All patients gave written inform consent and approval was obtained by local ethics committee. This is a single centre cross sectional, prospective study with inclusion starting from 2007 until 2009, evaluating the efficacy of a standardized protocol of continuous pressure using the MyoDK device for treatment of LE.

Description of the population enrolled: Thirty patients aged 18 to 75, with diagnostic epicondylalgia, presenting at the physical medicine clinic within a period of one year and willing to participate were eligible for a possible inclusion in the study.

Chronic epicondylalgia was defined as pain at the epicondyle insertion of the ECRB either at rest, under palpation or at resisted contraction, for at least 12 weeks (in duration since first symptoms).

Our Exclusion Criteria were: Patient undergoing a different form of physical treatment at the time of enrollment, mild to severe cognitive impairment, non-French speaker, inability to comply with the follow-up, inability for the patient or their legal representative to provide informed consent.

Standardized continous pressure protocol: Treatment was administered by a physiotherapist or a medical doctor. A progressively increasing pressure using MyoDK dynamometer was applied to the epicondyle insertion of the ECRB until the pain pressure threshold (PPT), defined as unbearable pain was reached. The PPT minus one third of its value was then sustained for 90 seconds. The common insertion and the bulk of ECRB and ECB were treated.

The process was repeated 10 times to reach a total treatment time of 20 minutes. The pressure applied started at 0.5kg/100mm² and the PPT was usually reached after 3 seconds at 1.5 kg/100mm² with 0.5kg/100mm²/s increments. The initial PPT was used as a reference as the minimal pressure to reach and to surpass in following visits. The patients received treatment once a week for a total of 6 treatment sessions.

Dynamometer: The MyoDK is a medical device that can quantify the amount of pressure (kg/100mm²) applied onto a patient’s body using a dynamometer. The Dynamometer is located directly on the divide between the physician and the patient, [Table/Fig-1] with practitioner’s body weight used as the pressure source.

[Table/Fig-1]:

Dynamometer

Outcome measures: Our primary outcome measure was the difference in the pain during activities the last 2 days between the patient’s first clinic visit and his last visit at the end of the treatment period at 6 weeks.

For each evaluation of pain, Visual Analoguous Scale (VAS) was used and graded from 0 to 100, 0 representing “no pain” and 100 “the worst pain imaginable”.

Primary outcome: Pain by VAS during activities evaluated patient global pain during last 48 hours on activities with VAS Pain Scale.

Secondary outcome measures: Number of patient lost to follow-up, Pain by VAS under pressure evaluated pain during the application of initial PPT at the insertion of ECRB.

Pain by VAS during contraction evaluated pain during a maximal hand griped resisted contraction, VAS Handicap evaluated fonctional limitation on daily living evaluated by the patient graded from 0 to 100, 0 representing no fonctionnal limitation et 100 maximal fontionnal limitation. Our null hypothesis was that there will be no difference in the patient’s VAS during activities between their first and last clinic visit at 12 weeks.

Data regarding demographics, activity level, patient’s history, previous treatment received were collected upon first clinical encounter. VAS was collected at the first patient visit, at 3 weeks and at 6 weeks. The need to switch to another treatment modality was assessed at the final follow- up visit.

Data analysis was completed using SYSTAT^® 9 for Windows^®.

Results will be expressed as a mean for continuous variables (VAS pain score at each time point, age, BMI, height, weight) and as a percentage for categorical variables (gender, laterality).

To assess a difference in our primary outcome measure, we used a paired T-test comparing the mean of the differences between the initial VAS and VAS at 3 and 6weeks. A value of p<0.05 was considered statistically significant.

During a one year period, we enrolled 30 patients, 2 patients were lost to follow-up between their initial visit and their 6 week visit and were not included in the statistical analysis. The mean age was 47.3 (ranging from 30 to 64), mean BMI was 25.2 (ranging from 19 to 37.3). Twenty-three (82.1%) were male, 26 (92.8%) were affected on the right side and 24 (85.7%) were affected on their dominant side [Table/Fig-2]. VAS, Handicap, PPT at the initial visit, 3 weeks and 6 weeks is shown in [Table/Fig-3]. The results of our comparison between endpoints are summarized in [Table/Fig-4]. No patients needed or asked to be switched to another treatment modality.

