The Efficacy of Electromagnetic Diathermy for the Treatment of Musculoskeletal Disorders: A Systematic Review with Meta-Analysis

OBJECTIVE: This study aims to establish the effect of electromagnetic diathermy therapies (e.g., shortwave, microwave, capacitive resistive electric transfer) on pain, function, and quality of life in treating musculoskeletal disorders. METHODS: We conducted a systematic review according to the PRISMA statement and Cochrane Handbook 6.3. The protocol has been registered in PROSPERO: CRD42021239466. The search was conducted in PubMed, PEDro, CENTRAL, EMBASE, and CINAHL. RESULTS: We retrieved 13,323 records; 68 studies were included. Many pathologies were treated with diathermy against placebo, as a standalone intervention or alongside other therapies. Most of the pooled studies did not show significant improvements in the primary outcomes. While the analysis of single studies shows several significant results in favour of diathermy, all comparisons considered had a GRADE quality of evidence between low and very low. CONCLUSIONS: The included studies show controversial results. Most of the pooled studies present very low quality of evidence and no significant results, while single studies have significant results with a slightly higher quality of evidence (low), highlighting a critical lack of evidence in the field. The results did not support the adoption of diathermy in a clinical context, preferring therapies supported by evidence.


Background
Musculoskeletal disorders (MSDs) affect 1.71 billion people globally, with impressive financial costs for healthcare systems [1,2]. According to the WHO, the core strategy to reduce the constant rise of people suffering from MSDs is represented by rehabilitation [2]. The "Rehabilitation 2030: a call for action" initiative of the WHO further calls for ever greater integration of rehabilitation within health systems at all levels, both for communities and for hospital services [3].
Rehabilitation of MSDs is delivered by multi-professional teams. Interventions vary according to disorders and impairments; evidence-based treatments are not always common and shared, even within the same countries, where therapists perform different treatments to manage the same condition. However, non-specific rehabilitation interventions are common and performed in different countries. Among them, diathermy is used in different modalities by physicians in low-and middle-income countries as well as in high-and very-high-income countries for the treatment of MSDs [4][5][6].

Selection of the Studies
Two reviewers [JP and RB] independently screened the records for title, abstract, and full text using the software Rayyan [22]. Disagreements were solved with the consensus of the two reviewers, and a third author [SGL] was consulted in case of persistent disagreement.

Data Extraction
Two reviewers [RB and JP] extracted the data in a predefined excel sheet. Data were extracted regarding the study, methods, participants, interventions, outcomes, and notes.

Risk of Bias Assessment
'Risk of bias tool 1.0 was used to assess RCTs using the criteria recommended by Cochrane [23]. Two reviewers [RB and JP] independently assessed the risk of bias. A third reviewer [PP] was consulted in case of disagreement.

Measures of Treatment Effect
Standardized mean differences (SMD) with 95% confidence intervals (95% CI) were calculated for continuous data. Mean difference (MD) was calculated for pooled studies with the same outcome measure and non-pooled studies.

Certainty of Evidence
'GRADE handbook for grading quality of evidence and strength of recommendations' [24] and GRADEpro GDT Software (McMaster University and Evidence Prime, 2022) were used for assessing the certainty of evidence for the main outcomes of this review (i.e., pain relief and improvement in function).

Dealing with Missing Data
Where data were not extractable or not fully reported, corresponding authors were contacted. To retrieve data, when they were presented graphically, or with missing means, we used the methods proposed by Cochrane Handbook [25,26]. In the case of graphic data, we used the software "https://automeris.io/WebPlotDigitizer/ (accessed on 28 February 2023)" to extract the values. In the case of data presented as median and interquartile range or minimum and maximal value, the mean and standard deviation was calculated according to the method proposed by Wan et al. [27].

Data Synthesis
Data were summarized by MSDs. For each disorder, data were presented for the outcomes considered in this systematic review (i.e., pain relief, change in function, QoL, patientrated overall improvement, and adverse events). Where possible, the results of the studies were pooled according to the type of diathermy utilized in the intervention (e.g., SWD, MWD, CRET), considering similar comparisons to reduce a source of heterogeneity.

