Platelet-rich plasma facilitates earlier functional recovery and return to sport in traumatic meniscal repair: a retrospective cohort study

Abstract

Purpose

To investigate the clinical efficacy of arthroscopic repair combined with platelet-rich plasma (PRP) injection for traumatic meniscal tears.

Methods

A retrospective cohort study included patients who underwent arthroscopic repair for traumatic meniscal tears between January 2023 and August 2024. Clinical outcomes were evaluated preoperatively and at 6 and 12 months postoperatively using the International Knee Documentation Committee (IKDC) score, Tegner activity scale (Tegner scale), and visual analogue scale (VAS). MRI healing rate, return to sport (RTS) outcomes, and postoperative satisfaction were evaluated. Subgroup analyses were conducted for patients with preoperative bone marrow edema (BME).

Results

A total of 96 patients were included (48 per group), with comparable baseline characteristics. At 6 months, the PRP group demonstrated significantly greater improvements in IKDC score, Tegner scale and VAS than the surgery-alone group (p < 0.001, p = 0.036, and p < 0.001, respectively), with differences exceeding the minimal clinically important differences (MCIDs). MRI healing rate was higher in the PRP group (p = 0.014). By 12 months, improvements in IKDC score and VAS remained superior in the PRP group though differences no longer exceeded MCIDs. Tegner scale and MRI healing rates were comparable (p = 0.265 and 0.088, respectively). The PRP group achieved superior RTS outcomes. Satisfaction (≥ satisfied) was high in both groups (95.8% vs. 89.6%). In the PRP group, postoperative IKDC scores did not differ significantly between patients with and without BME, whereas in the surgery-alone group, scores were significantly lower in those with BME.

Conclusions

PRP augmentation for traumatic meniscal repair may provide clinically improvements at 6 months postoperatively, including better IKDC score, Tegner scale, and VAS, a higher meniscal healing rate, and facilitate earlier RTS. However, these benefits diminished by 12 months, with functional differences falling below the MCID and no sustained difference in healing rate. Patients with preoperative BME may derive greater functional benefit from adjunctive PRP treatment.

Background

Meniscal tear is a common knee disorder worldwide and a frequent cause of pain and functional limitation. The meniscus plays an essential role in load transmission, shock absorption, joint stability, and force distribution. Traumatic meniscal tear is typically associated with a clear knee trauma event, accompanied by sudden onset of knee pain [1]. Meniscal damage may accelerate cartilage degeneration and increase the risk of knee osteoarthritis [1–3].

For repairable lesions, meniscal repair is preferred, as it restores meniscal integrity, preserves biomechanical function, and delays joint degeneration [1, 4]. However, meniscal healing is often prolonged, particularly in the red–white zone, which is associated with lower vascularity and higher failure rates [5–7]. Consequently, early postoperative pain, lengthy recovery duration, specialized rehabilitation requirements, and poor adherence are key factors that hinder functional recovery [8, 9].

Bone marrow edema (BME) is commonly observed after knee trauma, with reported prevalence ranging widely from 8% to 89% [10]. BME may result from micro-trabecular injury or altered joint biomechanics following meniscal damage [7, 11]. Clinically, BME is associated with pain, functional impairment, and increased risk of cartilage degeneration and osteoarthritis, potentially affecting postoperative recovery after meniscal repair [12, 13].

Platelet-rich plasma (PRP) is an autologous blood product enriched with platelets and bioactive factors that has been widely used as a biological adjunct to enhance tissue repair [14–16]. Platelet-derived growth factors promote meniscal cell proliferation, matrix synthesis, and mechanical integrity, while PRP may also modulate the inflammatory response by downregulating pro-inflammatory cytokines, thereby reducing pain and facilitating early recovery [17, 18]. In addition to its established applications in cartilage, tendon, ligament, and osteoarthritic conditions, PRP has been proposed to influence subchondral inflammation and metabolic repair, suggesting a potential benefit in patients with BME [19–21]. However, in meniscal repair, some studies have reported improved early clinical outcomes and healing rates with PRP augmentation [22–25], whereas other studies have found limited mid to long-term benefit [19, 26]. Therefore, it is necessary to further investigate the role of PRP in traumatic meniscal repair.

