Osteoarthritis (OA) of the knee is one of the most common causes of chronic disability in the aging population and is characterized by progressive degeneration of articular cartilage, subchondral bone remodeling, and synovial inflammation [1]. The global burden of OA is increasing due to rising life expectancy and prevalence of obesity, leading to a significant socioeconomic impact and reduced quality of life [2]. In India, knee OA constitutes a substantial proportion of orthopedic outpatient visits, especially among adults aged over 50 years, with a high incidence reported among females and urban dwellers [3].

Conventional management of knee OA includes pharmacological options such as nonsteroidal anti-inflammatory drugs (NSAIDs), corticosteroids, and viscosupplements, as well as non-pharmacological measures like physical therapy, weight reduction, and assistive devices [4]. However, these treatments are often palliative, aimed at symptom control, and do not alter the disease progression. Additionally, long-term NSAID use is associated with significant gastrointestinal, renal, and cardiovascular risks [5]. Therefore, there is an unmet need for disease-modifying intra-articular therapies that not only relieve symptoms but also aid in joint repair and regeneration.

Platelet-rich plasma (PRP), an autologous concentration of platelets in plasma, has emerged as a promising biological intervention in recent years due to its regenerative potential. PRP contains a high concentration of growth factors such as platelet-derived growth factor (PDGF), transforming growth factor-β (TGF-β), vascular endothelial growth factor (VEGF), and insulin-like growth factor (IGF), which are believed to promote cartilage repair, reduce inflammation, and enhance synovial cell proliferation [6,7]. Intra-articular administration of PRP is minimally invasive, well-tolerated, and can be prepared from the patient’s own blood, reducing immunogenic risks.

Several clinical studies have explored the efficacy of PRP in mild to moderate knee OA, with many reporting significant improvements in pain relief, joint function, and patient satisfaction [8]. Randomized controlled trials have even shown PRP to be superior to hyaluronic acid injections in some cohorts, particularly in younger patients with early-stage OA [9]. However, variability in PRP preparation methods, platelet concentration, number of injections, and follow-up duration has led to inconsistent results, necessitating more standardized, region-specific clinical investigations.

This study aims to evaluate the clinical efficacy of intra-articular PRP injections in patients with mild to moderate knee OA in a tertiary care center. By using validated outcome measures like the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) and Visual Analogue Scale (VAS) over a defined follow-up period, the study seeks to objectively assess improvements in pain and joint function. Additionally, the safety and tolerability of PRP administration will be documented to contribute to the growing body of evidence supporting regenerative therapy in musculoskeletal disorders [10].

Study Design and Setting

This was a prospective, interventional clinical study conducted at the Department of Orthopaedics, of Tertiary Care Hospital. Ethical approval was obtained from the Institutional Ethics Committee prior to initiation, and all participants provided written informed consent.

Study Population

Patients aged 40–70 years diagnosed with mild to moderate osteoarthritis (Kellgren-Lawrence grade I–III) of the knee, based on clinical evaluation and radiographic findings, were included in the study. Only patients with unilateral knee symptoms and a history of symptoms for more than 3 months were considered eligible.

Inclusion Criteria

• Age between 40 and 70 years
• Radiographic evidence of Kellgren-Lawrence grade I–III OA
• Persistent knee pain for at least 3 months
• Ability to understand and provide informed consent

Exclusion Criteria

• Advanced OA (Kellgren-Lawrence grade IV)
• History of inflammatory joint disease (e.g., rheumatoid arthritis, gout)
• Prior knee surgery or intra-articular injection in the last 6 months
• Coagulopathy, platelet disorders, or ongoing anticoagulant therapy
• Infection at the injection site or systemic infection
• Uncontrolled diabetes mellitus or immunosuppression

Sample Size

A total of 60 patients were recruited based on convenience sampling, and all received intra-articular PRP injections. No control group was included.

Preparation of Platelet-Rich Plasma

Approximately 20 ml of autologous peripheral blood was drawn from each patient under aseptic conditions into citrate-containing tubes. The blood was centrifuged using a two-spin technique:

• First spin: 1500 rpm for 10 minutes to separate red blood cells.
• Second spin: 3500 rpm for 10 minutes to concentrate platelets.

The resulting 3–5 ml of PRP was extracted and injected intra-articularly into the affected knee under strict aseptic precautions. No activator was used prior to injection.

Intervention Protocol

Each patient received a total of three intra-articular PRP injections, administered at weekly intervals. Post-procedure, patients were advised relative rest for 24 hours and avoidance of strenuous activity for one week after each injection. No other intra-articular treatments or systemic anti-inflammatory medications were permitted during the follow-up period.

Outcome Measures

Clinical evaluation was conducted at baseline and at 1 month, 3 months, and 6 months post-treatment using the following validated scoring systems:

Out of 60 patients enrolled in the study, 35 (58.3%) were female and 25 (41.7%) were male. The mean age of the participants was 56.2 ± 6.8 years. Most patients had Kellgren-Lawrence grade II OA (56.7%), followed by grade III (28.3%) and grade I (15%).

