Use of Adjunctive Platelet-Rich Plasma for Healing During Arthroscopic Release and Repair for Recalcitrant Lateral Epicondylitis: A Prospective,Double-Blind,Randomized Controlled Trial

Abstract

Background:

Whether the use of platelet-rich plasma (PRP) as an adjuvant to extensor carpi radialis brevis (ECRB) repair in recalcitrant lateral epicondylitis (RLE) promotes tendon healing and improves clinical outcomes remains unclear.

Purpose:

To evaluate the tendon healing and clinical outcomes of arthroscopic ECRB repair combined with PRP injection and compared with arthroscopic ECRB repair alone at early-term follow-up in patients with RLE.

Study Design:

Randomized controlled trial; Level of evidence, 1.

Methods:

A consecutive series of 80 patients with RLE were enrolled and randomized to the PRP group (arthroscopic ECRB repair followed by 1 PRP injection; n = 40) and the control group (arthroscopic ECRB repair alone; n = 40). Magnetic resonance imaging was performed to assess tendon healing at 3, 6, and 12 months. The visual analog scale (VAS) for pain, the Mayo Elbow Performance Score (MEPS), the Disabilities of the Arm, Shoulder and Hand (DASH) questionnaire, the Patient-Rated Tennis Elbow Evaluation (PRTEE) scale, range of motion, and muscle strength were evaluated at preoperative and follow-up points. The time to return to work was also compared between the 2 groups. Patients and assessors were blinded to the intervention.

Results:

A total of 80 patients who met the inclusion criteria were enrolled between July 2020 and July 2023, and 73 patients completed follow-up. The PRP group contained 35 patients, 11 men and 24 women, with a mean age of 47.8 ± 8.8 years. The control group contained 38 patients, 13 men and 25 women, with a mean age of 44.5 ± 5.8 years. No significant differences were found in magnetic resonance imaging classification and functional scores between groups at preoperative and follow-up periods. VAS, MEPS, DASH, and PRTEE scores and muscle strength showed significant improvement at 12 months in both groups (P < .001). However, the PRP group showed a significant improvement in grip and wrist extension muscle strength at 6 weeks postoperatively (P = .008 and P < .001, respectively), whereas the control group did not (P = .583 and .056). No complications were associated with PRP injection.

Conclusion:

PRP used as an adjuvant to ECRB repair did not show a difference in tendon healing and functional outcomes compared with ECRB repair alone for RLE at 12-month follow-up. However, PRP treatment showed a difference in muscle strength at 6-week follow-up compared with ECRB repair alone.

Registration:

NCT04556825 (ClinicalTrials.gov).

Keywords

recalcitrant lateral epicondylitis arthroscopic platelet-rich plasma (PRP)ECRB tendon repair

Lateral epicondylitis (LE) of the elbow is a common tendinopathy, mainly involving the extensor carpi radialis brevis (ECRB), with a reported incidence of 1% to 3%.²² Although nonoperative treatment is the first-line treatment for most patients, surgery is required for patients with long duration of the condition and poor nonsurgical response, which has been defined as recalcitrant LE (RLE) (5%-10%).^9,32

Among the current surgical methods for RLE, using either open or arthroscopic approaches, repair of the ECRB may provide better recovery of function and muscle strength compared with ECRB debridement alone.^13,14,26,35 In addition, arthroscopic intervention for RLE may avoid unnecessary surgical trauma and allow cotreatment of intra-articular lesions, resulting in good clinical outcomes.^1,8,27,34 However, despite recent advances in surgical techniques for ECRB tendon repair for LE, some studies have reported persistent postoperative pain, poor functional improvement, and weak muscle strength.^{13,14,21,26,35,37} The reason for poor clinical outcomes may be nonhealing or poor healing of the tendon-to-bone interface of the ECRB, even when repaired to the anatomic footprint, which is similar to rotator cuff tears and anterior cruciate ligament injuries.^2,5,6 In addition, the injured ECRB does not regain its original histological features after repair, which probably results in reduced biomechanical strength.^{15,28,35,38,44}