Results
The database search identified 13,323 records, and 79 extra records were identified through other methods. After the screening process, 69 reports of 68 studies were included. The full process has been synthesized in Figure 1. The 68 included studies considered 4892 patients affected by different MSDs. A certain degree of heterogeneity is evidenced in the studies regarding the types of proposed interventions. The diathermy with the highest occurrence was SWD, with 43 studies (63%) , and MWD had the second highest occurrence with 13 articles (19%) [72][73][74][75][76][77][78][79][80][81][82][83][84]. One article, Hammad 2019 [85], indifferently proposed SWD or MWD or hot packs under the label of thermotherapy as a treatment in addition to Kalternborn mobilization in patients with frozen shoulder.
We found 17 treated MSDs. The pathology most considered was OA, with 27 studies included in the review (40%), followed by LBP, with 12 studies (18%).
The risk of bias graphs ( Figure 2 and Supplementary File S2) show for the selection bias that 46% of the studies did not report clearly how the random sequence was generated, and 56% did not report the allocation concealment. Furthermore, 57% of the studies had a high risk of bias in the blinding of participants and personnel, due to the difficulties in blinding in rehabilitation studies. Also, the assessor blinding had a low risk of bias in about half of the studies (51%). The outcome data were provided with a low risk of bias in 72% of the studies. The study protocol was coherent with the outcome measures presented in the paper in 12 studies (18%), whereas 7% of the studies modified the outcomes reported in the study protocol, and 75% of the studies did not present a study protocol.
The risk of bias graphs ( Figure 2 and Supplementary File S2) show for the selection bias that 46% of the studies did not report clearly how the random sequence was generated, and 56% did not report the allocation concealment. Furthermore, 57% of the studies had a high risk of bias in the blinding of participants and personnel, due to the difficulties in blinding in rehabilitation studies. Also, the assessor blinding had a low risk of bias in about half of the studies (51%). The outcome data were provided with a low risk of bias in 72% of the studies. The study protocol was coherent with the outcome measures presented in the paper in 12 studies (18%), whereas 7% of the studies modified the outcomes reported in the study protocol, and 75% of the studies did not present a study protocol.
Cetin 2008 [41] reported no differences between the two therapies for the Lequense Index. Follow-up values are shown in Table 3. Three studies [30,40,41] evaluated the functional improvements comparing SWD and other physical agent therapies; 2 [30,40] of them were pooled (SMD −0.05, 95% CI −0.41 to 0.32, random-effects model) with non-significant results (p = 0.81) and I 2 = 6% (GRADE: Low), Figure 15. Cetin 2008 reported a significant improvement of function between pre-and PT within groups, but no differences were found between SWD and the other physical agent therapy considered for the Lequense index. The follow-up results of Atamaz 2012 [30] are reported in Table 3. Two studies [47,49] compared different energy doses of SWD in the treatment of knee OA. The data were pooled (SMD 0.50, 95% CI −0.17 to 1.17, random-effects model) with non-significant results (p = 0.15), and heterogeneity of I 2 = 38% (GRADE: very low), Figure 16. Clarke 1974 [36] provided only aggregate data and no p-value for the differences between SWD and sham SWD and for the comparison between SWD and ice application, so it was not possible to evaluate the effectiveness of the intervention. All the non-pooled comparison values of MD are presented in Table 3.  Table 2. Two studies [47,49] compared the treatment effects of different energy dosages (high energy dose compared with low energy dose) of SWD. The studies were pooled (SMD 0.16, 95% CI −0.34 to 0.66, random-effects model) with non-significant differences between the two groups (p = 0.54) and 0% of heterogeneity (GRADE: very low), Figure 9. Coccetta 2018 [86] compared CRET with a sham CRET treatment, but reported only graphically a significant reduction in pain intensity post-treatment, at short-and medium-term follow-ups for the VAS pain scale within groups. However, Cocetta 2018 did not report the results between groups. All the nonpooled comparison values of MD are presented in Table 2.                       aggregate data and no p-value for the differences between SWD and sham SWD and for the comparison between SWD and ice application, so it was not possible to evaluate the effectiveness of the intervention. All the non-pooled comparison values of MD are presented in Table 3.     aggregate data and no p-value for the differences between SWD and sham SWD and for the comparison between SWD and ice application, so it was not possible to evaluate the effectiveness of the intervention. All the non-pooled comparison values of MD are presented in Table 3.     aggregate data and no p-value for the differences between SWD and sham SWD and for the comparison between SWD and ice application, so it was not possible to evaluate the effectiveness of the intervention. All the non-pooled comparison values of MD are presented in Table 3.     aggregate data and no p-value for the differences between SWD and sham SWD and for the comparison between SWD and ice application, so it was not possible to evaluate the effectiveness of the intervention. All the non-pooled comparison values of MD are presented in Table 3.     