Abstract
BACKGROUND AND PURPOSE: Recent investigations into carpal biomechanical and ligamentous properties associated with dynamic scapholunate (SL) instability have contributed to the development of conservative treatment approaches. The aim of this study was to investigate the impact of isolated neuromuscular electrical stimulation (NMES) training of the forearm muscles combined with structured exercise training on weight bearing, muscle strength, proprioceptive sensation and upper limb functionality in individuals diagnosed with SL instability. METHODS: This randomized, single-blind, controlled study included 30 patients (26 females / 4 males) aged between 18 and 50 years, who had been diagnosed with SL instability. The patients were randomly assigned to one of two groups: the Exercise Group (EG), who received an exercise program alone, and the Neuromuscular Electrical Stimulation Group (NMESG), who received NMES in addition to the same exercise program. The NMES protocol was applied three days a week for eight weeks, with 15 min each for the abductor pollicis longus, flexor carpi radialis, extensor carpi radialis longus, and extensor carpi radialis brevis muscles, for a total of 60 min. Each patient also exercised daily at home throughout the eight-week period. Exercise training was prescribed seven days per week. On clinic days, one supervised session was completed in the clinic, followed by two additional unsupervised home-based sessions later the same day. On non-clinic days, patients performed three unsupervised home sessions each day. The primary outcome measure was upper extremity disability, assessed using the QuickDASH questionnaire. The secondary outcome measures included activity-related pain (assessed using the Visual Analog Scale during activity (VAS-a)), wrist range of motion (ROM), the weight-bearing tolerance test (WBT), isokinetic muscle performance, grip strength, and proprioceptive sense. Pain was evaluated five times in total: at baseline and every two weeks thereafter. All the other assessments were performed twice: at baseline and at the end of the 8th week. RESULTS: Significant improvements from before to after the intervention were observed in all parameters in both groups (p < 0.001). Statistically significant improvements were observed in the NMESG compared to the EG in terms of QuickDASH scores, VAS-a, WBT, and endurance in flexion (p < 0.005). Decreases in pain levels during activity were more pronounced in the NMESG from baseline to the 2nd, 4th, and 8th weeks of follow-up (p < 0.05). CONCLUSION: The study results demonstrated that the application of NMES to target muscle groups together with stability-enhancing exercise strategies supports functional recovery. These findings are instructive in determining the ideal rehabilitation strategies for NMES applications as a conservative treatment for SL instability. TRIAL REGISTRATION: The study was registered at ClinicalTrials.gov under ClinicalTrials registration number NCT06627296 on 01/10/2024.