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Frozen Shoulder

Adhesive capsulitis management: diagnostic criteria, systemic risk factors (diabetes/thyroid), and the transition from conservative therapy to hydrodilatation or manipulation.

Overview

Frozen shoulder is a painful and debilitating condition with considerable economic impact [12]. While most patients clinically diagnosed with primary frozen shoulder had undiagnosed systemic abnormalities and/or intra-articular pathologies [1], MR findings should not replace clinical judgments regarding further prognosis and treatment decisions [2]. Treatment aims to improve pain and function through a shared decision-making process [12], following a step-up approach from conservative measures to invasive treatments if symptoms persist [12].

Early surgical intervention might shorten the overall duration of symptoms in frozen shoulder and is not associated with inferior clinical outcomes when compared with late surgical intervention [5]. Different treatment strategies for frozen shoulder may be appropriate, depending on the location [6]. Arthroscopic capsular release has emerged as a suitable option for patients with refractory frozen shoulder [27], while results comparing arthroscopic release outcomes in patients with and without diabetes may be used when counselling diabetic patients for the outcome after arthroscopic treatment of frozen shoulder [63].

At 2 years after surgery, there was no significant difference in active motion between patients with and without frozen shoulder, but outcome scores remained lower in the frozen shoulder group [8]. Treatment of idiopathic frozen shoulder by manipulation under anaesthetic (MUA) led to improvement in shoulder motion and function at a mean 23 years after the procedure [28]. Patients with a poor outcome or recurrent symptoms of a frozen shoulder after MUA should be offered a further MUA with the expectation of a good outcome and a low complication rate [17].

Anatomy & Pathophysiology

Frozen shoulder is characterized by progressive pain and stiffness that typically resolves spontaneously after approximately 18 months [7]. The condition may occur without a history of prior shoulder conditions or atop any existing shoulder pathology [3]. Primary (idiopathic) frozen shoulder consists of three distinct phases: pain, stiffness, and thawing [4], whereas secondary frozen shoulders may not exhibit all three phases or follow this exact chronology [4].

Phase I (Pain): Patients experience a gradual onset of diffuse shoulder pain that is progressive over weeks to months [4]. This pain is usually worse at night and exacerbated by lying on the affected side [4, 7]. In patients aged 40–60 years, a history of trivial trauma followed by gradually increasing pain severity is often reported [7].

Phase II (Stiffness): This phase, which usually lasts 4 to 12 months, involves patients restricting movement to seek pain relief [4]. As stiffness progresses, a dull ache is present nearly all the time, especially at night [4], accompanied by sharp pain during range of motion at or near new endpoints [4]. Patients describe difficulty with activities of daily living, such as men having trouble reaching back pockets and women having trouble fastening brassieres [4]. In untreated cases, stiffness persists for another 6–12 months after pain begins to subside [7].

Phase III (Thawing): This phase lasts for weeks or months, during which motion increases and pain diminishes [4]. Without treatment other than benign neglect, motion return is gradual in most patients but may never objectively return to normal [4, 7]. Most patients subjectively feel near normal in this phase, perhaps due to compensation or adjustment in daily activities [4].

Diagnosis of primary frozen shoulder requires total elevation restricted to 135° or less [18], with motion restriction localized to the humero-scapular joint [18]. The condition is defined by the absence of findings in case history, clinical examination, or radiological examination that explain the decrease in range of motion [18]. X-rays are normal, serving primarily to exclude other causes of pain and stiffness [7]. Secondary frozen shoulder involves decreased range of motion following a traumatic lesion, including soft tissue injury, intra- and juxtaarticular fractures, and other upper limb fractures [18].

Histologically, frozen shoulder features active fibroblastic and myofibroblastic proliferation in the rotator interval, anterior capsule, and coracohumeral ligament, resembling Dupuytren's disease [7]. Conditions particularly associated with frozen shoulder include diabetes, Dupuytren's disease, hyperlipidaemia, hyperthyroidism, cardiac disease, and hemiplegia [7]. A decrease in elastogenesis and an increase in AGE may affect capsular stiffness [33]. The thickness of the inferior glenohumeral joint capsule in the 80° scapular plane elevated arm position is a highly reliable and valid assessment method [62]. Patients present with altered shoulder muscle activity and kinematics [58], though the anatomical structure of passive shoulder restraints does not impact passive joint position sense values between external and internal rotation [47].

Differentiation from other etiologies is critical. Post-traumatic stiffness is maximal at the start and gradually lessens, unlike the pattern of frozen shoulder [7]. Disuse stiffness occurs if the arm is nursed overcautiously, such as following a wrist fracture, and lacks the characteristic pain pattern of frozen shoulder [7]. Complex regional pain syndrome may follow acute trauma or be seen in patients with myocardial infarction or stroke, presenting features similar to frozen shoulder [7]. Both rheumatoid arthritis and osteoarthritis can affect the shoulder bilaterally, with diagnosis usually obvious on X-ray [7].

