Studies that analyse the effects of mud therapy on function

Twelve studies that analyse the effect of mud therapy on functional capacity of the joint [8, 16, 17, 23–27, 30–33] were found (Table 1). The measurement tools used are the WOMAC [28] questionnaire and the Lequesne Algofunctional Index, which are recommended by the European League Against Rheumatism (EULAR) [29]. At least one of these measurement tools is used in each study. Of those that use WOMAC, we highlight the work done by Odabasi et al. [25], whose objective was to assess the effectiveness of mud therapy on patients diagnosed with knee OA. They divided the study population into a control group that followed daily pharmacological treatment and an experimental group (n = 32) to which a 45°C mud pack was applied for 30 min for five sessions a week for 3 weeks. The results indicated a 60% improvement in functional capacity maintained for 4 weeks after the end of the treatment; however, the methodological quality of the study indicates a moderate risk bias, as it did not use a randomized sample or controls and it did not indicate the possible dropouts during the follow-up of the study. Similar to this are the recent studies by Fraioli et al. [23] and Forestier et al. [17]. Both established a comparison between an experimental group that received mud pack therapy and a control group that continued with daily pharmacological treatment for knee OA. The Lequesne Algofunctional Index was used as the measurement tool for the first and the WOMAC questionnaire for the second. The results showed a significantly favourable improvement for the group that received mud therapy in comparison with the control group.

Fioravanti et al. [24], Cantarini et al. [30] and Mika et al. [16] carried out comparative studies on the effectiveness and tolerance of mud therapy in contrast to short wave therapy [24, 30] and physical exercise [16] with the objective of establishing a comparison of the effects gained with mud therapy and other frequently used techniques in physiotherapy. Fioravanti et al. [24] studied a sample of 72 subjects randomly divided into two groups: group 1 (n = 48), which had mud treatment, and group 2 (n = 24), which received short wave cycles. The results were satisfactory in both groups. Cantarini et al. [30] divided their sample into three randomly assigned groups (n = 74). The first group (n = 30) received mud treatment, the second group (n = 24) was treated with diathermia and the third group (n = 20) constituted a control group. Functional capacity was measured with the Lequesne Algofunctional Index and there were better results in group 1. Both studies presented quality methods with a low risk of bias, randomization, control of the subjects as well as a blinded researcher.

Of the studies that establish comparisons between different balneotherapy techniques and frequency of treatment, we highlight those by Cutovik et al. [31] and Evcik et al. [26]. Evcik et al. [26] divided a sample of 80 subjects into three groups. The first group took baths in thermal pools, the second received mud therapy and the third received 10 sessions of hot packs with a frequency of five sessions a week. The results showed a significant improvement regarding function for the three applied techniques; however, the group treated with mud therapy showed the greatest improvement. The necessary treatment period to obtain positive effects was the objective of the Vath et al. [27] study. The subjects (n = 296) were divided into two groups: both received the same treatment of mud therapy and thermal baths, but one group had treatment for 6 days and the other for 12 days. The results obtained were similar in both groups.

Finally, there were studies that showed the importance of the organic components of mud therapy to the improvement in functional capacity and pain. These studies applied the same intervention methodology in individuals with knee OA using enriched and impoverished mineral components in mud packs. The only limitations found were the lack of homogeneity in the distribution of the sample and its size.

Studies that analyse the effects of mud therapy on pain

There were 16 studies [8, 16, 17, 23–27, 30–37] that analysed the effects of mud pack therapy on perceived pain while also assessing the effect on function, and in some cases the influence on the need for medication [15, 38]. All the reviewed studies used a visual analogue scale (VAS) assessment of pain as the measurement tool (Table 2). The duration of the intervention ranged from 2 to 3 weeks. The studies’ main objective was to analyse the effects of mud therapy on pain, basing the methodological design on the establishment of a comparison of the benefits of a physiotherapy and balneotherapy treatment and where the previous therapy was applied but mud therapy was added [16, 31]. Others analysed perceived pain through a mud-based therapy and an invasive approach such as HA IA injection [8], through an association of mud therapy and drug therapy [36] or simply through a control group [17].

The study of Flusser et al. [32] showed an 11.07% improvement with the application of natural mud pack therapy compared with a 2.61% improvement obtained with the use of impoverished mud packs. The improvement was maintained during a 3-month follow-up period. On the other hand, Vath et al. [27] concluded that the duration of the intervention influences pain intensity. The perceived pain was less in individuals to whom the treatment was applied for 12 days than in those who received a 6-day application. This improvement has been related to specific changes found in biochemical markers that are involved in articular cartilage degeneration [33, 34].

Studies that analyse the effects on quality of life

We only found four articles that studied the impact of mud pack therapy on the quality of life of patients with knee OA [17, 26, 33, 39]. Unlike the previous reviewed variables, the measurement tools used were heterogeneous (Table 3). In a study of 349 subjects diagnosed with knee OA, Forestier et al. [17] estimated an improvement of 54.4% for the experimental group after 3 weeks of treatment compared with an improvement of 29.7% obtained by the control group according to the outcomes of the SF-36 (short form health survey) questionnaire that was used. Yilmaz et al. [39] studied a smaller group of subjects (n = 46) during a similar intervention period and using the same assessment scale. The improvements obtained were at least 10% in each dimension that constitutes the questionnaire. Fioravanti et al. [33] analysed in one of their studies the perceived quality of life for a subject with knee OA who receives mud pack therapy treatment. The subjects of the study (n = 80) were randomly divided into two groups (experimental and control) and the first received daily treatment for a total of 2 weeks. The results showed an improvement in the quality of life close to 30%. Finally, Evcik et al. [26] applied the Nottingham Health Profile (NHP) questionnaire to three study groups and obtained an improvement in pain and sleep dimensions in all the groups, showing better results in the group of subjects who received a treatment of mud pack therapy and thermal baths.