Effectiveness of manual thoracic therapy in treating impingement syndrome: a systematic review

Shoulder impingement syndrome is emerging as a complex and multidimensional pathology, involving a variety of etiological and biomechanical factors [2, 13]. Characterized by compression of subacromial structures, the syndrome leads to a clinical picture of pain, weakness, and paresthesia in the upper limb. Originally described by Adam in 1852 [34], the pathology was widely disseminated and characterized by the work of Charles Neer in 1972 [17], highlighting the reduction of subacromial space as a key element in the pathogenesis of the syndrome [13]. The classification of subacromial conflict syndrome, developed by Neer in 1983 [18], divides the condition into three stages based on the patient’s age, clinical signs, and the evolution of the pathology. These stages range from edema and inflammation, typical in individuals under 25 years, to fibrosis and tendinitis in patients aged 25 to 40 years, up to the development of bone spurs and tendon ruptures in individuals over 40 years. It is important to note that impingement syndrome can be further classified based on the nature of the conflict, distinguishing between primary conflict, secondary conflict, and internal impingement [14, 37]. These subclassifications are based on differences in etiology and clinical presentation, such as the abnormal relationship between the rotator cuff and the coracoacromial arch in primary conflict, glenohumeral or scapulothoracic instability in secondary conflict, and contact between the greater tuberosity and the posterior–superior face of the glenoid in internal impingement [12, 33]. In addition, a significant link has been identified between impingement syndrome and various biomechanical factors such as alterations in scapular kinematics, abnormal muscle activation, and incorrect posture [1, 4, 19, 21, 23, 25, 26]. Recent studies have emphasized how increased thoracic kyphosis can contribute to the pathology, altering scapular mechanics and reducing the subacromial space [33]. This systematic review focuses on exploring the efficacy of manual therapy techniques, particularly those applied to the thoracic district, in patients with subacromial conflict syndrome [27, 29, 32]. The objective is to assess how these interventions influence pain, functionality, scapular kinematics, and muscle strength compared to other therapeutic methods or the absence of treatment [27, 28, 31]. Considering the importance of regional interdependence and the influence of scapular kinematics in the syndrome, this review offers a critical and updated evaluation of therapeutic options, with a particular focus on the short- and long-term outcomes of different therapeutic approaches [5‐11, 22, 24, 30, 35].

This systematic review was carried out following the methodological guidance contained in the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) checklist [20]. The protocol was published in the International Prospective Register of Systematic Reviews (PROSPERO) under registration number CRD42023491212.

From the initial search, 140 articles were retrieved. Specifically, 28 articles were found in PubMed, 72 in PEDro, and 40 in Cochrane. Of these articles, 76 were removed as duplicates, resulting in a total of 64 articles. With the first reading of titles and abstracts, 37 studies were removed. After the full reading of the remaining studies, 18 studies were eliminated for not meeting the inclusion criteria. Thus, 9 articles were included in the review (Table 1). The entire study selection process is outlined in the PRISMA statement flow diagram (Fig. 1), which details the excluded studies and the reasons for their exclusion.