The purpose of this study was to evaluate the clinical outcomes of arthroscopic repair combined with PRP injection for traumatic meniscal tears. We hypothesized that PRP augmentation would improve early postoperative recovery after traumatic meniscal repair, and that patients with preoperative BME might derive greater clinical benefit.

Methods

Ethical approval

This retrospective cohort study included patients treated for traumatic meniscal tears between January 2023 and August 2024. The study was approved by the institutional ethics committee of the Second Affiliated Hospital of Xi'an Jiaotong University (Approval No. 2025-237).

Inclusion and exclusion criteria

Inclusion criteria

(1) history of traumatic knee injury; (2) Magnetic Resonance Imaging (MRI)-confirmed meniscal tears; (3) age 18–50 years; (4) undergoing arthroscopic meniscal repair; (5) Kellgren–Lawrence grade ≤ 2.

Exclusion criteria

(1) concomitant ligament injury, fracture, or other intra-articular pathology; (2) arthritic changes (Kellgren–Lawrence grade > 2); (3) previous surgery on the affected knee; (4) incomplete clinical data or follow-up period < 12 months; (5) severe systemic disease.

Case selection

Consecutive patients with traumatic meniscal tears who met the inclusion criteria between January 2023 and August 2024 were included. 229 consecutive patients with traumatic meniscal tears were screened. 103 patients met the inclusion criteria, and 7 patients were lost to follow-up. 96 patients were included in the final analysis (Fig. 1).

Fig. 1.

Flowchart illustrating patient inclusion in the study

Patient selection for PRP

All patients met the same surgical indications. PRP augmentation was offered as an optional adjunctive procedure. The final decision was made based on patient preference after informed discussion, and was not related to tear characteristics or injury severity. Patients were categorized into the Surgery-alone group (n = 48) and the PRP group (n = 48). Baseline characteristics including age, sex, BMI, injury side, injury-to-surgery time, follow-up time and injury mechanism were collected.

Preparation and application of PRP

PRP were prepared using a single-use PRP preparation kit (Model: PG-PRP-01; Registration No.: National Medical Device Registration 20163661321) provided by Weigao Group Medical Polymer Co., Ltd. (Weihai, China).

A total of 50 mL of peripheral venous blood was drawn from the antecubital vein into a specialized vacuum collection tube pre-filled with 5 mL of sodium citrate injection. Non-activated leukocyte-rich platelet-rich plasma (L-PRP) was obtained via a double centrifugation system, which may express more IL-1Ra, IL-4, and IL-8 and contribute to the initiation of the healing cascade through cytokine release and macrophage recruitment [27]. The PRP was injected intra-articularly at the end of arthroscopic repair, to ensure sustained post-operative release of growth factors.

Surgical procedure and rehabilitation protocol

All surgeries were performed by senior orthopaedic surgeons experienced in arthroscopic techniques under general or combined spinal–epidural anesthesia. With the patient in the supine position and a tourniquet applied, standard anterolateral and anteromedial portals were established. All meniscal repairs were performed using a standardized procedure, including necessary shaping, reduction, and suture fixation. Patients with discoid meniscus first underwent saucerization to restore normal meniscal morphology, followed by meniscal repair. After confirming repair stability, achieving hemostasis, and removing excess fluid from the joint cavity by compression and negative pressure aspiration, 5 mL PRP was injected in the PRP group via the arthroscopic portal. Portals were closed and compression dressing applied.

