Effect of electroacupuncture for early ankle osteoarthritis: A randomized controlled trial using three-dimensional gait analysis

Abstract

Background

Ankle osteoarthritis (AOA) is a prevalent condition that affects joint function, often leading to pain, inflammation, and impaired mobility, significantly impacting patients’ quality of life.

Objective

This study explores the effects of electroacupuncture treatment on clinical outcomes and gait characteristics in patients with ankle osteoarthritis (AOA).

Methods

A total of 78 patients with AOA were randomly divided into a experiment group and a control group. The control group was treated with strength training, and the experiment group was additionally treated with electroacupuncture. The Ankle Osteoarthritis Scale (AOS), American Foot and Ankle Society's Ankle and Hindfoot Scale (AOFAS-AHS), and the 3D Motion Analysis System were used before and after the intervention to assess the clinical outcomes and changes in kinematic parameters in the AOA patients before and after therapy.

Results

After treatment, the differences in intra-group comparisons and inter-group comparisons of AOS scores, AOFAS-AHS scores, stride length, stride length, single-support phase, and gait variable scores (GVS) of ankle dorsiflexion-plantarflexion of the patients in the experiment group were statistically significant; the differences in inter-group comparisons of GVS scores of hip rotation of the patients in the experiment group were statistically significant; and the differences in the gait profile scores (GPS) and gait deviation indices of the patients in the experiment group were statistically significant. The differences in the intra-group comparisons were statistically significant. The within-group comparisons of AOS score, AOFAS-AHS score, GPS score and GVS score of ankle dorsiflexion-plantarflexion were statistically significant in the control group patients.

Conclusions

Electroacupuncture has shown promise as an adjunctive therapy for patients with AOA, offering a more holistic rehabilitation strategy. By improving joint mobility and optimizing gait mechanics, electroacupuncture can effectively reduce pain, facilitate the restoration of normal gait patterns, and enhance patients’ overall quality of life.

Introduction

Joint pain associated with arthritis impacts roughly 15% of the global adult population, ¹ with AOA comprising about 13% of all osteoarthritis cases. AOA is notably prevalent among Asian populations. ² The disease is caused by lesions in the cartilage, subchondral bone, and synovium of the affected joints. ³ Its pathogenesis involves aseptic inflammation, mechanical stress, and metabolic factors. Additionally, an imbalance between joint destruction and repair plays a significant role. ⁴ AOA is more prevalent among middle-aged and elderly individuals due to age-related laxity in the ligaments surrounding the ankle joint, which contributes to cartilage degradation and stress imbalances. The chronic nature, complexity, and variability of AOA, coupled with its poor prognosis, impose significant burdens on patients’ daily activities and mental well-being. ⁵ Symptoms of AOA typically emerge years after the initial injury, often leading patients to overlook the condition until it progresses to an advanced stage, where severe joint degeneration may result in impaired ankle function and potential disability. ⁶ Meanwhile, the pain and inflammation caused by osteoarthritis (OA) can significantly impact patients’ sleep quality, while sleep disturbances, in turn, increase inflammatory responses and pain sensitivity, exacerbating symptoms and ultimately affecting patients’ quality of life. ⁷ Therefore, it is particularly necessary for the treatment of early AOA, not only to reduce joint pain and stiffness, but also to improve joint mobility, slow down the progression of arthritis, and ultimately reduce the rate of limb disability.

Current clinical treatment of AOA is mainly based on the principles of other osteoarthritis treatments, including oral medication and local physiotherapy, but it often only provides temporary relief of ankle symptoms, while the long-term efficacy is poor, ⁸ and high dose or long term use of the drug is likely to cause liver and kidney damage. ⁹ How to quickly and effectively reduce patient pain, shorten the duration of the disease, and at the same time reduce the economic costs of the patient, thereby improving the quality of life of the patient, has always been a clinical problem that needs to be solved. Acupuncture treatment is a traditional rehabilitation therapy, which is characterized by the application of needles to acupuncture points, thus playing the role of supporting the positive and dispelling the negative, concurrently treating the liver and kidney, tonifying qi and blood, and addressing the sinews and bones, and its clinical efficacy is remarkable. Some studies have confirmed that acupuncture treatment can improve joint pain and function in patients with osteoarthritis.^10–12

