Joint Proprioception in Normal and Osteoarthritic Knees
Ashish Kumar*
National Institute for Orthopedically Handicapped, Bon Hooghly, BT Road, Kolkata, India
Corresponding Author :	Ashish Kumar National Institute for Orthopedically Handicapped Bon Hooghly BT Road, Kolkata-700090, India Tel: +919883199597 E-mail: ashi_225@yahoo.co.in
Received June 25, 2012; Accepted July 18, 2012; Published July 18, 2012

Keywords

Osteoarthritis; Proprioception; Dynamic restraints; Motor control

Introduction

The worldwide increase in the elderly population is the most important change as per the public health statistics for 21st century [1]. It is being estimated that the number of people over the age of 65 will be doubled in the next 20 years [2]. Consequently, osteoarthritis (OA) and similar diseases that are more frequently encountered in advancing years become much more important from both medical and economic aspects [3]. A survey in India in 2007 revealed the OA prevalence rate of 32.6% in rural and 60.3% in urban population. OA was present in 50.2% population falling in age group 65-74 years whereas it was 97.7% in age group 84 years or older [4]. Socioeconomic impact of OA is greater than other diseases due to its higher prevalence [5].

Risk factors of OA [6] can be grouped as

a. Non-modifiable risk factors such as Age (The risk of developing most types of arthritis increases with age), Gender (Most types of arthritis are more common in women; 60% of all people with arthritis are women).

b. Modifiable risk factors such as Overweight and Obesity (Excess weight can contribute to both the onset and progression of knee OA), Joint Injuries (Damage to a joint can contribute to the development of OA in that joint), Infection (Many microbial agents can infect joints and potentially cause the development of various forms of arthritis), Occupation (Certain occupations involving repetitive knee bending and squatting are associated with knee OA).

c. Other possible risk factors such as Estrogen deficiency, Osteoporosis (inversely related to OA), Vitamins C, D and E deficiency – equivocal reports, Elevated levels of C-reactive protein (increased risk with higher levels).

Common signs and symptoms of knee OA include knee pain, tenderness, joint stiffness and decreased muscle strength. In addition, individual with knee OA often exhibit poor neuromuscular control, slower walking speed, decreased functional ability and increased susceptibility to fall [7-10].

Proprioception encompasses the senses of joint position and joint motion. These senses originate from the stimulation of specialized nerve-endings or mechanoreceptors in the joint capsule and ligaments. The receptors convert the mechanical energy of physical deformation into the electrical energy of a nerve action potential and this action potential propagates to the higher center for motor control [11].

Reflex contraction of muscles by stimulation of proprioceptors protects joints from mechanical insults. Conscious contractions are, in most cases too slow to prevent the injury, because their nerve paths are usually longer therefore slower. Proprioception involves different sensory systems of muscles, ligaments, tendons, joints, skin, and organs of vision and balance [9,12,13].

Most of the previous studies on proprioception have focused on young active athletes [14-16] or on recipients of total knee replacements [17-19]. Very few studies have focused on arthritic knees. The purpose of this study was to compare the proprioception deficits in age matched radiologically significant osteoarthritic and non osteoarthritic knee.

There are many ways to measure the proprioception with joint position sense error [20]. We have attempted to measure joint position sense error by a wireless goniometer mediated solely by the patient without any external cue like visual, auditory etc. This is very simple method to measure the joint position error for interpreting the proprioception deficits.

Methodology

Subjects

Fifty six patients were approached with the proposal of the study. Out of which forty four were included. Eight did not fulfill the inclusion criteria and four refused to participate.

Inclusion and Exclusion criteria

Both male and female subjects with a pre diagnosed cases of knee OA of age group 40 to 65 years showing radiographic changes in one or both knee joints were included in the study. Any systemic infection, neurological or; vestibular disorder, deformity of back, hip, knee and ankle, history of either knee trauma during last 3 month or knee surgery, clinically significant Anteroposterior or Mediolateral instability of knee, taken steroid injection within 6 months in knee joint and uncooperative patient were excluded. Aim of the study and procedure were explained and a written informed consent was taken from subjects who agreed to participate.

