“The Dark Side of Musculoskeletal Care”: Why Do Ineffective Techniques Seem to Work? A Comprehensive Review of Complementary and Alternative Therapies

Abstract

The increasing interest in complementary and alternative medicines (CAMs) for musculoskeletal care has sparked significant debate, particularly regarding their biological plausibility and clinical effectiveness. This comprehensive review critically examines the use of two of the most widely utilized CAMs—osteopathy and chiropractic care—over the past 25 years, focusing on their biological plausibility, clinical effectiveness, and potential mechanisms of action. Our analysis of current research and clinical studies reveals that osteopathy and chiropractic are based on concepts such as “somatic dysfunction” and “vertebral subluxation”, which lack robust empirical validation. While these therapies are often presented as credible treatment options, studies evaluating their effectiveness frequently exhibit serious methodological flaws, providing insufficient empirical support for their recommendation as first-line treatments for musculoskeletal conditions. The effects and mechanisms underlying osteopathy and chiropractic remain poorly understood. However, placebo responses—mediated by the interaction of contextual, psychological, and non-specific factors—appear to play a significant role in observed outcomes. The integration of therapies with limited biological plausibility, whose effects may primarily rely on placebo effects, into healthcare systems raises important ethical dilemmas. This review highlights the need for rigorous adherence to scientific principles and calls for a more comprehensive investigation into biobehavioral, contextual, and psychosocial factors that interact with the specific effects of these interventions. Such efforts are essential to advancing our understanding of CAMs, enhancing clinical decision-making, promoting ethical practices, and guiding future research aimed at improving patient care in musculoskeletal disorders.

1. Introduction

Musculoskeletal care as a health discipline has seen significant advancements in recent years, largely driven by the adoption of evidence-based approaches. However, a concerning phenomenon persists: the continued use of therapies within musculoskeletal care that lack empirical support and even biological plausibility. In this sense, the use of complementary and alternative medicines (CAMs) has shown an increase in various regions worldwide, with notable variations. For instance, in Europe, their use has risen from 26% to 40% in recent years, with countries such as Germany and Denmark leading these statistics [1,2]. Similarly, in the United States, a comparable increase has been observed [3,4]. On the other hand, in Asia, CAMs enjoy significant social and institutional acceptance, which fosters an even greater inclination toward their use, particularly in countries such as China, the Philippines, and South Korea [5].

Despite efforts by part of the healthcare community to promote evidence-based practices, the previous statistics showed that contemporary musculoskeletal care remains influenced by the historical adoption of CAMs that lack scientific backing. This phenomenon has gained traction despite the lack of empirical evidence due to the growing demand from patients for more integrative and holistic approaches, often as a response to dissatisfaction with conventional medicine and its associated adverse effects [6,7]. However, the popularity of a therapy is a poor indicator of its effectiveness, and interventions must demonstrate their true value through methodologically rigorous studies.

The most described negative experiences with conventional medicine range from unfavorable interactions between professionals and patients to perceptions of inefficacy and the side effects of traditional treatments [8]. However, the rejection of conventional medicine or poor perception of healthcare systems are not the only factors driving the use of CAMs. On the contrary, users of these therapies often are proactive individuals who choose their own treatments, seeking approaches they consider most effective [9]. Additionally, many of these practices, seemingly grounded in science, are used by healthcare professionals, which can generate greater confidence in their adoption by the public [8].

To illustrate this situation, consider pharmacological treatments for headaches, which are typically the first line of intervention for patients [10,11]. However, these medications are not without risks, and approximately one-third of headache patients report dissatisfaction with the results [12]. Consequently, many turn to CAMs, such as chiropractic care [13,14] or osteopathy [15].

CAMs are defined as “a diverse set of medical and healthcare systems, practices, and products that are not currently considered part of conventional medicine” [16]. They are characterized by a limited number of clinical trials supporting their hypotheses or testing methods to evaluate their results in diverse conditions, as they were originally considered outside of evidence-based practices. However, this situation has evolved, and numerous journals specializing in complementary and alternative therapies have been established and categorized within the Journal Citation Reports of the Web of Science database under Integrative and Complementary Medicine [17].

A clear distinction between complementary and alternative interventions must be pointed out. Complementary therapies, on the one hand, accept various models of disease and are open to being used alongside evidence-based conventional therapies. Alternative therapies, on the other hand, propose a unique model of disease that attempts to explain the entire complexity of health and illness [18]. Examples related to musculoskeletal care include osteopathy with its “law of the artery” and chiropractic care with its “law of the nerve” [19]. These types of therapies often resist verification and falsity, where verification is understood as the biological plausibility of their hypotheses and falsity as admitting that if their effects are not superior to a placebo, they cannot be considered evidence-based techniques [20,21].

The classification of these CAMs indicates that none have been subjected to rigorously designed and executed scientific studies that address essential questions such as their biological plausibility or clinical effectiveness. In contrast, when these therapies respond favorably to the scientific method, they are removed from the lists of CAMs and integrated into the repertoire of evidence-based techniques [22]. The importance of this discussion lies in the fact that in the best-case scenario, CAMs may not have a direct adverse effect. However, for many patients, they can be counterproductive by significantly delaying appropriate treatment and preventing or interfering with access to quality healthcare based on the scientific method [23].

