arthroscopic subacromial decompression: analysis of one- to three-year results

Arthroscopy: The Journal of Arthroscopic and Related Surgery 3(3): 173-181 Published by Raven Press, Ltd. © 1987 Arthroscopy Association of North America

Arthroscopic Subacromial Decompression: Analysis of One- to Three-Year Results

Harvard Ellman, M.D.*

Summary: Arthroscopic subacromial decompression (ASD) is a method of performing anterior acromioplasty utilizing basic arthroscopic techniques. The procedure is indicated in cases of chronic impingement syndrome that have failed to respond to prolonged conservative management. The purpose of this study is to present an analysis of the 1- to 3-year follow-up results of the initial 50 consecutive cases of ASD that I have performed. Forty (80%) of the cases had advanced stage II impingement without rotator cuff tear. Ten (20%) had full-thickness tears of the rotator cuff. Patients were evaluated pre and postoperatively on the UCLA Shoulder Rating Scale, which includes an assessment of pain, function, range of motion (ROM), strength, and patient satisfaction. Eighty-eight percent of the cases were rated "satisfactory" (excellent or good), and 12% were rated "unsatisfactory" (fair or poor). The procedure is technically demanding, and to achieve a satisfactory result the criteria of open anterior acromioplasty must be met. Arthroscopic subacromial decompression is presented as an alternative to open anterior acromioplasty in advanced stage II and selected cases of stage III impingement syndrome. Key Words: Arthro- scopic subacromial decompress ion~Acromioplas ty-- Impingement syndrome-Shoulder .

[Editor's comments: This paper by Dr. EUman was presented at the Annual Meeting o f the Arthros- copy Association o f North America in Houston in March o f 1987. It won the Richard O'Connor Re- search Award. One reviewer o f this paper noted that proper selection of cases, o f course, is very important. The same reviewer also questioned the indications for performing surgery on a 17-year-old suffering from chronic impingement syndrome that had not responded to non-operative treatment. There is one caveat that should be kept in mind, and that is the risk of making a premature judg- ment that surgery is indicated because what is being advocated is a minor surgical procedure. Pa- tients who are candidates for arthroscopic sub-

From the Department of Orthopaedic Surgery, University of California at Los Angeles, California, U.S.A.

* Address correspondence and reprint requests to Dr. Har- vard Ellman at 2080 Century Park East, Suite 1500, Los An- geles, CA, 90067, U.S.A.

acromial decompression, especially those who have been traumatized, should be given the same careful nonoperative treatment as those in whom an open procedure would be done. This paper ap- pears to push the frontiers o f arthroscopic surgery beyond anything that was dreamed o f just a f ew years ago. Too few cases o f arthroscopic subacromial decompression have been performed, and the follow-up is too short to make any long-term pre- dictions, but it is encouraging that the author re- ported so few complications.]

The impingement syndrome has been delineated in the li terature (1-4) , and the eff icacy of open anterior acromioplas ty in the t rea tment of cases re- f ractory to conserva t ive managemen t has been doc- umented (5,6). I have descr ibed a method of de- c o m p r e s s i n g the s u b a c r o m i a l s p a c e u t i l i z ing ar throscopic techniques (7,8). The pr imary objec- tives of this p rocedure are to re lease the coracoacromial l igament, resec t the undersurface of the

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anterior acromion, and debride the hypertrophic bursa. The procedure has been performed in > 100 shoulders. The initial 50 consecutive cases in this series have been followed from 1 to 3 years. An analysis of their results is the basis for this report.

