Platelet-Rich Plasma (PRP) therapy in the knee is a regenerative treatment that uses a concentration of your own platelets to stimulate the healing of damaged tissue. This process involves drawing blood, isolating the platelets and their growth factors, and then injecting the resulting plasma into the knee joint. The goal is to initiate the body’s natural repair process and help alleviate pain from conditions like osteoarthritis or tendon injuries. Following the correct aftercare protocol is important for ensuring the success of the procedure, as the initial days and weeks govern how effectively the growth factors can act.
Managing the First Few Days
The first 48 to 72 hours after a knee PRP injection are the most important. You should plan for a period of limited weight-bearing and rest immediately following the procedure to allow the injected plasma to settle in the joint space. While complete immobilization is not advised, you should restrict your activity to essential movements around the house. Some patients may be advised to use crutches or a cane to reduce pressure on the knee during this initial phase, depending on the injury treated.
It is normal to experience a temporary increase in pain, soreness, or mild swelling at the injection site. This initial inflammation typically subsides within the first few days and is a required part of the healing cascade. Managing this discomfort without interfering with the biological process requires specific care regarding medication choice.
You must strictly avoid non-steroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen, naproxen, and aspirin for a minimum of two weeks post-injection. NSAIDs inhibit the cyclooxygenase (COX) enzyme, which is necessary for platelet activation and the release of growth factors. Using these medications can counteract the therapeutic effect of the PRP treatment.
For pain management, the accepted alternative is acetaminophen, which does not interfere with the platelet function. Applying ice to the knee can also help manage swelling and discomfort, but some protocols suggest avoiding ice for the first 72 hours to allow the initial inflammatory phase to proceed naturally. If you do use ice, apply it for 15 to 20 minutes at a time, followed by a break, to avoid skin injury.
Reintroducing Movement and Activity
The focus shifts to carefully and gradually reintroducing movement to the knee to promote circulation and prevent stiffness. Gentle range-of-motion exercises, as directed by your provider, can usually begin after the first few days post-injection. This controlled movement is important because it helps lubricate the joint and encourages the newly stimulated tissues to adapt.
While light walking is generally encouraged to stimulate blood flow, you must avoid any high-impact activities such as running, jumping, or heavy lifting for the first two to four weeks. Excessive stress can disrupt the delicate healing environment created by the plasma. Most patients are cleared to begin a formal physical therapy program around one to two weeks after the injection.
Physical therapy focuses on strengthening the muscles surrounding the knee and restoring joint stability and flexibility. Patients should consider low-impact cardio like a stationary bicycle or swimming, once the injection site is fully healed, during the three- to six-week period. The return to more strenuous activities, including weightlifting or sports, is typically guided by your physical therapist and provider after approximately six weeks.
The healing process following PRP is not immediate, with noticeable improvements often becoming apparent between four and eight weeks post-injection. Peak benefits sometimes take three to six months to fully realize. It is important to listen to your body and use discomfort as a signal to reduce activity, as overexertion can cause setbacks. Adhering to the progressive rehabilitation plan is necessary to maximize the long-term regenerative potential of the treatment.
Recognizing Complications and Follow-Up
While PRP injections are considered a low-risk procedure, patients should be aware of signs that may indicate a complication. You should immediately contact your healthcare provider if you experience a fever, or if the pain and swelling at the injection site worsen significantly instead of gradually improving after the first 48 to 72 hours.
Signs of a possible infection include excessive or increasing warmth, spreading redness, or any pus-like drainage from the injection site. Although rare, a serious infection like septic arthritis requires immediate intervention to prevent joint damage. Persistent, severe pain that cannot be managed with acetaminophen also warrants a prompt medical evaluation.
Adhering to the scheduled follow-up appointments with your provider is important. These visits, typically occurring at intervals such as six weeks and three months, allow the medical team to assess the treatment’s efficacy and make any necessary adjustments to your rehabilitation plan. These check-ins guide the safe progression of your return to full activity.