At present, the clinical assessment of early AOA is mainly based on subjective scale assessment, especially pain assessment and functional assessment.^13,14 However, neither the scale assessment nor the doctor's visual inspection of the patient's walking ability can objectively quantify the efficacy of early AOA before and after treatment. The three-dimensional gait measurement of AOA belongs to the category of biomechanics and is also an important evaluation tool in clinical rehabilitation, which can be used to obtain important quantitative data about a patient's gait (including kinematics, kinetics, etc.), which cannot be easily mastered by two-dimensional video analysis or observational gait analysis. ¹⁵ It can concretize the functional activity changes of muscle and bone in osteoarthritis patients and is an important tool for the early diagnosis and identification of early AOA. Study indicate significant alterations in the spatiotemporal parameters and kinematics of the lower limbs in patients with early-stage AOA. ¹⁶ Although clinicians can observe abnormal gait in patients and improvement in abnormal gait patterns after treatment, quantitative assessment of gait dysfunction can be used as an objective complement to reduce bias in clinical decision making and improve clinician consistency in diagnosing and tracking disease progression. However, no studies have provided an in-depth analysis of the effect of acupuncture on the gait characteristics of patients with early AOA, as most studies have only looked at a few parameters of the gait cycle. Therefore, based on the 3D gait analysis electrodes for the clinical efficacy of AOA and the spatio-temporal parameters of the whole gait cycle (step speed, step length, step length, etc.), and the kinematics of each joint (flexion and extension, adduction and abduction, internal and external rotation, etc.), this study analyses in detail the gait characteristics of AOA patients before and after treatment, quantifies the gait changes of AOA patients and provides a basis for clinical treatment.

Methods

Study design

This study was a single-center randomized controlled clinical trial. This trial followed the CONSORT (Consolidated Standards of Reporting Trials) statement for practical clinical trials. The study protocol was conducted in accordance with the Declaration of Helsinki and approved by the Ethics Committee of Fujian Provincial Hospital (k2019-03-035).

Sample size

The sample size for this trial was determined using G*Power 3.1.9.2 software, based on the results of a pre-experiment and prior clinical experience. The effect size (Cohen's d) was set at 0.8, reflecting the anticipated large effect of electroacupuncture in improving pain in patients with ankle osteoarthritis (AOA). This value was supported by previous research, which showed significant improvements in pain with similar interventions. ¹⁷ The mean improvement in pain scores was expected to be 15–20 points, with a standard deviation (SD) of 10 points. ¹⁸ To achieve a power of 0.95 and an alpha level of 0.05, the minimum required sample size per group was calculated to be 35 patients. Taking into account a 10% dropout rate, the final sample size was increased to 39 patients per group, resulting in a total of 78 patients. This calculation also accounted for potential variability in treatment response and relevant confounders, ensuring the robustness of the study design.

Participants

The study population was selected from AOA patients who attended outpatient clinics at Fujian Provincial Hospital and surrounding community hospitals from May 2021 to August 2022. This study adopted a purposive sampling strategy to recruit participants, with recruitment conducted through online advertisements, posters distributed in hospitals and community outreach, in order to ensure the diversity of participants.

Inclusion criteria

The inclusion criteria were as follows: (1) Patients with a visual analog scale (VAS; range 0–100; higher scores indicate more severe pain) score of at least 40 on the severity of ankle osteoarthritis pain during daily activities and radiographic (anteroposterior and lateral views) evidence of tibial osteoarthritis of at least grade 2 on the van Dijk scale were eligible. ¹⁹ (2) aged between 40 and 80 years old; (3) had some ability to take care of themselves without other aids; (4) Kellgren-Lawrence classification of grade 1 or 2 unilateral ankle joint lesions; (5) strictly complied with the exercise instructions during the treatment period and could not perform strenuous exercise that may interfere with the experiment; and (6) agreed to sign the informed consent form and were willing to participate in this study.

Exclusion criteria

The exclusion criteria were as follows: (1) combined ankle gouty arthritis or other related diseases affecting the experiment; (2) local infection, rash, trauma, etc.; (3) bone and joint tuberculosis, severe osteoporosis, acute joint injury, rheumatoid arthritis, mental illness and other diseases; (4) combination with serious heart, brain, liver and kidney diseases; and (5) combination of spinal diseases, stroke, foot drop and other diseases that affect kinematic parameters.

