Effects of Scapular Interventions on Pain and Disability in Subjects with Neck Pain: A Systematic Review and Meta-analysis of Randomized Controlled Trials

Abstract

Background

Musculoskeletal neck pain is the fourth common cause of disability worldwide. Scapula dysfunction can subsequently lead to neck pain. Previous literature could not establish the effectiveness of scapular stabilization exercises on neck pain due to the different definitions used for exercise in different studies. There is a need for quality evidence examining the effectiveness of scapular interventions on pain and disability in patients with neck pain.

Data Sources

PubMed, EMBASE, Scopus, Cochrane, OVID, and PEDro were searched from 1 April 2011 to 31 March 2022.

Methods

We included randomized controlled trials that focused on scapular interventions and other active strategies in the management of neck pain. The following outcomes were assessed: pain, disability, and quality of life. PEDro scale was used to assess the risk of bias and the data pooled was analyzed using standardized mean difference.

Results

The 5 trials included in the review assessed (116 participants) the effects of scapular interventions in patients with chronic nonspecific neck pain. Risk of bias for one study was low and that for the others was moderate. The meta-analysis showed that there was a significant difference between the combined effect of neck and scapula interventions and only neck interventions group (Standardized mean difference −1.51, 95% CI [−2.79, −0.23], z=2.32, p=0.02). On assessing the effect of scapula interventions on disability, the results revealed that there was no significant (p=0.40) impact.

Conclusion

Moderate quality evidence was found for the combined effect of scapular and neck interventions in reducing pain in patients with neck pain. However, it was not effective in improving the disability.

Introduction

Musculoskeletal neck pain is the fourth common cause of disability worldwide¹⁾. The prevalence of neck pain ranges from 16.1% to 75.1%²⁾. Among the various causes of neck pain, one potential contributor may be scapula dysfunction. Scapula dysfunction is a collective term that refers to the abnormal position of scapula during static and dynamic postures³⁾. It often occurs as a result of altered muscle function of the scapulothoracic muscles⁴⁾, and alterations in muscle function can subsequently lead to neck pain⁵⁾. Alterations in scapulothoracic muscle function can potentially result in mechanical strain to the cervical structures as the scapula and cervical spine share common muscle attachments⁶⁾. It is evident that muscular dysfunction can cause alteration in scapular kinematics; however, this cannot be considered as the only factor since the lack of soft tissue flexibility may also be responsible for the restricted movements of the scapula⁷⁾. This suggests that the interaction between the scapula and neck pain should be considered during the rehabilitation process.

Rehabilitation of the scapular muscles has gained attention in recent years^8-11) focusing on the effect of scapular strengthening exercises on neck pain. Studies have explored the effects of scapular strengthening exercises by examining various treatment approaches including individual strengthening of scapular muscles⁹⁾, scapular function training¹¹⁾, global postural re-education¹²⁾, active and passive postural correction strategies^13,14), movement impairment-based treatment¹⁵⁾, scapular strengthening exercise¹⁰⁾, and use of other adjunct therapies such as cognitive behavioral therapy in individuals with neck pain¹⁶⁾. Current evidence on treatment directed at scapular structures suggest that scapular rehabilitation plays an important role in the management of neck pain. However, conclusive evidence is not available to guide clinicians as to which scapular interventions are most optimal for the management of neck pain. A recent systematic review¹⁷⁾ investigated the effectiveness of scapular stabilization exercises on managing nonspecific chronic neck pain and concluded that the data from the studies were not sufficient to establish the effect of scapular stabilization exercises. Moreover, the review could not measure consistent variables including pain scale, dysfunction, and quality of life.

Since previous literature could not establish the effectiveness of scapular stabilization exercises on neck pain due to the different definitions used for exercise in different studies, there is a need for quality evidence examining the effectiveness of scapular interventions on pain and disability in patients with neck pain. There is also a need for meta-analysis on the effectiveness of scapular interventions on neck pain. Therefore, this systematic review and meta-analysis aim to evaluate the effects of scapular interventions in subjects with mechanical neck pain.

