Zaid Al-Boloushi, Eva Maria Gómez-Trullén, Mohammad Arian, Daniel Fernández, Pablo Herrero, Pablo Bellosta-López
BMJ Open; July 2020;10:e038033. doi:10.1136/bmjopen-2020-038033 [free open access]
Objectives To compare the effectiveness of dry needling (DN) versus percutaneous needle electrolysis (PNE) for improving the level of pain, function and quality of life (QoL) of patients suffering from plantar heel pain (PHP) provoked by myofascial trigger points.
Design A prospective, parallel- group, randomised controlled trial with blinded outcome assessment.
Setting A single treatment facility in the State of Kuwait.
Participants 118 participants were screened for eligibility. Of these, 102 participants were enrolled (30 men (49.5±8.9 years) and 72 women (48.1±8.8 years)) and 68 of them completed the trial.
Interventions Two parallel groups, one study arm received DN and a stretching protocol whereas the other arm received percutaneous needling electrolysis with a stretching protocol.
Outcome measures. The primary outcome measure was the Foot Pain domain of the Foot Health Status Questionnaire, with 13 questions related to foot health- related domains. Secondary outcome measures included the 0–10 numerical rating scale pain visual analogue scale (VAS) scores, performed before and after each treatment session. In addition, QoL was measured using the EuroQoL-5 dimensions. All measurements were taken at baseline, at 4, 8, 12, 26 and 52 weeks.
Results Foot Pain domain improved at all time points for DN group (p<0.001; 29.7 (17.8 to 41.5)) and percutaneous needling electrolysis group (p<0.001; 32.7 (18.3 to 47.0)), without significant differences between groups. Pain VAS scores decreased at all time points for both DN (p<0.001; −2.6 (−4.0 to −1.2)) and percutaneous needling electrolysis group (p<0.001; −3.0 (−4.5 to −1.6)). QoL improved at 4 weeks for both DN (p<0.01; 0.15 (0.5 to 0.25)) and percutaneous needling electrolysis group (p<0.01; 0.09 (0.01 to 0.17)) and at 8 and 52 weeks for the PNE group (p<0.01; 0.10 (0.02 to 0.18)), with significant differences between groups for the QoL at 52 weeks (p<0.05; 0.10 (0.01 to 0.18)). There were two small haematomas in the PNE group and one in the DN group. No serious adverse events were reported.
Conclusions Both PNE and DN were effective for PHP management, reducing mean and maximum pain since the first treatment session, with long lasting effects (52 weeks) and significant differences between groups in the case of QoL at 52 weeks in favour of the PNE group.
Trial registration number NCT03236779.
This group, from Kuwait and Spain, report a thorough RCT assessing the effect of PNE on PHP.
I find the title a bit misleading as it states “Comparing two dry needling interventions …” but that is not what it does. In fact both groups received the same protocol of stretching and DN; the difference between the groups was the addition of PNE, or not.
So first, let’s talk a bit about PNE. There are a number of papers reporting the use of PNE for either tendinopathies, or MTPs. I reviewed one of these in my book: Fernández-Rodríguez, et al in 2018, reported an RCT of PNE v placebo, for chronic PHP. The active treatment was significantly better than sham at 1 week after treatment and the benefits continued to increase at 3- and 6-month follow-up. The authors hail this as evidence of a tissue-healing effect, beyond short-term analgesia.
The rationale for using PNE, described by all the papers I have seen, is for the small galvanic current to cause local electrolysis and so to induce a localised inflammatory response, which will then go on to become a healing response. This makes sense where the pathology is a tendinopathy – a degenerative state, or a stalled healing response following earlier injury – but I don’t understand the logic of applying the same approach to MTPs as some of the studies did, including this one.
Commonly, ultrasonic guidance is used to locate the PNE precisely. As far as I can tell, this study is the only one applying the PNE during active needling, without US guidance.
This study seems to have been well designed and thoroughly carried out. A range of OCMs were assessed by a blinded clinician, sample-size calculations were performed with regard to minimally important difference, and appropriate statistics applied. Five different muscles in the foot and calf were explored for MTPs and their use documented. Subjects received four sessions at weekly intervals and outcomes were assessed at intervals between the start and week 52. In spite of all this, no significant difference was seen between the two groups. Adding PNE to the DN gave no additional benefit.
The authors speculated that this may be due to a very large dropout rate, which undermined the power of the statistics. There were indeed many dropouts – during the 4-week treatment period 9 or 51 in the DN group and 14 of 51 in the PNE group – and during the follow-up period 4 and 7 respectively – so only 68 of the original 102 recruits completed the course. It was noted that the earlier dropouts were all because of the “inability to withstand the pain of the needling”.
I do find it interesting that this issue is framed in terms of the patients’ “inability”. The style of needling used here was Hong’s technique; the paper describes it thus:
The chosen technique … consists of a rapid needle entry and exit (fast in/fast out), in order to obtain a local twitch response, lasting 5 s employing a rhythmic movement at approximately 1 Hz/s (five entries).
I have seen Professor Hong demonstrate his technique and I find the drop-out rate entirely understandable. What mystifies me is why anyone would choose to use this approach, when comparable results are obtainable from more humane techniques.
I also need to question the paper’s conclusion that: “Both PNE and DN were effective for PHP management…”. It is true that significant improvements were recorded in most of the OCMs, during the 4 weeks and sustained up to 52 weeks. Although, given that PNE seems to have made no difference, surely ‘DN was effective’ would be more accurate. However, there was no untreated control group, so the improvements seen could have been due to other factors (natural remission, regression to the mean, Hawthorne effect, etc). Sadly, the only safe conclusion here is that adding PNE in this context gave no added benefit.