In this context, there is a growing need for a critical comprehensive review of CAMs used in musculoskeletal care, focusing on their biological plausibility, clinical effectiveness, and the factors involved in clinical responses and effects, including potential mechanisms of action, contextual factors, placebo response, and psychological influences such as cognitive biases (Figure 1).

This review aims to examine these key dimensions while maintaining a balanced perspective, offering practical implications for both clinical practice and future research. Specifically, it is intended to provide guidance on the appropriate integration of CAMs as a first line for musculoskeletal care. Furthermore, the review highlights the necessity for robust, high-quality studies to address existing gaps in evidence, fostering open and constructive dialogue among healthcare professionals. This balanced approach is intended to support evidence-based decision-making, promote ethical clinical practices, and encourage the advancement of integrative healthcare research.

2. Methodology of Literature Search

This critical comprehensive review was conducted following a different search strategy to identify relevant literature on CAMs used in musculoskeletal care [24]. The search was performed in multiple databases, including PubMed, Scopus, Web of Science, and Cochrane Library. The search was limited to articles published in English, spanning from January 2000 to January 2025. A manual search of reference lists from included articles was also conducted to ensure that no significant studies were omitted.

Eligibility Criteria

Study selection for this narrative review followed predefined inclusion and exclusion criteria to ensure methodological rigor and alignment with the research objectives.

Eligible studies were those investigating the biological plausibility, underlying mechanisms of action, or clinical efficacy of CAMs, specifically osteopathy and chiropractic, in musculoskeletal care. The study types included narrative reviews, systematic reviews, meta-analyses, original research articles, theoretical papers, and opinion/commentary articles. This broad scope allowed for the generation of hypotheses regarding the mechanisms underlying the use of CAM in musculoskeletal health. The comprehensive approach adopted in this review facilitated the inclusion of diverse sources, enriching the understanding of CAM’s role in musculoskeletal care.

Studies were excluded if they focused on non-musculoskeletal conditions or primarily addressed psychological or wellness outcomes that were not directly relevant to musculoskeletal care. However, studies examining psychological effects (e.g., biases, anxiety, depression) as part of a broader analysis of CAM interventions in musculoskeletal conditions were included when they provided meaningful insights into the overall impact on patient well-being.

3. Biological Plausibility of CAMs

The discussion surrounding the biological plausibility of osteopathy and chiropractic in musculoskeletal care is a crucial aspect that demands careful analysis. Understanding the challenges inherent in the theoretical models underpinning these therapies is essential for evaluating their validity.

According to Koterov [25], biological plausibility serves as a fundamental pillar for establishing causal relationships in epidemiological research and health sciences. The concept rests on the premise that a causal link should conform to the prevailing scientific theories and align with the body of biological knowledge available. For an association to be deemed causal, it is essential to identify a coherent biological pathway that clarifies how one factor might influence another. In the absence of such a model, it is difficult to definitively confirm causality. This becomes especially critical in public health, where decisions regarding prevention and safety standards hinge on the validity of the scientific basis supporting the therapies being recommended or implemented [25].

3.1. Biological Plausibility of Osteopathy

Osteopathy was founded by the American physician Andrew T. Still, and claims that “somatic dysfunctions” in the musculoskeletal system are linked to both musculoskeletal and non-musculoskeletal conditions, considering osteopathic manipulative treatment as the main intervention to treat these dysfunctions. Somatic dysfunctions can affect the skeletal, vascular, and neural systems and can originate pain, organ dysfunction, or impaired systemic health, highlighting the interconnection between the musculoskeletal system and other body systems [26]. This approach suggests that osteopathic manipulative treatment can address a wide array of clinical conditions, from substance abuse to musculoskeletal pain. However, this broad application risks undermining the scientific credibility of osteopathic practice, potentially leading practitioners to disregard established scientific consensus and perpetuate epistemological gaps in their practice [27].

Osteopathy is based mainly on three large groups of treatments or interventions: structural osteopathy, craniosacral osteopathy, and visceral osteopathy.

Structural osteopathy places emphasis on the interconnectedness of body systems and the body’s inherent self-healing capabilities. Dysfunctions within the musculoskeletal system may affect visceral organs via somatovisceral reflexes, while visceral pathologies may present as restricted movement or modification in the tissue consistency in the musculoskeletal system, termed viscerosomatic reflexes [26]. Osteopathic manipulative treatment aims to correct these dysfunctions by relieving pain and improving range of motion, as well as improving neurovascular and lymphatic flow [26,28]. However, the efficacy of this approach is highly dependent on the identification of “somatic dysfunctions”, a process with limited inter-rater reliability between practitioners [29].

Craniosacral osteopathy is based on the premise that alterations in the mobility of cranial sutures can cause diseases, disorders, or dysfunctions. It is argued that a disruption in the “mobility” of the sphenobasilar synchondrosis could lead to disturbances throughout the cranial complex, a diagnosis typically made through specific palpatory assessment by an osteopath. This approach often employs general concepts of proven biological phenomena to infer that similar processes occur within the osteopathic model. For instance, rhythmic movements observed from the cellular level to the cardiac level are used to suggest that the craniosacral system and its surrounding structures must exhibit a similar oscillatory rhythm [30]. However, it is noteworthy that findings from magnetic resonance imaging (MRI), which suggest that the skull might exhibit dimensional variations of 0.898 mm/pixel (less than a millimeter) [31], are often dismissed due to potential interpretation errors [30]. These results could stem from vestibular system stimulation, generating rhythmic head movements. Nevertheless, there is skepticism about the ability of manual therapists to perceive these submillimetric changes with their hands, as such variations fall outside the resolution capacity of MRI [31,32].