Regarding classification and recovery, Stage 1 (pain) of frozen shoulder according to Reeves lasts 10 to 36 weeks [18]. There is no difference in Stage 1 between men and women, affected dominant and nondominant shoulders, or with age [18]. In early stages, a full range of movement is present under anaesthesia [18]. Isolated posterior capsular contracture is the most commonly described localized contracture causing motion loss after repetitive, low-level trauma [48], with 11 of 30 patients in a refractory stiffness review showing this restriction [48]. In these cases, a partial-thickness rotator cuff tear was identified as an associated pathology in seven cases [48]. Surgical procedures such as anterior or posterior capsulorrhaphy, inferior capsular shift, and rotator cuff surgery can result in motion limitation, with patients experiencing more pronounced stiffness often having difficulty regaining normal motion after rotator cuff surgery [48].

Historical context notes that the earliest description of shoulder stiffness following trauma was recorded by Malgaigne in 1859 regarding minor nondisplaced, extracapsular fractures [48]. Malgaigne noted that elevation of the arm would always remain limited after such fractures, even after 11 to 15 months [48]. Acquired stiffness following trauma is difficult to study regarding recovery without intervention due to patient population heterogeneity [48]. Some degree of shoulder stiffness is typical after bone or soft tissue injuries around the shoulder, including simple contusions, subluxations, dislocations, acromioclavicular joint injuries, clavicle and scapula fractures, and proximal humerus fractures in the elderly [48]. After repetitive, low-level trauma, localized contractures can develop and cause motion loss in specific patterns [48]. One session of heat and manual muscle release has shown beneficial effects on shoulder muscle performance, kinematics, mobility, and pain in patients with frozen shoulder [58].

Classification

Primary Frozen Shoulder: Defined by the absence of findings in case history, clinical, or radiological examination that explain the range of motion decrease [18]. This definition excludes cases with post-traumatic conditions, rheumatoid arthritis, osteoarthritis, hemiplegia, or other obvious changes [18]. Clinically, primary frozen shoulder presents with total elevation restricted to 135° or less [18] and motion restriction localized to the humero-scapular joint [18]. Most patients clinically diagnosed with primary frozen shoulder actually have undiagnosed systemic abnormalities and/or intra-articular pathologies [1].

Secondary Frozen Shoulder: Defined as decreased range of motion following a traumatic lesion [18]. Associated injuries include soft tissue injury to the shoulder region, intra- and juxtaarticular fractures, and other fractures of the upper limb [18].

Reeves Staging: Stage 1 is characterized by pain [18] and lasts 10 to 36 weeks [18]. There is no correlation with age, gender, or affected side (dominant vs. nondominant) regarding Stage 1 [18]. In early stages, a full range of movement is present under anesthesia [18].

Other Considerations: Stiffness may arise from many causes, including frozen shoulder which can occur without history or atop any shoulder condition [3]. 18F-FDG PET/CT is clinically relevant in diagnostically challenging cases, such as distinguishing the first phase of frozen shoulder from subacromial impingement [9]. Frozen shoulder following COVID-19 vaccination may present with clinical features similar to idiopathic frozen shoulder [19]. MR findings should not replace clinical judgments regarding prognosis and treatment decisions [2]. Different treatment strategies may be appropriate depending on the location [6]. At 2 years post-surgery, active motion shows no significant difference, but outcome scores remain lower in the frozen shoulder group [8]. A consensus approach was used to obtain specialist input for proposed classifications to ensure acceptance [20]. Systematic and scoping reviews summarize the complex tissue pathophysiology and mechanisms of primary frozen shoulder [10, 15]. Decreased elastogenesis and increased AGE may affect capsular stiffness [33]. The term 'frozen shoulder' is a misnomer that should be abolished; the condition is better termed 'contracture of the shoulder' based on pathological evidence of ligament contracture rather than adhesions [34].

Clinical Presentation

The clinical presentation of frozen shoulder is defined by a well-ordered progression of pain and stiffness, typically affecting patients aged 40–60 years [7]. Primary (idiopathic) frozen shoulder presents with a gradual onset of diffuse shoulder pain that progresses over weeks to months, often following a history of trivial trauma or occurring without antecedent history [4, 7]. This pain is characteristically worse at night and exacerbated by lying on the affected side [4, 7]. Patients frequently restrict movement to seek pain relief, heralding the transition to the stiffness phase [4]. Secondary frozen shoulder follows a traumatic lesion and may not exhibit all three phases or follow the exact chronology of the primary form [4, 18]. Associated conditions include diabetes, Dupuytren's disease, hyperlipidaemia, hyperthyroidism, cardiac disease, and hemiplegia [7].

