Comparing Autologous Blood, Corticosteroid, and Their Combined Injection for Treating Lateral Epicondylitis: A Randomized Clinical Trial
Phase: NA
Conditions: Lateral Epicondylitis, Comparing Autologous Blood Corticosteroid and Their Combined Injection for Treating Lateral Epicondylitis
Sponsor: Istanbul Training and Research Hospital

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Comparing Autologous Blood, Corticosteroid, and Their Combined Injection for Treating Lateral 
Epicondylitis: A Randomized Clinical Trial 
Albert CAKAR1, MD                                  dralbertcakar@gmail.com ORCID: 0000-0002-1422-2208 
1. Istanbul Training and Research Hospital, Department of Orthopedics and Traumatology, 
Istanbul, Turkey 
Corresponding author: Dr. Albert CAKAR 
Address:  
E-mail:  
 
 
GSM: +90  
Compliance with the ethical standards  
• 
Conflict of interest: Authors have no conflict of interest to declare. 
• 
Funding: No funds have been received for this study.  
• 
Ethical approval: The Institutional Review Board approved the study protocol (2023/137) 
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Informed consent: Written informed consent was provided by the participants.  
• 
Acknowledgements: None 
• 
Data availability statement: Data are available from the authors upon reasonable request. 
• 
Authors’ contribution: Study conception and design: AC, Acquisition of data: AC, Analysis and 
interpretation of data: AC, Drafting of the manuscript: AC, Critical revision: AC, (Initials of authors’ 
names) 
 
 
 
 
 
 
 
 
 
 

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Comparing Autologous Blood, Corticosteroid, and Their Combined Injection for Treating Lateral 
Epicondylitis: A Randomized Clinical Trial 
Abstract 
Objective: This study aimed to compare the efficacy of autologous blood (AB) and corticosteroid (CS) 
injections, as well as their combination, in treating lateral epicondylitis (LE). 
Design:  Randomized controlled trial 
Methods: A total of 120 patients diagnosed with lateral epicondylitis were divided into three therapeutic 
injection groups. The AB group received a mixture of 1 ml of autologous venous blood and 2 ml of 2% 
prilocaine HCl (Priloc %2, Vem, Turkey). The CS group received a mixture of 1 ml of 40 mg 
methylprednisolone acetate (Prednol-L 40 mg, Mustafa Nevzat, Turkey) and 2 ml of 2% prilocaine HCl. 
The combined group received a mixture of 1 ml of autologous venous blood, 1 ml of 40 mg 
methylprednisolone acetate, and 1 ml of 2% prilocaine HCl. Follow-up assessments were conducted on 
days 15, 30, and 90. 
  Keywords: Lateral epicondylitis; Tennis elbow; autologous blood; corticosteroid 
Level of evidence: Randomized clinical trial, Level 1 evidence  
 
Abbreviations 
AB: Autologous blood, CS: Corticosteroid, LE: Lateral epicondylitis, PRTEE: Patient-rated tennis elbow 
evaluation, HGS: Hand Grip Strength 
1. Introduction 
Lateral epicondylitis (LE) is a common musculoskeletal disorder affecting the extensor tendons 
of the forearm, manifesting as pain on the lateral side of the elbow and functional limitation during daily 
activities. Despite its name suggesting inflammation, histopathological examinations of the tendon 
reveal non-inflammatory angiofibroblastic tendinosis, accompanied by neovascularization, disorganized 
collagen, and mucoid degeneration [1, 2]. Since tendon degeneration is the underlying pathology, an 
effective therapeutic approach should reverse the degeneration to regeneration, ensuring symptom 
relief without recurrence. 

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Although many treatments exist, a consensus on the optimal single treatment for LE remains 
elusive. Traditionally, injections have served as a preliminary measure before resorting to surgical 
interventions, especially in resistant cases. However, an increasing number of alternative injections have 
been described in recent literature [3]. Newer injection therapies, such as autologous blood (AB) 
injections and platelet-rich plasma (PRP), have gained prominence and found favor among orthopedic 
surgeons. Multiple studies have attested to the safety and efficacy of AB and PRP injections as treatment 
modalities [4-7]. However, corticosteroid (CS) injections continue to be among the most commonly 
employed treatments for LE. A significant drawback of CS injections is their high recurrence rate. 
Patients typically experience a swift recovery immediately after injection, which endures for about a 
month. Unfortunately, this transient relief—often referred to as the 'honeymoon period'—is short-lived, 
leading to a recurrence of symptoms. Such a response pattern is well-documented in existing studies 
[8]. Conversely, AB injection therapy tends to proffer a gradual yet consistent reduction in symptoms, 
boasting a recurrence rate markedly lower than that of CS. It is postulated that AB addresses the intrinsic 
degeneration of the tendon, with its restorative process inherently spanning a more extended period [9-
11]. 
We hypothesized that a combination of CS and AB injection might offer a superior treatment for 
LE. This combination may provide a faster resolution of symptoms due to the initial action of CS and 
provide a lower recurrence rate due to the regenerative action of AB. The purpose of this randomized 
clinical trial is to test three different types of injection for the treatment of LE: (1) AB, (2) CS, and (3) their 
combination (AB+CS). 
2. Materials and methods 
2.1. Patients and study design 
A randomized clinical trial was carried out on eligible patients with a diagnosis of LE presented 
to our outpatient clinic. The diagnosis of LE was made with typical symptoms and physical examination 
findings, including pain and tenderness localized to the origin of forearm extensors and discomfort on 
the provoked wrist and middle finger extension. Patients whose complaints persisted for more than 3 
months were evaluated for inclusion in the study. 
Patients with a history of recent trauma, congenital or neuromuscular disease or abnormality of 
the upper limb, previous upper limb surgery, and history of rheumatic disease, history of cervical disc 

