injury. In the authors’ experience, there is no con-
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servative management for full-thickness tears of this type. Surgery usually is indicated. Intrinsic Tendinopathy
Patients who are treated for suspected intrinsic degeneration of the cuff tendons are usually older. These patients tend to be less compliant with the authors' standard rotator cuff-strengthening protocol than patients with external impingement. Because of this tendency, the authors often modify the protocol to include more frequent follow-ups with the therapist, continued use of the anti-inflammatory medications on a long-term basis as opposed to the usual 3 to 6 weeks, and a modification of the offending activities during treatment. EXERCISE EQUIPMENT MODIFICATIONS
A systemic approach toward weight training is needed when establishingguidelines for the home program. Surgeons and therapists should become familiar with the various types of equipment available in local health clubs. This familiarity enables them to provide guidelines on equipment selection and exercise modification, in an effort to prevent further shoulder injury because of improper use. Various exercise machines are designed for increasing deltoid strength, but they place the rotator cuff tendons at risk. For example, ZateraZ raises or humeral abduction with internal rotation can cause further inflammation to the subacromial tissues. Machines designed for strengthening the pectoralis and anterior chest muscles can also irritate subacromial tissues when the patient starts the exercise in the extremes of flexion, abduction, and external rotation. Equipment modifications for this particular exercise include adjustment of the weight stack, raising the top plate, and replacing the stack pin. Additional exercises, such as upright rowing, behind-the-neck pull-downs, and military press, should be completely avoided. During the bench press, the patient is advised to keep the hands in sight during this exercise and lower the bar no further than the position at which the humerus is parallel to the floor. Patients are advised that exercises for strengthening the biceps and triceps can be used for general conditioning if the exercise is
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conducted with the humerus in the adducted position, with less than 90" of forward flexion. Rowing-type movements usually can be tolerated if the patient maintains this same position.
SUMMARY
Most patients who come to the authors' office having undergone previous shoulder rehabilitation have not experienced a therapeutic benefit. Most, however, have been treated with a suboptimal program. Hot packs, massage, and ultrasound, rarely produce results. The authors rarely see a patient who understands the cause of the shoulder pain and know the goals of the rehabilitation program. These are the most basic requirements for a successful program. The protocol outlined in this article is simple, is inexpensive, and takes up little time per day. As a result, the authors have been able to maintain a fairly high rate of nonoperative success with these patients. Using these methods, patients can expect about a 70% chance of resolution of symptoms.
References 1. Bigliani LU, Morrison Ds:Relationship between acromial morphology and rotator cuff tears. Orthop Trans 10:216, 1986 2. Einhom AR, Jackson DW. Rehabilitation of the shoulder. In Jackson DW (ed): Shoulder Surgery in the Athlete. Rockville, MD, Aspen Systems, 1985, pp 103-118 3. Jobe CM, Pink MM, Jobe FW, et al: Anterior shoulder instability, impingement and rotator cuff tear: Theories and concepts. In Jobe FW (ed): Operative Techniques in Upper Extremity Sports Injuries. St Louis, Mosby, 1996, pp 164-176 4. Kibler BW. The role of the scapula in athletic shoulder function. Am J Sports Med 2:325-337,1998 5. Morrison DS, Frogameni AD, Woodworth I? Conservative management for subacromial impingement syndrome. J Bone Joint Surg Am 79:732-737,1997 6. Norkin C, Levangie P: Joint structure and function: A comprehensive analysis. Philadelphia, FA Davis, 1983 7. Perry J: Biomechanicsof the shoulder. In Rowe CR (ed): The Shoulder. New York, Churchill Livingstone, 1988, pp 1-15 8. Scovazzo ML, et a 1 The painful shoulder during freestyle swimming: An electromyographic cinematographic analysis of hyelve muscles. Am J Sports Med 19577-587,1991
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SHOULDER IMPINGEMENT David S. Morrison, MD, Brad S. Greenbaum, MD, and Andy Einhorn, PT, CSMT
Subacromial impingement with rotator cuff tendinitis is probably the commonest shoulder condition seen by the orthopedic surgeon. If left untreated or misdiagnosed, partial-thickness and full-thickness rotator cuff tears may result. The impingement process can be caused by several mechanisms. The cause can range from mechanical factors to glenohumeral instability. Understanding the pathophysiology and the treatment of this disorder is the keystone to understanding all other aspects of shoulder rehabilitation. Impingement rehabilitation focuses on strengthening the humeral head depressors, while ignoring the deltoid and supraspinatus muscles. Later treatment includes specific retraining of scapular balancing muscles. The final phase of treatment includes strengthening of the prime humeral movers in positions that avoid further stress to the previously injured rotator cuff tendons and, last of all, specifically strengthening the supraspinatus muscle.