Ethical approval and patients’ informed consent

The ethical approval was taken from institutional ethical committee, NIOH Kolkata. Informed written consent was taken in the patient’s language.

Instrumentation to measure proprioception

The ability to replicate target knee‐joint angles was assessed using an electronic goniometer (Tracker Freedom Wireless Goniometer). The test subjects were positioned in supine lying and made to wear headphones and dark glasses to eliminate auditory and visual cues from the testing apparatus. They wore shorts to negate any extraneous skin sensation from clothing touching the knee area. An Electrogoniometric scale was fastened to the lateral side of the knee with fixed arm pointing towards greater trochanter of femur, movable arm pointing to lateral malleolus and fulcrum at the joint line (Figure 1). Skin stretch was checked while fastening the arms with adhesive tape. A trial was allowed at each angle before testing. The knee was positioned in full extension. The subject was then asked to flex the knee joint to a pre-determined target angle of 30°, 45° and 60° (Figure 2). Auditory feedback was constantly provided by the therapist during trial. Hold time was 5 seconds at each targeted angle. After returning to the starting position and having remained there for 10 seconds, the subject was asked to flex the knee again to reach the target angle. At every angle (30°, 45°and 60°) three readings were taken, mean was calculated and recorded as the patient’s joint position sense. Although the validity and reliability of position matching tests have rarely been evaluated, it is well accepted that the magnitude of accuracy can be a useful indicator of proprioceptive acuity. Precisely those individuals who are prone to making large position matching errors are thought to be, at least in some way, proprioceptive deficient. This is supported by Torres et al. [21] who stated that the testing protocols for proprioception measurement usually comprise defined target position that is identified and appreciated by the subjects, which are blindfolded. Then, the target position is reproduced passive or actively to the best of subject’s ability.

Results

Demographic data

Forty four patients (19 male and 25 female) were evaluated for the study. Their age (in year), weight (in kilogram), height (in centimeter), and BMI (Kg/m2) was recorded. Table 1 represents the details of the mean and standard deviation of these scores.

Joint Position Sense (JPS) Error

Data for the JPS error was measured at the day before taking any intervention. For both groups data were taken at three predetermined angle at 30°, 45°and 60° respectively. Between group comparison of JPS error is represented in Table 2. In non arthritic subjects the difference measured between the real and the perceived angles of flexion varied from 0.79 to 7.39 whereas in osteoarthritic knees it varied from 6.63 to 12.55. The JPS error was found to be significantly different between two groups at all the preset angles (p < 0.05).

Discussion

Our study has shown that with aging there is some proprioceptive error without any clinical feature as in group B. It is also supported by Stauffer et al. [22] who suggested that proprioceptive diminution with age and might be the major factor for age related gait pattern. This is also in line with the findings of Saxton et al. [23] who stated that elderly subjects tended to overshoot the criterion angle more often than subjects from the young and middle-aged groups. In osteoarthritic knee (group A) this error was more in comparison to non osteoarthritic knee. This error of proprioception might be expected as a result of various mechanisms. Barrett et al. [10] stated that laxity of the capsule and ligaments caused by loss of cartilage and bone height, lytic enzymes released around the joint may damage the receptors end organ within the capsule decreasing proprioception perception. This is also supported by Hurley and Scott DL [24] who reported that in patients with knee OA, articular damage may reduce quadriceps motoneurone excitability, which decreases voluntary quadriceps activation thus contributing to quadriceps weakness and diminishing of proprioceptive acuity. This is corroborated with Diracoglu et al. [8]who reported that balance and strength training brought significant improvement in proprioception reflecting weakness as a factor of diminution of proprioception. But this finding is contradicted by Koralewicz et al. [25] who reported that loss of proprioception might occur prior to the development of the structural changes of arthritis.