Finally visceral osteopathy proposes that manual manipulation can improve the mobility of internal organs and restore their function, based on the idea of interconnection between visceral and musculoskeletal structures [33]. However, studies investigating this supposed visceral mobility through osteopathic techniques have yielded inconsistent and inconclusive results. Moreover, the biomechanical and physiological principles supporting this notion lack grounding in human anatomy and physiology. While it is observed that viscera exhibit mobility during vital functions such as breathing and activities like running and jumping [34], a clear causal relationship between the alleged alteration of visceral mobility in various clinical conditions and the manual manipulations intended to restore it has not been established. Furthermore, osteopathy often falls into the fallacy of anatomical possibilism, exaggerating anatomical-functional relationships to the point of implausibility [35]. Additionally, the reliability of diagnostic techniques used in visceral osteopathy lacks solid evidence, and there is no consensus on the existence of “somatic dysfunction” [36,37].

3.2. Biological Plausibility of Chiropractic

Chiropractic was founded by David Palmer and is mainly based on the theory of “vertebral subluxation”, which claims that misaligned vertebrae can cause interference in the nervous system, subsequently affecting the function of other bodily systems, such as the immune system, and contributing to the development of diseases [38,39]. However, this theory has sparked intense debate and controversy within the scientific community due to the lack of robust evidence supporting its biological plausibility [40,41]. Moreover, the treatment for this proposed complex and multisystemic dysfunction involves spinal manipulation or chiropractic adjustment, which many consider an effective tool for relieving ailments and improving neurological function [42]. Proponents of chiropractic argue that these are specific assessments and maneuvers aimed at correcting vertebral subluxations. Nevertheless, studies have shown that segmental vertebral evaluation and manipulations cannot be specifically applied to a particular vertebra and that their limited effects are based on nonspecific mechanisms [43].

In the discussion of new causal mechanisms, two general errors or biases can occur, identified as “the believers and the skeptics” [44]. The first error, the believer’s error, is inferring the existence of a causal mechanism when it does not exist where osteopathy, chiropractic care, and other CAMs may fall. The second, the skeptic’s error, is inferring the nonexistence of a causal mechanism that exists, an error we must strive to avoid until evidence suggests otherwise. In this sense, osteopathy and chiropractic describe a causal mechanism that is not supported by biological bases; therefore, its effects may rely on non-specific, placebo, and contextual factors [45,46]. On the other hand, conventional interventions such as exercise have described multiple mechanisms of action with strong biological bases, specific effects and long-term effects.

The reviewed articles encompass a wide range of study types, including observational studies, reviews (narrative, systematic, and conceptual), and educational model validations. Interventions analyzed focus primarily on osteopathy, chiropractic care, visceral mobilization, and spinal manipulation. Populations studied ranges from the general public to patients with spinal pain, pediatric groups, and osteopathy students. Key outcomes include assessments of clinical efficacy, biological plausibility, and theoretical mechanisms. However, the studies are frequently limited by theoretical frameworks, small sample sizes, and a lack of robust experimental evidence. The reader can find the studies analyzed in Appendix A.

4. Clinical Effectiveness of Osteopathy and Chiropractic in Musculoskeletal Care

4.1. Clinical Effectiveness of Osteopathy

Osteopathy, encompassing structural, visceral and craniosacral techniques, has been subject of debate regarding its efficacy in musculoskeletal care. Although the effectiveness of pragmatic osteopathy has been studied in some systematic reviews with meta-analyses [47,48,49,50,51], and associated with small statistical effects on clinical outcomes, the methodological flaws identified cast doubt on the positive results. The most important biases found were the inclusion of congress abstracts, pilot studies that do not aim to evaluate clinical effectiveness, and unpublished materials from osteopathic institutions as relevant studies. Recent systematic reviews with meta-analyses with more robust methodological approaches found that pragmatic osteopathic manipulative treatments, and visceral and craniosacral osteopathy in isolation produced no statistically significant effects on clinical outcomes on patients with musculoskeletal or non-musculoskeletal disorders [36,52,53,54,55,56,57,58]. Specifically, a recent systematic review and meta-analysis demonstrated that the pragmatic application of osteopathic manipulative treatment was not superior to sham or placebo interventions for patients with neck and low back pain. This finding suggests that the effects of osteopathy may be attributed more to placebo effects than to specific therapeutic mechanisms [29].

Several critical methodological issues and biases have been identified in primary clinical trials. One of the most significant concerns is the diagnosis based on the manual palpation of so-called somatic dysfunctions, whose reliability has been shown to be questionable due to poor inter-examiner agreement and the inability to standardize this method. Additionally, there is a lack of standardization in the parameters of the techniques employed, such as the applied force, the duration of the interventions, and the pragmatic application based on palpatory findings.

