The Effect of Hot Compress in Patients With Knee Osteoarthritis

Knee oteoarthritis (OA) is one of the most common joint diseases worldwide. The prevalence of OA in people aged 20 and over is 203 per 100,000 per year, with 86.7 million people diagnosed with knee OA. In Turkey, the frequency of OA has reached 15%, and it is twice as common in females as in males.

No treatment currently reverses structural deformities caused by OA. Non-pharmacological treatments such as thermotherapy (heat/cold), Tai Chi, yoga, and acupuncture are recommended. Topical applications of herbal extracts and essential oils have also been studied.

Nigella sativa (black cumin) contains thymoquinone, which reduces joint inflammation and rheumatic pain. Zingiber officinale (ginger) has anti-inflammatory and antioxidant effects. Heat application increases blood flow and reduces stiffness and pain.

This randomized controlled experimental study aims to evaluate the effect of hot compress applied with Nigella sativa and Zingiber officinale essential oils on pain, morning stiffness, physical function, and patient satisfaction in knee OA patients.

The study will be conducted at Van Eğitim ve Araştırma Hastanesi, Physical Therapy Unit. Sample size was calculated using G*Power 3.1.7 (α = 0.05, effect size 0.10, power 95%), resulting in 120 participants (30 per group).

Inclusion criteria

aged ≥18 years, physician-diagnosed knee OA, Kellgren-Lawrence stage 3, VAS pain ≥4, no known allergy to the essential oils, no open wound on knee/foot, no knee surgery, not receiving other alternative treatments during the study, and not pregnant.

Exclusion criteria

unwillingness to participate, development of a wound, operation, bruising, or edema in the knee area during the study.

Participants will be randomly assigned to four groups using www.randomization.org:

• Ginger oil + hot compress group
• Black cumin oil + hot compress group
• Sham group (hot compress only)
• Control group (routine treatment only, no additional intervention) A patch test will be performed on the inner forearm with 3 drops of essential oil for participants in groups 1 and 2. If no allergic reaction (dyspnea, itching, redness, rash) occurs within 20 minutes, the participant will be included.

A hot compress will be applied using a thermophore at 40-50°C, wrapped in a thin towel, placed on both knees for 30 minutes, and covered with another towel. This will be performed once daily for 7 days.

Data collection tools:

• Patient Information Form (sociodemographic and clinical characteristics)
• WOMAC (Western Ontario and McMaster Universities Osteoarthritis Index) for pain, stiffness, and physical function
• Visual Analog Scale (VAS) for pain (0-10)
• Visual Analog Scale (VAS) for satisfaction (0-10) Assessments will be conducted at baseline (day 1) and at the end of day 7. Statistical analysis will be performed using IBM SPSS 27.0. Descriptive statistics, ANOVA, Kruskal-Wallis, paired t-test, Wilcoxon, and Friedman tests will be used. Post-hoc tests (Tukey for ANOVA, Dunn for Kruskal-Wallis) will be applied. Significance level will be p < 0.05.

Ethical approval was obtained from Osmaniye Korkut Ata University Scientific Ethics Committee (decision no: 4/12, date: 07.04.2026). Institutional permission from Van Eğitim ve Araştırma Hastanesi will be obtained. Written informed consent will be obtained from all participants.

Inclusion criteria

• Age 18 years or older
• Physician-diagnosed knee osteoarthritis according to American College of Rheumatology (ACR) criteria
• Kellgren-Lawrence grade 3 (moderate) osteoarthritis
• Pain score of 4 or higher on Visual Analog Scale (VAS 0-10)
• No known allergy to Nigella sativa (black cumin) or Zingiber officinale (ginger) essential oils
• No open wounds on the knee or foot
• No previous knee surgery
• Not receiving any other alternative treatment (e.g., acupuncture, herbal therapy) during the study period
• Females must not be pregnant

Exclusion criteria

• Age under 18 years
• Kellgren-Lawrence grade 1, 2, or 4
• VAS pain score below 4
• Known allergy to the essential oils used
• Open wound on knee or foot
• Previous knee surgery
• Receiving other alternative treatment during the study period
• Pregnancy or breastfeeding
• Unwillingness to participate or inability to provide informed consent