From this study it is not possible to conclude whether loss of joint position sense causes osteoarthritis or is a consequence of it. Allum et al. [26,27] reported role of proprioceptive input and emphasized proprioception as an essential component for initiating and modulating postural adjustments. Hence correction of proprioceptive error should be planned as a major deficit and should be included in threatened lower limb.

Conclusion

Our method of measuring proprioception is easily reproducible. Proprioception deteriorates with aging and more deterioration with degenerative disease in elder.

Limitation

Proprioception deficits with grade of knee OA were not studied. Population without radiological changes but with clinical symptoms not studied.

Recommendation for further study

Proprioceptive correction should be thought in elder patients especially with degenerative changes to lower extremity.

References

Clark WAV (2004) The End of World Population Growth in the 21st Century: Implications for Sustainable Communities. 30: 43-60. Adelman AM, Daly MP, Weiss BD (2001) 20 Common Problems in Geriatrics. International ed McGraw-Hill Medical Publishing Division 15-26. Lawrence RC, Helmick CG, Arnett FC, Deyo RA, Felson DT, et al. (1998) Estimates of the prevalence of arthritis and selected musculoskeletal disorders in the United States. Arthritis Rheum 41: 778-799. Sharma MK, Swami HM, Bhatia V, Verma A, Bhatia SPS, et al. (2007) An epidemiologic study of correlates osteoarthritis in geriatric population of UT Chandigarh. Indian journal of community medicine 1: 77-78. Helmick CG, Felson DT, Lawrence RC, Gabriel S, Hirsch R, et al. (2008) Estimates of the prevalence of arthritis and other rheumatic conditions in the United States. Part I. Arthritis Rheum 58: 15-25. Centers for disease control and prevention. Callaghan MJ, Selfe J, McHenry A, Oldham JA (2008) Effects of patellar taping on knee joint proprioception in patients with patellofemoral pain syndrome. Man Ther 13: 192-199. Diracoglu D, Aydin R, Baskent A, Celik A (2005) Effects of kinesthesia and balance exercises in knee osteoarthritis. J Clin Rheumatol 11: 303-310. Kisner C, Colby LA (2003) Resistance exercise In: Therapeutic Exercise, Foundations and Techniques, 4th ed. Jay Pee publishers 58-148. Barrett DS, Cobb AG, Bentley G (1991) Joint proprioception in normal, osteoarthritic and replaced knees. J Bone Joint Surg Br 73: 53-56. Gardner EP, Martin JH (2000) Coding of sensory information. In: Kandel ER, Schwartz JH, Jessell TM, editors. Principles of Neuroscience. 4th ed New York, NY: McGraw-Hill 411- 428. Bryan LRN, Lephart SM (2002) The Sensorimotor System, Part II: The Role of Proprioception in Motor Control and Functional Joint Stability. J Athl Train 37: 80-84. Johansson H (1991) Role of knee ligaments in proprioception and regulation of muscle stiffness. J Electromyography Kinesiol 1: 158-179. Barrack RL, Skinner HB, Brunet ME, Haddad RJ (1983) Functional performance of the knee after intraarticular anesthesia. Am J Sports Med 11: 258-261. Barrack RL, Skinner HB, Brunet ME, Cook SD (1984) Joint kinesthesia in the highly trained knee. J Sports Med Phys Fitness 24: 18-20. Goodwin GM, McCloskey DI, Matthews PB (1972) The persistence of appreciable kinesthesia after paralyzing joint afferents but preserving muscle afferents. Brain Res 37: 326-329. Barrack RL, Skinner HB, Cook SD, Haddad RJ (1983) Effect of articular disease and total knee arthroplasty on knee joint position sense. J Neurophysiol 50: 684-687. Cash RM, Gonzalez MH, Garst J, Barmada R, Stern SH (1996) Proprioception after arthroplasty: role of the posterior cruciate ligament. Clin Orthop Relat Res 331: 172-178. Schultz RA, Miller DC, Kerr CS, Micheli L (1984) Mechanoreceptors in human cruciate ligaments. A histological study. J Bone Joint Surg 66: 1072-1076. Grob KR, Kuster MS, Higgins SA, Lloyd DG, Yata H (2002) Lack of correlation between different measurements of proprioception in the knee. J Bone Joint Surg Br 84: 614-618. Torres R, Vasques J, Duarte JA, Cabri JM (2010) Knee proprioception after exercise-induced muscle damage. Int J Sports Med 31: 410-415. Stauffer RN, Chao EYS, Gyory AN (1977) Biomechanical gait analysis of the diseased knee joint. Clin Orthop relat Res 126: 246-255. Saxton BJE, Wong WJ, Hogan N (2001) The influence of age on weight-bearing joint reposition sense of the knee. Exp Brain Res 136: 400-406. Hurley MV, Scott DL (1998) Improvement in Quadriceps sensorimotor function and disability of patient with knee osteoarthritis following a clinically practicable exercise regimen. Rheumatology 37: 1181-1187. Koralewicz LM, Engh GA (2000) Comparison of Proprioception in Arthritic and Age-Matched Normal Knees. J Bone Joint Surg Am 82: 1582-1588. Allum JHJ, Honegger F, Acuna H (1995) Differential control of leg and trunk muscle activity by vestibulo-spinal and proprioceptive signals during human balance corrections. Acta Otolaryngology 115: 124-129. Allum JHJ, Bronstein AM, Brandt TH, Woollacott M (1996) Vestibulospinal and proprioceptive reflex assessment of balance control. Clinical disorders of balance posture and gait. Arnold, Londan.

