Authors: Erin Sullivan, Solomon Bhandari-Young, Aimee Kamat, Thomas M. Best
Categories: Original Articles
Source: Orthopedic Nursing
Authors: Erin Sullivan, Solomon Bhandari-Young, Aimee Kamat, Thomas M. Best
Adhesive capsulitis (AC), commonly known as frozen shoulder (FS) or arthrofibrosis, is a condition characterized by progressive stiffness, loss of motion, and pain in the shoulder joint. It is a relatively common diagnosis that often has a prolonged clinical course, significant patient morbidity, and high socioeconomic burden. The etiology involves a combination of intrinsic and extrinsic factors leading to inflammation, fibrosis, and subsequent joint capsule contracture. Although many studies have examined various treatments for this condition, there is currently no consensus on an optimized treatment algorithm. This paper synthesizes current knowledge and emerging research to provide insights into the effective management of adhesive capsulitis, emphasizing the importance of early diagnosis and individualized treatment plans.
Shoulder pain is estimated to be the third most common musculoskeletal complaint in the United States, and >50% of patients presenting with shoulder pain will continue to have chronic symptoms more than 6 months after the initial visit (Lucas et al., 2022). Adhesive capsulitis (AC) describes a pathological process in which the body forms excessive scar tissue or adhesions across the glenohumeral joint, leading to pain, and significant stiffness and dysfunction in the shoulder. It is commonly referred to as “frozen shoulder” due to the profound global loss of motion associated with this condition. It is often a debilitating problem that typically occurs spontaneously (primary/idiopathic adhesive capsulitis), but can also occur following shoulder surgery, trauma, or neurological conditions such as post-CVA/stroke/Parkinson’s disease (secondary AC) (Le et al., 2016).
Adhesive capsulitis has an overall prevalence of 3–5% in the general population and most commonly affects patients in the 4th to 6th decade, with a very strong female predominance (an estimated 65–70% of diagnosed cases are in women) (Le et al., 2016) (Barth et al., 2022). The non-dominant shoulder is affected in approximately 65–70% of cases. However, 15% of the time the patient will subsequently develop adhesive capsulitis in the contralateral shoulder within 5 years of the initial diagnosis (Mezian et al., 2023). There is a strong association between AC and diabetes mellitus (both IDDM and NIDDM) as well as autoimmune thyroid disorders (both Graves disease hyperthyroid and Hashimoto hypothyroid) with some studies demonstrating an overall incidence of 20% in female patients >40 years of age with a concurrent diagnosis of diabetes (Le et al., 2016). A higher hemoglobin A1c (indicating poor glycemic control) increases the incidence and severity of AC in patients with diabetes (Chan et al., 2017). There has also been recent research that has shown a correlation with the rapid decline in estrogen levels seen in menopausal women which may be a trigger or a risk factor for AC. Jocelyn Wittstein, MD and her research team at Duke have recently presented and published a retrospective study that showed a decreased risk of AC in women who took hormone replacement therapy (HRT) vs those who did not (Saltzman et al., 2023). Finally, there is also an increased incidence seen in patients who are HLA-B27+, which is believed to trigger a chronic inflammatory response (Prodromidis & Charalambous, 2016) [Table 1].TABLE 1.Risk Factors Associated with ACSex: FemaleAge: 40–60 yearsThyroid disorders (Graves hyperthyroid or Hashimoto hypothyroid)Diabetes: both Type I and Type II, poor glycemic controlRecent history of shoulder surgery/shoulder immobilizationHistory of contralateral adhesive capsulitis diagnosisRecent history of menopauseDupuytren’s contracture, HLA B27+Hyperlipidemia
There is recent evidence associating an overall increase in the incidence of shoulder pain from AC secondary to the COVID-19 virus. While it is widely accepted that infection with SARS-CoV-2 can have multiple extrapulmonary long-term complications, data assessing the musculoskeletal complications associated with the virus are just starting to emerge (Ramani et al., 2021).