Postoperatively, a knee brace was used in extension for 2 weeks with early straight-leg raises and ankle pumps. Controlled flexion to 120° began at 3–4 weeks with brace protection, and progressive weight-bearing was permitted. At 4–12 weeks, patients returned to daily activities. After 12 weeks, patients were encouraged to attempt return to sport, with individualized protocols developed based on knee function, psychological status, and sports demands.

Clinical outcomes

Follow-up evaluations were conducted through outpatient visits, online questionnaires, or telephone interviews by sports medicine physicians not involved in surgery. The clinical outcomes were evaluated preoperatively and at 6 months, 12 months postoperatively.

The primary outcome was improvement in the International Knee Documentation Committee (IKDC) subjective score during follow-up, with the minimal clinically important difference (MCID) of 9.8 points [28]. Secondary outcomes included Tegner activity scale (Tegner scale), visual analogue scale (VAS), return to sport (RTS) rate, RTS time, return to preinjury level (RTPL) rate, MRI healing rate and patient satisfaction. The MCIDs for the Tegner scale and VAS were 0.5 and 1.5 points, respectively [18, 29]. To describe the magnitude of postoperative change within individuals, changes in clinical outcomes from baseline to postoperative follow-up were calculated as follows [30]:

• Improvement in function: ΔIKDC-6 M/12 M = IKDC-6 M/12 M—IKDC-Pre

• Decrease in activity level: ΔTegner-6 M/12 M =|Tegner-6 M/12 M—Tegner-Pre|

• Improvement in pain: ΔVAS-6 M/12 M =|VAS-6 M/12 M—VAS-Pre|

RTS was defined as the return to any regular physical activity (not necessarily the same as preinjury) without pain or functional limitation, while RTPL required frequency, duration, and intensity comparable to or exceeded the preinjury level [31].

MRI healing was evaluated at 6 months and 12 months postoperatively according to the Stoller and Crues three-grade classification [32, 33]. Grade 1 was defined as an intra-meniscal signal not extending to the articular surface, grade 2 as a linear intra-meniscal signal not extending to the articular surface, and grade 3 as a signal extending to or communicating with the articular surface. Based on previous literature, we define grade 1 and grade 2 as healed, and grade 3 as unhealed [25].

Patient satisfaction was recorded using a 5-point Likert scale (“very satisfied,” “satisfied,” “neutral,” “dissatisfied,” “very dissatisfied”).

To explore the potential influence of BME on clinical outcomes, patients were stratified into BME and non-BME subgroups according to preoperative MRI evaluation. An exploratory subgroup analysis was conducted to compare postoperative outcomes between the PRP and surgery-alone groups within each subgroup, as well as to assess outcomes between BME and non-BME patients within the same treatment group.

Complications and adverse events

All complications and adverse events were documented throughout follow-up. Treatment failure was defined as:

1. IKDC improvement below MCID compared with baseline;

2. Re-tear or persistent pain symptoms requiring secondary surgery.

Power consideration

To assess whether the available sample size was sufficient to detect a clinically meaningful difference, a post-hoc detectable difference analysis was conducted using the MCID of 9.8 points for the IKDC score and the observed pooled standard deviation at 12 months, the corresponding effect size (Cohen’s d) was approximately 1.01. With 48 patients included in each group and a two-sided alpha level of 0.05, the statistical power to detect the MCID was approximately 99%.

Statistical analysis

All data were expressed as mean ± standard deviation (SD). Continuous variables are presented as mean ± standard deviation. Data normality was assessed using the Kolmogorov–Smirnov test. For normally distributed data, paired or independent-samples t-tests were used as appropriate, and analysis of variance was applied for comparisons involving more than two groups. Non-normally distributed data were analyzed using the Wilcoxon signed-rank test or the Mann–Whitney U test. Categorical variables were compared using the chi-square or Fisher’s exact test, as appropriate. A two-sided p value < 0.05 was considered statistically significant. All statistical analyses were performed using SPSS version 27.0 (IBM Corp., Armonk, NY, USA).

