Although plica syndrome is usually asymptomatic, it can manifest as a secondary condition due to inflammation [1]. The knee is divided into suprapatellar, medial, and lateral compartments by the plica, which is the remaining part of embryonic development [2,3]. After 16 gestational weeks, the synovial membrane is thought to be absorbed, creating a single joint cavity. According to another theory, a cavity forms when the distance between the proximal tibia and distal femur widens, which occurs around week 7 of pregnancy [4].

The most commonly observed area during knee arthroscopy is the infrapatellar plica [5]. The infrapatellar plica is the region that is most frequently observed during knee arthroscopy. When a plica is hypertrophic, it loses its elasticity and develops ossification, calcification, and fibrosis [6].

A variation in the prevalence of plica syndrome can be observed. Arthroscopic studies have shown that the incidence rates of suprapatellar, infrapatellar, medial patellar, and lateral patellar plica are 87%, 86%, 72%, and 1.3%, respectively. Moreover, patients who are active with repetitive knee movements are more likely to develop symptomatic plica [7].

Plica syndrome may cause a dull pain in the anteromedial area of the knee, which may be worsened by physical exercise. It may be related to clicking sounds, joint locking, and a sensation of knee instability; however, it is unrelated to swelling or joint effusion [8,9].

The initial treatment consists of analgesics, anti-inflammatory drugs, and reducing activities that strain the knee. Conservative treatments including hamstring, gastrocnemius stretching, and cryotherapy are recommended. Surgery may be indicated if nonsurgical treatments are not successful for over 6 months. The successful removal of the medial plica has been shown through arthroscopy [6].

However, case studies on the use of Korean medicine for plica syndrome have been limited, most of which mainly focused on cases related to traffic accidents [10]. This case study aims to investigate patients experiencing knee pain associated with plica syndrome and provides insights gained from applying acupuncture and pharmacopuncture. This case study is the first to assess the effectiveness of acupuncture and pharmacopuncture in treating knee pain associated with plica syndrome.

1. Treatment methods

1) Acupuncture

Disposable sterilized stainless steel acupuncture needles (0.25 × 30 mm; Dongbang Medical Co.) were used for 15 minutes. Acupuncture was performed on the affected knee that penetrated EX-LE4, EX-LE5, ST36, and GB36 twice daily.

2) Pharmacopuncture

Pharmacopuncture (Shinbaro 2; Jaseng Wonoe Tangjunwon) was performed using a 1 mL insulin syringe with a disposable 29-gauge × 13 mm needle (1 mL twice daily; total, 2 mL). The needle was inserted to a depth of 1 cm (0.5 mL dosage per acupoint) at EX-LE4 and EX-LE5 and the trigger point of the anterior knee area (1 mL) (Table 1).

Table 1 . Pharmacotherapy administered to the patients.

Pharmacopuncture prescription	Herbal medicine components (g/mL)	Daily dose
SJ3-SBO Shinbaro 2	Paeonia lactiflora (0.0027) Ostericum koreanum (Max) Kitagawa (0.0013) Aralia continentalis (0.0013) Cortex Eucommiae (0.0013) Achyranthis Radix (0.0013) Rhizoma Cibotii (0.0013) Radix Ledebouriellae (0.0013) Acanthopanacis Cortex (0.0013) Scolopendra subspinipes mutilans (0.0013)	4 vials (1 mL/vial)

3) Herbal medicine

Gyeosuhwalhyeoljitung-tang (Case 1) and Mabalgwanjeol-tang (Case 2) were both prescribed three times a day. The herbal components given to both patients were prepared at the Jaseng Hospital of Korean Medicine and placed in pouches (75 mL/pouch). Table 2 shows the herbal components, daily doses, and schedule.

Table 2 . Korean traditional medicine herbal prescriptions administered to the patients.

Herbal prescription	Herbal medicine components	Administered	Daily dose
Gyeosuhwalhyeoljitung-tang (Case 1)	Lonicerae Flos (8 g) Akebiae Caulis (8 g) Coicis Semen (8 g) Atractylodis Rhizoma (8 g) Cinnamomi Ramulus (4 g) Dianthi Herba (4 g) Angelicae Gigantis Radix (4 g) Persicae Semen (4 g) Saposhnikoviae Radix (4 g) Angelicae Dahuricae Radix (4 g) Rehmanniae Radix Crudus (4 g) Linderae Radix (4 g) Achyranthis Radix (4 g) Clematidis Radix (4 g) Hoelen (4 g) Paeoniae Radix (4 g) Citri Unshii Pericarpium (4 g) Cnidii Rhizoma (4 g) Gentianae Scabrae Radix (4 g) Polygoni Avicularis Herba (4 g) Caesalpiniae Lignum (2 g) Carthami Flos (2 g)	Day 1–21	Extract of 100 mL, 3×/d
Mabalgwanjeol-tang (Case 2)	Lasiosphaera Seu Calvatia (12 g) Ginseng Radix (8 g) Achyranthis Radix (8 g) Glycyrrhizae Radix (4 g) Hordei Fructus Germinatus (4 g) Osterici Radix (4 g) Plastrum testudinis (4 g) Saposhnikoviae Radix (4 g) Amomi Fructus (4 g) Astragali Radix (4 g) Angelicae Pubescentis Radix (4 g) Aconiti tuber (2.8 g)	Day 2–29	Extract of 100 mL, 3×/d

4) Medicinal steaming therapy

Medicinal steaming therapy was performed daily. Gyeosuhwalhyeoljitung-tang, which is used for musculoskeletal diseases, was steamed in an herbal pouch and applied to the affected knee joint for 30 minutes (Table 3).

