Background Tennis elbow is a tendinopathy affecting the upper extremity. Recent studies have shown high sensitivity for ultrasound (US) examination and high specificity for colour Doppler (CD) examination. There are no mid- or long-term follow-up investigations of the tendon structure and blood flow using these techniques.
Objective To use US and CD to study structure and blood flow in the extensor origin in patients with tennis elbow treated with intratendinous injections.
Design Follow-up study
Setting Sports Medicine Unit, Umeå University.
Patients 25 patients (28 elbows), mean age 46 years (range 27–66), treated with intratendinous injections due to chronic pain from tennis elbow.
Method US and CD examination of the extensor origin was carried out at inclusion and at follow-up two years after intratendinous injection treatment with polidocanol and/or a local anaesthetic.
Main outcome measurements US (structure) and CD (blood flow) findings.
Results All patients had structural tendon changes and high blood flow at inclusion when given the injection treatment. At the two-year follow-up, structural tendon changes were seen in 20/28 elbows and high blood flow was seen in 4/28 elbows. The majority of patients with a good clinical result after treatment had no visible blood flow (17/20), but the structural changes showed no relation to a good result (13/20 remaining changes).
Conclusions Doppler findings, but not structure, might be related to the clinical result after intratendinous injection treatment of tennis elbow.
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Chronic pain from the common extensor origin at the lateral epicondyle, also called tennis elbow, is a condition well known to be troublesome to treat.1 The aetiology and pathogenesis are unknown, but a relation between repetitive forceful gripping and the diagnose tennis elbow has been shown.2 The origin of the pain is not known, but the general opinion is that the extensor carpi radialis brevis muscle and its tendinous origin plays a central role.3,–,5 Histological findings in the extensor carpi radialis brevis origin are microrupture, granulation tissue and degenerative changes, but without signs of traditional inflammation.4,–,8 Therefore, it has been suggested that the term lateral epicondylitis should be avoided and replaced by lateral elbow tendinopathy.9 Different methods have been tried to treat the condition, for example, physiotherapy,10 different types of injections,11,–,15 non-steroidal anti-inflammatory drugs,16 different types of surgical treatments,17 orthotic devices18 and rest, but there is little scientific evidence for their effects. The target for most methods is the common extensor origin. Treatment with injection is commonly used, and different substances have been tried for injection treatment locally in the extensor origin, for example, corticosteroids, platelet-rich plasma, autologous blood, sclerosing substance.11 12 14 19 In a recent study we have compared the effect of intratendinous injections of a sclerosing substance (polidocanol) and a local anaesthetic substance (lidocaine and epinephrine).19 Good clinical results were demonstrated in both groups, and it is possible that the ultrasound (US)- and colour Doppler (CD)-guided injection itself was more important than the substance injected.19
Previous studies using US and CD or power Doppler (PD) examinations have shown structural tendon changes (tendon thickening, hypoechogeneity, diffuse heterogeneity and calcification), bone spurs and increased blood flow in the extensor origin. A possible relation between increased blood flow and pain has been suggested.20 21 In most studies using US and/or CD examinations, the inclusion criteria for the control group has been no previous history of elbow pain, why there is a lack of knowledge if the sonographic findings remain over time. A study of another tendinopathy (Achilles tendon) has shown a “more normal” tendon structure and no or few remaining “neovessels” in successfully treated tendons, at a two-year follow-up.22
The aims of this study were to use grey-scale US and CD to study the structure and blood flow in the extensor origin two years after intratendinous injection treatment of painful tennis elbow. The hypothesis was that the structure would be normalised and the blood flow would be normal in successfully treated elbows.
Material and methods
Twenty-five patients (13 women and 12 men, mean age 46 years, range 27–66) with a long duration of pain (mean 18 months, range 3–60) diagnosed as tennis elbow, in 28 elbows (22 unilateral, 3 bilateral), were included.
The diagnosis tennis of elbow was considered present if there was pain on palpation of the extensor origin, pain elicited from the area on resisted wrist extension, together with structural changes and high blood flow in the extensor origin. Patients with differential diagnoses such as cervico-brachialgia and radial nerve compression were excluded based on history and clinical findings. All patients were treated with US- and CD-guided intratendinous injection targeting the area with structural changes and high blood flow. The substances used were sclerosing polidocanol and/or local anaesthetic (lidocaine, epinephrine). Previous treatment included locally, but blind, corticosteroid injections in 19/28 elbows.
All tendons were examined with high resolution grey-scale US and CD, Acuson Sequoia 512, with 8–13 MHz frequency. The examinations were carried out in a sitting position, with the arm resting on a table, having 70–80 degrees of elbow flexion and pronated wrist. CD was used to locate high blood flow. The same experienced radiologist (LÖ) performed all US and CD examinations.
Outcome measures and follow-up
Primary outcome measures were structural tendon changes in the extensor origin (diffuse heterogeneity and hypoechogeneity) demonstrated during grey-scale US, and high blood flow (not present or several areas) demonstrated with CD. Bone spurs were also registered. All patients were followed up two years after the first US- and CD-guided injection.
Secondary outcome measures were elbow pain during grip activities in daily life (including work situations), maximum grip strength and pain during maximum grip strength. Using a 100-mm visual analogue scale (VAS) for pain, the patient recorded the amount of elbow pain when using the grip (where no pain is recorded as 0 and severe pain as 100). Maximum voluntary grip strength was evaluated by using a hydraulic hand dynamometer (FEI Irvington, NY, USA). Maximum grip strength was measured three times, and the highest value was used for the statistical analysis. During the dynamometer test, the arm was held in the horizontal plane, with the elbow straight, and the wrist in neutral position. Pain during the maximum grip test was recorded (using VAS).