Platelet-rich plasma (PRP) is a plasma rich in platelets and various growth factors that is extracted and concentrated from the patient’s blood. Theoretically, PRP promotes tendon healing by releasing a variety of growth factors, including platelet derived growth factor (PDGF), transforming growth factor-β (TGF-β), vascular endothelial growth factor (VEGF), and insulin-like growth factor-1 (IGF-1).^17,23 Among these, PDGF can regulate chemotaxis, angiogenesis, fibroblast mitosis, and macrophage activation; TGF-β can stimulate fibroblast and macrophage recruitment, cell proliferation, and collagen production; and IGF-1 can stimulate fibroblast proliferation and migration, collagen gene expression, and protein synthesis.^10,17,23,46 Therefore, PRP has been widely used as a nonoperative treatment for various tendinopathies such as those affecting the rotator cuff, lateral epicondyle, Achilles tendon, patellar tendon, and gluteal tendon, with modest improvements.^12,16,28,29 In addition, PRP has been used in conjunction with tendon repair to accelerate tendon-to-bone healing, improve clinical outcomes, and reduce the retear rate, such as in rotator cuff tears and meniscal tears.^2,6,42 Previous studies have shown that PRP injection improves clinical outcomes in nonoperative treatment of LE.^33,36,40 However, the difference between arthroscopy and nonoperative management is that some surgeons may release the ECRBs from their origin and completely debride the affected tissue before repairing the normal tendon. No studies have been conducted regarding the effectiveness of arthroscopically repaired ECRB combined with PRP injections in the treatment of RLE and whether clinical outcomes and healing rates are improved compared with ECRB repair alone. Therefore, whether PRP injection is an effective adjunct to arthroscopic ECRB repair to promote tendon healing is worthy of further investigation.

The purpose of this study was to evaluate the tendon healing and clinical outcomes of arthroscopic ECRB repair combined with PRP injection and compare the short-term outcomes with those of RLE patients who received arthroscopic ECRB repair alone. Our hypothesis was that arthroscopic ECRB repair combined with PRP injections would be effective in healing the tendon, reducing pain, and improving functional and strength recovery in patients with RLE and would provide better clinical outcomes compared with ECRB repair alone at short-term follow-up.

Methods

Study Design

This study was a prospective, double-blinded, randomized controlled trial that was performed at a single shoulder and elbow center. The study was approved by ethics committee of our institution (Ethics Review No. 202005-12) and registered with ClinicalTrials.gov (NCT04556825). All patients provided oral and written consent to participate in this investigation.

Participants

Between July 2020 and July 2023, there were 201 consecutive patients with persistent RLE, of whom 80 met the inclusion criteria to be enrolled in the study.

Inclusion criteria for the study were as follows: (1) patients aged 20 to 60 years; (2) patients with RLE who had experienced failure of at least 6 months of nonoperative treatment, including rest, nonsteroidal anti-inflammatory drugs, cryotherapy, antiforce brace protection, and physical therapy; (3) no steroid injections within 3 months before surgery and no previous PRP injections or previous surgery; (4) no other complications or medical status preventing surgery; (5) unilateral injury; and (6) voluntary participation in clinical follow-up.

Exclusion criteria were as follows: (1) patients who did not receive nonoperative treatment; (2) patients who underwent invasive procedures such as steroid injection or acupuncture within 3 months before surgery; (3) patients who had received previous PRP injections; (4) patients with elbow joint instability; (5) patients with poor local skin condition and local infection; and (6) patients with autoimmune diseases, elbow deformities, central nervous system damage, severe cognitive dysfunction, and other diseases.

Randomization and Blinding

A computer-generated 1:1 open randomized list was prepared by one of the authors (X.L.) who was not involved in patient recruitment. The numbered, opaque, and sealed envelopes were used sequentially to contain the randomized results. After consent, patients were randomized into 2 groups (PRP group and control group) based on the envelope. Both patients and evaluators were blinded to treatment. The surgeon learned of a given patient’s group only after the tendon repair was completed, when the operating nurse informed the surgeon whether to inject the patient with PRP, according to the grouping in the envelope.