Materials and Methods

This systematic review and meta-analysis were performed to identify the effect of scapular interventions on pain and disability in subjects with neck pain. This review was reported according to PRISMA guidelines. This review is registered in PROSPERO with a registration number CRD42021274550.

Identification and selection of studies

A comprehensive search was performed for randomized controlled trials conducted from 1 April 2011 to 31 March 2022 on the following databases: PubMed, EMBASE, Scopus, Cochrane, OVID, and PEDro. In addition to the database search, a manual search was performed to identify randomized controlled trials from the reference lists of relevant reviews and citation tracking of included RCTs. Randomized controlled trials that focused on scapular interventions and other active strategies in the management of neck pain were included. Case reports and reviews were excluded. Studies that have included shoulder pathologies and other neck pain pathologies including cervical radiculopathy and cervicogenic headache were also excluded.

Two independent authors NP and KH reviewed the studies identified by the search and extracted articles that met the inclusion criteria. The titles of all articles were reviewed first. Disagreement between two authors was resolved by discussion. In case in which an agreement could not be reached, an additional author JC reviewed the title to determine whether it should be included. The same procedure was used to review the abstracts and full texts. Two reviewers NP and KH rated all articles for risk of bias using the PEDro scale.

Assessment of characteristics of studies

Risk of bias

The PEDro scale and Cochrane risk of bias tool were used to assess the risk of bias. Two experienced raters scored each study. The total score was based on the total number of yes responses. The score of 0 was considered as high risk and 10 as low risk.

Participants

Randomized controlled trials that assessed the combined effect of scapular interventions and neck exercises or isolated scapular interventions on subjects' neck pain.

Intervention

Studies focused on combined neck and scapular interventions or isolated scapular interventions and other active strategies in the management of neck pain. Experimental group which focused on neck strengthening exercises, manipulation, mobilization, and taping.

Outcome measures

To be included in the review, the trials had to report either pain or disability or quality of life as an outcome.

Data extraction and analysis

Data was extracted by two independent reviewers NP and KH using a standardized data extraction sheet. In case of any discrepancies, the third author JC was consulted for resolving the issues. The extracted data included the characteristics of the trial and outcome data. Raw outcome data of both control and experimental groups was also extracted. Attempts were made to contact corresponding authors to collect relevant information if additional data was required.

RevMan 5.3 software was used to calculate the standardized mean difference. Standardized mean difference (SMDs) at 95% CI calculated for continuous outcomes was obtained from extracted means and standard deviations recorded at various time points. Treatment effect size was calculated using effect size calculator for t-test¹⁸⁾. The overall effect size was classified as small (0.2), medium (0.5), and large (0.8). Higgins I² statistic was used to assess the heterogeneity among the studies. A value of 25%, 50%, and 75% was considered moderate, substantial, and considerable heterogeneity, respectively. The level of evidence was determined according to Cochrane collaboration recommendation as strong, moderate, limited, conflicting, or none¹⁹⁾.

Results

Flow of studies through review

The search was conducted on PubMed, Scopus, Embase, PEDro, OVID, and Cochrane library. The search strategy yielded 3781 articles on the initial search. A total of 1834 duplicates were excluded yielding a total number of 1947 of articles for the title review. A total of 1932 articles were excluded on title screening and 15 full text articles were included for screening. Ten articles were excluded based on the inclusion and exclusion criteria. Five articles were included for qualitative and quantitative analysis. The flow diagram of the review process is provided in Fig. 1.

Figure 1.

Flow diagram of the review process.

Characteristics of studies

Risk of bias

Risk of bias for five studies was scored by two independent raters. The mean PEDro score was 6.14±1.06. The PEDro scoring for individual trials and the total score are provided in Table 1. Risk of bias assessment done using Cochrane risk of bias tool showed Allocation concealment, blinding of outcome assessment had a higher risk of bias followed by blinding of participants. Fig. 2 shows the Cochrane risk of bias assessment graph. Fig. 3 shows risk of bias summary about each risk of bias item for each included study.

