October.indd

The use of a mobile lithotripter in the treatment of tennis elbow and plantar fasciitis

A. Mehra T. Zaman A.I.R. Jenkin
Trauma and Orthopaedics, Royal Glamorgan Hospital, Llantrisant, South Wales, CF72 8XR
Correspondence to: A. Mehra, House No.17, Staff Residences, Weston General Hospital, Uphill Road South, Uphill, Weston Super Mare, BS23 4TQ, U.K. Email: amehra@talk21.com

Introduction

Keywords: Mobile lithotripter, tennis elbow, plantar fasciitis
Surg J R Coll Surg Edinb Irel., 1 October 2003, 290-292

Objective: To evaluate the use of the mobile lithotripter in the treatment of tennis elbow and plantar fasciitis. Method: A prospective single blind randomised trial was performed on 24 patients with tennis elbow and 23 patients with plantar fasciitis, with a mean duration of symptoms of 11 months. All patients had failed one or more method of treatment - conservative, topical non-steriodal anti-inflammatory drugs (NSAID), steroid injection and/or surgery. The patients were divided into treatment and placebo groups. The placebo group received treatment with a clasp on the elbow/heel to stop penetration of shock waves. A baseline pain score was obtained using the Million Visual Analogue scale (0-10). The affected area was infiltrated with 3-5mls of 1% lignocaine. The treatment consisted of 2000 shock waves at 2.5 bars of air pressure with a frequency of 8-10Hz. A total of three treatments were given at an interval of two weeks, each lasting for three to four minutes. Results: In the treatment groups, a final pain score at six months post treatment showed significant improvement (three or more points) in 78% of patients with tennis elbow and 93% of patients with plantar fasciitis. In the placebo groups, significant improvement was seen in one patient (9%) with tennis elbow. The other patients in the placebo groups did not show significant improvement. This was statistically significant (chi square test) for both conditions. Conclusion: The mobile lithotripter is an effective way of treating tennis elbow and plantar fasciitis but warrants further larger studies

INTRODUCTION
Lithotripsy has been used in the treatment of renal stones for several decades. Soft tissues penetrated by shock waves show changes similar to those surrounding a fresh fracture, such as increased vascularity. This led to the application of this technology in the treatment of fracture non-unions.¹ The use has been widened to include treatment of enthesopathies. To date, the use and application has been restricted by the cost and limited availability of the fixed lithotripters. Low energy extra-corporeal shock waves have been used in the treatment of tennis elbow and plantar fasciitis in Europe with promising results.^2-6 We acquired on loan an EMS Swiss Dolorclast Mobile Lithotripter, to set up our prospective single blind randomised trial.

METHOD AND MATERIAL
Forty-seven patients (31 males and 16 females), with a mean duration of symptoms of 11 months, agreed to enter the study which was approved by the local ethics research committee. All patients had failed one or more methods of treatment - conservative, topical NSAIDs, steroid injection and/or surgery. A written consent was taken from all patients. Twenty-four of these patients had tennis elbow and 23 had plantar fasciitis. The patients were recruited from general practice, rheumatology clinics, orthopaedic units and from the accident and emergency department. They were randomised using 100 slips, letter ‘T’ for treatment on half and letter ‘P’ for placebo on the rest. Patients were asked to pick up a slip giving them equal chance to enter either group. The slip was then replaced in the box. Using this method, 13 patients with tennis elbow and 13 with plantar fasciitis were included in the treatment group and 11 patients with tennis elbow and 10 with plantar fasciitis were included in the placebo group.

There was no significant difference between the groups of patients with either tennis elbow or plantar fasciitis in terms of age, gender, duration of symptoms and previous treatment. Before the start of treatment a baseline pain score was obtained using the Million Visual Analogue Scale (0-10).⁷

All patients received 3-5mls of 1% lignocaine at the site of maximum tenderness followed by treatment with the mobile lithotripter on three occasions at two weekly intervals. Each treatment lasted three to four minutes; 2000 shock waves at an air pressure of 2.5 bars and frequency of 8-10Hz were given at each sitting. The patients in the placebo group received treatment with the clasp on the elbow/heel. They were not aware of the fact that they were not receiving treatment as the shock waves were intercepted by the clasp. The patients were reviewed in clinic at three and six months after the final treatment.

