Why is PRP Important for Hip Osteoarthritis (OA)?
OA most frequently affects the knee and, after the knee, the hip is most often affected by OA. Aging and obesity are becoming more common, and both of these factors are contributing to an increased incidence of hip OA. OA significantly impacts quality of life and places a heavy financial burden on society. There are several non-surgical treatments for OA such as exercise, physical therapy, weight loss, pain-relieving drugs, and corticosteroid injections. While these may be effective in short-term pain relief, they may not alter the course of the disease. In fact, corticosteroid injections are known to destroy cartilage (Siengde, 2015).
Hyaluronic acid (HA) injections are effective in providing lubrication for the joint and reducing pain and inflammation with minimal side effects. Despite positive studies, clinical outcomes with HA have not been as good as expected. Since 2013, the American Academy of Orthopedic Surgeons (AAOS) has not recommended HA injections for symptomatic OA.
Most of the treatments mentioned above have not been effective in preventing OA progression nor in regenerating cartilage tissue. In recent years, biologics, such as PRP, have gained popularity because they have shown good results in knee OA.
What is PRP?
PRP is a treatment prepared from the patient’s own blood. The blood sample is centrifuged to result in a concentrated platelet layer that contains two to five times the number of platelets as normal serum. The PRP concentrate is rich in growth factors that have the potential to stimulate cartilage regeneration, growth of new vasculature, and cartilage matrix regeneration, while reducing destructive effects of catabolic cytokines.
The Study
This randomized study was conducted to assess the effect of ultrasound (US) guided intra-articular PRP injection on pain reduction and improved function in patients with hip OA. It also sought to compare the efficacy of PRP versus HA and to explore the combined effect of PRP plus HA on hip OA. One hundred and five persons with mild to moderate hip OA were included in the study and were divided into three treatment groups. There was no control group. All groups received two injections that were administered two weeks apart. The first group received 5 mL of PRP, the second group received 50 mg of high molecular weight HA in 2.5 mL, and the third group received 5 mL of PRP plus 2.5 mL of HA. A two-spin technique was used to prepare the PRP. Injections were administered under ultrasound guidance. Following the procedure, patients were instructed to rest for 24 to 48 hours and to take Tylenol, or Tylenol with codeine as needed, for pain control. Low to medium intensity isometric and stretching exercises were recommended for every patient. Patients were evaluated at baseline, two months, and six months.
The Results
Seventeen of the 105 patients reported warmth, stiffness, and heaviness regardless of group assignment. There was no meaningful difference in satisfaction between groups; overall, 59% of patients were satisfied with outcomes. The greatest dissatisfaction was observed in the two groups that received HA. All three interventions led to significant improvement in pain, stiffness, and function at two- and six-months post injection. Improvements were greatest (30%) in both the PRP and the PRP plus HA groups (groups 1 and 3). The effects of the two PRP groups lasted longer (6 months) than the effects of the HA-only group. There were no significant differences between these two groups. The authors state that adding HA to the PRP added no significant benefit.
The findings of this study are consistent with the literature that states that long-term (6 months) PRP demonstrates the best effect on pain reduction. Pain reduction and outcome improvement of PRP injection in hip OA continue 12 months after injection; however, these effects are more evident in the first 4–6 months. Younger patients with milder hip OA benefit more from PRP injections than older people with severe disease because it is thought that a lower percentage of viable cells exists, reducing the response to growth factors.
Summary
PRP is a safe and effective biologic agent for the treatment of hip OA. Best outcomes are seen in younger patients with less severe OA. There is no benefit to adding HA to the PRP preparation. Best PRP outcomes are seen at four to six months but improvements can be seen up to six months or one year.
References
Nouri, F., Babaee, M., Peydayesh, P. et al. (2022). Comparison between the effects of ultrasound-guided intra-articular injections of platelet-rich plasma (PRP), high molecular weight hyaluronic acid, and their combination in hip osteoarthritis: A randomized clinical trial. BMC Musculoskelet Disorder 23, 856. https://doi.org/10.1186/s12891-022-05787-8.
Siengdee, P., Radeerom, T., Kuanoon, S., et al. (2015). Effects of corticosteroids and their combinations with hyaluronanon on the biochemical properties of porcine cartilage explants. BMC Veterinary Research, 11, 298. https://doi.org/10.1186/s12917-015-0611-6
