Knee Osteoarthritis (OA) is a frequent degenerative joint disease that involves progressive loss of the articular cartilage, subchondral bone changes and joint inflammation, pain, and physical dysfunction [1]. It has a disproportionate impact with aging, obesity, previous joint injury, mechanical stress, and becoming an important cause of disability worldwide [2]. The prevalence of knee OA has been estimated to be 22.9% in population-based studies in those aged 40 years and older, which reflects the significant burden on healthcare systems and quality of life [3]. Traditional treatment involves: weight loss, exercise, analgesics, non-steroidal anti-inflammatory drugs (NSAIDs), intra-articular corticosteroid and hyaluronic acid injections (these treatments usually help ease pain rather than restore damaged tissues to the joint) [4]. Given the potential of PRP in its biological effects, it is a treatment option for knee OA patients who are suffering from symptomatic knee OA [5]. PRP is an autologous preparation of concentrated platelets that produce several growth factors and cytokines, having an effect on the inflammation, tissue repair, angiogenesis and synthesis of the extracellular matrix [6]. Such biological activities can be involved in the reduction of pain and improvement of the function of the joint following intra-articular administration [7]. Of particular clinical interest has been those with mild to moderate radiographic knee OA where delaying more invasive treatment may be possible by preserving remaining cartilage and improving symptoms [8].

However, there is mixed evidence of the clinical effectiveness of PRP. Earlier meta-analysis showed that PRP has a higher improvement in WOMAC score than HA (44.7% vs. 12.6%) [9]. On the other hand, a large, placebo-controlled randomized trial with 288 patients demonstrated no difference in pain reduction or cartilage-volume loss between PRP versus saline at 12 months [10]. This discrepancy in results could be partially attributed to different preparation methods of PRP, platelet concentration, leukocytes, frequency of injection, severity of the disease and evaluation of the results [11].More recently, research has been conducted to determine if there are any differences in response to LR-PRP and LP-PRP, and in a randomized fashion, there was only minimal evidence that the relative efficacy of the two differed [12]. Recent studies show that the type of patient, formulation of PRP, the stage of the disease, and the injection approach could have greater influence on treatment response than does its age [13]. In Europe there is currently a consensus that PRP is a suitable treatment for selected patients with Kellgren–Lawrence grade I–III knee OA in whom conservative treatment has failed [14]. Even though there are more and more clinical applications, there is still a lack of clarity about the size or longevity of the symptomatic improvement after PRP therapy.

Objective

To evaluate the efficacy of platelet-rich plasma therapy in improving pain and functional outcomes in patients with knee osteoarthritis.

This prospective interventional study was conducted at Ayub Medical College MTI, Abbottabad from June 2025 to June 2026 and included 300 patients with symptomatic knee osteoarthritis. Patients aged 40–75 years with clinically and radiologically confirmed knee osteoarthritis of Kellgren–Lawrence grade I–III, persistent knee pain for at least three months, and inadequate response to conservative treatment were included. Patients with inflammatory arthritis, previous knee replacement, recent intra-articular corticosteroid or hyaluronic acid injection, active infection, bleeding disorders, platelet dysfunction, anticoagulant therapy, severe anemia, malignancy, or Kellgren–Lawrence grade IV osteoarthritis were excluded. Data Collection After approval from the Institutional Ethical Review Committee, eligible patients were enrolled using a non-probability consecutive sampling technique. Demographic and clinical data including age, gender, body mass index, duration of symptoms, affected knee, comorbidities, and radiological grade were recorded. Autologous platelet-rich plasma was prepared from peripheral venous blood using standardized centrifugation and injected intra-articularly under aseptic conditions. Pain and functional status were assessed using the Visual Analog Scale (VAS) and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) at baseline and at 1, 3, and 6 months after treatment. Treatment response and adverse events were also documented. Statistical Analysis Data were analyzed using SPSS version 26.0. Continuous variables were expressed as mean±standard deviation, while categorical variables were presented as frequencies and percentages. Normality was assessed using the Shapiro–Wilk test. Changes in VAS and WOMAC scores over follow-up were evaluated using repeated-measures ANOVA or the Friedman test, as appropriate. Associations between treatment response and demographic or clinical characteristics were assessed using the independent-samples t-test, chi-square test, or Fisher’s exact test. Multivariable logistic regression analysis was performed to identify independent predictors of treatment response, and adjusted odds ratios with 95% confidence intervals were reported. A p-value ≤0.05 was considered statistically significant.

The mean age of the 300 patients was 57.2±9.8 years; 128 (42.7%) were male and 172 (57.3%) were female. Mean BMI was 28.7±4.6 kg/m² and mean symptom duration was 4.6±2.7 years. Diabetes was present in 81 (27.0%), hypertension in 126 (42.0%), and obesity in 108 (36.0%) patients. Unilateral involvement was seen in 214 (71.3%) and bilateral involvement in 86 (28.7%), while 261 (87.0%) had previously received conservative treatment.

Table 1. Baseline demographic and clinical characteristics of patients (n=300)

The right knee was treated in 158 (52.7%) patients and the left in 142 (47.3%). Kellgren–Lawrence grade I, II, and III osteoarthritis were present in 48 (16.0%), 156 (52.0%), and 96 (32.0%) patients, respectively. Crepitus was the most common finding, affecting 268 (89.3%), followed by morning stiffness in 236 (78.7%), restricted movement in 141 (47.0%), and joint swelling in 129 (43.0%). Baseline analgesic use was reported in 249 (83.0%) patients.

