Deep friction massage versus local steroid injection for treatment of plantar fasciitis: a randomized controlled trial

Deep friction massage (DFM) has long been proven to be effective in treatment of some tendinopathies. The aim of our study was to evaluate the efficacy of this physical modality in the treatment of plantar fasciitis in comparison with local steroid injection. Sixty patients were assigned into 2 groups through a computer-based randomization table and completed the treatment and follow-up assessments; thirty in group I received 40 mg local triamcinolone injection and thirty in group II received 7 sessions of DFM. Demographic data showed a statistically insignificant difference in age, female to male ratio, and body mass index (BMI) in both groups. The mean for age was 39.42 years in group I and 41.32 years in group II (P = 0.86); the female to male ratio was 3:1 in group I and 2.75:1 in group II, and the mean for BMI was 32.41 in group I and 33.31 in group II (P = 0.51). At 2 and 6 weeks follow-up, DFM led to less improvement in pain and function compared to local steroid injection (P = 0.001 and 0.002 for pain and P = 0.001 and 0.001 for function respectively at both time points of follow-up). This study revealed that deep friction massage is not effective as a single method in treatment of the plantar fasciitis. However, it can be used as an adjuvant physical modality. Further, large scale studies are needed to support this observation. Pan African Clinical Trial Registry PACTR202004672785790. Date of registration 16 April 2020, “retrospectively registered.”

To our knowledge, this is the first study to evaluate the effectiveness of deep friction massage as a single modality for the treatment of plantar fasciitis. While this physical modality has been claimed to be effective for treatment of some tendinopathies, this efficacy could not be confirmed in this study for plantar fasciitis.

Background
Plantar fasciitis (PF) is a common pathological condition that can lead to significant pain and disability [1]. It has been reported as the third most common running-related health problem [2] but can also affect non-athletes and less active elderly people [3]. PF occurs in a wide range of age with the mostly affected being between 40 and 60 years [4]. While the main cause of the condition is not known, several risk factors have been reported, but the most accepted theory is repetitive micro tearing and subsequent chronic inflammation of the plantar fascia at its insertion to the medial calcaneal tubercle [5].
Although often self-limiting, about 10% of patients may have persistent pain and marked disability [6]. Several interventions are routinely used for treatment of the condition including arch supports, strapping, heel pads, extracorporeal shock wave therapy, laser, topical applications, and surgical interventions [7]. Local injection using long acting steroids has been reported as an effective method for decreasing pain and improving function in PF especially on the short term [8,9].
Although physical modalities resemble the cornerstone in the conservative treatment of PF, evidence is lacking which method is more effective [10].
Deep friction massage (also known as cross friction massage) has long been studied as a physical treatment for many musculoskeletal conditions especially tendinopathies depending on the fact that it can promote optimal collagen healing by increasing circulation and decreasing collagen cross linking [11].
It has recently been shown to be effective in the treatment of lateral epicondylitis [12].
However, there is a scarcity of studies about the use of this modality in podiatry problems as PF.
In this study, we aimed to evaluate the efficacy of DFM in the treatment of plantar fasciitis.

Methods
Between November 2018 and May 2019, a total of 60 adult patients with plantar fasciitis were selected from those attending the outpatient clinics of the rheumatology and rehabilitation departments of our institutions after giving an informed consent and completed the follow-up assessments (flow diagram Fig. 1). Patients were diagnosed as having plantar fasciitis according to the following criteria which have been proposed by the International Statistical Classification of Diseases and Related Health Problems (ICD) category of plantar fasciitis [13]: pain in the plantar medial heel region on palpation pain most noticeable with initial steps after a period of inactivity but also worse following prolonged weight bearing; and pain often precipitated by a recent increase in weight-bearing activity.
Exclusion criteria included patients with diabetes mellitus, peripheral vascular disease, and those who previously received systemic or local steroid injection within 3 months or locally injected with any other material and those who had rheumatic or connective tissue diseases or Achilles tendinopathy. Patients with foot pain due to arthritis, trauma, infection, or neurological problem and those with previous surgical intervention in the heel were also excluded. The study was approved by our institutions ethical committees and it conforms with the declaration of Helsinki for human experimentations. This study adheres to 2010 CONSORT guidelines.

Procedure
The data collected from each patient included age, gender, disease duration, previous treatments, body mass index (BMI), and the presence of associating low back pain and sciatica. Plain radiography was done for each affected heel on lateral view for diagnosis of associating calcaneal spur. Before treatment, at 2 weeks and 6 weeks follow-up, patients were instructed to identify the degree of pain felt with the first steps after long standing and in the early morning using the visual analog scale (VAS) from 0-10 where zero resembles no pain and ten resembles the worst pain and to complete the questionnaire about the function level and activity using the first seven items of the foot function index (FFI) as the remaining two items are related to orthotic use and were not applicable in this study [14].
According to a computerized randomization table, the patients were randomly assigned into the following two groups including the patients that completed the followup assessments: Group I: thirty patients (41 heels) receiving local injection with triamcinolone acetonide 40 mg/1 ml plus lidocaine 2%/1 ml. The affected heel was completely sterilized and then slowly injected using the medial approach into the most tender point while the patient is in supine position. The patients were then advised not to do any long standing or walking activity for 2 days.
Group II: thirty patients (36 heels) receiving 7 sessions (10 min each) of deep transverse friction massage (DFM) performed every other day by a welltrained nurse in the physical therapy units as follows: with the reinforced thumb, a friction massage was applied transversely across the plantar fascia from proximal to distal on the most tender point in a rate of about 2 to 3 cycles per second within the patient's tolerance.

