Dry cupping for plantar fasciitis: a randomized controlled trial (2024)

Abstract

[Purpose] The purpose of this study was to determine the effects of dry cupping on painand function of patients with plantar fasciitis. [Subjects and Methods] Twenty-ninesubjects (age 15 to 59 years old, 20 females and 9 males), randomly assigned into the twogroups (dry cupping therapy and electrical stimulation therapy groups), participated inthis study. The research design was a randomized controlled trial (RCT). Treatments wereprovided to the subjects twice a week for 4 weeks. Outcome measurements included theVisual Analogue Pain Scale (VAS) (at rest, first in the morning, and with activities), theFoot and Ankle Ability Measure (FAAM), the Lower Extremity Functional Scale (LEFS), aswell as the pressure pain threshold. [Results]The data indicated that both dry cuppingtherapy and electrical stimulation therapy could reduce pain and increase functionsignificantly in the population tested, as all the 95% Confidence Intervals (CIs) did notinclude 0 except for the pressure pain threshold. There was no significant differencebetween the dry cupping therapy and electrical stimulation groups in all the outcomemeasurements. [Conclusion] These results support that both dry cupping therapy andelectrical stimulation therapy could reduce pain and increase function in the populationtested.

INTRODUCTION

Adult heel pain is usually caused by plantar fasciitis1^,2^,3^,4⁾, the most common footcondition diagnosed and treated by healthcare providers5⁾. The onset of pain is usually gradual and typically occurs at theplantar medial heel6⁾. Most patientsexperience pain and tightness when taking their initial steps in the morning immediatelyafter standing up from bed or after a period of prolonged rest such as sitting at the deskduring the day1^, 3^, 5⁾. The pain usually improvesafter walking for a short period of time but could intensify after prolonged weight-bearingactivities, including standing, walking, or running. Plantar fasciitis affects millions ofAmericans every or 10 percent of the population of the United States5^, 7⁾. Economic costsfrom third-party payers relating to the treatment of plantar fasciitis have been estimatedto range from $192 to $376 million per year8⁾.

The plantar fascia is a thick fibrous aponeurosis formed from 3 bands of dense connectivecollagen fibers that attach proximally to the medial calcaneal tuberosity and fans distallyto the flexor tendon sheaths and the base of the proximal phalanges4^, 9^, 10⁾. This important structure provides the static and dynamicsupports for the arch of the foot by transmitting forces between the heel and forefootduring weight-bearing activities. As the terminology of plantar fasciitis implies, plantarfasciitis has traditionally been considered an inflammatory process. However, recentfindings suggest plantar fasciitis be a chronic degeneration causing marked thickening andfibrosis of the plantar fascia along with collagen necrosis, chondroid metaplasia, andcalcification4^, 10⁾. Hence, it has been advocated that plantar fasciosism may be a moreappropriate terminology compared to plantar fasciitis1^, 4⁾. While the diagnosis ofplantar fasciitis is usually based on patient history, risk factors, and findings fromphysical examination1⁾, because the chronicdegeneration healing mechanism is poorly understood, treatment of plantar fasciitis is oftendifficult4⁾. Little convincing evidenceis available to support various approaches for treating plantar fasciitis1⁾. For example, mobilization of ankle and footjoint was recently found no more effective than stretching and ultrasound alone in treatingplantar fasciitis11⁾. For chronicrecalcitrant plantar fasciitis that lasts more than six months after conservative treatment,surgery is recommended1⁾. Additionally,recent evidence has demonstrated that dry needling can significantly reduce plantar heelpain12⁾. However, the revised ClinicalPractice Guidelines released by the Orthopaedic Section of the American Physical TherapyAssociation (APTA) titled “Heel Pain—Plantar Fasciitis: Revision 2014” states that “triggerpoint dry needling cannot be recommended for individuals with heel pain/plantarfasciitis”6⁾.

Cupping therapy has recently gained the attention of the media and the public at the RioOlympics, with extensive media coverage of the dark red circles left on Olympians’ shouldersand backs, telltale signs of cupping therapy. Although cupping therapy has been performed inmost cultures historically13^, 14⁾, this manual modality is mostly believed to be an ancienttherapy primarily used in China and other Asian countries for thousands of years15^, 16⁾. This alternative therapy involves creating a vacuum inside a cuppositioned over the surface of the skin, using the local negative pressure to promote bloodflow17^, 18⁾. A few Systematic Reviews (SRs) of randomized clinical trials(RCTs) have been conducted to determine the effectiveness of cupping therapy in treatingpain19⁾, hypertension20⁾, and stroke21⁾. The total number of RCTs meeting the inclusion criteria of the SRswere limited to determine the effectiveness19^,20^,21⁾.The quality of most of the RCTs were poor19^,20^,21⁾.Based on the currently available SRs, the effectiveness of cupping has been demonstratedonly as a treatment for pain22⁾.

