Soft Tissue Failure after Arthroplasty: Rotator Cuff and Subscapularis

CHAPTER PREVIEW

CHAPTER SYNOPSIS

Rotator cuff (RTC) tears following total shoulder arthroplasty represent one of the more common postoperative complications, though the overall incidence remains low (1% to 2%). The majority of the reported RTC tears involve the subscapularis tendon, leading to pain, functional disability, and/or anterior glenohumeral instability. Strict guidelines for treatment are lacking. All contributors to instability, including component malposition, should be addressed at the time of repair or reconstruction.

IMPORTANT POINTS:

1

Early diagnosis and treatment lead to the best clinical results.
2

Late treatment may require use of reconstruction (i.e., muscle transfer, allograft reconstruction).
3

Clinical suspicion in the symptomatic patient should be evaluated with plain radiographs, computed tomography arthrogram, magnetic resonance imaging, or ultrasound.
4

Patients should be counseled regarding the potential for continued pain, functional limitations, and the possibility for further surgery.

CLINICAL/SURGICAL PEARLS:

1

The surgeon should be prepared for revision of humeral stem, humeral head, and/or glenoid component. Knowledge of previous implant and procedure essential.
2

Allograft material must be obtained in advance of anticipated reconstruction.
3

Careful mobilization of subscapularis is essential, paying particular attention to the course of the axillary nerve.
4

In chronic cases, use of Achilles allograft (static) or pectoralis major tendon (dynamic) should be considered.

CLINICAL/SURGICAL PITFALLS:

1

Infection should be ruled out in all cases of revision surgery, including intraoperative frozen section analysis.
2

Attention should be given to the humeral version, head size, and glenoid version, in addition to the obvious soft tissue problem.

VIDEO AVAILABLE:

Not applicable.

Total shoulder arthroplasty (TSA) remains one of the most successful procedures performed for disabling osteoarthritis of the glenohumeral joint, with most series reporting nearly 90% satisfactory results with mid- to long-term follow-up. Reasonable though less consistent overall outcomes have been reported with the use of hemiarthroplasty (HA) for osteoarthritis. The success of shoulder arthroplasty can be attributed to multiple factors, including proper implant placement, appropriate soft tissue balancing, adherence to sterile technique, and a closely observed postoperative therapy regimen.

However, problems can occur after shoulder replacement. Although radiographs may readily demonstrate problems such as component malposition, soft tissue failure can be harder to evaluate and yet lead to a poor clinical outcome. Improper soft tissue balancing leading to instability and cuff-deficient arthritis at the time of the initial arthroplasty are topics dealt with in other chapters. This chapter addresses the development of rotator cuff (RTC) tears after shoulder replacement (i.e., tears that were not present preoperatively) and postoperative failure of the subscapularis, taken down and repaired as part of the deltopectoral approach. Although these are somewhat different topics, dealing with progressive degenerative cuff disease (e.g., postoperative supraspinatus tears) and failure of healing of a tenotomized and repaired (but previously intact) tendon (subscapularis), there is benefit in discussing them together.

RTC tears following total shoulder arthroplasty have recently been found to represent one of the more common postoperative complications, with an incidence of approximately 1% to 2%. When symptomatic, the most common clinical findings in patients with postarthroplasty RTC tears include pain, poor shoulder motion, and glenohumeral instability. A recent systematic review has found that more than half of all reported postarthroplasty RTC tears involve the subscapularis muscle. Furthermore, rupture or insufficiency of the subscapularis muscle more often leads to anterior instability, whereas a massive cuff tear involving the supraspinatus and infraspinatus generally results in anterosuperior instability. Instability in and of itself accounts for almost 30% of all complications following TSA.

