Radial ESWT combined with a specific rehabilitation program (rESWT+RP) is more effective than sham rESWT+RP for acute hamstring muscle complex injury type 3b: a randomized, controlled trial

Abstract

Introduction: Acute type 3b injuries of the hamstring muscle complex (HMC) are prevalent in sports, often lead to prolonged recovery, and demonstrate a high recurrence. Conservative rehabilitation is standard, and adjunct therapies such as radial extracorporeal shock wave therapy (rESWT) may offer additional benefits.

Sources of data: This randomized controlled trial, with blinding of patients and assessors, included 36 semi-professional athletes with ultrasound-confirmed acute type 3b HMC injuries. Participants received either real or sham rESWT in combination with an 8-week structured rehabilitation program. The primary outcome was time to return to sport; secondary outcomes included post-treatment muscle strength, patient satisfaction, and re-injury rate.

Areas of agreement: Progressive rehabilitation is effective for muscle injuries. rESWT is a safe, non-invasive modality with high therapeutic potential in musculoskeletal conditions.

Areas of controversy: Questions remain regarding the ideal rESWT protocol for acute muscle injuries, including optimal dosing, frequency, and timing relative to injury onset.

Growing points: The addition of rESWT resulted in a statistically significant reduction in return-to-sport time [25.4 ± 3.5 (mean ± SD) days with rESWT vs 28.3 ± 4.5 days with sham rESWT; P = .037]. In elite and semi-professional athletes, even modest reductions in downtime can carry meaningful performance and economic benefits. Furthermore, only the rESWT group avoided strength deficits in the previously injured leg, suggesting improved functional recovery.

Areas timely for developing research: Future studies should explore the comparative effectiveness of individualized versus standardized rESWT protocols and investigate its broader applicability across sports disciplines and levels of play.

Keywords: ESWT; RCT; extracorporeal shock wave therapy; hamstring; rESWT; radial extracorporeal shock wave therapy; randomized controlled trial; rehabilitation; structural muscle injury.

Figure 1

Working principle of the handpiece of a pneumatic, rESWT device (modified from [9]). Compressed air (1) is used to fire a projectile (2) within a guiding tube (3) on a metal applicator (4) that is placed on the patient’s skin. The projectile generates stress waves in the metal applicator that transmit pressure waves (rESWs) into tissue (5).

Figure 2

Flow of patients through the trial according to the CONSORT statement [35].

Figure 3

Individual time course of the patients in this trial. The horizontally arranged numbers are the days in the study (Day 1, randomization). The vertically arranged numbers represent the consecutive order of the patients according to the individual time to return to sport in the rESWT + RP group (patients 1–18) and the sham rESWT + RP group (patients 19–36) of the mITT population. For each patient the durations of Phase 1 (red), Phase 2 (yellow) and Phase 3 (blue) as well as the day of return to sport (green) are indicated, as well as all rESWT treatments (closed dots) or sham-rESWT treatments (open dots). The black rectangle in the line of patient 24 indicates the imputed missing value.

Figure 4

Duration of Phase 3 (functional phase) as a function of the duration of Phase 2 (subacute/regeneration phase) of all patients in this trial (except of patient 24 in the sham-rESWT + RP group who was lost during Phase III). The results of linear regression analysis are indicated.

Figure 5

Individual data and group-specific mean ± SD of the isometric knee flexor strength post-treatment of the injured leg (I) and the non-injured leg (NI) of the patients in the rESWT + PR group (green dots) and the patients in the sham-rESWT + PR group (red dots). Results of Fisher’s LSD post hoc test for pairwise comparisons are indicated.