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Role And Outcomes of Conservative Treatment in Management of Rotator Cuff Tears: A Systematic Review

Rotator cuff tears are one of the most common shoulder disorders treated by orthopaedic surgeons, responsible in up to 85% of patients who present with shoulder pain [1]. Primarily a degenerative condition, it has a reported prevalence of around 10% in patients aged 50 to 59 years old, increasing to up to 80% in patients 80 and older [2–4]. Of these patients, up to two-thirds become symptomatic [2], resulting in pain and functional limitation. Moreover, unlike other degenerative conditions that predominantly affect older patients, societal burden of rotator cuff tears are significant, since more than twothirds of such patients present during working age [5], especially in manual labourers [6]. Rotator cuff tears have a wide spectrum of severity, ranging from partial thickness tears of a single tendon to massive tears of two or more elements of the rotator cuff which can be treated operatively or nonoperatively [7, 8]. While surgical repair is widely accepted as the standard of care for acute or acute-on-chronic traumatic tears [9, 10], the management of chronic tears remains controversial [11]. Proponents of surgical repair in these patients have often cited benefits of a reduced risk of tear progression [12], reduced cost burden and recovery time [5] and with improvements that persist in the long-term [13]. However, unlike acute tears, chronic tears usually lead to fatty infiltration and rotator cuff atrophy, which have been found to be poorly amenable to surgical repair and lead to poorer outcomes [14, 15]. Conversely, nonoperative therapies, primarily involving physical therapy and nonsteroidal anti-inflammatory drugs (NSAIDs), have been found to be effective in up to 75% of patients [16]. Systematic reviews evaluating outcomes between operative and nonoperative treatment have generally revealed mixed results, with some reviews failing to demonstrate a clear benefit to surgery [7, 17], while others have suggested surgery may be more effective than conservative treatment [18, 19] with a caveat of insufficient evidence. Hence, the current literature recommends for rotator cuff tears to be managed with analgesia and physical therapy for a period before considering surgery. Despite increasing rates of shoulder surgery [20], less than 1 in 4 patients with rotator cuff tears eventually elect to undergo surgery [16]. Consequently, there is a need for effective adjuncts to physical therapy alone, especially for patients who are precluded from surgery due to personal, cost, or medical reasons. Recently, advances in technology in non-invasive therapies, such as the use of biologic therapies [21] and electrophysiological rehabilitation, have provided a greater diversity of nonsurgical options to patients. This aim of this article is to summarize the various nonoperative modalities that can be offered to patients with atraumatic rotator cuff tears, and to evaluate how they compare with operative management. National Preventive Medicine Residency Programme, National University Health System, Singapore. Department of Orthopaedic Surgery, Singapore General Hospital, Singapore.


Methodology
A systematic review was performed, identifying articles from PubMed and Embase. The following MeSH term was used to identify titles, abstracts and keywords relevant to the review: 'rotator cuff ' AND ('treatment' OR 'therapy' OR 'management') AND 'trial'. Only articles from 1 January 2010 till the date of search (15 August 2020) were included. All articles studying the outcomes of conservatively managed rotator cuff tears in the form of a prospective randomised controlled trial (RCT) were included in this review. Studies which were not related to this topic, not published in English, included other rotator cuff lesions in the analysis other than rotator cuff tears, or had no discussion on conservative treatment for rotator cuff tears were excluded from the study. Review articles, case reports, non-RCTs, basic science studies, animal studies and cadaveric studies were also excluded from this review. The elimination of studies were performed in a systematic fashion by a single author. The characteristics and findings from included studies were synthesised thereafter in the form of tables.