Six studies [29,32,39,45,49,50] assessed the QoL level in patients with knee OA who underwent diathermy treatments. The pooled data of 2 studies [29,32] comparing SWD and sham SWD (SMD 0.55, 95% CI 0.20 to 0.90, random-effects model) showed a significant result (p = 0.002) in favour of SWD therapy, and no heterogeneity (I 2 = 0%). All the nonpooled comparison values of MD are presented in Table 4. Ovanessian 2008 [49] compared high-and low-energy SWD, and reported no difference between groups for the KOOS (Knee Injury and Osteoarthritis Outcome Score) QoL subscale.              Three studies [42,44,45] assessed the patient-reported overall improvement; 2 studies [42,44] comparing SWD and US therapy were pooled (SMD 0.03, 95% CI −0.30 to 0.36, random-effects model) with no significant differences between the interventions (p = 0.86), and no heterogeneity (I 2 = 0%). Cantarini 2006 [45] reported no differences between SWD and routine PT evaluated by an overall efficacy assessment (a scale from 0 to 4 points).
The GRADE assessment for the certainty of evidence for the main outcomes considered in the studies in patients with OA ranges from low to very low.
Two studies [52,55] compared SWD with sham SWD. They were pooled (SMD −1.47, 95% CI −2.95, 0.01, random-effects model) with non-significant results (p = 0.05) and I 2 of 95% (GRADE: very low), Figure 17. Two studies [53,54] [51,57] showed significant changes in favour of the control group, respectively: Maitland mobilization + hot packs + core stabilization at post-treatment (MD 0.60, 95% CI 0.23 to 0.97, random-effects model) and Graeco-Arabic massage at post-treatment (MD 2.50, 95% CI 1.50 to 3.50, random-effects model). In three studies [89][90][91], non-pooled data for pain relief showed significant important changes in favour of CRET. Specifically, non-pooled data for pain relief in Zati 2018's study [89] (Table 5). Gibson 1985 [56] assessed the effectiveness of SWD, placebo SWD (i.e., detuned SWD), and osteopathy. All the treatments reported an improvement within groups (p < 0.01) for VAS daytime and nocturnal pain score, both after treatment and at IT. A comparison between groups was not presented. Farrell 1982 [75] compared passive mobilization and manipulation with MWD plus isometric abdominal exercises and ergonomic instructions. The results for pain (mean subjective rating, from 0 to 10 points) were reported graphically and showed a trend toward pain reduction in both groups, with no significant difference between the two groups.
1.50 to 3.50, random-effects model). In three studies [89][90][91], non-pooled data for pain relief showed significant important changes in favour of CRET. Specifically, non-pooled data for pain relief in Zati 2018's study [89] highlighted significant changes in favour of CRET deep heating (MD −0.90, 95% CI −1.57 to −0.23, random-effects model) vs. superficial heating post-treatment. Non-pooled data for pain relief in Notarnicola 2017 [90] found significant changes in favour of CRET vs. Laser at Short-Term follow-up (MD −1.90, 95% CI −2.85 to −0.95, random-effects model), while Wachi 2022 [91] found significant changes in favour of CRET compared with sham CRET at post-treatment (MD −3.30, 95% CI −4.12 to −2.48, random-effects model) ( Table 5). Gibson 1985 [56] assessed the effectiveness of SWD, placebo SWD (i.e., detuned SWD), and osteopathy. All the treatments reported an improvement within groups (p < 0.01) for VAS daytime and nocturnal pain score, both after treatment and at IT. A comparison between groups was not presented. Farrell 1982 [75] compared passive mobilization and manipulation with MWD plus isometric abdominal exercises and ergonomic instructions. The results for pain (mean subjective rating, from 0 to 10 points) were reported graphically and showed a trend toward pain reduction in both groups, with no significant difference between the two groups.    [53,54] revealed significant changes in favour of the dynamic muscular stabilization technique group compared with SWD + ultrasound + lumbar strengthening exercises post-treatment. Moreover, non-pooled data for Ansari 2022 [57] showed significant improvement for the control Graeco-Arabic massage group (MD 3.80, 95% CI 0.73 to 6.87, random-effects model) compared with SWD post-treatment. Non-pooled data of three studies   [53,54] revealed significant changes in favour of the dynamic muscular stabilization technique group compared with SWD + ultrasound + lumbar strengthening exercises post-treatment. Moreover, non-pooled data for Ansari 2022 [57] showed significant improvement for the control Graeco-Arabic massage group (MD 3.80, 95% CI 0.73 to 6.87, random-effects model) compared with SWD post-treatment. Non-pooled data of three studies [51,56,90] [56] showed no significant changes in favour of any treatment groups at any time point (Table 6). Farrell 1982 [75] compared passive mobilization and manipulation with MWD plus isometric abdominal exercises and ergonomic instructions. An improvement in lumbar extension was reported for the manipulation and mobilization group (p < 0.05), while no other significative improvement in lumbar motion was reported. Wachi 2022 [91] compared CRET with sham CRET, calculating the differences in muscle time onset during manual muscle tests. The results showed a significant decrease in onset time in three out of four muscles in the CRET group.  Only the non-pooled data of the Durmus 2014 study compared the effects of diathermy + active exercises vs. only active exercises on the QoL, and did not find significant changes in favour of any of the two groups (Table 7). The GRADE assessment for the certainty of evidence for the main outcomes considered in the studies in patients with LBP ranges from low to very low.