Table 1.

PEDro Score of Included Studies.

Study	Eligibility Criteria	Random Allocation	Concealed Allocation	Baseline Comparability	Blind Subjects	Blind Therapist	Blind Assessors	Adequate Follow up	Intention to Treat Analysis	Between Group comparisons	Point Estimates and Variability	Total Score
Alshami et al (2021) 22)	Yes	Yes	No	Yes	Yes	No	No	Yes	No	Yes	Yes	6
Fatima et al (2021) 21)	Yes	Yes	No	Yes	No	No	No	Yes	No	Yes	Yes	5
Javdaneh et al (2020) 23)	Yes	Yes	Yes	Yes	No	No	Yes	Yes	Yes	Yes	Yes	8
Javdaneh et al (2021) 24)	Yes	Yes	Yes	Yes	No	No	Yes	Yes	No	Yes	Yes	7
Yildiz et al (2018) 8)	Yes	Yes	No	Yes	No	No	Yes	Yes	No	Yes	Yes	6

Figure 2.

Risk of bias graph.

Figure 3.

Risk of bias summary for each included study.

Participants

The 5 trials included in the review assessed (96 participants) the effects of scapular interventions in patients with chronic nonspecific neck pain. Table 2 shows the characteristics of the included studies.

Table 2.

Characteristics of the Included Studies.

Author and Year	Participants	Outcomes	Experimental Group	Control Group	Intervention Details	Follow-up
Alshami et al (2021) 22)	n=40	Pain, Cervical range of motion, Pressure pain threshold, scapular Range of motion, Neck disability index	Movement with Mobilization+ Neck and scapulothoracic exercises+taping	Neck and scapulothoracic exercises+taping	Frequency: 2-3 days/3 weeks Intensity: 10 reps with 10 secs hold Time: 30-60 minutes Type: Movement with Mobilization+Scapulothoracic strengthening exercise	3rd and 6th week
Fatima et al (2021) 21)	n=28	Pain, Disability, Sleep quality, Quality of life, scapular muscle strength, proprioception	Scapular stabilization and upper limb proprioceptive exercises+cervical stabilization exercises	Cervical stabilization exercises	Frequency: 3 sessions/week for 4 weeks Intensity: 8-12 reps Time: Not mentioned Type: Strengthening exercise	4 weeks
Javdaneh et al (2020) 23)	n=48	Pain, Kinesiophobia, Muscle activity	Scapular exercises	Home exercises	Frequency: 3 days/week for 6 weeks Intensity: 3 sets of 10-15 reps Time: 40-60 minutes Type: Strengthening exercises	6 weeks
Javdaneh et al (2021) 24)	n=48	Pain, Kinesiophobia, Disability	Neck and Scapular strengthening exercise	Neck strengthening exercise	Frequency: 3 days/week for 6 weeks Intensity: Not mentioned Time: 40-60 minutes Type: Strengthening exercise	6 weeks
Yildiz et al (2018) 8)	n=30	Pain, Disability, Scapular kinematics	Neck focused and Scapular stabilization training	Neck focused training	Frequency: Once a day for 6 weeks Intensity: 3 sets of 10 reps Time: Not mentioned Type: Strengthening exercise	6 weeks

Intervention

Each study used different scapular interventions. The studies used the following interventions: scapula-focused interventions⁸⁾, scapula training exercises^16,20), upper limb proprioception exercises²¹⁾, and scapulothoracic mobilization²²⁾. The interventions commonly targeted strengthening of muscles around the scapula and thoracic spine. Table 2 shows the details of exercise prescription utilized in each study including frequency, intensity, time, and type of exercise provided in the experimental and control groups.

Table 3 reports the level of evidence of scapular interventions on pain and disability against the comparator groups for patients with mechanical neck pain.

Table 3.

Quality of Evidence for Scapular Interventions against Control Group for Neck Pain.