ANATOMY There are several theories as to the exact cause of subacromial impingement syndrome and rotator cuff tendinitis. These two terms are not interchangeable. Impingement syndrome refers to a specific pathologic condition in which there is irritation of the supraspinatus tendon
secondary to abrasion against the undersurface of the anterior one third of the acromion. Rotator cuff tendinitis, which encompasses impingement, also may be a result of acute rotator cuff overload, intrinsic rotator cuff degeneration, or chronic overuse. The term rotutor cuff syndrome is used to describe the process whereby tendinitis and impingement are ongoing simultaneously. In the authors’ practice, approximately 75% of all patients with rotator cuff tendinitis are believed to have an underlying impingement of the anterior acromion on the supraspinatus and occasionally the infraspinatus tendon. Approximately 10% of the patients have a chronic overuse cuff pathology, and 5% have an acute rotator cuff strain. The remaining 10%have an intrinsic tendon disruption as a result of agerelated degeneration. There are four major causes of rotator cuff tendinitis: external anatomic impingement, internal anatomic impingement, functionaloverload, and intrinsic tendinopathy. External anatomic impingement may be further broken down into problems related to acromial morphology; glenohumeral instability; or secondary to anatomic abnormalities, such as acrornioclavicular (AC)joint separations, nonunited anterior acromial epiphysis, acromial fracture nonunions or malunions, and displaced greater tuberosity fractures. Internal anatomic impingement refers to the presence of superior
From the Southern California Center for Sports Medicine, Long Beach (DSM, BSG); and Los Alamitos Orthopaedic and Sports Physical Therapy, Los Alamitos (AE), California ORTHOPEDIC CLINICS OF NORTH AMERICA VOLUME 31 * NUMBER 2 * APRIL 2000
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labral anterior-posterior (SLAP) lesions or deep surface rotator cuff tears, such as those seen in the posterior cuff of overhead athletes. Functional overload can be as simple as a strain from overuse or a partial-thickness tear secondary to overload at the tendon-bone interface or musculotendinous junction. The worst case of functional overload results in a complete cuff tear. Intrinsic tendinopathy is usually a degenerative process occurring over time and seen in an elderly population. Whether the primary cause of rotator cuff tendinitis is true external impingement or one of the other causes mentioned, most patients develop a secondary anatomic impingement as a result of altered biomechanics or disuse atrophy of the humeral head depressors. By the time patients present to a treating physician, this secondary anatomic impingement has already developed, and the rehabilitation protocol should be geared toward treating the underlying cause and treating the secondary anatomic impingement. As previously stated, impingement refers to irritation of the rotator cuff on the undersurface of the anterior-lateral acromion. During elevation of the humerus, a force couple is developed between the rotator cuff muscles and the deltoid muscle. The deltoid muscle originates from the acromion and inserts down the arm on the deltoid tuberosity of the humerus. As the deltoid muscle contracts, it pulls the humeral head up and at the same time begins the elevation of the humerus. In the absence of humeral head depressors, the humerus abuts against the underside of the acromion and makes glenohumeral elevation beyond 90" extremely difficult. With the addition of the rotator cuff, the humeral head is depressed and centralized in the glenoid fossa and allowed to clear the undersurface of the acromion. Now the arm may be further elevated to 120". The remaining 60" of elevation is due to a synchronous and concurrent rotation of the scapula of 60". This rotation allows total forward elevation to 180". This is an extremely simplified overview of shoulder mechanics, but it incorporates all the major elements of function that must be understood to begin a discussion on rehabilitation. In the normal individual, the space between the greater tuberosity and the undersurface of the acromion is approximately 6 to 7 mm. The thickness of the rotator cuff tendon in this area is approximately 5 to 6 mm. There is little clearance between the rotator cuff and the nor-