The natural history of primary frozen shoulder consists of three distinct phases: freezing, frozen, and thawing [4]. The freezing phase (Stage 1) lasts 10 to 36 weeks and is characterized by progressive pain [4, 18]. As stiffness ensues, the frozen phase typically lasts 4 to 12 months, during which a dull ache is present nearly all the time, especially at night [4]. Sharp pain often accompanies the dull ache during range of motion at or near the new endpoints [4]. Patients describe significant difficulty with activities of daily living, such as men struggling to reach back pockets and women having trouble fastening brassieres [4]. The thawing phase lasts for weeks or months; as motion increases, pain diminishes [4]. Without treatment other than benign neglect, motion return is gradual but may never objectively return to normal [4]. Most patients subjectively feel near normal after the thawing phase, likely due to compensation or adjustment in daily activities [4].

Inspection of the shoulder usually reveals nothing except slight muscle wasting [7]. Palpation may reveal some tenderness, but movements are always limited, and in severe cases, the shoulder is extremely stiff [7]. X-rays are normal in frozen shoulder; their main role is to exclude other causes of pain and stiffness [7]. Differential diagnosis must distinguish frozen shoulder from conditions that can affect the shoulder bilaterally, such as rheumatoid arthritis and osteoarthritis, which are usually obvious on X-ray [7]. Complex regional pain syndrome may follow acute trauma or occur after myocardial infarction or stroke, presenting features similar to frozen shoulder [7]. Post-traumatic stiffness may persist for months but is maximal at the start and gradually lessens, unlike the pattern of frozen shoulder [7]. If the arm is nursed overcautiously, the shoulder may stiffen, but the characteristic pain pattern of frozen shoulder is absent [7].

Diagnosis is primarily clinical, with adhesive capsulitis defined as a disorder with a natural history of gradual resolution over 1 to 3 years [14]. Primary frozen shoulder is defined by total elevation restricted to 135° or less, with motion restriction localized to the humero-scapular joint and no findings in history, clinical, or radiological examination to explain the decrease in range of motion [18]. Cases with post-traumatic conditions, rheumatoid arthritis, osteoarthritis, hemiplegia, and other obvious changes are excluded from this definition [18]. In the early stages, there is a full range of movement under an anaesthetic [18]. Persistent limitation occurs in 50% to 60% of patients with adhesive capsulitis [14]. MR findings should not replace clinical judgments regarding prognosis and treatment decisions [2]. The burning sign is an abnormal finding that appears on dynamic MRI of severe frozen shoulder [24].

Red-flag patterns and diagnostic challenges include the potential for misdiagnosing shoulder tumors as frozen shoulder syndrome, which causes significant diagnostic delay [37]. Stiffness may have many causes, including frozen shoulder which can occur without history or atop any shoulder condition [3]. The first phase of frozen shoulder can be difficult to distinguish from subacromial impingement in diagnostically challenging cases [9]. Frozen shoulder can occur after COVID-19 vaccination, presenting with clinical features similar to idiopathic frozen shoulder [19, 38]. The presence of psychological disorders such as anxiety and depression is a factor associated with the diagnosis of frozen shoulder with relative frequency and should be part of the evaluation at the time of care in the outpatient area [41]. Most patients clinically diagnosed with primary frozen shoulder had undiagnosed systemic abnormalities and/or intra-articular pathologies [1]. Early surgical intervention might shorten the overall duration of symptoms and is not associated with inferior clinical outcomes when compared with late surgical intervention [5]. Different treatment strategies may be appropriate depending on the location [6]. Histological features are reminiscent of Dupuytren's disease, with active fibroblastic and myofibroblastic proliferation in the rotator interval, anterior capsule, and coracohumeral ligament [7]. A spectrum of symptom severity exists during the freezing phase of primary adhesive capsulitis [42].

Investigations

Plain radiography: X-rays in frozen shoulder are typically normal, with their primary role being the exclusion of other causes of pain and stiffness [7]. In atraumatic shoulder pain, particularly in patients younger than 50 years, plain radiographs rarely alter the diagnosis or affect management [65]. However, physicians should re-examine patients with repeated plain radiographs and further imaging if conservative therapy fails [44]. Both rheumatoid arthritis and osteoarthritis can affect the shoulder bilaterally, with diagnoses usually obvious on X-ray [7].

MRI: Routine use of shoulder MRI scans in patients with frozen shoulder without suspicion of additional pathology may not be indicated [13]. Clinicians can refer to specific MRI features to increase confidence in diagnosing adhesive capsulitis and rule out other confused diagnoses [49]. Characteristic findings include T2 signal hyperintensity and axillary capsule thickening in early stages, though MRI alone cannot completely define the disease stage [56]. The burning sign is an abnormal finding appearing in dynamic MRI of severe frozen shoulder [24]. MRI can be useful for assessing several measures of clinical impairment in patients with adhesive capsulitis [59]. Caution is required when interpreting MRI scans soon after corticosteroid injection [56]. Post-interventional microadhesiolysis, MRI findings show reduced joint capsule thickness and effusion [73]. Following manipulation under ultrasound-guided cervical nerve root block in severe cases, MR imaging may reveal 29 capsule tears, 4 labrum tears, and 15 bone bruises of the humeral head [74]. MR findings should not replace clinical judgments regarding further prognosis and treatment decisions [2]. The accuracies for shoulder MRI in the community setting were not improved by having MRIs interpreted by selected fellowship-trained musculoskeletal radiologists [69].