Randomization and blinding

After completing general demographic information and baseline testing in 78 AOA subjects, the random allocation sequence was programmed by a dedicated statistical analyst not involved in the study process, utilizing the PROC PLAN procedure of the statistical software SAS 9.1. Eligible subjects were randomly assigned to the experimental and control groups in a 1:1 ratio, with 39 subjects in each group. To ensure balanced groups in terms of key variables such as age and severity of AOA, we employed block randomization techniques. The professional responsible for randomization securely maintained the random grouping sequence, while various parameters set during the randomization process, along with group allocations, were concealed using an opaque, airtight envelope. The allocation details were communicated to each participant via telephone.

Importantly, while the randomizer and outcome assessors were blinded to group assignments, we acknowledge that blinding of participants and clinicians was not feasible due to the nature of the intervention. To mitigate potential performance or detection bias, clinicians were rigorously trained to follow the treatment protocols.

Interventions

The control group

The control group performed ankle training using elastic bands in four directions: plantarflexion, dorsiflexion, inversion, and eversion. One end of the elastic band was securely attached to the anterior part of the foot, while the other end was fixed to a stable point. An initial force was applied, allowing the foot to push against the resistance of the band and move to its maximum range of motion. The foot held this position for 10 s before returning to the starting point. This movement was repeated 10 times, with a 3-s rest between each repetition. A set consisted of 10 repetitions, and participants completed one set daily, five days a week, over the course of four weeks.

The resistance level of the elastic bands was determined based on the rating of perceived exertion (RPE) scale. Participants used a resistance load that allowed them to perform a maximum of 10 repetitions, with the resistance adjusted to achieve an RPE score between 12 and 14. Muscle strength was measured every two weeks using a handheld dynamometer, providing objective data to monitor progress. The resistance level of the elastic band was then modified as needed to maintain optimal exercise intensity.

To promote muscle recovery, mild fatigue was encouraged; however, if a participant experienced significant fatigue, defined as a Borg CR-10 scale score above 4, they were instructed to rest or pause the exercise. Training resumed once the fatigue had subsided. This approach ensured that participants exercised within a safe and effective range, supporting muscle recovery and minimizing the risk of overexertion.

The experimental group

The experimental group received an additional 30-min electroacupuncture treatment on top of the control group's regimen. The main acupuncture points for electroacupuncture treatment included Jiexi, Taixi, Kunlun, Zusanli, and Yanglingquan; the allied points were taken according to the site of pain: Qiuxu, Xuanzhong, ShenMai, and Zulinqi of the foot for outer ankle pain; and Zhaohai, Rangu, Shangqiu, and Sanyinjiao for inner ankle pain. Jiajian brand 1-time acupuncture needles (0.30 × 25 mm, 0.30 × 40 mm) were used for needling. The body of the needle was held with a sterilized cotton ball, and the needle was inserted vertically using the flick method. Twisting was applied to all needles upon penetration so that qi was obtained under the needles, the flat tonic and flat diarrhea techniques were used with moderate stimulation, and the needles were retained at all points for 30 min, while the Huatuo brand electroacupuncture instrument (model: SDZ-II) was used to connect two groups of electroacupuncture needles (for the external pain: Jiexi and Kunlun, and the Zusanli and Yanglingquan; and for the medial pain: Jiexi and Taixi, and for the Zusanli and Yanglingquan). The continuous wave frequency was 100 Hz, 1x/d, 5 times per week for 4 weeks (Figure 1).

Figure 1.

Electroacupuncture intervention.

The acupuncture operation was performed by a clinical acupuncturist who had been practicing acupuncture for more than 5 years. In the event of adverse events such as syncope, needle retention, needle bending or folding, immediately stop treatment and take emergency measures, including rapidly lifting the needle, lying on the side of the head, eating sugar cubes or drinking sugar water, and instructing the patient to take deep breaths, etc., and make detailed records of the adverse reactions and measures taken. In the event of an event of higher severity and/or not manageable by existing countermeasures, prompt suspension of the programme and immediate medical attention is required.

Outcome measurements

Two assessors who had received professional training and were unaware of the intervention allocation assessed the subjects within 3 days prior to the intervention and within 3 days after completion of the intervention.

