The PF is a group of elastic and collagenous fibers which originates from the medial part of the calcaneus and is attached to the forefoot along with various other tissues. Under the effect of chronic strain, elastic fibers become straight and stiffening of the fascia occurs .
Plantar heel pain can be linked to calcaneal spur, a condition that affects many people of all ages. It is a bony outgrowth on the heel bone. The spur tip site is within the PF origin leading to persistent traction on the PF and triggering its inflammation . Calcaneal spur can be symptomatic especially with aging, obesity, in female patients, and in patients with history of osteoarthritis .
It is usually a self-limiting condition. Most of the patients’ symptoms are relieved by conservative treatments such as corticosteroid injection, NSAIDS, rest, and using orthotics . Sometimes, therapeutic modalities can be used such as therapeutic ultrasound .
There is an agreement that about 90% of heel pain improve with conservative measures and that surgical management can be considered after failure of these non-operative measures. It was reported that ESWT might be a good alternative to surgical maneuvers which might carry the risk of complications .
ESWT has been used recently as a noninvasive and effective modality in the treatment of patients with chronic heel pain who are resistant to other commonly used conservative treatments . FDA approved ESWT as a non-surgical treatment technique in patients with symptomatic plantar fasciitis, who are resistant to other commonly used conservative treatments . Also, the FDA approved its use in 2002 in patients with symptomatic heel spurs after the positive results of Buch et al. .
Ultrasonography is an important tool in the diagnosis and evaluation of patients with plantar fasciitis through the detection of thickening of the PF and its hypoechogenic pattern at calcaneal insertion .
There might be a debate regarding the clinical outcome of using ESWT as a therapeutic option in the treatment of symptomatic calcaneal spur [22, 23].
Our aim was to evaluate the efficacy of ESWT for plantar fasciitis in calcaneal spur patients by musculoskeletal ultrasonography.
In the present study, patients were more frequently females (80%), mostly obese, their mean BMI was 32.4 ± 4.29, and their mean duration was 44.18 ± 8.61 years which was in accordance with the results of previous studies which reported that the risk of plantar fasciitis is linked to increased BMI . Patients in the present study had prolonged standing hours with a mean of 6 h, thus indicating the importance of mechanical factors in this disease and supporting the results of other studies which concluded that plantar fasciitis might be associated with behaviors and occupations related to weight bearing and increased standing .
The thickness of PF was measured by ultrasound 2 cm distal to the calcaneal tuberosity. In addition, the level of pain was recorded in the VAS scale and RMS was used as a functional evaluation method. A thickness of the PF more than 4 mm is indicative of plantar fasciitis . In our study, a mean PF thickness in calcaneal spur patients (5.66 ± 1.14 mm) was significantly greater than in the asymptomatic control individuals (2.40 ± 0.35 mm).
The main targets of therapies in plantar fasciitis are to decrease the level of pain and increase the level of function. In the present study, we detected high statistical significance regarding pain degree and functional evaluation in plantar fasciitis before and after ESWT treatment P < 0.001), supporting the results of previous studies including Cheing and Chang in 2007  and Ulusoy et al. in 2017 . In 2013, a metanalysis study reported a decrease in the pain and RMS on using ESWT compared to placebo in contrast to other studies which concluded that ESWT is ineffective in the treatment of plantar fasciitis , indicating that assessment of the role and the efficacy of ESWT must be continued as long as there is controversy to detect a conclusive response regarding the target disorder.
Measuring PF thickness can give an idea regarding the effect of the therapeutic device used. According to our study, there was a significant decrease in the thickness of the PF before and after treatment suggesting that it might be used as an objective tool in the follow-up of plantar fasciitis treatment using ESWT.
This study found that the PF thickness was strongly correlated with the number of standing hours and BMI, which might suggest that decreasing the number of standing hours and reducing body weight might prevent the development of plantar fasciitis; further studies should be done to investigate this finding.
There was no statistically significant correlation between clinical data (VAS and RMS) and PF thickness after ESWT; this might be due to the short duration of the follow-up. Further studies with a longer duration of follow-up are recommended which might reveal the association between reduction in PF thickness and clinical data as pain and functional scores.