Shoulder Tendinopathies (STN)
Six studies [58,59,[76][77][78]92] evaluated the efficacy of diathermy for treating STN. Two studies utilized SWD, 3 studies used MWD, and 1 utilized CRET. All 6 studies assessed pain relief. Non-pooled data for pain relief in Yilmaz Kaysin's 2018 study [58] [77] reported significant changes in favour of the control subacromial corticosteroid injections group, compared with MWD at long-term follow-up (MD 9.50, 95% CI 1.70 to 17.30, random-effects model). Non-pooled data for pain relief in Jimenez-Garcia 2008 [59], Akyol 2012 [76], and Avendaño-Coy 2022 [92] did not show any significant changes in favour of any considered groups at any time point (Table 8).   Akyol 2012 and Avendaño-Coy 2022 assessed QoL improvement, but did not underline any significant changes in favour of any considered groups at any time point (Table 10). The GRADE assessment for the certainty of evidence for the main outcomes considered in the studies in patients with STN ranges from low to very low.

Frozen Shoulder (FS)
Three studies [60,61,85] evaluated the effect of diathermy in the treatment of the frozen shoulder. Two studies [60,61] compared SWD with other interventions, while Hammad 2019 [85] evaluated the effect of adding diathermy treatment (MWD or SWD) to a manual therapy intervention (i.e., Kalternborn mobilization). Only Guler-Uysal 2008 [60] assessed patients' pain relief post-treatment and non-pooled data highlighted significant changes in favour of the control Cyriax treatment + other interventions (MD 12.10, 95% CI 0.03 to 24.17, random-effects model) compared with SWD + hot packs + other interventions (Table 11). In the same study, the authors assessed improvement in function and non-pooled data showed significant changes, also in this case, in favour of the control group (MD −21.60, 95% CI −33.93 to −9.27, random-effects model). In contrast, non-pooled data for improvement in function post-treatment in Hammad's 2019 study showed significant changes in favour of diathermy + Kaltenborn mobilization (MD −51.80, 95% CI −54.94 to 48.66, randomeffects model) compared with only Kaltenborn mobilization. In addition, non-pooled data for improvement in function in Leung's 2008 study [61] showed no significant changes post-treatment and at short-term follow up comparing SWD + stretching exercises vs. hot packs (+ stretching exercises). In contrast, the same study presented significant changes in favour of the SWD + stretching exercises group, comparing it with only stretching exercise post-treatment (MD 21.70, 95% CI 9.47 to 33.93, random-effects model) and at short-term follow-up (MD 17.50, 95% CI 1.76 to 33.24, random-effects model) ( Table 12).
The GRADE assessment for the certainty of evidence for the main outcomes considered in the studies in patients with FS is very low.