CT: 18F-FDG PET/CT is clinically relevant in diagnostically challenging cases, such as distinguishing the first phase of frozen shoulder from subacromial impingement [9].

Other Considerations: Most patients clinically diagnosed with primary frozen shoulder had undiagnosed systemic abnormalities and/or intra-articular pathologies [1]. The term frozen shoulder should be reserved for a well-defined disorder characterized by progressive pain and stiffness which usually resolves spontaneously after about 18 months [7]. Histological features are reminiscent of Dupuytren's disease, with active fibroblastic and myofibroblastic proliferation in the rotator interval, anterior capsule, and coracohumeral ligament [7]. Conditions particularly associated with frozen shoulder include diabetes, Dupuytren's disease, hyperlipidaemia, hyperthyroidism, cardiac disease, and hemiplegia [7]. Mendelian randomization analysis suggests a causal relationship between hypothyroidism and frozen shoulder [72]. Patients are typically aged 40–60 years and may give a history of trauma, often trivial, followed by pain [7]. Pain gradually increases in severity, often preventing sleeping on the affected side, before subsiding after several months as stiffness becomes the primary problem [7]. Untreated stiffness persists for another 6–12 months before movement is gradually regained, though it may not return to normal [7]. Physical examination usually shows nothing except slight muscle wasting, some tenderness, and limited movements [7]. Stiffness may have many causes, including frozen shoulder which can occur without history or atop any shoulder condition [3]. Post-traumatic stiffness may persist for months after severe injury, is maximal at the start, and gradually lessens, unlike the pattern of a frozen shoulder [7]. Disuse stiffness may occur if the arm is nursed overcautiously (e.g., following a wrist fracture), and the characteristic pain pattern of a frozen shoulder is absent [7]. Complex regional pain syndrome may follow acute trauma or be seen in patients with myocardial infarction or stroke, with features similar to those of a frozen shoulder [7].

Treatment

Frozen shoulder is a well-defined disorder characterized by progressive pain and stiffness which usually resolves spontaneously after about 18 months [7]. Primary frozen shoulder consists of three phases: pain, stiffness, and thawing [4]. Phase I (Pain) involves a gradual onset of diffuse shoulder pain that is progressive over weeks to months, usually worse at night and exacerbated by lying on the affected side [4]. Phase II (Stiffness) usually lasts 4 to 12 months; patients often describe difficulty with activities of daily living, such as men having trouble reaching back pockets and women having trouble fastening brassieres [4]. In Phase II, a dull ache is present nearly all the time, especially at night, often accompanied by sharp pain during range of motion at or near new endpoints [4]. Phase III (Thawing) lasts for weeks or months [4]. Without treatment other than benign neglect, motion return is gradual in most patients but may never objectively return to normal; however, most patients subjectively feel near normal, perhaps as a result of compensation or adjustment in ways of performing activities of daily living [4]. Secondary frozen shoulders may not exhibit all three phases and may not follow the exact chronology of primary frozen shoulder; the cause for secondary frozen shoulder should be identified and treated [4].

Diagnosis and Imaging: MR findings in frozen shoulder should not replace clinical judgments regarding further prognosis and treatment decisions [2]. X-rays in frozen shoulder are normal; their main role is to exclude other causes of pain and stiffness [7]. Routine use of shoulder MRI scans in patients with frozen shoulder but without suspicion of additional pathology may not be indicated [13]. Conditions particularly associated with frozen shoulder include diabetes, Dupuytren's disease, hyperlipidaemia, hyperthyroidism, cardiac disease, and hemiplegia [7]. Patients with frozen shoulder are typically aged 40–60 years [7]. Post-traumatic stiffness is maximal at the start and gradually lessens, unlike the pattern of a frozen shoulder [7]. Disuse stiffness occurs if the arm is nursed overcautiously and lacks the characteristic pain pattern of a frozen shoulder [7]. Complex regional pain syndrome may follow acute trauma or be seen in patients with myocardial infarction or stroke, with features similar to frozen shoulder [7]. Both rheumatoid arthritis and osteoarthritis can affect the shoulder and develop bilaterally; diagnosis is usually obvious on X-ray [7]. Histological features of frozen shoulder are reminiscent of Dupuytren's disease, with active fibroblastic and myofibroblastic proliferation in the rotator interval, anterior capsule, and coracohumeral ligament [7].