Primary outcomes

Pain intensity

The Ankle Osteoarthritis Scale (AOS) ²⁰ is a disease-specific assessment tool for ankle arthritis, demonstrating high overall reliability (r = 0.97; 95% confidence interval [CI]: 0.94–0.99), with excellent reliability for the pain subscale (r = 0.95; 95% CI: 0.90–0.98) and the disability subscale (r = 0.94; 95% CI: 0.88–0.97). The scoring method involves a visual analog scale, where each of the 18 items is represented by a line on paper, with 0 on the left (indicating no pain or full ability) and 10 on the right (indicating maximum pain or disability). The line is equally divided into 10 sections representing scores from 1 to 9, with each number corresponding to a specific score level.

Functional status

The American Orthopaedic Foot & Ankle Society Ankle-Hindfoot Scale (AOFAS-AHS), which is widely used to assess functional outcomes in ankle and hindfoot conditions. Studies have demonstrated strong reliability for the AOFAS-AHS, with ICCs ranging from 0.89 to 0.97, indicating excellent test-retest reliability. ²¹ Which consists of nine items with indicators of pain, function and voluntary movement, support, maximum walking distance (neighborhood), ground walking, paradoxical gait, anterior-posterior activity (flexion plus extension), hindfoot activity (inversion plus eversion), ankle-hindfoot stability (anterior-posterior and inversion-eversion), and foot force lines.

Secondary outcomes

Gait analysis

Three-dimensional gait data were acquired using a SMART-DX 400 infrared motion capture system (BTS, Italy). The data acquisition system consisted of eight infrared cameras (frequency: 50 HZ), two synchronized cameras (BTS eVixta, acquisition frequency 40 HZ), four force measuring platforms (BTS P6000D), an information conversion controller and a computer.

First, the researcher explained the process of gait acquisition and the requirements to the subjects to alleviate their concerns and ensure cooperation with the researcher. A total of 18 markers with appropriate diameters, which were selected with reference to the system module, were then placed on the body surface. The marker clusters on the lateral side of both lower limbs were secured by elastic bandages to serve as tracking points during exercise, and the remaining markers were attached to the body surface with medical anti-allergic double-sided adhesive tape. After the markers were placed, the subjects were instructed to walk back and forth on the 8-meter-long walkway at the most natural and comfortable pace and waited for the subjects to get used to the markers and the surrounding environment before the spatiotemporal parameters and kinematic parameters were collected.

In addition, specific indicators in kinematic parameters are collected, including: (1) the gait deviation index (GDI) is commonly used to reflect overall gait variability by calculating the degree of deviation of the patient's gait kinematic characteristics of the pelvis, hips, knees, and ankles from the mean of the reference dataset ²² ; (2) the gait profile score (GPS) describes the asymmetry of gait and the relative magnitude of deviation of kinematic variables by simplifying complex operations, ²³ and in general, the GPS is negatively correlated with gait quality ²⁴ ; (3) the gait variable score (GVS) is a decomposition of the GPS into 9 variable scores for different joints to reflect the degree of deviation of individual joint gait variables, ²⁵ and there are 9 clinically important gait variables (left-right pelvic tilt, anterior-posterior pelvic tilt, pelvic rotation, bilateral hip flexion/extension, bilateral hip adduction and abduction, bilateral hip rotation, bilateral knee dorsiflexion/extension, bilateral ankle dorsiflexion/extension, and bilateral foot advancement angles).

The above measurements were taken five times and the results were averaged.

Statistical analysis

Statistical analysis was performed using IBM SPSS Statistics 23.0 software. Measurement data were expressed as the mean ± standard deviation (mean ± SD), and count data were described by frequency, percentage, or composition ratio. For within-group analyses, paired-sample t-tests were used for normally distributed data, while Wilcoxon signed rank sum tests were used for non-normally distributed data. Independent-sample t-tests were applied for between-group comparisons for normally distributed data. For multiple comparisons, we applied the Bonferroni correction to adjust for potential type I errors. All tests were two-sided, with a significance level of α = 0.05. A P-value of ≤ 0.05 was considered statistically significant, adjusted accordingly where applicable.

