Manual Therapy: Efficacy, Mechanisms, and Duration Remain Uncertain

Manual therapy is central to the professional identity of physical therapy. Its hands-on approach differentiates it from supervised exercise sessions, is frequently requested by patients, and is regarded by many clinicians as a reliable clinical tool. After a recent conversation with Dr. Chad Cook, manual therapy remains the core of the physical therapy professional identity.  However, the current literature highlights that manual therapy remains one of the most misunderstood interventions in musculoskeletal medicine. This misunderstanding does not come from a lack of validity; evidence indicates probable efficacy in specific contexts and for limited durations. Rather, the lack of clarity is from insufficient inquiry into its mechanisms, optimal use conditions, and the quality of the evidence supporting its widespread application.

These five papers address the complexities of manual therapy from multiple perspectives and reach a similar conclusion: manual therapy demonstrates a genuine clinical effect, yet its mechanisms are poorly understood, the supporting evidence base is methodologically limited, and its public representation is inadequate by educational standards. This situation does not create a conflict, but rather provides a framework for improvement. The profession now has sufficient information to develop a stronger, more defensible approach contingent upon collective action.​

What the Clinical Evidence Actually Supports

Smith and colleagues conducted a narrative review in American Family Physician, synthesizing evidence on manipulative therapies for various conditions. For low back pain, spinal manipulation yields clinically and statistically significant short-term improvements in pain and function. However, when compared to exercise, analgesics, or standard physical therapy, its advantage is negligible, performing similarly to these alternatives. In cases of neck pain, cervical manipulation and mobilization provide small, short-term improvements, but the authors emphasize the importance of risk assessment due to rare yet serious adverse events such as vertebrobasilar injury. This necessitates more rigorous clinical reasoning than is typically applied. For migraines, manipulative therapy demonstrates short-term effects comparable to amitriptyline, a finding that warrants greater attention. In pediatric populations, the evidence does not support the use of manipulative therapy for most conditions.

Collectively, the Smith review characterizes manual therapy as having a limited but objective clinical role, primarily in short-term symptom management for spinal pain and comparable to other first-line conservative treatments. This position remains defensible only when clinical application aligns with the supporting evidence.

The Mechanism Problem

While the clinical evidence for manipulation is modest yet credible, the underlying mechanisms remain complex and unresolved. Keter and colleagues conducted a living review of systematic, narrative, and scoping reviews, revealing that manual therapy elicits responses across neurological, neurovascular, neuroimmune, neuromuscular, neuroendocrine, and neurochemical systems. Observed changes include altered sympathetic activity, cortical activation patterns on fMRI, inflammatory marker levels, muscle recruitment, and cortisol fluctuations. These represent measurable physiological responses at peripheral, spinal, and supraspinal levels, rather than placebo effects.

The hierarchy of evidence quality for proposed mechanisms warrants careful consideration. Moderate-quality reviews support neurovascular, neurological, and neurochemical changes. In contrast, low-quality reviews underpin neuroimmune, neuromuscular, and neuroendocrine changes. Critically low-quality reviews support biomechanical explanations, such as joint-specific or tissue-level mechanisms frequently cited by practitioners. These commonly used clinical narratives, including restoring segmental mobility or decompressing a disc, currently have the weakest evidentiary support.

The authors emphasize that current mechanistic findings do not fully explain the clinical efficacy of manual therapy or identify which mechanisms drive patient outcomes. Although such gaps between biological signals and clinical explanations are common in medicine, physical therapy should prioritize addressing this uncertainty rather than relying on oversimplified biomechanical explanations.

The Evidence Base Has a Design Problem

Grenier and Thiel's recent scoping review addresses methodological limitations in manual therapy research. The prevalent trial design, which compares usual care to usual care plus manual therapy, is inherently flawed. This approach conflates the specific effects of manipulation with nonspecific effects such as increased contact, attention, patient expectations, and therapeutic alliance. Although 53.7% of trials report short-term benefits, these effects diminish substantially at medium and long-term follow-up, raising concerns about whether current trial designs accurately measure the intervention's true efficacy.

The most significant finding from the review is the quality gradient: studies with lower methodological rigor are substantially more likely to report positive outcomes, with 85% of low-quality trials showing benefit compared to 50% of medium- and high-quality trials. This pattern suggests that methodological shortcomings inflate reported efficacy. Among sham-controlled trials, which best isolate specific effects, three out of four found no significant added benefit of manual therapy. The fourth trial used a sham involving manipulation of a different cervical segment, which may not constitute a true sham control.

