The use of autologous platelet concentrate—platelet-rich plasma, or PRP—in a common type of anterior cruciate ligament (ACL) reconstruction surgery yielded no detectable clinical or functional benefit, although it may have led to better maturation and ligamentation, in a clinical study conducted by David Figueroa, MD, and colleagues.
The applicability of PRP in ACL reconstruction has been controversial. Dr. Figueroa, who presented results of his study at the AAOS 2010 Annual Meeting, noted that orthopaedists tend to believe that the use of PRP will improve mechanical properties during the remodeling phase, as well as the rate of incorporation and maturation. However, the literature is equivocal on this point, and more clinical studies with greater levels of evidence are needed to determine the mechanism of action on tissues when PRP is used in ACL reconstruction.
The investigators had hypothesized that applying PRP in the bone tunnels as well as on the hamstring graft at the time of final fixation would lead to “improved clinical, functional, isokinetic, and arthrometric results, and a rapid integration within the bone tunnel and an enhanced ligamentation process.”
Prospective, randomized study
The prospective, randomized, single-blinded study involved 50 patients who had similar characteristics and underwent the same arthroscopic reconstruction procedure with a semitendinosus-gracilis graft. Patients were randomized to receive reconstruction with a concomitant application of PRP (30) or to simply have the reconstruction procedure (20). Of the 10 mL of PRP prepared from 55 mL of each patient’s blood, 3 mL was applied in both the tibial and the femoral tunnels, and the remaining 4 mL was applied in the intra-articular portion of the graft.
All the procedures in the study were performed by two experienced sports medicine surgeons at a hospital in Santiago, Chile. Both groups of patients underwent the same accelerated rehabilitation protocol. At an average 6-month follow-up, the following assessments were made:
- Lysholm and subjective International Knee Documentation Committee pre- and postoperative scores were registered.
- Muscular function was evaluated with an isokinetic test during concentric muscle contraction at 60 percent, measuring flexor and extensor strength deficit and agonist/antagonist muscle balance.
- Arthrometric results were evaluated with KT-1000 testing.
Also at 6 months, magnetic resonance imaging was used to visualize the results, using signal intensity seen on the grafts in T2 sequences in sagittal sections and the presence of synovial fluid in the bone tunnels as detected by T2 potentiated sequences. If higher signal intensity between the graft and the bone tunnel was observed, the area was classified as positive for synovial fluid in the tunnel.
A five-point scoring system (Table 1) was devised to rate integration based on whether the graft signal was hyper-, iso-, or hypointense and on the presence or absence of synovial fluid in the graft-tunnel interface. Good integration was found in 97.4 percent of the PRP reconstructions and in 94.8 percent of the control reconstructions (p = 0.784). However, the PRP group had a higher rate of positives for synovial fluid than the control knees (13.2 percent versus 5.3 percent; p = 0.72). According to the authors, the literature has hinted that a positive finding indicates poor integration of the graft to the bone.
No significant differences
In the grading for functional knee postoperative scores, Dr. Figueroa said his team did not find significant differences between the two groups in terms of flexion strength deficit and muscular balance at 6-month follow-up (Table 2). They did note greater extension deficit in the PRP knees (p = 0.053) but could not identify the variables accounting for this finding.
Although this is the first study to examine these parameters in the same series of cases at 6-month follow-up, among the study weaknesses acknowledged by the authors is the fact that analysis was done with only one section at one given time. Further follow-up of this patient series is needed to determine whether the observed differences would become statistically significant over time.
Coauthors of “Effects of Platelet Rich Plasma in Hamstring Anterior Cruciate Ligament Reconstruction” are Patricio Meleán, MD; Rafael Calvo, MD; and Alex Vaisman, MD.
The authors reported no conflicts.
Terry Stanton is senior science writer for AAOS Now. He can be reached at email@example.com
- Applying autologous platelet concentrate in the bone tunnel as well as on the hamstring graft for ACL reconstruction does not appear to have clinical or functional benefits.