Lateral elbow epicondylopathy remains one of the most perplexing disorders of the musculoskeletal system. It was first described by Runge in 1873. The designation lateral epicondylitis is a misnomer since it has been proved that it is primarily a disorder related to degeneration in the tendon of common extensor origin (mostly extensor carpi radialis brevis) rather than inflammatory process as was thought to be earlier. Maffuli et al. recognised that tendinopathy is a clinical diagnosis while tendinitis or tendinosis terms should be reserved only after histopathological examination has been carried out. A cadaveric study by Bales et al. showed two zones of hypovascularity in the region of lateral epicondyle, one between the lateral epicondyle and the supracondylar ridge and the other on the deep surface of common extensor tendon 2–3 cms distal to lateral epicondyle. This is probably the area where the degenerative changes set in (probably the same way as the supraspinatus tendinitis arises in a hypovascular zone just proximal to tendon insertion). The term Tennis elbow is not too apt since this disorder is commoner in occupations which involve repetitive forearm rotational activities. It has been estimated that only 5-10% of cases occur in tennis players. In our series, 52% cases were manual workers most of them mechanics, 24% were homemakers mostly females and rest 24% were involved in sedentary life style with teachers constituting a substantial 8%.
The optimal treatment strategy for lateral elbow tendinopathy has baffled treating doctors for long. A large percentage of cases (70-80%) report resolution of their symptoms within a year with or without treatment. Conservative line of management is usually the first line of treatment and consists of activity modification, rest, RICE (Rest, Ice, compression, elevation) therapy and non steroidal anti-inflammatory drugs. Manipulation under anesthesia has been reported to yield good results. Local corticosteroid injection is one of the commonest treatment prescribed in cases where initial activity modification and NSAIDs don’t work. However, a randomised control trial conducted by Bisset et al. found out that corticosteroid although effective at short term yielded poorer results at long term follow up (1 year) than physiotherapy.
Several nonsurgical modalities of treatment are under investigation which upon preliminary research have reported to provide some relief in symptoms of tennis elbow. Plazcek et al. investigated the role of Botulinum A toxin injection and found out that it offered significant pain relief. They reported significant weakness in the extensor movement of third finger but none of the patients lost time from work due to this weakness. D’Vaz conducted a double blinded randomised controlled trial and concluded that pulsed low intensity ultrasound therapy offered no significant benefit over placebo.
Recent reports have emerged suggesting a beneficial role of growth factors delivered locally at the site of tendinopathy. This can be accomplished by injection of autologous blood or platelet concentrates. Mishra and colleagues conducted a study wherein they treated patients of lateral elbow tendinopathy of less than 6 weeks duration by local injection of platelet rich plasma. They reported a significant improvement in pain. Similarly Edwards et al. reported dramatic relief in symptoms in 28 patients of tennis elbow after injection of autologous blood. They postulated that autologous blood initiated an inflammatory reaction which allowed healing in otherwise degenerative process. Although this study didn’t involve any control group, the authors hypothesized that blood injection would provide additional benefits over an injection of either saline or steroid. This belief was based on their observations that blood injections provided relief to patients who had failed multiple steroid injection attempts despite similar injection techniques and volumes. A systematic review done by Vos et al. however found that autologous blood has limited application in the management of tendinopathy. This was concluded on the basis of three studies[21–23] which involved management of plantar fasciitis with injection of autologous blood. The desired results may have not been achieved since the mechanical and healing properties of weight bearing and non weight bearing tendons differ a lot.
In our study, comparison between the two groups showed that both pain values and stage of the disease were similar at 2 weeks of review but there was a significant difference in both values at 6 weeks of follow up. Statistical analysis concluded that autologous blood was better than local corticosteroid injection in short term follow up of tennis elbow patients. This result came in direct consistency with study of Edwards et al. who reported maximal pain relief 3 weeks after injection of autologous blood (clinically pain relief was better at 2 weeks in steroid group in our study). Kazemi et al. also reported in their trial, that the benefits afforded by autologous blood injection outweighed those by local corticosteroid injection.
The mechanism of action of both autologous blood and platelet rich plasma is attributed to degranulation of α granules of platelets releasing growth factors which play a role in tissue healing and regeneration. Platelet derived growth factor, transforming growth factor β, vascular derived endothelial growth factor, epithelial growth factor, hepatocyte growth factor and insulin like growth factor are some of the factors involved. Platelet rich plasma (PRP) varies in the relative concentration of platelets ranging from 2.5 to 5 times as compared to blood. PRP logically appears to be more effective than due to higher concentration of growth factors per unit volume and has been proved in one clinical trial to be better than autologous blood. However preparation of platelet concentrates requires specialised equipment which is both expensive and time consuming. Autologous blood has a far easier and prompt application than PRP.
The mechanism of action of steroid remains obscure. Balasubramaniam et al. theorized that the beneficial effects of steroid injection result from the bleeding caused by forcing fluid through tissue planes at high pressures. In a study by Wolf et al. corticosteroid, autologous blood and saline injection all afforded the same benefit in cases of tennis elbow. This indirectly points out that these reported outcomes may also be due to the placebo effect of injection itself or a reflection of concurrent resolution of a self-limited disease. One might be led to believe that the disparity in the efficacy of autologous blood and corticosteroid observed in some series is due to the relative difference in the quantity of growth factors delivered to the degenerated tendon. However this doesn’t explain the fact that maximal relief encountered by both modalities peaks at different times.
We acknowledge that the major limitation of our study is a shorter follow up. Long term follow up study is required to test the ability of blood injection to maintain its analgesic effect for a longer time. However at longer follow up the contribution of treatment to relief begins to dilute as the natural tendency of the disease to heal starts manifesting in the form of pain relief. Further studies are required to optimise the number and spacing of injections for obtaining desired results. Short duration of symptoms in our series might be perceived as a potential limitation but since the threshold for steroid injection in tennis elbow is low, many of the patients with a longer duration of symptoms had invariably been treated with a steroid injection elsewhere and thus couldn’t be included in the study. As a corollary, since we enrolled only those patients which were previously untreated, further studies are needed to detect any difference in efficacy of blood injection in cases earlier treated with other modalities. Further research can also be directed at elucidating the exact mechanism of action of blood and steroid, which can be known only by indirect methods in human subjects.