The Key in the Initial Success of Chronic Pain Treatment

Fernando Itza Santos*

Pelvic Pain Center, Madrid, Spain

Yoga is a physical and mental practice with origins dating back to more than 5000 years in India. This discipline strives to obtain an internal state of peace [1]. Apart from the spiritual goals, the physical postures or asanas of yoga can help to diminish anxiety and assist with helping the body to become more flexible. Yoga could be utilized as a physical therapy intervention as well as a total body conditioning/ training program. We believe in the benefits of yoga so completely that we recommend this kind of “special” exercise to all of our patients suffering from chronic pelvic pain.

Physiotherapy (PT) is a health care career that incorporates the therapeutic use of physical agents or modalities, such as massage, ultrasound and exercises to name a few. In 1958, the World Health Organization (WHO) defined physical therapy as: "The science of treatment through: physical means, therapeutic exercise, massage and electrotherapy. Moreover, PT involves performing various physical examination tests including muscle strength tests and joint range of motion, to determine functional capabilities. Other tests including vital capacity measurements as well as special selective tissue tension tests are used as a comprehensive method to come up with a clinical diagnosis. For our practice, the discipline of PT provides a complimentary addition, creating a synergy between physiotherapy and medical treatments that together work to benefit our patients who are seeking pain relief.

Both medicine and PT work together to acheive the same end, that is to relieve the chronic pain in the patients we see who are suffering from various conditions.

When looking at the discipline of Yoga, it is immediately evident that Yoga and PT share a common feature: the stretching. Stretching refers to the practice of gentle exercises designed to help prepare the muscles for greater effort and to increase the range of motion in the joints. During stretching, muscles are lengthened beyond their rest position and this turns out to be beneficial to a healthy body. The benefits of stretching for patients with pelvic pain include: increasing joint range of motion; increasing flexibility of the groin muscles, tendons, fascia, ligaments, joint capsules and skin. Stretching can also help to avoid common sports injuries by improving the coordination of agonistantagonist muscles and preventing muscle stiffness after exercise. All of the above mentioned benefits have been previously documented by other authors [2,3]. In the paper by Weerapong et al. [2] a reduction in anxiety, relaxation and an improvement in mood state was reported. These same benefits of stretching are therefore likely expected when it comes to helping athletes, by enhancing their performance and reducing injury risk.

