Biological Response to Platelet-rich Plasma and Corticosteroid Injections

The goal is to determine how two different injections, corticosteroid and platelet-rich plasma, are used to treat patients with knee osteoarthritis may affect a patient's pain and function. Secondarily, the investigators are also interested in knowing how the two types of injections that will be given may affect what happens in the joint cartilage. The participants will receive one of the two injection types at the initial visit. There will be surveys to complete (around 10 questions) about the participants' knee and overall function. The investigators will ask these same questions on seven separate occasions. In addition, the investigators will ask the participants to provide blood and urine samples at our clinic before the first knee injection and before any other injection that is needed over the course of the study. During the injections, synovial fluid will be aspirated from the participants' knee at the initial visit and the one month visit. If the participants decide to go to surgery to help relieve the pain from osteoarthritis at any point during the study, the investigators will collect the material from the participants' knee that would be normally discarded as medical waste.

Previous studies have indicated that concentrations of inflammatory and degradative biomarkers in patient serum, urine, and synovial fluid may provide insight into OA pathophysiology. To our knowledge, no study has been performed to assess the impact of intra-articular PRP injection upon fluid concentrations of a comprehensive panel of proposed OA-related biomarkers. In this study, the investigators will evaluate the impact of intra-articular PRP injection upon markers of cartilage matrix turnover, inflammatory mediators, degradative enzymes, inhibitors of degradative enzymes, and markers of bone metabolism in serum, urine, and synovial fluid of knee OA patients.

Knee osteoarthritis (OA) is an extremely common cause of disability, with a global prevalence of 22.9% in adults aged 40 and over. OA is a whole-joint disease characterized by progressive degradation of articular cartilage, chronic inflammation of joint tissue, and subchondral bone remodeling, resulting in severe pain and decreased mobility in patients.

No cure currently exists for OA, and treatment is aimed at symptomatic management and prevention of disease progression. Currently, this consists of:

1. Initial conservative treatment for osteoarthritis across all levels of radiographic disease severity includes activity modification, oral analgesic or anti-inflammatory medications, non-supervised or supervised (e.g., physical therapy) exercise, and occasionally bracing.
2. Injection therapies have been used in the treatment of osteoarthritis for more than 60 years. Medical corticosteroids have served as a gold standard for symptom management as an intra-articular injection, but concerns have always existed around the potential for either the steroid medication (which suppresses both repair and inflammation processes) or the local anesthetic co-administered with the steroid to contribute to degradation of joint cartilage over time. Alternative substances have been developed to address the joint environment - with an intent to improve symptoms, while decreasing the potential for joint degeneration. These alternative medications include viscosupplements (hyaluronic acid analogues) and biological agents (platelet-rich plasma, or stem cell therapies).
3. Surgical interventions include arthroscopy for concurrent symptomatic meniscus tears or unstable cartilage that contribute to mechanical symptoms, osteotomy (realignment) surgery for active patients with single compartment arthritis, and arthroplasty (joint replacement) for patients with more limited activity goals, severe arthritis, and temporary-but not sustained---pain relief with the conservative treatments described in #1 and #2.

Intra-articular injection of a corticosteroid has been shown to be effective in providing short-term relief of knee OA symptoms, possibly due to anti-inflammatory and immunosuppressive effects. Repeated corticosteroid injections have thus become the standard of care for patients with mild to moderate knee OA.

Intra-articular injection of platelet-rich plasma (PRP) has emerged as a promising alternative to corticosteroid injection in knee OA patients. Studies have indicated that PRP is safe and may provide benefits such as pain relief, improved knee function, and enhanced quality of life. Moreover, PRP injection has been shown to provide longer-lasting symptomatic attenuation, with clinically significant improvement observed for as long as 12 months post-injection.

Previous studies have indicated that concentrations of inflammatory and degradative biomarkers in patient serum, urine, and synovial fluid may provide insight into OA pathophysiology. To the investigators' knowledge, no study has been performed to assess the impact of intra-articular PRP injection upon fluid concentrations of a comprehensive panel of proposed OA-related biomarkers. In this study, the investigators will evaluate the impact of intra-articular PRP injection upon markers of cartilage matrix turnover, inflammatory mediators, degradative enzymes, inhibitors of degradative enzymes, and markers of bone metabolism in serum, urine, and synovial fluid of knee OA patients.

Eligibility Criteria:
Inclusion Criteria:

* Patients aged 40 and over, presenting with a knee disorder of at least one knee
* Patients eligible for use of either corticosteroid or biological agent for treatment of moderate or severe (but not end-stage) knee osteoarthritis
* KL grade of 2-3

Exclusion Criteria:

* Subjects less than 40 years of age
* Previous reconstructive knee surgery
* Participating in another clinical trial
* Unable to receive corticosteroid injections (i.e., allergies, adverse reactions, etc.)
* Unable to sign informed consent
* Pregnant or plan to become pregnant