Cupping therapy may be a low-cost alternative to treat plantar fasciitis. To our knowledge,there is no research on the effectiveness of cupping therapy on pain and function forpatients with plantar fasciitis. The purpose of this study was to determine the effects ofdry cupping, a type of cupping therapy, on pain and function of patients with plantarfasciitis. The significance of this research project is that it may provide insight tophysical therapy management of plantar fasciitis, particularly with regards to cuppingtherapy.

SUBJECTS AND METHODS

Twenty-nine subjects (age 15 to 59 years old, 20 females and 9 males) were recruitedthrough a convenience sampling on the university campus using flyers posted on bulletinboards around campus and word of mouth. Data for body weight and height for each subjectwere not collected. The inclusion criteria included heel pain with a current or previousdiagnosis of plantar fasciitis from a physician or with patient history, risk factors, andphysical examination findings consistent with plantar fasciitis, and between 15 and 60 yearsof age. The exclusion criteria included contraindications to manual therapy or electricalstimulation, including tumors, recent fractures (<6 months), rheumatoid arthritis,prolonged history of steroid use, severe vascular disease, open wounds, recent surgery toankle joint or rear foot region (<6 months), impaired sensation, pacemaker, and implants;inability to comply with treatment or the follow-up protocols; and currently undergoingother treatments for heel pain. Ethics approval for this study was sought and obtained fromthe Institutional Review Board at Youngstown State University. Written informed consent wasobtained from each subject.

The research design was a randomized controlled trial. Subjects were randomly assigned tothe dry cupping therapy (experimental) group (n=14, age 40.1 (SD 14.6) years old, 10 femalesand 4 males) or the electrical stimulation therapy (control) group (n=15, age 39.3 (SD 13.5)years old, 10 males and 5 females). There was no significant difference between the ages ofthe two groups (p=0.36).

The sample size was determined using G*Power 3.1 (version 3.1.9.2) with the followingparameters: effective size of 0.5, alpha of 0.05, and power of 0.80. The total number ofsubjects was calculated to be 22.

Treatments were provided to the subjects twice a week for 4 weeks. In the dry cuppingtherapy group, a plastic cupping bell (Kangzhu 6-Cup Biomagnetic Chinese Cupping TherapySet, Model B1 × 6, Kangzhu, Beijing, China) was applied to the painful site for 10 minutesin each session. A manual hand pump was used to create the vacuum for suction. The intensityof the vacuum was based on subject tolerance. In the electrical stimulation therapy group,the subjects were provided with electrical stimulation therapy, a therapeutic modalityroutinely used by physical therapists for pain management, using a cabinet, multi-currentstimulator (Dynatron Solaris 709, Dynatronics, Salt Lake City, UT, USA). The electrodes wereplaced around the painful site, and pre-modulated interferential current electricalstimulation was conducted for 10 minutes. The intensity of the current was increased topatient tolerance at the sensory level. The carrier frequencies were 4,000 Hz and4,000–4,150 Hz. The beat frequency was 80–150 Hz.

Outcome measurements included the Visual Analogue Pain Scale (VAS) (at rest, first in themorning, and with activities), the Foot and Ankle Ability Measure (FAAM), the LowerExtremity Functional Scale (LEFS), as well as the pressure pain threshold. Pressure painthreshold was measured 3 times using a hand-held digital dynamometer (Lafayette ManualMuscle Tester Model 01163, Lafayette Instrument Company, Lafayette, IN, USA) at the mostpainful spot in the painful area. The subjects were instructed to report to the investigatorwhen they started to feel pain or discomfort while the investigator gradually increased theforce applied to the painful area through the dynamometer. A familiarization trial wasconducted for pressure pain threshold for each subject. The pressure pain threshold wasdetermined as the mean of the three trials. Outcomes were measured at baseline and at eachsession for VAS or every other session for all other outcome measurements.

Changes in VAS, FAAM, LEFS, and pain threshold are reported as means and 95% confidenceintervals (lower, upper 95% confidence interval). Student t-tests were used to determinewhether there were statistically significant differences in the changes in the outcomemeasurements between the experimental and control groups. Significance was determined atα=0.05.

RESULTS

The data indicated that both dry cupping therapy and electrical stimulation therapy couldreduce pain and increase function significantly in the population tested. However, there wasno significant difference between the dry cupping therapy and electrical stimulation groupsin all the outcome measurements.