Table 3 . Herbal medicine prescriptions for deep fascia meridian therapy.

Prescription	Herbal medicine components (g/pack)	Administered	Area
Deep fascia meridian therapy	Rhei Rhizoma (50 g) Asiasari Radix (50 g) Angelica dahurica (50 g) Salviae miltiorrhizae Radix (50 g) Ledebouriellae Radix (40 g) Carthami Flos (30 g) Paeoniae Radix Rubra (30 g) Angelica gigas (25 g) Aconiti Lateralis Preparata Radix (20 g) Saussureae Radix (15 g)	Once a day	Knee

2. Assessments

1) Patient reported scales

Overall pain was measured daily using the numerical rating scale (NRS) [11]. The knee joint functional disability was assessed using the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) [12]. Moreover, the patient’s quality of life was assessed using the EuroQol 5-Dimension 5-Level (EQ-5D) [13].

2) Range of motion and special provocative test

The range of motion (ROM), including lateral bending, flexion, and extension of the knee joint, was measured. Special stress tests, including the stress valgus and stress varus tests, were performed (Tables 4, 5).

Table 4 . ROM and special provocative tests (Case 1).

	ROM												Special test
	Flexion (°)			Extension			The lat. bending Rt.			The lat. bending Lt.			Stress varus			Stress valgus
	Rt.	Lt.		Rt.	Lt.		Rt.	Lt.		Rt.	Lt.		Rt.	Lt.		Rt.	Lt.
December 11, 2023	135	135		0	0		5	5		5	5		(-)	(-)		(-)	(-)
December 18, 2023	135	135		0	0		5	5		5	5		(-)	(-)		(-)	(-)
December 23, 2023	135	135		0	0		5	5		5	5		(-)	(-)		(-)	(-)

ROM, range of motion; lat., lateral; Rt., right; Lt., left..

Table 5 . ROM and special provocative tests (Case 2).

	ROM												Special test
	Flexion (°)			Extension			The lat. bending Rt.			The lat. bending Lt.			Stress varus			Stress valgus
	Rt.	Lt.		Rt.	Lt.		Rt.	Lt.		Rt.	Lt.		Rt.	Lt.		Rt.	Lt.
June 24, 2024	90	90		0	0		5	5		5	5		(-)	(+)		(-)	(+)
July 8, 2024	135	135		0	0		5	5		5	5		(-)	(-)		(-)	(-)
July 22, 2024	135	135		0	0		5	5		5	5		(-)	(-)		(-)	(-)

ROM, range of motion; lat., lateral; Rt., right; Lt., left..

3. Case 1

1) Patient

A 41-year-old female patient.

2) Principal complaints

Left knee anterior pain.

3) Onset

On August 15, 2023.

4) Diagnosis

On November 14, 2023, the patient underwent an X-ray of both knees, which indicated no significant findings. However, the left knee magnetic resonance imaging (MRI), performed on December 11, 2023, revealed infrapatellar plica syndrome without any other joint diseases (Fig. 1).

Figure 1. Case 1: Left knee magnetic resonance imaging (December 11, 2023).

5) Medical history

A 41-year-old female patient experienced anterior knee pain in August 2023, with no history of trauma, and presented with tenderness in the anterior region and pain upon flexion beyond 90°. The pain continued even after taking painkillers. Therefore, she visited the Jaseng Hospital of Korean Medicine for outpatient treatment on November 14, 2023. She was admitted on December 11, 2023, and was discharged on December 23, 2023.

6) Progress notes

On admission, the patient reported anterior left knee pain and was able to walk independently. The MRI findings confirmed plica syndrome, with NRS and WOMAC scores of 7 and 38 points, respectively. The ROM was 135° for flexion and 0° for extension.

Ten days later, the NRS score decreased to 5. On discharge, the WOMAC score decreased to 15, with the pain score improving from 7 to 5, the functional score from 26 to 10, and the stiffness score from 4 to 2 (Fig. 2). Pain during flexion and extension was improved, and the nighttime pain resolved. Moreover, the EQ-5D score improved from 0.445 at admission to 0.817 at discharge (Fig. 3). The MRI findings confirmed plica syndrome, with NRS and WOMAC scores of 7 and 38 points, respectively. The ROM was 135° for flexion and 0° for extension (Table 4).

Figure 2. Case 1: Changes in the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) scores.

Figure 3. Case 1: Changes in the EuroQol 5-Dimension 5-Level (EQ-5D) scores for left knee pain.

4. Case 2

1) Patient

A 65-year-old male patient.