Ascani et al. (2021) hypothesized that both direct effects of the virus and indirect effects of the host systemic inflammatory response to infection may contribute directly to the secondary development of AC. The inflammatory response seen in AC is very similar to that seen in COVID-19, and synovial cells in the shoulder joint may be targeted by SARS-CoV-2. A recent study has found a nearly 35% increase in the number of AC cases diagnosed in an 18-month post-pandemic period when compared directly to the same time period before COVID-19 (Disser et al., 2020). A more recent study in Ireland noted similar findings with a 39.8% increase in AC during the COVID-19 pandemic from March 2020 to Jan 2021 (Demyttenaere et al., 2022). De Mello et al. (2023) likewise found that the incidence of AC, Type I IDDM, Hashimoto thyroiditis, and Dupuytren’s all increased significantly between 2020 and 2022. Saremi et al. (2022) found that COVID-19-infected patients typically experience adhesive capsulitis at a younger age and experience more severe shoulder pain. This recent increased incidence of AC in younger patients with concurrent or recent COVID-19 highlights an even greater need for heightened awareness and early diagnosis and intervention to prevent chronic shoulder pain and stiffness.
The clinical diagnosis of idiopathic AC relies on the detection of a global decrease in active and passive glenohumeral range of motion (on physical examination), absence of full-thickness rotator cuff tear on imaging, and normal joint space on plain radiographs (no significant osteoarthritis/OA). However, the diagnostic criteria for AC are often vague and non-specific, and there is frequent significant clinical (and sometimes radiographic) overlap with rotator cuff tendinopathies and pathology, glenohumeral instability, impingement, and primary/secondary glenohumeral osteoarthritis. Loss of passive external rotation is often considered the most characteristic finding at physical examination (Kraal et al., 2019). Despite the many diagnostic labels and familiar patterns of clinical presentation seen with AC, there are currently no formally recognized diagnostic criteria (Millar et al., 2022).
MRI findings that are consistent with a potential diagnosis of AC include capsular thickening, a hyperintense T2 signal and contrast enhancement in the axillary capsule and rotator interval, loss of the axillary recess, thickening of the coracohumeral ligament (CHL), and obliteration of the subcoracoid fat triangle (Park et al., 2016) (Figure 1). MRI findings can sometimes correlate with the degree of loss of ROM, intensity of pain, and clinical phase of AC (Chellathurai et al., 2019). MRI can also assess for concurrent shoulder pathologies such as rotator cuff tears, subacromial bursitis, and labral lesions which may co-exist or need to be differentiated from adhesive capsulitis. Nevertheless, MRI is not a diagnostic standard and clinical presentation and history remain the cornerstone for diagnosis.Figure 1.Sagittal oblique MRI of the shoulder demonstrating capsular thickening and reduced joint volume consistent with adhesive capsulitis.
While idiopathic AC is usually considered a self-limited disease that typically resolves between 1 and 3 years after onset, several studies have now shown that up to 35% of patients can have persistent symptoms with more protracted symptomatology and significant long-term range of motion (ROM) limitation (Shanahan et al., 2022) (Oh-Park et al., 2023). It also limits overhead activity, can significantly limit many routine activities of daily living (ADL’s), and can impair quality of life for a substantial period of time (Koh, 2016). Functional impairments caused by adhesive capsulitis consist of limited reaching, particularly during overhead (e.g., hanging clothes, reaching for shelf, dressing or fastening clothes) or to-the-side (fastening seat belt) activities. Patients will also often have significantly restricted shoulder rotations, resulting in difficulties in personal hygiene, clothing, and brushing their hair. Another common complaint from patients with AC is sleeping difficulty, and this is particularly common in the painful initial “freezing” stage (Shafqat et al., 2024). Another common concomitant condition seen with adhesive capsulitis is neck pain caused by overuse of the cervical muscles to compensate for the loss of shoulder motion.
