Platelet-Rich Plasma Augmentation for Isolated Arthroscopic Meniscal Repairs Leads to Significantly Lower Failure Rates: A Systematic Review of Comparative Studies.

BACKGROUND: Studies have reported relatively high failure rates of isolated meniscal repairs. Platelet-rich plasma (PRP) has been suggested as a way to increase growth factors that enhance healing.
PURPOSE: To compare (1) meniscal repair failures and (2) patient-reported outcomes after isolated arthroscopic meniscal repair augmented with and without PRP. STUDY
DESIGN: Systematic review; Level of evidence, 3.
METHODS: A systematic review was performed using the PRISMA (Preferred Reporting Items for Systematic Meta-Analyses) guidelines. Multiple databases were searched for studies that compared outcomes of isolated arthroscopic meniscal repair augmented with PRP versus without PRP in human patients. Failures and patient-reported outcome scores were reported for each study and compared between groups. Study heterogeneity was assessed using I 2 for each outcome measure before meta-analysis. Study methodological quality was analyzed. Continuous variable data were reported as mean and standard deviation from the mean. Categorical variable data were reported as frequency with percentage. All P values were reported with significance set at P < .05.
RESULTS: Five articles were analyzed (274 patients [110 with PRP and 164 without PRP]; 65.8% male; mean age, 29.1 ± 4.6 years; mean follow-up, 29.2 ± 22.1 months). The risk of meniscal repair failure ranged from 4.4% to 26.7% for PRP-augmented repairs and 13.3% to 50.0% for repairs without PRP. Meniscal repairs augmented with PRP had significantly lower failure rates than repairs without PRP (odds ratio, 0.32; 95% CI, 0.12-0.90; P = .03). One of the 5 studies reported significantly higher outcomes in the PRP-augmented group versus the no-PRP group for the International Knee Documentation Committee (IKDC), Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), and Knee injury and Osteoarthritis Outcome Score (KOOS) (P < .05 for all). The remaining 4 studies reported no significant difference between groups with regard to outcomes for the IKDC, Lysholm knee scale, visual analog scale for pain, or Tegner activity level.
CONCLUSION: Although the studies were of mostly of low quality, isolated arthroscopic meniscal repairs augmented with PRP led to significantly lower failure rates (10.8% vs 27.0%; odds ratio, 0.32; P = .03) as compared with repairs without PRP. However, most studies reported no significant differences in patient-reported outcomes.

The meniscus functions to provide joint stability, congruency, proprioception, and force distribution across the knee.[33,34] Meniscal injuries are one of the most common conditions treated by orthopaedic surgeons, with up to 61% of patients demonstrating meniscal pathology on imaging.[9,15] Once the meniscus is injured, the loss of meniscal integrity leads to altered mechanics and joint forces with resultant increased contact pressures on the articular cartilage.[16,27,28,42] As such, meniscal preservation has been increasingly emphasized.[1] Biomechanical studies have demonstrated that meniscal repair restores the tibiofemoral contact pressures to similar levels to that of an intact meniscus while partial meniscectomy leads to significantly higher values.[2,3,29,39,42] Clinical studies have also found there to be significantly improved patient-reported outcomes and decreased progression to osteoarthritis but with relatively high failure rates after meniscal repair.[8,41,43,47,49]

Multiple risk factors for meniscal repair failure have been identified, including tobacco use, increasing age, location, and surgeon experience.[4,32] Additionally, some studies have suggested that concomitant anterior cruciate ligament (ACL) reconstruction may lead to improved meniscal healing and outcomes owing to increased bleeding within the joint.[5,10,30,32] As such, there have been several biologic augmentation techniques described for meniscal repairs, including fibrin clot, marrow stimulation, and platelet-rich plasma (PRP), with varying degrees of success.[25,40,44] PRP to augment soft tissue reconstruction procedures has been suggested as a way to increase growth factors that enhance healing in the absence of large hemarthrosis.[13,21,22,50] However, the studies involving PRP augmentation for arthroscopic meniscal repair are limited by small sample sizes and a lack of consensus.

The purpose of this study was to compare (1) meniscal repair failures and (2) patient-reported outcomes after isolated arthroscopic meniscal repair augmented with PRP versus without PRP. We hypothesized that there would be no significant differences in (1) meniscal repair failures or (2) patient-reported outcomes between groups.