Multiple reasons have been given as to why patients may sustain postarthroplasty RTC tears, aside from any significant perioperative trauma to the upper extremity. These include previous surgical procedures involving the subscapularis (e.g., for instability), technique of RTC repair, overstuffing the glenohumeral joint, inflammatory etiology for the arthritis, insufficient soft tissue balancing, and aggressive postoperative mobilization. Much of the focus in the literature has been on postoperative subscapularis functional deficiency or rupture, though the other cuff muscles may be involved. Some recent literature has questioned the true benefit of repairing these cuff muscles in the absence of instability or significant pain symptoms, given the high failure rate and lack of significant functional improvement. Hasan et al. examined a large cohort of unsatisfactory shoulder arthroplasties and found that although RTC tears characterized 21% of the failures, the majority were minimally symptomatic and their progression followed the natural course of cuff disease. Strict guidelines for cuff repair are lacking because of the relatively low incidence of this complication, variable involvement of the cuff tendons, and inconsistent results of repair. However, in the setting of recurrent instability, all contributors to the instability, including RTC tears and component malposition, should be addressed.

CONSIDERATIONS FOR TREATMENT

It is essential to diagnose a symptomatic RTC tear expeditiously in order to have the best chance for functional improvement. Standard examination of the RTC for weakness may increase suspicion of a tear, and this may be augmented by more specific testing ( Fig. 23-1 ). Practically speaking, the sooner a tear is diagnosed, the easier the repair, because of less retraction, smaller tear size, and less surrounding adhesions. Late-recognized tears may preclude primary repair and require more advanced soft tissue reconstruction, including possible muscle transfers. As the RTC tear progresses in size and retraction, the humeral head may begin to sublux superiorly and create the “rocking-horse” phenomenon, potentially leading to glenoid loosening. Additionally, longitudinal studies of previously asymptomatic RTC tears demonstrated that a significant number will progress in size and become symptomatic, affecting the patient’s activities of daily living (ADLs). Often, however, concomitant stiffness may be present, especially in the postarthroplasty patient, making complete examination difficult and masking the presence of a tear. A delay in diagnosis may be avoided by maintaining a high index of suspicion following shoulder arthroplasty. In the setting of glenohumeral instability or frank dislocation on plain radiographs, or significantly increased passive external rotation with weak internal rotation, further evaluation should be undertaken, including computed tomography (CT) arthrogram, magnetic resonance imaging (MRI), or ultrasound.

Patients with rheumatoid arthritis and other inflammatory diseases deserve special mention with regard to RTC tears and deficiency following arthroplasty. Up to 80% of patients with RA will eventually develop RTC pathology, with about one third suffering full-thickness tears. More than half the total shoulders in patients with rheumatoid arthritis at long-term follow-up demonstrated progressive proximal migration, even without proximal migration on preoperative radiographs, or thin but intact RTC intraoperatively. No difference in pain relief, range of motion (ROM), abduction force, or function was noted between those with and those without proximal humeral migration. Another study of patients with rheumatoid arthritis, osteoarthritis, and avascular necrosis (AVN) found no correlation between proximal humeral migration following TSA and the presence of an RTC tear. The authors stated that this radiographic finding was multifactorial in etiology, including asynchronous deltoid and RTC firing, poor implant placement, and RTC tear. No difference in pain relief or function was found between those with and without RTC tears, though the authors recommended anatomic repair of the cuff if possible. Rozing and Brand found that the quality of the repair in rheumatoid patients undergoing primary shoulder arthroplasty significantly influenced clinical outcomes.

RTC tears with significant fatty infiltration more than Goutallier stage 2 have yielded inferior clinical results with primary arthroscopic repair in the native shoulder. Thus, even if a repair heals successfully, fatty infiltration and atrophy have not been shown to reverse themselves, often leaving the patient with profound weakness without pain. Edwards et al. reported no significant difference in Constant score at an average 43-month follow-up between patients undergoing shoulder arthroplasty for osteoarthritis with small, nonretracted supraspinatus tears versus those with an intact cuff. In fact, the authors found no differences in Constant score between those with repaired tears and those whose tears were left alone. Fatty infiltration of the infraspinatus and subscapularis demonstrated a strong correlation with diminished Constant scores. A patient with a massive, retracted, irreparable tear, especially with significant fatty atrophy or infiltration, and a TSA who presents with weakness or pain may be a candidate for conversion to a hemiarthroplasty or a reverse shoulder prosthesis. The limited data on the outcomes of converting hemiarthroplasties to reverse shoulders report an improvement in overall Constant score and range of motion, though with a high rate of complications and need for revision surgery ( Fig. 23-2 ).

