Factors associated with treatment success following shoulder intra-articular steroid injections

Merve Sekizkardes Tutuncu; Yusuf Oguzhan Yuruk; Medine Yılmaz; Zehra Nur Yüce; Binnur Ercan; Buse Nur Aksoy; Abdelrhman Sallam; Savas Sencan

doi:10.5606/agri.2026.105

Merve Sekizkardes Tutuncu^¹, Yusuf Oguzhan Yuruk^², Medine Yılmaz^³, Zehra Nur Yüce^³, Binnur Ercan^³, Buse Nur Aksoy^³, Abdelrhman Sallam^³, Savas Sencan^¹

¹Department of Physical Medicine and Rehabilitation, Division of Pain Medicine, Marmara University Faculty of Medicine, İstanbul, Türkiye
²Department of Physical Medicine and Rehabilitation, Marmara University Faculty of Medicine, Istanbul, Türkiye
³Marmara University Faculty of Medicine, İstanbul, Türkiye

Keywords: Adhesive capsulitis, injection, shoulder, steroid, treatment success.

Abstract

Background: This study aims to investigate the factors which influence the treatment efficacy of intra-articular corticosteroid injections in patients with adhesive capsulitis.

Patients and Methods: Between January 2020 and January 2024, a total of 126 patients who received intra-articular steroid injections for adhesive capsulitis were retrospectively analyzed. Pain severity was measured using the Numerical Rating Scale (NRS-11) at four time points: pre-procedure, 1 h post-procedure, three weeks, and three months. Treatment success was defined as a ≥ 50% reduction in the NRS-11 pain scores at three months compared to baseline. Based on this criterion, the patients were categorized into two groups: responders and non-responders. The Central Sensitization Inventory (CSI) was used to evaluate central sensitization and Charlson Comorbidity Index (CCI) was used to assess comorbidity scores. Both groups were compared in terms of demographics, baseline pain scores, range of motion, and magnetic resonance imaging findings.

Results: Of the patients, 40 were male and 86 were female with a mean age of 60.8 ± 11.02 (range, 32 to 83) years. A reduction of ≥ 50% in NRS-11 pain scores was observed in 95.2%, 69.8%, and 67.5% of patients at 1 h, three weeks, and three months post-injection, respectively. There were no significant differences between responders and non-responders in terms of demographic characteristics, baseline pain scores and range of motion, CSI scores, or CCI scores. However, on both univariate and multivariate logistic regression, the presence of acromioclavicular joint degeneration was independently associated with lower odds of treatment success (adjusted odds ratio [OR] = 0.34, 95% confidence interval [CI]: 0.13-0.90, p = 0.030).

Conclusion: Intra-articular corticosteroid injections do not consistently yield favorable outcomes in patients with adhesive capsulitis. Neither central sensitization nor composite comorbidity scores appear to be reliable predictors of treatment failure. However, the presence of additional degenerative changes, such as acromioclavicular joint degeneration, may be associated with poorer outcomes.

Introduction

Adhesive capsulitis, commonly referred to as frozen shoulder, is a frequent clinical condition characterized by contracture of the glenohumeral capsule. Its prevalence in the general population is estimated at 2 to 5%.[1] The disorder typically occurs after the age of 40 and is often associated with comorbidities such as diabetes mellitus, thyroid dysfunction, and dyslipidemia.[2]

The diagnosis of adhesive capsulitis is primarily clinical, typically presenting with shoulder pain and restricted range of motion (ROM). Although often considered a self-limiting condition, it can be refractory to treatment. Initial management generally involves physical therapy, an exercise regimen, and non-steroidal anti-inflammatory drugs (NSAIDs). However, in cases unresponsive to conservative therapy, minimally invasive interventions such as intra-articular corticosteroid injections may be necessary.[3-5]

Intra-articular corticosteroid injections have been reported to offer significant pain relief and functional improvement in adhesive capsulitis.[6,7] However, not all patients respond favorably to these interventions.[8,9] To illustrate, the presence of diabetes has been associated with reduced treatment efficacy, potentially due to connective tissue proliferation and thickening, which may lead to decreased ROM.[8] Additionally, higher pre-injection pain scores and limited improvement in ROM following injection have been identified as predictors of treatment failure.[9] Shoulder pain that is unresponsive to injections or surgical interventions is attributed not only to structural abnormalities, but also to psychological factors such as depression and anxiety, social and emotional factors.[10] Moreover, central sensitization (CS), defined as increased responsiveness of nociceptive neurons in the central nervous system, has been implicated in chronic, treatment-resistant shoulder pain.[11,12] Altered pain perception due to changes in pain threshold has been shown to reduce the therapeutic effectiveness of subacromial corticosteroid injections in chronic shoulder impingement syndrome; however, its impact on adhesive capsulitis has not been investigated yet.[13] A Cochrane review suggested that intra-articular injections could provide benefit for patients with adhesive capsulitis; however, the available evidence is insufficient to draw firm conclusions.[14] Another Cochrane review reported that intra-articular corticosteroid injections were more effective than a combination of manual therapy and exercise in the short term.[15] Both reviews emphasize the need for more comprehensive research to identify factors that influence treatment success or failure across different modalities.