mal acromion. In fact, during normal function, there is light contact between the cuff and the coracoacromial arch.' With adequate function of the rotator cuff, however, the humeral head does not ride up during arm elevation, contact is minimized, and impingement irritation does not occur. As an individual ages, it appears that the massive deltoid muscle retains its strength longer than the relatively diminutive rotator cuff muscles. According to one theory, this situation allows the deltoid to overpower the rotator cuff during elevation, causing the head to rise up and the anterior acromion to impinge on the rotator cuff tendons. The treatment of this condition is to increase the space between the anterior acromion and the rotator cuff tendons. There are three ways of approaching this problem. One of them is surgically. An anterior acromioplasty removes bone from the undersurface of the anterior-latera1 acromion and releases tension on the coracoacromial ligament. This procedure increases the clearance between the acromion and the rotator cuff and decreases contact pressure. Often, however, this operation is unnecessary. A second approach is with subacromial injections of cortisone. Although these injections do not cure underlying pathology, they decrease the swelling of the inflamed bursal and rotator cuff tissue and allow for more room in the subacromial space for the rotator cuff tendons to move. Finally, a similar increase in clearance can often be achieved with rotator cuff-strengthening exercises. A strong cuff can provide a few millimeters of humeral head depression. This depression effectively increases the subacromial space similar to an acromioplasty and allows an inflamed rotator cuff a chance to heal without further irritation. Proper physical therapy is the key to accomplishing the goal of decompressing the cuff. The oblique muscles of the rotator cuff-the inferior portions of the infraspinatus and subscapularis and the entire teres minor-attach to the humerus at approximately 45" to the shaft. During initiation of elevation, these muscles act not only as humeral head stabilizers and rotators, but also as significant humeral head depressors. If the inferior portion of the rotator cuff can be strengthened, while ignoring and possibly weakening the deltoid muscle, a normal balance between the deltoid and the rotator cuff muscles can be reestablished. Elevation of the humerus without superior migration of the humeral head can then
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occur without impingement. This theory is the basis for all shoulder rehabilitation for rotator cuff disease. Although this is a rather simplistic look at a complex problem, it is quite useful to the basic understanding s f subacromial impingement. There are additional factors to consider, such as the scapular stabilizers and the accessory muscles of humeral movement. Understanding the basic principles of balance between humeral head elevation and depression is the basis for understanding the theory behind rotator cuff rehabilitation. In one large study, a therapy program based on this theory had a 70% success rate in treating patients with chronic subacromial im~ingernent.~
THERAPEUTIC CONSIDERATIONS Proper individualized shoulder rehabilitation enhances the nonoperative and operative treatment of shoulder impingement. Rehabilitation should begin as early as possible after injury or surgery. Initial therapy should assist rather than retard soft tissue healing. This therapy speeds the return to activity and shortens the period of disability. Rotator cuff rehabilitation should be conducted in a manner that promotes normal scapulohumeral rhythm. This rehabilitation should include synchronicity of the glenohumeraland the scapulothoracic force couples. Often, rehabilitation fails to address the importance of the scapulothoracic force couple. Such is the case in impingement secondary to instability, in which the scapulothoracic joint needs to work at a higher functional level to compensate for the dysfunctional glenohumeral joint. Impingement rehabilitation should place its emphasis on strengthening three main areas: humeral head depressors (subscapularis, infraspinatus, and teres minor), scapular balancing muscles (upper and lower trapezius, serratus anterior, and rhomboids), and prime humeral positioners (deltoid, pectoralis major, and latissimus dorsi).
