Previous evidence showed that acupuncture can help alleviate pain associated with osteoarthritis (OA) of the knee (Berman et al., 1995). Many research studies have examined the effects of acupuncture on pain and joint mobility in patients with OA of the knee (Berman et al., 2004; Sangdee et al., 2002; Scharf et al., 2006; Tukmachi, Jubb, Dempsey, & Jones, 2004; Witt et al., 2005; Witt et al., 2006). A systematic review suggested that acupuncture was an option worthy of consideration, particularly for knee OA (Kwon, Pittler, & Ernst, 2006). This study hypothesized that pain relief resulting from acupuncture might motivate patients to increase physical activity. In the hope of facilitating the integration of acupuncture into conventional medicine, this study quantitatively evaluated the effectiveness of acupuncture on pain and mobility in patients with osteoarthritis of the knee.
Osteoarthritis of the Knee
Osteoarthritis is a chronic medical condition that involves the gradual destruction of one or more joints (Felson, 2006). Osteoarthritis has been identified as a leading cause of impaired mobility in the elderly (Peat, McCarney, & Croft, 2001). The joint most commonly affected by osteoarthritis is the knee (Felson & Zhang, 1998; Oliveria, Felson, Reed, Cirillo, & Walker, 1995). Osteoarthritis of the knee is a common medical problem in Taiwan as well. Approximately 3,000 knee replacements are done on an annual basis in Taiwan. These surgeries place a huge burden on the health care system, requiring average hospital stays of 10 days and annual costs of $66,025 to $79,230 (Taiwan dollars) per patient (Hsu, 1993).
Typical complaints of patients with osteoarthritis of the knee are pain, stiffness, inflammation, swelling, tenderness, and grinding on affected knee joints, as well as decreased activity (Buckley, Vacek, & Cooper, 1990). Therefore, main treatment priorities include pain relief and improved mobility (Ausiello & Stafford, 2002; Banning, 2006; Felson, 2006; Wegman, van der Windt, van Tulder, Stalman, & de Vries, 2004). However, the effects of nonsteroidal anti-inflammatory drugs are small and short-lived (Bjordal, Ljunggren, Klovning, & Slørdal, 2004), and these drugs have been associated with serious side effects, including bleeding and perforated ulcers (Brien, Lewith, & McGregor, 2006; Gutthann, Garcia Rodriguez, & Raiford, 1997). Consequently, many people with osteoarthritis of the knee seek alternative treatments, such as acupuncture.
The general theory of acupuncture is based on the premise that there are patterns of energy flow (Qi) through the body that are essential for health (Stux, 1987a). This Qi can be traced through various body systems and along 12 main pathways known as meridians. Most illnesses and disturbances are caused by either an excess or deficiency of Qi in organ systems and meridians (Stux & Pomeranz, 1987). Acupuncture may correct imbalances of the Qi at identifiable acupuncture points close to the skin along meridians. The number and length of treatments and acupuncture points used may vary among individuals and during treatment.
In traditional Chinese medicine, five Zang-fu networks refer to the gross anatomical entities of the internal organs and physiological functions (Veith, 1972). The Heart network propels the blood and is the seat of consciousness. The lung network receives and disperses Qi. The spleen network generates and distributes nourishment and fluid to the heart and the lungs from where such are distributed to nourish the whole body. The liver network stores the blood, regulates the even movement of Qi, and regulates the volume of blood circulating. The kidney network stores the Qi, manufactures blood, and dominates fluid metabolism. The underlying mechanism of osteoarthritis of the knee is considered as slowdown of Qi, the consequence of ineffective interaction between liver, spleen and kidney networks. Osteoarthritis of the knee is characterized by blood stasis and sputum accumulation. This study attempted to relieve pain by relaxing muscles and tendons using a strategy targeted to strengthen liver, gall bladder, and spleen networks. Treatment in this study focused mainly on activating the blood to resolve stasis, promote smooth circulation of blood and Qi to relax muscles and tendons, and disperse blockages along the meridians to relieve pain.