Surgical Procedure

All surgeries were performed by 1 experienced surgeon (Y.L.). Patients were placed in the lateral decubitus position on the operating table, and the affected elbow was flexed at 90°. Five arthroscopic portals were created: soft spot, accessory posterolateral, proximal anteromedial, proximal anterolateral, and anterolateral portals. The radial-capitellar joint was examined initially through the soft spot portal. Plica removal was performed by shaver through the accessory posterolateral portal. The ECRB lesion was then evaluated by arthroscopy through the proximal anteromedial portal. The ECRB tendon was identified, released, and debrided with radiofrequency and shaver through the proximal anterolateral portal. Finally, a 3.5-mm suture anchor (Healicoil; Smith & Nephew) was inserted through the anterolateral portal, and the torn tendon was repaired by the anchor threads passed through the tendon in modified Mason-Allen way and then tied subcutaneously, as reported in previous literature.²⁶

In the PRP group, after ECRB repair, a leukocyte-poor PRP (LP-PRP) extractor (Regen ACR-C; Regen Lab SA) was used to collect 10 mL of autologous blood, which was centrifuged (3500 rpm, 1500g, 9 minutes) to obtain 4 mL of LP-PRP. After the closure of all portals except the proximal anteromedial portal, the needle of the PRP injector was inserted into the ECRB tendon-bone interface under the guidance of arthroscopic supervision and maintained in position (Figure 1). While an assistant held the syringe steady, the pump was switched off, the intra-articular fluid was aspirated, and the proximal anteromedial portal was closed. The PRP injection was then performed.

Postoperative Rehabilitation

All patients followed the same rehabilitation program. A plaster cast was used 1 week postoperatively for protection. Active range of motion (ROM) exercises for the shoulder and digits began on the first day postoperatively. When the plaster cast was removed, elbow passive ROM exercises began. Active assisted ROM exercises were allowed 3 weeks after surgery. Patients were encouraged to use their arms for daily activities and slowly progress to more difficult tasks and were allowed to return to work at 6 weeks, as reported in previous literature.²⁶

Data Collection

Patients’ age, sex, involved side, dominant side, body mass index (BMI), working status, duration of symptoms, and number of previous steroid injections were collected. Working status was classified as moderate daily work, office work, and heavy labor.

Magnetic resonance imaging (MRI) was performed preoperatively and at 3, 6, and 12 months postoperatively to evaluate tendon healing. Patients who underwent MRI were classified into 4 grades: grade 0, normal signal at the ECRB site; grade 1, focal increased signal without tendon thickness; grade 2, increased signal involving ≤50% of the tendon cross section with thickness; grade 3, increased signal involving >50% of the tendon cross section with thickness.⁴¹ All MRI scans were initially evaluated by 2 evaluators (S.L. and R.C.) and further assessed by a senior physician (L.Y.) in case of any discrepancy. All were blinded to the grouping situation.

Pain during activities of daily living was assessed preoperatively, at 3 and 6 weeks postoperatively, and at 3, 6, and 12 months postoperatively using a 0- to 10-point visual analog scale (VAS). ROM, including flexion-extension and pronation-supination, was assessed preoperatively, at 3 and 6 weeks postoperatively, and at 3, 6, and 12 months postoperatively. Functional assessments included strength measurements and functional scores, obtained preoperatively, at 3 and 6 weeks postoperatively, and at 3, 6, and 12 months postoperatively. Strength measurements included grip and wrist extensor strength. Grip strength was measured with a Camry electronic force gauge, and wrist extension strength was measured with a Mark-10 electronic force gauge. Three measurements were taken and averaged. Bilateral strength was measured and the result calculated as (Affected Side × 100%)/Healthy Side, eliminating individual differences. Functional measures included the Mayo Elbow Performance Score (MEPS), the Disabilities of the Arm, Shoulder and Hand (DASH) questionnaire, and the Patient-Rated Tennis Elbow Evaluation (PRTEE) scale.