Methods

This systematic review was registered with PROSPERO on January 27, 2020, and the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines were followed.[38] We conducted separate searches of the following medical databases: PubMed, SCOPUS, and Cochrane Central Register of Controlled Trials. The searches were performed on January 27, 2020, by a single orthopaedic surgery sports medicine fellow (K.R.S.) and was confirmed by the senior author (S.L.S.). The search terms used were “platelet-rich plasma” and “meniscus” (((((“platelet-rich plasma”[Medical Subject Headings (MeSH) Terms] OR (“platelet-rich”[All Fields] AND “plasma”[All Fields])) OR “platelet-rich plasma”[All Fields]) OR ((“platelet”[All Fields] AND “rich”[All Fields]) AND “plasma”[All Fields])) OR “platelet-rich plasma”[All Fields]) AND ((“meniscus”[MeSH Terms] OR “meniscus”[All Fields]) OR “menisci”[All Fields])).

Eligible studies consisted of evidence levels 1 to 3 (for therapeutic research per the Oxford Centre for Evidence-Based Medicine), were published in the English language, and compared the outcomes of isolated arthroscopic meniscal repair augmented with and without PRP in human patients. Animal studies, basic science studies, review articles, book chapters, and technique papers were excluded. In the event of different studies with duplicate or overlapping populations, the studies with the greatest number of participants or the greatest clarity of methods and results were included if the participants could not be separated. All references within the included studies were cross-referenced for inclusion if missed by the initial search. Duplicates were removed, and the remaining results were reviewed against inclusion criteria to determine the articles that were included in the final analysis (Figure 1).

Figure 1.

Flow diagram summarizing the literature search, screening, and review using the PRISMA (Preferred Reporting Items for Systematic Meta-Analyses) guidelines. PRP, platelet-rich plasma.

Data were extracted from the included studies using the methodology recommended by Harris et al.[19] All study, participant, and surgery parameters, including PRP type, were collected. Study and participant demographic parameters included year of publication, years of participant enrollment, number of participants, number of knees, laterality, age, sex, length of follow-up, meniscal tear location, meniscal tear type, surgical technique, and PRP preparation. Clinical outcomes recorded were meniscal repair failures and all knee-specific patient-reported outcome scores: International Knee Documentation Committee (IKDC), Lysholm knee scale, visual analog scale for pain, Tegner activity level, Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), and Knee injury and Osteoarthritis Outcome Score (KOOS). The primary outcome measure was the rate of meniscal repair failure. Failure was defined by postoperative physical examination, magnetic resonance imaging (MRI), and/or second-look arthroscopy.

The risk of study bias and methodological quality were analyzed using the Modified Coleman Methodology Score (MCMS), with scores reported as excellent (85 to 100), good (70 to 84), fair (55 to 69), and poor (<55).[6] Meniscal repair failures and patient-reported outcome scores were assessed for heterogeneity using I 2 for each outcome measure before meta-analysis. Outcomes with I 2 <40% were deemed to be adequately homogeneous for meta-analysis.[20] Where I 2 was >40% after pooling, no meta-analysis was performed. Forest plots were created using Review Manager (Version 5.3; Nordic Cochrane Centre, Cochrane Collaboration). Dichotomous data were reported as odds ratios (ORs) using a random-effects model, and continuous data were reported as mean differences and 95% CIs. Continuous variable data were reported as mean and standard deviations. Categorical variable data were reported as frequency with percentage. All P values were reported with significance set at <.05.

Results

A total of 178 articles were screened, and 5 articles were included in the final analysis (Table 1).[7,11,18,24,26] Four articles were level 3 evidence,[7,11,18,26] and 1 was level 1.[24] According to the MCMS, 1 study was excellent,[24] 1 was good, [26] 1 was fair, [7] and 2 were poor, [11,18] with a mean score of 67.0 ± 17.8.

