-Original-

Efficacy of a Deep Thermal Therapy System for Osteoarthritis of the Knee

Kazuhiro Harada¹, Kenji Takahashi², Futoshi Ikuta³, Yasuhiro Shindo⁴, Kazuo Kato⁵, Yuya Iseki⁶, Yasushi Oshima³ and Tokifumi Majima³

¹Department of Orthopaedic Surgery, International University of Health and Welfare Hospital, Tochigi, Japan
²Department of Orthopaedics, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kyoto, Japan
³Department of Orthopaedic Surgery, Nippon Medical School, Tokyo, Japan
⁴Faculty of Science & Engineering, Toyo University, Saitama, Japan
⁵Department of Mechanical Engineering Informatics, Meiji University, Kanagawa, Japan
⁶Department of Industrial Systems Engineering, Mechanical System Design Course, National Institute of Technology (KOSEN), Hachinohe College, Aomori, Japan

Background: This study sought to assess the efficacy of a deep-tissue thermal therapy system with a resonant cavity applicator (DTT-RCA), which safely heats deep joint tissue for treating osteoarthritis (OA) of the knee.
Methods: Two groups of participants were recruited. The DTT-RCA group comprised 20 knees. Kellgren-Lawrence (K-L) grade was I and II in 8 knees (DTT-RCA I/II group) [mean age 73.3 years (standard deviation 11.4)], III and VI in 12 knees (DTT-RCA III/IV group) [75.4 (8.6) years]. The control group comprised 13 knees [68.2 (10.8) years]. K-L grade was I in 7 knees and II in 6 knees. This group received exercise therapy. The DTT-RCA I/II group and the control group were imaged by MRI T2 mapping at baseline and 6 months to determine the area of cartilage degeneration.
Results: Visual Analogue Scale improved only in the DTT-RCA I/II post-intervention (p < 0.01). Japanese Orthopedic Association knee rating scores (DTT-RCA I/II: p < 0.01, control group: p < 0.01), the Japanese Knee Osteoarthritis Measure (DTT-RCA I/II: p < 0.05, control: p < 0.01), and the Knee injury and Osteoarthritis Outcome Score (DTT-RCA I/II: p < 0.01, DTT-RCA III/IV: p < 0.05, control: p < 0.01) post-intervention. The magnitude of change did not differ significantly between the three groups. The area of cartilage degeneration did not change significantly post-intervention in the DTT-RCA I/II group, not even relative to the control group.
Conclusions: This was the first study to test a DTT-RCA system in patients with knee OA. The system reduced the clinical symptoms of knee OA and could potentially be effective for conservative therapy.

J Nippon Med Sch 2021; 88: 335-341

Keywords
knee, osteoarthritis, cartilage, conservative treatment, induced hyperthermia

Correspondence to
Kenji Takahashi, MD, PhD, Department of Orthopaedics, Kyoto Prefectural University of Medicine, 465 Kawaramachi-Hirokoji, Kajii-cho, Kamigyo-ku, Kyoto, Kyoto 602-8566, Japan
t-keji@mbox.kyoto-inet.or.jp

Received, May 1, 2020
Accepted, September 11, 2020