Results

At the 4-week mark, 73 out of 78 eligible participants successfully completed the assessment. During the course of the exercise intervention, 2 participants from the experimental group and 3 from the control group withdrew from the study and were lost to follow-up. Ultimately, 37 participants in the experimental group and 36 participants in the control group completed the full 4-week intervention (Figure 2). There were no differences between the two groups of participants to the extent allowed by the baseline comparison (Table 1).

Figure 2.

CONSORT diagram of the eligibility, exclusion and randomization scheme.

Table 1.

Baseline demographic of the participants (`x ± s).

	Experiment group (n = 37)	Control group (n36)	t/Z/χ2	P
Sex (male/female)	5/32	8/28	0.945	0.331
Affected side (right/left)	14/23	16/20	0.329	0.566
Age	67.73 ± 6.95	67.22 ± 5.13	0.354	0.724
Height (cm)	159.77 ± 6.26	160.92 ± 6.8	−0.749	0.456
Weight (kg)	63.14 ± 12.90	63.57 ± 8.87	0.569	0.569
BMI (kg/m2)	24.73 ± 4.79	24.49 ± 2.53	0.513	0.608

BMI: Body Mass Index.

There was no statistically significant difference in the comparison of the parameters between the two groups before treatment. After treatment, there were statistically significant differences in the AOS score and AOFAS-AHS score between the experiment group and the control group and within the group before treatment (P < 0.05); the within-group differences between the control group after treatment and before treatment were also statistically significant (P < 0.05) (Tables 2 and 3).

Table 2.

Comparison of AOS scores of study subjects (`x ± s).

	Experiment group	Control group	t/Z	P
Pre-intervention	78.51 ± 23.06	69.53 ± 18.87	1.819	0.073
Post-intervention	20.76 ± 19.35	39.06 ± 19.60	3.386	0.000
t/Z	−5.243	8.673
P	0.000	0.000

Table 3.

Comparison of the AOFAS-AHS scores of the study participants (`x ± s).

	Experiment group	Control group	t/Z	P
Pre-intervention	67.19 ± 16.32	71.78 ± 11.90	−1.369	0.175
Post-intervention	89.22 ± 10.17	78.61 ± 11.26	−3.994	0.000
t/Z	−8.781	−2.132
P	0.000	0.040

The intragroup differences in stride length, step length, and single-support phase in the experiment group and before treatment and the intergroup differences with the control group were statistically significant (P < 0.05) (Table 4).

Table 4.

Comparison of spatiotemporal parameters at pre-intervention and post-intervention among the two groups (`x ± s).

	Experimental group		Control group
	Pre-intervention	Post-intervention	Pre-intervention	Post-intervention
Speed (m/s)	1.00 ± 0.18	1.37 ± 2.14	1.07 ± 0.18	1.0 ± 0.20
Stride Length (m)	1.05 ± 0.15	1.12 ± 0.11ab	1.08 ± 0.14	1.04 ± 0.17
Step Length (m)	0.51 ± 0.13	0.57 ± 0.13ab	0.53 ± 0.87	0.50 ± 0.87
Mean Velocity (steps/min)	107.22 ± 14.63	108.82 ± 13.42	108.41 ± 6.87	106.69 ± 18.52
stride width (m)	0.09 ± 0.03	0.09 ± 0.02	0.09 ± 0.04	0.10 ± 0.03
Swing Phase (%)	37.82 ± 4.35	38.65 ± 3.60	38.69 ± 5.07	39.23 ± 2.25
Stance Phase (%)	58.78 ± 6.61	59.32 ± 5.89	60.65 ± 2.64	60.32 ± 4.47
Double Support Phase (%)	13.10 ± 5.08	11.87 ± 4.79	11.69 ± 5.06	12.97 ± 4.54
Single Support Phase (%)	37.00 ± 4.41	41.82 ± 5.15ab	36.06 ± 5.18	39.58 ± 3.35

^a Denotes a difference significant at P < 0.05 when compared with pre-intervention values.

^b Denotes a difference significant an P < 0.05 when compared with the control group.

There was a statistically significant (P < 0.05) between-group difference in GVS values for hip rotation and ankle dorsiflexion-plantarflexion in the experiment group and the control group. After treatment, there was a statistically significant (P < 0.05) within-group difference in GVS values for GPS, GDI and ankle dorsiflexion-plantarflexion in the experiment group and the pretreatment group; the within-group differences in GPS variables and GVS values for ankle dorsiflexion-plantarflexion in the control group after treatment and the pretreatment group were statistically significant (P < 0.05) (Table 5).