During the postoperative follow-up, patients were asked to report the time points at which they performed activities of daily living without assistance, returned to work, and fully returned to normal life.

Sample Size Analysis

According to the results of the pilot study, all data were normally distributed with equal variance. The improvement in MEPS results after surgery was 20 ± 6.1 in the PRP group and 14 ± 7.1 in the non-PRP group, with a mixed standard deviation of 7.0 and a significance level of α = .05 and β = .10. A postoperative improvement in MEPS >5 points in the PRP group compared with the non-PRP group was used as the gold standard for treatment effectiveness.^7,31 The sample size was estimated to be 32 patients in each group.

Statistical Analysis

IBM SPSS for Windows, Version 24.0, was used for all statistical analyses. Nonparametric tests and t tests were used to compare continuous variables, and the chi-square test or Fisher test was used for categorical variables. The mean ± standard deviation or median (interquartile range, IQR) value was used for descriptive statistical measures. Pain scores, functional assessment scores, ROM, muscle strength, and physical examination were compared between 2 groups at the same time points and within groups preoperatively and postoperatively. The statistical significance of the difference was considered as P < .05.

Results

A total of 80 patients who met the inclusion criteria were enrolled between July 2020 and July 2023. Of these, 73 patients completed follow-up and 7 patients were lost to follow-up, including 5 in the PRP group and 2 in the control group (Figure 2).

Patient Demographics

In total, 73 patients were included and analyzed with 12 months of follow-up. The PRP group contained 35 patients, 11 men and 24 women, with a mean age of 47.8 ± 8.8 years. Among them, 24 patients (68.6%) were dominant-hand involved. The mean BMI for the PRP group was 24.4 ± 4.1. The control group contained 38 patients, 13 men and 25 women, with a mean age of 44.5 ± 5.8 years. Among them, 30 patients (78.9%) were dominant-hand involved. The mean BMI was 25.2 ± 6.1. No significant differences were observed in the baseline parameters between the 2 groups. Details are presented in Table 1.

Table 1

Baseline Characteristics ^a

	PRP Group(n = 35)	Control Group(n = 38)
Age, y	47.8 ± 8.8	44.5 ± 5.8
Sex, male/female, n	11/24	13/25
Involved arm, right, n	22	25
Dominant arm, affected, n	24	30
Body mass index, kg/m²	24.4 ± 4.1	25.2 ± 6.1
Working status, moderate daily work/office work/heavy labor, n	9/19/7	7/20/11
Duration of symptoms, mo	17.0 ± 12.3	16.3 ± 10.2
No. of previous steroid injections, median (interquartile range)	2 (0-3)	2 (0-3)

Data are expressed as mean SD unless otherwise noted. PRP, platelet-rich plasma.

MRI Assessment of Tendon Characteristics

MRI results at preoperative assessment and postoperative follow-up are shown in Table 2. No significant differences were observed between the 2 groups at each follow-up.

Table 2

Results of Magnetic Resonance Imaging Evaluation ^a

	Grade	PRP Group, n	Control Group, n	P
Preoperative	0	0	0	.952
	1	7	8
	2	16	16
	3	12	14
3-mo follow-up	0	21	25	.609
	1	14	13
	2	0	0
	3	0	0
6-mo follow-up	0	28	32	.639
	1	7	6
	2	0	0
	3	0	0
12-mo follow-up	0	34	38	.294
	1	1	0
	2	0	0
	3	0	0

PRP, platelet-rich plasma.

Clinical Assessment

VAS Score

The median (IQR) VAS scores were 7 (5-8) in the PRP group and 6 (4.75-7) in the control group preoperatively, with no statistically significant differences. No statistically significant differences between the 2 groups were found at any follow-up time. Both groups showed a statistically significant improvement starting from 3 weeks postoperatively compared with preoperatively (Table 3).