Scapular Function The significance of the scapular rotators is frequently overlooked. The serratus anterior and trapezius muscles are crucial to the movement of the scapula around the thorax, especially in conjunction with elevation. These
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muscles contribute to optimal positioning of the scapula during overhead activities and serve an equally important function as stabilizing synergists for the deltoid acting at the glenohumeraljoint. Norkin and Levangie6and Scovazzo et ale have written about the significance of the serratus anterior muscle in relation to swimmers with painful shoulders. As the serratus anterior muscle fatigues, the scapula is unable to keep up with the humerus. The humeral head continues to translate anteriorly, leading to further instability and rotator cuff impingement. If this problem is overlooked, overstretching of the capsule occurs and sets up the vicious cycle of progressive glenohumeral laxity and impingement. The glenoid fossa must move in synergy with the humeral head and shaft so that the instant center of humeral rotation is as close as possible to the same position throughout the extremes of overhead movement. This concomitant movement of the glenoid and humeral head helps to improve glenohumeral congruency by maintaining proper length-tension relationships of the muscles that anchor the humerus to the scapula. Scapula positioning contributes to the finetuning of the upper extremity kinetic chain in several ways. It provides an important link in the control of the tensile stresses placed on the anterior capsuloligamentous structures, particularly as they relate to the throwing motion. Energy that has been stored up in the cocking phase of throwing (maximalabduction and external rotation) needs to be dissipated. This dissipation of energy is accomplished by the mechanism of humeral deceleration and is fine-tuned through a system of scapular braking. As the humerus moves anteriorly during acceleration and follow-through phases of throwing, eccentric control of the rhomboids helps to dissipate the forces that are being generated on the posterior rotator cuff muscles. This dissipation of forces decreases the chances of tensile overload injury to the posterior capsule and rotator cuff muscles, which act eccentrically during the follow-through phase of throwing. During this phase of throwing, the humems is adducted and internally rotated, and the humeral head migrates into a posterior position. Failure to control these stresses can result in posterior subluxation. These stresses are dissipated by the bony stability of the protracted scapula and by the posterior shoulder capsule. Scapular protrac-
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tion is a function that is often overlooked in the evaluation of posterior shoulder instability.
Evaluating the Scapula
Scapular stability and control is essential to proper shoulder rehabilitation. The anchoring position of the scapula can be estimated clinically by using the lateral side measurement test described by Kibler.4 This test measures the posterior shoulder muscles’ ability to accomplish scapular stabilization and positioning. It also serves to provide a static measurement of scapular stability in three positions. The lateral scapular slide test is illustrated in Fig. 1. These positions measure the ability of the scapular stabilizersto control the medial border of the scapula. Another method used to evaluate the efficiency of the scapular platform is manual muscle testing. Although this method is considered subjective,it often proves beneficial in the evaluation and treatment of complicated problems of scapular positioning and control.
THERAPY AND REHABILITATION
Various rehabilitationapproaches have been suggested for conservative management of impingement syndrome and rotator cuff tendinitis. Past attempts at rehabilitation have placed considerable emphasis on isolation of the supraspinatus muscle. Review of biomechanical function of this highly studied muscle reveals that it primarily acts in concert with the deltoid as a humeral elevator and secondarily assists with compression and stabilization of the humeral head in the glenoid fossa. With this knowledge in mind, one should recognize its limited biomechanical function as a humeral head depressor. The rehabilitation protocol presented here is based on strengthening the true humeral head depressors, the oblique rotator cuff muscles. By strengthening these internal and external rotators at the side, the pull of these muscles works to depress the humeral head, increase the acromial humeral interval, and decrease impingement. Strengthening the deltoid muscle is counterproductive and specifically contraindicated because its action promotes elevation of the humeral head, a decrease in the acromial humeral interval, and increased subacromial contact pressure.