Results
A total of 1172 articles were identified from the databases. After the removal of 259 duplicates, 913 articles remained for screening and elimination based on the exclusion criteria described above. 816 articles were eliminated based on the screening of titles. A further 70 articles were removed based on the screening of abstracts. After screening of full texts, 17 prospective randomised controlled trials were included within this review [22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37]. A summary of the elimination process can be found in Figure 1. The cumulative outcome of 1117 shoulders were included in the review. Out of the 17 studies, 4 studies only included patients with full thickness rotator cuff tears. 4 studies focused on comparing the outcomes of conservatively managed and surgically managed rotator cuff tears revealing inconclusive results overall. Other studies compared the outcomes of various modalities, which can be classified into physical rehabilitative modalities (physiotherapy, occupational therapy and home based therapy), electrophysiological rehabilitative modalities (eg. Transcutaneous Electrical Nerve Stimulation (TENS) and Microcurrent Electrical Nerve Stimulation (MENS)), biologic therapies (PRP, BMAC and corticosteroids) and pharmacologic therapies (eg. injectable corticosteroids). A summary of study characteristics and modalities studied can be found in Table 1. A variety of outcome variables were studies, mainly comprising of clinical outcomes (eg. active shoulder range of motion (ROM) and power), functional outcomes (eg. ASES, Constant and WORC scores), pain scores (eg. VSA score), quality of life scores (eg. SF-36 and EQ-5D scores), imaging based outcomes (utilising either ultrasound, MRI or MR arthrograms to assess tear recovery, progress and/or re-tear rates) as well as patient satisfaction scores. A summary of outcome variables assessed and study findings can be found in Table 2.

Discussion
The spectrum of options for the non-surgical management of rotator cuff tears is wide. This systematic review has synthesised the evidence regarding non-surgical options studied in prospective randomised controlled trials. From these findings, we propose a treatment algorithm for rotator cuff tears, which we will describe below. The majority of studies included within this review only studied partial rotator cuff tears. When surgical management was compared with nonsurgical management for partial rotator cuff tears, there were conflicting conclusions on the differences in outcomes of both groups. Kukkonen et al [35] and Ranebo et al [32] revealed that there was no significant difference in functional outcomes and pain scores in both groups. However, Moosmayer et al [33] revealed that at 10 years follow-up, there was a difference in functional outcomes and pain scores for patients who underwent primary tendon repair when compared to patients who underwent physiotherapy with optional secondary repair. W hen surgical management was compared to non-surgical management of full thickness rotator cuff tears, there was some evidence that functional outcomes were superior for the surgical group as well. This review thus suggests that surgical treatment can be considered for rotator cuff tears. However, non-surgical management should always be considered as the primary and initial modality of treatment for rotator cuff tears, especially partial tears. For partial rotator cuff tears, surgery should only be considered when there is evidence of failure of non-surgical treatment.

Indications for non-surgical treatment
Most, if not all, patients with suspected rotator cuff tears will receive a trial non-surgical treatment in the prelude to surgery, while the imaging is done to confirm the diagnosis. However, the conservative nonsurgical treatment remains a trial, and is not the definitive treatment. Are there patients in whom the definitive treatment of choice is nonsurgical? In our opinion, these patients can fall into one of these categories:

Patients who are not keen on surgery
Various reasons abound, patients may refuse surgery due to ignorance of the procedure, bias, fear and misunderstanding, and the costs of the surgery may be prohibitive.

Patients who are not fit for surgery
Patients requiring cuff surgery tend to be frail elderly individuals with pre-existing co-morbidities such as diabetes mellitus, ischemic heart disease and rheumatoid arthritis. Those who are ASA II and above and who are obese (BMI >35) are at risk. These effects might pose great challenges to the anesthetists in the conduct of anesthesia, airway management, and surgical positioning of patients.

Patients who may not need surgery
These include those with partial thickness tears, and full thickness tears less than 10 mm in largest dimension. In our institution, these patients are treated conservatively first. They are usually handicapped mainly by pain and stiffness, both of which are amenable to physiotherapy. Outcomes with and without repair of such partial tears with stiffness are noted to be similar [38].

Patients whose surgery may be delayed
These are usually small to mid-sized full thickness tears which are wellbalanced (Figure 2), often described as U-shaped. These patients tend to be relatively asymptomatic or tolerate the symptoms well when the tear is small, and hence present late with pain and weakness when the tear has become large or massive. In contrast, unbalanced or asymmetrical tears, often described as L-shaped or reverse L-shaped may present early with pain. These patients need surgery without delay. Patients with balanced tears can be treated with conservative treatment, albeit on a trial. In our survey of 38 patients with large tears [39], it was found that up to 24% had balanced tears and indeed, presented late after a long period of conservative treatment.