Results

Descriptive statistics

A total of 96 patients were analyzed: 60 males and 36 females. The mean age was 31.68 ± 8.85 years, BMI 23.86 ± 3.66 kg/m², injury-to-surgery time 8.47 ± 11.38 weeks and follow-up time 18.08 ± 4.64 months. There were no significant differences between the two groups in baseline characteristics (Table 1).

Table 1.

Comparison of baseline demographic data

Variablesa	All (n = 96)	Group 1b(n = 48)	Group 2b(n = 48)		p valued
Age, years	31.68 ± 8.85	32.81 ± 9.05	30.54 ± 8.59		0.241
Sexc, male/female	60/36	26/22	34/14		0.092e
Body mass index, kg/m2	23.86 ± 3.66	23.39 ± 3.21	24.34 ± 4.04		0.217
Injury-to-Surgery, weeks	8.47 ± 11.38	8.24 ± 10.04	8.71 ± 12.68		0.953
Follow-up, months	18.08 ± 4.64	18.50 ± 5.16	17.67 ± 4.08		0.546
MOIc, contact/non-contact	14/82	9/39	5/43		0.247e
Sidec, left/right	41/55	18/30	23/25		0.302e
Meniscus involvedc, med/lat/both	40/54/2	18/29/1	22/25/1		0.763f
WBC count	6.24 ± 1.27	6.24 ± 1.33	6.25 ± 1.23		0.668
Hb level	147.36 ± 13.63	144.56 ± 13.04	150.17 ± 13.76		0.055
Platelet count	250.44 ± 50.23	243.67 ± 45.73	257.21 ± 63.98		0.303
Repair techniquec					0.050f
All-inside	75	40		35
Inside-out	3	2		1
All-inside + Inside-out	14	2		12
All-inside + Outside-in	4	4		0

Abbreviations: MOI Mechanism of injury, WBC White blood cell, Hb hemoglobin

^aThe data are presented as the mean and standard deviation, otherwise noted separately

^bGroup 1, Surgery-alone Group; Group 2, PRP Group

^cThe data are presented as number of patients

^dStatistical analyses were conducted using Mann-Whitney U tests, otherwise noted separately

^eStatistical analyses were performed using the Chi-squared test

^fStatistical analyses were performed using the Fisher’s exact test

Radiological assessment

Kellgren–Lawrence grading was used to evaluate osteoarthritis. Based on MRI findings, experienced musculoskeletal radiologists assessed the location and type and graded the severity according to the Stoller classification. BME and discoid meniscus was also assessed. Relevant imaging data are presented in Table 2.

Table 2.

Comparison of radiographic parameters

Variablesa	All (n = 96)	Group 1b(n = 48)	Group 2b(n = 48)	p valued
K-L grade, 0/1/2	47/33/16	23/17/8	24/16/8	0.975
Stoller grade, 2/3	5/91	5/43	0/48	0.056e
Type of tear				0.714
Oblique	30	16	14
Longitudinal	24	11	13
Transverse	14	9	5
Bucket-Handle	15	6	9
Complex	13	6	7
Tear Zone, Red/Red-White	56/40	27/21	29/19	0.679
Site of Lesion, single/multiple	56/40	31/17	25/23	0.214
Outerbridge grade, low/highc	92/4	47/1	45/3	0.618e
BME, yes/no	44/52	21/27	23/25	0.682
DM, yes/no	23/73	15/33	8/40	0.094

Abbreviations: K-L grade Kellgren–Lawrence grade, BME Bone Marrow Edema, DM Discoid Meniscus

^aThe data are presented as number of patients, otherwise noted separately

^bGroup 1, Surgery-alone Group; Group 2, PRP Group

^cLow grade: Outerbridge grade 0-II; High grade: Outerbridge grade III

^dStatistical analyses were performed using the Chi-squared test, otherwise noted separately

^eStatistical analyses were performed using the Fisher’s exact test

Functional outcomes

Preoperative IKDC score, Tegner scale and VAS were comparable between groups (Detailed data are presented in Table 3 and Fig. 2).

