Tips

Stem-Based Repair of the Subscapularis in Total Shoulder Arthroplasty

Author and Disclosure Information

Management of the subscapularis is an important component of total shoulder arthroplasty. This technique article describes a stem-specific approach to repairing the subscapularis.


 

References

Subscapularis integrity following total shoulder arthroplasty (TSA) is important to maintaining glenohumeral joint stability and functional outcome. In recent years increased emphasis has been placed on the management of the subscapularis during TSA. Options for management of the subscapularis during TSA include tenotomy, release of the tendon from the bone (peel technique), or a lesser tuberosity osteotomy (LTO). Several studies have demonstrated that subscapularis integrity is often impaired with a traditional tenotomy approach.1,2 Based on these studies, a subscapularis peel or LTO approach have gained popularity.3 This technical article describes a subscapularis peel repair technique that is integrated into a press-fit anatomical short-stem during TSA.

Technique

The repair technique demonstrated in this article features the Univers Apex (Arthrex) humeral stem, but it can be adapted to other stems with features that allow for the incorporation of sutures.

A standard deltopectoral approach is used to gain access to the shoulder. The biceps tendon is released or tenotomized to gain access to the bicipital groove. The rotator interval is then opened beginning at the superior subscapularis by following the course of the anterior side of the proximal biceps and then directing the release toward the base of the coracoid in order to protect the supraspinatus tendon. Next, the subscapularis is sharply released from the lesser tuberosity. The tendon and capsule are released as a unit and a 3-sided release of the subscapularis is performed.

The humeral canal is opened with a reamer and broached to accommodate an appropriately sized press-fit component. A polyethylene glenoid component is placed and then attention is returned to the humerus.

Prior to placement of the humeral stem, 6 No. 2 or No. 5 FiberWire (Arthrex) sutures are pre-placed through suture holes in the stem (Figure 1). Four sutures are passed by hand through the medial calcar component and 2 sutures are placed through holes in the lateral portion of the stem. A 2.0-mm or 2.5-mm drill is used to create 2 holes in the bicipital groove: 1 at the superior aspect of the lesser tuberosity, and 1 at the inferior aspect of the lesser tuberosity (Figure 2A). Prior to impacting the stem, the 4 lateral suture limbs (limbs A through D) are shuttled through the holes in the bicipital groove (Figure 2B). Then the stem is impacted and secured, the final humeral head is placed, the joint is reduced, and the subscapularis is repaired (Figure 2C).

 

The 4 sutures passing through the medial calcar of the stem result in 8 suture limbs (limbs 1 through 8). Each limb is separately passed through the subscapularis tendon with a free needle, moving obliquely from inferior-medial to superior-lateral (Figure 3). Note: A variation is to pass 2 suture limbs at a time, but this technique has not been biomechanically investigated at the time of this writing.

Prior to tying the sutures, it is helpful to place a stitch between the superolateral corner of the subscapularis and the anterior supraspinatus in order to facilitate reduction. The suture limbs are then tied with a specific sequence to create a suture-bridging construct with 2 additional medial mattress sutures as follows (Figures 4A, 4B):

1 to A

4 to C

5 to B

8 to D

2 to 3

6 to 7

In this technique, each suture limb is tied to a limb from another suture. When the last 2 pairs are tied (2 to 3 and 6 to 7), they are tensioned to remove any slack from the repair and equalize tension within all suture pairs. After the sutures are tied, the rotator interval may be closed with simple sutures if desired. The patient is immobilized in a sling for 4 to 6 weeks. Immediate passive forward flexion is allowed as well as external rotation to 30°. Strengthening is initiated at 8 weeks.

Discussion

The incidence of TSA has increased dramatically in the last decade and is projected to continue in the coming years.4 In the majority of cases, TSA leads to improvement in pain and function. However, failures continue to exist. In addition to glenoid loosening, prosthetic instability and rotator cuff insufficiency are the most common causes of failure.5 The latter 2 are intimately related since glenohumeral stability depends largely upon the rotator cuff. Therefore, optimization of outcome following TSA depends largely upon maintaining integrity of the rotator cuff. While the incidence of preoperative rotator cuff tears and fatty degeneration of the rotator are not modifiable, the management of the subscapularis is in the hands of the surgeon.

While subscapularis tenotomy has historically been used to access the glenohumeral joint during TSA, this approach is associated with an alarmingly high failure rate. Jackson and colleagues1 reported that 7 out of 15 (47%) of subscapularis tendons managed with tenotomy during TSA were completely torn on postoperative ultrasound. The patients with postoperative rupture had decreased internal rotation strength and DASH scores (4.6 intact vs. 25 ruptured; P = .04) compared to the patients with an intact tendon. Scalise and colleagues2 retrospectively compared a tenotomy approach to a LTO. They reported that 7 out of 15 subscapularis tenotomies were ruptured or attenuated postoperatively. By comparison, 18 out of 20 LTOs were healed. Regardless of approach, functional outcome was higher at 1 year postoperative when the subscapularis was intact.

Recommended for You

News & Commentary

Quizzes from MD-IQ

Research Summaries from ClinicalEdge

Next Article: