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Orthopaedics · sports medicine · clinical evidence
How does PRP therapy work in orthopaedics?
PRP is being studied for joint degeneration, chronic tendon disorders and selected sports injuries. Its effects depend heavily on the diagnosis, tissue, preparation and treatment protocol.
- Knee osteoarthritis
- Tendons
- Plantar fascia
- Shoulder
- Muscle injuries
- PRP preparation
Autologous blood productPRP is prepared from the patient’s own venous blood.
No standard recipeCell content, volume, activation and administration vary.
Dependent on indicationThe evidence for knee osteoarthritis differs from the evidence for tendon or muscle injuries.
Focus on symptomsStudies mainly assess pain, function and return to activity.
In orthopaedics, PRP is mainly used for degenerative joint symptoms, chronic tendinopathies and selected sports injuries. The method uses a processed plasma fraction obtained from the patient’s own blood.
The scientific assessment differs by condition. Evidence is comparatively extensive for mild to moderate knee osteoarthritis. Results remain less consistent for Achilles tendon disorders, shoulder conditions and acute muscle injuries.
What is PRP?
PRP stands for platelet-rich plasma. It is obtained from the patient’s own venous blood. Centrifugation separates the blood components and produces a plasma fraction with an increased platelet content.
PRP is not stem-cell therapy. Depending on the preparation system, it contains plasma and platelets as well as varying amounts of leucocytes and residual erythrocytes.
Definition
PRP does not describe one identical formula used everywhere, but a group of autologous blood products with different compositions.
From whole blood to a plasma fraction
Blood collection, centrifugation and separation of the required fraction form the technical basis. Only then is the preparation introduced into the joint or affected soft tissue.
AutologousThe starting material comes from the person being treated.
Cell-dependentThe proportions of platelets, leucocytes and erythrocytes shape the preparation.
Protocol-dependentThe system, centrifugation, dose and administration influence the composition.
How is PRP expected to act in tissue?
Platelets participate in blood clotting and release a range of signalling molecules after activation. These are associated with inflammatory responses, cell communication, blood-vessel formation and tissue remodelling.
In osteoarthritis, research mainly examines whether PRP can influence pain and function by altering the joint environment.
In tendinopathies, the aim is to modulate the local response in overloaded and structurally altered tendon tissue.
For acute injuries, studies mainly examine the time required to return to sporting activity.
An improvement in pain does not automatically demonstrate anatomical reconstruction.
Biological plausibility and clinically noticeable benefit must be assessed separately.
The term “regenerative” can be misleadingPRP contains biological signalling molecules. This does not mean that lost joint cartilage reliably regrows or that a damaged tendon is fully reconstructed.
Why is not all PRP the same?
International experts recommend describing PRP more precisely by cell composition, activation, dose, volume, route of administration and number of injections. A universally valid ideal dose has not yet been established.
Platelet count
Leucocyte proportion
Neutrophils
Erythrocytes
Total volume
Injection volume
Activation
Route of administration
Number of sessions
Studies are only partly interchangeableTwo studies may both examine “PRP” while using biologically different preparations, injection volumes and aftercare protocols.
Which orthopaedic conditions are being studied with PRP?
Indication matrix: evidence cannot be transferred across conditions without qualification
Diagnosis-dependentJointKnee osteoarthritis
Outcome studied
Pain and joint function in mild to moderate osteoarthritis.
Assessment
Comparatively extensive data, but no uniform recommendation for every patient group.
TendonTennis elbow
Outcome studied
Pain and function compared with corticosteroid injections.
Assessment
Corticosteroids may perform better in the short term, while PRP is sometimes better in meta-analyses over the longer term.
FasciaPlantar fasciitis
Outcome studied
Pain, function and plantar fascia thickness.
Assessment
Possible medium-term benefits, but no consistently clinically relevant superiority.
TendonAchilles tendon
Outcome studied
VISA-A function score and sonographic tendon thickness.
Assessment
A meta-analysis found no significant advantage over control treatments.
ShoulderRotator cuff
Outcome studied
Tendinopathy, partial tear and adjunctive use after surgery.
Assessment
Some moderate benefits, but no robust evidence supporting routine use in every situation.
MuscleAcute injury
Outcome studied
Time to return to sport and reinjury rate.
