Treatment of gonarthrosis with Hirudo Medicinalis (medical leech): How does the therapy affect the sensation of pain and the mechanical touch threshold?
Gonarthrosis is one of the most common chronic diseases in the western world. The prevalence is over 10% among those over 55; a quarter of these are severely affected (Peat et al. 2001). The recommended therapy for gonarthrosis consists of a combination of non-pharmacological and pharmacological therapy options (Jordan et al. 2003). The group of NSAIDs (non-steroidal anti-inflammatory drugs) is used most frequently. However, side effects can occur especially in long-term therapy (Seed et al. 2009). It therefore makes sense to look for new treatment options.
These include treatment with Hirudo Medicinalis (medical leech), the effectiveness of which has been demonstrated in several studies using validated pain and function questionnaires (Michalsen et al. 2001; Michalsen et al. 2003; Andereya et al. 2008).
On the other hand, the specific mechanisms by which the effectiveness of leech treatment is mediated are unclear. In this study, it was therefore specifically investigated how the treatment of knee osteoarthritis with leeches affects the pain, vibration and touch sensation on the affected joint.
Methods / study design
The study was carried out as an application observation, in which only the routine work in the study center was documented. Since this was a pilot project in which the first data on the topic was to be generated, there was no division into therapy and control groups and therefore no randomization. The aim of the study was first to describe phenomena that arise from leech therapy and were measured with the instruments described below.
The study center was the Rheumatism Center Middle Hesse in Bad Endbach. This clinic has many years of experience in the treatment of rheumatological and orthopedic diseases.
42 patients with clinically and radiologically proven gonarthrosis participated in the study. Patients of both sexes were included
▶ between the ages of 40 and 85
▶ with a body mass index <35 kg / m2
▶ with bilateral gonarthrosis according to the criteria of the American Society of Rheumatology (Altman et al. 1986)
▶ with an X-ray arthrosis stage II – III according to Kellgren and Lawrence
▶ with an indication for leech therapy in accordance with the treating doctor
▶ with knee pain on most days of the past three months
Patients with secondary forms of osteoarthritis, severe comorbidity, systemic corticoid medication, existing anticoagulation or hemophilia have been excluded.
Main target criteria
The main goal criteria were changes in the Pressure Pain Threshold (PPT), the Mechanical Touch Threshold (MDT) and the Vibration Detection Threshold (VDT). These methods are subtests taken from the QST (Quantitative Sensory Testing) battery of the German Research Network for Neuropathic Pain (DFNS) (Rolke et al. 2006a, 2006b).
Pressure pain threshold PPT
The pressure pain threshold was measured with an algometer (Somedic AB, Hörby, Sweden). The metal stamp of the algometer has a contact area of 1 cm² and was placed on the skin at a right angle with constantly increasing pressure. Initially, the test subjects registered the touch and, in the coming course, increasing pressure. As soon as this pressure was felt to be painful, the test persons actuated a button attached to the measuring device, whereupon the measurement was stopped. This test was carried out at five different locations on both knees and on the palms of the hands.
Mechanical contact threshold MDT
The MDT was measured with so-called fiberglass hairs of different diameters, calibrated by Frey Härchen (Somedic AB, Hörby, Sweden), which are attached to a plastic handle. They have been specially developed to exert a defined pressure on the skin area in order to determine the intensity at which a touch on the surface of the skin was perceived. This measurement was carried out at two different locations on both knees and on the hands.
Threshold of vibration sensation VDT
The VDT was determined using a conventional Rydel-Seiffer tuning fork as used in neurology. Scaled weights are attached to the two jaws of the tuning fork, which are set in motion by the vibration of the tuning fork. The normal value is 8. If the sensation of vibration is reduced, it is lower. This tuning fork was vibratingly placed on the bones of the wrists (processus styloideus ulnae) and on the kneecaps. Normally, the subjects perceived the vibration for a certain period of time. As soon as they no longer felt vibrations, they were obliged to tell the examiner.
The WOMAC (Western Ontario and McMaster Universities Arthritis Index) is a specific questionnaire to be filled in by the patient with 24 questions, which determines the patient's state of health in the three directions of pain, joint stiffness and movement restrictions (function) and has been adapted for the German-speaking area ( Stucki et al. 1996; Bellamy et al. 1988).
Each question should be answered by the patient using a numerical analog scale from 0 to 10 (none - extreme). In order to be able to assess the pain on both knees separately, the patients were presented with two 10 cm long visual analog scales (VAS). The patients were instructed to place a cross at the point on the line that represented the pain at the respective knee (0cm - no pain, 10cm - most pain imaginable).
The frequency and amount of pain medication, as well as any medication that may be required, were taken from the study center patient files.
In addition, it was to be determined whether - due to the gonarthrosis - there was a distorted perception of the patient's knee pattern and a change after the leech therapy could be determined. For this purpose, each patient was asked to select one of eight different standard drawings of the right or left extremity, which most closely reflects their subjective size perception of the knee. The circumference of the knees was then measured using a tape measure.
