Robert Fullick, MD and David Doherty, MD
Memorial Hermann-Texas Medical Center
Advances in shoulder arthroplasty have led to increased interest with more than 50,000 surgeries performed yearly in the United States. Choosing the appropriate surgical approach and meticulous soft tissue handling during surgery has a significant effect on patient outcomes. Less invasive, rotator cuff-sparing exposures continue to be developed and improved upon; however, “classic” glenohumeral approaches are still the most commonly used for shoulder arthroplasty. Here, we describe the different approaches available while highlighting relevant considerations for each.
The patient is positioned supine with the head of the bed elevated 30⁰ to 60⁰ in the beach-chair position. The entire arm is draped free to facilitate positioning of the arm and improved exposure throughout the case. Bony landmarks should be palpated and marked prior to incision, including the acromion, clavicle, AC joint and coracoid. The incision begins just lateral to the coracoid process and extends distally along the deltopectoral groove 8cm to 10cm (Figure 1a).
Figure 1a and 1b. Making the incision and careful exposure of the cephalic vein
The cephalic vein is identified coursing in the interval between the deltoid and pectoralis major. The vein is often obscured by a fat stripe and can be located beneath. Careful exposure of the vein allows for identification of tributaries that may be cauterized or ligated (Figure 1b). Surgeon preference dictates whether the cephalic vein is mobilized medially or laterally.
Once the deltopectoral interval has been developed, the conjoint tendon, comprised of the coracobrachialis and the short head of the biceps, is visualized originating from the tip of the coracoid process. The conjoint tendon is retracted medially after release of its lateral-most border. With the conjoint tendon mobilized, the subscapularis tendon is visualized inserting onto the lesser tuberosity of the humerus. At this time, the long head of the biceps tendon is localized just lateral to the subscapularis tendon insertion and sharply traced into the rotator interval. A biceps tenotomy and/or tenodesis may be performed.
The subscapularis tendon is either tenotomized 1cm medial to its insertion or an osteotomy is performed with the subscapularis tendon reflected with a wafer of bone from the lesser tuberosity. Once the subscapularis is retracted medially, the arm is externally rotated so that the humeral head may be dislocated anteriorly and exposed. Further release of the anterior and inferior capsule is carried out directly off the anatomic neck of the humerus to minimize risk of axillary nerve injury.
The humeral head is resected, which provides visualization of the glenohumeral joint. Further capsular releases may be performed to facilitate en face visualization of the glenoid. Final preparation of the joint may then proceed as appropriate components are selected and implanted.
There are several strengths to the deltopectoral approach. First, it is familiar to surgeons who perform shoulder surgery. Second, this approach is safe given that it is a truly internervous approach. Third, it provides excellent exposure of the glenohumeral joint and is an extensile approach when exposure of the humerus is necessary.
Weaknesses of this approach include limitations in exposure and reconstruction of the posterior joint and glenoid. Secondly, the risk of neurovascular injury exists with this approach. The brachial plexus, including the axillary and musculocutaneous nerves, is at risk during exposure, soft tissue dissection and errant retractor placement. The well-documented complication of subscapularis repair failure can lead to prosthesis instability and shoulder dysfunction. Despite these limitations, the deltopectoral approach remains the most widely used for shoulder reconstructive procedures, including arthroplasty.
The patient is placed in the beach-chair position with the entire arm draped free to aid in exposure. Again, standard bony landmarks should be palpated and marked prior to incision. The incision begins over the AC joint and continues laterally over the acromion to its anterolateral border (Figure 2a). Here, the incision turns distally and continues down the long axis of the humerus.
Figure 2a and 2b. A 3-inch incision is typically all that is needed to comfortably perform the superolateral approach. Preferably, the exposure on the humeral side should not extend more than 5cm beyond the lateral edge of the acromion.
Once dissection reaches the deltoid fascia, blunt dissection is used to identify the plane between the anterior and middle heads of the deltoid. The axillary nerve is located approximately 5cm distal to the lateral acromion, but its anatomic location may vary. During the approach, it should be palpated to identify its location. Great care is required, as this approach does not use an internervous plane, and dissection and vigorous retraction risk axillary nerve damage and denervation of the anterior deltoid (Figure 2b).