Table 3

Comparison Between Preoperative and Postoperative Scores and Measurements ^a

	PRP Group		Control Group
	Value	P ^b	Value	P ^b	P ^c
VAS
Preoperative	7 (5-8)		6 (4.75-7)		.069
3 wk	5 (3-6)	.001	5 (3-5.25)	<.001	.330
6 wk	3 (2-5)	<.001	3 (2.75-5)	<.001	.866
3 mo	2 (1-3)	<.001	2 (1-3)	<.001	.844
6 mo	1 (0-3)	<.001	1 (0-2)	<.001	.708
12 mo	00 (0-0)	<.001	00 (0-0)	<.001	.351
Range of flexion-extension, deg
Preoperative	135 (135-135)		135 (135-135)		.143
3 wk	125 (110-135)	.016	125 (115-135)	.034	.421
6 wk	135 (135-135)	.208	135 (135-135)	.123	.136
3 mo	135 (135-135)	.307	135 (135-135)	.127	.422
6 mo	135 (135-135)	.624	135 (135-135)	.715	.258
12 mo	135 (135-135)	.916	135 (135-135)	.463	.919
Range of pronation-supination, deg
Preoperative	150 (150-150)		150 (150-150)		.988
3 wk	150 (150-150)	.326	150 (150-150)	.478	.312
6 wk	150 (150-150)	.511	150 (150-150)	.686	.730
3 mo	150 (150-150)	.417	150 (150-150)	.526	.364
6 mo	150 (150-150)	.629	150 (150-150)	.365	.849
12 mo	150 (150-150)	.701	150 (150-150)	.912	.955
MEPS
Preoperative	70 (55-80)		70 (55-72.5)		.671
3 wk	70 (60-85)	.500	70 (63.75-85)	.069	.330
6 wk	85 (70-85)	.003	85 (70-85)	<.001	.868
3 mo	85 (85-85)	<.001	85 (85-85)	<.001	.655
6 mo	100 (85-100)	<.001	92.5 (85-100)	<.001	.699
12 mo	100 (100-100)	<.001	100 (96.25-100)	<.001	.059
DASH
Preoperative	44.2 (28.5-70.3)		44.6 (26.9-59.4)		.497
3 wk	54.5 (46.7-71.7)	.016	54.6 (46.3-66.0)	.003	.749
6 wk	45.3 (26.7-58.3)	.306	46.5 (33.1-51.8)	.954	.921
3 mo	16.6 (10.0-33.9)	<.001	23.5 (14.0-36.4)	<.001	.302
6 mo	6.7 (0.0-23.3)	<.001	7.1 (0.0-14.5)	<.001	.858
12 mo	0.0 (0.0-2.0)	<.001	0.0 (0.0-6.8)	<.001	.155
PRTEE
Preoperative	50.0 (38.0-59.0)		45.5 (35.25-54.75)		.299
3 wk	44.5 (40.0-54.0)	.330	47.25 (36.125-63.0)	.380	.829
6 wk	37.5 (27.0-46.5)	.004	37.5 (24.875-46.875)	.049	.952
3 mo	16.0 (9.0-31.0)	<.001	23.25 (10.375-33.375)	<.001	.235
6 mo	6.0 (2.0-20.5)	<.001	5.0 (0.0-16.35)	<.001	.459
12 mo	0.0 (0.0-2.0)	<.001	0.0 (0.0-6.0)	<.001	.305
Grip strength, %
Preoperative	66.0 (35.6-80.9)		63.3 (42.1-91.3)		.691
3 wk	58.5 (46.0-78.6)	.706	61.8 (39.9-74.1)	.455	.639
6 wk	75.0 (59.4-88.0)	.008	67.1 (80.4-53.7)	.587	.231
3 mo	83.5 (75.9-97.1)	<.001	82.9 (71.0-98.1)	.014	.544
6 mo	95.5 (75.8-103.4)	<.001	94.0 (78.9-100.0)	<.001	.581
12 mo	101.9 (96.9-104.8)	<.001	103.2 (97.3-107.1)	<.001	.973
Wrist extension muscle strength, %
Preoperative	57.7 (39.6-82.4)		58.1 (32.4-76.6)		.724
3 wk	60.6 (47.6-76.6)	.376	49.3 (37.3-71.6)	.464	.227
6 wk	71.7 (59.8-90.1)	<.001	63.3 (51.8-80.2)	.056	.126
3 mo	88.8 (72.4-99.6)	<.001	80.2 (61.3-96.6)	.001	.129
6 mo	93.3 (79.3-101.9)	<.001	96.1 (72.4-101.1)	<.001	.635
12 mo	100.0 (95.1-106.5)	<.001	98.7 (91.6-103.2)	<.001	.243