Table 3.

Comparison of functional outcomes

Variablesa	Group 1b (n = 48)	Group 1 p valuec	Group 2b (n = 48)	Group 2 p valuec	Between group p valued
IKDC subjective score
IKDC-Pre	31.87 ± 12.26		30.36 ± 6.96		0.786
IKDC-6M	77.19 ± 10.19	< 0.001	88.77 ± 5.90	< 0.001	< 0.001
IKDC-12M	89.68 ± 7.92	< 0.001	96.10 ± 4.19	< 0.001	< 0.001
ΔIKDC-6M	45.31 ± 11.93		58.40 ± 8.69		< 0.001
ΔIKDC-12M	57.81 ± 13.21		65.85 ± 8.03		< 0.001
Tegner activity scale
Tegner-Pre	5.40 ± 1.14		5.46 ± 0.80		0.832
Tegner-6M	3.56 ± 1.34	< 0.001	4.10 ± 0.83	< 0.001	0.036
Tegner-12M	4.52 ± 1.30	< 0.001	4.81 ± 0.79	< 0.001	0.265
ΔTegner-6M	1.83 ± 1.36		1.35 ± 0.76		0.018
ΔTegner-12M	0.87 ± 1.04		0.65 ± 0.60		0.241
VAS
VAS-Pre	6.69 ± 1.11		7.08 ± 0.68		0.035
VAS-6M	2.79 ± 0.97	< 0.001	1.29 ± 0.97	< 0.001	< 0.001
VAS-12M	1.02 ± 0.96	< 0.001	0.35 ± 0.60	< 0.001	< 0.001
ΔVAS-6M	3.90 ± 1.12		5.79 ± 1.09		< 0.001
ΔVAS-12M	5.67 ± 1.29		6.73 ± 0.96		< 0.001

Abbreviations: IKDC International knee documentation committee, VAS Visual analogue scale

^aThe data are presented as the mean and standard deviation, otherwise noted separately

^bGroup 1, Surgery-alone Group; Group 2, PRP Group

^cThe p value represents the comparison between postoperative time points and preoperative scores

^dStatistical analyses were conducted using Mann–Whitney U tests, otherwise noted separately

Fig. 2.

Between‐group comparison of functional outcomes. a IKDC subjective score, b ΔIKDC score, c Tegner activity scale, d ΔTegner scale, e VAS and f ΔVAS. IKDC, International Knee Documentation Committee. Symbols above the standard error bars indicate the significance of differences between the surgery-alone group and PRP group. ns, not significant; * p < 0.05; ** p < 0.01; *** p < 0.001

At 6 months postoperatively, the PRP group demonstrated significantly higher IKDC score and greater ΔIKDC score compared with the surgery-alone group, with between-group differences exceeding the MCID. The PRP group achieved higher Tegner scale and ΔTegner-6 M. However, the between- group difference in ΔTegner-6 M was less than the MCID. The PRP group showed significantly greater pain relief, with between-group differences in VAS and ΔVAS exceeding the MCID.

At 12 months, IKDC score and ΔIKDC-12 M remained higher in the PRP group, though the between-group differences fell below the MCID. No significant differences were observed in Tegner scale or ΔTegner-12 M between groups. Both groups remained below pre-injury levels, with differences exceeding the MCID. The between-group differences in VAS and ΔVAS were statistically significant but no longer exceeded the MCID.

Meniscal healing

At 6 months postoperatively, the PRP group showed improved meniscal healing compared with the surgery-alone group (10/22/16 vs. 4/16/28 for grades 1/2/3), with a higher overall healing rate (66.7% vs. 41.7%). By 12 months, healing outcomes were comparable between groups (13/22/13 in PRP group vs. 7/20/21 in surgery-alone group), and the healing rates were comparable (Table 4).