None of this means that manipulation does not work. It means the literature as currently constructed is not capable of telling us precisely how much it works, for whom, and by what mechanism. The profession's instinct has often been to defend the intervention against critique rather than improve the evidence base. That instinct is understandable. It is also professionally costly.

The YouTube Problem Is Also a Profession Problem

Arslan and colleagues examined YouTube videos claiming to demonstrate lumbar spinal manipulation techniques and found that the average video met only 2.40 out of 6 criteria on the AAOMPT Manipulation Definition Scale. Merely 2% of videos satisfied all criteria, with contraindication information present in 6% and clinical prediction rules mentioned in 8%. This issue extends beyond social media and reflects a broader professional challenge. Many of these videos are produced by practicing clinicians and educators, and their content represents the profession's standards for public instruction on a technique associated with documented adverse events. The quality is worth sitting with. The profession with the strongest public communication strategy around manipulation is not producing better instructional content. It is producing more watchable content. Physical therapy has both a quality problem and a reach problem in this space, and the two are not unrelated. If the profession is not producing accurate, thorough, widely viewed content about its own techniques, someone else will fill that gap, and the evidence suggests they already are.

What About Knee Osteoarthritis

Feng and colleagues' overview of systematic reviews on manual therapy for knee osteoarthritis reveals a pattern consistent with the broader manual therapy literature: the intervention demonstrates a positive clinical signal, yet the supporting evidence is of poor quality. Of the eleven systematic reviews included, nine were rated as critically low quality and two as low quality according to AMSTAR-2, with none rated moderate or high. A re-meta-analysis indicated a 15% higher total effective rate for manual therapy compared to control, with no severe adverse events reported. This clinically meaningful effect size, however, is based on methodologically unreliable evidence, a characterization applicable to much of the current literature.

The Coherent Picture

Synthesizing findings from these five papers, manual therapy emerges as a legitimate intervention with measurable physiological effects and a demonstrable clinical signal for short-term pain management in spinal and certain peripheral joint conditions. However, current evidence does not sufficiently explain its mechanisms or justify the level of confidence with which it is frequently applied, taught, and defended.

The biomechanical mechanisms most commonly cited by clinicians are supported by the weakest evidence. The trial designs showing the most favorable results are also the least effective at isolating the intervention's specific effects. Public-facing instructional content does not meet the profession's standards, and effect sizes, when compared to active controls over meaningful timeframes, are modest.

These limitations do not justify abandoning manual therapy, but rather call for a more critical and evidence-based approach. This includes teaching manual therapy within a mechanistic framework that recognizes neurophysiological complexity, designing and advocating for higher-quality comparative trials, and producing improved educational content for both public and professional audiences. It also requires accepting that a technique can be clinically valuable and professionally legitimate, even if its mechanisms are not fully understood.

A profession that acknowledges uncertainty while maintaining clinical rigor is more credible than one that overstates its claims. The current literature supports this more measured stance.

Citations

Monday

Smith, M. S., Olivas, J., & Smith, K. (2019). Manipulative therapies: What works. American Family Physician, 99(4), 248-252.

Tuesday

Arslan, S., Dinc, E., & Arslan, T. (2023). Are YouTube videos claiming to describe lumbar spinal manipulation techniques adequate? Journal of Manual & Manipulative Therapy, 31(6), 449-455. https://doi.org/10.1080/10669817.2023.2244398

Wednesday

Feng, T., Wang, X., Jin, Z., Qin, X., Sun, C., Qi, B., Zhang, Y., Zhu, L., & Wei, X. (2023). Effectiveness and safety of manual therapy for knee osteoarthritis: An overview of systematic reviews and meta-analyses. Frontiers in Public Health, 11, 1081238. https://doi.org/10.3389/fpubh.2023.1081238

Thursday

Keter, D. L., Bialosky, J. E., Brochetti, K., Courtney, C. A., Funabashi, M., Karas, S., Learman, K., & Cook, C. E. (2025). The mechanisms of manual therapy: A living review of systematic, narrative, and scoping reviews. PLOS ONE, 20(3), e0319586. https://doi.org/10.1371/journal.pone.0319586

Friday

Grenier, J.-P., & Thiel, A. (2025). Evaluating manual therapy in musculoskeletal pain: Why certain trial designs may overestimate effectiveness: A scoping review. European Journal of Pain, 29, e70150. https://doi.org/10.1002/ejp.70150

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Weekly MSK Literature Review | Alex Bendersky, DPT