Data are expressed as median (interquartile range). DASH, Disabilities of the Arm, Shoulder and Hand; deg, degree; MEPS, Mayo Elbow Performance Score; PRP, platelet-rich plasma; PRTEE, Patient-Rated Tennis Elbow Evaluation; VAS, visual analog scale for pain.

Compared with preoperative.

Between groups.

ROM

The median (IQR) range of flexion-extension was 135 (135-135)° in the PRP group and 135 (135-135)° in the control group preoperatively, with no statistically significant differences. No statistically significant differences were found between the 2 groups at 3 and 6 weeks and 3, 6, and 12 months.

The median range of pronation-supination was 150 (150-150)° in the PRP group and 150 (150-150)° in the control group preoperatively, with no statistically significant differences. No statistically significant differences were noted between the 2 groups at 3 and 6 weeks and 3, 6, and 12 months (Table 3).

Functional Score

In the PRP group, the median (IQR) MEPS was 70 (55-80), 70 (60-85), 85 (70-85), 85 (85-85), 100 (85-100), and 100 (100-100) at preoperative assessment and 3-week, 6-week, 3-month, 6-month, and 12-month postoperative follow-up assessments, respectively. In the control group, the median MEPS was 70 (55-72.5), 70 (63.75-85), 85 (70-85), 85 (85-85), 100 (85-100), and 100 (96.25-100) at the respective assessments.

In the PRP group, the median DASH score was 44.2 (28.5-70.3), 54.5 (46.7-71.7), 45.3 (26.7-58.3), 16.6 (10.0-33.9), 6.7 (0.0-23.3), and 0.0 (0.0-2.0) at preoperative assessment and 3-week, 6-week, 3-month, 6-month, and 12-month postoperative follow-up, respectively. In the control group, the median DASH score was 44.6 (26.9-59.4), 54.6 (46.3-66.0), 46.5 (33.1-51.8), 23.5 (14.0-36.4), 7.1 (0.0-14.5), and 0.0 (0.0-6.8) respective assessments.

In the PRP group, the median PRTEE score was 50.0 (38.0-59.0), 44.5 (40.0-54.0), 37.5 (27.0-46.5), 16.0 (9.0-31.0), 6.0 (2.0-20.5), and 0.0 (0.0-2.0) at preoperative assessment and 3-week, 6-week, 3-month, 6-month, and 12-month postoperative follow-up, respectively. In the control group, the median PRTEE score was45.5 (35.25-54.75), 47.25 (36.125-63.0), 37.5 (24.875-46.875), 23.25 (10.375-33.375), 5.0 (0.0-16.35), and 0.0 (0.0-6.0) at respective assessments.

No statistically significant differences were found between the 2 groups in any of the functional scores at any follow-up time (Table 3).

Muscle Strength

The median (IQR) preoperative grip strength percentage was 66.0% (35.6%-80.9%) in the PRP group and 63.3% (42.1%-91.3%) in the control group, with no statistically significant differences between 2 groups. No statistically significant differences were seen between the 2 groups at 3 weeks, 6 weeks, and 3, 6, and 12 months. In the PRP group, a statistically significant improvement was noted starting from 6 weeks postoperatively compared with preoperatively. In the control group, a statistically significant improvement was seen starting from 3 months postoperatively compared with preoperatively.

