Complications of Subacromial Surgery

Wesley M. Nottage, M.D.

The Sports Clinic Orthopaedic Medical Associates

Laguna Hills, California

INTRODUCTION:

The overall complication rate for arthroscopy, including all joints, has been reported by Small (1988) to be 1.68%. In the same studies, complications to subacromial decompression alone were 1.1%, with an overall shoulder arthroscopy complication rate reported as 9/1,184 cases at 0.76%.

Subsequent reports by Gartsman (1990) noted complication rates for arthroscopic subacromial decompression ranging between 2-3% with the highest rate of subacromial surgical complications reported by Curtis (1992) at 11.6%, noting complications at this level when associating shoulder arthroscopy with open subacromial surgical procedures.

This presentation will attempt to review the commonly known complications, their incidence and steps that might be taken to avoid them.

Complications may be divided into specific groups, those related to procedure, those related to technique, or those which may be considered idiopathic.

PROCEDURAL COMPLICATIONS:

Complications related to anesthetic are specifically related to the type of anesthetic administered. General anesthetics have not been without risk, noting two cases of adult respiratory distress syndrome reported by Small in 1988 following knee arthroscopy. The more common side effects are those of nausea and vomiting and the evolution, of outpatient arthroscopy and better medications, including Diprivan, as an outpatient anesthetic agent, has decreased these side effects.

Spontaneous pneumothorax has been described associated with a general anesthesia in shoulder arthroscopy without specific trauma to the chest itself, noting a correlation with people with a history of cigarette smoking.

Interscalene blocks have been specifically reported to potentially lead to inadequate blocks, direct nerve injury or pneumothorax.

It should be noted that subacromial decompression can be accomplished entirely with a local anesthetic of both the skin, bursa and joint in appropriately chosen patients (personal communication, Jolson 1996)

Equipment breakage is a rare cause of complications at the current time. As the art of arthroscopy has evolved, equipment has become less likely to fail in the operative field. Obvious metal fragments from poor fitting shaver blades is a common technical issue associated with slight bending of the tips of the blades. The breakage of arthroscopic burrs failing at the tip with a loose fragment separating in the joint has also been described.

Anchor related complications have also been noted with both loose and misplaced anchors, associated with both glenohumeral and subacromial procedures.

Nerve injuries have been described both related to surgical positions as well as to direct trauma. The beach chair position has been associated with transient posterior auricular nerve palsy (Gartsman 1993) as well as transient hypoglossal nerve palsy (Mullins, Drez, et al. 1992) . The lateral decubitus position has been associated with superficial radial nerve compression on the ipsilateral arm, as well as contralateral lateral femoral cutaneous nerve neuralgia from direct pressure (Gartsman 1993) as well as peroneal nerve palsy on the contralateral limb from excessive pressure laying on the side.

Brachial plexopathy, commonly involving the musculocutaneous nerve has been associated with excessive arm position and excessive traction weight use, which can be minimized by proper maintenance of the cephalothoracic relationship, minimizing the balanced suspension weights of the arm to 5 or 6 pounds and keeping abduction and flexion of the arm to perhaps 20 or 30 degrees.

Direct trauma to the nerves can also occur, noting the suprascapular nerve can be directly traumatized by too steep or too medial a superior portal passed through the muscle belly of the supraspinatus into the joint. A grossly misplaced posterolateral portal may traumatize the axillary nerve, and, anteriorly, the plexus is at risk whenever passing a portal medial to the coracoid. This risk can be minimized by maintaining anterior portals lateral to the coracoid.

TECHNICAL COMPLICATIONS:

A variety of technical complications have been associated with performance of shoulder arthroscopy.

Excessive amounts of fluid extravasation associated with prolonged arthroscopic surgical procedures has been noted, and can, at times, be quite impressive. However, there has been no ENG or clinical evidence of significant skeletal muscle damage or deltoid muscle damage demonstrable, as reported by Ogilvie—Harris (1990)

Three cases, however, of excessive air extravasation related to shoulder arthroscopy have been described and reported by Lee, et al. (1992) who described significant subcutaneous emphysema, tension pneumothorax and airway compression associated with what

they believed was passage of air from the superolateral portal which was suctioned into the operative field, which then was driven medially to involve the pulmonary system.

The irrigating flow chosen can also be associated with complications. Commonly used normal saline and lactated Ringers have not specifically been associated with unique complications other than that of the actual volume of fluid which may be present. Transient blindness has been reported, however, with glycine by Burkhart et al. (1990) noting his recommendation to maintain either lactated Ringers or normal saline as the fluid medium for the surgical procedure in preference over water, which causes more local cellular damage.

Vascular injury can occur commonly with the nicking of vessels during passage of portals. Making superficial skin incisions and then spreading the subcutaneous tissues away before the passage of a portal can minimize this risk.

The commonly seen bleeding in the subacromial space is usually due to laceration of branches of the thoracoacromial artery or deltoid muscular branches. This risk can be minimized by avoiding direct motorized trauma to the deltoid and using electrocautery for any coracoacromial ligament release.

latrogenic articular surface damage can occur by inappropriate portal placement with trauma to either the articular surface of the humeral head or the glenoid. More commonly, the humeral head may be penetrated directly upon entrance. Care and practice are required to properly enter the joint and to minimize articular cartilage damage.

Rotator cuff tears have been associated with portal placement as well. Norwood and Fowler reported in 1989 infraspinatus rupture which they felt was due to passage of the posterior portal through the prominent tendinous portion of the infraspinatus with rupture thereafter. They felt the portal risk was highest when moving the portal laterally and decreased as one moved the portal medially, as well as noting in internal rotation less risk of damage of the tendinous portion or the infraspinatus.