METHODS AND MATERIALS

The method of performing arthroscopic subacromial decompression (ASD) is briefly reviewed. The patient is placed in the lateral recumbent position. The arm is abducted 15 °, and I0-15 pounds of continuous traction is applied. The bony landmarks (the acromion , the tip of the coraco id , and acromio-clavicular ligament) are outlined with a marker pencil. Appropriate portals are placed to permit arthroscopic visualization, accessory fluid ingress, and the introduction of a plastic surgical canulla. Orientation pins outline the attachment of the coracoacromial ligament (Fig. 1). A mechanical trimmer is introduced to remove the hypertrophic bursa and enhance visualization. Continuous dis- tention of the subacromial space with saline or Ringer's lactate as well as sustained traction are essential throughout the procedure. An electrosurgical knife is used to release the coracoacromial ligament and maintain hemostasis (Fig. 2). This re- quires the temporary substitution of distilled water

FIG. 1. Bony landmarks are outlined. The instruments (coun- terclockwise) are: accessory fluid ingress cannula, arthroscope, and surgical cannula with electrosurgical pencil inserted. Two spinal needles mark the attachment of the coracoacromial ligament.

for normal saline in order for electrosurgery to occur. The undersurface of the anterior acromion is resected with a large motorized burr. Thickened bursa underlying the acromion must be partially removed with a curette or synovectomy shaver before the burr will work effectively. The completed acromioplasty should remove the hooklike projection of the anterior acromion as well as any spurs arising from the acromion or undersurface of the outer end of the clavicle. The completed acromioplasty should meet all the criteria established for the open procedure (Fig. 3).

Postoperatively, patients are encouraged to re- sume full active range of motion (ROM) on the evening of surgery. A sling is generally unnecessary. They are advised to stretch the arm overhead while supine and to perform pendulum exercises every morning and evening for 1 min to prevent adhesion formation. No restriction is placed on activities of daily living (ADL), including driving and reaching overhead. However, strenuous repetitive overhead activit ies, including tennis and throwing, are avoided for at least 4 - 6 weeks . At that time, strengthening exercises with surgical tubing are begun, and the patient gradually resumes full activity as tolerated.

The shoulders analyzed in this report represent the initial 50 consecutive cases of arthroscopic subacromial decompression that I have performed. Forty (80%) of the patients had an established diagnosis of advanced stage II impingement syndrome with no evidence of rotator cuff tear. Ten (20%) had stage III impingement with rotator cuff tear, either very small (<1 cm) or massive (>5 cm). All had failed to respond to conservative management for a period of 6 months to >5 years.

One patient died of a brain tumor. The remaining 49 have been followed for a minimum of 1 year. The average follow-up is 16.7 months, with a range of 12-36 months. The average age was 49.5 years, with a range of 17-81 years. Males predominated over females 27 to 23. The nondominant arm was involved in only 17% of the cases.

Forty-four percent of the patients had no history of trauma. Twenty-eight percent had direct trauma, 20% had indirect trauma, and the remaining 8% had other types of injuries. Ten percent of the injuries were considered trivial, 24% were considered mod- erate, and 22% were considered severe. The remaining 44% had no injuries. Overhead activity was involved in either the occupation or avocation of 56% of these patients. The average duration of pain

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ARTHROSCOPIC SUBACROMIAL DECOMPRESSION 175

FIG. 2. Arthroscopic photograph following release of the coracoacromial ligament. Marker pins outline the margins of the ligament. The hook electrosurgical knife is apparent near the re- tracted edge of the ligament. The undersurface of the acromion is at the top.

was 28.5 months prior to surgical intervention. Night pain was a prominent complaint in 90% of the cases. The average number of steroid injections to patients in this series was 4.3, with a range of 0-30 injections.

Atrophy was present in 20% of the cases. Crep- itus was present preoperatively in 68% of the cases and persisted as a postoperative finding in 43%.

Preoperative arthrograms were not considered necessary in 36% of the cases. These were generally younger patients. A single-contrast arthrogram was carried out in 52%, and a double-contrast arthrogram was done in 12%. Twenty percent (10 cases) had positive arthrograms for full-thickness rotator cuff tears.