Table 5.

Comparison of kinematic parameters at pre-intervention and post-intervention among the two groups [°, (`x ± s)].

Item	Experimental group		Control group
	Pre-intervention	Post-intervention	Pre-intervention	Post-intervention
Pelvic Obliquity	2.58 ± 1.50	2.78 ± 1.38	2.35 ± 0.84	2.45 ± 1.10
Pelvic Tilt	7.63 ± 4.91	9.21 ± 5.61	5.67 ± 4.09	7.46 ± 4.60
Pelvic Rotation	3.89 ± 1.13	3.88 ± 1.16	4.27 ± 1.30	4.31 ± 1.44
Hip Ab-Adduction	4.79 ± 2.75	4.60 ± 2.24	4.22 ± 2.42	4.56 ± 1.91
Hip Flex-Extension	10.02 ± 5.76	10.74 ± 7.20	8.48 ± 4.29	9.86 ± 4.88
Hip Rotation	11.89 ± 6.02	14.85 ± 9.90ab	11.82 ± 6.31	10.36 ± 6.23
Knee Flex-Extension	10.10 ± 4.75	9.62 ± 5.30	9.08 ± 4.11	9.77 ± 3.42
Ankle Dors-Plantarflex	7.10 ± 3.41	5.43 ± 2.09ab	7.78 ± 3.00	6.59 ± 2.65 a
Foot Progression	7.98 ± 4.12	7.52 ± 4.03	8.28 ± 6.76	7.34 ± 3.68
GPS	9.03 ± 2.52	7.63 ± 2.38 a	9.03 ± 2.32	7.99 ± 1.84 a
GDI	85.57 ± 11.51	91.29 ± 10.80 a	84.83 ± 11.78	89.44 ± 10.53

^a Denotes a difference significant at P < 0.05 when compared with pre-intervention values.

^b Denotes a difference significant an P < 0.05 when compared with the control group.

Discussion

Adding electroacupuncture to strength training can further improve pain and dysfunction in patients with early AOA. Additionally, there was a significant improvement in the patient's walking style and gait quality. Studies shows that patients with AOA suffer from pain and swelling due to damage to the articular cartilage, which in turn results in limited walking ability and has a serious impact on gait.^26,27 Bytyçiet al. believe that patients with AOA are unable to return to a normal physiological gait in the short term after injury, and patients use reduced walking speed, shorter stride lengths, and reduced stride lengths to maintain safety. ²⁸ Previous studies by our team have found that speed, stride length, stance phase, and single support phase are significantly reduced, while stride width and double support phase are significantly increased in early-stage AOA patients compared to normal subjects. ²⁹ Therefore, in our study, we observed significant improvement in step length, stride length, and single support phase in early AOA patients, indicating that four weeks of electroacupuncture treatment has a notable impact on these gait parameters. The improvements in stride length and single support phase suggest that electroacupuncture may enhance muscle activation and neuromuscular coordination, leading to a more stable and efficient walking pattern. Electroacupuncture is thought to stimulate motor points and improve the neuromuscular connection, which can help restore more normal muscle function in AOA patients.^30,31 This aligns with previous studies, which have demonstrated that electroacupuncture improves walking automation and muscle strength in patients with osteoarthritis. ³² Additionally, we observed significant alterations in GVS values for ankle plantarflexion, dorsiflexion, and hip rotation, as well as in GPS and GDI values, further suggesting that electroacupuncture therapy contributes to improved walking strategy and overall gait quality in early AOA patients. These results suggest that electroacupuncture helps restore the natural dynamics of gait, potentially by reducing pain, improving joint flexibility, and promoting better motor control. This may explain the improvements in walking strategy observed in this study and supports the therapeutic benefits of electroacupuncture for AOA patients.