Table 4.

MRI evaluation, RTS and postoperative satisfaction

Variablesa	All (n = 96)	Group 1b(n = 48)	Group 2b(n = 48)	p valuee
MRI healing, healed/unhealedc
6 months postoperatively	52/44	20/28	32/16	0.014
12 months postoperatively	62/34	27/21	35/13	0.088
RTS Time, monthsd	6.74 ± 2.03	7.55 ± 2.43	6.06 ± 1.72	0.001f
RTS Rate (%)	88/96, 91.7%	40/48, 83.3%	48/48, 100%	0.006g
RTPL Rate (%)	31/96, 32.3%	14/48, 23.2%	17/48, 35.4%	0.968
Postoperative satisfaction (≥ Satisfied, %)	89/96, 92.7%	43/48, 89.6%	46/48, 95.8%	0.435g

Abbreviations: RTS Return to sport, RTPL Return to pre-injury level

^aThe data are presented as n/total, (%), otherwise noted separately

^bGroup 1, Surgery-alone Group; Group 2, PRP Group

^cThe data are presented as number of patients

^dThe data are presented as the mean and standard deviation

^eStatistical analyses were performed using the Chi-squared test, otherwise noted separately

^fStatistical analyses were conducted using Mann-Whitney U tests

^gStatistical analyses were performed using the Fisher’s exact test

Return to sport and surgical satisfaction

By 12 months, 88 patients (91.7%) returned to sport, and 31 patients (32.3%) returned their pre-injury activity level. In the surgery-alone group, 40 of 48 patients (83.3%) returned to sport, with a mean return time of 7.55 ± 2.43 months, and 14 patients (23.2%) reached their pre-injury activity level. All patients in the PRP group returned to sport, with an average return time of 6.06 ± 1.72 months, and 17 patients (35.4%) returned their pre-injury activity level.

Overall, 89 of 96 patients (92.7%) reported being satisfied or very satisfied with the surgery, while 6.3% (6/96) rated their satisfaction as moderate. Satisfaction rate was 95.8% in the PRP group and 89.6% in the surgery-alone group.

Subgroup analysis of BME

Patients with BME had significantly lower preoperative IKDC score in both surgery-alone and PRP group (p = 0.004 and 0.001, respectively). In the surgery-alone group, patients with BME showed significantly lower IKDC score at 6 and 12 months postoperatively compared to those without BME. In the PRP group, there was no significant difference in IKDC score between patients with BME and those without BME.

The PRP group consistently demonstrated superior postoperative IKDC score compared to the surgery-alone group, irrespective of concomitant BME (Table 5).

Table 5.

Comparison of IKDC score by preoperative BME status

Time points	Subgroupsa	Group 1b	Group 2b	p valuec
IKDC-Pre	Non-BME	35.89 ± 12.17	33.52 ± 7.10	0.569
	BME	26.71 ± 10.55	26.94 ± 4.98	0.179
	p valued	0.004	0.001
IKDC-6 M	Non-BME	81.79 ± 7.92	89.88 ± 6.23	< 0.001
	BME	71.26 ± 9.85	87.56 ± 5.40	< 0.001
	p valued	< 0.001	0.153
IKDC-12 M	Non-BME	93.27 ± 5.41	96.87 ± 3.95	0.009
	BME	85.06 ± 8.34	95.50 ± 4.41	< 0.001
	p valued	< 0.001	0.265

Abbreviations: IKDC International knee documentation committee

^aThe data are presented as the mean and standard deviation

^bGroup 1, Surgery-alone Group; Group 2, PRP Group

^cThe p value represents the comparison in Non-BME or BME subgroups

^dThe p value represents the comparison in Group 1 or Group 2

Statistical analyses were conducted using Mann-Whitney U tests

Discussion

The most important finding of this study is that for patients with traumatic meniscal tears in the red or red–white zones, PRP augmentation enhances early postoperative functional recovery and pain relief, with clinical improvements exceeding the MCID, and results in a higher MRI healing rate and superior RTS outcomes. However, the early benefits of PRP diminished over time, patients who underwent isolated meniscal repair progressively regained knee function during follow-up.