Carpal Tunnel Syndrome (CTS)
Three studies [62,63,79] proposed The GRADE assessment for the certainty of evidence for the main outcomes considered in the studies in patients with CTS ranges from low to very low. The GRADE assessment for the certainty of evidence for the main outcomes considered in the studies in patients with FS is very low.

Carpal Tunnel Syndrome (CTS)
Three studies [62,63,79]       The GRADE assessment for the certainty of evidence for the main outcomes considered in the studies in patients with CTS ranges from low to very low.

Lower Limb Tendinopathies (LLT)
Two studies [80,81] treated LLT with diathermy (MWD). Giombini 2002 [80] included athletes with Achilles and patellar tendinopathies, while Cheng 2018 [81] included athletes with patellar tendinopathies. In this contest, non-pooled data from Giombini 2002 showed significant changes post-treatment in pain relief in the MWD group (MD −2.20, 95% CI −3.09 to −1.11, random-effects model) compared with ultrasound therapy. In contrast, Cheng 2018 showed significant changes in favour of the control extracorporeal shock wave therapy (MD 3.70, 95% CI 3.12 to 4.28, random-effects model) compared with MWD + acupuncture + ultrasound therapy (Table 13). Non-pooled data for improvement in function in the Cheng 2018 study did not find significant important changes in any of the considered groups (Table 14).  The GRADE assessment for the certainty of evidence for the main outcomes considered in the studies in patients with LLT is very low.

Neck Pain (NP)
Two studies [64,82] evaluated the effect of diathermy in the treatment of NP: Dziedzic 2005 [64] with SWD, and Ortega 2013 [82] with MWD. Neither of the two studies showed significant differences in favour of any groups considered, at any time point, and in any outcomes assessed: pain relief, improvement in function, and quality of life (Tables 15-17). Dziedzic 2005, and Ortega 2013 reported no differences in the patient-reported overall improvement for the proposed interventions.  The GRADE assessment for the certainty of evidence for the main outcomes considered in the studies in patients with NP ranges from low to very low.
Verma 2012 reported significant relief in both groups (SWD + active exercises vs. taping + active exercises) but did not compare the results of the two interventions. Moreover, this study showed a significant improvement in function in both groups without comparing the two interventions. Non-pooled data of the Albornoz-Cabello 2020 study highlighted significant changes post-treatment in favour of monopolar dielectric radiofrequency + active exercise in pain relief (MD −53.00, 95% CI −59.22 to −46.78, random-effects model), and improvement in function (MD 22.00, 95% CI 15.45 to 28.55, random-effects model) compared with only active exercise (Tables 18 and 19).
The GRADE assessment for the certainty of evidence for the main outcomes considered in the studies in patients with PFP is very low.