Course of study
After checking the inclusion and exclusion criteria and the information provided by the doctors at the study center, the potential study participants were given test information and a declaration of consent in writing (Day -3).
On day 0, the study participants had to answer the questionnaires (WOMAC, VAS, knee diagram). The measurements were then carried out using the instruments described above. Finally, the knee diagram was presented to the patient and explained, and the circumference of the knees was measured. The leeches were then treated on the more affected knee. On day 7 after the treatment, the test subjects appeared for the second measurement and questioning. They were again given the questionnaires mentioned above and then the corresponding measurements were carried out.
The leech treatment was carried out in the rooms of the Rheumatism Center in Central Hesse. It was carried out in the form of a single local application of 3-5 leeches (Hirudo medicinalis) on the knee of the more painful side.
The leeches were placed in the area of the affected painful joint. The treatment was done while sitting or lying down. The relevant places had been marked by a doctor in consultation with the patient.
The leeches were removed from the leech container manually by trained personnel (using tweezers) and attached, gloves were always worn. The spontaneous drop of the gel was always waited for, this took an average of 20 to 60 minutes. The fallen leeches were disposed of by the staff in a designated container. First the bite wounds were covered with sterile swabs. In connection
an association was created on it. The next morning, the patients introduced themselves to check the wound and to change the dressing.
All evaluations were based on the intention-to-treat principle, i.e. H. Patients who were included in the study were included in the evaluation, regardless of whether they were treated according to the protocol or not and whether they provided data at all times of the survey or not.
Sensitivity analyzes also included evaluations based on the per-protocol population, i.e. H. of all patients who received a single leech therapy and had completed the main examination after 6–8 days.
Changes in the main and secondary target criteria were analyzed using multiple regression models in which expectations and gender were classified as factors and age as well as the respective baseline value entered the model as linear covariates.
A total of 42 patients aged 70.4 ± 9.8 years were enrolled in the study. The oldest participant was 84 years old, the youngest 49 years. Two thirds of the patients were female. A third of the patients were treated on an outpatient basis, the others inpatient treatment. Two thirds of the subjects received additional treatments during the observation period. Physiotherapy (59.5%) and treatment with clay (28.6%) predominated here. Furthermore, two thirds of the subjects took pain medication during the course of the study. Side effects occurred in five patients (11.9%). There was excessive itching, severe reddening and swelling of the treated areas, but at the latest one week after the treatment, the symptoms improved considerably.
As expected, the touch threshold in the control area, the hands, did not change. Above the kneecap and above the pain maximum, however, there was a decrease in the contact threshold, which was significantly stronger on the more painful knee than on the less painful one. Above the pain maximum, this decrease reached the level of significance.
With regard to the pain threshold, a reduction was found in almost all test areas, although the level of significance was never reached with one exception (on the hand of the less affected side). The vibration sensation threshold increased significantly on both wrists and on the kneecap on the less affected side. In contrast, there was no change in the knee on the more affected side.
Pain and function
After leech therapy, there was a significant improvement in two of the three WOMAC indices (pain and daily activity) and the global index, and a non-significant improvement in stiffness. In the more painful knee, there was a significant reduction in pain measured by VAS from 5.4 to 3.0. In contrast, no change was found on the less painful knee. Taking the drugs ASA (acetysalicylic acid) and ibuprofen showed no change in the comparison of the values before and after the therapy. In contrast, the drugs Diclofenac and Novalgin were taken more frequently.
Knee circumference and knee diagram
The treated knee was perceived as thicker than the untreated knee in the side comparison before and after therapy, so the subjective extent of the more painful knee before therapy was 1.4 (± 1.6) points, that of the less painful knee was 1 , 0 (± 1.5) points. After treatment with leeches, the perceived extent decreased slightly to 1.0 (± 1.6) or 0.5 (± 1.8) points. Both knees were therefore felt to be slightly thinner after the therapy. The actual size of the knee did not change.
This is the first study to collect detailed neurological data on the possible mechanisms of action of leech treatment for gonarthrosis. Although these are only pilot data, the results allow the conclusion that a single leech treatment in gonarthrosis patients can change the touch thresholds. The lack of a control group limits the meaningfulness of the results found, as well as the fact that the majority of the study participants have received accompanying treatments and the short observation period of only seven days.
A reliable clinical assessment of the effects found is also difficult because there are still no reference data for the measured values on the knee to check the validity of the data.
However, the small number of missing values and the good reliability of the measurement methods in themselves suggest that the methods chosen are suitable for validly recording changes in connection with leech therapy and thus contribute to an explanation of the effect of leech therapy.
The distinctive ability of leeches to influence blood clotting has long been known. The hirudin formed in the salivary glands of the egg is responsible for this. In this context, leeches have traditionally been used in thrombotic occlusion and stroke in many medical systems around the world. Since the hirudin can be synthesized pharmacologically, the outstanding anticoagulant effect of the hirudin has been proven in a large number of studies. Hirudin and related advancements are now firmly established in angiology and cardiology for anticoagulation.