Objective: To evaluate the efficacy of paraffin bath therapy on pain, function, and muscle strength in patients with hand osteoarthritis.

Design: Prospective single-blinded randomized controlled trial.

Setting: Department of physical medicine and rehabilitation in a university hospital.

Participants: Patients with bilateral hand osteoarthritis (N=56).

Interventions: Patients were randomized into 2 groups with a random number table by using block randomization with 4 patients in a block. Group 1 (n=29) had paraffin bath therapy (5 times per week, for 3-week duration) for both hands. Group 2 (n=27) was the control group. All patients were informed about joint-protection techniques, and paracetamol intake was recorded.

Main outcome measures: The primary outcome measures were pain (at last 48h) at rest and during activities of daily living (ADL), assessed with a visual analog scale (0-10cm) at 12 weeks. The secondary outcome measures were the Australian Canadian Osteoarthritis Hand Index (AUSCAN) and the Dreiser Functional Index (DFI), used for subjective functional evaluation, loss of range of motion (ROM), grip and pinch strength, painful and tender joint counts, and paracetamol intake. A researcher blind to group allocation recorded the measures for both hands at baseline, 3 weeks, and 12 weeks at the hospital setting.

Results: At baseline, there were no significant differences between groups in any of the parameters (P>.05). After treatment, the paraffin group exhibited significant improvement in pain at rest and during ADL, ROM of the right hand, and pain and stiffness dimensions of the AUSCAN (P<.05). There was no significant improvement in functional dimension of the AUSCAN and the DFI (P>.05). The control group showed a significant deterioration in right hand grip and bilateral lateral pinch and right chuck pinch strength (P<.05), but there was no significant change in the other outcome measures. When the 2 groups were compared, pain at rest, both at 3 and 12 weeks, and the number of painful and tender joints at 12 weeks significantly decreased in the paraffin group (P<.05). Bilateral hand-grip strength and the left lateral and chuck pinch strength of the paraffin group were significantly higher than the control group at 12 weeks (P<.05).

Conclusions: Paraffin bath therapy seemed to be effective both in reducing pain and tenderness and maintaining muscle strength in hand osteoarthritis. It may be regarded as a beneficial short-term therapy option, which is effective for a 12-week period.