Temporomandibular Joint (TMJ)
Two studies [66,67] treated TMJ problems with SWD and compared it with other treatments. Specifically, Talaat 1986 [67] did not show significant changes in pain relief comparing SWD vs. ultrasound therapy, while they showed significant changes posttreatment in favour of SWD by comparing it with treatment with a tablet of methocarbamol + acetyl salicylic acid (MD −1.12, 95% CI −1.49 to −0.75, random-effects model) (Table 20). Gray 1995 [66] compared different treatments, namely SWD, Megapulse, US therapy, laser therapy, and a placebo treatment. The reported results were a mix of patient-reported improvement and non-specified objective measurements. Data were reported in absolute and relative frequencies. No significant differences were retrieved among the four interventions, but all four treatments showed a significant improvement compared to the placebo treatment.
The GRADE assessment for the certainty of evidence for the main outcomes considered in the studies in patients with TMJ is very low.

Delayed Onset of Muscular Soreness (DOMS)
Two studies [94,95] utilized diathermy to treat DOMS. Visconti 2020 [94] assessed the effect of CRET for the treatment of DOMS in athletes, while Nakamura 2022 [95] treated healthy subjects with DOMS with CRET comparing it with no treatment. Notably, nonpooled data in Visconti's 2020 study showed no significant effect in either group on pain relief (Table 21). Futhermore, they reported no differences in the global impression of change (p = 0.638) among the CRET, Sham CRET, and Massage groups. Nakamura 2022 showed no significant changes comparing CRET vs. no intervention in improvement in function (Table 22).  The GRADE assessment for the certainty of evidence for the main outcomes considered in the studies in patients with DOMS is low.

Humerus Fractures
The study of Livesley 1992 [68] compared the effect of SWD combined with a standard physiotherapy treatment (specific contents were not described), with sham SWD combined with the same standard physiotherapy treatment. This study showed no differences in pain relief and improvement in function between the two interventions.

Ulnar Nerve Entrapment (UNE)
Badur 2020 [69] compared SWD with sham SWD in patients with UNE. No significant results in favour of any of the groups were found in the considered outcomes: pain relief, improvement in function, and QoL (Tables 23-25).   The GRADE assessment for the certainty of evidence for the main outcomes considered in this study in patients with UNE is low.
The GRADE assessment for the certainty of evidence for the main outcomes considered in this study in patients with LE is low.

Ankle or Foot Sprain
The study of Pasila 1978 [71] compared two different devices administering pulsed SWD therapy with sham SWD treatment. No significant differences were reported among the three interventions (adduction and abduction strength of the forefoot, ankle range of motion) except for the gait impairment score, for which one pulsed SWD machine (Diapulse) was significantly more effective in solving gait impairment.

Lower Limb Acute Muscle Injury (LAMI)
Giombini 2001 [83] compared the effect of MWD and US therapy in subjects affected by LAMI at different muscles of the lower limbs (i.e., biceps femoris, adductors, quadriceps, and gastrocnemius). Non-pooled data of pain relief in LAMI (Table 28) reveals significant effects in favour of MWD post-treatment (MD −2.20, 95% CI −2.90 to −1.50, randomeffects model). The GRADE assessment for the certainty of evidence for the main outcomes considered in this study in patients with LAMI is very low.

Tension-Type Headache (TTH)
Georgoudis 2017 [84] investigated the effect of myofascial release, MWD, stretching, and acupuncture versus stretching and acupuncture in patients with TTH. The authors reported no time*treatment interaction on VAS average. A pre-post improvement for pain relief (VAS average) was graphically reported for both groups.

Total Knee Replacement (TKR)
García-Marín 2021 [96] studied TKR post-operative pain. All three groups underwent usual physiotherapy (active mobilization, strengthening, and walking), and then one group underwent CRET while the other performed sham CRET. No significant results in favour of any of the three groups were found in the considered outcomes: pain relief, improvement in function, and QoL (Tables 29-31).   The GRADE assessment for the certainty of evidence for the main outcomes considered in this study in patients with TKR is low.