INDICATIONS/CONTRAINDICATIONS

Given the relatively few reports on the treatment and outcomes of repair, soft tissue reconstruction, or muscle transfer following RTC tears after shoulder arthroplasty, strict guidelines regarding these procedures do not exist. Absolute contraindications to surgical intervention for symptomatic RTC tear include the presence of an active infection within the shoulder joint (which would require likely implant removal in any case) and concomitant absence of deltoid and RTC function from neurologic dysfunction. Relative contraindications include the existence of medical comorbidities that put the patient’s life at risk and poor patient nutritional status. If the patient’s medical comorbidities contributed to the RTC tear (i.e., syncope), these should be evaluated and treated during the perioperative period. Furthermore, any suggestion that a patient will be unwilling or unable to comply with postoperative activity restrictions should lead to alternative modes of treatment. Those patients who have minimal pain or have adapted to their functional limitations should also be considered for nonoperative treatment ( Fig. 23-3 ). Patients older than 70 years of age with low functional demands who present primarily with glenohumeral instability may be candidates for the more constrained reverse shoulder prosthesis.

SURGICAL TECHNIQUE

Patient Positioning

Patients undergoing repair or reconstruction of the RTC are placed in the standard beach-chair position with their upper body elevated approximately 45 degrees to the horizontal. Whether to use a padded Mayo stand on which to rest the arm or a hydraulic arm holder, as in our institution, is entirely surgeon dependent. The latter reduces the number of surgical assistants needed. Should component revision be required, adequate space must be available for extension of the shoulder joint. A head holder is employed to maintain the neutral cervical spine alignment, and the endotracheal tube should be held firmly on the side opposite the surgical site.

Surgical Technique

When faced with a revision arthroplasty secondary to symptomatic RTC deficiency, the surgeon must be prepared for any scenario. This includes the possibility of glenoid or humeral head exchange, as well as alteration of humeral stem version. Therefore, it is imperative to obtain all prior imaging studies and operative reports to ascertain the manufacturer and sizes of the current components. Further, it is likely after multiple revisions that soft tissue augmentation will be needed, and such allograft material must be obtained in advance of the procedure.

Primary repair of an acute or subacute subscapularis rupture can be accomplished through the use of bone tunnels, suture anchors, or direct tendon-to-tendon repair if sufficient lateral tissue remains. Mobilization of the medially retracted subscapularis must be performed with great care—inferiorly, the axillary nerve should be palpated and retracted during lysis of any adhesions. Release of the rotator interval tissue superiorly, including the slip of coracohumeral ligament to the upper border of the subscapularis, as well as anterior capsulectomy allow for more muscle excursion. Similarly, release of subacromial adhesions and capsular elevation from the glenoid neck relieves tension in supraspinatus and infraspinatus repairs. In chronic cases, or with re-revisions, such repair is unlikely to be successful. An Achilles tendon bone block for failed subscapularis repair after arthroplasty has been used with success, though significant motion restrictions may result. Others have reported success with modifications of a dynamic pectoralis major transfer for instability following shoulder arthroplasty, a technique based on previously described techniques of pectoralis major and minor transfers for irreparable subscapularis tears in native shoulder joints. The senior author prefers Resch’s modification in which the sternal head of the pectoralis major is rerouted under the strap muscles to give a vector like the subscapularis ( Fig. 23-4 ).