New RCT: Does PRP Help After ACL Reconstruction?

Anterior cruciate ligament reconstruction is one of the most common serious knee operations, replacing a torn ligament with a tissue graft that then has to heal into the bone tunnels drilled to hold it and gradually remodel into something that behaves like a real ligament, a process called ligamentization. Recovery is not fast: it typically takes many months before a graft has matured enough to support a return to pivoting sports, and patients spend that time managing post-surgical pain and swelling while working through supervised rehabilitation. Anything that could speed graft healing or ease the recovery period without adding meaningful risk is of real interest to orthopaedic surgeons and physiotherapists.

Platelet-rich plasma, a concentrate of a patient's own platelets and growth factors prepared from their own blood, has been tested around ACL surgery for over a decade on the theory that delivering a concentrated dose of growth factors directly to the graft site might accelerate healing and reduce the early pain and swelling that follow surgery. The results across this body of research have been inconsistent, partly because, as a team from Longyan First Affiliated Hospital of Fujian Medical University in China pointed out when introducing their own 2026 trial, earlier studies used PRP in very different ways: some as a single application during surgery, others as repeated injections afterwards, with different PRP preparation methods and often without adequate blinding of outcome assessors. Their trial, published in Scientific Reports in July 2026, was designed specifically to address some of those weaknesses.

The researchers recruited 54 patients undergoing ACL reconstruction and randomly assigned them, using a computer-generated randomisation sequence with sealed opaque envelopes to conceal the allocation in advance, to either a PRP group (27 patients) or a control group (27 patients). Patients in the PRP group received an injection of PRP around the graft during the surgery itself, followed by three further injections at one, two and three weeks after the operation. Both groups followed an otherwise identical surgical technique and rehabilitation protocol, including early weight-bearing in a brace from the first week.

The trial's primary endpoint, the single outcome the study was specifically designed and powered to test, was the time taken to reach meaningful pain relief, defined as a visual analogue pain score of 3 or lower. Secondary endpoints, measured at 12 months, included the Lysholm knee score and the International Knee Documentation Committee (IKDC) score, both validated questionnaires used to assess knee function and symptoms, along with an MRI-based assessment of how well the graft had matured, based on signal intensity and fluid around the graft. Because the control group did not receive a sham saline injection at each time point, patients and the clinicians giving the injections knew which group a patient was in. To limit the impact of that, the people scoring the Lysholm and IKDC questionnaires, the radiologist reading the MRI scans, and the statistician analysing the results were all kept blinded to group assignment, and the primary pain endpoint was actually assessed before the first postoperative injection was even given, specifically so that unblinding after surgery could not influence that particular measurement.

On the trial's own chosen primary measure, PRP did not deliver a meaningful difference. The average time to reach a VAS pain score of 3 or lower was 2.56 days in the PRP group compared with 2.93 days in the control group, a difference of well under a day, and it did not reach statistical significance. In plain terms, patients getting PRP were not reliably feeling comfortable any sooner than patients who did not get it. This is an honest and important part of the study to highlight, because it directly contradicts a common assumption in some PRP marketing that the treatment meaningfully reduces early post-surgical pain, at least in the specific injection schedule and pain measure this trial used.

A negative primary result like this is not a reason to dismiss the rest of the study. Well-designed trials specify their primary endpoint in advance precisely so that a clear miss cannot be quietly reframed as a win by shifting attention to whichever secondary measure happened to look best. The researchers here were transparent that their primary endpoint was not met, which is the kind of honesty this evidence rating rewards rather than penalises.

Where the trial did find a difference was in the secondary outcomes measured at 12 months. Patients in the PRP group had significantly higher Lysholm scores (91.04 versus 85.74) and significantly higher IKDC scores (92.30 versus 83.59) than the control group, both validated measures of how well the knee is functioning day to day and during activity. The PRP group also showed reduced MRI signal intensity in the middle and lower portions of the graft, which the researchers interpreted as a sign of more advanced graft ligamentization, essentially the graft looking more like mature ligament tissue on imaging.

These are meaningful, patient-relevant outcomes. A knee that scores better on validated function questionnaires a year after surgery is one that is working better in daily life and sport, and a graft that shows more mature signal characteristics on MRI is one that may be more robust going forward, though imaging appearance is not a perfect stand-in for how a graft will actually perform under load over the following years. The researchers also noted this effect appeared to hold regardless of which graft diameter was used, suggesting the benefit was not simply an artefact of surgeons choosing thicker grafts for one group over the other.