CLINICAL APPLICATION
Rehabilitation of impingement syndrome should be conducted in a systematic fashion. It can be divided into three areas of concentration: decreasing inflammation, soft tissue stretching, and strengthening. Following is a synopsis of the authors’ nonoperative management of rotator cuff syndrome. Decreasing Inflammation
Patients who suffer from rotator cuff syndrome need adequate rest from the activities that have inflamed the rotator cuff. Rest is often too short. The length of time may vary from a few days to a few weeks, depending on the underlying cause of impingement. Nonsteroidal anti-inflammatory medication and a limited number of subacromial steroid injections are useful to decrease inflammation but are not a cure for the actual problem. Physical therapy modalities, such as phonophoresis or iontophoresis, can be used for a determinate amount of time (i.e., six to seven treatments). Proper position of the shoulder enhances use of these modalities be exposing the actual site of cuff inflammation. In many cases, however, the actual area of irritation cannot be exposed because of bony anatomy. If the area of inflammation can be exposed, deep friction massage and ice application can also be beneficial. Soft Tissue Stretching
Inflammation usually can be controlled within I to 2 weeks. At this point, the rehabilitation program can address specific range-ofmotion limitations that need to be corrected. Prolonged shoulder pain causes the patient to restrict instinctively the range of use and often results in an initial adhesive capsulitis at the extremes of motion. This capsulitis must be corrected before strengthening can begin. The stretching exercises that the authors use are passive and active assisted. Most can be performed by the patient independently with few follow-up visits to the therapist. Occasionally, specific forms of joint mobilization are required when patients present with adhesive capsulitis secondary to impingement. In this case, the patient may have pain related to the impingement and the adhesive capsulitis. Initial treatment should be directed at the return
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Figure 1. Lateral scapular slide test. A, Position 1, with arms in a neutral position at the side. Dots illustrate the medial border of the scapula and the spinous process, respectively. The examiner measures the distance between the two dots bilaterally. B, Position 2, the patient places hands on the hips with the thumbs pointing posteriorly.This position requires trapezius muscle activity. Again the distance is measured and is greater than that seen in position 1. C,Position 3 is one of maximum challenge to the scapular stabilizers. The humerus is abducted 90 degrees and internally rotated. Scapular stabilization requires muscular activity of the upper-lower trapezius and serratus anterior muscles. Again, bilateral measurements are taken. In symptomatic individuals, differences of more than 1 to 2 cm in either position 2 or 3 have been shown statistically to have increased pain and decreased shoulder function on the affected side.
of motion and avoiding impingement positions. Capsular stretching is directed to the return of normal roll-gliding, which is required for humeral elevation. As range of motion improves and stiffness decreases, pain levels should decrease.
When a large subacromial spur is present, initial rehabilitation goals should emphasize capsular stretching to help improve internal and external rotation. Range of motion should include specific precautions against driving previously injured subacromial tissue into the
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region of a subacromial spur. This situation can occur if the therapist insists on forcing motion out of the plane of maximal elevation. The plane of maximal elevation is the scapular plane rather than the coronal plane (abduction) or sagittal plane (flexion). The capsule of the glenohumeral joint is most relaxed in the scapular plane, allowing the highest upward excursion with the greatest ease and freedom of movement. Movements in this plane occur more naturally and with less effort during normal activities of daily living. Passive humeral movement in the sagittal plane is avoided because this movement causes increased capsular tightening, which drives the humerus into the undersurface of the overhanging acromion. Humeral distraction should always accompany passive elevation in the plane of the scapula. This distraction helps avoid further pinching of the cuff beneath the acromion. As the capsular pattern (loss of external rotation more than elevation or internal rotation) decreases, treatment progresses to strengthening of the humeral head depressors. Strengthening the Humeral Head Depressors
As the rotator cuff-deltoid force couple relationship improves, the humeral head clears the undersurface of the anterior acromion, and active forward elevation should improve. This improvement can be achieved with a specific cuff-strengthening protocol. The authors begin with isometric exercises directed toward the oblique muscles of the rotator cuff with the arm at the side. With the arm in neutral rotation at the patient's side and the elbow bent 90°, isometric external rotation is performed against the resistance of the patient's opposite hand or an inanimate object, such as a wall. The resistance is held for 10 seconds each repetition. Three sets of 10 repetitions alternating right and left arms are performed. Once these exercises are tolerated, the patient can begin light isotonic exercises using an exercise band or surgical tubing. The tubing can be tied to a doorknob, and the arm is internally or externally rotated against the resistance of the tubing. Three sets of 10 repetitions alternating right and left arms should be performed. The patient should just barely be able to complete the third set of 10 repetitions. If the patient cannot complete all the sets, the resistance is too high; likewise, if completing the task is relatively easy, the resistance is too light. When performed properly, the program should take