Other relevant factors include the use of placebo techniques with questionable efficacy, the absence of proper evaluation of masking effectiveness, the use of small sample sizes, and the presence of groups with high variability and elevated standard deviations. These methodological shortcomings significantly undermine the robustness and validity of the results obtained [56,59,60,61,62].

4.2. Clinical Effectiveness of Chiropractic

Chiropractic care faces similar scrutiny regarding its clinical effectiveness. It is often criticized for lacking a plausible biological model for its interventions. While short-term improvements in spinal symptoms are modest, these often lack clinical significance [63,64]. Moreover, chiropractic interventions have not demonstrated superiority over other treatments, and their effectiveness compared to placebo or no intervention remains questionable [65,66]. The use of chiropractic care for conditions unrelated to the spine is not supported by evidence [67].

Spinal manipulation is the cornerstone of chiropractic care and has been associated with frequent mild adverse effects and, in rare cases, severe complications of unknown incidence [68]. Chiropractors appear to have the highest number of adverse events following manipulations among healthcare professionals [69], while the low quality of evidence regarding sham manipulation introduces further uncertainty in comparisons between interventions.

The reader can find the studies analyzed in Appendix B.

5. Effects and Potential Mechanisms of Osteopathy and Chiropractic in Musculoskeletal Pain

The overall treatment effect is divided into three interacting factors: specific, contextual, and non-specific. Specific effects are clinical changes due to the direct mechanisms of the intervention. Contextual effects, on the other hand, result from the therapeutic encounter and the context of the health care system. Finally, non-specific effects, such as the natural course of the disease or regression to the mean, influence the clinical response but are not related to the intervention. The sum of contextual and non-specific effects is called the placebo response, based on changes perceived by the patient independently of the specific effects [45,46]. It is important to clarify that these factors influence each other and cannot be completely isolated (Figure 2).

5.1. Specific Factors in Osteopathic and Chiropractic Practices for Musculoskeletal Care

Specific factors for osteopathy and chiropractic have not been clearly demonstrated yet. Spinal manipulation therapy (SMT) is probably the most investigated technique that has shown some biological plausibility and is a common technique used by both osteopaths and chiropractors.

SMT is proposed to alleviate musculoskeletal pain through various neurophysiological mechanisms. At the peripheral level, the spinal manipulation may reduce proinflammatory cytokine activity and oxidative stress, potentially mitigating inflammation and peripheral sensitization [66]. At the spinal level, SMT is believed to induce segmental inhibition, which decreases temporal summation of nociceptive signals, thereby dampening central sensitization processes [71,72]. These effects have been observed in increased pain pressure thresholds in corresponding dermatomes and myotomes, as well as reduced sensitivity to thermal stimuli [73].

However, while SMT influences these neurophysiological parameters, these changes often fail to correlate consistently with improvements in pain, stiffness, or functional outcomes [74]. Furthermore, descending inhibitory pathways may contribute to reduced pain perception, but it remains unclear whether this is a specific result of SMT or attributable to non-specific or contextual factors [75]. It has been proposed that efforts are needed to improve the quality of studies and methods in order to know whether there are specific effects of these interventions and what their real contribution is to the overall effect of clinical outcomes [76].

5.2. Placebo Response: Interaction Between Non-Specific and Contextual Factors in Osteopathic and Chiropractic Practices for Musculoskeletal Care

The placebo and nocebo effects are therapeutic responses that arise independently of the intrinsic efficacy of an intervention. Specifically, the nervous system determines whether a treatment response is perceived as favorable or not [77,78,79]. These phenomena, which can be either positive or negative, are rooted in behavioral, emotional, and cognitive modulation [78,79].

The placebo response encompasses a wide range of factors, including personality traits [80,81], the patient–therapist relationship [82,83], cultural influences [84,85], genetics [78], conditioned responses [86], observational learning [87], descending modulation mechanisms [88], and brain dynamics [79,89]. These factors seem to contribute significantly to the outcomes observed in CAMs [90]

The placebo response is inseparable from clinical practice and is triggered by the sum of the interaction of contextual and non-specific factors. However, it is important to note that relying on therapies that depend solely on the manipulation of these factors leads to clinical responses with great variability and unpredictability [91,92]. Furthermore, the long-term stability of these effects is uncertain, suggesting that they may be of limited value and may interfere with appropriate treatments [93]. CAMs may also generate a nocebo response, which could worsen the patient’s condition.

Contextual and psychological factors are fundamental to the placebo phenomenon [84,94]. Therapies such as osteopathy or chiropractic often leverage these elements, intentionally or not [95]. For instance, in conservative, primarily passive treatments for patients with non-specific chronic low back pain, about half of the overall treatment effect can be attributed to non-specific effects that occur without any treatment rather than to specific effects or placebo effects induced by the therapies [96].

It is important to recognize that the placebo response represents only one facet of the numerous variables influencing the interaction between a patient, therapist, and clinical situation. The outcomes of any given intervention can be affected by non-specific effects, such as the natural history of the disease, regression to the mean [46], or the expectations generated by the therapy [97].