In the present study, PRP augmentation was associated with greater improvement in IKDC score at 6 months postoperatively, suggesting a clinically meaningful early functional advantage. Similar early benefits were reported by Kaminski et al. [25], with higher short-term healing rates and improved functional outcomes compared with repair alone. These benefits may be attributed to the high concentrations of PDGF, TGF-β, and VEGF in PRP, which promote fibrocartilage cell proliferation and extracellular matrix synthesis [14, 15, 34]. Traumatic tears located in the red or red–white zones, as included in the present cohort, may possess greater intrinsic healing capacity [1, 35], potentially allowing PRP to exert a greater adjunctive effect.

At 12 months, although the PRP group maintained statistical superiority (p < 0.001), the between-group differences in IKDC score and ΔIKDC fell below the MCID, suggesting that PRP augmentation may primarily accelerate early recovery rather than result in sustained long-term functional superiority [36].

PRP augmentation was also associated with greater pain reduction at 6 months postoperatively, with differences exceeding the MCID, indicating a clinically meaningful early analgesic benefit. This early pain relief may have contributed to the earlier RTS observed in the PRP group. Meanwhile, continued pain reduction in the surgery-alone group led to convergence of outcomes, suggesting that the analgesic effect of PRP may be most pronounced in the early postoperative period. This temporal pattern is consistent with prior evidence indicating limited long-term superiority of PRP for pain relief [37].

Regarding the recovery of activity levels, the findings showed a certain degree of complexity. PRP augmentation was associated with higher Tegner scale at 6 months, while both groups remained below pre-injury levels, indicating incomplete functional recovery. The higher early activity level in the PRP group may be related to improved pain control and subjective knee function [38], although actual activity intensity remains constrained by the physiological healing process. By 12 months, activity levels were comparable between groups and remained lower than pre-injury status, consistent with previous reports following meniscal repair [22, 39].

The overall RTS rate was high (91.7%, 88/96), yet RTPL rate was only 32.3% (31/96). This finding aligns with prior studies reporting a discrepancy between RTS and RTPL after meniscal repair and other knee surgeries [22, 40]. MRI at 6 months demonstrated a higher healing rate in the PRP group, which may be partly attributed to the healing stimulus of PRP. However, the healing rates at 12 months became comparable between groups, suggesting that the beneficial effect of PRP may be primarily limited to early healing in the red or red–white zones. Notably, functional recovery and patient-reported outcomes may be more clinically relevant than imaging findings, as structural healing on MRI does not always correlate with functional improvement [22, 41, 42].

Postoperative limitations in activity level cannot be explained solely by incomplete meniscal healing. Follow-up suggested that some patients voluntarily reduced activity intensity or avoided high-impact sports due to fear of re-injury, reflecting a form of protective psychological adaptation [43]. Similar psychological barriers have been widely reported, and psychological readiness has been consistently identified as a key determinant of successful return to sport, even in the presence of satisfactory functional recovery [41, 44]. In addition, postoperative rehabilitation is also critical for RTS. Higher motivation and adherence to rehabilitation have been associated with improved functional recovery [45, 46], which may partly account for the variability in postoperative activity levels in this study.

In the subgroup analysis, patients with preoperative BME who underwent PRP-augmented repair showed a tendency toward better functional recovery. This phenomenon may relate to the pathophysiological state reflected by BME and the biological mechanisms of PRP. One possible explanation is that BME reflects a state of increased subchondral stress and local inflammation, which may be more responsive to the biological effects of PRP, which is rich in multiple growth factors and anti-inflammatory cytokines and may suppress inflammatory responses, promote bone and cartilage repair, and improve the local microenvironment [11, 17, 47]. In contrast, repair alone may not directly address intraosseous inflammation or microstructural damage, which could explain why BME continued to adversely affect postoperative functional outcomes in the surgery-alone group. For patients with meniscal tears accompanied by BME, PRP-augmented repair may improve postoperative functional outcomes.