Non-Operative Management: Treatment for frozen shoulder aims to improve pain and function through a shared decision-making process [12]. Treatment follows a step-up approach from conservative measures to invasive treatments if symptoms persist [12]. Conservative treatment is effective for the treatment of frozen shoulder regardless of the severity of symptoms [21]. Intra-articular steroid injection is effective and safe for frozen shoulder, relieving pain, improving functional performance, and increasing range of motion [39]. Both multisite and single glenohumeral injections of corticosteroid were effective in patients with primary frozen shoulder [40]. Management of frozen shoulder stage II to III utilizing hydrodistension and a guided exercise programme by physiotherapists in a primary care setting represents an effective non-operative treatment strategy [51]. Proprioceptive neuromuscular facilitation (PNF) can improve the shoulder joint structure of patients with frozen shoulder as an adjunctive therapy and is an effective treatment strategy [45]. A multimodal nonoperative treatment program is effective for most patients with adhesive capsulitis [61]. With supervised treatment, most patients with adhesive capsulitis will experience resolution with nonoperative measures in a relatively short period [36]. Further treatment was indicated in 41% of patients who could not tolerate more than 20 mL of injection during hydrodilatation [30]. The findings of a study on low-level laser therapy versus muscle energy technique may provide evidence on the efficacy of these interventions for diabetic patients with frozen shoulder [22].

Operative Management: Early surgical intervention might shorten the overall duration of symptoms in frozen shoulder [5]. Early surgical intervention for frozen shoulder is not associated with inferior clinical outcomes when compared with late surgical intervention [5]. Manipulation under anesthesia (MUA) in stage 2 frozen shoulder can be considered safe [16]. MUA in stage 2 frozen shoulder results in a faster recovery of range of motion compared to physiotherapy alone in the short term [16]. MUA in stage 2 frozen shoulder results in improved functional outcome compared to physiotherapy alone in the short term [16]. Treatment of idiopathic frozen shoulder by MUA led to improvement in shoulder motion and function at a mean 23 years after the procedure [28]. Arthroscopic capsular release has emerged as a suitable option for patients with refractory frozen shoulder [27]. A combination of limited capsular release and MUA for the treatment of primary frozen shoulder is a safe and effective procedure [43]. A combination of limited capsular release and MUA results in marked improvement in pain, function, and range of motion for primary frozen shoulder [43]. Different treatment strategies for frozen shoulder may be appropriate depending on the location [6]. Recurrence of frozen shoulder was more common in primary (33%) versus secondary (16%) frozen shoulder [30]. There is limited evidence of the effectiveness of different forms of treatment used for frozen shoulder [46]. Many studies evaluating treatment effects for frozen shoulder carry a moderate to high risk of bias [46]. Many studies evaluating treatment effects for frozen shoulder omit details of the duration of symptoms or the phase of the condition [46]. Frozen shoulder is a painful and debilitating condition with considerable economic impact [12].

Complications

Stiffness / Arthrofibrosis: Adhesive capsulitis is primarily a clinical diagnosis with a natural history of gradual resolution over 1 to 3 years, though persistent limitation occurs in 50% to 60% of patients [14]. Untreated stiffness persists for another 6–12 months before gradually regaining movement, which may not return to normal [7]. Most patients clinically diagnosed with primary frozen shoulder had undiagnosed systemic abnormalities and/or intra-articular pathologies [1]. Secondary frozen shoulders may not exhibit all three phases of the clinical course and may not follow the exact chronology of primary frozen shoulder [4]. As stiffness progresses in the pain phase, a dull ache is present nearly all the time, especially at night, often accompanied by sharp pain during range of motion at or near the new endpoints of motion [4]. Without treatment other than benign neglect, motion return in the thawing phase is gradual in most patients but may never objectively return to normal [4]. Most patients subjectively feel near normal in the thawing phase, perhaps as a result of compensation or adjustment in ways of performing activities of daily living [4]. In the long term, 59% of patients had normal or near normal shoulders and 41% reported some ongoing symptoms [25], and a high percentage of patients with idiopathic adhesive capsulitis present with impaired range of movement even at long-term follow-up [35].

Risk factors include an age of between 46 and 60 years [23], a previous history of contralateral frozen shoulder [23], having a sibling with frozen shoulder which may be an independent risk factor suggesting a possible genetic link [60], and diabetes, which is a likely causal risk factor likely through a pathway involving long-term high blood glucose levels [32]. At 2 years after surgery, there was no significant difference in active motion between patients with and without frozen shoulder, but outcome scores remained lower in the frozen shoulder group [8]. The term 'frozen shoulder' is a misnomer that should be abolished; the condition is better termed 'contracture of the shoulder' based on pathological evidence of ligament contracture rather than adhesions [34].

Management: MUA in stage 2 frozen shoulder results in a faster recovery of range of motion and improved functional outcome compared to physiotherapy alone in the short term [16]. All patient groups had a significantly improved range of motion and Oxford Shoulder Score in the short-term with long-term maintenance of improved Oxford Shoulder Score following manipulation under anaesthesia [26]. Patients with a poor outcome or recurrent symptoms of a frozen shoulder after a MUA should be offered a further MUA with the expectation of a good outcome and a low complication rate [17]. The long-term results of arthroscopic capsular release in frozen shoulder were confirmed in 255 patients [31].