Discussion
This systematic review aimed to evaluate the effectiveness of electromagnetic diathermy for treating MSDs to reduce pain and improve function. The role of diathermy within treatment protocols was found to be very varied. It was proposed as a stand-alone therapy, especially when compared with sham intervention, as a component of multimodal treatment, or even considered within the usual care intervention. Consequently, diathermy was proposed within the experimental and control groups.
Diathermy was used as a treatment in 17 different MSDs. Both acute and chronic conditions were treated, based on the positive effect that thermotherapy can add to the treatment of these conditions [97,98]. However, in seven conditions only a single study was performed to prove the effectiveness of therapy. In only five MSDs, three or more studies were included. This limits the possibility to provide final conclusions on the topic.
In those MSDs where only few studies could be pooled, high levels of heterogeneity were retrieved, even if the manageable sources of heterogeneity were considered. This can represent a sign of deficiency in the study conduction of some of the primary studies.
Other authors have performed systemic reviews on diathermy in MSD treatment. Contrary to our results, Wang et al. [17] reported the efficacy of SWD against sham or no intervention in patients with knee OA for pain relief. It is worth pointing out that, in the meta-analysis by Wang et al., studies that did not have a placebo or no treatment as a control intervention were aggregated (Cetin 2008 andCantarini 2006 [41,45]). In our meta-analysis, on the other hand, only the comparison of SWD versus placebo or sham was considered. We also included our major source of heterogeneity (Fukuda 2011 [32]), removing which would have changed the I 2 from 64% to 0%, but would not have changed the pooled result. In addition, Wang et al. combined the placebo and no-treatment groups, as in Fukuda 2011, whereas we did not consider them two different interventions.
Other reviews [18,99] report a possible efficacy of CRET for pain relief and improvement in function in a mixed population, also including patients with MSDs. Their results should be interpreted considering the different study designs included (e.g., cases series and non-RCT studies), as well as the wide choice of outcome indicators and the lack of an assessment of the certainty of the evidence.
This study is the first systematic review that has assessed the effect of different types of electromagnetic diathermies on MSDs. Even if the pathologies, outcome, and the different types of diathermies considered create a huge number of results, the adopted methodology, and the methods of conducting were used to provide a confident response.
It is well known that therapies based on heat, including electromagnetic diathermies, are widely adopted all around the world [4][5][6], but the underlying evidence supporting their adoption is not so strong. Clinicians should focus on therapies supported by stronger evidence and use diathermies when-through their evaluation-benefits could be produced by heat.
Different studies included in this review provide clear, reliable, and encouraging results supporting diathermy treatments. However, the results of these studies should be confirmed by other trials, with large sample sizes and appropriate study designs. This review has some limitations; it did not provide a sensitivity analysis of the results. This is because the wide number of studies and pathologies included did not allow for such analysis. Further studies should investigate the specific pathologies and perform this analysis. Another limit of this review is that it did not show a strong clinical implication, even if in the treatment of knee OA meta-analysis results showed clearly that SWD is not effective. In some of the MSDs where more studies were retrieved, the unclear use of diathermy treatments with disparate treatment did not allow an extensive pooling of study results. Moreover, in other MSDs this review highlights the lack of evidence, with only single studies that provide limited results.

Conclusions
In conclusion, the findings of our review are influenced by the scarce quality of evidence. Further studies should perform trials with a larger sample size, experimental interventions based on diathermy as a stand-alone therapy to reduce the complexity of multi-approach protocols, control interventions defined according to MSDs guidelines, and a reduction of sequence generation and allocation bias.
The studies published up to now, even if providing a low quality of evidence, do not allow us to suggest the use of diathermy in clinical settings or its wide implementation within rehabilitative protocols. Indeed, there is no strong evidence that diathermy is preferable to placebo/sham intervention or other interventions for treating MSDs, even if in some specific cases diathermy showed significant results.