Assessment
A possible reduction in return time; studies are heterogeneous and confidence in the conclusion remains limited.
What does research show for knee osteoarthritis?
Knee osteoarthritis is one of the most frequently studied orthopaedic indications. Outcomes mainly include pain, joint function and patient-reported limitations.
Mainly mild to moderate osteoarthritis
The European consensus considers PRP a possible non-operative injection option, mainly for Kellgren–Lawrence grades 1 to 3.
Possible option84 of 216 scenarios rated appropriate
The assessment depended, among other factors, on age, osteoarthritis grade, effusion and previous treatments.
Strong patient selectionStill an evolving field
The current guidance combines evidence-based recommendations with expert consensus and calls for more robust dose-dependent studies.
Individual clinical decisionMany reviews have relevant weaknesses
An assessment of 41 systematic reviews found none with high methodological quality. Their conclusions should therefore not be generalised uncritically.
Cautious interpretation
Pain improvement is not proof of cartilage restorationEven when pain and function improve, this does not establish reliable rebuilding of lost joint cartilage.
How should PRP be viewed for tendon and fascia disorders?
Tennis elbow
Meta-analyses often show a time-dependent pattern: corticosteroids may be more favourable in the short term, whereas PRP sometimes achieves better pain and function scores after six months.
Long-term comparisonHigh heterogeneity
Plantar fasciitis
PRP showed statistically favourable pain outcomes in several comparisons. Compared with shockwave therapy, however, the difference did not reach a clinically relevant size in every analysis.
Medium-term dataNot consistently superior
No confirmed additional benefit
A meta-analysis of 422 people with chronic midportion Achilles tendinopathy found no significant benefit for either function or maximum tendon thickness.
6 publicationsNo significant difference
Tendinopathy is not the same as a rupture
Before an injection, clinicians must determine whether the condition is chronic tendinopathy, a partial tear, a complete rupture or another cause of pain.
Clinical examinationImaging according to findings
What do studies show for shoulder and muscle injuries?
Shoulder and sports injury: read the outcomes separately
Mixed evidenceRotator cuffTendinopathy and partial tear
Result
A meta-analysis of ten randomised studies found statistically better but overall moderate outcomes than corticosteroids after six months.
Limit
The benefit was not clearly superior during the first weeks or at three months.
Surgical shoulder treatmentAdjunct during repair
Result
One review reported a tendency towards fewer retears and better function.
Limit
The differences were not significant, and a routine benefit was not established.
HamstringAcute muscle injury
Result
A meta-analysis of six randomised studies reported an earlier return to sport on average.
Limit
Heterogeneity was high, and the reinjury rate did not differ clearly.
“Faster return to sport” is not a guaranteeInjury severity, rehabilitation plan, load management and return-to-play criteria influence the course independently of the blood product used.
When might an effect be expected?
PRP does not act like a local anaesthetic. In studies, a possible clinical change is usually assessed after several weeks and again after three, six or twelve months.
A local reaction is possible
Temporary pain, tenderness or swelling may occur. This reaction proves neither success nor failure.
No uniform course
Symptoms change in some patients, while others experience no relevant effect.
Common study endpoint
Many comparative studies assess pain and function during this period. The relevant endpoint depends on the condition.
Limited transferability
Long-term data are not available for every indication. The duration and magnitude of possible effects cannot be stated across the board.
Which factors influence the outcome?
Treatment results do not depend on the PRP preparation alone. Diagnosis, severity, comorbidities, lifestyle, injection placement and rehabilitation can alter the outcome.
Diagnosis
Disease stage
Duration of symptoms
Age
Body weight
Smoking
Comorbidities
Previous treatments
PRP composition
Injection target
Rehabilitation
Load management
A precise diagnosis remains the starting pointPRP does not replace an orthopaedic examination, necessary imaging or a structured rehabilitation programme.
How is an orthopaedic PRP procedure carried out?
Medical history, examination and imaging where required establish the target structure and treatment alternatives.
Venous blood is collected in a dedicated system and centrifuged according to the manufacturer’s protocol.
The prepared fraction is injected into the joint or affected soft tissue, with imaging guidance where appropriate.
There is no universally valid injection volume or number of sessions. Volume, frequency and intervals depend on the indication, preparation and medical protocol.