Table 1

Summary of Study Characteristics

	Griffin (2015)[18]	Kemmochi (2018)[26]	Kaminski (2018)[24]	Dai (2019)[7]	Everhart (2019)[11]
Level of evidence	3	3	1	3	3
MCMS	49 (poor)	70 (good)	94 (excellent)	69 (fair)	53 (poor)
PRP preparation and use	PRP fibrin matrix sutured into meniscal repair site	Leukocyte-rich PRP fibrin clot inserted into meniscal repair site and PRP injected into knee	Thrombin-activated leukocyte-rich PRP clot injected into meniscal repair site	Thrombin-activated leukocyte-rich PRP clot injected into discoid lateral meniscal repair site	Thrombin-activated leukocyte-rich PRP clot injected into meniscal repair site
Sample size
PRP	15	17	19	14	45
No PRP	20	5	18	15	106
Laterality, L/R
PRP	6 L, 9 R	10 L, 7 R	NR	NR	NR
No PRP	11 L, 9 R	2 L, 3 R	NR	NR	NR
Meniscal tear location, M/L
PRP	8 M, 7 L	6 M, 13 L	16 M, 2 M + L, 1 L	14 L	NR
No PRP	6 M, 14 L	1 M, 4 L	11 M, 1 M + L, 6 L	15 L	NR
Meniscal tear type
PRP	6 bucket-handle, 2 horizontal, 7 longitudinal/vertical	NR	19 bucket-handle	NR	NR
No PRP	4 bucket-handle, 1 horizontal, 13 longitudinal/vertical, 2 undersurface	NR	18 bucket-handle	NR	NR
Meniscal repair technique
PRP	13 inside-out, 1 all-inside, 1 outside-in	17 all-inside + outside-in	9 all-inside, 10 all-inside + outside-in	14 inside-out	NR
No PRP	4 inside-out, 13 all-inside, 3 outside-in	5 all-inside + outside-in	13 all-inside, 5 all-inside + outside-in	15 inside-out	NR
Age, y
PRP	26	32	30	32	NR
No PRP	35	21	26	30	NR
Sex, M/F
PRP	11 M, 4 F	9 M, 8 F	15 M, 4 F	6 M, 8 F	NR
No PRP	17 M, 3 F	3 M, 2 F	15 M, 3 F	5 M, 10 F	NR
Follow up, mo	48	6	54	21	36
Outcomes	IKDC, Lysholm, ROM, return to sport, return to work, failure	IKDC, Lysholm, Tegner	IKDC,b VAS, KOOS,b WOMAC,b failureb	Lysholm, VAS, Ikeuchi grade, failure	Failureb

IKDC, International Knee Documentation Committee; KOOS, Knee injury and Osteoarthritis Outcome Score; L/R, left/right; MCMS, Modified Coleman Methodology Score; M/F, male/female; M/L, medial/lateral; NR, not reported; PRP, platelet-rich plasma; ROM, range of motion; VAS, visual analog scale for pain; WOMAC, Western Ontario and McMaster Universities Osteoarthritis Index.

Statistically significant difference between meniscal repair augmented with and without PRP (P < .05).

The number of patients per study ranged from 22 to 151, for a total of 274 patients and 274 knees: 110 augmented with PRP and 164 without PRP. Three studies included more men than women (65.8% men). The patient age in the studies ranged from 26.6 to 31.4 years (mean, 29.1 ± 4.6 years) with a follow-up ranging from 6.0 to 54 months (mean, 29.2 ± 22.1 months). There was no significant difference in demographics between the patients with and without PRP augmentation in all studies, except in 1 study in which the group without PRP was significantly older than the group with PRP (35.0 vs 26.0 years; P = .045).[18]

All patients were diagnosed with meniscal tears based on physical examination, MRI, and arthroscopy at the time of surgery (Table 1). Four studies[7,18,24,26] described the location of the meniscal tear, and 3 studies[7,18,24] reported the tear type. The majority of meniscal tears were located in the lateral meniscus (59.2%), followed by the medial meniscus (38.4%) and combined medial and lateral menisci (2.4%). The most common meniscal tear morphologies were bucket-handle (46.5%), longitudinal/vertical (30.7%), horizontal (9.9%), complex (9.9%), undersurface (2.0%), and radial (1.0%). Four studies[7,18,24,26] described the meniscal repair technique. The most common techniques for meniscal repair were inside-out (37.4%), all-inside combined with outside-in (30.1%), all-inside (29.3%), and outside-in (3.3%).

Four studies[7,11,24,26] utilized leukocyte-rich PRP, with 1 study[18] not specifying leukocyte-rich versus leukocyte-poor formulations. Two studies utilized PRP with a fibrin matrix[18] or clot[26] that was inserted into the repair site. The remaining studies injected thrombin-activated leukocyte-rich PRP into the meniscal repair site.[7,11,24] All participants, regardless of PRP augmentation, underwent similar and standardized meniscal preparation, including debridement and/or rasping of the repair site. No marrow stimulation was utilized in either group.