only about 15 minutes twice each day. If the patient is able to perform these exercises without pain, dynamic rotator cuff strengthening can begin. With the arm at the patient's side, the same exercises are performed through an arc of -30" to +30" of rotation. Emphasis should be placed on the eccentricphase of contraction (3 seconds concentric, 7 seconds eccentric). Three sets of 10 repetitions are performed alternating right and left arms as well as internal and external rotation. During all these exercises, it is imperative that the deltoid remain in a relaxed position. Abduction of the arm is to be avoided. One helpful tool in achieving this is to place a magazine between the arm and chest wall and hold it there while performing the exercises. This position requires an adduction force and eliminates any deltoid contracture. Patients should be advised that cuff reconditioning takes at least 6 weeks. In the authors' experience, however, patients should begin to experience relief from symptoms by 4 to 6 weeks. If no improvement is noted within this time frame or if the exercises are irritating to the patient's shoulder this is a good indication that the patient is not likely to respond to the exercise protocol. A longer period of rest can be prescribed, or imaging scan should be obtained to look for a rotator cuff tear. In most patients who are not active athletes, symptoms can be controlled through the aforementioned protocol. About 17% of patients tend to have a recurrence of symptoms even though an initial satisfactory result was obtained. Most respond by simply resuming the exercise program. In high-caliber athletes, eccentric cuff strengthening is the final stage of cuff rehabilitation before scapular stabilization exercises. Eccentric cuff strengthening is particularly important in patients who participate in repetitive overhead activities that require humeral deceleration. Side-lying eccentric external rotation with a dumbbell can be added with emphasis on low weight and high repetitions.The patient is instructed to avoid overloading these muscles with heavy poundage because the external rotators are weak muscles even in nonpathologic shoulders. Five to 8 lb would be considered heavy levels of resistance. Internal rotators also receive eccentric attention but require heavier poundage during training. Athletes involved in activities that require overhead movements can be progressed to high-speed isokinetics, performed in the plane of the scapula. After 6 weeks of strengthening the internal and external rotators, the patient's
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shoulder pain should have significantly improved. At this point, the patient is advised to continue exercises at home until the pain completely resolves. A maintenance program is also discussed. Patients who continue to have pain and do not begin to improve after 6 weeks of exercise are advised to return for further evaluation. Patients presenting with weakness or decreased control of the scapular positioning muscles should receive appropriate strengthening exercises, in addition to strengthening the oblique rotator cuff muscles. Strengthening the Scapular Balancing Muscles
Re-educating and conditioning the scapular musculature can have a surprisingly large impact on the correction of various impingement problems. Often the normal motor organization and force couples must be restored. In doing so, the improved scapular position and motion decrease acromial impingement and increase rotator cuff efficiency. Rehabilitation should always start at the base of the kinetic chain. Strength and flexibility deficits in the lower back and thoracic level spine should be addressed and corrected first. Trunk flexion, extension, and rotation must all be strengthened. Postural abnormalities should be addressed and corrected with proper exercises as well. Specific scapular rehabilitation can be broken down into stability exercises, closedchain exercises, and open-chain exercises. Scapular stability exercises can be started early and involve isometric exercises. Scapular shrug exercises for elevation and scapular pinching exercises for retraction are examples of isometrics that can be done. Further aid with controlling of scapular position can be obtained by taping the scapula in a retracted or an elevated position or by using a figureeight collar similar to those used for clavicle fractures. Once isometric exercises have been tolerated, closed-chain exercises should be added. These exercises have the greatest influence on reorganizing and reestablishing normal motor firing patterns for the scapula. Because these exercises are done with the arm at 909 they reproduce the normal physiologic patterns of cocontractions of the scapular stabilizing muscles and the muscles of the rotator cuff. With the patient’s hand stabilized on a wall, specific scapular maneuvers of elevation, depression, retraction, and protraction can be performed. Further loads may be placed on the scapula by progressing to push-ups, quad-
