Efficacy and safety of thread embedding acupuncture for chronic low back pain: a randomized controlled pilot trial

Low back pain (LBP) is a major health problem, with an estimated lifetime prevalence of up to 70–85% [1] and high treatment costs. Most patients with nonspecific acute LBP exhibit an unremarkable natural course. Nonspecific acute LBP generally presents for a brief duration and is self-limited, with an improvement in symptoms within 4 weeks. Subacute LBP is defined as LBP lasting for 4–12 weeks and generally improves with time, albeit in a gradual manner. However, the improvement can be limited and incomplete. A subset of acute LBP patients will develop chronic LBP. The treatment of chronic LBP (lasting for ≥ 12 weeks) is difficult, and the condition does not improve much over time [2]. Approximately 24–80% individuals who experience activity-limiting LBP report a recurrence at 12 months after onset [3]. One year later, approximately 10% patients with acute LBP are either not working or being compensated, and approximately 20% continue to experience clinical symptoms [4]. LBP is associated with substantial morbidity, with individuals reporting that most, if not all, aspects of their lives are significantly affected by chronic pain. Individuals with LBP are often dissatisfied with conventional forms of medical care, including medication, physical therapy, and exercise [5]. Therefore, several patients with chronic LBP are interested in complementary and alternative medicine.

Acupuncture is one of the most frequently used interventions for LBP [6]. A number of meta-analyses of randomized controlled trials evaluating acupuncture for LBP have already been published and have supported the efficacy of this treatment, which has also been proven as an effective supplement to other forms of conventional medical treatments for chronic LBP [7‐10].

Thread-embedding acupuncture (TEA) is a new subtype of acupuncture treatment developed from catgut-embedding therapy. In traditional Chinese medicine, catgut-embedding therapy has been used for the treatment of several diseases such as musculoskeletal pain, obesity, chronic urticaria, perimenopausal syndrome, and depressive neurosis [11]. Recently, suture thread was used instead of catgut, which is made from the natural fiber of sheep or goat intestine, in Korea. Although many studies on catgut-embedding therapy have been conducted in China, studies on TEA are lacking; only some case reports have been documented in Korea, and a well-designed clinical study examining the efficacy and safety of TEA is desirable. From this perspective, we designed a randomized controlled pilot trial to evaluate the efficacy and safety of TEA for chronic LBP. The findings of this pilot trial are expected to lay the foundation for a future large-scale randomized controlled trial.

TEA is a new acupuncture technique that involves the use of a specially designed device for the insertion of absorbable thread (extraneous substance) at an acupoint to provide continuous stimulation. In the early days in Korea, TEA was commonly used for cosmetic applications and obesity treatment [20]. Recently, KMDs have started using TEA for the treatment of various musculoskeletal diseases. There are many reports on TEA for musculoskeletal pain, including ankle sprain, patellar dislocation, and lumbar disk herniation [21‐23]. However, most of these reports described single cases, and there is no randomized controlled study to date.

In the present study, we evaluated the efficacy and safety of TEA for chronic LBP and found significant improvements in VAS, SF-MPQ, and ODI scores in a time-dependent manner in both TEA and acupuncture groups. These findings suggest that both TEA and acupuncture may be effective for pain control. Furthermore, the ODI was associated with a significant interaction between group and time, with the two groups exhibiting a different pattern of change at 8 weeks according to contrast analysis with Bonferroni’s correction. Considering that ODI is the most standard measurement for low-back-specific dysfunction, our findings suggest that TEA maybe more effective in improving the disability of patients compared with conventional acupuncture. Also more than 8 weeks of TEA treatment is required to achieve effects better than those of acupuncture.

Even if a patient with chronic LBP undergoes active treatment, improvement is very slow. In addition, patients may be reluctant to accept acupuncture treatment because it requires frequent visits to the doctor. TEA is performed once every 2 weeks and may provide somewhat better effects compared with conventional acupuncture treatment. If TEA can provide better effects with fewer visits compared with conventional acupuncture, it can also decrease the overall cost of treatment and save time.

Not many studies have investigated the mechanism of action of TEA, which is considered to act through both the acupuncture and the suture thread. The insertion process is similar for both TEA and acupuncture; however, in TEA, the suture thread remains inside the body for continuous biostimulation. Recently, it was reported that the embedded thread, which dissolves by slow hydrolysis in the tissue, may play a role as a long-lasting stimulator of collagen fiber formation through the downregulation of c-Jun N-terminal kinase (JNK) and matrix metalloproteinase (MMP)-9 activity [24].

We assumed that TEA can provide significant amelioration of chronic LBP by continuous stimulation of the core muscles and ligaments around the spine and abdomen. The core muscles play an important role in stabilizing the spine and are used in exercise therapy for chronic LBP. If chronic LBP persists for a long time, the muscles around the cervical and thoracic spine can also become weak. Accordingly, the erector spinae, trapezius, and levator scapulae should also be treated with muscles in the lumbar region. Therefore, we performed TEA using the core, back, and neck muscles, which resulted in similar effects with lesser visits compared with conventional acupuncture. The precise mutual relationship between the thread and surrounding tissues remains unclear because of the lack of previous studies, and further studies should evaluate the mechanism of action of TEA in more detail.

Although TEA is frequently used in clinics and hospitals for Korean medicine, there is lack of evidence regarding its safety. TEA is generally known to be safe. However, because it is more invasive than acupuncture and involves the insertion of a thread, the possibility of infection must be considered. In the present study, we tested for infection by performing hematological and biochemical tests at screening and 8 weeks after treatment initiation in both groups and at 2 days after the first treatment session in the TEA group. The findings at all time points were within normal limits, supporting the safety of TEA. Recently, tender, erythematous, subcutaneous nodules at the point where the catgut was embedded were reported and considered to be a foreign-body reaction [25]. Thread used in TEA is polydioxanone and has already been widely used as a suture thread [26]. Therefore, TEA seems safer than catgut-embedding therapy in the foreign-body reaction. Although two participants from the acupuncture group in the present study complained of itching on the low back, no serious adverse effects or skin problems were recorded for any participants. Therefore, our results suggest that TEA may be a safe procedure in 10 weeks. However, the long-term adverse events of TEA should be examined.

The present study has some limitations. Even though TEA exhibited similar results in a fewer number of visits compared with acupuncture, the precise underlying mechanism is not clear and needs to be clarified through additional research. Participants and practitioner had not been blinded in this study. Especially in the TEA study, it is difficult to develop a sham device for the purpose of blinding. First of all, a participant-blinded clinical trial is necessary for further study. Blinding participants by performing TEA without a thread can be an alternative. Inserting the needle after removing the thread is considered to produce participant blindness and evaluate the effect of the thread. However, this method cannot also blind practitioners and, therefore, cannot avoid high risk of performance bias. In this 10-week study, no adverse effects of TEA have occurred. However, we cannot be convinced that TEA is totally safe. TEA is still invasive and dangerous in terms of inserting threads. Further studies are needed on infection, hematological examination, foreign-body reaction to the thread, and neurovascular injury. In addition, factors that can affect results, such as participant’s expectation to the study participation or the allocated interventions, socioeconomic status and disease duration, were not measured. It is advisable to consider unmeasured confounders in a further larger-scale study. Also, as the present study is a pilot study, further large-scale studies are needed to demonstrate the exact efficacy and safety of TEA.

This pilot study suggested the possibility that treating chronic LBP using TEA may be safe and effective in the short-term. This result has provided basic data for a larger clinical trial on TEA for chronic LBP.