The results were graded on the UCLA Shoulder Rating Scale (Table 1) before operation and at follow-up. According to this schema, pain and function are each rated on a scale of 1-10, with 1 point being the worst score and 10 points the best score. Range of motion, strength, and patient satisfaction were rated on a scale of 1-5, with a maximum total score of 35 points. Results were divided into excellent (34-35 points), good (28-33 points),

fair (21-27 points), and poor (0-20 points). We used the criteria set forth by Neer (1) to subdivide the results further into "satisfactory" or "unsatisfactory" groups. According to this rating system, a patient with a satisfactory result was satisfied with the operation, had no significant pain, had full use of the shoulder with <20 ° loss of overhead exten- sion, and had at least 75% of normal strength. In the patient with an unsatisfactory result, these criteria were not met. We believe that Neer 's defini- tion of satisfactory encompasses the results that are graded by many authors as excellent or good, whereas his unsatisfactory rating would generally include results that are classified as fair or poor. In this series, a score of i>28 is considered a satisfactory result.

RESULTS

The overall results of this series were 88% (43 cases) satisfactory and 12% (6 cases) unsatisfactory (Fig. 4). Of the satisfactory group, 43% were rated excellent and 45% were rated good. The unsatisfactory group were rated 6% fair and 6% poor (Fig. 5).

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176 H. E L L M A N

FIG. 3. C o m p l e t e d ac romio - plasty. A wide area of cancellous bone is exposed fol lowing removal of the anterior undersurface of the acromion, The tips of two pins mark the anterior edge of the acromion.

The average preoperative rating was 2.8 (pain all the time, but bearable; strong medication occasionally) (Fig. 6). The average postoperative pain rating was 8.2 (occasional and slight discomfort). Preoper- ative function rating was 5.0 (restricted to light work but capable of performing most ADL). Post- operatively, the function rating was 8.8, indicating an ability to work above shoulder level with occasional slight restriction. Average ROM and forward flexion improved 12 ° . Muscle strength was evaluated on the standard scale of 0-5 , with 5 being normal. Preoperative strength was recorded as an average of 4.6; postoperatively, a negligible improvement to 4.8 was noted.

Twenty-four of the patients were active in sports prior to developing impingement; 87.5% of these patients returned to their sports activities and t2.5% did not.

Twelve cases had work-related injuries; 92% of these achieved a satisfactory result, and results in 8% were unsatisfactory. -Six of these patients re-

turned to their prior occupation, and three others returned to gainful work in an occupation that did not require strenuous overhead activity.

Debridement and decompression of rotator cuff tears Ten cases had full-thickness tears of the rotator

cuff. The results following decompression and debridement of the cuff were 80% satisfactory (8 good) and 20% unsatisfactory (2 poor) (Fig. 7). Howeve r , none of the sa t i s f ac to ry pat ients achieved an excellent rating. Debridement is re- served primarily for selected cases with unrepairable rotator cuff tears. We advise these patients that the primary goal is relief of pain and warn them that strength will not increase. This procedure is not recommended in lieu of open repair of routine full-thickness rotator cuff tears.

Arthroscopic treatment of calcified tendinitis Five cases had large calcareous deposits. Arthro-

scopic subacromial decompression was carried out



T A B L E 1. University o f California at Los Angeles shoulder rating scale

Score

Pain Present always and unbearable; strong medication

frequently 1 Present always but bearable; strong medication

occasionally 2 None or little at rest, present during light activities;

salicylates frequently 4 Present during heavy or particular activities only;

salicylates occasionally 6 Occasional and slight 8 None 10

Function Unable to use limb 1 Only light activities possible 2 AbLe to do light housework or most activities of

daily living 4 Most housework, shopping, and driving possible;

able to do hair and to dress and undress, including fastening brassiere 6

Slight restriction only; able to work above shoulder level 8

Normal activities 10 Active forward flexion

~150 ° 5 120-150 ° 4 90-120 ° 3 45-90 ° 2 30-45 ° 1 <30 ° 0

Strength of forward flexion (manual muscle-testing) Grade 5 (normal) 5 Grade 4 (good) 4 Grade 3 (fair) 3 Grade 2 (poor) 2 Grade 1 (muscle contraction) 1 Grade 0 (nothing) 0

Satisfaction of the patient Satisfied and better 5 Satisfied and worse 0

Maximum score 35 points

in conjunction with needling and removal of the calcification; 100% of this small group achieved satisfactory results (3 excellent, 2 good). Additional cases are being studied.