The authors of the study were candid about the trial's weaknesses in their own limitations section, which is worth taking at face value rather than glossing over. Because the control group received no sham injections, patients and the clinicians administering the postoperative injections were not blinded, which opens the door to expectation effects influencing how patients rated their own function on the Lysholm and IKDC questionnaires, even though the people scoring those questionnaires did not know the group assignment. The sample size was also modest at 54 patients split into two groups of 27, and the group had an uneven male-to-female split, both of which limit how confidently the results generalise to a broader population. This was also a single-centre study conducted at one hospital in China, which raises the usual question of whether the same protocol, using the same PRP preparation method and surgical technique, would produce similar results elsewhere.

None of this means the functional and imaging findings are meaningless, but it does mean this should be read as one reasonably well-designed trial adding a data point to an inconsistent literature, not as a definitive answer. The fact that the primary, hardest-to-influence outcome (assessed before any unblinding could occur) showed no benefit, while the more subjective, patient-reported secondary outcomes did show a benefit, is exactly the pattern that calls for some caution about how much of the functional improvement reflects a genuine biological effect on graft healing versus expectation and reporting effects in an unblinded trial.

This trial lands in a research field that has struggled with the same core problem across many PRP applications: real biological plausibility and some positive signals, mixed in with substantial heterogeneity in how PRP is prepared, dosed and timed across different studies, making it hard to draw one confident, generalisable conclusion. The Longyan team's own review of prior ACL literature noted that earlier PRP-and-ACL studies varied widely in these same ways, which is part of why they designed a study with a single, clearly pre-specified primary endpoint rather than reporting on whichever measure looked most favourable after the fact.

A related, more rigorously blinded 2024 randomised trial testing PRP combined with bone marrow aspirate concentrate around ACL reconstruction also reported functional benefits, which is broadly consistent with the idea that biologic augmentation can measurably help ACL recovery in some trials. But that trial tested a different, combined intervention rather than PRP on its own, so it should be read as compatible supporting context rather than a direct replication of this specific finding. Readers should come away from this with a fair, two-sided picture: PRP after ACL reconstruction has not been shown to speed early pain relief in this trial's careful primary analysis, but there is a genuine, if not yet independently confirmed for PRP alone, signal that it may support better functional recovery and graft maturation over the first year.

PRP is available at orthopaedic clinics, sports medicine practices and specialist injection clinics across Ireland, including in Dublin, Cork, Galway and Limerick, and some surgeons already offer it as an optional adjunct around ACL reconstruction and other sports injuries. It is not covered by the public healthcare system, and most private health insurance plans in Ireland do not reimburse it, so patients considering it as an add-on to ACL surgery should expect to pay out of pocket. Typical pricing for PRP injections in Ireland runs around €300 to €600 per injection, and a protocol involving several injections around the time of surgery, similar in principle to the schedule used in this trial, would multiply that cost accordingly. Prices last checked September 2026 and vary by clinic and preparation method, so confirm current rates directly with your surgeon or clinic.

If you are considering PRP alongside ACL reconstruction, this trial gives you a genuinely useful, specific question to raise with your surgeon: what outcome are you expecting it to help with. Based on this evidence, it would be reasonable to discuss it as a potential aid to longer-term function and graft healing, but not as something likely to make the first days or weeks after surgery meaningfully less painful, since that is precisely the outcome this trial's primary analysis did not support.

This is a genuinely mixed result, and that is a more useful thing to publish than a tidy, one-directional headline would be. A carefully designed randomised trial found that PRP did not achieve its stated goal of speeding early pain relief after ACL reconstruction, a clear and honestly reported negative finding on the primary endpoint. At the same time, the same trial found significantly better function scores and MRI-assessed graft healing at 12 months in the PRP group, an encouraging secondary finding that fits a broader, still-incomplete pattern of evidence for PRP in orthopaedic and sports medicine applications.

The practical takeaway is to treat PRP around ACL reconstruction as an option with a plausible, partially evidenced functional benefit rather than either a proven recovery accelerant or something without merit. Given the trial's limitations, in particular the unblinded injections and modest single-centre sample, anyone considering it is best served by an honest conversation with their surgeon about which specific outcome they are hoping to influence, what it costs, and how confident the current evidence actually allows either of you to be.