Supervised Physiotherapy Versus Home-Based Exercise in Lateral Elbow Tendinopathy: The Mediating Role of Adherence and Moderation by Baseline Severity

Introduction. To compare supervised physiotherapy and structured minimally supervised home-based rehabilitation in patients with lateral elbow tendinopathy (LET) and to determine whether treatment adherence mediates clinical outcomes and whether baseline symptom severity modifies treatment response. Materials and Methods. In this prospective assessor-blinded randomized controlled trial, 48 participants with clinically diagnosed LET were randomly assigned to supervised physiotherapy (n=24) or minimally supervised home-based rehabilitation (n=24). Both interventions were delivered for six weeks and included eccentric loading, stretching, and progressive strengthening exercises. Pain intensity was assessed using the Visual Analog Scale (VAS), upper-limb function using the Patient-Rated Tennis Elbow Evaluation (PRTEE), and pain-free grip strength using a hand dynamometer. Assessments were performed at baseline, Week 6, and Week 18. Adherence was monitored prospectively. Exploratory mediation and moderation analyses were conducted. Results. Both groups demonstrated significant improvements in pain, function, and grip strength over time (p<0.001). However, supervised physiotherapy produced significantly greater improvements in VAS pain (Group×Time interaction, p=0.003), PRTEE score (p=0.002), and grip strength (p=0.001). At Week 18, VAS pain decreased from 72.4±10.6 mm to 16.9±10.8 mm in the supervised group and from 71.7±11.2 mm to 31.8±14.5 mm in the home-based group, corresponding to a between-group difference of 14.9 mm (95% CI 7.2-22.6). PRTEE scores improved from 61.8±11.9 to 14.2±9.6 and from 60.7±12.5 to 27.9±12.4, respectively, with a between-group difference of 13.7 points (95% CI 6.4-21.0). Grip strength increased from 20.3±6.1 kg to 36.7±6.8 kg in the supervised group and from 20.8±5.9 kg to 30.2±6.7 kg in the home-based group, with a between-group difference of 6.5 kg (95% CI 2.8-10.2). Adherence was significantly higher in the supervised group (94.2±5.6%) than in the home-based group (82.8±11.4%; p<0.001). Mediation analyses demonstrated significant indirect effects through adherence for VAS improvement (β=0.18, 95% CI 0.05-0.33, p=0.008), PRTEE improvement (β=0.16, 95% CI 0.04-0.30, p=0.011), and grip-strength recovery (β=0.14, 95% CI 0.03-0.27, p=0.017), accounting for 31%, 24%, and 37% of total treatment effects, respectively. Moderation analyses suggested that greater baseline pain severity was associated with larger benefits from supervised rehabilitation (interaction β=0.29, 95% CI 0.08-0.50, p=0.006). Conclusions. Both rehabilitation approaches were effective for LET management. Supervised physiotherapy resulted in greater improvements in pain, function, grip strength, and adherence. Adherence partially mediated treatment-related improvements, whereas higher baseline pain severity appeared to enhance responsiveness to supervised rehabilitation. Supervised rehabilitation may therefore be particularly beneficial for patients presenting with greater symptom burden.