Inappropriate release of the coracoacromial ligament in cases in which there is no rotator cuff musculature to contain the humeral head will lead to the inevitable superior migration of the humeral head. This can be minimized in patients with an irreparable cuff tear by leaving a portion of the ligament intact while debriding the subacromial space, should this procedure be chosen. Incomplete release in others and may be associated with recurrent symptomatology. Rarely, an aggressive release of the anterior structures, including not only the coracoacromial ligament, may release a portion of the deltoid as well, producing the common deltoid sag seen anteriorly. Proper surgical orientation and the maintenance of proper surgical landmarks can minimize this.

The acromioclavicular joint commonly presents technical issues associated with subacromial surgery. Current thinking favors leaving the joint entirely alone if asymptomatic preoperatively or choosing complete resection rather than a minimal resection which may destabilize the joint and then produce pain. A decision should be made by the operative surgeon prior to any subacromial procedure as to the integrity of the acromioclavicular joint; either to leave it alone or to fully resect it, noting residual acromioclavicular joint symptoms is a common cause of failure of subacromial surgical procedures.

Likewise, either incomplete or excessive acromial bone resection is a common cause of failure. Inadequate bone resection, specifically leaving bone protruding beyond the anterior margin of the acromioclavicular joint, can be addressed technically and minimized or avoided; however, if present, most likely will lead to failure of the procedure. Similarly, excessive bone resection , if carried out in an pattern to produce cavitation, may lead to acromial fracture. Generally, the fractures will heal, but may heal in a displaced position, which would then provoke further impingement symptomato logy.

Utilization of a posterior acromial approach with a burr while viewing laterally will minimize the risk of cavitation, which predisposes the patient to fracture. Careful preoperative planning assessing the thickness of the acromion on outlet view prior to surgical resection will also minimize this risk.

One of the more common complications is specifically failure of diagnosis. It is important to remember that rotator cuff symptomatology is elicited from a variety of different shoulder conditions, all of which present the same complaints and very similar to examination to the patient and physician. It is important to carefully rule out instability as opposed to rotator cuff as the causative agent. Other conditions, including suprascapular neuropathy, degenerative osteoarthritis and biciptal disease may also mimic cuff disease and should be ruled out by the treating physician. Care should be taken not to miss rotator cuff tears by careful viewing of both intra-articular and bursal surfaces with debridement of synovial tissue off the superior surface of the rotator cuff before assuming the rotator cuff is intact. A marked partial thickness tear may remain symptomatic if not identified and treated; it can be identified by careful palpation by the surgeon and should be recognized and appropriately treated with either debridement and/or repair.

IDIOPATHIC COMPLICATIONS:

Synovial cyst formation following shoulder arthroscopy has been described by Moran (1989) . If a synovial cyst remains symptomatic, does not resolve, resection may be necessary. Similarly a synovial fistula may occur following acromioclavicular joint resection, particularly if the subcutaneous tissues are not closed prior to closure of the skin after an arthroscopic acromioclavicular joint resection. Care to make this closure prior to completion of the procedure minimizes this risk.

Burkhart (1990) has reported deep venous thrombosis as a complication of shoulder arthroscopy. He noted it was related to a hypercoagulable state, specifically Hodgkin’s disease in the case he reported.

Small (1988) reported two cases of reflex sympathetic dystrophy following shoulder arthroscopy, noting no provocative cause.

The risk of infection is relatively low in shoulder arthroscopy, reported between 0% (Curtis, 1992) and 0.15% (3/2,000) cases by Gartsman (1990) . These rates are for pure arthroscopic procedures; the complication rate presumably would be higher if combining arthroscopic and mini-open procedures.

SUMMARY:

One of the most common complications in subacromial surgery seems to be failure of diagnosis. Associated with this are residual symptoms in the acromioclavicular joint, in patients having undergone a subacromial decompression. Careful evaluation of the patient preoperatively and viewing the entire joint and bursa will help minimize this risk.

The most common technical error in subacromial decompression appears to be incomplete resection of acromial bone anteriorly, where it is allowed to protrude past the acromioclavicular joint. Awareness of this problem will minimize this complication.

REFERENCES:

1. Burkart, S.S., Barnett, C.R. and Synder, S.S. "Transient postoperative blindness as a possible effect of glycine toxicity." Arthroscopy, 6(2) 1112, 1990
2. Burkart, S.S. "Deep venous thrombosis after shoulder arthroscopy." Arthroscopy, 6(1) 61, 1990.
3. Gartsman, G.G. and Ellman, H. "Arthroscopic shoulder surgery and related procedures." Lee and Feiberger, 1993.
4. Gartsman, G.M. "Arthroscopic acromioplasty for lesions of the rotator cuff." Journal Bone Joint Surgery, 72A: 160, 1990.
5. Mullins, R.C., Drez, D. and Cooper, J. "Hypoglossal nerve paralysis after arthroscopy of the shoulder and open procedure with the patient in the beach chair position." JBJS 74A: 137, 1992.
6. Norwood, L. and Fowler, C. "Rotator cuff tears: a shoulder arthroscopy complication." Z~merican Journal of Sports Medicine
7. 17(6): 837, 1989.
8. Ogilvie-Harris, D.J. and Boiton, E. "Arthroscopic acromioplasty extravasation of fluid into the deltoid muscle." Arthroscopy 6(1), 52, 1990.
9. Small, N.C. "Complications of arthroscopic surgery performed by experienced arthroscopists." Arthroscopy 4, 215, 1988.