Cunha et al. [3], compared the effect of conventional static stretching and muscle chain stretching ((upper trapezius, levator scapulae, suboccipitalis, erector spinae, gluteus maximus, ischiotibials, triceps surae, and foot intrinsic muscles) in female patients suffering chronic neck pain. These authors showed that conventional stretching and muscle chain stretching, in association with manual therapy, were equally effective in reducing pain, improving the range of motion, and quality of life for the study participants.

Another common characteristic between Yoga and PT is relaxation. The act of relaxation induces a release of muscle tension and a return to equilibrium. Pain is worsened by stress, and stress could be magnified by psychological anxiety. Stretching can induce a state of mental relaxation and as such could help decrease pain perception as well as assist in various other heightened mental states such as helping the body better cope with sequla associated with trauma. Hypercortisolemia (excessive levels of the stress hormone cortisol), is well-known to occur in depression and stress. A study [4] was done showing that Yoga practice proved useful as a means to reduce the parameters of stress, including actual lowered blood levels of cortisol. This study divided subjects into three groups (yoga alone, yoga along with antidepressant medication and antidepressant medication alone). The study was conducted at a tertiary care psychiatry hospital. A validated yoga module was used as therapy taught over a month and included at home daily practice. 54 out-patients suffering from clinical depression were rated on the Hamilton Depression Rating Scale. These subjects also had their serum cortisol measurements taken at baseline and after 3 months of yoga practice. The findings of this study supported that yoga may act at the level of the hypothalamus by its 'anti-stress' effects (shown as a reduction in cortisol), to bring about relief from depression.

Another common aspect between Yoga and PT is pain desensitization. Desensitization is a method used to decrease or remove a noxious pain stimulus. In PT pain desensitization may be achieved by edema control, desensitization specific techniques, and functional training. Pain desensitization would be the application of repeated sensory stimuli that produces no pain or discomfort, but may be unpleasant in a hypersensitive area. The elements used for desensitization depend on the involved area and consist of various textures, pressure, vibration, and heat or cold.

Desensitization follows a progressive method of gradual introduction of various stimulus applied to the hypersensitive region. The sensory stimulus ranges from low to high displeasure and may include: silk, cotton, rugged or rough textures. The progression may take many days or weeks according to sensory disturbance levels. Desensitization can minimize pain response to various stimuli. However, the affected area may not tolerate contact with a particular stimulus. The goal of desensitization is to inhibit or interrupt the perception of the previously uncomfortable stimulus as painful. This does not ensure that this stimulus is now going to be perceived as pleasant or enjoyable, but, the response given will no longer be perceived as extremely painful. This effect was demonstrated in a randomized clinical trial by Whitehurst and colleagues [5]. In their study, these authors reported the following data: a total of 402 patients were randomly assigned to a brief pain management program (BPM) or PT. The PT program was designed to be consistent with best current manual physiotherapy practice in the UK. Treatment approaches were standardized, with emphasis on diagnosing and treating biomechanical dysfunction of the spine with manual therapy techniques (including mobilization, manipulation, or other soft-tissue treatment approaches) and back-specific exercises coupled with ergonomic advice. They adopted a health care perspective, examining the direct health care costs of low back pain. Outcome measures were quality-adjusted life years and 12-month change scores on the Roland and Morris disability questionnaire. Whitehurst and colleagues [5] concluded that PT is a cost-effective primary care management strategy for low back pain. However, the absence of a clinically superior treatment program raises the possibility that BPM could provide an additional primary care approach, administered in fewer sessions, allowing patient and doctor preferences to be considered.

While both PT interventions and Yoga stretch muscles, soft tissue, and increases the range of motion in joints, Yoga practice includes the philosophy of taking care of your body, and teaches one how to take charge of their experience even when one is in pain. These claims are supported in a study by Williams and colleagues [6]. These authors utilized Iyengar yoga (which is a form of Yoga that not only emphasizes asanas, but also mental discipline and holistic health) as an intervention to address back pain. Patients receiving yoga showed significant reductions in pain and functional disability, compared to the controls, after 3months follow-up.