Other Considerations: Evidence regarding systemic associations and long-term natural history indicates that while most patients subjectively feel near normal in the thawing phase, objective motion may never fully return to normal [4]. Long-term follow-up data confirms that while 59% of patients achieve normal or near normal shoulders, 41% report ongoing symptoms [25].

Recovery

The clinical course of primary frozen shoulder follows three distinct phases: Pain, Stiffness, and Thawing [4]. Secondary frozen shoulders may not exhibit all three phases or follow this exact chronology [4]. Phase I (Pain) involves a gradual, progressive onset of diffuse shoulder pain over weeks to months, typically worsening at night and when lying on the affected side [4]. Phase II (Stiffness) begins as patients restrict movement to avoid pain and lasts 4 to 12 months [4]. During this phase, patients experience difficulty with activities of daily living, such as men accessing back pockets or women fastening brassieres [4]. A dull ache is present nearly constantly, especially at night, accompanied by sharp pain at the new endpoints of motion [4]. Phase III (Thawing) lasts for weeks or months, during which motion increases and pain diminishes [4]. Without treatment other than benign neglect, motion return is gradual, though it may never objectively normalize; however, most patients subjectively feel near normal due to compensation [4]. The natural history of adhesive capsulitis involves gradual resolution over 1 to 3 years or 18–30 months, yet persistent limitation occurs in 50% to 60% of patients [14][35]. In the long term, 59% of patients achieve normal or near-normal shoulders, while 41% report ongoing symptoms [25].

Light activity (weeks): Patients typically resume desk work and light activities of daily living as pain subsides in Phase I and stiffness develops in Phase II. While specific week ranges for light activity are not explicitly quantified in the provided evidence, the transition from the progressive pain of Phase I to the stiffness of Phase II occurs over weeks to months [4].

Full activity (months): The duration for full activity and range of motion return varies based on intervention. Without treatment, motion return in Phase III is gradual over weeks or months [4]. Early surgical intervention may shorten the overall symptom duration [5]. Manipulation under anaesthesia (MUA) results in faster recovery of range of motion compared to physiotherapy alone in the short term for stage 2 frozen shoulder [16]. Arthroscopic capsular release yields greater improvements in internal rotation for patients with symptom duration <10 months compared to those with longer durations, though final results for flexion, abduction, and external rotation are similar regardless of duration [75].

Complete recovery / outcome plateau (months): Adhesive capsulitis has a natural history of resolution over 1 to 3 years [14]. At 2 years post-surgery, active motion may not differ significantly from non-frozen shoulders, but outcome scores often remain lower in the frozen shoulder group [8]. Long-term maintenance of improved Oxford Shoulder Scores is observed following manipulation under anaesthesia [26]. A high percentage of patients present with impaired range of movement even at long-term follow-up [35].

Rehabilitation protocol: With supervised treatment, most patients experience resolution with nonoperative measures in a relatively short period [36]. MUA in stage 2 frozen shoulder is considered safe [16]. Patients with poor outcomes or recurrent symptoms after an initial MUA should be offered a further MUA, which is associated with a good outcome expectation and low complication rate [17]. Early surgical intervention is not associated with inferior clinical outcomes compared to late intervention [5]. There is no reason to delay surgery for arthroscopic capsular release based on symptom duration [75].

Functional milestones: All patient groups demonstrate significantly improved range of motion and Oxford Shoulder Scores in the short term following manipulation under anaesthesia [26]. Long-term results of arthroscopic capsular release were confirmed in 255 patients [31]. Patients with a duration of symptoms <10 months made greater improvements in internal rotation following arthroscopic capsular release compared to those with longer symptom duration [75].

Other Considerations: Most patients clinically diagnosed with primary frozen shoulder have undiagnosed systemic abnormalities or intra-articular pathologies [1]. Diabetes is a likely causal risk factor, potentially via long-term high blood glucose levels [32]. An age between 46 and 60 years and a previous history of contralateral frozen shoulder are statistically significant risk factors for developing frozen shoulder after simple arthroscopic shoulder procedures [23].