Although traditional strength training increases muscle strength, the resistance and trajectory are not easy to control, so the effect of muscle strength improvement is not obvious, and early AOA patients are affected by pain, strength training is often ineffective. Langeard et al. demonstrated that ankle training can significantly enhance gait kinematics without notably affecting spatiotemporal parameters. ³³ In this study, we added electroacupuncture, which is an organic combination of electrical stimulation and millimetre needling, to conventional strength training. Electroacupuncture works by delivering electrical impulses to the target peripheral nerves, thereby activating the muscles. When used alongside strength training, this approach aims to maximize improvements in functional impairment for the patient. Study have shown that electroacupuncture can increase the body's pain threshold and produce long-lasting analgesic effects by promoting the release of endogenous analgesic substances such as morphine peptide. ³⁴ In this study, low-frequency continuous waves were used to promote blood circulation, stimulate acupoints, relieve various muscle joint, ligament and tendon injuries, and improve the therapeutic efficacy of millimeter needling while providing an analgesic effect. ³⁵ Electroacupuncture alleviates pain and inflammation primarily by activating endogenous opioids, such as enkephalins and endorphins, and by modulating inflammatory mediators. Specifically, Electroacupuncture reduces levels of pro-inflammatory cytokines, including IL-1β and TNF-α, while enhancing the expression of anti-inflammatory cytokines, such as IL-10. Additionally, electroacupuncture has been shown to swiftly alleviate knee OA symptoms and signs, potentially by modulating the gut microbiome composition, specifically reducing the abundance of Streptococcus. ³⁶ This bioregulatory effect positions electroacupuncture as a promising lifestyle intervention within a holistic approach to OA management, suggesting it may offer preventive and therapeutic benefits through microbiome modulation. ³⁷

However, subjective scales reflect only the patients’ personal perceptions, and objective data are needed to substantiate the functional improvements achieved by selectively targeting early-stage AOA patients. The lower limb functions as an integrated unit, with the muscles, bones, and joints in its kinetic chain activating in a specific sequence based on movement characteristics. Weak areas within this chain can be compensated by adjacent structures to achieve the intended movement. For example, when ankle joint flexibility decreases, the body may adapt by reducing stability in the hip and knee joints to enhance overall flexibility. ³⁸ In patients with AOA, an abnormal mechanical environment within the ankle joint induces morphological and functional changes, leading to symptoms such as ankle pain and restricted plantarflexion-dorsiflexion. To mitigate pain during the gait cycle, patients often rely on compensatory mechanisms in the hip and knee joints, which subsequently contribute to gait abnormalities. Therefore, this study believes that we need to analyze the overall gait changes of the three joints of the lower extremities, rather than focusing on the changes of several parameters of a single joint.

Gait analysis in biomechanics encompasses parameters such as kinematic, spatio-temporal, kinetic, electromyographic activity, and energy metrics. These parameters can be accurately assessed by synchronously capturing data with an AOA tracking system and a three-dimensional force platform, allowing precise measurement of joint kinematics and dynamics during movement. This quantitative approach enables dynamic analysis of lower limb movement and loading conditions, facilitating assessments of walking automation, efficiency, and quality. Therefore, this study tested the spatio-temporal parameters and kinematic characteristics of early AOA patients before and after treatment and comprehensively assessed the gait changes of early AOA patients. This study found that after four weeks of electroacupuncture treatment, early-stage AOA patients showed significant improvement in ankle dorsiflexor function, with increases in step width, stride length, and single-limb support phase. Study indicate that stride length, step length, and the single-limb support phase are key parameters influencing body balance during walking in the elderly. ³⁹ Meanwhile, the ankle dorsiflexor muscles play a crucial role during the toe-off and swing phases of the gait cycle, facilitating foot clearance and forward progression. In addition, this study also found that GPS and GDI scores both improved in early-stage AOA patients after four weeks of electroacupuncture treatment. The GPS and GDI are both indicators that quantify overall gait quality, with GPS representing deviations from normal gait and GDI reflecting the degree of gait abnormalities relative to a healthy control.^40,41 These findings suggest that electroacupuncture may enhance the activation of key muscle groups involved in gait, particularly the dorsiflexors, which play a crucial role in the propulsion and stabilization phases of walking. The observed increases in stride length and single-support phase indicate not only an improvement in walking function but also potential gains in neuromuscular coordination and walking automaticity in early AOA patients. By enhancing foot placement control and forward propulsion, electroacupuncture likely contributes to a more efficient and coordinated gait pattern. This improvement in walking automaticity is essential for enhancing overall mobility and reducing fall risk in AOA patients, as it supports smoother and more stable movement. ⁴²