2) Principal complaints

Knee pain in both knees.

3) Onset

On June 1, 2024.

4) Diagnosis

On June 24, 2024, the X-rays of both knees revealed mild degenerative changes. However, the left knee MRI performed on June 25, 2024, revealed deep infrapatellar bursitis and infrapatellar plica syndrome. The patient was diagnosed with infrapatellar plica syndrome, and an medial collateral ligament issue was also identified (Fig. 4).

Figure 4. Case 2: Left knee magnetic resonance imaging (June 25, 2024).

5) Medical history

On admission (June 24, 2024), the patient reported bilateral knee pain with significant discomfort with no history of trauma. Prolonged standing worsened the pain, which was accompanied by a warm sensation on the inner side of the left knee. The NRS and WOMAC scores of the left knee were 7 and 56 points, respectively, with the ROM for flexion and extension being 90° and 0°, respectively. Meanwhile, the stress test results were negative (Table 5).

6) Progress notes

On admission, the WOMAC score was 56 points. Fifteen days later, the left knee pain decreased, with the NRS and WOMAC scores decreasing to 4 and 36 points, respectively. On discharge (July 22, 2024), the WOMAC score slightly increased to 44 points, with the pain score decreasing from 7 to 5, the functional score from 26 to 10, and the stiffness score from 4 to 2 (Fig. 5). The pain during left knee flexion and extension improved, and the nighttime pain resolved. The EQ-5D score improved from 0.606 on admission to 0.718 on Day 15 and 0.730 on discharge (Fig. 6).

Figure 5. Case 2: Changes in the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) scores.

Figure 6. Case 2: Changes in EuroQol 5-Dimension 5-Level (EQ-5D) for left knee pain.

Plica syndrome is a condition in which the synovial membrane within the knee joint thickens or becomes inflamed, resulting in dysfunction and pain. It is mainly caused by repetitive knee use or trauma, with characteristic symptoms including anterior knee pain, feelings of swelling, and clicking sounds. Its conventional standard treatments include physical therapy, injection therapy, and nonsteroidal anti-inflammatory drugs. In certain cases, synovial resection through arthroscopy may be required. Recently, various nonsurgical treatment options such as shockwave therapy and platelet-rich plasma therapy have been widely implemented.

Although research on Korean medicine for knee disorders is ongoing, studies specifically targeting plica syndrome remain limited. The primary goals of Korean medicine treatments are to decrease inflammation, alleviate pain, and facilitate tissue regeneration. In this study, acupuncture, Shinbaro pharmacopuncture, and herbal medicine were applied, focusing on managing inflammation and restoring knee function. Acupuncture is effective in managing pain by activating opioid receptors, leading to the improvement of pain [14,15]. Pharmacopuncture involves the injection of herbal medicine into certain acupoints, providing rapid anti-inflammatory and pharmacological effects [16,17]. Although Shinbaro pharmacopuncture is known to exhibit anti-inflammatory effects for spinal stenosis in animal models, such effects have not yet been demonstrated for knee joints [18].

In this study, two patients with plica syndrome experienced significant pain relief and functional improvement through integrated Korean medicine treatment. Both patients showed significant improvement in their NRS scores, suggesting that the combined use of acupuncture, pharmacopuncture, and herbal medicine effectively reduced inflammation and promoted tissue recovery. Current treatments primarily focus on reducing pain, but integrated Korean medicine offers the potential to not only relieve pain but also enhance knee function, thereby preventing the condition from recurring in the long term.

However, this case study is limited by the lack of a control group, making it difficult to confirm the effectiveness of the treatment. Furthermore, follow-up imaging, such as MRI or ultrasound, was not performed to objectively assess the posttreatment changes in inflammation and structural recovery. To better evaluate the safety and effectiveness of integrated Korean medicine treatment, randomized controlled trials are necessary.

Plica syndrome may lead to chronic pain and functional impairment over time, but current treatments mainly focus on temporary pain relief. In particular, the repeated use of steroid injections in the long term can lead to tissue damage. In contrast, the use of integrated Korean medicine can be effective in managing chronic pain and dysfunction caused by plica syndrome, presenting a potential alternative treatment for long term management. Nevertheless, it is challenging to separate the effects of individual treatments, and the lack of a control group is considered a limitation. Therefore, further studies involving a broader range of Korean medicine treatments and follow-ups are needed to confirm the effectiveness of integrated Korean medicine in treating plica syndrome.

Conceptualization: GBL, JSK. Data curation: HWC, DYK. Formal analysis: GBL, DJK. Investigation: GBL, DJY. Methodology: YRY, JSY. Project administration: GBL, IJC. Resources: JSK, HWC. Software: DYK, DJK. Supervision: DJY, YRY. Validation: GBL. Visualization: GBL. Writing – original draft: GBL. Writing – review & editing: All authors.

The authors have no conflicts of interest to declare.

None.

The patients’ medical records were retrospectively obtained and approved for use by the Institutional Review Board (IRB) of Jaseng Hospital of Korean Medicine (IRB no. 2024-08-006).