Table 1: Baseline Demographic and Clinical Profile of Study Participants

                                                Change in VAS Scores Over Time

VAS scores showed a statistically significant reduction from baseline to the 6-month follow-up. The mean VAS score decreased from 7.3 ± 1.0 at baseline to 3.4 ± 1.2 at 6 months (p < 0.001), indicating a marked improvement in pain.

Table 2: Visual Analogue Scale (VAS) Scores Over Time

                                            Change in WOMAC Total Scores

Total WOMAC scores showed significant improvement, dropping from 62.1 ± 9.2 at baseline to 31.8 ± 7.9 at 6 months (p < 0.001). Improvements were consistent across pain, stiffness, and function domains.

Table 3: WOMAC Total and Domain Scores Over Time

                             Effect of KL Grade on Treatment Response

Patients with grade I and II OA showed more improvement compared to grade III patients. At 6 months, VAS and WOMAC scores in grade I–II patients were significantly lower than in grade III patients (p < 0.05).

Table 4: Comparison of Outcome Scores at 6 Months by KL Grade

This clinical study aimed to evaluate the therapeutic efficacy of intra-articular platelet-rich plasma (PRP) injections in patients with mild to moderate osteoarthritis (OA) of the knee. The results revealed significant improvement in pain relief and functional outcomes over a 6-month follow-up period. Notably, both Visual Analogue Scale (VAS) and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) scores demonstrated a statistically significant decline from baseline, indicating the beneficial impact of PRP in alleviating symptoms and enhancing joint function.

Knee OA is a degenerative joint disease characterized by progressive cartilage loss, subchondral bone remodeling, osteophyte formation, and chronic synovial inflammation. Traditional treatment modalities, including NSAIDs, corticosteroids, and hyaluronic acid injections, offer only symptomatic relief and are often associated with systemic side effects or diminishing returns over time. In contrast, PRP is an autologous biologic product that harnesses the body’s own healing potential by concentrating platelets and growth factors that are believed to stimulate tissue regeneration, modulate inflammation, and slow cartilage degradation [11].

In this study, the most notable improvement was observed in the first three months following PRP administration, with sustained benefits seen at 6 months. The mean VAS score reduced from 7.3 to 3.4, while the total WOMAC score decreased from 62.1 to 31.8, both with high statistical significance. These findings are consistent with previously published randomized controlled trials and meta-analyses, which have reported favorable outcomes for PRP in terms of both pain reduction and functional improvement in early OA cases [12]. The magnitude of improvement in WOMAC domains—particularly in function and pain—underscores PRP’s potential to not only control symptoms but also improve quality of life.

The underlying mechanism through which PRP exerts its effect is multifactorial. Growth factors released by activated platelets, such as transforming growth factor-β (TGF-β), platelet-derived growth factor (PDGF), and vascular endothelial growth factor (VEGF), are known to stimulate chondrocyte proliferation, enhance matrix synthesis, and suppress inflammatory cytokines in the joint microenvironment [13]. Moreover, PRP is believed to improve the viscoelasticity of synovial fluid and provide an anti-inflammatory milieu that facilitates joint homeostasis [14].

Subgroup analysis in the present study showed that patients with Kellgren-Lawrence (KL) grade I and II OA had better clinical responses compared to those with grade III. This aligns with the hypothesis that early degenerative changes are more amenable to biological repair strategies, while advanced structural damage may limit the regenerative potential of biologics [15]. This stratification underscores the importance of patient selection when considering PRP therapy, as outcomes may vary based on disease severity.

Safety and tolerability were also assessed during the study period. No major adverse events were reported, affirming the safety profile of PRP as an autologous product. Minor adverse events such as transient swelling and post-injection discomfort resolved spontaneously within 24–48 hours, which is consistent with existing safety data [16].

Despite the encouraging results, certain limitations merit discussion. The study lacked a control group, which limits the ability to compare PRP’s efficacy directly with placebo, corticosteroids, or hyaluronic acid. Additionally, PRP preparation protocols, including the concentration of platelets and presence or absence of leukocytes, were standardized in this study but may vary widely in clinical practice, leading to inconsistent results across studies [17]. The duration of follow-up was limited to 6 months, and long-term efficacy beyond this period remains unknown.

The number of injections and the interval between them are also subjects of ongoing debate. Some studies suggest that two or three injections provide optimal benefit, while others report comparable results with a single injection [18]. In this study, three weekly injections were used, resulting in sustained symptomatic improvement. Further comparative studies may help define the ideal dosage and regimen to maximize therapeutic benefit while minimizing cost and patient burden.

Another area warranting attention is the potential role of imaging modalities in assessing structural outcomes. While this study focused on subjective clinical scores, advanced imaging such as MRI could provide objective data on cartilage preservation or regeneration, allowing a more comprehensive evaluation of PRP’s disease-modifying capabilities [19].

Intra-articular PRP injections significantly improved pain and function in patients with mild to moderate knee osteoarthritis over a 6-month period. The treatment was well-tolerated, with no major adverse effects. The greatest clinical benefit was observed in patients with early-stage OA, suggesting the importance of timely intervention. PRP represents a safe and promising biological therapy, offering an effective alternative to conventional pharmacologic approaches. Further multicenter studies with longer follow-up and imaging validation are needed to establish standardized protocols and assess long-term structural outcomes.

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