From another point of view, we can see the relationship between Yoga and PT in helping to assist with sleep. Yoga may aid the treatment of insomnia through relaxing physical exercises and techniques of breathing thereby promoting regular sleep without having to take medicine to induce sleep. Medicine can interfere with the natural sleep cycle of the body and have side effects. Those who have difficulty falling asleep or staying asleep can try yoga sequences of deep relaxation and meditation, for example: lying down for half an hour before bedtime to promote a pleasant dream. The causes of insomnia can be removed by the continuous practices of yoga. To support these claims, we found in medical literature, a randomized clinical controlled trial by Hariprasad et al. [7]. Hariprasad and colleagues reported the following data: a total of 120 subjects from nine nursing homes were randomized in to yoga group (n=62) and waitlist group (n=58). Subjects in the yoga group were given yoga intervention daily for 1 month and weekly for 3 months. Subjects were encouraged to practice yoga without supervision for 6 months. Subjects in the waitlist group received no intervention during this period. Subjects were evaluated with World Health Organization Quality of Life questionnaire and Pittsburgh Sleep Quality Index at baseline and after 6 months. The authors concluded that Yoga improves the quality of life and sleep quality of these patients living in retirement homes.

PT may contribute to help with insomnia, through hydrotherapy, electrotherapy or lymphatic drainage, etc, constituting an "ideal" method of relaxation, especially when applied to the face, head and neck. Sleep disturbance is a very common clinical symptom in patients with chronic pain, related to physical inactivity and depression. To support these claims, we have found in medical literature a randomized clinical controlled trial; Eadie et al. [8] reported a paper with the following data: 20 participants with chronic low back pain were randomly assigned to a walking program, supervised exercise, or usual physiotherapy (advice, manual therapy, and exercise). Sleep was assessed by Pittsburgh Sleep Quality Index, Insomnia Severity Index and Pittsburgh Sleep Diary. The authors determined the effectiveness of physiotherapy for sleep disturbance in chronic low back pain.

In conclusion, in our practice if we have any patient suffering from chronic pain, we recommend that they should initially fulfill three conditions to alleviate their chronic pain: stretching of the body muscles, to sleep as well as possible, and to maintain a stress free mind. All of this is possible to obtain in some measure through Yoga, PT and traditional medicine all working together.

References

Riley D (2004) Hatha yoga and the treatment of illness. Altern Ther Health Med 10: 20–21. Weerapong, Pornratshanee; Hume, Patria A. and Kolt, Gregory S (2004) Stretching: Mechanisms and Benefits for Sports Performance and Injury Prevention. Physical Therapy Reviews 9: 189–206. Cunha AC, Burke TN, França FJ, Marques AP (2008) Effect of global posture reeducation and of static stretching on pain, range of motion, and quality of life in women with chronic neck pain: a randomized clinical trial. Clinics 63: 763-770 Thirthalli J, Naveen GH, Rao MG, Varambally S, Christopher R, et al. (2013) Cortisol and antidepressant effects of yoga. Indian J Psychiatry 55: 405-408. Whitehurst DG, Lewis M, Yao GL, Bryan S, Raftery JP, et al. (2007) A brief pain management program compared with physical therapy for low back pain: results from an economic analysis alongside a randomized clinical trial. Arthritis Rheum 57: 466-473. Williams KA, Abildso C, Steinberg L, Doyle EJ, Epstein B, et al. (2009) Evaluation of the effectiveness and efficacy of iyengar yoga therapy on chronic low back pain. Spine 34: 2066–2076. Hariprasad VR, Sivakumar PT, Koparde V, Varambally S, Thirthalli J, et al. (2013) Effects of yoga intervention on sleep and quality-of-life in elderly: A randomized controlled trial. Indian J Psychiatry 55: 364-368. Eadie J, van de Water AT, Lonsdale C, Tully MA, van Mechelen W, et al. (2013) Physiotherapy for sleep disturbance in people with chronic low back pain: results of a feasibility randomized controlled trial. Arch Phys Med Rehabil 94: 2083-2092.

