54.1 Goals of Procedure

Subscapularis tendon failure after anatomic total shoulder arthroplasty (TSA) is a potentially devastating complication that can result in serious pain, disability, and even component failure. These complications can occur early in the postoperative period as a result of trauma or failure of primary healing. They can also be late-onset problems caused by trauma. Recognition and expeditious appropriate treatment are critical for successful return to function after this complication.

While the complications of acute and chronic rotator cuff injury after anatomic TSA have been well described in the literature, very little has been published on the topic of subscapularis failure after these procedures. ¹ Most current literature about this topic centers on the technique of subscapularis release and repair during index TSA and only alludes to results of different types of reconstruction techniques including tendon-to-tendon repair, tendon-to-bone repair, and lesser tuberosity osteotomy. ^{2 – 5} The reported failures include lack of primary healing and subsequent progressive subscapularis muscle atrophy in as high as 44% of patients in some series. ³ In most of these series, the results in patients who had a tuberosity osteotomy for exposure during the index procedure had the fewest number of acute failures; however, all three techniques had some subscapularis failures. ^{4 – 5} To date, in a review the literature, there are no reports on the treatment of subscapularis failures after TSA.

54.2 Advantages

Subscapularis failure after TSA can be a devastating complication that can lead to failure of the index procedure and can also compromise further surgery. For this reason, it is of critical importance to recognize this complication and treat it early. Historically, in acute cases, treatment would center upon attempted repair of the primary closure with or without augmentation graft techniques. In cases with later-onset subscapularis failure, tendon transfers and tendon graft procedures have been described; however, in the present era reverse shoulder arthroplasty (RSA) is now the primary revision option in these cases.

In this chapter, we will define the issues of subscapularis failure after TSA including proper diagnosis, treatment options, and techniques.

54.3 Indications

The diagnosis of subscapularis failure may be subtle involving the sudden development of internal rotation (IR) weakness or a sense of anterior instability after TSA. It may present more acutely as instability after a traumatic event. In either situation, the clinician must recognize the possibility of this complication and perform a careful history and clinical examination to document it. In any patient with a TSA who presents with any history of instability or loss of IR strength especially after sudden trauma, a subscapularis failure must be considered and appropriate workup carried out. These patients will often exhibit IR weakness, anterior instability, and excessive external rotation (ER). Depending upon the time after index surgery, tests for subscapularis function including the belly-press test, lift-off test, and the bear-hug test (all described in previous chapters) may all be positive.

In cases with obvious anterior instability or subluxation, standard X-ray films ( Fig. 54.1 ) may be diagnostic; however, in more subtle cases MRI and CT arthrograms and even ultrasound techniques may be more helpful in diagnosis of re-tears of the subscapularis tendon and/or associated muscle atrophy ( Fig. 54.2 ).

Patients with acute subscapularis tendon failure after anatomic TSA can be considered for primary repair based on the clinical presentation, X-rays, and more sophisticated imaging such as MRI and CT scans. In the more chronic situations with significant subscapularis muscle atrophy and especially in patients older than 65 years, it is best to consider revision to reverse shoulder replacement.

54.4 Contraindications

In older patients with long-standing subscapularis failure after anatomic TSA, primary repairs should not be considered. Patients with more acute subscapularis tendon failures that are of more than 3 months’ duration are also at great risk of failure after primary repair and should also be considered for revision to RSA in most cases. In some younger and higher demand patients even 3 months after failure, the surgeon may consider a primary repair later in the course of the complication with or without augmentation with some allograft tissue; however, the patient must be properly counseled about the risk of re-failure.