Individualized acupoints were chosen from Zhenjiu Dacheng (Compendium of Acupuncture and Moxibustion, A.D. 1601) a work by Yangjizhou, a Ming Dynasty acupuncturist. All acupoints selected have been reported to give maximum relief to patients with pain, and to enhance immune system functions (Stux & Pomeranz, 1987). Three acupuncture points that were universally applied to all experimental group subjects included the Dubi (Stomach 35) (Berman et al., 2004; Sangdee et al., 2002; Witt et al., 2005), Xiyan (Extra 32) (Berman et al., 2004; Sangdee et al., 2002; Scharf et al., 2006; Tukmachi et al., 2004) and Yanglingquan (GallBladder 34) (Berman et al., 2004; Scharf et al., 2006; Tukmachi et al., 2004; Witt et al., 2005). Treating Yanglingquan has been reported to have beneficial effects on knee disorders, rheumatoid arthritis, tendovaginitis, myodystrophies, myopathy, and mental disorders (Stux, 1987b). Dubi and Xiyan are recommended for use together as local acupuncture points for treatment of knee joint disorders. Yanglingquan and Dubi are located on the lateral side at the lower border of the patella. Xiyan is located on the medial side of the ligamentum patella.
Additional acupuncture points for pain relief were applied to address symptoms specific to each patient in the experimental group. Complaints of pain on the internal side of the knee joint recommended the addition of three points, including Yinlingquan (Spleen 9) (Berman et al., 2004; Scharf et al., 2006; Tukmachi et al., 2004), Xuehai (Spleen 10) (Scharf et al., 2006; Witt et al., 2005), and Taixi (Kidney 3) (Berman et al., 2004; Vas et al., 2004; Witt et al., 2005). Yinlinquan is recommended for treating disorders of the edema, ascites and swelling in the lower extremities. Xuehai is recommended for treating skin disorders, allergies, infectious disorders, blood diseases and urogenital disorders. Taixi is recommended for treating urogenital disorders, enuresis, dysmenorrhea, impotence, cystitis and disorders of upper ankle joints (Stux, 1987b). Yinlingquan is located on the medial side of the leg, in the depression below the lower border of the medial condyle at the level of the tuberositas tibiae. Xuehai is located on the highest point of the muscle vastus medialis, 6 cm proximal to the upper border of the patella. Taixi is located midway between the most prominent point of the malleolus medialis and the superior border of the Achilles' tendon.
Complaints of pain on the external side of the knee joint recommended the additional application of acupuncture therapy at the Liangqiu (Stomach 34) (Scharf et al., 2006; Witt et al., 2005). Liangqiu, recommended for treating disorders of the knee joint and acute gastrointestinal disorders (Stux, 1987b), is located 6 cm above the lateral and superficial border of the patella. Complaints of pain on the top side of the knee joint recommended the additional application of acupuncture therapy at the Heding (Extra 31) (Witt et al., 2005). Heding is recommended for knee joint pain relief and is located at the midpoint of the upper border of the patella. Pain on the posterior side of the knee recommended the addition of Weizhong (Urinary Bladder 40) to the acupuncture therapy program (Tukmachi et al., 2004). Weizhong, recommended for relieving lumbago, sciatica, pelvic disorders, impotence and enuresis (Stux, 1987b), is located at the midpoint of the popliteal transverse crease. All acupoints were used bilaterally.
This was a two-group prospective, quasi-experimental, pilot study conducted over a four week period (Parson, 1993). After data collection was completed in the experimental group, researchers collected data from the control group. Adjunctive to biomedical standard care comparisons assesses the efficacy of acupuncture plus standard care relative to standard care alone (Hammerschlag, 1998). The Institutional Ethical Committee approved our use of this protocol.
Selecting and Assigning Patients
A non-probability purposive sample was drawn from patients who visited the Department of Orthopedics as outpatients. Patients were selected according to seven criteria including: aged 55 years or older; diagnosis using Western medical techniques or radiological evidence of Grade 1, 2, or 3 knee OA; at least moderate pain in one knee for most of the past month; no evidence or history suggesting (a) pregnancy, (b) systemic steroid therapy or intra-articular steroid injections in the 3 months prior to the study, (c) coexistent joint diseases (such as rheumatoid arthritis, fibromyalgia, prior total knee replacement surgery), (d) severe chronic or uncontrolled serious illness (such as diabetes, stroke), or (e) history of bleeding diathesis. After written informed consent and full medical histories were obtained from each patient, experimental group data was collected first. Control group data was then collected. Of the 62 participants (37 in experimental group, 25 in control group) who initially agreed to participate in this study, 38 withdrew during week four (25 in the experimental group, 13 in the control group). Withdrawals included, but were not limited to, patients in the experimental group who failed to complete a full course of treatment. Twenty-four patients (n = 24) completed the full course of treatment; the attrition rate was 37%. The final group sizes were: acupuncture, n = 12; and control, n = 12.
