This was a prospective, three-arm, parallel-group, assessor-blinded randomized controlled trial conducted at the Department of Rehabilitation Medicine, Gaoming District People’s Hospital of Foshan. The protocol was designed in accordance with the SPIRIT statement and CONSORT guidelines. The study was approved by the Ethics Committee of Gaoming District People’s Hospital of Foshan and conducted in accordance with the Declaration of Helsinki. Written informed consent was obtained from all participants. The trial was prospectively registered in the Chinese Clinical Trial Registry.

2.2.1. Diagnostic Criteria

KOA was diagnosed according to the Chinese Orthopaedic Association guidelines (2018 edition) [2]: (1) recurrent knee pain within the past month; plus at least one of: (2) radiographic evidence of joint space narrowing, subchondral bone sclerosis, cystic changes, or osteophyte formation; (3) age ≥ 50 years; (4) morning stiffness ≤ 30 minutes; (5) crepitus on active joint movement. Radiographic severity was classified using the Kellgren-Lawrence (K-L) grading system.

2.2.2. Inclusion and Exclusion Criteria

Inclusion criteria: (1) met the KOA diagnostic criteria; (2) age 50 - 70 years; (3) K-L grade II or III; (4) no pharmacological or physical therapy for KOA within one month prior to enrollment.

Exclusion criteria: (1) prior knee surgery; (2) knee pain secondary to fracture, infection, tumor, rheumatoid arthritis, or gout; (3) severe joint destruction with ligament or capsular deficiency; (4) obvious deformity or neurovascular disease of the affected limb; (5) severe hepatic, renal, cardiovascular, or psychiatric disorders; (6) known allergy to study medications; (7) poor anticipated compliance.

Eligible participants were randomly assigned (1:1:1) to FSN, SH, or MLX groups. Randomization sequence was generated using SPSS 26.0 (IBM Corp.) by an independent statistician. Allocation was concealed in sealed opaque envelopes. Outcome assessors and data analysts were blinded. Treating clinicians were not blinded but were not involved in outcome assessment. All assessments and treatments were conducted in separate rooms.

2.4.1. FSN Group

Participants received treatment 3 times/week (every other day) for 2 weeks (6 sessions). Disposable FSN needles (medium size; Nanjing Paifu Medical Technology Co., Ltd., Nanjing, China) were used. The clinician identified pathological muscles (tense or rigid) in the thigh compartments, tibialis anterior, popliteus, and peroneal muscles. The needling point was selected ~4 cm distal to the pathological muscle. After iodophor disinfection, the needle was inserted subcutaneously. A fan-shaped sweeping manipulation (~200 movements over ~2 min) was performed while the patient executed resisted active movement of the target muscle (~10 s contraction followed by relaxation). Key resisted movements included: knee extension (quadriceps), hip flexion (sartorius), hip adduction (medial thigh), knee flexion (biceps femoris and popliteus), and foot dorsiflexion (tibialis anterior). The soft cannula remained in place for 5 hours.

2.4.2. SH Group

Participants received one intra-articular injection of 25 mg sodium hyaluronate (Hyalgan®; Fidia Farmaceutici S.p.A., Italy) per week for 5 consecutive weeks, administered via the lateral patellofemoral approach.

2.4.3. MLX Group

Participants received 7.5 mg oral meloxicam (Mobic®; Boehringer Ingelheim, Germany) once daily after breakfast for 2 weeks. Gastric protection (omeprazole 20 mg once daily) was provided at the discretion of the treating physician for participants with risk factors for gastrointestinal adverse events; the number of participants receiving gastric protection was recorded. Rescue analgesics (oral acetaminophen up to 2 g/day) were permitted in all three groups, with dose and frequency documented at each assessment visit. Any use of exercise therapy, physiotherapy, or other co-interventions directed at the knee during the treatment and follow-up periods was prohibited and was monitored via patient diaries. No participant in any group received additional co-interventions during the study period.

All outcomes were assessed at baseline (T0), Week 1 (T1), post-treatment (T2), and Month 3 (T3). As the treatment durations differed across groups (FSN and MLX: 2 weeks; SH: 5 weeks), “post-treatment” refers to Week 2 for the FSN and MLX groups and Week 5 for the SH group. Despite this difference in absolute calendar timing, the post-treatment time point was defined prospectively as the primary comparison time point because it captures each intervention at the completion of its full intended course, thereby reflecting the maximal treatment effect specific to each modality and enabling a clinically meaningful direct between-group comparison.