The IKDC[18,24,26] and Lysholm knee scale[7,18,26] were the most frequently used outcome scores (3 of 5 studies each). The visual analog scale[7,24] was used in 2 studies. Tegner activity level,[26] WOMAC,[24] and KOOS[24] were used in 1 study each. Four studies recorded failure rates after meniscal repair (Table 2).[7,11,18,24]

Table 2

Outcome Measures by Study

	Griffin (2015)[18]	Kemmochi (2018)[26]	Kaminski (2018)[24]	Dai (2019)[7]	Everhart (2019)[11]
IKDC
PRP	69 ± 26	87.4 ± 10.4	97.56 ± 0.63b	NR	NR
No PRP	76 ± 17	91.5 ± 1.2	84.77 ± 0.92	NR	NR
Lysholm
PRP	66 ± 31.9	95.8 ± 7.1	NR	79.8 ± 9.6	NR
No PRP	89 ± 9.7	97.2 ± 1.8	NR	74.6 ± 11.6	NR
VAS
PRP	NR	NR	0.84 ± 0.1	1.2 ± 1.0	NR
No PRP	NR	NR	0.89 ± 0.08	1.6 ± 1.1	NR
Tegner
PRP	NR	5.9 ± 2.3	NR	NR	NR
No PRP	NR	7.8 ± 1.6	NR	NR	NR
KOOS
PRP	NR	NR	Pain: 96.06 ± 0.23b Symptoms: 96.23 ± 0.31b ADL: 98.18 ± 0.13b Sport: 89.44 ± 0.86b QOL: 80.90 ± 1.09b	NR	NR
No PRP	NR	NR	Pain: 92.86 ± 0.43 Symptoms: 92.33 ± 0.48 ADL: 95.14 ± 0.38 Sport: 77.65 ± 1.26 QOL: 66.18 ± 1.17	NR	NR
WOMAC
PRP	NR	NR	0.95 ± 0.13b	NR	NR
No PRP	NR	NR	3.95 ± 0.33	NR	NR
Ikeuchi grade
PRP	NR	NR	NR	10 (71.4) excellent or good	NR
No PRP	NR	NR	NR	12 (80.0) excellent or good	NR
Failure
PRP	4 (26.7)	NR	3 (15.8)b	1 (7.1)	2 (4.4)b
No PRP	5 (25.0)	NR	9 (50.0)	2 (13.3)	27 (25.4)

Values are presented as mean ± SD or No. (%). ADL, Activities of Daily Living; IKDC, International Knee Documentation Committee; KOOS, Knee injury and Osteoarthritis Outcome Score; NR, not reported; PRP, platelet-rich plasma; QOL, Quality of Life; VAS, visual analog scale for pain; WOMAC, Western Ontario and McMaster Universities Osteoarthritis Index.

Statistically significant difference between meniscal repair augmented with and without PRP (P < .05).

Meniscal repair failure was defined by Dai et al[7] as the recurrence of meniscal symptoms or requirement of repeat arthroscopy. Two studies considered repair failure if patients developed meniscal symptoms and required reoperation, including meniscectomy, revision meniscal repair, or knee arthroplasty.[11,18] Kaminski et al[24] defined failure per MRI or second-look arthroscopy. Kemmochi et al[26] did not evaluate failure, and their study was not included in the meta-analysis.

Two studies reported that meniscal repair with PRP augmentation led to significantly lower failure rates as compared with meniscal repairs without PRP (P = .002 and P = .048).[11,24] The remaining 2 studies found no significant difference in failure rates between groups.[7,18] The risk of meniscal repair failure ranged from 4.4% to 26.7% for PRP-augmented repairs and 13.3% to 50.0% for repairs without PRP. Meta-analysis showed that meniscal repairs augmented with PRP had significantly lower failure rates than repairs without PRP (10.8% vs 27.0%; OR, 0.32; 95% CI, 0.12-0.90; P = .03) (Table 2, Figure 2).

Figure 2.

Forest plot of failure differences between meniscal repairs augmented with and without PRP. Failure was defined by postoperative physical examination, magnetic resonance imaging, and/or second-look arthroscopy. M-H, Mantel-Haenszel; PRP, platelet-rich plasma.