**Freezing—**Painful Initial Phase [up to 9 months]: Acute inflammation in the shoulder joint capsule, pain that can be severe and is often worse at night; acute and often extensive synovitis located throughout the glenohumeral joint.**Frozen—**Stiff Phase [4 months to 20 months]: Markedly decreased ROM in the affected shoulder in all planes of motion, thickening, and contracture of the joint capsule, and formation of collagenous tissue surrounding the joint, reducing the overall volume. Chronic inflammation is often observed in the synovial fluid.**Thawing—**Improvement in ROM [5 months to 36+ months]: gradual reduction in synovitis and inflammation with gradual improvement in objective ROM and subjective pain scores/functionality.
This three-phase classification system has been questioned recently due to the large percentage of patients that do not have full resolution of symptoms at the end of the “thawing” stage and a potential need for a post-thawing/chronic frozen shoulder category has been discussed (Millar et al., 2022). There is additionally some overlap between the stages, and the timeline for resolution of symptoms varies greatly.
The management of AC lacks a defined evidence-based model, with a wide range of treatments available. Treatment varies significantly depending on the stage of the disease, the severity of symptoms, the age of the patient, and any potential comorbidities. An individualized multidisciplinary approach provides the best outcome for AC patients (Karateev et al., 2023). Although extensive research has been conducted on the various treatment options such as physical therapy, medications, surgery, orthobiologics, and regenerative therapies, the ideal treatment algorithm remains unknown (Challoumas et al., 2020).
Physical therapy (PT) is considered a cornerstone treatment for AC with the primary goals of reducing pain, increasing range of motion (ROM) and restoring shoulder strength and function. Adhesive capsulitis seems more responsive to physical therapy during the early stages—i.e. stages 1 and 2; therefore, accurate and timely diagnosis in the first weeks to months may be critical to successful patient outcomes with PT. Clinicians need to be attentive to early loss of range of motion, particularly loss of active and passive glenohumeral external rotation (Mezian et al., 2023).
Modalities such as heat, ice, transcutaneous electrical nerve stimulation (TENS), and dry needling can all be used as adjuvant therapies in the treatment of AC. Dry needling has been used with increased frequency for shoulder pain diagnoses including AC (Pérez-Palomares et al., 2017). The technique involves inserting a fine (30–40 mm gauge) monofilament needle into the skin and subcutaneous tissues without injecting any substance. The goal of dry needling is to release or inactivate the trigger points to relieve tension/pain and improve ROM. Although more studies are needed (especially specific to adhesive capsulitis), early evidence has shown good efficacy (Reynolds et al., 2023; Kalia et al., 2021). There is an ongoing randomized-controlled clinical trial by Duke University (2024) assessing the effectiveness of dry needling for adhesive capsulitis by comparing a standardized dry needling with PT exercises and a control.
Dry needling with electrical stimulation (DNES) is another increasingly popular intervention used by physical therapists when treating musculoskeletal shoulder pain (Figure 2). After the needles are placed, electrical stimulation is applied through the needles. The mild electrical current assists in stimulating the muscle fibers, leading to further relaxation of tight muscles and enhanced pain relief. It can also help in promoting better muscle function and reduce inflammation. Joint mobilization and passive/active stretching exercises are also key parts of a PT treatment program for AC. Typical PT regimens are found to vary in both frequency and overall duration, across both practice and clinical research. A common frequency is three sessions a week for up to 12 weeks, though patients may often benefit from an even longer course (Kirker et al., 2023).Figure 2.Dry needling with electrical stimulation (DNES) applied to the periscapular/rotator-cuff region for AC management.
Acetaminophen and nonsteroidal anti-inflammatory (NSAID’s) medications are common first-line nonsurgical treatments for adhesive capsulitis, but there is little evidence for their long-term effectiveness. With diminished inflammation and pain, AC patients may be better able to tolerate physical therapy and range of motion exercises with oral acetaminophen or and NSAID (Motrin/Ibuprofen). NSAID’s alone have not demonstrated efficacy in patients with prolonged shoulder symptoms. They have not been shown to improve pain or overall function when compared with placebo (Hsu et al., 2011). There is a paucity of high-quality studies discussing the utility of NSAID’s in comparison to other drugs and treatments for adhesive capsulitis (Pandey & Madi, 2021).