After splitting of the deltoid, the subacromial bursa and coracoacromial ligament are exposed and can be debrided. Further exposure may be obtained by subperiosteal dissection and release of the anterior deltoid from the acromion. With the anterior deltoid retracted, there is excellent exposure of the humerus, the supraspinatus, long head of biceps tendon, and superior most aspect of subscapularis tendon. The long head of biceps tendon may be tenotomized and tenodesed at this time. The rotator interval is opened, and the humerus is delivered through the interval to allow for humeral head resection. An axial force applied from the elbow with the shoulder in slight extension will aid in humeral head exposure. Once the humeral head cut is made, further anterior and inferior capsular releases may be accomplished and adequate exposure of the glenoid is obtained.
This approach offers the surgeon excellent glenoid exposure, particularly the superior and posterior aspects of the glenoid. Patient positioning is similar to other approaches to the shoulder, and it represents an alternative to the deltopectoral approach for reverse shoulder arthroplasty. In addition, it provides excellent visualization of the entire rotator cuff and does not disrupt intact portions of the cuff.
It is a less extensile exposure, which can be a limitation when compared to the deltopectoral approach. In addition, difficulty with exposure and removal of inferior osteophytes from the anatomic neck of the humerus can be encountered. Further drawbacks include risk of axillary nerve damage and failure of the deltoid repair after release from the anterolateral acromion. These may lead to poor patient outcomes. This approach may also lead to an increased risk of glenoid component malpositioning, i.e., superior tilt of the glenoid baseplate, and loosening of glenoid components, especially in reverse shoulder arthroplasty.
Rotator Cuff Sparing Approach
The patient is placed in the beach-chair position. The author prefers elevating the head to 70deg, which is more vertical compared to standard total shoulder arthroplasty. All bony landmarks should be palpated and marked prior to incision. The incision begins 1-2cm lateral to coracoid tip. This may aid in visualization of the rotator interval and glenoid to follow. The superficial and intermediate portions of the dissection are similar to the deltopectoral approach. The cephalic vein is identified and retracted. The conjoint tendon is identified and retracted medially. A sharp Homan retractor is placed superior to the coracoid process and the CA ligament is often incised improving exposure of the rotator interval.
Figure 3. Detailed operative technique
The rotator interval is excised and a biceps tenotomy is completed. The tenodesis may be performed at the surgeon’s discretion. The subscapularis is then exposed in its entirety, and the leash of vessels at its inferior border is ligated. The inferior most portion of the subscapularis muscle belly is released and elevated from the humerus starting just superior to the vessels. This creates a window that provides the exposure necessary for an adequate capsular release and removal of inferior osteophytes from the humeral head. The capsule is released from anterior to posterior with progressive shoulder flexion and external rotation to provide inferior exposure. Care is taken to palpate the axillary nerve to define its location and course.
Attention is turned to exposure of the humeral head through the rotator interval. Retractors are placed beneath the supraspinatous along the posterior humeral head and deep to the subscapularis along the anterior anatomic neck to expose the humeral head through the interval. Adduction, extension, and external rotation bring the humeral head into the rotator interval for exposure and resection. Once the humeral head is resected, the humerus is prepared in standard fashion and further inferior and anterior capsular releases are performed. Retractors are repositioned allowing for glenoid completion. Lastly, the humerus is trialed and implanted through the rotator interval. The rotator interval is closed with interrupted sutures. The inferior subscapularis and capsule are not repaired (Figure 3).
This technique uses several features of the deltopectoral approach, and the anatomy is familiar. This is a muscle sparing approach that minimizes subscapularis tendon damage, hopefully leading to fewer subscapularis complications post-operatively compared to tenotomy or osteotomy. This allows for early active shoulder motion with less risk of subscapularis failure. Additionally, there is less extreme positioning of the arm in external rotation and abduction that may pose less risk of stretch injury to the axillary nerve and brachial plexus during glenoid exposure.
This approach is associated with a steep learning curve. Poor exposure can cause component malpositioning and specials retractors may be required for adequate visualization. Currently, this technique should be performed by experienced shoulder surgeons. It is best suited for primary arthroplasty without excessive glenoid erosion or bony deformity.
Shoulder arthroplasty techniques continue to evolve. Soft-tissue-sparing approaches including rotator cuff sparing and transhumeral techniques continue to advance. Ultimately, the goals of current research are improved patient outcomes and implant survivorship. Before each surgery, the surgeon should consider relevant anatomy and pathology and choose the approach that provides highest likelihood for success.