Failed prior surgery The procedure was carried out on seven patients

who had prior shoulder surgery. Four of these patients had prior surgery for repair of full-thickness rotator cuff tear which had failed either due to persistent pain or recurrence of the tear. Following arthroscopic surgery, one patient achieved an excellent result, and three patients were rated good. The other three patients, who had had previous opera- tions had unsatisfactory results following arthro-

FIG. 4. Overall postoperative results of the initial 50 consecutive cases of arthroscopic subacromial decompression (ASD).

scopic surgery. One of the patients with unsatisfactory results had a work-related injury and had undergone two prior open anterior acromioplasties. He failed to improve following the arthroscopic procedure. Another patient who had had a previous operation was a 58-year-old woman who had persistent symptoms following an open acromioplasty performed 15 months earlier. At arthroscopy, a pro- liferative bursitis was noted to have recurred. Bur- sectomy with removal of additional bone from the undersurface of the acromion was carried out. She was rated "good" after 1 year but slipped to a "fair" (unsatisfactory) grade at 2 years. She is the only patient in this series to date who has moved from a satisfactory to an unsatisfactory rating. The other poor result occurred in a 71-year-old man who had undergone hemiarthroplasty to the right shoulder 8 years earlier. He later developed a rotator cuff tear and had marked functional impair- ment. His preoperat ive flexion was 65 °, mostly scapulothoracic motion. He had no improvement following arthroscopic debridement and decompression.

Analysis of unsatisfactory results There were six unsat isfactory results in this

series. Three have just been described. One of the remaining three was a 64-year-old retired Veteran's Administration Hospital patient with a negative arthrogram who failed to show any significant improvement postoperatively. He was involved in an auto accident within 6 months of his surgery, and a subsequent arthrogram was again negative. He had persistent impingement pain. One year following the arthroscopic procedure, open surgery was performed. A full-thickness rotator cuff tear was found


178 H. E L L M A N

FIG. 5. Subclassification by percentage of postoperative results into excellent (34-35 points), good (28-33 points), fair (21-27 points), and poor (0-20 points).

and repaired. He has subsequently done well. An- other unsat i s fac tory result was a 22-year-old woman with posttraumatic impingement syndrome. Following surgery, she failed to achieve satisfactory improvement postoperatively, and an open anterior a~romioplasty was performed 6 months later. At surgery, it was noted that a remnant of the coracoacromial ligament persisted medially and that the anterolateral aspect of the acromion had not been entirely resected. Examination 1 year following the open procedure indicated a good result.

The final unsatisfactory result in this series was a 77-year-old woman who had a massive cuff tear with early cuff arthropathy. Preoperatively, she was unable to flex her arm beyond 60 ° and had a strength rating of 2/5. Although she is quite pleased

with the relief of pain (preoperative rating = 2; postoperative rating = 8), her limited ROM and strength precluded the possibility of achieving a satisfactory grade on our rating system.

Complications The procedure has been relatively free of compli-

cations to date. One patient developed a localized hematoma at the site of the anterior portal. This re- solved spontaneously. Three patients complained of transient dysthesias in the distribution of the dorsal digital nerve to the thumb. This developed as a result of inadequate padding at the wrist level in the traction device. There has been no case of traction neuropathy involving the brachial plexus. Ini- tially, we were concerned that bone fragments pro-

ii~iiii~!!i ¸ i ; I~I~L i ~!

FIG. 6. Comparison of preoperative pain, function, range of motion (ROM) (in forward flexion), and strength (in forward flexion) with postoperative ratings.

~rthroscopy, Vol. 3, No. 3, 1987


FIG. 7. Results following decompression and debridement of 10 cases of full-thickness rotator cuff tear.

duced by mechanical burring during acromioplasty might lead to ectopic bone formation in the bursa. This has not occurred. The constant irrigation of a large volume of fluid throughout the procedure effectively removes the bone dust. There have been no infections.

DISCUSSION

Most cases of impingement syndrome will respond satisfactorily to conservative measures. A detailed history and careful physical examination are necessary to establish the diagnosis of impingement. The dominant arm is usually involved, but less than one-half of our patients had any history of trauma. When trauma is a factor, it may be either direct or indirect.