Corticosteroids have often been considered a viable option in treating AC, especially during the early stages where acute inflammation is thought to predominate. Fluoroscopic or ultrasound assisted intra-articular steroid injections are generally well tolerated in the shoulder and it is a frequent initial treatment recommendation for patients with suspected adhesive capsulitis. One clinical trial conducted by Prestgaard et al. (2015) compared pain reduction between two test groups receiving corticosteroid injections (intra-articular injection and rotator interval injection) to a third control group receiving placebo (saline) injections and found that pain scores were significantly improved in the groups receiving the corticosteroid. Similarly, Ranalletta et al. (2015) compared the use of oral NSAIDS vs intra-articular injected corticosteroids (betamethasone) and found significantly improved pain and function scores at 6 and 8 weeks. However, by 12 weeks, no statistical difference was noted between the two groups. The lack of sustained long-term improvement with intra-articular corticosteroids has also been shown in previous studies (Song et al., 2014) (Koh, 2016).
Side effects of corticosteroids include the possibility of iatrogenic tendon rupture, systemic hyperglycemia, skin hypopigmentation and atrophy, joint infection, potential progression of joint osteoarthritis, periarticular calcifications, and localized subcutaneous atrophy (Shah et al., 2019) (Kamel et al., 2023). Repeated intra-articular corticosteroids should be avoided as there has been recent evidence suggesting chondrotoxicity and a higher risk for progression of osteoarthritis (OA). Research from the Osteoarthritis Initiative found that patients who had received intraarticular knee joint injections of corticosteroid had 3.2 higher odds of showing radiographic progression of osteoarthritis than those who did not receive injections; the odds were higher at 4.67 in patients who received multiple steroid injections (Zeng et al., 2019). It can be theorized that a similar finding would be found in the shoulder but more research is needed. Ideally, a randomized double-blind clinical trial should be performed to gain insight into the pathophysiology and natural history of potential adverse joint events with intra-articular corticosteroids injection.
Hyaluronic acid (HA) can be administered as an intra-articular injection to the shoulder for the treatment of adhesive capsulitis or osteoarthritis. Hyaluronic acid is a viscoelastic entity that occurs naturally in connective tissues and synovial fluid. It is postulated to act as a shock absorber and lubricant when administered via intra-articular injection (Honvo et al., 2019). While the use of hyaluronic acid (HA) is FDA-approved for intra-articular injections for osteoarthritis, it’s use for treating adhesive capsulitis is currently not FDA approved at this time. However, Mao et al. (2022) recently did a systematic review and meta-analysis of randomized controlled studies looking at the use of HA in patients with adhesive capsulitis. They found that intra-articular HA injections did improve pain scores and improved external rotation in patients with AC when compared to control groups. Oh et al. (2021) did a comparative analysis of IACS (intra-articular corticosteroid) vs IAHA (intra-articular hyaluronic acid) vs a combo approach where both were injected simultaneously. They found that simultaneous injection provided the best reduction in pain scores, improved ROM and overall function up to 3 months post injection. However, there was no statistically significant difference between the groups long-term at 3 months and 6 months post injection. Further studies combining hyaluronic acid and other therapeutic injectables (including biologics) is an area that needs further exploration and research.
Shoulder hydrodilation has been utilized as a potential treatment for AC over the past 2–3 decades and involves arthrographic distension of the glenohumeral joint (performed with saline ± steroid) under ultrasound or fluoroscopic guidance to cause stretching or rupture of the joint capsule with a subsequent increase in joint ROM. A randomized trial involving 86 patients compared hydrodilation to both corticosteroid injection and physical therapy alone. While there was improved ROM in the hydrodilation group at 6 weeks and 3 months—at 6 months, there was no statistical significance in both passive and active ROM between the three groups (Yoon et al., 2016). A recent systematic review of 452 studies (total of 2623 participants) concluded that hydrodilation leads to at least a transient improvement in shoulder ROM in patients with AC when done in combination with aggressive adjuvant PT-guided mobilization exercieses and stretching (Poku et al., 2023). Another recent study in Japan assessed shoulder hydrodilation specifically targeted at the contracted coracohumeral ligament in patients with AC and found statistically significant improvement in both pain scores and in planes of motion both short and long term (Kimura et al., 2022).