5.3. Cognitive-Mediated Effects and Bias in Osteopathic and Chiropractic Practices for Musculoskeletal Care

Emotional, cognitive, and social factors play a pivotal role in how individuals respond to therapy. The attention, care, emotional support, and explanations provided during treatment can significantly influence the patient’s experience, irrespective of the treatment’s actual efficacy [90].

The meaning attributed to a symptom and the approach taken towards it are crucial in determining the therapeutic response. For example, postoperative pain, which may be perceived as part of the healing process, can be experienced and tolerated differently compared to pain associated with a terminal illness, which is often linked to death and a palliative approach [98]. Some CAMs offer alternative narratives that allow patients to reinterpret their experiences, thereby enhancing their psychological well-being. Participation in therapy groups or communities that support these practices can provide a sense of belonging and social support, which contributes to emotional well-being [99,100,101].

These psychological responses are further influenced by cognitive biases defined as systematic patterns that can distort perception, memory, and reasoning and lead to erroneous conclusions or suboptimal decisions [102]. Such biases can arise from altered information processing [103], past experiences [104], personal beliefs and learning about health, illness, and care processes [102,105] as well as social and cultural influences [102].

The literature highlights several cognitive biases, such as causality bias and authority bias, that appear to play an important role in the therapeutic context. Furthermore, biases such as optimism bias, illusion of control bias, and confirmation bias may also influence the dynamic between patient and therapist, potentially shaping treatment perceptions and outcomes.

Causality bias occurs when a specific outcome is mistakenly attributed to a particular action, often due to a low demand for evidence [103,105]. Individuals prone to this bias tend to attribute any change in their health to a practice that aligns with their beliefs or previous experiences [106].

Authority bias occurs when the opinion of an expert, such as a health professional, is deemed sufficient for decision-making by the patient [107]. Research has shown that many health practices not supported by scientific evidence are recommended by professionals, who may themselves have limited understanding of the practice they endorse [108,109,110].

Optimism bias reflects the tendency to overestimate positive outcomes and underestimate potential risks [111], which can lead patients to believe that these therapies are inherently safe or more effective than the evidence suggests.

Illusion of control bias refers to the belief that one can influence outcomes beyond actual control; this can reinforce both patient and practitioner confidence in these interventions, even when objective evidence is lacking [111,112].

Confirmation bias further compounds these effects by particularly driving professionals to selectively interpret information that aligns with their pre-existing beliefs and dismiss contradictory evidence, thereby negatively interfering with clinical reasoning [109,113,114]. These cognitive distortions not only bias clinical decision-making but also highlight the importance of fostering critical thinking and promoting evidence-based practices to mitigate the impact of these biases in musculoskeletal care.

Additional psychological effects relevant to the interpretation of CAMs include the Barnum effect and the Hawthorne effect. The Barnum effect, often exploited in pseudoscientific fields, occurs when individuals perceive vague and generic descriptions as highly accurate and personalized [115]. In practices like osteopathy and chiropractic, this effect leverages patients’ desires for diagnostic certainty and the need to identify predictable patterns in their health, fostering a sense of personal connection with the treatment and practitioner [116,117,118]. This perceived personalization can bypass critical reasoning, leading patients to trust vague explanations and interpret ambiguity as hidden meaning, which reinforces their belief in the therapy’s effectiveness despite a lack of scientific evidence [119]. As a result, emotional shortcuts in decision-making may drive continued adherence to such treatments, amplifying their perceived benefits [120].

The Hawthorne effect suggests that patients may modify their behavior and report therapeutic improvements simply due to their participation in treatment that includes regular and personalized follow-up by the therapist. This phenomenon is particularly evident in therapies where the evaluation criteria are subjective, such as pain or “dysfunction” [121]. Patients might exaggerate symptom improvements to align with the therapist’s expectations, leading to an overestimation of treatment efficacy in both effective and ineffective approaches [122,123]. Additionally, the exposure to a therapeutic ritual with promised results can shape symptom perception and evaluation, with many patients confirming expected changes to satisfy the therapist [123].

While these psychological factors are common to varying degrees among all individuals, certain traits appear to increase susceptibility to persuasion by these types of therapies and narratives. Characteristics such as agreeableness, introversion, and lack of premeditation are associated with greater susceptibility [124,125].

The studies used in this section employ diverse methodologies, including experimental research, surveys, qualitative studies, systematic reviews, and meta-analyses. They examine psychological elements such as placebo effects, cognitive biases, pseudoscientific beliefs, causal illusions, and the “Guru Effect”, with populations including CAMs users, patients with cancer or rheumatoid arthritis, university students, and physicians. Outcomes emphasize the cognitive, social, and cultural influences on beliefs in CAMs, highlighting mechanisms like prior expectations, causal illusions, and health-related judgments. However, limitations include small sample sizes, reliance on self-reports, and theoretical models alongside limited generalizability and potential biases such as recall or selection. The reader can find the studies analyzed in Appendix C.

5.4. The Effects Mediated by Context in Osteopathic and Chiropractic Practices for Musculoskeletal Care

Contextual factors in the therapeutic interaction between patients and healthcare providers encompass a wide range of elements. These factors extend beyond the specific actions of the treatment and include the physical environment, the quality of the relationship with the professional, the patient’s expectations, and the perceived credibility of the therapist. Additionally, rituals, healing cues, and other symbolic elements associated with the treatment process may also play a significant role in the patient’s response [126].