Strength of Evidence	Against Neck Strengthening and Stabilization Exercises	Against Home Exercises
Strong	-	-
Moderate	Scapular exercises significantly improve pain and disability	Scapular exercises significantly improve pain
Limited	-	-
No evidence	-	-

Clinical outcomes

Pain scale

Four of five studies^8,21-24) used Visual Analog Scale and one study²¹⁾ used NPRS. Table 4 shows the summary of pain scores with scapular interventions. All the studies showed significant improvement in pain in both groups.

Table 4.

Summary Results of Pain Score with Scapular Interventions.

Author and Year	Pain Scale Used	Pain Score Preintervention	Pain Score Postintervention	Pain Score Precontrol	Pain Score Postcontrol
Alshami et al (2021) 22)	Visual Analogue Scale	5.4±1.6	2.3±1.4	4.7±1.9	2.9±2.0
Fatima et al (2021) 21)	Numerical Pain Rating Scale	5.64±0.49	1.0±0.57	5.57±0.51	2.77±1.09
Javdaneh et al (2021) 23)	Visual Analogue Scale	56.75±8.54	28.41±8.78	57.91±9.94	57.41±8.95
Javdaneh et al (2020) 24)	Visual Analogue Scale	59.70±6.15	12.35±4.74	57.15±6.33	31.55±5.15
Yildiz et al (2018) 8)	Visual Analogue Scale	4.7±1.9	1.2±1.4	4.4±1.4	1.1±1.3

Meta-analysis was performed to identify the effects of scapular interventions on pain and disability. Meta-analysis was performed to identify the effects of scapular interventions on pain. Pooling the results of six studies, that assessed the effect of scapula interventions on neck pain, there was a significant difference between the scapula interventions and only neck interventions group (total effect: SMD −1.83, 95% CI [−3.33, −0.33], z=2.39, p=0.02). The effect of isolated scapular interventions on neck pain could not be studied due to a limited number of studies directly comparing the two interventions (Fig. 4).

Figure 4.

Forest plot for effect of scapular interventions on pain.

Disability

Three^8,21,22) among the five studies only evaluated the disability scores. Both the studies have used Neck Disability Index. Table 5 shows the summary of disability score with scapular interventions.

Table 5.

Summary Results of Disability Score with Scapular Interventions.

Study ID	Disability Scale Used	Disability Score Preintervention	Disability Score Postintervention	Disability Score Precontrol	Disability Score Postcontrol
Alshami et al, (2021) 22)	Neck Disability Index	25.7±10.5	16.1±10.1	27.4±14.1	15.1±8.8
Fatima et al (2021) 21)	Neck Disability Index	35.26±8.8	6.97±2.72	36.94±9.36	12.55±2.45
Yildiz et al, (2018) 8)	Neck Disability Index	13.8±2.8	5.9±3.1	15.2±4.6	5.2±3.4

On assessing the effect of scapula interventions on disability, the results revealed that there was no significant (p=0.40) impact. Subgroup analysis on the effect of isolated scapular interventions was not performed on disability as meta-analysis was not possible with a single study (Fig. 5).

Figure 5.

Forest plot for effect of scapular interventions on disability.

Quality of life

None of the studies evaluated the quality of life in patients with neck pain.

Discussion

This systematic review and meta-analysis aimed to identify the effects of scapular interventions on pain and disability in patients with neck pain. The results of this review found that the combined effect of scapular interventions and neck exercises has a significant effect on pain but not on disability.

To the best of our knowledge, this is the first systematic review and meta-analysis to compare the effect of scapular interventions on pain and disability in patients with neck pain. The results of this review show that there was a significant effect associated with scapular interventions with neck exercise on pain when compared to neck exercises alone (p=0.02) in individuals with mechanical neck pain. Results of the meta-analysis showed that there is a large effect on pain. A few recent systematic review and meta-analysis have also provided a similar effect of exercises on pain. Wu B et al., (2020)²⁵⁾, Zoete RMJ (2020)²⁶⁾, and Bertozzi et al. (2013)²⁷⁾ have found that there was a significant improvement in pain with a shorter duration of the intervention. These studies compared the effect of different therapeutic exercises, stabilization exercises, and physical exercises, making it incomparable to the present review.

