RESUMEN
Background: This study is primarily aimed to determine whether transcutaneous electrical nerve stimulation (TENS) and interferential current (IFC) treatments have any effect on central sensitization (CS) in patients with knee osteoarthritis (OA) and to investigate which treatment is more effective. Methods: In this randomized controlled trial, 80 patients were randomized into four treatment groups: TENS, Plasebo-TENS, IFC, and Plasebo-IFC. All interventions were applied 5 times a week for 2 weeks. Primary outcome was pressure pain threshold (PPT), which is accepted as the objective indicator of CS, at the painful knee and at the shoulder as a painless distant point. Other outcome measures were the visual analog scale (VAS), Western Ontario and McMaster Universities Osteoarthritis Index, Timed Up and Go Test, pain catastrophizing scale, Beck Depression Inventory, and Tampa Scale of Kinesiophobia. Results: All assessment parameters were improved, without a significant difference among the groups except PPT. PPT scores were significantly improved in TENS and IFC groups when compared with the sham groups at 2 weeks and 3 months. In addition, this improvement was even more pronounced in the TENS group. Multivariable logistic regression analysis showed that the patient's inclusion in the TENS group, an initial high PPT, and an initial low VAS score were independent risk factors for improvement in the PPT. Conclusions: This study shows that TENS and IFC reduced pain sensitivity as compared to placebo groups in patients with knee OA. This effect was more pronounced in the TENS group.
RESUMEN
BACKGROUND: Physical modalities have been safely used for decades for pain relief and for reducing physical disability in the conservative treatment of knee osteoarthritis (OA). However, patients' response to treatment is highly variable, which may be related to certain patient-related factors such as pain catastrophizing and depression. OBJECTIVES: This study aimed to evaluate the effects of pain catastrophizing and depression on physical therapy outcomes and to identify the baseline factors predictive of poor outcomes in patients with knee OA. STUDY DESIGN: This research used a prospective, cohort, observational study design. SETTING: The research took place in an outpatient physical therapy unit within a tertiary hospital in Ankara, Turkey. METHODS: Eighty-nine patients with knee OA underwent 10 sessions of physical therapy. At baseline, depression and pain catastrophizing were evaluated using the Beck Depression Inventory-II (BDI-II) and the Pain Catastrophizing Scale (PCS). The therapeutic efficacy of physical therapy was assessed based on the level of pain and disability using the Visual Analog Scale (VAS) and the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC). Changes in the VAS score and WOMAC were evaluated at 2 and 6 weeks following physical therapy. A multivariate logistic regression analysis was conducted to identify the predictors of poor outcomes. RESULTS: Patients with low pain-catastrophizing and low depression scores tended to demonstrate better improvement at weeks 2 and 6. The results of a multivariate logistic regression analysis showed that the significant outcome predictor for both pain and function at week 6 was the baseline PCS score. The baseline depression score was not an independent predictor of a clinically poor outcome. LIMITATIONS: This study is limited owing to the combined use of several physical therapy modalities and short follow-up. CONCLUSIONS: This study suggests that the baseline PCS score is a predictive factor of poor response to physical therapy in patients with knee OA. Considering this factor before therapy and taking the necessary precautions may improve the outcomes of physical therapy. KEY WORDS: Catastrophization, central nervous system sensitization, depression, disability evaluation, knee osteoarthritis, pain, physical therapy modalities, transcutaneous electric nerve stimulation.