In the present study, we hypothesized that higher levels of CS and a greater comorbidity burden could be associated with poorer responses. We, therefore, aimed to identify variables influencing the efficacy of intra-articular corticosteroid injections in adhesive capsulitis and to investigate the potential relationship between specific magnetic resonance imaging (MRI) findings and treatment success.

Materials and Methods

This single-center, retrospective clinical study was conducted at Marmara University Faculty of Medicine, Department of Physical Medicine and Rehabilitation, Division of Pain Medicine between January 2020 and January 2024. Initially, medical records of patients who were diagnosed with adhesive capsulitis and underwent intra-articular corticosteroid injection under either fluoroscopic or ultrasonographic guidance were screened. Adhesive capsulitis was diagnosed based on limitation in both active and passive shoulder ROM involving abduction, flexion, extension, or internal/external rotation, accompanied by pain that interferes with activities of daily living.[16,17] Structural causes, including dislocations, subluxations, prior surgery, and fractures in the shoulder region, were excluded. Inclusion criteria were as follows: having a diagnosis of adhesive capsulitis according to the aforementioned criteria, age ≥ 18 years, and pre-procedural pain score ≥ 4 on the 11-point Numerical Rating Scale (NRS-11). Exclusion criteria were as follows: structural abnormalities of the shoulder, recent dislocations or subluxations, prior shoulder surgery or fractures, active infection, active inflammatory disease, or malignancy, missing or incomplete clinical/radiographic records, and lack of access to relevant imaging data. A total of 401 patients initially met the eligibility criteria. The patients were further excluded if they received more than one injection, had incomplete datasets, or could not be contacted for follow-up questionnaires. Finally, a total of 126 patients were included in the final analysis (Figure 1). The study protocol was approved by the Marmara University Faculty of Medicine Clinical Research Ethics Committee (Date: 12.01.2024, No: 09.2024.84). The study was conducted in accordance with the principles of the Declaration of Helsinki.

Figure 1. Study flowchart. CSI, central sensitization inventory; CCI, Charlson Comorbidity Index; MRI, magnetic resonance imaging.

All patients had a prior clinical diagnosis of adhesive capsulitis and underwent a standardized intra-articular injection protocol consisting of 6 mg betamethasone, 10 mg bupivacaine hydrochloride, and 1 mL saline.

Demographic data such as age, sex, and body mass index (BMI) were retrieved from hospital records. Relevant clinical data, including symptom duration, physical examination findings, and MRI results, were also obtained from electronic hospital records. Comorbidities, such as diabetes, thyroid dysfunction, and cardiovascular diseases, were identified through outpatient and primary care physician notes.

Range of motion was assessed in abduction, flexion, and external rotation using a goniometer. The ROM limitations were categorized based on criteria similar to those proposed by Hanish et al.,[9] but adapted to reflect the system routinely used in our clinical practice. Specifically, for abduction and external rotation, a range of ≥ 45° was considered mild limitation, whereas < 45° was considered severe limitation. For flexion, a range of ≥ 120° was classified as mild, and < 120° as severe limitation. The type of procedural guidance, fluoroscopy or ultrasonography, was also documented.

Central sensitization was evaluated using the Central Sensitization Inventory (CSI), a tool for screening patients with chronic pain, including a validated Turkish language version.[18] The CSI comprises two parts: Part A includes 25 somatic and psychosocial symptoms commonly associated with CS, scored from 0 to 100. Part B, which is not scored, assesses the presence of comorbid conditions strongly linked to CS. A score of ≥ 40 was considered indicative of CS. Following retrospective record review, eligible patients were contacted via telephone, and CSI assessment was completed after obtaining informed consent.

Comorbidity burden was assessed using the Charlson Comorbidity Index (CCI), which accounts for 19 medical conditions, each assigned a weight (1-6) based on severity. The total CCI score was calculated by summing the individual condition scores and adding one point for each decade of life beyond age 40.[19] This score reflects overall comorbidity risk. Patients were contacted via telephone for CCI assessment following informed consent.