What risks and side effects are possible?
Because the preparation is obtained from the patient’s own blood, classic allergic reactions to the main component are unlikely. “Autologous” does not mean risk-free.
Possible effects include temporary pain, swelling, tenderness, small bruises, bleeding, local irritation, infection and injury to adjacent structures.
In the presence of infection and certain haematological, immunological or oncological conditions, an individual medical assessment is required.
Sterile preparation, correct injection technique and appropriate patient selection remain independent safety factors.
A systematic analysis of 91 randomised studies involving 5,914 intra-articular knee injections documented no joint infection in the included studies. This does not establish general freedom from risk.
Technical context of PRP preparation
The tube system, anticoagulant, separation gel, relative centrifugal force, rotor radius, run time and further processing steps influence the resulting plasma fraction.
Technical module: components of a standardised workflow
The following information describes technical product characteristics. It is not a recommendation, efficacy claim or approval for a specific orthopaedic treatment.
Vi PRP-PRO
Sterile borosilicate-glass PRP tube with sodium citrate and thixotropic separation gel.
- Volume
- 10 ml
- Additives
- 0.8 ml sodium citrate · separation gel
- Reference setting
- 1,200 × g · 7 minutes
- Plasma yield
- Approx. 4–5 ml as a system-specific reference value
Hettich EBA 200 MD
Compact centrifuge with an integrated eight-place angle rotor for medical use.
- Rotor
- 8-place · fixed angle · E3694
- Capacity
- Maximum 8 × 15 ml
- Maximum
- 6,000 rpm · 3,461 × g
- Protocol
- The system and manufacturer instructions are authoritative
Frequently asked questions about PRP therapy in orthopaedics
Can PRP rebuild joint cartilage?
Reliable rebuilding of lost joint cartilage has not been demonstrated clinically. Studies mainly examine changes in pain and function.
For which orthopaedic condition is PRP best studied?
The largest body of evidence concerns knee osteoarthritis. Even there, assessment and suitability depend on osteoarthritis grade and other patient characteristics.
How many PRP injections are required?
There is no universally valid number of sessions. Depending on the indication, studies use either single injections or treatment series.
Does PRP work immediately?
A possible change is usually assessed only after several weeks. A short-term pain reaction after the injection is possible.
Is PRP suitable for every tendon disorder?
No. Evidence for tennis elbow, plantar fascia disorders and Achilles tendon disorders differs considerably. The exact diagnosis is decisive.
Is PRP treatment risk-free?
No. Despite the autologous starting material, local pain, swelling, bruising, infection and injury to adjacent structures are possible.
Summary of the evidence
PRP is an autologous blood product whose composition and use are not uniformly standardised. Studies mainly examine effects on pain, function and load tolerance.
For mild to moderate knee osteoarthritis, the evidence base is comparatively broad but methodologically heterogeneous. Individual meta-analyses suggest possible medium- or long-term benefits for tennis elbow and plantar fasciitis. A clear additional benefit has not yet been established for Achilles tendon disorders. Results for shoulder and muscle injuries remain dependent on the clinical setting.
PRP is therefore neither a universal solution nor inherently ineffective. Its professional assessment must reflect the diagnosis, disease stage, preparation, procedure and available alternatives.
Sources and further reading
- Consensus statements on PRP for musculoskeletal pathologies
- ESSKA-ORBIT consensus on blood-derived products for knee osteoarthritis
- ESSKA-ICRS consensus on PRP in different knee osteoarthritis scenarios
- AAPM&R guidance statement on PRP for knee osteoarthritis
- Methodological quality of systematic reviews on PRP in knee osteoarthritis
- PRP versus corticosteroids for lateral epicondylitis
- PRP versus other modalities for plantar fasciitis
- PRP versus shockwave therapy for plantar fasciitis
- PRP for chronic Achilles tendinopathy
- PRP versus corticosteroids for rotator cuff tendinopathy
- PRP as an adjunct in rotator cuff repair
- PRP and return to play after acute hamstring injury
- Joint infection data after intra-articular knee PRP injections
Medical notice:This article presents published study findings, professional assessments and technical information for educational purposes. It neither recommends nor advises against a specific treatment and does not replace medical examination, diagnosis or an individual treatment decision. Product references relate solely to technical aspects of PRP preparation.