Nonoperative treatment modalities Pharmacological therapy
Analgesic medications, such as paracetamol (acetaminophen) and NSAIDs are commonly prescribed to patients with painful rotator cuff syndromes. By blocking the inflammatory process, NSAIDs are thought to reduce pain and inflammation at the rotator cuff tear site. The excellent short-term effectiveness of NSAIDs in the management of rotator cuff syndromes has been well described in the literature [40,41]. However, the gastrointestinal, cardiovascular, and renal adverse effects preclude long-term use for patients who have chronic pain. Furthermore, there has been debate on the role NSAIDs play in inhibiting rotator cuff healing. Studies in rats have demonstrated that NSAIDs result in impaired rotator cuff tendon [42] and tendon-tobone [43] healing. However, the clinical impact of these inhibitory effects are less clear, with some reporting worse outcomes [15].
However, these studies investigate tendon healing after rotator cuff repair, while there is a paucity of evidence on the effect of NSAIDs on chronic rotator cuff tears. Hence, we commonly recommend NSAIDs for patients who have acute or acute-on-chronic flares of pain, while advising against long term NSAID use due to its side effect profile and potential adverse effects on tendon healing. In patients with intractable acute pain not amenable to oral NSAID or paracetamol use, short course fixed dose opioid medications may be an option. However, its use should remain judicious, especially concerning its risks of respiratory depression and misuse.

Physical therapy
The main goal of physical therapy is to reduce pain and improve function via restoration of range of motion (ROM), shoulder strength, stability, and control. There are three distinct modalities, namely activity modification, stretching of the glenohumeral joint capsule and strengthening of the rotator cuff, scapular stabilizers, and deltoid muscles. Firstly, patients should be educated to limit aggravating activities, such as overhead or reaching actions, to prevent further injury and pain. Next, patients should be placed on a comprehensive exercise and stretching program, with both physiotherapist lead sessions and home exercise program showing good results compared with placebo [44]. Patients can be initially started on passive pendulum exercises and progressed to active-assisted exercises using the other arm or a wall as tolerated. Special attention should be placed on anterior and posterior capsule stretching, to prevent adhesions and decrease impingement [45]. Targeted strengthening of the healthy rotator cuff muscles and scapular stabilizers should be performed in a progressive manner. The use of various adjuncts, such as elastic bands and weights, have been described [46] but individual specifics are beyond the scope of this review. Strengthening of these muscles helps in improving the stability of the glenohumeral joint and preventing superior migration of the humeral head and subsequent impingement [46]. While physical therapy is an essential component to the rehabilitative treatment for rotator cuff tears, to date there have been no randomized clinical trials that have evaluated its effectiveness. The ubiquity of physical therapy for patients with rotator cuff tears makes conducting such trials difficult. Goldberg et al [47] evaluated exercise therapy alone in an observational series of 46 patients with full thickness tears. The authors found that 27 patients (59%) of patients experienced improvement, 5 (11%) remained unchanged, while 14 (30%) of patients experienced worsening at a mean follow up of 2.5 years. Kukkonen et al [35] evaluated patients with non-traumatic rotator cuff tears at 1 year, who underwent (1) physical therapy alone, (2) physical therapy and acromioplasty, and (3) physical therapy, acromioplasty and rotator cuff repair, and found no clinical differences between all groups at 1 year. A systematic review on exercise therapy in the treatment of rotator cuff impingement found that exercise is generally an effective treatment for pain reduction [48], although the results between each study are not comparable due to the heterogeneity of the various exercise programs reported. However, despite consensus that physical therapy is beneficial, there has been some evidence that patients who remain symptomatic despite therapy continue to undergo anatomic deterioration, as compared to patients who remain asymptomatic [49]. Hence, in such patients, surgery should be considered before fatty degeneration and muscle atrophy worsen.

Figure 2:
A balanced tear is one which involves largely the supraspinatus tendon with minimal or no tear noted in the subscapularis and infraspinatus.