Pain severity was measured using the NRS-11 at four time points: Pre-procedure, 1 h post-procedure, three weeks, and three months. A reduction of ≥ 50% in the NRS-11 score at three months compared to baseline was defined as a successful treatment outcome.[20] Patients were accordingly categorized as responders or non-responders, and the two groups were compared across all recorded variables.

Statistical analysis

Statistical analysis was performed using the IBM SPSS version 20.0 software (IBM Corp., Armonk, NY, USA). The Shapiro-Wilk test assessed normality for continuous data. Continuous data were presented in mean ± standard deviation (SD) or median (min-max), while categorical data were presented in number and frequency. The chi-square test was used to compare categorical variables. The Mann-Whitney U test was used for non-normally distributed variables, whereas the independent samples t-test was used for normally distributed variables. Temporal changes were analyzed using repeated measures analysis of variance (ANOVA). To evaluate associations between individual variables and MRI findings and three-month treatment outcome, univariate binary logistic regression was performed for each variable, with treatment success as the dependent variable; the results are reported as odds ratios (ORs) with 95% confidence intervals (CIs). A multivariate logistic regression model was additionally constructed including all MRI findings with an adequate number of events to identify findings independently associated with treatment success while accounting for the coexistence of multiple imaging findings within the same patient; findings present in fewer than 10 patients were excluded from the multivariate model due to an insufficient events-per-variable ratio. A two-tailed p value of < 0.05 was considered statistically significant.

Results

Of a total of 126 patients included in the study, 40 were male and 86 were female with a mean age of 60.8 ± 11.02 (range, 32 to 83) years. The majority of patients (62.6%) had CS. Intra-articular steroid injections were administered under fluoroscopic guidance in 39.7% of patients and under ultrasonographic guidance in 60.3% of patients. Demographic and clinical characteristics of the patients are presented in Table 1.

Table 1. Demographic and clinical characteristics of the patients

A reduction of 50% or more in the NRS-11 pain score following intra-articular shoulder injection was considered a clinically significant improvement. This improvement was observed in 95.2%, 69.8%, and 67.5% of patients at 1 h, three weeks, and three months post-procedure, respectively (Table 1).

Pairwise comparisons of NRS-11 scores across the four assessed time points, using repeated-measures ANOVA with Bonferroni post-hoc correction, are presented in Table 2. Compared to pre-procedural NRS-11 scores, the NRS-11 scores at 1 h, three weeks, and three months after intra-articular shoulder injection were significantly lower (p < 0.001 for all). Except for the comparison between the three-week and three-month follow-ups (p = 1.000), all other time point comparisons demonstrated statistically significant differences in NRS-11 scores (p < 0.001 for all).

Table 2. Changes in NRS scores throughout the treatment period

The patients were divided into two groups based on treatment outcomes at three months following intra-articular shoulder injection: 85 patients (67%) achieved successful treatment (responder group), while 41 patients (33%) did not (non-responder group). The two treatment groups did not differ significantly in their baseline demographic or clinical characteristics, and this similarity was also supported by univariate logistic regression analysis (Table 3).

Table 3. Comparison of demographic and clinical characteristics according to 3-month treatment outcome

Non-responders exhibited a significantly higher incidence of acromioclavicular (AC) joint degeneration compared to responders (OR = 0.38, 95% CI: 0.15-0.95, p = 0.039). No other MRI finding differed significantly between the groups in the univariate analysis (Table 4). In the multivariate logistic regression including all MRI findings present in at least 10 patients, to account for the coexistence of multiple imaging findings within the same patient, AC degeneration remained the only finding independently associated with treatment success (adjusted OR = 0.34, 95% CI: 0.13-0.90, p = 0.030) (Table 5).

Table 4. Comparison of shoulder MRI findings according to 3-month treatment outcome

Table 5. Multivariate logistic regression of MRI findings independently associated with treatment success

Discussion

In the present study, we aimed to variables which influenced the efficacy of intra-articular corticosteroid injections in adhesive capsulitis and investigated the potential relationship between specific MRI findings and treatment success. Our study results showed that, although a statistically significant improvement was observed at each time point; a 50% reduction in pre-procedural NRS-11 scores was not consistently achieved. Contrary to our hypothesis, the rates of CS and comorbidities did not significantly differ between the responders and non-responders. Additionally, pre-procedural NRS-11 scores and limitations in ROM were not significantly different between the two groups. More intriguingly, the presence of AC joint degeneration on MRI was more frequently observed in non-responders. These findings suggest that AC joint degeneration may be associated with treatment response in patients with adhesive capsulitis. Specifically, its higher prevalence among non-responders may indicate a potential relationship between concomitant AC joint pathology and the likelihood of achieving a clinically meaningful response to intra-articular corticosteroid injection.