A recently updated meta-analysis by Loew [17] does not find sufficient evidence in favor of DTF on pain, improvement of grip strength and fonctional status. One randomized controlled trial with 40 patients with lateral epicondylalgia was included in the analysis and did not show statistically significant result in favor DTF. Many studies are excluded from analysis for insufficient methodological quality but no studies include a DTP technique in their protocol.

Our pilot study show a significant benefit of the use of the MyoDK for DTP in lateral epicondylalgia. We were able to show a significant reduction in pain using DTP at both 3 and 6 weeks follow ups. Moreover, only 2 patients were lost to follow-up and no patient asked or needed to be switched to another treatment modality, which make the use of the MyoDK for a standardized DTF protocol a very well tolerated and accepted treatment.

The treatment is safe because perpendicular application of pressure causes no shear stress on the different layers of tissue with therefore very low risk of lesion. Moreover this can also explain why this treatment modality is much more tolerated than DTF. After a few sessions pressure superior to 6 kg/100mm² could be applied.

Our study is the first to address the problem of pressure measurement during treatment in epicondylalgia. By defining and recording the pain threshold at the location of the epicondylalgia, at each visit, we were able to apply consistent pressure and show the patient his progress. The procedure has allowed great adherence of the patients with low rate lost to follow up. There hasn’t been any adverse effect reported although the treatment protocol was reaching pain thresholds at each study. To our knowledge the maximum amount of pressure that can be reached by applying pressure perpendicularly to a tendon hasn’t been study. However Kukulka has reached 10 kg (N/mm²) on Achille tendon [18]

Having a numeric value for the pressure applied allows for low inter and intra operator variability, which is fundamental for the evaluation of new techniques, and solves for a major shortcoming in the evaluation of any manual therapy.

High pressure are difficult to reach for the therapist because they put tremendous pressure on his/her hands, most notably the trapeziometacarpal joint and can result in trapeziometacarpal joint degenerative disease over the long term [19]. Moreover those high are rarely reached and most probably never sustained because of human biomecanic physiological limitation. The MyoDK device allows the application of high pressure on the treatment area using the physician’s body weight and eliminating pressure from the physician’s hand. This is of significant importance in the treatment of obese patients or athletes with high muscular density, and to avoid physician chronic hand pain.

Our pressure protocol is similar to DTF but is less painful because there are no transverse friction and is therefore closer to manual ischemic compression. The emergence of the myofascial trigger point concept as a potential generator of myosfascial pain in epicondylalgia was reviewed by Shmushkevich [20] and offers a insightful approach to the relevance of ischemic compression technique for the treatment of musculo-skeletal pain. Contrary to ischemic compression the device allows modulation of the pressure applied during the treatment, probably modulating ischemic pressures.

Perpendicular pressure or DTF has the ability to modify tissue intrinsic property by increasing tolerance to strech. At the microscopic level those techniques probably modifies collagen cross-linking [6]. At the difference of stretching manipulation (as in the glinding technique) direct pressure techniques probably have the potential to modify collagen hydratation and collagen unfolding [21,22].

Physical therapy literature offers one pilot study by McLean and al., [23], that aimed to physically evaluate the pressure required to produce analgesia during manual therapy. The manipulative treatment aimed to realize a lateral glide and was to be associated with voluntary movement of the patient. They found the best results were obtained with higher pressure applied. Similarly, each treatment in our study aimed to reach higher pressure and was a criterion for follow-up during the course of the treatment.

Kukulka and et al., [18] found that by doing perpendicular pressure on Achille tendon, H reflex was decreased in soleus muscle but there was not difference between 5 and 10 kg pressure [18].

Pain regulating mechanism i.e diffuse noxious inhibitory control by treating arm at different locations, are present but we believe there is poor if any neurological sustained effect [18,20,24].

In this study, the use of the MyoDK for DTF in the treatment of LE had favorable results as we were able to significantly improve patient pain using a reliable and reproducible protocol. In this study chronic patient can be considered their own control if we consider the length of symptoms. Our next steps in the evaluation of this new technique are to compare the MyoDK for DTP to other treatments modalities in a randomized-controlled trial and allow us to better define the indications for this intervention

The use of the MyoDK for DTF of chronic lateral epicondylalgia showed good tolerability with no side effect. Besides significant pain reduction at 3 and 6 weeks were observed. The use of MyoDK allows reproducible pressure application for standardization of treatment, while significantly reducing stress to the physician’s hand.