For the VAS, the mean changes in average score (at rest, first in the morning, and withactivities) were −29.8 (−39.4, −20.1) mm in the dry cupping therapy group compared to −28.0(−36.7, −19.2) mm in the electrical stimulation therapy group. There was no statisticallysignificant difference between the two groups (p=0.39).

For the FAAM, the mean changes in score were 16.9 (7.8, 26.0) % in the dry cupping therapygroup compared to 12.9 (8.2, 17.6) % in the electrical stimulation therapy group. There wasno statistically significant difference between the two groups (p=0.27). The mean changes inpatient perceived function were 12.3 (7.6, 17.0) % in the dry cupping therapy group comparedto 14.3 (5.5, 23.0) % in the electrical stimulation therapy group. There was nostatistically significant difference between the two groups (p=0.36).

For the LEFS, the mean changes in score were 19.6 (8.6, 30.7) % in the dry cupping therapygroup compared to 11.4 (7.7, 15.1) % in the electrical stimulation therapy group. There wasno statistically significant difference between the 2 groups (p=0.08).

For the pressure pain threshold, the mean changes in threshold were 4.6 (0.0, 9.1) lb inthe dry cupping therapy group compared to 1.7 (−2.7, 6.0) lb in the electrical stimulationtherapy group. There was no statistically significant difference between the 2 groups(p=0.19). All the within-group changes were significant except for the pain threshold, asall the 95% CIs did not include 0 except for the pain threshold.

DISCUSSION

To our knowledge, this is the first study on the effectiveness of dry cupping therapy onthe pain and function of patients with plantar fasciitis compared to electrical stimulationtherapy. A recent Systematical Review on Traditional Chinese Medicine (TCM) identified thatcupping therapy, along with acupuncture and acupressure, could be efficacious in treatingpain and disability in patients with chronic neck pain or chronic low back pain23⁾. In addition, cupping therapy has beenused in treating various painful disorders19^, 22⁾, including low back pain24^,25^,26^,27⁾,neck and shoulder pain28^, 29⁾, fibromyalgia30⁾, knee osteoarthritis31^,32⁾, and carpal tunnel syndrome33⁾. The results from this study add plantarfasciitis to the list. For all the outcome measurements, the cupping group did slightlybetter than the control group, although no statistically significant difference was foundbetween the two groups. This research supports the integration of cupping therapy intreating plantar fasciitis in physical therapy practice.

We found that dry cupping therapy and electrical stimulation therapy had a similar level ofeffectiveness in decreasing pain and improving function in patients with plantar fasciitis.Interestingly, the therapeutic mechanisms of dry cupping therapy may be different from thatof electrical stimulation therapy. Dry cupping therapy is believed to decrease pain by usingthe local negative pressure to promoting blood flow while electrical stimulation therapy bystimulating large-fiber sensory neurons and decreasing nociceptive inputs to central nervoussystem through the mechanisms of the gate control theory.

Cupping therapy can be performed using several different techniques18⁾. The two primary types are dry and wet cupping. Wetcupping, also called bleeding cupping, involves controlled bleeding18^, 25⁾, and hence maybe prohibited by the current physical therapy practice laws in the United States. Cuppingtherapy can also be achieved using various subtypes of techniques, including retention,moving, shaking, quick, and balance cupping25⁾. The vacuum required in cupping therapy for suction can be achievedusing fire-heated air, manual hand pump, or electrical pump14^, 32^, 34⁾. In our study, dry cupping with retention technique and manualhand-pump was selected because it was easy to administer with relatively constant dosage anddoes not require expensive equipment. However, it should be noted that wet cupping is themost studied cupping technique in the literature, followed by dry (retained) cupping15^, 16⁾.

Institute of Medicine’s Relieving Pain in America: a Blueprint for Transforming Prevention,Care, Education, and Research calls for a culture transformation to better prevent, assess,treat, and understand pain35⁾. TheBlueprint advocates that the clinicians should increasingly aim at tailoring pain care toeach person’s experience, and self-management of pain by the patients should be promoted.Dry cupping is an ancient healing art that is easy to learn and suitable for self-managementof pain. It does not require expensive equipment or a huge space to provide treatment forthe patient.

The limitations of the research project include convenience sampling and the small samplesize limited by our available resources. The convenience sampling significantly impacts thegeneralizability of the results. The subjects were mostly young volunteers, and the samplelacked diversity. In addition, double blindness was not possible to minimize subject andinvestigator biases. Future rigorous research with a larger sample size from physicaltherapy patients is necessary.

Acknowledgments

The authors thank DPT students Toby Gerez, Evan Wray, Joseph Osborn, and Adam Kaufman fortheir participation and contribution to the research project, and Vincent Ragozine, DPT, MS,for constructive discussions.

REFERENCES