**4. Outcomes of rotator cuff repair**

reported a mean age of 59 years in a group of 586 patients undergoing arthroscopic tear repair,

Tendon degeneration and poor healing potential are exacerbated by hypovascularity, which is worsened not only with advancing age, but also with smoking, and certain other conditions [4]. Smoking has a strong dose and time-dependent association with both the prevalence and size of tears; it negatively affects the vascularity of tendons, thereby predisposing them to tears and preventing healing [3, 4]. Similarly, hypercholesterolemia has been implicated in rotator cuff disease. The mechanism here is thought to be deposition of cholesterol by-products within the rotator cuff tendons, leading to worsening of biomechanical properties of the

Genetic predisposition may also play a role. Patients diagnosed relatively early in life (before age 40) often have a family history of rotator cuff disease [3]. Particularly in irreparable tears, studies have shown expression of genes that favor fatty atrophy and fibrosis and inhibit myo-

The most commonly accepted extrinsic mechanism for rotator cuff disease was originally described by Neer in his classic article from 1972, *Anterior Acromioplasty for the Chronic Impingement Syndrome in the Shoulder: a Preliminary Report*, and has guided clinical approach to management of impingement and rotator cuff tears ever since, although validity of some of these concepts has been challenged in the recent years. Neer suggested that repetitive contact between the rotator cuff tendons and the underside of the coracoacromial arch (which includes the anterolateral acromion, coracoacromial ligament, and the coracoid) results in trauma to the tendon, which produces the clinical entities of subacromial or subcoracoid impingement, and, in its more advanced stages, tendon tears [16]. Acromial morphology (hooked versus flat) and presence of subacromial enthesophytes have also been proposed to be contributing factors to symptomatic cuff disease, and surgical approach directed at increasing the space under coracoacromial arch by way of acromioplasty and coracoacromial ligament release has been advocated [17]. However, recent studies have questioned the benefit of these procedures [18], and attention has been directed to position and dynamic function of the scapula, as a contributor to rotator cuff impingement and tears [19]. Therefore, postural abnormalities and peri-scapular muscle strength have received greater recent attention as potentially contributing risk factor that can and should be addressed in management of rotator cuff disease.

with those older than 60 being twice as likely to develop large and massive tears [13].

**Strong association Controversial or weak association**

Peripartum Hormonal changes

Dominant side Postural abnormalities

tendon and increasing the risk of tearing [14].

Heavy labor and overhead athletes (chronic wear-and-tear)

**Table 1.** Risk factors for rotator cuff pathology.

genesis [15].

Age (particularly >60)

132 Advances in Shoulder Surgery

Previous history of tear

Hypercholesterolemia

Family history

Trauma

Smoking (dose and time-dependent)

Rotator cuff repair was originally performed with open, and subsequently mini-open, techniques, which have produces good results, including restoration of shoulder strength and function. Advent and popularization of arthroscopy have allowed for a less invasive method of rotator cuff repair, contributing to decreased postoperative pain and more rapid return of motion. Other modern advancements, such as improved instrumentation, as well as stronger and more biocompatible suture and anchor materials, have led to new surgical techniques, such as a double-row rotator repair, which may contribute to better healing and possibly improved outcomes, especially for larger tears. Multiple clinical studies of arthroscopic repair have shown good to excellent results in as many as 90% of patients postoperatively, even including those with large and massive tears [20–23]. A recent systemic review and metaanalysis by McElvany et al. [24] included 108 clinical studies and showed postoperative clinical outcomes scores improved by an average of 103% of the preoperative scores. However, despite the overall good results, this same study found that 26.6% of the repairs failed to heal. Failure to heal may not (and often does not) affect short-term results, but may lead to deterioration of shoulder function after 2 years post-repair. Risk factors for failure of the rotator cuff tear to heal after surgery include preoperative fatty infiltration of the muscle, older age, and increased tear size. As many as 50% of larger (≥3 cm) tears may fail to heal after repair.

One of the most important predictors for failure of rotator cuff repair, along with tear size, is muscle atrophy and fatty infiltration (**Figure 3**). Most common system used to classify fatty degeneration of rotator cuff muscles was described by Goutallier et al. [25]. Even small and medium tears are at risk for failure after repair with as little as grade 2 muscle degeneration [26]. Shoulders with more severe (grade 3 or 4) degeneration, where more than 50% of muscle volume is replaced by fat, are at a very high risk of poor outcomes, since, even if tendon repair and healing to bone is achieved, dynamic function of the rotator cuff muscle-tendon unit remains compromised.

**Figure 3.** Fatty atrophy of the superior rotator cuff. (A) Sagittal MRI view of a right shoulder showing severe fatty degeneration (more than 50% of muscle volume replaced by fat) of the supraspinatus (SS), infraspinatus (IS), and subscapularis (SSC) muscles. (B) Arthroscopic view of the supraspinatus (SS), demonstrating severe muscle atrophy (view from a posterolateral subacromial portal in the right shoulder).