In the past, patients with suspected AC were often brought to the OR for shoulder arthroscopy and manipulation under anesthesia (MUA) to lyse adhesions and improve ROM. However, over time, it has been shown that this previously commonly performed procedure can have several complications, including nerve injuries, rotator cuff tears, humeral fractures, complex regional pain syndrome, and iatrogenic increased joint stiffness post-operatively. Accordingly, this procedure is performed far less frequently today (Grant et al., 2013). After MUA, patients previously were admitted to the hospital and received intense physical therapy and continuous passive motion (CPM machine). Currently, however, patients undergoing MUA are sent home and will need to have aggressive PT to maintain the increased ROM post-operatively. Although there are serious iatrogenic risks associated with MUA listed above, the most common one is recurrent joint stiffness (Uppal, 2015).
Arthroscopic capsular release (ACR) is another option for AC patients who have a persistent loss of range of motion despite other conservative treatments (PT, intra-articular injection, etc.). Although less invasive treatments are recommended for the first line of treatment for AC, there has been recent research demonstrating improved surgical outcomes when minimally invasive ACR was done earlier in the course of joint stiffness/contracture. AC patients with a duration of symptoms <10 months made greater improvements in internal and external rotation with ACR when compared with patients who had a longer duration of symptom (Rizvi et al., 2019). Rangan et al. (2020) published a large randomized multicenter three-arm study comparing PT to MUA and ACR for AC and found no long-term statistical difference in pain, ROM, or function scores between all three interventions at 12 months post-intervention.
Orthobiologics, including platelet-rich plasma (PRP) and adipose/bone marrow-derived mesenchymal stem cell therapies, have gained popularity in recent years. They may contain autologous or allogenic cells, proteins, cytokines, or growth factors (Centeno & Pastoriza, 2020). These treatments aim to use the body’s natural healing processes to promote tissue repair, reduce inflammation, and improve joint function and ROM. PRP is the most widely used orthobiologic (Budhiparama et al., 2024) and is created by harvesting autologous whole blood and centrifuging it to concentrate the platelets (Figure 3). This solution is rich in anti-inflammatory and anabolic proteins and is believed to be chondroprotective leading to its use in conditions such OA and AC (Cook & Smith, 2018). Although many clinical studies have shown promising results with PRP in the treatment of various orthopedic conditions, there are significant inconsistencies regarding the standardized preparation of doses, including the optimal absolute number of platelets, their concentration and methods of administration (Bansal et al., 2021). A 2017 systematic review concluded that only 16% of published clinical studies provided any quantitative metrics of the composition of PRP delivered (Chahla et al., 2017). This makes interpretation of any PRP study very difficult and the clinical efficacy of PRP therapy in orthopaedic surgery remains an open and ongoing debate. While PRP injections are widely used for various musculoskeletal disorders including tendinopathies and OA, its use in treating AC is still in the investigational stage.Figure 3.Syringe of platelet-rich plasma (PRP) following centrifugation, prepared for musculoskeletal injection.
The use of allograft amniotic fluid or human amniotic membrane (hAM) as part of regenerative medicine is a growing area within orthobiologic treatments (Huddleston et al., 2020). Amniotic fluid, naturally found in the amniotic sac during pregnancy, plays a crucial role in protecting the developing fetus. It is collected from consenting mothers during planned cesarean (C-section) births without harming the mother or baby. Donors undergo extensive screenings for communicable diseases, and the collected tissue undergoes thorough processing (cryopreservation, micronization, lyophilization, sterilization), resulting in a “decellularized” injectable substance. This innovative treatment option is gaining popularity for patients suffering from pain due to injury, inflammation, or degeneration. The unique anti-inflammatory and anti-scarring properties of this birth tissue have encouraged its use it for multiple clinical applications in ophthalmology, periodontal procedures, non-healing skin ulcers and burns, and many surgical reconstructive procedures to optimize healing (Tighe et al., 2020; Fénelon et al., 2021).