2.5.1. Primary Outcomes

Pain intensity was measured using the Visual Analog Scale (VAS, 0 - 10). Osteoarthritis severity was assessed using the WOMAC index (0 - 96, higher = worse).

2.5.2. Secondary Outcomes

Knee function was evaluated using the Lysholm Knee Scoring Scale (0 - 100, higher = better). Range of motion (ROM) was assessed with a goniometer. Quality of life was assessed using the SF-12 Physical Component Summary (PCS, 0 - 100).

2.5.3. Inflammatory Markers

Venous blood samples were collected at each time point. Serum CRP was measured by immunoturbidimetry (Beckman Coulter AU5800). IL-1 and TNF-α were measured using commercial ELISA kits (R&D Systems, Minneapolis, MN, USA).

With α = 0.05, power = 0.80, and anticipated effect size of 0.5 for VAS, the minimum required sample was 30 per group. Accounting for a 25% dropout rate, 40 participants per group were enrolled (N = 120).

Statistical analyses were performed using SPSS 22.0. Continuous variables are presented as mean ± SD. The primary analysis was conducted on a modified intention-to-treat (mITT) population. For the two coprimary outcomes (VAS pain and WOMAC index) assessed at four time points, the significance level was adjusted using Bonferroni correction to control the family-wise error rate (adjusted α = 0.05/8 = 0.00625 for primary comparisons at post-treatment). Group comparisons at each time point used one-way ANOVA with Tukey’s HSD post-hoc test. Secondary outcomes were compared without further multiplicity adjustment and are considered exploratory. Pearson correlation coefficients examined associations between changes in inflammatory markers and clinical outcomes. All tests were two-tailed.

All personnel underwent standardized training. Treatment was performed by certified clinicians with >3 years of FSN experience. Outcome assessments were conducted by trained evaluators blinded to group allocation.

Of 156 patients screened, 120 met inclusion criteria and were randomized: 40 per group. The primary analysis was conducted on a modified intention-to-treat (mITT) basis, defined as all randomized participants who received at least one dose of the assigned intervention and provided at least one post-baseline assessment. All 120 participants met these criteria and were included in the mITT analysis. All 120 completed the study with no dropouts. Adherence to the assigned intervention was 100% (40/40) in the FSN group (all 6 sessions completed), 100% (40/40) in the SH group (all 5 injections received), and 95% (38/40) in the MLX group (at least 12 of 14 daily doses taken). Baseline characteristics were well balanced across groups (Table 1). Mean age was 61.8 ± 5.9 years, and 71.7% were female.

Table 1. Baseline demographic and clinical characteristics.

Note: Values are mean ± SD or n (%). FSN, Fu’s Subcutaneous Needling; SH, sodium hyaluronate; MLX, meloxicam; BMI, body mass index; K-L, Kellgren-Lawrence.

3.2.1. Pain (VAS)

All three groups showed significant reductions in VAS from baseline to post-treatment (all p < 0.001; Table 2). At post-treatment, the FSN group achieved significantly lower VAS (1.5 ± 1.6) compared with both SH (3.2 ± 1.9; p < 0.001) and MLX (3.0 ± 1.7; p < 0.001). At Month 3, FSN maintained significantly lower VAS (1.9 ± 2.0) versus SH (4.0 ± 1.9; p < 0.001) and MLX (4.3 ± 1.9; p < 0.001). The MLX group showed a pronounced rebound after treatment cessation.

3.2.2. WOMAC Index

WOMAC scores improved significantly in all groups (Table 2). At post-treatment, FSN showed significantly lower WOMAC (20.7 ± 13.3) versus SH (30.9 ± 15.4; p = 0.002) and MLX (37.8 ± 11.2; p < 0.001). At Month 3, FSN maintained improvement (24.3 ± 15.5), while MLX approached baseline levels (40.8 ± 15.4; p < 0.001 vs. FSN).

Table 2.Clinical outcomes by group and time point.

Note: Values are mean ± SD.