Often, expectations and perceptions of outcomes differ between the healthcare provider and the patient, which can lead to dissatisfaction with conventional care. This dissatisfaction is a key factor driving patients toward CAMs [127]. A patient’s expectations regarding the effectiveness of a therapy can significantly influence their perception of treatment outcomes [9,125]. If a person anticipates improvement, they are more likely to perceive a benefit, even if the treatment is objectively ineffective. Conversely, negative expectations can lead to unfavorable perceptions of outcomes, regardless of the treatment’s objective efficacy. Previous positive experiences can also enhance the response to treatment; for example, individuals who have had success with osteopathic or chiropractic manipulations are more likely to respond favorably to similar treatments in the future [128].

This influence of expectations has been observed by Bialosky [129] inducing positive and negative expectations in a group of patients with low back pain. Subjects who were given positive expectations about the effects of lumbar manipulation experienced a reduction in pain (hypoalgesia) in the treated area. Conversely, those who received negative expectation instructions reported an increase in pain perception (hyperalgesia) in the same region. Interestingly, these changes in pain perception were localized to the region where manipulation was expected to have an effect, with no significant impact on the lower extremities where no expectations were set.

Rituals and ceremonies associated with CAMs can also influence the patient’s perception of treatment effectiveness, contributing to perceived therapeutic effects [116,130]. The “efficacy paradox” illustrates how a complex intervention, such as visceral manipulation or craniosacral mobilization, may have minimal specific effects but a large placebo effect. In contrast, conventional treatment with moderate specific effects but a smaller placebo effect may be perceived as less effective by the patient [130]. The complexity of an intervention often correlates with its perceived effectiveness (Figure 3).

This efficacy paradox has been studied in recent studies. Some patients report significant pain relief after osteopathy and chiropractic sessions primarily based on manipulation. These positive outcomes are short-term and largely attributed to placebo response, mainly driven by personalized care, the therapist–patient relationship, the time dedicated by the practitioner, and the perception of specificity for a particular issue. However, current evidence indicates no significant differences in their application methods, and their use should be prioritized based on patient comfort and preferences [131]. In contrast, therapeutic exercise has strong evidence supporting its effectiveness in improving pain and function in the long term. However, its effects may take longer to manifest and require active patient commitment, which can reduce adherence and the perceived outcomes.

Figure 3. Efficacy paradox: The efficacy paradox focuses on the discrepancies between the results perceived by the patient and the real effectiveness of the intervention. In the case of osteopathy and chiropractic, it focuses on the interaction between the demonstrated specific effect of the technique and the significant influence of the placebo responses, mediated by the effects of non-specific factors and the therapeutic context, such as the complexity of the therapeutic ritual or the expectations generated by the therapist [46,132] Created in BioRender. F, M. (2025) https://BioRender.com/g83d974, accessed on 26 January 2025.

Figure 3. Efficacy paradox: The efficacy paradox focuses on the discrepancies between the results perceived by the patient and the real effectiveness of the intervention. In the case of osteopathy and chiropractic, it focuses on the interaction between the demonstrated specific effect of the technique and the significant influence of the placebo responses, mediated by the effects of non-specific factors and the therapeutic context, such as the complexity of the therapeutic ritual or the expectations generated by the therapist [46,132] Created in BioRender. F, M. (2025) https://BioRender.com/g83d974, accessed on 26 January 2025.

Thus, the positive outcomes perceived by some individuals during the application of certain low-value techniques appear to be more related to the inherent characteristics of the therapeutic process than to the physical intervention itself. These characteristics may include the environment in which the therapy is conducted, the theoretical framework underlying the approach, the evaluation performed in each session, therapeutic touch, and the patient’s active involvement in their treatment [133,134,135]. Therefore, it is crucial to assess the contextual effects that may influence the individual, their condition, the intervention, and the outcome to determine the relevance of a particular intervention in each specific clinical setting [136]. These factors are often present in practices such as osteopathy and chiropractic, and they can lead to confusion on the part of the therapist regarding the actual effects of the applied techniques [95]. While the perceived benefits may be substantial, it is important for practitioners to distinguish between the therapeutic value of contextual factors and the specific efficacy of the techniques themselves.

5.5. Neurobiological Basis of Contextual Effects in Osteopathic and Chiropractic Practices for Musculoskeletal Care

The effects mediated by the context, such as placebo and nocebo effects, are modulated by various neurobiological systems, including opioid, endocannabinoid, and dopaminergic systems, which play an essential role in the modulation of pain and reward pathways [79,137,138]. These systems contribute to the analgesic effects observed in response to treatments, even in the absence of a specific intervention. Furthermore, placebos can influence serotonergic pathways, affecting emotional regulation and mood [137,139]. Placebo effects are also mediated by the interaction between cholecystokinin (CCK) and endogenous opioids, which regulate both positive and negative effects [138,140].