Injections
Corticosteroid injections into the subacromial space have been shown to provide effective short-term relief of pain resulting from rotator cuff tears [7,19,45,[50][51][52]. Corticosteroids are commonly injected with a local anesthetic agent, such as lidocaine, to provide rapid pain relief, allowing patients to engage in physical therapy. By reducing the inflammatory process, corticosteroids are effective against acute tendinopathies and tears [45]. A systematic review on the effectiveness of such injections showed improved ROM of between 14 to 45 degrees, with most studies demonstrating statistically but not clinically significant improvements in the visual analog score for pain [53]. Such benefits were seen in patients regardless of the use of ultrasound guidance or anatomical approach. Regarding the longevity of pain relief, studies [52,54] have reported that while there was effective pain relief at 1 month, such benefits were not seen at 3 months. Hence, given its short term effectiveness and recent concerns regarding corticosteroid mediated tendon necrosis [55], we recommend such injections to be given for a reduction of acute inflammation and resulting pain relief, in order for patients to embark on a course of physical therapy. We do not advise for repeat injections (e.g. more than once every sixth months) in view of its potentially detrimental effects on healthy tendons. Recently, hyaluronic acid (HA) injections, while widely used for the treatment of osteoarthritis, have been gaining popularity in the treatment of tendinopathies such as rotator cuff tears. As a physiological component of synovial fluid, there has been some in vivo evidence on the efficacy of HA in treating tendinopathies. HA has been shown to suppress rotator cuff inflammation in a rat model [56], and reduced adhesions and improved tendon healing in Achilles tendon tears in a rabbits [57]. Whereas clinical evidence has been mixed, with some studies reporting improved pain and function [58], while others have reported inconclusive results [52]. In our view, more clinical trials are awaited before definite recommendations can be made on the use of HA for the treatment of rotator cuff tears.

Biologic therapies
Biologic therapies, such as the use of platelet-rich plasma (PRP), have been advocated for the treatment of tendinopathies. PRP contains a mixture of host growth factors, which has in vitro evidence of improved tendon healing and remodeling [59]. It is thought that delivery of high concentrations of growth factors to injured tendons can augment the healing process. Its efficacy has been a topic of debate, with some reviews reporting long-term clinical effectiveness [52], while other reviews has demonstrating no significant long-term improvements [21]. As presented in our results, Akan et al [29] found that PRP benefitted patients with both complete and partial tears, with improvements lasting at least 12 months. Conversely, Schwitzguebel et al [31] and Shams et al [30] reported that PRP injection did not improve lesion size, pain or functional outcomes at 6 and 12 months respectively. One possible reason for the heterogeneity of the results seen in the literature may be the high inter-individual variation in the composition of PRP [60]. Recently, there has been new evidence that injection of bone marrow mesenchymal stem cells with PRP can improve tendon regeneration, reduced pain and improve function [61], however this remains a topic for future study.

Algorithm
The central role of conservative treatment of cuff tears is illustrated in the algorithm in Figure 3. Conservative treatment may be the definitive treatment in some patients, in those who are not keen or not fit for surgery. Conservative treatment has a role to play for those who may not need surgery, like patients with small tears. In those with mid-sized but balanced tears, conservative treatment may be part of the treatment cascade.

Limitations
This review only includes prospective randomised controlled trials (level 1 and 2) which have studied at least 1 non-surgical modality for the treatment of rotator cuff tears. However, the treatment modalities Figure 3: Algorithm to illustrate the role of conservative treatment in cuff tears available are extremely diverse, not allowing for a meaningful quantitative review of the topic. Furthermore, the way the treatment was delivered varied largely from study to study (for example dosages of pharmacologics and preparation techniques of biologics given via injections). The follow-up times varied between studies as well, ranging from 1.5 months to 10 years follow up. Moreover, expectedly, some of the studies were not able to blind participants and clinicians who provide the therapy for ethical reasons.

Conclusion
There are a variety of non-surgical modalities available for the treatment of rotator cuff tears. These can be classified into pharmacologic therapies, injections, biologics, physical rehabilitation, and electrophysiological rehabilitation modalities. These non-surgical modalities should be considered as first line treatment in the management of rotator cuff tears, especially partial tears. More highquality studies are required in this area of study to allow for a quantitative review (meta-analysis and meta-regression) of the various non-surgical treatment modalities of rotator cuff tears.