Orthobiologics in Sports Medicine

Courtesy: Dr Anthony Luke, UCSF San FRancisco

Introduction

• PRP is one of the most commonly used orthobiologic treatments in orthopaedics and sports medicine.
• Orthobiologics include biological substances used to enhance tissue healing, such as:
  • PRP
  • Bone marrow aspirate concentrate
  • Mesenchymal stem cells.
• Among these, PRP is the most widely used in routine clinical practice due to relative simplicity and safety.

Platelets and Their Biological Role

• Platelets are small blood components essential for hemostasis and tissue repair.
• Approximately 250 million platelets are present in each milliliter of blood.
• Platelets contain growth factors and cytokines stored in intracellular granules.
• These growth factors have multiple biological effects, including:
  • Regulation of inflammation
  • Promotion of angiogenesis
  • Recruitment of reparative cells
  • Stimulation of extracellular matrix production.

Platelets influence several systems in the body and are not limited to blood clotting alone.

History of PRP

Early Scientific Understanding

• Platelets and their biological effects have been studied since the 1800s.

Discovery of Growth Factors

• Around the 1940s, researchers identified growth factors and cytokines involved in healing.

Early Clinical Use

• During the 1980s, platelet-based therapies were used for:
  • Wound healing
  • Tissue regeneration.

Use in Maxillofacial Surgery

• Oral and maxillofacial surgeons used PRP for mandibular fracture healing and bone regeneration.

Introduction into Orthopaedics

• PRP began to gain popularity in orthopaedics in the early 2000s, especially for:
  • Tendon injuries
  • Sports injuries.

Popularization in Sports Medicine

PRP gained public attention when used by elite athletes such as:

• Kobe Bryant – received PRP treatment for knee problems.
• Rafael Nadal – treated with PRP for chronic knee injuries.

PRP is also widely used in:

• Cosmetic medicine
• Hair restoration therapy
• Dermatology.

Definition of PRP

Platelet-rich plasma is defined as:

• Autologous plasma containing a higher concentration of platelets than baseline blood levels.

Earlier definitions required:

• ?3–5 times baseline platelet concentration

Recent definitions are broader and describe PRP as:

• Any plasma with platelet concentration above baseline levels.

Preparation of PRP

PRP is produced from autologous blood using centrifugation.

Basic Steps

1. Blood collection
   • Blood is drawn from a peripheral vein.
2. Centrifugation
   • Blood is spun in a centrifuge to separate components.
3. Separation of layers
   After centrifugation three layers are formed:
   • Bottom layer – Red blood cells
   • Middle layer – Buffy coat (white blood cells)
   • Top layer – Platelet-rich plasma
4. Collection of PRP
   • The platelet-rich portion is collected for injection.

Centrifugation Methods

Two main techniques are used:

• Single-spin method
• Double-spin method

Different commercial systems produce different platelet concentrations and growth factor levels.

Growth Factors in PRP

Platelets release multiple growth factors involved in tissue healing.

Important growth factors include:

• Platelet-derived growth factor (PDGF)
• Transforming growth factor-? (TGF-?)
• Vascular endothelial growth factor (VEGF)
• Insulin-like growth factor (IGF)
• Epidermal growth factor (EGF)

Functions include:

• Angiogenesis
• Cell proliferation
• Collagen synthesis
• Modulation of inflammation.

Variability in PRP Preparations

PRP preparations vary due to several factors:

• Different centrifugation techniques
• Different commercial kits
• Variable platelet concentrations
• Presence or absence of leukocytes
• Individual patient platelet counts.

Because of this variability, study results are difficult to compare.

Leukocyte-Rich vs Leukocyte-Poor PRP

PRP preparations are classified as:

Leukocyte-Rich PRP

• Contains white blood cells
• May increase inflammatory response.

Leukocyte-Poor PRP

• Reduced leukocyte content
• Preferred for intra-articular injections such as osteoarthritis.

Current evidence generally favors leukocyte-poor PRP for most orthopaedic indications.

Activation of PRP

PRP may be activated to release growth factors.

Activation methods include:

• Calcium chloride
• Thrombin
• Mechanical activation during injection.

However, many clinicians rely on natural activation within tissues after injection.

Orthopaedic Indications for PRP

Common indications include:

Tendon Disorders

• Lateral epicondylitis (tennis elbow)
• Achilles tendinopathy
• Patellar tendinopathy
• Rotator cuff tendinopathy.

Muscle Injuries

• Hamstring injuries
• Muscle strains.

Ligament Injuries

• Partial ligament tears
• Adjunct in ligament reconstruction.

Joint Disorders

• Knee osteoarthritis
• Early cartilage degeneration.

PRP in Knee Osteoarthritis

Evidence suggests PRP may provide:

• Better symptom relief than corticosteroid injections
• Slightly better outcomes compared with hyaluronic acid injections.

Typical duration of symptom relief:

• Steroids: 6–12 weeks
• Hyaluronic acid: 6–8 months
• PRP: up to 12 months in some patients

Number of PRP Injections

Protocols vary widely.

Common approaches:

• Single injection
• Series of 2–3 injections spaced 2–6 weeks apart

Some studies suggest multiple injections may provide better outcomes, but evidence is still evolving.

Procedure Considerations

Local Anesthesia

• Local anesthetics are often avoided as they may reduce platelet activity.

Image Guidance

• Ultrasound guidance improves accuracy of injection, especially for:
  • Tendons
  • Deep joints
  • Small structures.

Post-Injection Protocol

Evidence is limited, but common recommendations include:

Medications

• Avoid NSAIDs for about 1 week before and after injection.
• Paracetamol (acetaminophen) may be used for pain.

Activity

• Relative rest for several days
• Gradual return to activity.

Tendon Treatments

• May require:
  • Immobilization
  • Bracing
  • Activity modification.

Advantages of PRP

• Autologous (derived from patient’s own blood)
• Minimal risk of allergic reaction
• Very low infection risk
• No risk of disease transmission
• Can stimulate biological healing responses.

Limitations and Controversies

• Lack of standardized preparation techniques
• Variable platelet concentrations
• Inconsistent clinical study results
• Limited high-quality randomized controlled trials for some indications.

Future Research Directions

Current research focuses on:

• Identifying specific growth factors responsible for clinical benefits
• Determining optimal platelet concentration
• Standardizing preparation techniques
• Exploring advanced orthobiologics such as:
  • Bone marrow aspirate concentrate
  • Stem cell therapies