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riped and biped exercises, and press-up exercises. Finally, open-chain exercises are begun. These are more strenuous exercises and include vigorous proprioceptive neuromuscular facilitation patterns, diagonals, external rotation and retraction activities, and plyometrics. In this phase, machines may be used to allow upright rows, pull-downs, and push-ups. Because the scapula is the base from which the rotator cuff originates, some believe that a complete scapular rehabilitation should proceed any rotator cuff-strengthening exercises. A re-educated scapula allows for more normal scapular positioning and more normal patterns of activation of the rotator cuff. Furthermore, with control of the scapula comes control of acromial elevation, which decreases the chances of further impingement. Strengthening of the Prime Humeral Positioners
Once the humeral head depressorsare strong and scapular balancing has been achieved, strengthening techniques are directed at the prime humeral positioners. These techniques are directed at the glenohumeral muscles and emphasize three-component motions. Shoulder flexion and extension, adduction and abduction, and internal and external rotation are all performed against resistance. Optimizing sequencing of muscle facilitation allows the muscles to contribute their components of action consistently.This form of manual patterning closely resembles movements used in sports and overhead work activities. Each diagonal pattern is made up of two antagonistic movements. Each pattern has a major component of flexion or extension. Movement patterns can be modified to begin with isometric contractionsperformed in a limited, protected, or pain-free range. Concentric and eccentric techniques can also be used. As the rehabilitation program progresses, full range of motion is performed using smooth, coordinated linear and diagonal patterns of movement. SPECIFIC TREATMENT BY CAUSE External Anatomic Impingement
There are several causes of external anatomic impingement, including instability, acromial morphology, and anatomic abnormalities. A concerted effort must be made to delineate the exact cause before beginning a
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rehabilitation program. If the primary problem is an anatomic abnormality, such as an acromioclavicular separation with a drooping scapula, a reconstruction of the ligaments, such as a Weaver-Dunn procedure or modification thereof, is in order. Fractures of the greater tuberosity or acromion need to be anatomically reduced to avoid impingement caused by the displaced fragment. A nonunited acromial epiphysis should be recognized as a possible causative agent in impingement. Treatments can vary depending on the size of the epiphysis, the patient’s age, and the patient’s activity level. Even after the treatment of these anatomic abnormalities, the rotator cuff injury often remains. At that point, the routine physical therapy protocol outlined in this article should be used. When instability is the underlying cause, laxity of the glenohumeral ligaments allows some superior migration of the humeral head with impingement of the greater tuberosity on a relatively normal acromial undersurface. Stabilization of the glenohumeral joint is the treatment of choice in these patients. This stabilization can be done surgically when necessary but often can be accomplished with a rotator cuff -strengthening program. The initial protocol is the same one used for primary impingement, but once initial relief of symptoms has been obtained, a general shoulderstrengthening and capsular stabilization program is undertaken to control future symptoms. Once a diagnosis of external anatomic impingement is made and anatomic abnormalities have been ruled out, a conservative rehabilitation program can be started. Internal Anatomic Impingement
Internal anatomic impingement is the theory put forth independently by two investigators, Jobe and Walch (personal communication, 1991).It states that deep surface rotator cuff tears and SLAP lesions may be the result of an internal impingement process. In a lax shoulder, an abduction and external rotation maneuver can cause the humerus to sublux anteriorly. This subluxation, in turn, can cause the greater tuberosity to impinge on the posterior-superior aspect of the glenoid. The deep surface of the rotator cuff can get pinched in between these two structures causing partialthickness tearing of the cuff. Likewise, the posterior-superior aspect of the labrum can get
sheared off its glenoid attachment in a similar manner. If the labrum is detached, further instability can result. A fall or a blow to the outstretched arm in a forced elevated position can cause a similar phenomenon. The increased laxity must be addressed in the rehabilitation program primarily and the rotator cuff secondarily. Once the proper therapy has been administered for the instability, the cuff symptoms usually resolve. Functional Overload