The neural modulation arising from these contextual effects involves a functional connection between several brain regions, such as the dorsolateral prefrontal cortex (CPFDL), the rostral anterior cingulate cortex (rACC), and subcortical regions such as the hypothalamus (HYP), amygdala (AMYG), and periaqueductal gray (PAG), which play a crucial role in placebo-induced analgesia [79,141,142]. During placebo analgesia, decreased neural activity is also observed in pain-associated regions, such as the thalamus and primary somatosensory cortex, and could potentially contribute to a subjective reduction in pain perception [78]. Furthermore, placebo effects also modulate spinal cord activity and descending analgesia pathways, reinforcing the influence of contextual factors on pain relief [143,144]. There are studies suggesting that brain morphology and functional connectivity can predict individual responses to placebo-induced analgesia [145,146]. Conversely, abnormal activation of the hippocampus (Hp) has been linked to nocebo effects, as this region, along with the AMYG, is involved in processing emotions such as anxiety and distress [79].

Differing instructions and expectations regarding the same procedure can alter the nervous system’s response. It has been observed that when people are informed about the therapeutic efficacy of a technique, there is an increase in activity in regions such as the ventral striatum, associated with the reward circuit, and a decrease in activity in secondary somatosensory regions and the right dorsolateral prefrontal cortex. However, this change in activity does not occur when people are told that the technique may be painful or ineffective [147] (Figure 4). These findings suggest that the therapeutic context may have a more significant impact than the intervention itself.

While this evidence marks significant progress in understanding these therapeutic phenomena, research findings remain heterogeneous, and further exploration is needed to better understand the neurobiological mechanisms of these effects [148].

For the analysis of Section 5, the following articles were analyzed, spanning various study types, including narrative reviews, randomized controlled trials, systematic reviews, pilot studies, and meta-epidemiological analyses. They examine placebo and contextual effects in CAMs, with a focus on interventions like osteopathy, chiropractic and treatments for chronic pain and migraines. Populations include patients with chronic and musculoskeletal pain as well as general recipients of CAMs. Key outcomes highlight the role of placebo, nocebo, and contextual factors in shaping treatment perceptions and outcomes, particularly discrepancies in patient expectations. Common limitations include reliance on theoretical frameworks, small sample sizes, lack of control groups, and high heterogeneity in study designs, reducing applicability to specific populations. The reader can find the studies analyzed in Appendix C, Appendix D and Appendix E.

6. Ethical Considerations of the Effects Mediated by Context and Placebo as First-Line Musculoskeletal Therapy

The potential mechanisms underlying the effects of osteopathy and chiropractic in musculoskeletal care remain a matter of debate. On one hand, some studies suggest that specific biological mechanisms may play a role in these therapies, but these mechanisms are poorly understood and require further research [28,76]. On the other hand, most recent evidence highlights the biological implausibility of these CAMs. Even practitioners in these fields exposed the challenges in designing convincing and contextually relevant control interventions, which can significantly influence placebo effects across study groups [132]. Consequently, research findings must be interpreted with caution due to various methodological factors that contribute to a high risk of bias.

Integrating biologically implausible therapies, whose potential mechanisms may rely primarily on placebo effects (contextual and non-specific factors) into healthcare systems raises significant ethical dilemmas. CAMs such as osteopathy and chiropractic may lead to: (1) direct harms (i.e., side effects from cervical manipulation at maximum range of motion [69] or indirect harms (i.e., delaying an effective treatment); (2) emotional or financial harms, particularly for individuals with lower socioeconomic status; (3) wasted clinical resources; and (4) inequities in healthcare delivery.

Although osteopathy and chiropractic have built a substantial body of evidence over the years, clinical trials have consistently failed to demonstrate specific effects for improving various clinical conditions according to the most recent systematic reviews and meta-analyses [29,57,67,149]. For this reason, these therapies are still considered CAMs and have not evolved to conventional medicine. Consequently, their use by health care professionals for musculoskeletal care cannot be recommended. Scientific disciplines must rigorously challenge their own hypotheses and evolve their practices based on evidence. This case should not be an exception.

7. Implication for Clinical Practice

In many countries, these interventions are mandated to be performed by healthcare professionals, inadvertently lending them credibility through association with established musculoskeletal care practices. While it is unlikely that such therapies will disappear, nor is it the intention of this publication to advocate for their elimination, they must be critically evaluated to ensure their safety and efficacy. These practices should not be endorsed or integrated into musculoskeletal care without sufficient scientific validation.

At their current stage of development, most recent reviews and meta-analyses have shown CAMs such as osteopathy and chiropractic to be no better than placebo interventions or natural disease progression. Consequently, their clinical effectiveness is often overestimated, and they cannot be recommended as first-line treatments. This underscores the urgent need for robust, high-quality research to validate their efficacy and mechanisms. Rather than perpetuating a divide between disciplines, fostering constructive dialogue and collaboration between professionals is crucial for advancing integrated healthcare practices. This balanced approach will help ensure that only therapies with demonstrated value for musculoskeletal care are incorporated into mainstream practice, ultimately improving patient outcomes and promoting evidence-based decision-making.

Limitations

This review, while comprehensive, has several limitations that merit acknowledgment. First, as a comprehensive review, the methodology allows for the inclusion of subjective interpretations during the synthesis of evidence. Despite efforts to minimize bias, the absence of a systematic review framework may reduce replicability and introduce selection bias into the literature analyzed.