One study reported significantly higher outcome scores in the PRP-augmented group as compared with the no-PRP group: IKDC (P = .001), WOMAC (P = .002), and KOOS (P < .05 for all subscales).[24] Note that the 1 study[24] demonstrating the difference in outcomes was the randomized controlled trial, which had the longest follow-up and the second-most patients. All other studies (4 of 5) reported no significant difference between groups with regard to IKDC, Lysholm, visual analog scale, or Tegner scores (Table 2, Figure 3).

Figure 3.

Forest plots of mean outcome differences between meniscal repairs augmented with and without PRP for the International Knee Documentation Committee grade and Lysholm. IV, inverse variance; PRP, platelet-rich plasma.

Discussion

It was determined that there are conflicting results in the literature regarding patients undergoing isolated arthroscopic meniscal repair augmented with PRP as compared with no PRP. Meta-analysis of failure rates demonstrated that meniscal repairs augmented with PRP result in significantly lower failure rates than do repairs without PRP. However, only 1 study reported significantly improved patient-reported outcomes (although this was the only level 1 study in this meta-analysis and it had the longest follow-up), with the remaining studies finding no significant differences between groups.

The rate of isolated meniscal repair failure has been reported to range from 0.0% to 30.0% in recent literature, with a cumulative failure rate of 23.1%.[17,41] This is similar to the studies in the current review, with reported failures rates ranging from 13.3% to 50.0% and a resultant pooled failure rate of 27.0% in patients without PRP. Those patients with PRP augmentation, however, had a significantly reduced pooled failure rate of 10.8% (OR, 0.32; P = .03) for isolated meniscal repairs.

This finding may be explained by the upregulation of growth factors with resultant increased viability of meniscal cells from PRP that has been shown in vivo.[13,21,22,50] However, all PRP formulations are not equal. The concentration of platelets in PRP can range from 200,000 to >1 million platelets per microliter, with varying numbers of leukocytes and growth factors.[12,36] Additionally, PRP formulations differ by the presence of fibrin architecture and/or need for an activating agent such as calcium or thrombin.[12,36] In the present work, 2 studies utilized PRP with a fibrin matrix[18] or clot[26] that was inserted into the repair site. The remaining studies injected thrombin-activated leukocyte-rich PRP clots into the meniscal repair site.[7,11,24] Although all PRP formulations were present at the conclusion of the procedure, we were unable to reliably determine the duration of time that PRP remains at the repair site before dissolution. These different formulations and uses likely contribute to the varying results in the literature regarding patient outcomes and failure rates. However, this has not been adequately studied, and the relationship between PRP formulations and outcomes could not be determined in the present analysis.

The majority of the studies included in this review utilized a PRP clot (fibrin or thrombin activated) that was injected into meniscal repair sites. Previous studies have investigated meniscal repair augmentation with a fibrin clot prepared from venous blood as opposed to PRP. The failure rates from venous fibrin clot augmentation has ranged from 15% to 50% in isolated meniscal repairs.[23,40,44] This is similar to the failure rates in the present study without PRP augmentation (13.3%-50.0%) and higher than in meniscal repairs with PRP (4.4%-26.7%). As such, venous fibrin clot appears to be inferior to PRP augmentation and may add little value as an augmentation to meniscal repair as compared with repairs without biologic reinforcement. However, this should be investigated in future comparative studies.

It is also important to note that this study examined the effect of PRP in isolated meniscal repairs. Previous studies have demonstrated no benefit to PRP for meniscal repair healing in patients undergoing concomitant ACL reconstruction.[10,11,32] This is thought to be secondary to increased bleeding in the joint from ACL tunnel drilling, leading to elevated growth factors.[5,14,51] Marrow stimulation techniques within the notch have thus been used as an adjunct to healing in isolated meniscal repair.[25] However, there are currently no data comparing marrow stimulation against PRP. Based on prior studies, PRP augmentation should presently be considered only in patients undergoing isolated meniscal repairs.

In the current study, the majority of meniscal tears were located in the lateral meniscus (59.2%), with 39.1% of these occurring in discoid menisci. This is a unique pathology that had a high recurrent tear rate of 59% and resultant progression to symptomatic osteoarthritis in a large proportion of patients at 8-year follow up.[45] Dai et al[7] investigated PRP augmentation in these patients at almost 2 years postoperatively and found there to be a 7.1% failure rate versus 13.3% for no PRP. As such, PRP augmentation for discoid lateral meniscal repairs may lead to improved healing rates, comparable with those of the normal lateral meniscus.