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pathology or carpal tunnel syndrome, systemic corticosteroid treatment, any previous local injection 
treatment, and finally patients with a history of previous allergic reaction towards local anesthetics and 
corticosteroids were all excluded from the study. All patients were over 18 years of age. The local ethical 
committee approved the study protocol (Approval number: 2023/137), and all patients gave their 
informed consent prior to their inclusion in the study. This prospective study was carried out following 
the ethical standards laid down in the 1964 Declaration of Helsinki and its later amendments. 
2.2. Treatment groups and randomization  
After taking informed consent, patients were randomly allocated into three treatment groups (AB 
versus CS versus their combination) with sealed envelopes prepared by a computer-based random 
number generator. A total of 120 envelopes were divided into three equal groups, 40 patients in each 
group. Patients in the AB Group received 1 ml of autologous venous blood mixed with 2 ml of 2% 
prilocaine HCl, patients in the CS Group received 1 ml of 40 mg methylprednisolone acetate mixed with 
2 ml of 2% prilocaine HCl, and patients in the Combined Group (AB+CS) received 1 ml of autologous 
venous blood, 1 ml of 40 mg methylprednisolone acetate mixed with 1 ml of 2% prilocaine HCl. Each 
group received an equal amount of (3 ml) injected material. Venous blood was collected from the 
antecubital fossa of the ipsilateral extremity. The senior author performed all injections, and neither the 
physician nor the patient was blinded to the treatment modality. The injection was administered in 
aseptic conditions, and the needle was introduced over the maximal tenderness point; the content of 
the syringe was injected at once to prevent further bleeding. All patients were instructed to abstain from 
heavy work, and no additional therapy, including NSAIDs or physiotherapy, was prescribed. 
2.3. Follow-up and outcome measures 
Functional outcomes were assessed with the patient-rated tennis elbow evaluation 
questionnaire (PRTEE). This outcome score consisted of 15 items related to three subscales, namely 
pain (5 questions), specific activities (6 questions), and daily activities (4 questions). The total score 
ranges between 0-100 points, 0 points designates the best functional outcome, whereas 100 points 
designates the worst functional outcome [12, 13]. To interpret PRTEE results, a minimum clinically 
important difference (MCID) value previously described by Poltawiski et al. was used [14]. According to 
his study, a 37% decrease in PRTEE is considered a ‘complete recovery’ or clinically significant change. 
PRTEE was assessed before the injection (baseline values), on Day 15, Day 30, and Day 90, in the 

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same manner by the senior author. The same author performed follow-up and data collection. No 
patients received more than one injection in this clinical trial.  
Hand grip strength (HGS) was measured with a digital hand dynamometer before and after 
injection in all patients. The senior author performed the measurements according to the American 
Society of Hand Therapists guidelines [15]. Since HGS varies according to factors such as height, 
weight, age, and gender, each patient's hand grip strength was calculated as a percentage increase 
from baseline. 
2.4. Sample size calculation 
 
In our pursuit to determine the optimal sample size for our study on LE treatments utilizing 
PRTEE scores, we based our assumptions on several crucial parameters. We anticipated a 37% change 
in baseline PRTEE scores and considered a standard deviation (SD) of 10, drawing from previous 
studies. We adopted a conventional significance level (α) of 0.05 and aspired for a power of 0.90, 
applying the ANOVA testing methodology for three distinct treatment groups. Our computations 
indicated that to discern this 37% shift in PRTEE scores with the targeted power and significance level, 
a sample size of roughly 33 participants per group would be essential. Thus, given the three treatment 
groups in our research design, the aggregate sample size was estimated at 99 participants. However, 
taking into account a 20% dropout rate, the study included a total of 120 patients, with 40 patients in 
each group. 
2.5. Statistical analysis 
Continuous variables were stated as mean and standard deviation, and categorical variables as 
percentages and frequency distribution. The conformity of the data to normal distribution was tested 
using the Kolmogorov-Smirnov test. For the comparison of continuous variables between the three 
groups, ANOVA was used for the data that fit the normal distribution, and the independent sample 
Kruskal-Wallis test was used for the data that did not fit the normal distribution. Categorical variables 
were compared using a chi-square test. Freidman test was used to assess the repeated measurements 
of the same group. A p<0.05 was set as a statistically significant alpha error.