Additional Effect of Extracorporeal Shockwave Therapy with Lidocaine Injection on Clinical and MRI Findings in Frozen Shoulder: A Prospective, Randomized, Double-Blinded, Placebo-Controlled Trial

Introduction: Frozen shoulder is a very common musculoskeletal condition and the evidence related to the additional effects of extracorporeal shockwave therapy (ESWT) with intra-articular (IA) lidocaine injection in individuals with frozen shoulder is rare. Therefore, this study aims to compare and investigate the additional effects of extracorporeal shockwave therapy (ESWT) with intra-articular (IA) lidocaine injection in a frozen shoulder. Methods: Sixty eligible participants with frozen shoulder were included and the active group (n = 30, age 52.12 ± 5.2 years) received a lidocaine injection (1% lidocaine (Xylocaine) and 2cc (80 mg) methylprednisolone acetate) with active ESWT (3.5 bar air pressure and 2000 pulses with an energy flux density (EFD) ¼ 0.16 mJ/mm²) three sessions a week for 4 weeks. The placebo group (n = 30, age 53.56 ± 5.5 years) received lidocaine injection with placebo treatment (a special head that blocked the shock waves) three sessions a week for 4 weeks. Both groups received progressive resistance exercises (PRE) to the shoulder muscles. The primary outcome was pain intensity, measured with the visual analogue scale. The other outcome measures were the thickness of the coracohumeral ligament (CHL) measured by magnetic resonance imaging (MRI), abduction, and lateral rotation range of motion (ROM), functional disability, kinesiophobia, depression status, and quality of life. Participants were assessed at baseline, after 4 weeks, 8 weeks, and at 6-month follow-up. Results: The post-intervention at 4 weeks showed an improvement of 2.0 (CI 95% 1.71–2.28) in the active group compared to the placebo group. Similar effects were noted after 8 weeks (2.2) (CI 95% 1.91–2.48) and at the 6-month (1.9) (CI 95% 1.61–2.18) follow-up. Similar improvements were also found in the thickness of the CHL ligament (0.6) (CI 95% 0.46–0.73), abduction and lateral rotation (ROM) (– 23.6) (CI 95% – 27.47 to -19.72), (- 18.10) (CI 95% – 19.72 to – 16.47), functional disability (16.2) (CI 95% 14.85–17.54), kinesiophobia (11.0 (CI 95% 10.21–11.98), depression status (4.4) (CI 95% 4.03–4.76) and quality of life (0.9) (CI 95% 0.79–1.00) (p = 0.001) at the 6-month follow-up period, where mean estimates and their confidence intervals all included worthwhile effects. There were no adverse reactions or side effects noted in either the active or placebo groups during and after the treatment. Conclusions: The study concluded that the addition of extracorporeal shockwave therapy after intra-articular lidocaine injection improves pain, functional disability, range of motion, kinesiophobia, depression status, and quality of life in people with frozen shoulder. Trial Registration: https://ctri.nic.in, identifier; CTRI/2020/04/024834 prospectively registered on 24/04/2020.