At follow-up two years after treatment, the radiologist who performed the grey-scale ultrasound and colour Doppler examination was blinded to which elbow, one or both, that had been treated.
The investigation was approved by the Ethical Committee of the Medical Faculty, University of Umeå.
SPSS V.14.0 was used for statistical calculations. Differences over time were calculated with Wilcoxon Signed Ranks Test.
All patients had structural changes (diffuse heterogeneity and hypoechogeneity) and high blood flow demonstrated with grey-scale US and CD. In 7/28 elbows there were bone spurs at the lateral epicondyle.
Two-year follow-up after injection treatment
In 20/28 elbows there were remaining structural changes, and in 4/28 elbows there were remaining increased blood flow, in the extensor origin. Bone spurs were found in 20/28 elbows.
In 17/20 extensor origins with a good clinical result after treatment, there was no visible blood flow.
In 7/20 extensor origins with a good clinical result after treatment, there were no structural changes.
The patients had a significantly lower VAS (71 (SD 16) vs 25 (SD 31), p<0.000) during elbow loading activity, a significantly higher grip strength (39 (SD 18) kg vs 49 (SD 17) kg, p<0.000) and a significantly lower VAS during maximum grip (72 (SD 23) vs 16 (SD 28), p<0.000) after compared to before injection treatment.
What is already known on this topic
Pain in patients with tennis elbow is elicited from the extensor origin at the lateral epicondyle.
Ultrasound examination of the extensor origin in patients with tennis elbow shows structural tendon changes.
Colour Doppler examination of the extensor origin in patients with tennis elbow shows high blood flow.
What this study adds
In the majority of successfully treated patients there is no remaining high blood flow on colour Doppler examination two years after intratendinous injections for tennis elbow.
Structural changes seen on ultrasound examination are still seen in the majority of patients two years after successful treatment with intratendinous injections for painful tennis elbow.
The main findings in our study were that the majority of the patients with a good clinical result after intratendinous injection treatment had no remaining high blood flow, but remaining structural changes, in the extensor origin.
We used CD examinations to evaluate the blood flow. There is a difference between CD and PD, CD showing directions of the flow, PD being more sensitive to flows. There are some limitations using grey-scale ultrasonography and Doppler examinations. There is no reliable method to calculate the flow. US and CD/PD examinations are very much examiner dependent23; positioning and pressure on the probe will affect the findings. The examination also depends on the patient; if tension in the wrist extensors is high, due to muscle contraction or by palmar flexion of the wrist, the blood flow is affected (decreased). The experience of the person performing US examinations is also important; the examiner must be able to distinguish normal from abnormal findings. Consequently it is of high importance to use an experienced radiologist, and in our study a radiologist with 25 years of experience in sonographic examinations did all US and CD examinations.
We believe the area with increased blood flow seen on CD examination is where the pain is elicited in tennis elbow. In a recent study the high specificity of PD was presented.21 Sensory nerves are found together with small blood vessels and if they are activated, and the patients experience pain, they might cause increased blood flow.24 US-guided injections in this area seem to have good clinical results.19
In our study there were remaining structural changes in the extensor origin in 13/20 patients that were successfully treated with intratendinous injections. Interestingly, this is in contrast to the findings in patients with midportion Achilles tendinosis treated with injections outside the ventral side of the tendon, were a majority of the successfully treated patients were found to have a normal tendon structure at a two-year follow-up.22 It could be argued that the remaining changes in the patients with tennis elbow were caused by multiple injections traumatising the extensor origin or previous cortisone injections. However, when comparing the number of injections given to the patients that were successfully treated and had no remaining structural changes with the number of injections given to the patients that were successfully treated and had remaining structural changes, there were no differences. Looking at previous cortisone injections, this was not related to remaining structural changes. Altogether, it seems that there might be differences in the potential for remodelling of the structure between intratendinous and extratendinous injection treatment? Or is there a difference in the potential for remodelling in the free tendon compared to the origin (enthesis)?
An interesting finding was that bone spurs in the most proximal extensor origin were more frequently found at two-year follow-up. Before the injection treatment seven patients had bone spurs at the lateral epicondyle, compared with 20 patients two years after treatment. There seem to be a formation of bone spurs over time, so called “lateral epicondyle enthesophytes”. It is tempting to believe that this is a consequence of remodelling due to the increased stress from overload. Since some patients still experience pain, but not in the extent that they have positive clinical signs and need further treatment, maybe it is this remodelling process with formation of bone spurs at the lateral epicondyle that is the source of pain?
We elected to use VAS for pain during daily activity, maximum grip strength and VAS for pain during maximum gripping as the secondary outcome measures. VAS is known to be a reliable instrument to score differences in pain over time. Still, it has its restrictions since the scoring needs to be related to the same level of activity each time. Less pain often leads to an increased activity level that may induce more pain. This might be the reason why female patients have higher VAS, they have less grip strength and more often reach maximum grip strength during daily activity. This did not affect our statistical analysis since we calculated by paired samples. As secondary outcome measure we also used grip strength. Grip strength is considered the best objective outcome measure after treatment for tennis elbow.25 Measuring the pain experienced during maximum grip was an attempt to differ tennis elbow from other sources of lateral elbow pain. If pain was not elicited during the test, there might be other causes to lateral elbow pain during daily activity.
In conclusion, in the two-year perspective it seems that blood flow detected by CD, but not structure, might be related to the clinical result after intratendinous injection treatment of tennis elbow.
Funding This study has been funded by the Swedish Research Council for Sports.
Competing interests None.
Ethics approval This study was approved by the Ethical Committee of the Medical Faculty, University of Umeå, Umeå, Sweden.