Leukocyte-Poor Platelet-Rich Plasma Reduces Pain Symptoms in the Treatment of the Lateral Epicondylitis

Lateral epicondylar tendinopathy (LET), or tennis elbow, is a degenerative condition affecting the forearm's extensor tendons. It commonly leads to pain, reduced grip strength, and impaired function, particularly in individuals performing repetitive wrist and forearm movements. Standard treatments, including physiotherapy, braces, and anti-inflammatory medications, provide relief but do not always lead to full recovery. Platelet-rich plasma (PRP) has gained interest as a regenerative therapy with the potential to enhance tendon healing and improve clinical outcomes.

This randomized, double-blind, placebo-controlled trial aims to evaluate PRP's effectiveness in treating LET, comparing it to leukocyte-rich PRP (L-PRP) and saline (placebo). Additionally, it assesses the composition of PRP and its role in tendon regeneration.

The study will enroll 80 patients diagnosed with LET, meeting predefined clinical criteria. Participants will be randomized into three groups (PRP, L-PRP, saline) and receive two injections (day 0 and day 7). PRP will be prepared using a standardized protocol to ensure consistency.

Patients will undergo clinical evaluations (VAS, Mayo Elbow Score, SECEC Elbow Score), grip strength testing, and MRI scans at baseline and 24 weeks post-treatment. The PRP composition will be analyzed in a laboratory. Follow-ups will be conducted at 12, 24, and 54 weeks to monitor pain reduction, functional improvement, and tendon healing.

This study will provide critical insights into PRP's therapeutic potential, helping refine treatment approaches for LET and improve patient outcomes.

Detailed Description

Study Rationale

Lateral epicondylar tendinopathy (LET), commonly referred to as tennis elbow, is a chronic degenerative condition affecting the common extensor tendon (CET) at the lateral epicondyle of the humerus. It is commonly observed in individuals engaged in repetitive wrist and forearm movements, such as athletes, manual laborers, and office workers. The primary pathological mechanism involves microtears leading to pain, reduced grip strength, and impaired function.

Conservative treatments, including physiotherapy, nonsteroidal anti-inflammatory drugs (NSAIDs), corticosteroid injections, and bracing, often provide temporary symptom relief but do not facilitate tendon regeneration. Corticosteroid injections may offer short-term pain relief but have been associated with tendon degeneration and higher recurrence rates. Given the limitations of these treatments, platelet-rich plasma (PRP) has emerged as a promising biological therapy due to its high concentration of growth factors that promote tissue healing, angiogenesis, and anti-inflammatory effects.

However, the optimal formulation of PRP remains controversial. Some studies suggest that leukocyte-rich PRP (L-PRP) may enhance the inflammatory response and accelerate healing, while others indicate that leukocyte-poor PRP (LP-PRP) may have superior effects by reducing excessive inflammation. The cellular composition of PRP is not standardized across clinical studies, leading to variability in treatment outcomes. This study seeks to clarify the role of PRP in LET treatment, determine whether L-PRP offers superior benefits, and evaluate its effects on pain relief, functional recovery, and tendon healing over time.

Study Design and Methodology

This is a randomized, double-blind, placebo-controlled clinical trial designed to evaluate the efficacy of PRP and L-PRP, saline compared to saline injections in treating LET. The study will enroll 80 symptomatic patients diagnosed with LET based on clinical criteria. Patients will be randomly assigned to one of the three treatment groups:

PRP Group (n=20): Standard platelet-rich plasma injection

L-PRP Group (n=20): Leukocyte-rich platelet-rich plasma injection

Saline Group (Control) (n=20): Placebo (saline) injection

Both PRP and L-PRP will be prepared using a standardized, non-commercial protocol to ensure consistency in cellular composition. Blinding procedures will ensure that neither the patients nor the evaluating clinicians know which treatment is administered.

Patient Selection Criteria

Inclusion Criteria:

Age 18-65 years

Diagnosed with chronic lateral epicondylitis (duration \>6 months)

Positive clinical tests: pain on resisted wrist extension and decreased grip strength

Written informed consent

Exclusion Criteria:

Previous elbow surgery or PRP treatment

Corticosteroid injections within the past 3 months

Systemic inflammatory or autoimmune diseases

Pregnancy or breastfeeding

Neurological conditions affecting upper limb function

PIN syndrome

Treatment Protocol

Pre-Treatment Evaluation:

All patients will undergo:

Clinical assessment of pain and function

VAS and Oxford Elbow Score questionnaires

Grip strength testing using BTE

MRI imaging of the affected elbow (baseline)

Injection Procedure:

Blood Collection: 30 ml of venous blood will be drawn from each patient

Centrifugation: Blood will be centrifuged at 2054 g for 7 minutes to separate PRP fractions

PRP/L-PRP Preparation: The appropriate PRP fraction will be extracted (with or without leukocytes)

Injection: 2 ml of PRP or L-PRP will be injected into the CET, with 1 ml retained for laboratory analysis

Control Group: Patients will receive an equivalent saline injection following the same procedure

Post-Treatment Rehabilitation:

Guided physiotherapy program focusing on eccentric strengthening

Use of elbow braces during daily activities

Activity modification guidelines

Outcome Measures and Follow-Up

Primary Outcome:

Pain reduction measured by VAS score

Secondary Outcomes:

Functional improvement assessed using Oxford Elbow Score

Grip strength recovery using a digital dynamometer BTE Structural tendon healing assessed via MRI at baseline and 24 weeks post-treatment

Follow-Up Schedule:

Week 0: Baseline assessments and first injection

Week 1: Second injection

Week 12: First follow-up visit (VAS, Oxford Elbow Score, grip strength)

Week 24: Second follow-up visit (MRI assessment, VAS, Oxford Elbow Score, grip strength)

Week 54: Final follow-up visit (long-term clinical evaluation, VAS, Oxford Elbow Score, grip strength)

Laboratory Analysis

PRP samples will be analyzed for platelet concentration, leukocyte content, and growth factor levels

Comparative analysis between PRP and L-PRP to correlate biological composition with clinical outcomes

Expected Impact and Clinical Relevance

This study aims to establish a standardized PRP protocol for LET treatment and determine whether PRP offers superior benefits compared to conventional approaches. The results will provide:

High-quality evidence for clinicians regarding PRP effectiveness

Guidance on PRP formulation (leukocyte-rich vs. leukocyte-poor)

Objective MRI data to track structural healing of the common extensor tendon

Improved treatment strategies to enhance patient recovery and reduce recurrence rates

By correlating PRP composition with clinical and imaging outcomes, this trial will help refine biologic treatment strategies for chronic tendinopathies, ultimately improving evidence-based management of LET.

Eligibility Criteria:
Inclusion Criteria:

* first-time diagnosis of chronic lateral epicondylitis with a duration of at least 1 month, age of 18 years or more, and signed informed consent to participate in the study

Exclusion Criteria:

* pregnancy, any previous treatment for the condition (including injections around the elbow, rehabilitation, or use of orthoses), previous surgical treatment of the elbow, other painful elbow conditions, co-existing upper limb and/or neck pain, prior elbow trauma or arthritic changes, posterior interosseous nerve (PIN) neuropathy, and systemic disorders