Therefore, due to poor healing potential and low likelihood of restoration of good cuff function, chronic large (3–5 cm) and massive (>5 cm) tears, especially those with Goutallier 2 or greater atrophy, may be considered irreparable. Other types of tears that are considered irreparable include tears with significant retraction of the tendon (medial to the glenoid), poor tendon quality for repair, and poor bone quality at the greater tuberosity attachment site (**Figure 4**). Attempts at repair of tears with these features should be approached with guarded expectations.

**5. Treatment options for irreparable rotator cuff tears**

The treatment of massive and irreparable rotator cuff tears is challenging. Surgical options include partial repair with marginal convergence, debridement with biceps tenotomy, graft interposition, tendon transfer, reverse total shoulder, and now superior capsular reconstruction. Partial repair of the inferior half of the infraspinatus was originally described by Burkhart et al. in 1994, with the goal restoring a balanced anterior-posterior force couple in the shoulder [27]. Multiple studies which analyzed surgery for massive cuff tears with combinations of partial repair, marginal convergence, debridement, and biceps tenotomy have shown mixed results, typically with good outcomes early on, but persistent strength deficit in elevation, and deterioration of clinical results over time. For example, Shon et al. performed partial repair and marginal convergence techniques in 31 patients and found initial improvement in clinical outcome scores, whereas 2-year follow-up showed a dissatisfaction rate of 50% [28]. Fatty infiltration of the infraspinatus was found to be a negative predictor of outcome in these patients. Graft interposition techniques to bridge irreparable rotator cuff defects have been described using autograft, allograft, xenograft, and synthetic materials. A systematic review of these techniques found a lack of high quality comparative studies. The limited studies available show improvement in clinical outcomes in all graft types [29], with allograft, xenograft, and synthetic grafts having the appeal of no harvest site morbidity, compared to autograft. On the other hand, significant inflammatory reactions have been reported with the use of xenografts as well as allografts [30], and therefore caution must be used. Just as with other surgeries for massive cuff tear, significant fatty atrophy leads to significantly lower healing rates after graft interposition repairs. Finally, interpositional grafts may need to be placed through an open approach, which runs the increased disk of damage to the deltoid muscle, potentially making subsequent revision surgery more difficult and less successful. In summary, due to lack of high quality comparative studies on the use of graft interposition for cuff repair, the potential benefits of this procedure must be weighed against the cost, risks, and potential future complications of this approach.

Superior Capsule Reconstruction: Review of a Novel Operative Technique for Management...

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Several tendon transfer procedures have been described for the treatment of massive irreparable rotator cuff tears. Tendon transfers are typically performed in younger patients without glenohumeral arthritis and good range of motion. The most common transfers used for posterosuperior tears are latissimus dorsi and lower trapezius transfers. Clinical studies show latissimus dorsi transfer provides significant pain relief after tendon transfer, whereas functional results are more unpredictable [31]. Lower trapezius transfer anatomically provides a more direct line of pull compared to latissimus dorsi transfer; however, limited clinical

Reverse total shoulder arthroplasty (RTSA) is a semiconstrained reverse ball and socket prosthesis which helps improve the biomechanical efficiency of the deltoid muscle by lengthening its lever arm. The design provides inherent glenohumeral stability and lowers the humeral head to increase deltoid tension, which allows this muscle to elevate the arm without a functional rotator cuff. While elevation is typically restored after RTSA, active rotation of the shoulder is not as easily recovered as it relies on presence of the anterior-posterior components of the cuff. Overall, clinical studies have shown significant improvements in pain, motion, and functional scores in patients treated for cuff-tear arthropathy. However, implant longevity

evidence is available to show improvement in pain and function.

Those rotator cuff tears that fail to heal or are irreparable frequently go on to a clinical condition called cuff tear arthropathy (CTA) (**Figure 2**). This is a specific form of shoulder arthritis resulting from rotator cuff deficiency. Due to the failure and absence of superior restraint, the humeral head typically migrates superiorly, and eventually articulates with the acromion. Over time this leads to wear of the acromion, destruction of the humeral head cartilage, and eventually the glenoid cartilage as well. Patients typically present with significant pain, weakness, and crepitus with range of motion, and sometimes even pseudoparalysis—severe inability to elevate the shoulder. Once advanced CTA develops, the only surgical solution available to treat it (other than fusion of the shoulder joint) is a reverse total shoulder replacement (**Figure 5**).

**Figure 4.** Massive tear of the superior rotator cuff, not amenable to repair. (A) Note poor tissue quality of the tendon stump, and retraction medial to the glenoid rim. (B) Despite extensive releases, this tendon stump could not be mobilized even to the medial margin of the greater tuberosity.

**Figure 5.** Reverse shoulder replacement in a 60 year-old man, performed for symptomatic advanced cuff-tear arthropathy.