Key Evidence

  • [L4] Most patients clinically diagnosed with primary frozen shoulder had undiagnosed systemic abnormalities and/or intra-articular pathologies. (10.5397/cise.2018.21.2.82)
  • [L4] MR findings in frozen shoulder should not replace clinical judgments regarding further prognosis and treatment decisions. (10.1007/s00167-015-3887-y)
  • [L5] Stiffness may have many causes, including frozen shoulder which can occur without history or atop any shoulder condition. (10.1177/1758573215569340)
  • [L3] Early surgical intervention might shorten the overall duration of symptoms in frozen shoulder and is not associated with inferior clinical outcomes when compared with late surgical intervention. (10.1016/j.jse.2020.07.023)
  • [L5] Different treatment strategies for frozen shoulder may be appropriate, depending on the location. (10.1016/j.jse.2018.03.010)
  • [L3] At 2 years after surgery, there was no significant difference in active motion, but outcome scores remained lower in the frozen shoulder group. (10.1177/2325967120934449)
  • [L2] This is clinically relevant in diagnostically challenging cases, for instance in the first phase of frozen shoulder, which can be difficult to distinguish from subacromial impingement. (10.1007/s00167-020-05937-2)
  • [L1] This systematic review presents a summary of what is currently known about the tissue pathophysiology of primary frozen shoulder. (10.1186/s12891-016-1190-9)
  • [L4] Frozen shoulder is a painful and debilitating condition with considerable economic impact; treatment aims to improve pain and function through a shared decision-making process, with a step-up approach from conservative measures to invasive treatments if symptoms persist. (10.1177/1758573215601779)
  • [L4] Therefore, routine use of shoulder MRI scans in patients with FS but without suspicion of an additional pathology may not be indicated. (10.1016/j.jseint.2022.05.009)
  • [L5] This scoping review outlines the complexity of the pathophysiology of frozen shoulder and provides a comprehensive overview of pathophysiologic mechanisms. (10.1186/s40634-020-00307-w)
  • [L1] MUA in stage 2 frozen shoulder can be considered safe and results in a faster recovery of range of motion and improved functional outcome compared to physiotherapy alone in the short term. (10.1016/j.jseint.2023.11.004)
  • [L4] Patients with a poor outcome or recurrent symptoms of a frozen shoulder after a MUA should be offered a further MUA with the expectation of a good outcome and a low complication rate. (10.1302/0301-620x.99b6.bjj-2016-1133.r1)
  • [L4] Frozen shoulder following COVID-19 vaccination may present with clinical features similar to those of idiopathic frozen shoulder. (10.1016/j.xrrt.2023.09.013)
  • [L5] However, our goal in using this consensus approach was to obtain the valuable input of shoulder specialists so that the classification proposed would be more readily accepted and used. (10.1016/j.jse.2010.07.008)
  • [L3] Conservative treatment is effective for the treatment of frozen shoulder. (10.1016/j.asmr.2025.101149)
  • [L2] The findings of the study may provide evidence on the efficacy of these interventions and most likely, the optimal treatment approach for frozen shoulder related to diabetes, which may guide clinical practice. (10.1186/s13018-024-04735-7)
  • [L3] An age of between 46 and 60 years and a previous history of contralateral frozen shoulder were statistically significant risk factors. (10.1302/0301-620x.97b7.35387)
  • [L4] The burning sign is an abnormal finding that appears in dynamic MRI of severe frozen shoulder. (10.1016/j.jse.2016.06.003)
  • [L3] In the long term, 59% of patients had normal or near normal shoulders and 41% reported some ongoing symptoms. (10.1016/j.jse.2007.05.009)
  • [L3] All patient groups had a significantly improved range of motion and Oxford Shoulder Score in the short-term with long-term maintenance of improved Oxford Shoulder Score. (10.1177/1758573214528155)
  • [L5] Randomized controlled trials are needed to support the use of either treatment modality, but for now, arthroscopic capsular release has emerged as a suitable option for patients with refractory frozen shoulder. (10.1016/j.arthro.2016.06.002)
  • [L4] Treatment of idiopathic frozen shoulder by MUA led to improvement in shoulder motion and function at a mean 23 years after the procedure. (10.1007/s11999-012-2542-x)
  • [L4] Further treatment was indicated in 41% of patients who could not tolerate more than 20 mL of injection, and recurrence was more common in primary (33%) versus secondary (16%) frozen shoulder. (10.1177/17585732221124914)
  • [L4] The long-term results of arthroscopic capsular release in frozen shoulder were confirmed in 255 patients. (10.1186/s13018-018-0758-5)
  • [L1] Diabetes is a likely causal risk factor for frozen shoulder, likely through a pathway involving long-term high blood glucose levels. (10.1371/journal.pgen.1009577)
  • [Abstract] A decrease in elastogenesis and an increase in AGE might affect capsular stiffness in frozen shoulder. (10.1016/j.jse.2015.08.015)
  • [L5] The term 'frozen shoulder' is a misnomer that should be abolished; the condition is better termed 'contracture of the shoulder' based on pathological evidence of ligament contracture rather than adhesions. (10.1111/j.1758-5740.2009.00007.x)
  • [L4] Adhesive capsulitis is a self-limiting condition with a natural history of 18–30 months, although a high percentage of patients present with impaired range of movement even at long-term follow-up. (10.1007/s00167-007-0291-2)
  • [L4] With supervised treatment, most patients with adhesive capsulitis will experience resolution with nonoperative measures in a relatively short period. (10.1016/j.jse.2006.12.007)
