Transcutaneous Electrical Nerve Stimulation (TENS) Versus Microcurrent Electrical Neuromuscular Stimulation (MENS)...

Background/Objective: Partial-thickness rotator cuff tears represent a distinct, highly prevalent clinical entity governed by a multifactorial continuum of intrinsic senescence and extrinsic biomechanical overload, rather than an oversimplified acute traumatic versus degenerative dichotomy. While conservative management centered on kinesiotherapy is primary, Transcutaneous Electrical Nerve Stimulation (TENS) and Microcurrent Electrical Neuromuscular Stimulation (MENS) are widely utilized as adjunctive electrophysical modalities. However, empirical trials directly comparing their long-term therapeutic longevity and structural stability remain scarce. This prospective, randomized, participant- and outcome assessor-blinded clinical trial evaluated the 12-month effectiveness of combining structured kinesiotherapy with either TENS or MENS in patients with partial-thickness rotator cuff tears. Methods: Of 47 candidates screened via standardized physical provocation tests and musculoskeletal ultrasound, 5 were excluded prior to treatment allocation. Exactly 42 eligible patients (n = 42; 22 males, 20 females; mean age: 46.71 ± 12.24 years) were formally enrolled and randomized (1:1) to receive 15 supervised sessions of either conventional sensory TENS (n = 21; 100 Hz, 10-15 mA) or subsensory MENS (n = 21; 50 Hz, 100 μA) alongside an identical kinesiotherapy program. Longitudinal evaluations were conducted at baseline, 1, 3, 6, and 12 months post-treatment, achieving a 100% participant retention rate (n = 42). Clinical outcomes comprised the Shoulder Pain and Disability Index (SPADI), an 11-point Numeric Rating Scale (NRS) for pain, and the EuroQoL 5-Dimension Questionnaire (EQ-5D). Structural tear dimensions were monitored via serial ultrasonography. Longitudinal data were analyzed using two-way repeated-measures Analysis of Variance (RM-ANOVA)with Bonferroni adjustment applied for post hoc pairwise comparisons for normally distributed metrics and the Friedman and Mann-Whitney U tests for non-parametric variables, assessing both within-group trajectories and between-group interaction effects across time. Results: Baseline demographic, occupational, and clinical characteristics showed no significant differences between cohorts (p > 0.05). At the 3-month post-treatment mark, both groups exhibited equivalent, statistically significant within-group improvements across all clinical scores (p < 0.01). However, longitudinal trajectories diverged significantly thereafter. Between-group comparative analyses established that the MENS cohort achieved statistically and clinically superior outcomes over the TENS cohort at both 6 and 12 months. Specifically, at the 12-month primary endpoint, between-group comparisons favored MENS for SPADI Pain (mean difference: 14.39 ± 3.51, 95% CI: 7.28 to 21.50, p < 0.001), SPADI Disability (mean difference: 13.56 ± 2.89, 95% CI: 7.71 to 19.42, p < 0.001), NRS pain (mean difference: 2.33 ± 0.32, p < 0.001), and EQ-5D health status (p < 0.001), substantially exceeding established Minimal Clinically Important Difference (MCID) benchmarks. Musculoskeletal ultrasound demonstrated post-intervention stabilization of tear progression in the MENS cohort (0.02 mm secondary depth increase between months 3 and 12), whereas the TENS arm exhibited progressive expansion (0.45 mm increase), presenting a classic clinicoradiological paradox against functional recovery. Conclusions: Both TENS and MENS serve as effective adjunctive modalities for acute symptom alleviation when paired with kinesiotherapy. However, based on robust between-group comparisons, subsensory MENS provides significantly superior long-term clinical durability, tear containment, and functional stability over a 12-month timeline, making it the preferred adjunctive electrophysical intervention for sustained conservative management.