Impact of soft tissue around the knee on the efficacy of extracorporeal shockwave therapy in knee osteoarthritis

Knee osteoarthritis (KOA) is the leading cause of knee pain in middle-aged and older individuals. Extracorporeal shockwave therapy (ESWT) has been applied to treat patients with KOA to reduce pain and improve function. Patients (n = 123) diagnosed with KOA who received ESWT were selected to participate in this study, and were grouped according to their body mass index (BMI). The treatment parameters were as follows: 8000 pulses, 2.0 bar, 0.25 mJ/mm(2), and 6 Hz/s once per week for 8 weeks. The visual analog scale (VAS), Lequesne index, and Western Ontario and McMaster University Osteoarthritis Index (WOMAC) were measured to assess knee pain and functional recovery according to BMI groups. Radiographs were used to measure the richness of the soft tissue around the knee joint. The correlation between the distribution of tissue, pain, and functional improvement was analyzed using the receiver operator characteristic curve. All the patients showed a reduction in pain after treatment compared to that before treatment (P < .01). As measured by the VAS, the Lequesne and WOMAC indexes, after the intervention, the pain and functional index of the overweight and above BMI group improved to a greater extent than that of the normal or below normal BMI group (P < .01). The area under the curve showed, with VAS as the demarcation criterion, when the tibial plateau soft tissue ratio, femoral intercondylar apex soft tissue ratio, and medial tibial soft tissue ratio exceeded 1.538, 1.534, and 1.296, respectively, the patient’s pain relief was more pronounced the ESWT treatment was better. With pain in WOMAC as the demarcation criterion, the tibial plateau soft tissue ratio, femoral intercondylar apex soft tissue ratio, and medial tibial soft tissue ratio also are positively correlated with pain relief in patients. When the Lequesne and WOMAC scores were the demarcation criteria, the patients’ function improved significantly when the patella apical soft tissue ratio exceeded 2.401 and 2.635, respectively. ESWT can effectively alleviate pain and improve knee function in patients with KOA, and the soft tissue around the knee joint should also be an important reference factor in KOA treatment.