  • [L2] Misdiagnosing shoulder tumors as frozen shoulder syndrome is likely to cause a significant delay in making a correct diagnosis. (10.1016/j.jse.2009.05.010)
  • [L4] Frozen shoulder can occur after COVID-19 vaccination, and musculoskeletal specialists should be aware of this diagnosis to identify and treat such patients early. (10.1016/j.jseint.2022.02.013)
  • [L1] Intra-articular steroid injection is effective and safe for frozen shoulder, relieving pain, improving functional performance, and increasing range of motion. (10.1177/0363546516669944)
  • [L1] Both treatments were effective in patients with primary frozen shoulder. (10.1016/j.arthro.2021.01.069)
  • [L4] The presence of psychological disorders such as anxiety and depression are a factor associated with the diagnosis of frozen shoulder with relative frequency, and should be part of our evaluation at the time of care in the outpatient area. (10.1016/j.xrrt.2025.100623)
  • [L3] A spectrum of symptom severity exists during the freezing phase of primary adhesive capsulitis. (10.1016/j.jse.2023.01.007)
  • [L4] A combination of limited capsular release and MUA for the treatment of primary frozen shoulder is a safe and effective procedure resulting in marked improvement in pain, function and range of motion. (10.1177/1758573215578590)
  • [L4] Physicians should re-examine frozen shoulder patients with repeated plain radiographs and further imaging, especially MRI, if conservative therapy fails. (10.1016/j.jse.2011.07.026)
  • [L2] As an adjunctive therapy, PNF can improve the shoulder joint structure of patients with frozen shoulder and is an effective treatment strategy for frozen shoulder. (10.1186/s12891-022-05327-4)
  • [L2] There is limited evidence of the effectiveness of different forms of treatment used for frozen shoulder, with many studies evaluating treatment effects carrying a moderate to high risk of bias and omitting details of the duration of symptoms or the phase of the condition. (10.1111/j.1758-5740.2010.00067.x)
  • [L3] The anatomical structure of passive shoulder restraints has no impact on the difference in passive joint position sense values between external and internal rotation. (10.1186/s12891-016-0971-5)
  • [L1] Clinicians can refer to these MRI features to increase confidence in diagnosing adhesive capsulitis of the shoulder and rule out other confused diagnoses. (10.1186/s12891-025-08592-1)
  • [L4] This service evaluation demonstrates that management of frozen shoulder stage II to III, as conducted by physiotherapists in a primary care setting utilizing hydrodistension and a guided exercise programme, represents an effective non-operative treatment strategy. (10.1177/1758573217701063)
  • [Abstract] With supervised treatment, most patients with adhesive capsulitis will experience resolution with non-operative modalities in a relatively short period. (10.1016/j.jse.2007.02.028)
  • [L5] T2 signal hyperintensity and axillary capsule thickening are characteristic of the early stages of frozen shoulder, although MRI alone cannot completely define the disease stage. (10.1016/j.xrrt.2024.05.002)
  • [L4] One should use caution in the interpretation of magnetic resonance imaging scans of the shoulder soon after the injection of corticosteroids. (10.1016/j.arthro.2007.01.024)
  • [L4] Patients with frozen shoulder presented with altered shoulder muscle activity and kinematics, and one-session of heat and manual muscle release showed beneficial effects on shoulder muscle performance, kinematics, mobility, and pain. (10.1186/s12891-017-1867-8)
  • [L4] MRI can be useful for assessment of several measures of clinical impairment in patients with adhesive capsulitis. (10.1186/s12891-020-03569-8)
  • [L3] Having a sibling with frozen shoulder may be an independent risk factor, suggesting a possible genetic link. (10.1111/j.1758-5740.2011.00169.x)
  • [L3] A multimodal nonoperative treatment program is effective for most patients with adhesive capsulitis. (10.1177/0363546510385403)
  • [L3] The thickness of the inferior glenohumeral joint capsule in the 80° scapular plane elevated arm position was shown to be a highly reliable and valid method. (10.1016/j.jseint.2024.06.004)
  • [L3] These results may be used when counselling diabetic patients for the outcome after arthroscopic treatment of frozen shoulder. (10.1302/0301-620x.96b10.34476)
  • [L2] Plain radiographs rarely alter the diagnosis or affect management in the setting of atraumatic shoulder pain, particularly in patients younger than 50 years. (10.5435/jaaos-d-16-00884)
  • [L1] The accuracies for shoulder MRI in this community setting were not improved by having the MRIs interpreted by selected fellowship trained musculoskeletal radiologists. (10.1016/j.jse.2011.01.003)
  • [L2] Our MR analysis suggests that there may be a causal relationship between hypothyroidism and frozen shoulder. (10.1186/s12891-024-07826-y)
  • [L4] MRI findings showed reduced joint capsule thickness and effusion following the procedure. (10.1186/1471-2474-9-12)
  • [L4] MR imaging of patients with severe frozen shoulder after MUC showed 29 capsule tears, 4 labrum tears, and 15 bone bruises of the humeral head. (10.1016/j.jse.2015.06.019)
  • [L3] Patients with a frozen shoulder and a duration of symptoms <10 months made greater improvements in internal rotation and had similar final results for flexion, abduction, and external rotation following arthroscopic capsular release when compared with patients who had a longer duration of symptoms, so there is no reason to delay surgery. (10.1177/2325967119867621)

See Also

References

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