Lysholm scores improved most substantially in the FSN group (Table 2). At post-treatment, FSN achieved 72.6 ± 9.3, significantly higher than SH (69.4 ± 10.8; p = 0.048) and MLX (64.8 ± 10.8; p < 0.001). At Month 3, FSN remained at 72.1 ± 12.7 versus 66.7 ± 10.8 (SH) and 62.0 ± 12.4 (MLX).

Knee ROM improved from 96.7˚ ± 9.2˚ to 111.5˚ ± 10.6˚ at post-treatment in FSN (mean increase: +14.8˚), significantly exceeding MLX (99.8˚ ± 12.2˚; p < 0.001). At Month 3, FSN maintained 108.7˚ ± 11.4˚ versus 96.9° ± 11.4° in MLX (p < 0.001).

SF-12 PCS improved most in FSN, rising from 38.7 ± 10.0 to 51.2 ± 12.3 at post-treatment. While MLX showed comparable early improvement at Week 1 (43.4 ± 9.6), it declined to 38.1 ± 10.1 by Month 3, near baseline. FSN remained at 51.0 ± 11.3 (p < 0.001 vs. MLX).

Baseline serum levels of CRP, IL-1, and TNF-α were comparable across groups (Table 3, Figure 1). FSN exhibited significant and sustained reductions in all three markers. In contrast, MLX showed only transient suppression with rebound to near-baseline by Month 3.

Table 3. Inflammatory marker levels by group and time point.

Note: Values are mean ± SD.

Figure 1.Serum inflammatory marker levels over time. (A) C-reactive protein (CRP), (B) Interleukin-1 (IL-1), (C) Tumor necrosis factor-alpha (TNF-α). (D) Pearson correlation heatmap between changes in inflammatory markers (Δ, baseline to post-treatment) and changes in clinical outcomes. Data are presented as mean ± SD.

At post-treatment, CRP decreased by 45.1% in FSN (12.2 to 6.7 mg/L), compared with 32.2% in SH and 14.6% in MLX. IL-1 decreased by 36.1% in FSN versus 25.4% in SH and 15.1% in MLX. TNF-α decreased by 38.5% in FSN versus 20.1% in SH and 15.5% in MLX. At Month 3, FSN-maintained CRP reduction of 33.6%, compared with 14.0% in SH and 9.2% in MLX. IL-1 reduction was 36.1% in FSN versus 22.2% in SH and 4.7% in MLX. TNF-α reduction was 33.0% in FSN versus 15.9% in SH and 8.6% in MLX.

Pearson correlation analysis (Table 4) revealed significant correlations between changes in inflammatory markers and clinical outcomes from baseline to post-treatment. The strongest correlations were between ΔTNF-α and ΔVAS (r = 0.49, p < 0.001) and between ΔCRP and ΔWOMAC (r = 0.41, p < 0.001).

Table 4. Pearson correlations between changes in inflammatory markers and clinical outcomes (Baseline to Post-treatment).

Note: Δ denotes change from baseline to post-treatment. **p < 0.05; *p < 0.001.

No serious adverse events were reported. In the FSN group, minor adverse events included transient local ecchymosis (n = 5, 12.5%) and mild subcutaneous hematoma (n = 3, 7.5%), all resolving spontaneously. In the SH group, transient post-injection pain (n = 6, 15.0%) and mild joint swelling (n = 2, 5.0%) were reported. In the MLX group, gastrointestinal discomfort occurred in 8 participants (20.0%). No participant withdrew due to adverse events.

This randomized controlled trial provides robust evidence that FSN is superior to both SH injection and oral MLX for treating KOA across multiple clinically meaningful domains over a 3-month period. FSN produced greater reductions in pain and WOMAC scores, greater improvements in knee function, joint mobility, and quality of life, with sustained benefits beyond the active treatment period. Importantly, FSN was associated with significant and sustained reductions in CRP, IL-1, and TNF-α. These cytokine changes were correlated with clinical improvements, suggesting an association between systemic inflammatory marker suppression and therapeutic response.

The magnitude of pain relief with FSN (VAS reduction of 4.8 points, 76.2% improvement at post-treatment) substantially exceeds the minimal clinically important difference (MCID) of 2.0 points for VAS in KOA [22]. At Month 3, FSN-maintained pain relief (VAS: 1.9) remained robust, whereas MLX showed regression (VAS: 4.3), highlighting the transient nature of COX-2 inhibition.