Orthopaedic surgeons and pain management physicians currently use amnion allograft injections for several conditions, including osteoarthritis, rotator cuff tears, and tendinopathies (Anderson et al., 2021). Human placental tissue has been reported to contain biochemical and immunologic properties that play key roles in regulating the inflammation-healing cycle. The use of AMUC (amniotic membrane/umbilical cord allograft) tissue for shoulder pain typically involves a single image-guided intra-articular injection into the glenohumeral joint space (Ackley et al., 2019). However, there are newer techniques such as the RELIEF® (Real-time Echolocated Interventional Epineural Fibrolysis) treatment where AMUC allograft is mixed with a proprietary IV solution and injected extra-articularly into multiple areas of the fascia surrounding the shoulder joint under ultrasound guidance (Figure 4). The RELIEF® treatment also incorporates a hydrodissection technique, using the needle and injected fluid to directly disrupt scar tissue and adhesions within the fascia while simultaneously delivering the amnion allograft.Figure 4.Ultrasound-guided hydrodissection with amnion allograft (RELIEF® treatment) performed around the shoulder fascia.
It is important to note that while amnion injections hold immense promise as a treatment option, their effectiveness may vary depending on the individual and the severity of the condition. Clinical trials assessing the use of intra-articular amnion have shown strong effectiveness (Ross et al., 2022; Gellhorn & Han, 2017); however, the RELIEF® treatment is a new approach targeting the fascia and combining hydrodissection. The long-term safety and side-effect profile of orthobiologics including amnion and other stem cell therapies are unknown since they have only been used in orthopaedics for a relatively short time. Additionally, the research that has been done often does not account for the variability in the patient diagnoses, comorbidities, and age, nor in the variability amongst preparation techniques (ie dehydrated vs cryopreserved amnion) (Johnson et al., 2016). Similar to PRP, there is also significant variability amongst studies in terms of the actual preparation, administration, and dosage of amnion allograft given. Finally, it is important to note that the overwhelming majority of orthobiologic treatments are currently not reimbursed by insurance companies, which excludes a large portion of the patient population and can significantly skew the results due to selection bias (Lattermann et al., 2022). It is also unknown how many orthobiologic injections are needed for various clinical conditions which can increase the total cost. Rigorous, larger, randomized controlled trials are needed to assess the safety, efficacy, and optimal clinical use of these newer therapies.
AC of the shoulder is defined as fibrosis and contracture of the glenohumeral joint capsule, resulting in progressive stiffness, pain, and restriction of active and passive range of motion. Despite decades of research and clinical experience, consensus on optimal treatment remains elusive. Initial management typically involves conservative approaches such as activity modification, patient education, and physical therapy to mitigate symptoms and improve function. However, these measures often prove inadequate for many patients, necessitating consideration of more advanced interventions.
Secondary treatment options include intra-articular corticosteroid (IACS) or IAHA injections, joint hydro-dissection, or surgical procedures like MUA and ACR. Recent studies challenge the traditional view of AC as a self-limiting condition, emphasizing the need for further standardization of treatment protocols and exploration of innovative therapies. Orthobiologics, have emerged as a promising new area of research and hold potential for addressing the unresolved or chronic symptoms in patients who do not respond adequately to initial conventional therapies. While these new treatment approaches do hold promise for advancing orthopedic care—ongoing rigorous research is essential to expand our understanding of their mechanisms, optimize clinical protocols, ensure safety, and establish their place in evidence-based practice. Collaborative efforts between researchers, clinicians, and regulatory bodies are crucial to realizing the full potential of these innovative therapies in improving patient outcomes.