The objective of this review was to evaluate whether manual therapy techniques applied to the thoracic district can provide benefits in terms of pain or functionality in patients with impingement syndrome. This review also included studies where, in addition to thoracic manual therapy, therapeutic exercise was performed or part of the treatment was directly dedicated to the shoulder, as this is the standard approach for patients with subacromial conflict syndrome. In the majority of the studies [7, 9‐11, 22, 24], only manipulative techniques at the thoracic level were applied. Riley’s study [22] associated a “row” type reinforcement exercise, Land’s study [11] a supine postural exercise, and Hunter’s study [8] performed a muscle energy technique (MET). Six studies [5‐7, 9, 10, 24] used a sham manipulation as a control group, described in the study by Michener et al. [16] as a valid comparative tool. The four outcomes investigated by this review are pain, functionality, scapular kinematics, and muscle activation. Regarding pain, all authors agree that following treatment, the intervention groups do not show substantial differences compared to placebo groups. However, in all studies, there was a reduction in pain (NPRS) between 0.6 and 1.5 points in the immediate post-treatment period, with a maximum of 3.2 in the follow-up. Specifically, Haik’s study [7] reported a difference of 0.6 points NPRS post-intervention, Kardouni’s study [10] 1.1 points NPRS post-treatment, and 1.5 at the 24/48 h follow-up. Kardouni’s second study [9] had a 1-point NPRS difference post-treatment and 1.2 at the 24/48 h follow-up. Riley’s study [22] found an average difference of 0.9 points NPRS between pre-treatment and 6/9 days follow-up. Haik’s second study [6] found a difference of 0.8 points on the second day of intervention and 0.9 immediately after the second intervention. Land’s study [11] found a 3.6-point NPRS reduction after 12 weeks of treatment. Da Silva’s study [24], which used the VAS scale, achieved a 0.53-cm reduction. Finally, Hunter’s study [8] demonstrated a VAS pain reduction of 1.5 cm at discharge, 1.4 at the 6‑month follow-up, and 1.7 at the 12-month follow-up. For some authors, the average reduction in scores describing pain is attributed to the factor of time; this would explain the similarity with the scores of various placebo groups. Authors who conducted trials with analysis of outcomes immediately after treatment believe that the reduction in pain is caused by the placebo effect, patient positioning, interaction with a healthcare professional, or mobilization within the range of motion. For the outcome of functionality, as with pain, the majority of studies agree that intervention groups and placebo groups do not show differences. However, in some studies there have been statistically significant changes in assessment scale scores post-treatment or during follow-up. Specifically, Kardouni’s studies [9, 10] show a decreased Penn Shoulder Scale score by 10.1 and 9.1 points, respectively, in the 24/48 h follow-up. Riley’s study [22] achieved an 8‑point improvement in the SPADI scale between pre-treatment and 6/9 days follow-up. Land’s study [11] found a 32-point improvement in the SPADI scale in the thoracic intervention group at 12 weeks, and the results were maintained up to the 12-month follow-up. Hunter’s study [8] found an improvement in the DASH and SPADI scales both at discharge with 8.4 and 14.7 points of difference, at the 6‑month follow-up with 11.1 and 14.9 points of difference, and at 12 months with 13.4 and 19 points of difference compared to the placebo group, respectively. Regarding the outcome of scapular kinematics, there was heterogeneity in results, as some studies had significant changes, while others found no differences. Haik’s study [7] reported improvements following manual therapy in both symptomatic and asymptomatic groups, with the symptomatic group showing an increase of 1.7° in lateral scapular rotation during elevation and 1.1° during lowering. The asymptomatic group showed an increase of 2.2° in lateral scapular rotation during elevation and 1.9° during lowering. The asymptomatic group also showed an increase of 0.9° in scapular tilt during elevation and 1.1° during lowering. Kardouni’s study [9] reported scapular improvements in medial rotation of 0.9° in both groups during elevation and 0.8° during lowering. Haik’s second study [6] found an increase in lateral scapular rotation of 2.6° during elevation, improving to 4.6° after the second treatment. This improvement in lateral rotation was also observed during lowering by 4°, improving to 5.3° after the second intervention. Da Silva’s study [24] measured shoulder range of motion globally, indicating significant improvements in flexion and abduction movements by 3.5° and 8.0°, respectively, as well as improved abduction by 2.0° in the non-painful shoulder. Land’s study [11] reported an improvement in passive internal shoulder rotation of 17.0° at 6 weeks and 19.8° at 12 weeks. The last outcome, muscle activity, was measured in Haik’s study [6], where increased activity of the upper trapezius and decreased activity of the lower trapezius were observed following manipulative therapy, in both flexion and lowering arm movements. Grimes’s study [5] found no differences in isometric strength of the trapezius or serratus anterior muscles or in the length of the pectoralis minor muscle after performing manipulations. Some results obtained from various studies are described by the authors as “statistically significant but not clinically important,” as minimal variations in pain and functionality scales or a few degrees in scapular range of motion can be important statistically but hardly translate into real changes in clinical practice. This review aims to verify the efficacy of thoracic manual therapy not to completely replace the standard treatment but more to integrate it within it and understand whether applying these techniques can speed up the healing process and pain reduction in patients.

This review indicates that manual thoracic therapy may reduce pain in impingement syndrome, but due to methodological limitations and variability in treatment application, further research is needed to confirm its efficacy in clinical practice.