In summary, PRP augmentation was associated with improved early functional recovery, pain relief, RTS outcomes and meniscal healing following traumatic meniscal repair. However, its mid- to long-term effects gradually diminish over time. Several potential mechanisms may explain this phenomenon. First, the biological effects of PRP attenuate over time. During the early phase, PRP continuously releases growth factors and cytokines within the joint cavity for up to 7 days or more, which may contribute to early pain relief and enhanced healing [48]. Over time, growth factor release decreases, and the production of synovial fluid further dilutes their concentration, leading to diminished long-term promoting effects [21, 49]. Second, the long-term functional recovery may be influenced by multiple factors, such as the intrinsic meniscal healing potential, psychological factors, and rehabilitation motivation [41, 50, 51]. As postoperative intrinsic meniscal healing continued and rehabilitation progressed, patients undergoing isolated repair may achieve comparable mid to long-term functional outcomes. Third, earlier RTS in the PRP group may expose the meniscus to mechanical loading sooner, potentially inducing low-grade inflammation and thereby partially negating the initial benefits [52].

Overall, PRP may therefore be more appropriate for patients seeking faster early recovery or those presenting with concomitant BME, rather than as a determinant of long-term outcome.

Several limitations should be acknowledged. First, the retrospective design introduces inherent risks of selection bias and incomplete data, which could not be fully eliminated despite standardized inclusion criteria and fixed follow-up time points. Second, the relatively modest sample size may have limited the statistical power for certain secondary and subgroup analyses. Third, only a single intraoperative PRP injection protocol was evaluated, and variations in PRP composition, dosage, or administration strategy were not explored.

Future multicenter matched RCTs are required to further validate the efficacy of PRP in traumatic meniscal injury patients. Objective PRP parameters should be measured to identify the optimal therapeutic concentration. Additionally, standardized rehabilitation protocols and psychological assessment are needed to elucidate the influence of rehabilitation compliance and psychological readiness on patient prognosis.

Conclusions

PRP augmentation for traumatic meniscal repair may provide clinically improvements at 6 months postoperatively, including better IKDC score, Tegner scale, and VAS, a higher meniscal healing rate, and facilitate earlier RTS. However, these benefits diminished by 12 months, with functional differences falling below the MCID and no sustained difference in healing rate. Patients with preoperative BME may derive greater functional benefit from adjunctive PRP treatment.

Abbreviations

PRP

Platelet-rich plasma

IKDC

International knee documentation committee

VAS

Visual analogue scale

RTS

Return to sport

RTPL

Return to preinjury level

BME

Bone marrow edema

MCID

Minimal clinically important difference

Author contributions

LHF and TL conceived and designed the study. LHF, TL, YJZ and YZ developed the methodology. SQZ, ZPJ and JDS performed validation. TL, QG and ZPJ contributed to visualization. TL, YJZ and QG conducted the formal analysis. BCX and WLQ carried out the investigation. BCX, WLQ and HPZ provided resources. TL, YJZ and YZ curated the data. TL and YJZ drafted the original manuscript. All authors contributed to reviewing and editing the manuscript. LHF supervised the study and managed the project. All authors read and approved the final manuscript.

Funding

Not applicable.

Data availability

The datasets used and/or analysed during the current study are available from the corresponding author on reasonable request.

Declarations

Ethics approval and consent to participate

The study was approved by the institutional ethics committee of the Second Affiliated Hospital of Xi’an Jiaotong University (Approval No. 2025-237). Owing to the retrospective design and use of anonymized clinical data, the need for informed consent was waived by the ethics committee.

Consent for publication

Not applicable.

Competing interests

All authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.