Previous studies have shown that strengthening exercises are effect in the management of individuals with neck pain. Targeting exercises directed toward scapular muscles has recently gained attention as the scapula plays a major role in the biomechanics of the neck. Any alteration in the scapula's position could lead to an uneven weight distribution through the cervical spine, making the scapula a key factor in the treatment of patients with neck pain²⁸⁾. It has been shown that mechanical neck pain is frequently accompanied by scapular dyskinesis^4,28). Altered neuromuscular regulation of the axioscapular muscles is one of the causes of scapular dyskinesis. Specifically, when performing upper limb tasks, the serratus anterior and upper, middle, and lower regions of the trapezius muscles exhibit different activity patterns^29,30). Recent studies have shown that an abnormal position of scapula in patients with neck pain and active strengthening of scapular muscles may be beneficial in treating individuals with neck pain^14,31).

Correction of the scapular position may decrease aberrant cervical loads and axioscapular muscle tension, which in turn could potentially decrease pain^32,33). All included in this systematic review addressed strengthening of the axioscapular muscles. Addressing these deficiencies may improve muscular balance and restore the normal mechanism. A recent systematic review concluded that scapular stabilization exercise could potentially be effective for managing nonspecific neck. The review reported a lack of strong evidence and the study was difficult to generalize due to the methodology used in the study¹⁷⁾. The present review differs in that a number of recent literature reviews did not provide evidence on the combined effects of scapular and neck interventions on reducing pain in individuals with neck pain.

The pooled results of the included studies found that there was no significant effect of combined scapular interventions and neck exercises on disability (p=0.40). This finding was in agreement to the short and intermediate effect of exercise on disability found by Bertozzi et al. (2013)²⁷⁾. In contrary to the findings of this study, it is also noted that Bertozzi et al. (2013)²⁷⁾ and Wu B et al. (2020)²⁵⁾ reported that there is a significant improvement in disability with a long-term follow-up. A recent systematic review concluded that the scapular strengthening exercises are effective in improving neck disability due to lack of evidence. The differences in the findings of this present review might be due to the different follow-up time used in the different studies. The rationale for improvement in neck disability with a long-term follow-up can be attributed to the cognitive behavioral models of pain. Disability being a subjective entity, reduction in pain, and change in thoughts about the anticipated harm can lead to improved pain-related cognitions and emotions. Moreover, physical therapies in controlled environment have been shown to contribute to the improvement in cognitive and emotional changes³⁴⁾.

Due to a limited number of studies, the isolated effect of isolated scapular interventions on pain and disability could not be determined with certainty. A meta-analysis was not performed due to the heterogenous nature of the studies included in managing individuals with neck pain. Further randomized controlled trials that focus on the isolated effect on pain and disability are necessary to test this hypothesis.

Limitations

The limitation of this review includes a small sample size of included studies. The overestimation of treatment effect is more likely to happen in small trials. A high heterogeneity was also observed in this review, which may be due to the difference in methodology and duration between the studies. One of the intended scopes of this review was to examine the effect of isolated scapular interventions on pain and disability in patients with neck pain, but due to a limited number of studies, it was not possible for us to establish its effect. Thoracic spine kyphosis that also a plays an important role in the movements of scapula was also not addressed in the study.

Conclusion

From the pooled results, we conclude that scapular and neck interventions in combination are effective in reducing pain in patients with neck pain. However, it was not effective in improving the disability. Future studies are needed to examine the long-term effects of scapular interventions on disability and quality of life in patients with neck pain.

Conflicts of Interest: The authors declare that there are no relevant conflicts of interest.

Sources of Funding: None

Author Contributions: Nithin Prakash: Conception, study design, data analysis, and manuscript preparation.

Karvannan Harikesavan: Conception, study design, data analysis, and supervision.

Joshua Cleland: Supervision, data analysis, and critical review.

Ethical Approval: Not applicable. The study is a systematic review and meta-analysis and no human subjects are involved.

Informed Consent: Consent was not required because this study involved no human subject.