Therapeuticeffectoffocused-extracorporealshockwavetherapyonmuscularandadjacenttissuestiffnessandpainchangesinmyofascialpainsyndrome:Arandomizedcontrolledtrialstudy

Myofascial pain syndrome (MPS) is a common condition among office workers who spend long hours in fixed postures, particularly those working with computers. This so-called "office syndrome" leads to neck pain, muscle stiffness, and reduced work performance. The upper trapezius muscle is frequently affected, developing painful trigger points that cause both local and referred pain. While various treatments exist—including exercise, ergonomic changes, ultrasound, and manual therapy—newer approaches like extracorporeal shock wave therapy (ESWT) have gained attention.

Focused ESWT (fESWT) delivers concentrated, penetrating shock waves that may target deeper tissues more precisely than radial ESWT. However, evidence for fESWT's effects on actual muscle stiffness (not just pain) remained limited. This study aimed to fill that gap by examining whether fESWT could reduce tissue stiffness, pain, and functional disability in office workers with upper trapezius MPS.

The researchers conducted a double-blind randomized controlled trial with 64 office workers (average age 31 years) who had active myofascial trigger points in one side of their upper trapezius. Participants were randomly assigned to either a real fESWT group or a sham-fESWT control group, with 32 people in each group. The real treatment used a Swiss DolorClast device delivering 1,200 shocks at 4 Hz frequency to the trigger point, with energy density ranging from 0.1 to 0.232 mJ/mm² adjusted to each person's pain tolerance. The sham group received only 300 shocks at much lower energy (0.03 mJ/mm²) with the device positioned near—but not directly on—the trigger point, a protocol previously shown to have no therapeutic effect.

Both groups received four weekly sessions. Three different examiners, all blinded to group assignments, measured outcomes: tissue stiffness using ultrasound shear-wave elastography (shear modulus in kPa), pain intensity on a 0–10 cm visual analogue scale (VAS), and functional disability using the Neck Disability Index (NDI). Measurements were taken at baseline, immediately after each treatment, at two weeks, and at four weeks.

The fESWT group showed significant benefits compared to sham for both tissue stiffness and pain. Shear modulus at the trigger point decreased by 6.1 kPa immediately after the first treatment (p = 0.009), indicating rapid reduction in tissue stiffness. By four weeks, stiffness in the lower aponeurosis (deep fascia region) also decreased by 5.3 kPa (p = 0.004). The sham group, in contrast, actually showed increased stiffness in the upper aponeurosis at two weeks (p = 0.001).

Pain scores (VAS) decreased significantly at all time points in the fESWT group (p < 0.05), while the sham group only showed pain reduction during the final two weeks. Notably, before each session, both groups still had similar baseline pain levels—suggesting fESWT's pain relief was immediate rather than cumulative. The sham group had higher pain scores than the fESWT group after treatments 1–3. For functional disability, both groups improved after four sessions [fESWT: effect size d = 2.49, p < 0.001; sham: d = 2.30, p < 0.001], but there was no significant difference between groups.

No correlation was found between muscle pain and intramuscular stiffness at baseline.

This study provides evidence that focused-extracorporeal shockwave therapy can rapidly reduce both pain and objective tissue stiffness in myofascial pain syndrome of the upper trapezius. The immediate effect on trigger point stiffness after a single session is particularly notable for clinical practice, as it could enhance patient satisfaction and encourage treatment adherence. The delayed reduction in lower aponeurosis stiffness suggests fESWT may also modulate deeper fascial tissues over time, possibly through effects on the spinal accessory nerve pathway. However, the study also revealed that sham treatment produced meaningful pain reduction and functional improvement in later weeks, highlighting the substantial placebo and psychological components in pain perception.

For clinicians, this means fESWT is a viable option for MPS, but expectations should be managed realistically. The lack of difference in neck disability between groups suggests that perceived pain relief—whether from active or sham treatment—can drive functional improvements. Patients should know that while fESWT offers genuine mechanical benefits for tissue stiffness, their own expectations and the therapeutic encounter also play important roles in recovery. Future research needs to determine optimal treatment frequency (some studies use 2–3 times per week versus once weekly here) and whether combining fESWT with exercise and ergonomic interventions would enhance outcomes.