2 The procedure
2.1.1 Tennis elbow (also known as lateral epicondylitis) is characterised by chronic degeneration at the origin of the extensor carpi radialis brevis muscle on the lateral epicondyle of the humerus. It is usually caused by injury or overuse. Symptoms include pain, weakness and stiffness of the outer elbow.
2.1.2 Conservative treatments include rest, application of ice, analgesic medication, non-steroidal anti-inflammatory drugs, orthotic devices, physiotherapy, eccentric training/stretching and corticosteroid injection.
2.2.1 Extracorporeal shockwave therapy is a non-invasive treatment in which a device is used to pass acoustic shockwaves through the skin to the affected area. Ultrasound guidance can be used to assist with positioning of the device.
2.2.2 Extracorporeal shockwave therapy may be applied in one or several sessions. Local anaesthesia may be used because high-energy ESWT can be painful. Different energies can be used and there is evidence that local anaesthesia may influence the outcome of ESWT.
2.2.3 The mechanism by which this therapy might have an effect on tendinopathy is unknown.
Sections 2.3 and 2.4 describe efficacy and safety outcomes from the published literature that the Committee considered as part of the evidence about this procedure. For more detailed information on the evidence, see the overview.
2.3.1 In a randomised controlled trial (RCT) comparing 272 patients treated by ESWT or sham ESWT, success was reported in 26% (32/124) and 25% (31/122) of patients, respectively, at 3-month follow-up (success defined as a Roles and Maudsley score of 1 or 2 out of 4 and no requirement for additional treatment). An RCT of 93 patients treated by ESWT or steroid injection reported treatment success (at least 50% improvement in Visual Analogue Scale [VAS] score) in 60% (29/48) and 84% (21/25) of patients, respectively, at 3-month follow-up (p < 0.05).
2.3.2 An RCT of 75 patients treated by ESWT or sham ESWT reported that at 3 months, 35% (14/40) and 37% (13/35) of patients, respectively, had at least a 50% improvement in VAS score for pain during the day (p < 0.01 in both treatment groups); and 30% (12/40) and 43% (15/35) of patients, respectively, had at least a 50% improvement in VAS score for pain at night (p value stated as 'non-significant' and p < 0.05, respectively).
2.3.3 The Specialist Advisers listed key efficacy outcomes as relief of symptoms and functional improvement.
2.4.1 Two RCTs of 272 and 114 patients reported pain in 11% (15/134) and 50% (28/56) of ESWT patients, and 4% (6/136) and 22% (13/58) of sham ESWT patients, respectively.
2.4.2 In the RCT of 272 patients, transient skin reddening occurred in 31% (42/134) of ESWT patients and 8% (11/136) of sham ESWT patients, and transient swelling occurred in 7% (9/134) and 6% (8/136) of patients, respectively.
2.4.3 The RCT of 114 patients treated by ESWT or sham ESWT reported a local reaction (not otherwise described) in 11% (6/56) and 9% (5/58) of patients, respectively. In this study 18% (10/56) of patients in the ESWT group experienced nausea compared with none in the sham ESWT group.
2.4.4 In the RCT of 75 patients, 2 patients in the ESWT group had worsened symptoms after 2 treatment sessions and withdrew from the study.
2.4.5 The Specialist Advisers listed adverse events as bruising, transient skin reddening and local skin damage. Theoretical adverse events include rupture of the common extensor tendon.
2.5.1 The Committee found interpretation of the data difficult because of the diversity of treatment protocols and comparators used, varying reported end points and inconsistencies in terms of the use of local anaesthesia and energy type. The results of studies conflicted and there was evidence of a substantial placebo response. Previous guidance on this procedure published in 2005 had found the evidence on efficacy inadequate, and new evidence has not been published to alter that view.
2.5.2 Tennis elbow is a common condition and many patients who have it are refractory to other treatments. If the procedure is efficacious in selected patients, it has the potential for a high impact. This makes provision of robust data particularly important.