The median preoperative wrist extension muscle strength percentage was 57.7% (39.6%-82.4%) in the PRP group and 58.1% (32.4%-76.6%) in the control group, with no statistically significant differences. Similarly, in the PRP group, there was a statistically significant improvement starting from 6 weeks postoperatively compared with preoperatively. In the control group, we noted a statistically significant improvement starting from 3 months postoperatively compared with preoperatively (Table 3).

Return to Work

The median (IQR) time of return to work was 8 weeks (6-13 weeks) for the PRP group and 8 weeks (6.5-13 weeks) for the control group, with no significant difference between the 2 groups (P = .567). Subgroup analysis according to labor types showed no significant difference between groups and no significant difference between different labor types (Table 4).

Table 4

Subgroup Analysis of Comparison of Time to Return to Work ^a

	PRP Group	Control Group	P
Moderate daily work	9 (8-14)	9 (6-13)	.999
Office work	8 (6-13)	11 (7-13)	.552
Heavy labor	7 (6-17)	7 (6-12.5)	.783
P	.349	.477

Data are expressed in weeks as median (interquartile range). PRP, platelet-rich plasma.

Complications

Consistent pain occurred after surgery in 2 patients (1 in each group). One temporary radial paralysis in the control group and recovered 3 months postoperatively. No other complications were noted. No significant difference was found in the rate of complications between the 2 groups (2.9% vs 5.3%; P ≥ .999).

Discussion

The main finding of the present study was that PRP used as an adjuvant to ECRB repair did not show a difference in tendon healing and functional outcomes compared with ECRB repair alone for RLE at 12-month follow-up. Patients treated with PRP showed a difference in muscle strength at 6-week follow-up compared with those with ECRB repair alone, but this difference disappeared over time. In addition, PRP injection as an adjuvant intraoperative procedure was a safe procedure with no associated complications.

The present study showed that arthroscopic ECRB repair combined with PRP injection provided satisfactory results for patients with RLE. In previous studies, ECRB debridement was the preferred surgical treatment for RLE, and the majority of patients had good results. In 1979, Nirschl and Pettrone³² reported that ECRB debridement provided a 97.7% improvement rate. However, only 85% of patients were able to return to their previous activities. Furthermore, several studies using open or arthroscopic debridement of ECRB for RLE showed less effective pain relief and less favorable recovery of function and muscle strength.^{3,18,20,34,39} In 2005, Thornton et al⁴³ showed that ECRB repair with suture anchor for LE achieved full recovery of grip and pinch strength in an open procedure. In 2009, Pruzansky et al³⁵ showed that ECRB reattachment to bone for chronic LE allowed all patients to return to their preinjury level of function. Compared with debridement alone, ECRB repair was found to accelerate patients’ recovery of function and strength. In addition, arthroscopic treatment of LE can simultaneously treat intra-articular lesions, avoid damage to the extensor carpi radialis longus (ECRL), and reduce patient recovery time.^11,27 In 2000, Baker et al³ described arthroscopic debridement for LE with functional improvement. Arthroscopic treatment has since become a good option for the treatment of RLE. In 2021, Li et al²⁶ showed that arthroscopic ECRB repair for LE provided better functional scores than arthroscopic ECRB debridement alone. Both of the arthroscopic ECRB repair groups in the current study showed similar postoperative benefits in pain relief, function, and muscle strength recovery compared with previous studies.