Statistical analysis
Statistical analyses were performed using SPSS Ver. 21.0 (SPSS Inc/IBM, Chicago, IL, USA). Categorical variables were described by number and percent (No and %), where continuous variables were described by mean and standard deviation (mean ± SD). Chi-square and Fisher's exact tests were used to determine the differences in proportions for each variable. Analysis of variance (ANOVA) was performed to compare means of continuous variables between the two groups. P value of less than or equal to 0.05 was considered significant.

Results
The numbers of participants who were randomly assigned, received intended treatment, and were analyzed for the outcome measures are shown in the flow diagram (Fig. 1). The mean age of our patients was 39.42 years (range 19-65) in group I and 41.32 (range 23-63) years in group II (P = 0.86), and the female to male ratio was 3:1 in group I and 2.75:1 in group II. Bilateral PF was diagnosed in 25% of all patients. X-ray diagnosed the presence of calcaneal spur in 73% and 91% in group I and II respectively. The demographic and clinical features are shown in Table 1.
At the follow-up assessments, there was a significant difference between the two groups with more improvement of pain and function in the group of local steroid injection (P = 0.001 at 2 weeks and 0.002 at 6 weeks for pain depending on the mean VAS), while for function  (Table 2).

Discussion
Current treatment of PF includes several physical and rehabilitation modalities as stretching exercise, arch supports, laser, and extracorporeal shock wave therapy [7]. Deep friction massage (DFM), developed by Cyriax [15], is a well-known manual treatment for tendinopathies. Cyriax proposed that DFM can lead to traumatic hyperemia and increased blood flow to the tissue, diminution of adhesions, and mechanoreceptor stimulation. It has been also hypothesized that DFM acts through the gate control theory by modulating the nociceptive impulses and inhibition of the A-delta C fibers at the level of the spinal cord which are responsible for transmitting the pain by stimulating the large fibers [16]. Myofascial technique, a deep manual method similar to DFM, has been hypothesized to enhance fibroblast proliferation and promoting collagen synthesis that may lead to healing of PF by replacing the degenerative tissue with a more functional one [17]. To the best of our knowledge, this is the first study to evaluate the efficacy of DFM in improving the pain and function in patients with plantar fasciitis in comparison with local steroid injection as an established extensively studied shortterm method of treatment [10]. We adopted the visual analog scale for pain assessment and the first seven items of the FFI to measure the function and daily living activities as previously reported [18,19].
We found that DFM is less effective than local steroid injection for PF at 2 and 6 weeks follow-up. In their study comparing DFM with local steroid injection for treatment of lateral epicondylitis, Yi et al. recently reported a significantly beneficial effect of DFM [12]. Vasseljen recommended the combination of both local steroid injection and DFM for treatment of lateral epicondylitis in their study comparing DFM with several modalities as pulsed ultrasound and laser treatment. He also stated that DFM is more effective than these physical modalities in decreasing pain and increasing the wrist extension strength [20].
On the other hand, Senbursa et al. reported that DFM is more effective in increasing strength and decreasing pain of the supraspinatus tendon in patients with shoulder impingement syndrome when comparing this modality with strengthening exercises in their randomized controlled trial [21]. In a recently published randomized cross-over trial on athletes with patellar tendinopathy, Chaves et al. reported that DFM induces an immediate reduction in pain intensity upon palpation. The authors aimed to assess the immediate analgesic effect of DFM and whether this effect can be influenced by the amount of pressure applied during the sessions. However, this study is strongly limited by the small sample size (ten patients) which needs caution with results interpretation as concluded by the authors [22]. In line with our findings, a pilot study comparing home exercise program with DFM and home exercise program alone for treatment of chronic PF showed an improvement of pain and function in both groups without beneficial effect of the addition of DFM but failed to find a significant difference due to the small sample size (24 patients) [23].  The minimal effect of DFM in treatment of PF may be explained by the difference in the pathogenetic mechanisms between PF, lateral epicondylitis, supraspinatus tendon impingement and patellar tendinopathy, the microstructural difference between the tendon and fascia, and the relatively deeper position of plantar fascia. Nevertheless, more large scaled studies with long-term follow-up are needed to support our results.
Our study has some limitations as the small sample size and the absence of ultrasonographic evaluation before and after treatment as a reliable objective technique used to detect the abnormalities of PF such as the change of echogenicity and the increased thickness of the fascia.

Conclusion
This study revealed that deep friction massage solely is less effective than local steroid injection in decreasing pain and improving function in patients with plantar fasciitis. However, it could be used as an adjuvant modality of physical therapy.