Intra-articular corticosteroid injections are recognized as an effective intervention for reducing pain and improving function in adhesive capsulitis.[3,7,21] However, some patients do not respond as favorably.[9] Few studies have investigated the factors associated with suboptimal treatment outcomes.[22] To the best of our knowledge, this is the first study to examine the association between CSI scores and CCI and treatment outcomes in this patient population. In our study, significant improvements in clinical outcomes were observed following intra-articular corticosteroid injection; however, treatment response varied among patients. Further studies are warranted to validate this association and to clarify the clinical significance of AC joint degeneration in predicting treatment response to intra-articular corticosteroid injections in patients with adhesive capsulitis.

Patients who have CS exhibit altered pain processing mechanisms, such as increased response of the central nervous system to sensory input, which may contribute to or worsen the clinical presentation of various musculoskeletal pathologies.[23-26] Enhanced neural activity, combined with impaired inhibitory pathways and overactive facilitatory mechanisms, results in abnormal sensory processing and increased pain sensitivity. A sensitized central nervous system amplifies pain perception, often beyond what would be expected based on the extent of tissue damage, making symptom severity disproportionate to clinical or imaging findings.[27-29] In our study, the prevalence of CS was 62.6%, a notably high rate. Previous reports in the general population have reported a prevalence ranging from 4.2 to 24.8%, with higher rates consistently observed among women.[30,31] Higher prevalence has also been documented in certain medical conditions; to illustrate, 44.9% in rheumatic diseases, 52.4% in post-polio syndrome, and 39.4% in rotator cuff tears.[32-34] Notably, the relationship between CS and adhesive capsulitis specifically has received limited direct study, with existing literature acknowledging this as an unresolved question.[35] Several factors may explain the comparatively high prevalence in our cohort. First, patients were recruited from a tertiary referral pain clinic, where more severe or chronic cases are typically seen, increasing the likelihood of CS. Second, the majority of participants were female (68.3%), consistent with prior evidence linking female sex to higher prevalence rates. Finally, the CSI was administered via telephone at the time of the study and assessed retrospectively rather than at the time of injection, a design feature that may have introduced potential sources of bias.

Although several previous studies have reported that CS negatively impacts post-treatment outcomes, our study found no significant difference in CS scores between the two groups.[13] There are several potential reasons for this discrepancy. First, we employed the CSI, a validated and widely used tool favored for its ease of use and cost-effectiveness. CSI offers information on different aspects of pain sensitization and has been shown to predict treatment response in several patient groups.[24,36] Moreover, it also correlates psychological and functional parameters such as disability which are important in treatment outcomes.[37] However, other assessment methods, such as QST, which measures mechanical, thermal, or pressure pain thresholds, or functional MRI, exist and can provide objective data.[26] These methods, however, are rarely feasible in clinical practice due to their time-consuming nature.[11] Schiff and Eisenberg[38] utilized QST and demonstrated that pre-procedural QST scores could predict the success of lumbar epidural steroid injections. Coronado and George,[39] on the other hand, reported that exclusive reliance on the CSI shows only a weak correlation with QST and is inadequate for identifying widespread pain. Thus, despite not being the gold standard and its time-consuming nature, pressure pain threshold testing within QST could have offered more valuable data in our study. Our use of a validated yet inherently subjective tool like the CSI may thus explain the absence of a significant difference between the two groups. Furthermore, in our study, CSI scores were obtained retrospectively, and those scores were compared with treatment outcomes from an earlier timepoint, which could introduce confounding variables. It is also plausible that the impact of CS on treatment outcomes varies depending on the specific condition. For instance, although a negative correlation between CS and treatment response has been demonstrated in subacromial impingement syndrome, such a relationship may not apply to adhesive capsulitis.[13] As a more chronic condition characterized by distinct clinical stages—painful, ROM-limiting (freezing), frozen, and thawing phases—the effect of CS in adhesive capsulitis may differ according to the disease stage.[40] However, our sample did not include a homogeneous distribution of patients across these stages, which may have influenced the findings.