All patients were asked to maintain their current level of oral medication (i.e., nonsteroidal anti-inflammatory drugs, cyclooxygenase-2 inhibitors, and acetaminophen) and physiotherapy (e.g., isotonic resistance exercise on quadriceps and locally applied heat on affected knee) throughout the experiment. The control group only received such standard treatments. No subjects received any steroids, but all took oral analgesics. All subjects received instruction regarding proper use of all medication, decreased activity, and joint and muscle stretching exercises.
Patients in the acupuncture group completed a total of 8 sessions of 30 minutes each, which were administered two times weekly over a four week period. A total of 6-9 acupuncture points were addressed in each patient. Dr. Sun, co-investigator of this study, assessed patient conditions and performed acupuncture. Dr. Sun is the director of the Department of Acupuncture and Chinese Traumatology and has practiced acupuncture independently for more than 20 years, with expertise in the treatment of soft tissue pain and allergy conditions. During acupuncture treatment, each subject assumed a supine position to promote relaxation and prevent fainting. Disposable sterile 34-gauge stainless steel needles (0.22 mm diameter, 2.5 cm length) were used and inserted to depths of 0.5-2 cm into the acupoints. Once subjects verified the “De Qi” sensation, the physician would not stimulate the acupoints but apply electricity to one of two-point groups (either Dubi and Xiyan or Yanglingquan) and one of the other six points (Yinlinquan, Xuehai, Taixi, Liangqiu, Heding or Weizhong). Electricity was delivered at 2-5 V (amplitude of pulse), 2 Hz (low-frequency), D-D wave for 15 min. In addition, a tiny cone of moxa was placed on the top of the needle on all points used except Weizhong and ignited for 3 minutes. Acupuncture needles then remained in place for another 12 minutes without stimulation while subjects rested.
The acupuncture points were identified using a flexible point selection formula. Such included local points around the affected knee and the distal points at medial and lateral aspects of the leg. Low-frequency (2 Hz) electroacupuncture was selected because it produces an analgesia of long duration, which outlasts the 20-min stimulation session by 30 mins to many hours. In addition, its effects are cumulative after several sessions of treatment are given on a daily or less frequent basis (2-3 times a week) (Sangdee et al., 2002). For these reasons, low-frequency electroacupuncture in this study was applied twice weekly for 4 weeks, as commonly recommended in electroacupuncture practice.
Three measurements were performed at the beginning and the end of the 4 week treatment period. These included: the six-minute walking distance (6-MWD) (Butland, Pang, Grossk, Woodcock, & Geddes, 1982), the pain visual analogue scale and outcome measurement the osteoarthritis of the knee. For 6-MWD, subjects were asked to walk for 6 minutes at their own maximal pace along a 40-meter long hospital corridor, stopping as necessary, at room temperature with researcher accompaniment and encouragement. Distance actually walked was measured in meters. Pain visual analogue scale refers to a 100-mm horizontal line, with anchors defined as “no pain” at the low end and “extreme pain” at the high end.
The osteoarthritis of the knee outcome measurement was developed in Taiwan. This instrument showed acceptable construct validity, explaining 52.34% of total variance in factor analysis and showing internal consistency ranging from 0.79 to 0.90 for five subscales in a previous study (Yang, Maa, Hsu, & Wu, 2001). The questionnaire includes 37 items designed to reflect a respondent's degree of distress toward activities of daily living in terms of pain, symptoms, mobility, emotional reactions and social participation. Items are weighted and each section yields a value between 0 and 100 on an internal scale, with the worst state rated as 100 and the best rated as 0.
All data were analyzed using SAS/STAT version 9.1. Participants who dropped out of the study were not statistically different from those who completed the study in terms of age, gender, and pain visual analogue scale results. Therefore, only data for those participants who completed the study were analyzed. To account for dependence within subjects due to repeated measurements of outcome variables, generalized estimating equations (GEE) were used throughout the analysis. Statistical tests were two-sided and comparisons with a p-value < .05 were considered statistically significant.