Second, many of the studies reviewed exhibit significant methodological shortcomings. These include small sample sizes, inadequate control groups, and a reliance on observational designs rather than experimental approaches. Together, these factors weaken the robustness of the conclusions and hinder the generalization of findings to broader clinical contexts. The substantial heterogeneity in study designs and varying levels of methodological quality further exacerbate these challenges.

Third, although the focus of this review is the use of CAMs in musculoskeletal care—particularly osteopathy and chiropractic—some conjectures are derived from studies investigating different techniques or clinical scenarios. These findings may not always be directly transferable to the specific domain of interest, thereby limiting their applicability.

Fourth, certain articles reviewed on biological and psychological mechanisms are not specifically oriented toward CAMs, reducing their relevance and generalizability to this field.

Five, it is likely that the changes observed by osteopaths and chiropractors in their patients’ symptoms are due to unconscious long-term effects, such as placebo responses and non-specific factors, rather than specific effects of the interventions. These effects have not been studied in the long term, and there is no known evidence on the medium- and long-term impacts of these therapies.

Finally, the limited and methodologically diverse body of literature addressing the biological plausibility and potential mechanisms of osteopathy and chiropractic in musculoskeletal care has created theoretical gaps. These gaps necessitated reliance on broader or indirectly related studies to propose hypotheses, which may introduce additional uncertainty.

These limitations highlight the urgent need for future research employing rigorous and standardized methodologies. Well-designed randomized controlled trials, larger and more representative sample sizes, and consistent reporting standards are essential to address the gaps identified in the existing literature. Such efforts will contribute to a clearer understanding of CAMs’ role in musculoskeletal care and ensure that clinical practice remains grounded in scientifically validated principles.

8. Conclusions and Future Perspectives

The growth of musculoskeletal care as a clinical field reveals a dark side, or perhaps a gray area, characterized by the increasing adoption of therapies lacking robust scientific evidence, which undermines the legitimacy of the discipline. Scientific knowledge is essential for advancing healthcare; however, it is inherently limited. The absence of evidence does not equate to falsity, and what is accepted as valid today may be refuted tomorrow. Thus, it is crucial to distinguish between the veracity of a claim and the quality of the available evidence. Nevertheless, reliance on methodologies that lack scientific rigor, even when they occasionally yield promising results, is neither prudent nor ethical.

In many countries, osteopathy and chiropractic care are delivered by healthcare professionals, a fact that—combined with their association with validated musculoskeletal care practices—inadvertently lends these therapies credibility through authority bias. However, these interventions often rely on theoretical models and mechanisms of action rooted in questionable biological plausibility. Diagnoses such as “somatic dysfunctions” or “vertebral subluxations” are inconsistent with established scientific knowledge. Conducting research based on these concepts poses significant challenges to validating the treatments proposed by these therapies, especially when they are founded on implausible anatomical and physiological beliefs.

Studies evaluating the clinical effects of these interventions are frequently marred by significant biases, including small sample sizes, the absence of standardized control groups, the use of inadequate assessment tools, and a reliance on observational designs. Furthermore, the lack of proper planning for controls or placebos can lead to erroneous interpretations by introducing contextual and non-specific factors that alter the dynamics between participants and therapists during research.

Key contextual and non-specific factors influencing outcomes include participants’ expectations, amplified therapeutic rituals in the research setting, prior experiences with similar interventions, interactions with the research team, and variables such as the number, type, and timing of manual interventions. Additional influences include placebo effects, regression to the mean, and the natural history of the condition. These limitations hinder the generalizability of findings and reduce confidence in conclusions regarding the clinical effectiveness of these interventions.

Based on the current body of evidence, neither osteopathy nor chiropractic care can be recommended as first-line treatments for musculoskeletal conditions. Nonetheless, these practices are likely to remain part of clinical care due to cultural, historical, political, and patient preference factors. Therefore, it is imperative that these therapies undergo critical evaluation and are integrated into healthcare only when their safety and clinical efficacy are supported by rigorous scientific validation. By doing so, healthcare professionals can uphold their legitimacy, improve therapeutic outcomes, and foster informed decision-making.

Future research should prioritize addressing the limitations of the existing evidence base. This involves designing well-structured randomized controlled trials with larger, representative sample sizes and adequately planned control groups. Additionally, studies should incorporate approaches that consider contextual and non-specific factors, which, despite being often overlooked, appear to significantly impact clinical outcomes. Understanding these factors will contribute to a more accurate interpretation of the specific effects of osteopathic and chiropractic interventions. Furthermore, exploring advanced technologies—such as neurophysiological data analysis and its correlation with clinical outcomes—can provide greater precision in understanding the mechanisms of action of these therapies. Longitudinal studies are also essential to assess the long-term effects of these interventions, especially when integrated with evaluations of contextual and non-specific influences, which have been underexplored to date.

Finally, implementing evidence-based practices should be a priority, requiring healthcare professionals to actively stay informed and critically assess the methodological quality of published studies. To this end, we advocate for fostering a spirit of transdisciplinary and interdisciplinary collaboration among healthcare professionals and researchers to enhance methodological approaches and generate new evidence that optimizes clinical practice. Through this collective effort, the field of musculoskeletal healthcare can advance, promoting patient safety and delivering more effective treatments grounded in the best available scientific evidence.