Persons with occupations requiring repetitive overhead motion are at risk, and recreational activities that involve racket sports, throwing, or swim- ming frequently cause impingement. Nocturnal pain that awakened the patient was a prevalent complaint in 90% of the patients undergoing surgery. An excessive number of steroid injections were given to some patients in this series. In gen- eral, the relief achieved with steroid injection de- creased with repetitive use. Non-steroidal antiinflammatory agents similarly lost their effectiveness as the changes associated with chronic impingement developed.

Pain developed with overhead elevation of the extremity in every patient. The classic "impingement sign" as defined by Neer occurs during forward flexion with the scapula stabilized as elevation reaches >70 ° . Impingement pain was also pro- voked in many cases as the arm was internally

rotated and adducted as elevation approached 90%. This maneuver has been called the "impingement II sign." Pain relief following injection of a local anesthetic into the subacromial bursa (impingement test) is the most valuable confirmatory test when impingement is suspected. The pain that arises from acromioclavicular arthritis can be differen- tiated from impingement by a selective injection into the acromioclavicular joint rather than the bursa.

Plain radiographs should be taken in every case of suspected impingement. Spurs arising from the anterior acromion or the acromioclavicular joint can be visualized readily. A 15 ° caudal projection will demonstrate irregularity in the anterior acromion in some cases. The glenohumeral joint should be carefully inspected to rule out localized arthritic changes that would produce pain on motion. Bony changes develop in the presence of progressive de- generative changes in the rotator cuff (9). Cyst formation or sclerosis in the region of the greater tu- berosity suggests rotator cuff disease. A decrease in the space between the undersurface of the acromion and the superior aspect of the humeral head (acromiohumeral distance) below 7 mm may be associated with a torn rotator cuff (10-12). Preopera- tive arthrograms were not performed on some of the younger patients in this series, but every patient aged >40 years had an arthrogram prior to surgical intervention.

Differential diagnosis between instability and impingement

The differential diagnosis between instability and impingement can be quite difficult at times, but can be simplified if one recognizes that some degree of impingement will usually occur in the presence of an unstable shoulder joint. The lax capsule and weakened or overstretched musculature in a sub- luxing shoulder may permit abnormal excursions in any direction. Pain and apprehension are elicited when the arm is abducted and externally rotated if the instability is primarily anterior. Pain may be perceived at the back of the shoulder as the posterior capsule stretches and anteriorly as the head subluxes across the glenoid labrum. The anterosu- perior pain of impingement may occur as the humeral head rides forward and upward and pinches the rotator cuff against the anterior acromion and coracoacromial ligament. Posterior or inferior subluxation are less likely to simulate impingement. Injection of a local anesthetic in the subacromial


180 H. E L L M A N

space may relieve the impingement pain associated with anterior subluxation, but the apprehension and click will persist. One of the most valuable clinical maneuvers used to differentiate instability from impingement is the shoulder drawer sign. This is performed with the patient lying supine with the arm relaxed in neutral position. The examiner places one hand over the front of the head of the humerus and proximal shaft and the other hand behind. The fingers should be extended and the palm flattened to obtain maximum control. Pressure is applied in the appropriate direction in an effort to slide the head anteriorly or posteriorly in relation to the glenoid. A clicking sensation may be elicited in the presence of instability. Since the arm is not ele- vated, this test allows the examiner to isolate the findings of instability without disturbing the impingement area.

Arthroscopic subacromial decompression will generally be unsuccessful if performed when the primary diagnosis is instability. Surgical correction of the unstable shoulder, followed by therapy de- signed to strengthen and restore balance to the shoulder musculature will usually eliminate any im- pingementlike symptoms in these patients.

Technical considerations The two prerequisites for successful visualization

of the subacromial space are distension and hemostasis. An accessory fluid ingress portal must be established at the start of the procedure and main- tained throughout. Continuous traction is essential. Most patients with impingement have been taking salicylates or other nonsteroidal antiinflammatory agents for pain relief. All patients are required to discontinue these drugs at least 2 weeks prior to surgery. Bleeding and clotting studies are performed preoperatively. The ability to control bleeding with electrosurgical techniques enhances visualization and unquestionably facilitates the procedure.

