Trigger Point or Fibrous Adhesion? How the Same Tender Spot Can Be Both

Ask three different providers to feel the same tender knot in your shoulder and you might get three different answers: it's a trigger point, it's adhesion, it's just tight muscle. Patients are usually left assuming these are competing diagnoses - pick one - when the more accurate picture, backed by where the research has actually moved in the last year, is that the same spot can genuinely be both at once, and that's often exactly why it isn't resolving.

Trigger point: neurologically excited tissue

A trigger point is a localized knot of muscle fibers held in continuous contraction because of nervous system overactivity, producing tenderness and pain that frequently refers to other areas of the body. The classic explanation, formalized by Janet Travell and David Simons and later expanded by Gerwin, Dommerholt, and Shah, is the "integrated hypothesis": dysfunctional motor endplates release excess acetylcholine, sustaining a small cluster of muscle fibers in contracture, which compresses local capillaries, starves the tissue of oxygen, and triggers a release of sensitizing, inflammatory chemicals. Later work by Jay Shah and colleagues gave this real biochemical support - using microdialysis, they measured significantly lower pH and elevated substance P, CGRP, bradykinin, and inflammatory markers like TNF-alpha and IL-1beta at active trigger points compared to nearby normal tissue.

What's genuinely unsettled is whether a trigger point is also a distinct, physical lesion you could find on a biopsy. A 2015 critique in Rheumatology by Quintner, Bove, and Cohen argued no such lesion has ever been reliably demonstrated, and that the phenomenon is better explained by ordinary nerve sensitization. A 2025 study that actually biopsied clinically-identified trigger points, published in Scientific Reports, found something that surprised even researchers expecting to find the classic "contraction knot": none were present. Instead, the tissue showed muscle fiber atrophy, fibrofatty replacement, and disorganized collagen and fibroblast activity - the signature of tissue remodeling, not a discrete neuromuscular lesion.

Fibrous adhesion: collagen "glue" in muscle

Fibrous adhesion is a structural problem rather than a neurological one. It's dense, disorganized collagen that binds muscle fibers together and to the surrounding tissue, restricting the normal glide between tissue layers. That loss of glide is what shows up clinically as reduced flexibility and range of motion - and because rigid, non-contractile collagen is substituting for tissue that should be transmitting force, adhesion can leave the muscle mechanically weaker as well, not just stiffer.

The mechanism is well described in the muscle fibrosis literature: when collagen production outpaces its normal breakdown - typically after an injury, a period of immobilization, repetitive strain, or ongoing low-grade inflammation - fibroblasts and resident fibro-adipogenic progenitor cells lay down excess extracellular matrix, driven substantially by TGF-beta signaling. Left alone, that restriction tends to persist and can worsen over time, which is a large part of why we've written before about how aging cells actively worsen adhesion, and why it may be the single most common, and most treatable, pathology underlying a lot of chronic musculoskeletal pain.

How the same spot ends up being both

This is where the two pictures collide, and it's a genuinely active, still-unfolding area of research rather than an old settled fact. A 2025 review in Frontiers in Pain Research proposes that fibrotic, densified fascia isn't just a bystander in myofascial pain - it's a co-driver. When the ground substance between fascial layers thickens and loses its normal slipperiness, it stops absorbing movement the way it should, and that abnormal mechanical tension gets transmitted directly onto the sensory nerve endings woven through the tissue. That's a plausible, mechanical route by which an area of adhesion generates the same referred pain and tenderness we call a trigger point.

The 2025 biopsy findings mentioned above point the same direction from the opposite side: a spot that starts out purely as neurologically-driven irritability sits in exactly the kind of chronic, low-grade inflammatory environment - lower pH, elevated inflammatory signaling - that also happens to be what drives fibrotic collagen deposition in the first place. A longstanding trigger point may, over time, accumulate genuine structural adhesion in the same tissue, and a longstanding area of adhesion may generate enough abnormal mechanical strain to keep the local nerve supply irritated. Neither model excludes the other; in a chronic case, they are plausibly reinforcing each other in the same few square centimeters of tissue.

Why this matters more than the label

Physical exam findings for both conditions have real, documented limits. A 2017 meta-analysis in the Clinical Journal of Pain, pooling data across 363 patients, found only fair-to-moderate agreement between examiners palpating for trigger points - a pooled kappa around 0.45. Tenderness itself was reasonably reproducible, but the taut band and twitch response that are supposed to confirm the diagnosis were considerably less so. Manual assessment of adhesion specifically hasn't been studied nearly as rigorously, but there's no reason to expect it fares dramatically better by feel alone.

Practically, this argues against treating "is this a trigger point or is it adhesion" as a question with one right answer, especially in a case that's been present for months rather than weeks. It's usually more useful to ask whether both the structural piece - restricted glide, a genuinely dense or fibrotic feel to the tissue - and the neurological piece - a taut band, reproducible referred pain on compression - are present together, because treatment aimed at only one side of that combination is a common reason results stall.

That's the logic behind combining manual adhesion release with shockwave therapy. A 2025 scoping review of extracorporeal shockwave for myofascial pain found moderate-to-good efficacy across the studies it pooled, with proposed mechanisms - improved local blood flow, mechanotransduction effects on the tissue, and reduction of the same inflammatory substances Shah's group measured at active trigger points - that plausibly address both the structural and neurological side of the same spot at once, even though the review's own authors were candid that the underlying studies are still too inconsistent in method to call this settled science. Manual and instrument-assisted soft tissue techniques take a more direct route at the structural side: a 2017 review in the Journal of Exercise Rehabilitation describes how instrument-assisted mobilization appears to increase local fibroblast activity and encourage more organized collagen realignment, based mostly on animal-model evidence alongside human studies showing acute improvements in range of motion - the review's own authors note that more rigorous human research is still needed, an honest caveat that applies to most of this field.

If a sore spot in your shoulder, hip, or back has been sticking around for months and nothing quite fits - it's tender and refers pain like a trigger point, but it also feels genuinely bound down and doesn't loosen with the usual stretching - that combination is worth having assessed directly rather than guessed at. Book an exam and we'll find out what's actually going on in the tissue, not just what it's called.

Sources

• Travell, J.G. & Simons, D.G. - foundational "integrated hypothesis" of trigger point formation, later expanded by Gerwin, Dommerholt, and Shah.
• Jay Shah and colleagues - microdialysis studies measuring elevated substance P, CGRP, bradykinin, and inflammatory markers at active trigger points.
• Quintner, J.L., Bove, G.M., & Cohen, M.L. (2015). Rheumatology - critique of the trigger-point-as-lesion model.
• 2025 biopsy study of clinically-identified trigger points, published in Scientific Reports.
• 2025 review in Frontiers in Pain Research on fibrotic, densified fascia as a mechanical driver of myofascial pain.
• 2017 meta-analysis in the Clinical Journal of Pain (363 patients) on inter-examiner reliability of trigger-point palpation.
• 2025 scoping review of extracorporeal shockwave therapy for myofascial pain.
• 2017 review in the Journal of Exercise Rehabilitation on instrument-assisted soft tissue mobilization.