WOMAC results reinforce FSN’s superiority. At Month 3, the FSN group maintained a 47.6% reduction from baseline, versus 25.1% for SH and 16.7% for MLX. This pattern was consistent across Lysholm, ROM, and SF-12 outcomes, demonstrating that FSN’s benefits encompass functional recovery and quality-of-life improvement beyond analgesia.

A primary objective of this study was to investigate whether FSN treatment was associated with changes in systemic inflammatory mediators. Our data demonstrate that FSN is associated with significant and sustained reductions in CRP, IL-1, and TNF-α, with the magnitude of reduction exceeding that observed in both the SH and MLX groups. The MLX group, despite being a direct COX-2 inhibitor, showed only transient changes, suggesting that pharmacological COX-2 inhibition alone is not associated with sustained reductions in these circulating inflammatory markers in KOA. It is important to note that these findings are associative and do not establish a causal relationship between FSN treatment and inflammatory mediator suppression.

The correlations between inflammatory marker reductions and clinical improvements are consistent with a potential mechanistic link but do not confirm causality. As a hypothesis-generating framework, FSN’s mechanical action on subcutaneous fascia and underlying pathological muscle may improve local microcirculation and tissue oxygenation, thereby reducing hypoxia-driven inflammatory signaling [23]. If such improvements occur, restoration of normal muscle function may break the pain-disuse-atrophy cycle, with a concomitant decrease in the release of damage-associated molecular patterns (DAMPs) and pro-inflammatory mediators. This could in turn attenuate systemic inflammatory burden, as reflected by the observed reductions in circulating CRP, IL-1, and TNF-α. However, periarticular muscle restoration was hypothesized but not directly measured in this trial.

The 38.5% reduction in TNF-α with FSN is particularly significant. TNF-α promotes muscle protein degradation via both the UPS pathway (MuRF1 and atrogin-1 upregulation) and NF-κB pathway [10]-[12]. These associations raise the hypothesis that FSN may simultaneously influence pathways related to muscle catabolism and joint cartilage destruction, potentially addressing the common inflammatory pathways linking muscle wasting and osteoarthritis [13]. This dual association—clinical improvement coupled with inflammatory marker reduction—is consistent with the hypothesis that FSN may exert therapeutic benefit through both local mechanical effects and systemic biochemical modulation; however, the observational nature of the cytokine data precludes causal inference. These findings align with the broader acupuncture literature showing modulation of inflammatory pathways including NF-κB suppression [24].

Our results extend previous findings. Liu et al. [17] reported superior short-term pain relief with FSN. Chiu et al. [18] demonstrated FSN efficacy for soft tissue pain. The systematic review by Zhao et al. [19] confirmed FSN improves pain and function, noting the need for longer follow-up and biomarker assessment. Our study addresses these limitations with 3-month follow-up, a three-arm design with active comparators, and comprehensive inflammatory marker data providing mechanistic insight. We employed rigorous methodology including concealed allocation, assessor blinding, and standardized outcome measures.

Our findings have important clinical implications. FSN represents a promising non-pharmacological treatment that provides superior symptom relief while addressing underlying muscle dysfunction—a key disease driver not targeted by SH or MLX. The sustained benefits suggest a brief 2-week course may produce durable improvement, potentially reducing the need for ongoing pharmacotherapy and its associated risks [25]. The association with reductions in inflammatory markers suggests that FSN may have effects beyond purely symptomatic relief, though causal relationships have not been established.

Several limitations should be acknowledged. Treating clinicians could not be blinded, though outcome assessors and analysts were blinded. The single-center design may limit generalizability; multi-center validation is needed. The 3-month follow-up, while longer than most previous FSN studies, is insufficient to assess very long-term outcomes. We measured only circulating serum markers; synovial fluid and tissue analyses would elucidate local mechanisms. Periarticular muscle restoration was hypothesized as a mediator of therapeutic benefit but was not directly measured in this trial. No sham FSN or placebo control was included. The observed associations between inflammatory markers and clinical outcomes are correlational; causal mediation analyses are needed to establish definitive pathways.