Knee osteoarthritis (OA) is the most common form of OA, with an estimated prevalence between 12% and 35% in the general population (Pop et al. 2007, Quintana et al. 2008) and is the leading cause of musculoskeletal disability in the elderly population worldwide Zhang and Jordan, (2010). Physiotherapy is often recommended for the management of painful knee OA Zhang et al. (2008) and ultrasound therapy (US) is one of the most common physical agents used within this treatment (Bélanger 2003).
Recommendation:
- Continuous or pulsed 1mhz and 3mhz have been used
- 1mhz 1 -2.5 W/cm2
- 3mhz 0.5-1.5 W/cm2
- 4-15 mins (10 is average)
- Frequency = 1x per day down to 1 x per week (3 per week is average)
- Session 1-24 (10 is average)
- Combine with =
- Heat or ice
- Home exercises (mobility and strength)
The Osteoarthritis Research Society International (OARSI) did a systematic review of existing treatment guidelines (2007) in order to develop recommendations for the management of knee and hip OA (Zhang et al. 2008). Ultrasound was not identified as a core treatment modality based on the results of a systematic review published in 2001 by the Cochrane Collaboration (Welch et al. 2001). The Cochrane systematic review included studies available prior to June 2001 while more recent trials evaluating the effectiveness of US in the management of knee OA were not reviewed.
In 2010 Loyola-Sánchez, Richardson, and MacIntyre looked at the newer literature in US and OA of the knee they found six studies of suitable quality (out of 33 available) they said overall, the application of US resulted in decreased pain. Effect estimates favoured US therapy; however, the differences were statistically significant only in the low intensity/pulsed US and US dose < 150 J/cm2 subgroups. Overall, trials that reported VAS at 12 months (10 months after completing the interventions) favoured US.
In 2014 Zeng et al. reviewed the literature to establish whether pulsed or continuous US was better they found that Pulsed US (PUS) is more effective in both pain relief and function improvement when compared with the control groups; but for continuous US (CUS), there is only a significant difference in pain relief in comparison with the control group. In addition, no matter in terms of pain intensity or function at the last follow-up time point, PUS always exhibited a greater probability of being the preferred mode. However, the evidence of heterogeneity and the limitation in sample size of some studies could be a potential threat to the validity of results.
Later 2 studies in 2016 did further analysis of the literature:
Zhang et al. (2016) – Therapeutic ultrasound showed a positive effect on pain. For physical function, therapeutic ultrasound was advantageous for reducing Western Ontario and McMaster Universities physical function score. In terms of safety, no occurrence of adverse events caused by therapeutic ultrasound was reported in any trial.
Wu et al. (2016) – Meta-analyses demonstrated that therapeutic ultrasound significantly relieved pain and reduced the Western Ontario and McMaster Universities (WOMAC) physical function score. In addition, therapeutic ultrasound increased the active range of motion and reduced the Lequesne index. Subgroup analysis of phonophoresis ultrasound illustrated significant differences on the visual analogue scale, but no significant differences on WOMAC pain subscales, and total WOMAC scores were observed. There was no evidence to suggest that ultrasound was unsafe treatment.
Earlier randomised control trials have all suggested beneficial effects.
Cetin et al. (2008) studied Women with mild to severe bilateral knee OA they used a Sonopulus 590 US device, continuous mode, 1.5 W/cm2 intensity, 180 J/cm2, 24 ten-min sessions in 8 weeks combined with standardized warm up, isokinetic exercises, and hot pack. Pain and disability index scores were significantly reduced in each group. Patients in the study groups had significantly greater reductions in their visual analogue scale scores and scores on the Lequesne index than did patients in the control group (group 5). They also showed greater increases than did controls in muscular strength at all angular velocities.
Falconer et al. (1992) looked at men and Women 72% they used a Chattanooga Intellect 200 US device, continuous mode 1.7 W/cm2 intensity,
26 J/cm2 dose, 12 twelve-min sessions in 4 to 6 weeks. Paired t-tests revealed that both groups significantly improved in active ROM, pain, and gait velocity, and maintained improvement for at least 2 months.
Huang et al. (2005a) 81% Women with mild knee OA used continuous US, 1.5 W/cm2 intensity, 270 J/cm2 dose in one group and pulsed mode (duty cycle: 25%), 2.5 W/cm2 intensity, 112.5 J/cm2 dose in a second group. 24 fifteen-min sessions in 8 weeks. combined with standardized warm up, isokinetic exercises and hot pack (home exercise program following 8 weeks). Subjects were randomized sequentially into 1 of 4 groups. Group I received isokinetic muscular strengthening exercises, group II received isokinetic exercise and continuous US, group III received isokinetic exercise and pulsed US treatment, and group IV was the control group. Each treated group had increased muscle peak torques and significantly reduced pain and disability after treatment and at follow-up. However, only patients in groups II and III had significant improvement in ROM and ambulation speed after treatment. Fewer participants in group III discontinued treatment due to knee pain during exercise. Patients in group III also showed the greatest increase in walking speed and decrease in disability after treatment and at follow-up. Gains in muscular strength in 60°/s angular velocity peak torques were also noted in groups II and III. However, group III showed the greatest muscular strength gains with 180°/s angular velocity peak torques after treatment and follow-up.
Huang et al. (2005b) 81% Female with mild knee OA, Sonopulus 590 US device, pulsed mode (duty cycle: 25%), 2.5 W/cm2 intensity, 112 J/cm2 dose, 24 fifteen-min sessions in 8 weeks combined with standardized warm up, isokinetic exercises and hot pack (home exercise program following 8 weeks). Group I received isokinetic exercises; group II received isokinetic exercise and pulse ultrasound for periarticular soft tissue pain; group III received isokinetic exercise, pulse ultrasound, and intraarticular hyaluronan therapy; and group IV acted as the control group. The therapeutic effects of the interventions were evaluated by changes in VAS, Lequesne’s index, knee range of motion, peak muscle torques of knee flexion and extension, and ambulation speed after 8 weeks of treatment and at follow up 1 year later. Pain scores for groups I–IV were initially similar, but pain scores decreased significantly in all treated groups, and pain scores had continued to decrease significantly in groups II and III at the follow up, whereas pain scores increased in the controls. Patients in group III showed the greatest degree of pain reduction, both after treatment and in the followup period. . Patients in groups I–III exhibited increased muscle peak torques and significantly reduced pain and disability after treatment and at follow up. Groups II and III showed significant improvements in range of motion and ambulation speed after treatment. Group III also showed the greatest increase in walking speed and decrease in disability after treatment and at follow up. Both group II and group III had significant gains in muscular strength after treatment and at follow up; group III showed the greatest gains
Ozgonenel et al. (2009) 80% Women with mild to moderate knee OA continuous US, 1 W/cm2 intensity, 150.72 J/cm2 dose, 10 five-min
sessions in 2 weeks. In the treatment group, the improvement in VAS score was statistically and significantly higher and more pronounced than in the placebo group. Pain reduction averaged 47.76% in the treatment group. Secondary outcomes improved in both groups but reached statistical significance only in the treatment group. The mean change in total WOMAC scores and p = 0.041 for 50 meters walking time. Results suggested that therapeutic US is safe and effective treatment modality in pain relief and improvement of functions in patients with knee OA.