The depth of bone removed from the undersurface can be estimated by a deepening technique. The large burr is used to create a crater in the undersurface of the acromion to the full depth of the burr. The large burr projects from the sheath ~3 mm. The contiguous bone is uniformly reduced to the depths of this initial burr hole. The process is repeated until the depth desired by the surgeon is achieved. A relatively bloodless field enables the surgeon to inspect the acromioplasty and smooth out any protuberances or craters that persist. A

completed acromioplasty should thin the anterior acromion across its entire width from the anterior edge to a distance at least 2 cm posteriorly. The anterior acromial hook and any spurs should be removed.

Our experience with arthroscopic surgery de- signed to relieve symptoms following failed prior surgery is discouraging. Nearly one-half of the patients in this category had unsatisfactory results. Analysis of the other patients with unsatisfactory results demonstrates the importance of performing a thorough acromioplasty as well as the need to establish a proper diagnosis preoperatively. Two of the unsatisfactory results in this series had massive cuff tears and could not achieve the satisfactory rating on our grading scale because of excessive weakness and accompanying restriction of motion. They probably belong in a "limited goals" category but are included for completeness in this report of the initial 50 consecutive cases of ASD.

There is a role for ASD and debridement of the torn rotator cuff in selected cases of unrepairable or recurrent cuff tears with intractable pain. The procedure should not be performed as a substitute for open repair of the routine cuff tear.

Needling of calcified tendinitis can be accom- plished under direct vision arthroscopically, pro- vided that the calcareous deposit is relatively large and superficial.

CONCLUSION

The results following arthroscopic subacromial decompression are comparable to those obtained with open anterior acromioplasty: 88% of the cases achieved a satisfactory result. Complications are few and morbidity is minimal. The procedure can be performed in an outpatient setting. Since no del- toid is detached, patients are able to return to ADL within a few days. Arthroscopic subacromial decompression is presented as an alternative to open anterior acromioplasty for advanced stage II and selected stage III impingement syndrome.

REFERENCES

I, Neer CS II. Anterior acromioplasty for the chronic impingement syndrome in the shoulder: a preliminary report. J Bone Joint Surg [Am] 1972;54:41-50.

2. Neer CS II. Impingement lesions. Clin Orthop 1983;t73: 70-7.

3. Hawkins RF, Kennedy JC. Impingement syndrome in ath- letes. Am J Sports Med 1980;8:151.

4. Pujadas GM. Coracoacromial ligament syndrome. J Bone Joint Surg [Am] 1970;52:1361.

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5. Post M, Cohen J. Impingement syndromeaa review of late stage II and early stage III lesions. Orthop Trans 1985;9:48.

6. Raggio CL, Warren RF, Sculco T. Surgical treatment of impingement syndrome: 4-year foUow-up. Orthop Trans 1985;9:48.

7. Ellman H. Arthroscopic subacromial decompression. Orthop Trans 1985;9:48.

8. Ellman H. Arthroscopic subacromial decompression. In: Arthroscopic Surgery; Principles and Practice, Chap. 2lb. ed by S. Parisien. NY: McGraw-Hill (in press).

9. Codman EA. Obscure lesions of the shoulder; rupture of the supraspinatus tendon. Boston Med Surg J 1927;196:381-7.

10. Ellman H , Hanker G, Bayer M. Repair of the rotator cuff. End-result study of factors influencing reconstruction. J Bone Joint Surg [Am] 1986;68:1136-44.

11. Golding FC. The shoulder--the forgotten joint. Br J Radiol 1962;35:149-58.

12. Weiner DS, McNab I. Superior migration of the humeral head. A radiological aid in the diagnosis of tears of the rotator cuff. J Bone Joint Surg [Br] 1970;52:524-7.


arthroscopic subacromial decompression: analysis of one- to three-year results

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