Table 2. Clinical and radiological characteristics of knee osteoarthritis

Pain and functional scores improved significantly following PRP therapy. Mean VAS decreased from 7.2±1.1 at baseline to 5.1±1.2 at 1 month, 3.7±1.3 at 3 months, and 4.0±1.4 at 6 months (p<0.001). WOMAC total score declined from 58.4±10.8 to 37.1±10.7, while pain, stiffness, and physical function scores improved from 13.2±2.6, 5.1±1.4, and 40.1±8.3 to 8.1±2.6, 3.1±1.3, and 25.9±8.2, respectively, at 6 months (all p<0.001).

Table 3. Changes in pain and functional outcomes following PRP therapy

Overall, 212 (70.7%) patients were classified as treatment responders, while 88 (29.3%) were non-responders. A ≥50% reduction in VAS was achieved by 192 (64.0%) patients and ≥30% improvement in WOMAC by 218 (72.7%). Analgesic use decreased in 201 (67.0%), and 225 (75.0%) reported satisfactory improvement. Adverse events occurred in 41 (13.7%), mainly injection-site pain in 29 (9.7%), local swelling in 14 (4.7%), and temporary stiffness in 11 (3.7%); no infections were recorded.

Table 4. Treatment response and adverse events at 6 months (n=300)

Poorer treatment response was independently associated with age ≥60 years (aOR 0.56, p=0.029), BMI ≥30 kg/m² (aOR 0.52, p=0.015), symptom duration >5 years (aOR 0.57, p=0.035), Kellgren–Lawrence grade III disease (aOR 0.33, p<0.001), and diabetes mellitus (aOR 0.49, p=0.010). Female gender, baseline VAS ≥7, and baseline WOMAC ≥50 were not significantly associated with response.

Table 5. Factors associated with treatment response to platelet-rich plasma therapy

In the current study, PRP proved to be effective in reducing pain and improving functional status in patients with knee OA. Mean VAS pain score decreased from 7.2±1.1 at baseline to 5.1±1.2 at one month, 3.7±1.3 at three months, and 4.0±1.4 at six months (p<0.001). Previous studies also showed a decrease in the mean VAS score from 7.55±1.54 at baseline to 2.92±1.37 at 6 months, and 2.65±1.41 at 9 months after serial PRP injections [16]. The results support the long-lasting analgesic effect of PRP in knee osteoarthritis (KOA) with symptoms. There was also a significant improvement in functionality as measured by the mean WOMAC total score, which dropped from 58.4±10.8 at baseline to 37.1±10.7 at 6 months. WOMAC pain, stiffness and physical function scores significantly improved. Previous research reported a comparable reduction in WOMAC score from 79.0±10.54 at baseline to 30.72±14.14 at six months and 24.42±15.82 at nine months (p<0.001) [16]. There has also been significant improvement reported at 3 and 6 months with controlled studies after PRP injections for pain, stiffness, function and total scores on the WOMAC at this time point [17]. Overall, 212 (70.7%) patients in the present study were treatment responders, and 192 (64.0%) patients had a ≥50% reduction in VAS pain and 218 (72.7%) patients had a ≥30% improvement in WOMAC score. The overall PRP responder rate of 73.6% at 6 months and 69.3% at 12 months reported in the previous study [18] was very similar to the present study. Another previous study reported the responder rate of 6 months, which means that the response rates can differ depending on the PRP preparation, injection protocol, patient characteristics, and severity of the disease [19]. There was minimal treatment effect from three months to six months (VAS score rose from 3.7±1.3 to 4.0±1.4, and WOMAC score rose from 34.8±10.2 to 37.1±10.7). Both, however, were still significantly above baseline. The beneficial effect of PRP has been shown to last for 6 to 12 months, with improvements in both VAS and WOMAC scores noted after follow-up [20]. This indicates that PRP can deliver clinically relevant medium-term relief in symptoms; but there may be a drop-off over time. Treatment response was different depending on patient characteristics. Obesity was an independent predictor of poor response in the current study (aOR 0.52; p=0.015). In previous studies, higher BMI related to a decrease in the WOMAC scores at 6 months (r=-0.496, p<0.001) and obese patients had worse 6 month WOMAC scores compared to non-obese patients [21]. A shorter duration of symptoms was also correlated with poor response (aOR 0.57; p=0.035). In previous studies, the patients with the shortest length of time since the onset of knee osteoarthritis symptoms showed significantly greater improvements with better outcomes at 6 and 9 months (p<0.001) [16]. Another significant predictor was radiological severity, with those patients with Kellgren–Lawrence grade III disease being significantly less likely to respond to treatment (aOR 0.33; p<0.001). In a similar study, radiographic severity of the OA was also an independent predictor of poor response, with ORs of 0.58 (95% CI 0.45–0.75; p<0.001) for grades II and III, and 0.50 (95% CI 0.39–0.65; p<0.001) for grade IV [20]. The results add to the overall safety of intra-ARTicular PRP, as the majority of complications seen were generally low grade, temporary and associated with the injection technique itself. There were some limitations of this study, such as being conducted in a single center, the absence of a control group and the short follow-up period of six months. PRP preparation and platelet concentration variations were not assessed and the use of patient-reported outcomes might have led to response bias. Further multicenter trials with uniform PRP preparation methods are necessary to validate these results.

It is concluded that platelet-rich plasma therapy was associated with significant improvement in pain, stiffness, and functional status in patients with knee osteoarthritis. Most patients achieved a favorable clinical response, with benefits remaining evident at six months and only mild adverse effects reported. Better outcomes were observed in younger, non-obese patients with shorter symptom duration and less advanced radiological disease. PRP may therefore be considered an effective and well-tolerated treatment option for selected patients with knee osteoarthritis.