Finally, we conducted an analysis of GVS values for the three primary lower limb joints, observing a decrease in GVS values for ankle plantarflexion and dorsiflexion, alongside an increase in GVS values for hip rotation. During gait, continuous body rotation facilitates weight transfer, with hip rotation propelling the body forward. ⁴³ In the swing phase, the tibialis anterior muscle engages ankle dorsiflexion to lift the forefoot, increasing clearance and extending stride length. In patients with AOA, however, ankle pain commonly weakens the plantarflexor and dorsiflexor muscle groups. ⁴⁴ Since plantarflexors are crucial for forward propulsion and postural stability, this weakness causes AOA patients to compensate with hip mechanisms rather than relying on ankle function. As a result, hip rotation increases as a compensatory measure, requiring coordinated action from hip internal and external rotators. After a four-week intervention, improvements in ankle plantarflexor and dorsiflexor strength were evident, enabling early-stage AOA patients to achieve forward weight shifting through consistent ankle dorsiflexion-plantarflexion movements, thereby lessening dependence on compensatory hip strategies. In conclusion, electroacupuncture's anti-inflammatory and analgesic effects contributed to enhanced ankle muscle strength and flexibility, improved dorsiflexion-plantarflexion range, and optimized gait mechanics in AOA patients, resulting in better overall gait quality.

Limitations

This study has several strengths, including the use of electroacupuncture as an effective treatment modality for ankle osteoarthritis (AOA) and the analysis of kinematic characteristics, which provides objective data on the clinical efficacy of electroacupuncture. However, there are also notable limitations. First, while we collected spatiotemporal gait parameters and kinematics of AOA patients walking on flat ground at self-selected speeds, we did not account for different walking conditions, such as varying speeds or obstacles, which may limit the generalizability of the results to more complex, real-world scenarios. Additionally, the walking path used during the experiment was relatively short due to site constraints. This limitation prevented us from recording spatiotemporal parameters and kinematics after prolonged walking, which may have provided valuable insight into fatigue-related changes in gait patterns. Another important limitation is the short duration of the treatment, only four weeks, without long-term follow-up. As a result, we are unable to fully assess the sustainability of electroacupuncture's effects over time.

Future research should aim to address these limitations by conducting larger, multicenter, high-quality studies with extended treatment durations and long-term follow-up. Longer-term studies are especially crucial to evaluate the lasting effects of electroacupuncture and to determine whether the observed improvements are maintained over time. Additionally, such studies should include the observation of AOA patients in varied conditions (e.g., different speeds, obstacles) to provide a more comprehensive view of the biomechanical changes across different disease stages. This approach will help establish a more complete understanding of the long-term efficacy and biomechanical performance of electroacupuncture for AOA patients.

Clinical implications

This study demonstrates that in patients with early-stage ankle arthritis, the addition of electroacupuncture to standard strength training can significantly enhance ankle joint function. Furthermore, 3D gait analysis showed that electroacupuncture not only improves walking efficiency but also has a notable impact on optimizing ankle plantarflexion and dorsiflexion angles during gait. These findings suggest that electroacupuncture could serve as an effective adjunct therapy, complementing strength training approaches.

The clinical significance of this study lies in the potential for electroacupuncture to provide a more holistic and targeted rehabilitation strategy. By addressing both functional improvements in joint movement and overall gait mechanics, electroacupuncture can contribute to a more effective recovery process for early-stage ankle arthritis patients. This integrative approach could play a crucial role in restoring normal gait patterns, reducing pain, and ultimately enhancing patients’ quality of life. Additionally, the ability to improve mobility and prevent further joint degradation may reduce the long-term need for more invasive treatments.

Conclusions

This study demonstrates that adding electroacupuncture to strength training significantly improves ankle joint function in early-stage ankle arthritis patients. The 3D gait analysis revealed enhanced walking efficiency and optimized ankle plantarflexion and dorsiflexion angles. Clinically, these findings suggest that electroacupuncture can be an effective adjunct therapy, offering a more comprehensive rehabilitation strategy. By improving joint movement and gait mechanics, electroacupuncture may reduce pain, restore normal gait, and improve overall quality of life. Future research should focus on long-term efficacy and explore its broader application in different stages of ankle arthritis.