This study is the first to show that arthroscopic ECRB repair provides satisfactory tendon healing from 3 months postoperatively, as assessed using MRI. Approximately 60% to 65% of patients showed no further MRI abnormalities in the ECRB at 3 months, 80% to 84% at 6 months, and almost 100% at 12 months, suggesting progressive healing of the ECRB from at least 3 months postoperatively. Such findings are consistent with pain relief and recovery of function and muscle strength reported by patients and the theoretical basis of tendon-bone healing.^19,45

Theoretically, PRP leads to tendon healing at the repair site by releasing growth factors such as tumor necrosis factor α, PDGF, TGF-β, VEGF, and IGF-1, which contribute to the inflammatory process as well as remodeling of the extracellular matrix and stimulating the proliferation of tendon cells.^10,17,23,46 PRP is now widely used as a nonoperative treatment for a variety of tendinopathies, including LE, with modest improvements. Mishra et al³⁰ showed less tenderness in patients with RLE treated with PRP (29%) compared with a control group (54%) at 24 weeks. Kivrak and Ulusoy²⁴ showed a more effective result with PRP than steroid injections in long-term follow-up. Krogh et al²⁵ showed that PRP injection alone led to faster short-term pain relief and better postoperative functional scores compared with saline injection. Although ECRB repair combined with PRP injection has not been reported for the treatment of RLE, surgical treatment combined with PRP injection has been reported for rotator cuff tears and meniscal tears.^2,4,6,23,46 Barber et al⁴ showed lower retear rates (30% vs 60%) and better Rowe scores (94.9 vs 84.8) after rotator cuff repair in a PRP group compared with a control group, respectively. However, Castricini et al⁶ reported that the use of PRP did not augment rotator cuff repair. Theoretically, ECRB repair combined with PRP injections for RLE should accelerate tendon-to-bone healing, improve function and muscle strength, and reduce retear rates. However, there is no consensus in the literature on the effect of PRP on the tendon healing and anatomic integrity after ECRB repair, and no similar literature has been reported. The present study, which is the first to our knowledge to investigate ECRB repair combined with PRP injections for the treatment of RLE, showed safe and satisfactory short-term results.

The present study showed a significant improvement in muscle strength at 6 weeks postoperatively compared with baseline. However, although both groups had a significant improvement in strength from 3 months to 12 months postoperatively compared with baseline, the control group did not show a similar improvement at 6 weeks postoperatively. Therefore, PRP injections might play a role in tendon healing at an early point after ECRB repair. We believe the possible reasons are as follows. First, when PRP injections were used in combination with ECRB repair to treat RLE, the ECRB repair have already provided adequate results for tendon healing, so that the PRP injections did not have sufficient effects on functional improvement and just influenced muscle strength only in the early stages. Second, PRP injections provide a short-term release of growth factors for tendon healing and do not have a long-term effect. Therefore, further studies are needed to investigate this potential effect. In addition, the study showed a complication rate of only 2.9% (1/35) in the PRP group and 5.3% (2/38) in the control group. Previous studies have reported persistent pain after PRP injection.^10,25,31 However, the present study demonstrated that pain levels were the same with or without PRP injections, without any additional pain triggers.

The limitations of this study are as follows. First, the sample size was relatively small for further subgroup analysis, but our power was adequate; in addition, this study was a randomized controlled trial, and the main objective was to determine whether PRP as an adjuvant could promote postoperative tendon-to-bone healing. Second, clinical efficacy was assessed at 12 months postoperatively, which is a short time period, but the time period assessed in previous studies of PRP and surgery for LE has ranged from 6 to 12 months. Third, different PRPs may not have the same effect; we used LP-PRP in our study strictly according to surgical standards and minimized the effect of leukocytes in PRP on pain.

Conclusion

PRP used as an adjuvant to ECRB repair did not show a difference in tendon healing and functional outcomes compared with ECRB repair alone for RLE at 12-month follow-up. However, patients treated with PRP showed a difference in muscle strength at 6-week follow-up compared with those with ECRB repair alone.

Footnotes

Submitted October 11, 2024; accepted April 7, 2025.

One or more of the authors has declared the following potential conflict of interest or source of funding: Funding was received from Beijing Natural Science Foundation L222013. AOSSM checks author disclosures against the Open Payments Database (OPD). AOSSM has not conducted an independent investigation on the OPD.

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