Medial meniscal tears accounted for 38.4% of all meniscal tears in the present study. This location is particularly challenging to obtain healing, as the medial meniscus has been shown to be an independent risk factor for meniscal repair failures as compared with the lateral meniscus.[32] Despite this inherent disadvantage, PRP augmentation resulted in reduced failure rates versus controls. It is therefore possible that by augmenting with PRP, one may be able to improve the healing rates of medial meniscal tears.

Additionally, the meniscal tear morphology differed among patients and studies. The majority of tears were bucket-handle (46.5%) and longitudinal (26.7%), with horizontal (9.9%), complex (9.9%), vertical (4.0%), undersurface (2.0%), and radial (1.0%) tears making up a lesser proportion of meniscal tear patterns. No study demonstrated a significant difference in healing rates among meniscal tear morphology. This is not entirely unexpected, as previous studies have shown there to be equivalent healing rates independent of tear patterns.[32,37,48] The same trend appears to hold true even with PRP augmentation. There was also no significant difference in failures based on the repair technique in any study included in the review. The most common techniques for meniscal repair were inside-out (37.4%), all-inside combined with outside-in (30.1%), and all-inside (29.3%). This supports previous clinical and biomechanical studies without PRP that showed there to be equivalent outcomes regardless of repair technique.[31,35,41,46]

Despite the improved failure rate of meniscal repairs augmented with PRP, 1 study reported significantly higher patient-reported outcome scores as compared with no PRP. However, this was the only study included in the review that had significantly reduced failure rates and also recorded patient-reported outcomes. This was also the only evidence level 1 study; it had the longest follow up and second-largest study population; and it involved bucket-handle meniscal tears. The remaining studies that recorded patient-reported outcomes scores demonstrated no significant difference in failure rates, so it is not unexpected that there would be no difference in subjective patient outcome scores. This finding may be due to these studies being underpowered, with no formal power analysis in any study. Unfortunately, a meta-analysis was unable to be performed owing to study heterogeneity, with I [2] > 90% for all outcome scores. This limited the ability of the current work to determine if improved failure rates translate to improved patient-reported outcome scores after PRP augmentation of meniscal repairs. Future studies should provide standardization of their patient-reported outcome measurements, using the IKDC and Lysholm scores if possible.

There are limitations noted among the studies included in this review. The current design resulted in analysis of relatively few studies (5 studies) with a limited number of patients (274 patients) and with 1 study not included in the meta-analysis of failure rates. All of the articles were of evidence level 1 or 3. The level of evidence of the studies included in this review limits the strength of the conclusions. The mean methodological quality of the reviewed studies was fair, as assessed by the MCMS. Heterogeneity prevented a meta-analysis of the patient-reported outcome scores and is a significant limitation. Additionally, there was heterogeneity with regard to laterality (medial or lateral), tear morphology, and repair technique used. The definition of failure also varied among studies, with true failure rate probably underreported when relying solely on examination. However, failure rate was sufficiently homogeneous and able to be synthesized using I [2]. In future studies, failure should be standardized and defined by the need for repeat knee arthroscopy and subsequent meniscectomy or revision repair. These limitations reflect the underlying limitations of the literature on this topic, with only 1 randomized study. Future studies should thus be performed in a randomized fashion with more homogeneous meniscal tear types, repair techniques, and follow-up assessments of repair healing at standardized time points.

Additionally, clinical relevance using the minimal clinically important difference and/or Patient Acceptable Symptom State was unable to be obtained. It is an individual-level measure and may not be translatable to group-level statistics. No study reported individual-level data for patient-reported outcomes. Given the lack of patient-level outcomes, the impact of meniscal tear location, morphology, or repair technique was unable to be obtained. Additionally, the type, preparation, and application of PRP varied among the studies. Future studies should report on the characteristics of their PRP. Another possible limitation of this review is that we may have overlooked other relevant studies on this topic, despite conducting a systematic search.

In conclusion, although the studies were of mostly low quality, isolated arthroscopic meniscal repairs augmented with PRP led to significantly lower failure rates (10.8% vs 27.0%; OR, 0.32; P = .03) when compared with repairs without PRP. However, most studies reported no significant differences in patient-reported outcome scores.