Effect of pulsed ultrasound on tibiofemural osteoarthritis
The aim was to evaluate the effect of therapeutic ultrasound on the pain, joint mobility, muscle strength, physical function, and quality of life of people with knee OA. [Subjects and Methods] One-site, one-arm, before-after study that included people with Grade II or III tibiofemoral osteoarthritis. Ten therapeutic ultrasound sessions (duty cycle=20%, ERA=10 cm2, BNR=6:1, SATP=2.2 W/cm2, SATA=0.44 W/cm2, frequency=1 MHz, time=4 minutes) were applied. Assessments of primary outcome variables: pain intensity and function, and secondary variables: joint mobility, muscle strength and quality of life, were performed at onset and end of therapy; an additional intermediate evaluation was included for the primary variables. [Results] Means of repeated measurements of pain intensity (pain at rest, pain on palpation and pain after functional activities) and function showed significant differences. There was a significant reduction in pain intensity at the end of functional activities as well as a significant increase in function and in quadriceps muscle strength. [Conclusion] Therapeutic ultrasound applied in accordance with the parameters used, could be recommended during the treatment of individuals with knee osteoarthritis, because it significantly decreased the intensity of pain after the 5th session, and this reduction was maintained until the end of the intervention.
Keywords: Pain, Ultrasound therapy, Muscle strength
Osteoarthritis (OA) is a chronic and degenerative disorder, characterized by joint cartilage wear. Its main symptoms include pain and reduction of joint mobility and muscle strength. It is one of the conditions with the greatest impact on function and quality of life of the elderly in developed countries1).
In the United States of America (USA), OA affects 12.1% of the adult population, particularly females (RR=1.79)2). In Colombia, the Ministry of Social Protection reported that healthy life-years (HLY, an epidemiological indicator) lost prematurely due to disability and death were similar to HLY lost due to prostate and cervix cancer and leukemia3). The support joint with the highest incidence of OA is the knee with an incidence of 240 new cases per 100,000 person-years compared to hip OA with an incidence of 88 new cases per 100,000 person-years4).
Pain, the main symptom, is present in 38–68% of people with OA and it is associated with insomnia, depression and impairment of participation in social activities3). Moreover, pain has a negative impact on muscle strength and joint Range of Motion (ROM), favoring the progressive decline of function and therefore of the quality of life of these people3).
Therapeutic ultrasound (TUS) is one of the most-used physical modalities of physiotherapy for treatment of knee and hip OA5); however, its application has not shown conclusive effects due to methodological limitations such as small sample size, confounding biases and the lack of clarity about the application parameters, the way ultrasound is generated and the recommended dose for this pathology6).
Few studies7, 8) have been applied the TUS as the only modality of intervention and evaluated its short-term effects of TUS. These authors did not report significant differences in the variables evaluated possibly due to the application of continuous TUS and by methodological limitations such as selection bias, mainly. Regarding the use of pulsed TUS, only a controlled clinical trial included this form of generation in patients with knee OA. Huang et al.9) Reported a significant increase in the ROM of the knee, and decreased pain intensity, however, these authors did not evaluate the short-term effect of TUS.
Therefore, considering the high prevalence of OA in the elderly population and the daily use of TUS in clinical practice, the aim of the present study was to evaluate the effect of TUS applied to the medial and lateral compartments of the knee on pain intensity, joint ROM, muscle strength, function and quality of life of the participants. This study was proposed with the hypothesis that relief of pain might increase knee ROM and the strength of the quadriceps and ischiotibial muscles, and hence give rise to a positive change in the function and quality of life of the participants.