The Institutional Ethical Committee approved the protocol. Patients signed a written consent form before participating in this study.
Table 1 lists sample baseline demographic characteristics. No significant differences were identified between subjects in the experimental and control groups. Considered together, the mean age of all participants was 60.08 years, their mean body mass index was 26.55, and their mean period of osteoarthritis of the knee history was 2.61 years. The sample contained more females (n = 20) than males (n = 4).
Table 2 shows the mean values (± standard deviation) of the outcome variables for all participants at the baseline and after 4 weeks. The results of multiple linear regression analysis for longitudinal data are reported in Table 3. Estimates of linear regression coefficients and standard errors (SE), obtained using the GEE method with working correlation = AR (1) (1st-order autoregressive process), are provided. As shown in Table 3, after controlling for the effects of age, gender, body mass index, and osteoarthritis of the knee history (3 years or longer and 2 years or shorter as separate variables), both acupuncture and control groups showed significant improvement with respect to time effects at 4 weeks in terms of six-minute walking distance, pain visual analogue scale, pain domain and mobility domain scores determined by the osteoarthritis of the knee outcome measurement (p < .01).
This study found that both the experimental and control group showed improvements in six-minute walking distance, pain visual analogue scale, pain domain and mobility domain scores as determined by the osteoarthritis of the knee outcome measurement, after adjusting for covariables. However, the degree of improvement in the experimental group did not differ significantly from that in the control group. The clinical implications of these findings are consistent with the goals of osteoarthritis of the knee treatment (Ausiello & Stafford, 2002; Wegman et al., 2004).
Recruitment and Attrition
The high attrition rate in this experiment may be attributable to the nature of acupuncture. Of the 38 subjects in the acupuncture group who dropped out in week 4, five refused to accept acupuncture treatment, six dropped out because participation was too time-consuming, seven withdrew due to fear of SARS (Severe Acute Respiratory Syndrome) infection and twenty withdrew without giving specific reasons. That most of the withdrawals were not for medical reasons reflects the fact that some patients may not have appreciated the value of acupuncture.
Although the experimental group had negative scores on demographic and clinical characteristics such as age, BMI and osteoarthritis of the knee history (Table 1), this group still had more positive scores on post-test outcome measure (Table 2) compared to the control group. That result implies that improvement in patient's six-minute walking distance, pain and mobility after acupuncture treatment might be explained by the activation and strengthening of the body's natural defenses and repair systems with minimal side effects (NIH consensus conference, 1998). Apart from hematomas, no obvious adverse effects due to acupuncture were detected, which supports statements on the general safety of acupuncture (Melchart et al., 2004). Our results confirmed the findings of 3 previous trials that used acupuncture with electrostimulation (Berman et al., 2004; Sangdee et al., 2002; Vas et al., 2004).
Overall results of this study may have been affected by disappointment among control group patients in not receiving adjunctive care. Limitation of this study included a lack of randomizing participants into the two groups and the possibility that the observed effectiveness of acupuncture may be attributable to placebo effects. Also, due to the nature of the intervention, it was not possible to blind acupuncturists to treatment. Thus, results might be biased due to a lack of adequate blinding. Other study limitations include not obtaining information on how acupoints were selected for each patient in the acupuncture group or on other treatment modalities that might have affected outcomes. Future studies should interview patients and their families on several occasions to obtain information about other treatment modalities practiced (e.g., meditation, exercise and nutrition) as well as co-existing medical conditions.
Patients with osteoarthritis of the knee appear to experience clinically significant improvements measured in terms of six-minute walking distance, pain relief and mobility when standard care is supplemented with acupuncture. In spite of issues of patient compliance and attrition, our findings support the place of acupuncture in the multimodal treatment of patients with osteoarthritis of the knee. Similar studies must be undertaken with a larger patient population using randomized allocation. A larger population would permit a determination of the effect on outcomes, if any, of compliance. Further investigation is necessary to determine whether acupuncture provides long-term improvement in pain and function and whether the mechanism of the observed effect of acupuncture is possibly due either to physiological effects or to the greater intensity of physician contact experienced by those in the experimental group.
This study was supported by grant NSC 91-2320-B-182A-008 from the National Science Council of the Republic of China.
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Key Words:: acupuncture; osteoarthritis of the knee; osteoarthritis of the knee outcome measurement.
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