The treatment was given using the Electro Medical Systems (EMS) Swiss DolorClast System which consists of a control unit and a hand piece with two applicators of 15mm and 6mm diameters, for tennis elbow and plantar fasciitis, respectively. The desired number of shock waves, the operating frequency and the application pressure can be easily adjusted before or during treatment. The modular design allows the hand piece to be cleaned easily after treatment. A pressurised air source provided by a compressor is required to operate the Swiss DolorClast. Elaborate focussing is not necessary. A projectile in the hand piece propelled at high speed by a precision controlled pressurised air pulse hits the fixed applicator in the hand piece producing shock waves. These shock waves are emitted from the tip of the applicator and disperse radially in the body. Studies have demonstrated that the therapeutic effective penetration depth of these shock waves in humans is up to 35mm. These shock waves are transmitted into the pathologically changed regions over a wide area through the freely movable hand piece. Contact gel is used to minimise transmission loss.

Method of evaluation: A Visual Analogue Scale pain assessment was repeated to determine the response at three and six months after final treatment. An improvement in score by three points was considered to be significant. The statistical significance was calculated using the Chi Square Test by a medical statistician.

RESULTS
Tennis elbow: In the treatment group, the mean pain score of the 13 patients reduced from 6.6 to 3.0 at the six months follow-up. Ten patients (78%) showed significant improvement of three or more points, one patient reported no benefit and two patients complained of increased pain. In the placebo group (11 patients) the mean pain score dropped from 6.6 to 6.2. Only one patient showed significant improvement and 10 patients reported no change. The difference between treatment and placebo group was statistically significant.

Plantar Fasciitis: In the treatment group, the mean pain score of the 13 patients reduced from 5.9 to 1.9 at six months follow-up. Twelve patients (93%) showed significant improvement and one patient remained unchanged. No significant benefit was reported in the 10 patients in the placebo group. The mean pain score in this group dropped from 7.0 to 6.6. The difference between treatment and placebo group was statistically significant.

DISCUSSION
Tennis elbow and plantar fasciitis are disabling conditions that can interfere with many activities of daily living. The diagnosis of these conditions may be simple but the treatment is not always straightforward. Conservative treatment, steroid injection and surgery are some of the treatments used for these conditions.^8-14 Most patients in our study treated with the mobile lithotripter showed significant improvement after three treatments and the beneficial effects persisted at six months follow-up. Only one patient in the placebo group of patients with tennis elbow showed significant improvement.

Different hypotheses have been put forward explaining the mechanism of action of the mobile lithotripter. These include destruction of the cell membrane by shock waves resulting in failure of the pain receptors to produce signals, change of the chronic to acute inflammation which activates the body’s immune system and finally hyperstimulation analgesia. None of these have definitive evidence supporting them, but a synergistic effect involving all these mechanisms may be responsible.

During treatment eight patients complained of increased pain and four reported localised redness. At six months follow-up increased pain persisted in two patients. The side effects had settled completely in the others. Other side effects such as haematoma formation, migraine, syncope, hyperventilation and hypertension reported in previous studies were not seen.^15,16

Clotting disorders and pregnancy are two of the contra-indications for use of this form of treatment.¹⁶

CONCLUSION
The mobile lithotripter is an effective form of treatment for tennis elbow and plantar fasciitis. Although the results from this prospective randomised study are significant, the numbers are small. Larger studies, including the comparative effects of other forms of treatment, would be useful to determine the place of the lithotripter in the treatment of tennis elbow and plantar fasciitis.

ACKNOWLEDGEMENTS
Many thanks to Professor Moseley for his help with the statistics and to Electro Medical Systems for lending us the mobile lithotripter.

REFERENCES
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