Focused Extracorporeal Shock Wave Therapy Versus Therapeutic Ultrasound as Adjuncts to Exercise‐Based Rehabilitation for Functional Limitation in Ankylosing Spondylitis: An Assessor‐Blinded Randomized Comparative Trial

BACKGROUND: The comparative effectiveness of adjunctive physical modalities alongside exercise for ankylosing spondylitis (AS) remains inadequately evaluated. OBJECTIVE: To compare the relative association of focused extracorporeal shock wave therapy (ESWT) versus therapeutic ultrasound, both added to identical exercise-based rehabilitation, with long-term functional outcomes in AS. METHODS: This assessor-blinded randomized comparative trial (conducted March 2024-August 2025) evaluated 106 AS patients with chronic lumbar stiffness (90 completed 12-month follow-up). Participants received either focused ESWT (weekly × 4 weeks, n = 45) or ultrasound (3 × /week × 4 weeks, n = 45), alongside identical 12-week supervised exercise and stable pharmacotherapy. The primary outcome was functional capacity (BASFI). Secondary outcomes included disease activity (BASDAI), pain, spinal mobility (modified Schober) and disability (DFI). This trial was not prospectively registered and lacked an exercise-only control arm; therefore, findings should be interpreted as exploratory. RESULTS: Both groups improved significantly across all outcomes (p < 0.001). At 12 months, the ESWT group was associated with lower BASFI scores (2.2 ± 1.8 vs. 3.7 ± 2.3; p = 0.001; Cohen's d = 0.72) and lower disability (DFI: p = 0.003; d = 0.63) than the ultrasound group. Lumbar mobility differed nominally (p = 0.030) but did not survive correction for multiple secondary comparisons. No significant between-group differences were observed for BASDAI (p = 0.424) or pain (p = 0.284). CONCLUSIONS: When added to identical exercise and pharmacotherapy, focused ESWT was associated with greater long-term functional improvement compared with therapeutic ultrasound. However, in the absence of an exercise-only control, the incremental benefit of either modality over exercise alone cannot be determined. Given the lack of prospective registration and other methodological limitations, these preliminary findings require confirmation through properly registered trials before any clinical recommendations can be made.