More than any other athletically active joint, the shoulder relies on its musculature for stabilization and protection. It is subject to overuse injuries. This situation is exceptionally common at the beginning of an athletic season or after a prolonged layoff. Even simple muscle fatigue can cause a burning-type pain down to the lateral deltoid or in the infraspinatus fossa. Although the arm may fatigue easily, the pain associated with this fatigue should usually clear quickly after icing down at the end of practice. Overuse syndromes are initially treated with modification of the athletic activity to decrease irritation as much as possible. These athletes are best treated with a progressively aggressive rotator cuff -strengthening program, anti-inflammatory medications, icing, and a general shoulder stabilization program to improve strength and functional stability. Often the athletes can make modifications in training to decrease the amount of time spent performing the offending activity. For example, a pitcher having shoulder pain could continue hitting, play some first base, and limit the amount of pitching done in a practice. At times, a single massive traumatic event, such as an off-balance throw or a fall, can cause a partial-thickness rotator cuff tear. These injuries occur at either the musculotendinous junction or at the tendon-bone interface.The conservativeprogram described generally works for tears at the musculotendinous junction; however, healing times can take 5 or 6 months. The results for tears at the tendonbone interface are much less predictable. Although these can heal by conservative means, surgery is often needed. Overall, these types of overload tears are rare and are being mentioned here only for completeness. Full-thickness overload cuff tears are also possible. These tears also occur from a single violent injury. In the authors’ experience, there is no con-
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servative management for full-thickness tears of this type. Surgery usually is indicated. Intrinsic Tendinopathy
Patients who are treated for suspected intrinsic degeneration of the cuff tendons are usually older. These patients tend to be less compliant with the authors' standard rotator cuff-strengthening protocol than patients with external impingement. Because of this tendency, the authors often modify the protocol to include more frequent follow-ups with the therapist, continued use of the anti-inflammatory medications on a long-term basis as opposed to the usual 3 to 6 weeks, and a modification of the offending activities during treatment. EXERCISE EQUIPMENT MODIFICATIONS
A systemic approach toward weight training is needed when establishingguidelines for the home program. Surgeons and therapists should become familiar with the various types of equipment available in local health clubs. This familiarity enables them to provide guidelines on equipment selection and exercise modification, in an effort to prevent further shoulder injury because of improper use. Various exercise machines are designed for increasing deltoid strength, but they place the rotator cuff tendons at risk. For example, ZateraZ raises or humeral abduction with internal rotation can cause further inflammation to the subacromial tissues. Machines designed for strengthening the pectoralis and anterior chest muscles can also irritate subacromial tissues when the patient starts the exercise in the extremes of flexion, abduction, and external rotation. Equipment modifications for this particular exercise include adjustment of the weight stack, raising the top plate, and replacing the stack pin. Additional exercises, such as upright rowing, behind-the-neck pull-downs, and military press, should be completely avoided. During the bench press, the patient is advised to keep the hands in sight during this exercise and lower the bar no further than the position at which the humerus is parallel to the floor. Patients are advised that exercises for strengthening the biceps and triceps can be used for general conditioning if the exercise is
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conducted with the humerus in the adducted position, with less than 90" of forward flexion. Rowing-type movements usually can be tolerated if the patient maintains this same position.
SUMMARY
Most patients who come to the authors' office having undergone previous shoulder rehabilitation have not experienced a therapeutic benefit. Most, however, have been treated with a suboptimal program. Hot packs, massage, and ultrasound, rarely produce results. The authors rarely see a patient who understands the cause of the shoulder pain and know the goals of the rehabilitation program. These are the most basic requirements for a successful program. The protocol outlined in this article is simple, is inexpensive, and takes up little time per day. As a result, the authors have been able to maintain a fairly high rate of nonoperative success with these patients. Using these methods, patients can expect about a 70% chance of resolution of symptoms.
References 1. Bigliani LU, Morrison Ds:Relationship between acromial morphology and rotator cuff tears. Orthop Trans 10:216, 1986 2. Einhom AR, Jackson DW. Rehabilitation of the shoulder. In Jackson DW (ed): Shoulder Surgery in the Athlete. Rockville, MD, Aspen Systems, 1985, pp 103-118 3. Jobe CM, Pink MM, Jobe FW, et al: Anterior shoulder instability, impingement and rotator cuff tear: Theories and concepts. In Jobe FW (ed): Operative Techniques in Upper Extremity Sports Injuries. St Louis, Mosby, 1996, pp 164-176 4. Kibler BW. The role of the scapula in athletic shoulder function. Am J Sports Med 2:325-337,1998 5. Morrison DS, Frogameni AD, Woodworth I? Conservative management for subacromial impingement syndrome. J Bone Joint Surg Am 79:732-737,1997 6. Norkin C, Levangie P: Joint structure and function: A comprehensive analysis. Philadelphia, FA Davis, 1983 7. Perry J: Biomechanicsof the shoulder. In Rowe CR (ed): The Shoulder. New York, Churchill Livingstone, 1988, pp 1-15 8. Scovazzo ML, et a 1 The painful shoulder during freestyle swimming: An electromyographic cinematographic analysis of hyelve muscles. Am J Sports Med 19577-587,1991
Address reprint requests to David S. Morrison, MD Southern California Center for Sports Medicine 2760 Atlantic Avenue Long Beach, CA 90806