Contrary to our hypothesis, responders and non-responders did not differ significantly in terms of CCI scores. It is well-established that obese individuals, as well as those with diabetes and thyroid dysfunction, are at increased risk for developing adhesive capsulitis.[41] Moreover, previous studies have demonstrated that patients with diabetes tend to respond less favorably to intra-articular corticosteroid injections compared to non-diabetic individuals.[42,43] Given these known associations, and observing no such patterns in our preliminary results, we used the CCI, a more comprehensive screening tool encompassing 19 conditions, with higher scores indicating greater comorbidity burden.[19] This approach was intended to identify potential trends related to other comorbidities that could be more thoroughly explored in future studies. However, in our study, higher CCI scores did not correlate with poorer treatment outcomes. While some studies have reported that a higher comorbidity burden negatively affects general health and functional outcomes following spine surgery, Jenkins et al.[44] found that, contrary to their hypothesis, the CCI was not a reliable predictor of outcomes after spinal fusion.[44,45] In relation to cardiovascular conditions, Kingston et al.[41] reported that patients with hypertension were actually less likely to develop adhesive capsulitis. These findings suggest that a higher overall comorbidity burden may not necessarily predict poor treatment response. Future studies may benefit from examining the influence of specific medical conditions individually, rather than composite scores, on the efficacy of intra-articular corticosteroid injections in adhesive capsulitis.

Although the mean symptom duration and pre-procedural NRS-11 scores were higher in non-responders, these differences did not reach statistical significance. Hanish et al.[9] reported that elevated baseline pain scores and greater ROM limitations, particularly in external rotation, were associated with treatment failure. In our study, we observed similar trends, with non-responders showing higher pre-procedural pain scores and more pronounced external rotation restriction; however, these findings may not have achieved statistical significance due to our limited sample size.

Finally, in terms of MRI findings, the only statistically significant difference between the two groups was a higher prevalence of AC joint degeneration among non-responders compared to responders. Although bursitis was also more frequent in non-responders, this difference did not reach statistical significance. One possible explanation is that existing but untreated AC joint degeneration may have been masked by the dominant clinical presentation of adhesive capsulitis. As a result, following intra-articular injection, residual pain may have been more attributable to the underlying AC joint pathology. Another possibility is that joint degeneration itself contributes to increased local inflammation, which may enhance pain through mechanisms of peripheral sensitization, thereby reducing the effectiveness of pain relief in that region.[46]

While this study offers a novel contribution by being the first to investigate the relationship between CSI scores, CCI, and treatment outcomes in adhesive capsulitis, several limitations should be acknowledged. First, the final sample size was smaller than anticipated due to incomplete datasets and difficulties in contacting some patients. Second, follow-up adherence was suboptimal; many participants missed their scheduled three-week and three-month clinical visits, requiring outcome assessment via telephone interviews, which may have introduced reporting bias. Third, shoulder MRI pathologies were determined based on existing radiology reports rather than a single standardized re-evaluation, which may represent a source of bias. Finally, inherent limitations of the retrospective design, such as reliance on retrospective CS assessment and incomplete access to patients’ full medication lists, may have affected the consistency of the data. Future prospective studies with standardized follow-up protocols are needed to address these limitations.

In conclusion, intra-articular corticosteroid injections do not consistently yield favorable outcomes in patients with adhesive capsulitis. Based on our findings, neither CS nor composite comorbidity scores appear to be reliable predictors of treatment failure. However, the presence of additional degenerative changes, such as AC joint degeneration, may be associated with poorer outcomes. Future multi-center, large-scale, prospective studies are needed to confirm these findings and establish more definitive conclusions.

Cite this article as: Sekizkardes Tutuncu M, Yuruk YO, Yılmaz M, Yüce ZN, Ercan B, Aksoy BN, et al. Factors associated with treatment success following shoulder intra-articular steroid injections. Agri 2026;38(4):247-256. doi: 10.5606/agri.2026.105.

Author Contributions

M.S.T.: Investigation, data curation, formal analysis, writing-original draft, writing-review & editing; Y.O.Y.: Methodology, investigation, data curation, formal analysis, supervision; M.Y., Z.N.Y.: Conceptualization, methodology, investigation, data curation; B.E.: Methodology, investigation, data curation, formal analysis, writing-original draft; B.N.A.: Conceptualization, methodology, data curation, formal analysis; A.S.: Methodology, data curation, formal analysis; S.S.: Conceptualization, methodology, writing , supervision, project administration.

Conflict of Interest

The authors declared no conflicts of interest with respect to the authorship and/or publication of this article.

Use for AI for Writing Assistance

The authors declare that artificial intelligence (AI) tools were not used, or were used solely for language editing, and had no role in data analysis, interpretation, or the formulation of conclusions. All scientific content, data interpretation, and conclusions are the sole responsibility of the authors. The authors further confirm that AI tools were not used to generate, fabricate, or ‘hallucinate’ references, and that all references have been carefully verified for accuracy.

Financial Disclosure

The authors received no financial support for the research and/or authorship of this article.

Data Sharing Statement
The data that support the findings of this study are available from the corresponding author upon reasonable request.

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