Yoga for Rheumatic Conditions: Potential Physical, Cognitive and Affective Advantages

Matthew C Sullivan BA, Elena Manning BS and Raveendhara R Bannuru*

Center for Treatment Comparison and Integrative Analysis, Division of Rheumatology, Tufts Medical Center, Boston, MA, USA Keywords Yoga for rheumatic conditions; Potential physical; Cognitive and affective advantages Musculoskeletal diseases, including conditions such as osteoarthritis, rheumatoid arthritis, and fibromyalgia, are among the leading causes of pain and disability worldwide, with an estimated global prevalence of 810 million in 2010 [1]. In 2005, it was estimated that nearly 27 million US adults have clinical osteoarthritis (OA), a number which is likely to increase significantly in the next 20 years as the proportion of adults over 65 years of age rises [2]. Arthritis and other rheumatic conditions represent the most common cause of disability in the US [3]. Most of these rheumatic conditions do not have effective disease modifying treatments; furthermore, commonly used pharmacological treatments are expensive and are associated with significant adverse events [4]. These chronic, debilitating conditions can also alter psychological well-being in affected individuals. Thus, rheumatic conditions pose a major public health concern. Physical exercise interventions that build strength, increase range of motion, and provide aerobic activity have been widely studied and supported for the maintenance treatment of disabling rheumatic conditions [4,5]. These interventions include a broad range of regimens with varying practical benefits [6]. As with conventional exercise interventions, yoga has been found to have significant benefits for reducing chronic pain and related disability [7]. Studies conducted in individuals with OA, fibromyalgia, and rheumatoid arthritis (RA), also suggest efficacy among rheumatic populations (Table 1). Yoga interventions in western complementary medicine are distinct from other modes of physical activity due to their composite mental and physical components. Although variations exist among yoga interventions, yoga typically consists of a combination of physical postures, breathing techniques, and a state of concentration on the moment-to-moment present, otherwise known as mindfulness. As with other forms of physical exercise, yoga—in particular the “asana” body positioning component-has been found to increase physical flexibility, balance, and strength [8]. However, in addition to these suggested functional benefits, the breathing and meditation components of yoga may also help to increase awareness and decrease stress [9]. Mindfulness-the increased awareness of one’s emotions and pain symptoms-is the goal of numerouspsychotherapeutic and mind-body interventions for chronic pain. Such approaches aim to increase acceptance of-and habituation to-pain, in order to reduce unsuccessful attempts to control or avoid the pain [10]. Applied in chronic pain management, mindfulness-based techniques have been found to be associated with significantly decreased pain symptoms and increased emotional and physical functioning, both in OA and in other chronic pain conditions [11,12]. Furthermore, yoga has been found to be associated with improvements in autonomic regulation, including decreases in anxiety and blood pressure, and improved metabolic regulation [13]. Given that individuals with OA and RA often suffer from co-morbid depression and anxiety symptoms, a physically active regimen that also provides cognitive and emotional benefits may be especially effective for reducing disability and improving quality of life in such individuals [14,15]. In a recent meta-analysis of yoga for depression, yoga was found to significantly reduce depressive symptoms relative to control interventions [16]. Furthermore, for individuals with fibromyalgia, yoga was found to reduce pain symptoms, increase mindfulness, and decrease cortisol levels in a recent prospective cohort study [17]. Considering the potential of yoga interventions to increase physical functioning and decrease cognitive, affective, and autonomic symptoms in this large clinical population, future research should be directed at determining the efficacy and feasibility of yoga interventions in rheumatic individuals with co-morbid clinical depression and anxiety. Because patient attitudes regarding yoga are not fully understood among patients with rheumatism, patient interest in yoga practices should also be investigated in this clinical subpopulation. Although exercise interventions can confer significant benefits for arthritisrelated pain and disability, noncompliance may hamper the potential effectiveness of such treatments. Previous research has indicated that yoga is commonly used among patients with rheumatic diseases; the 2002 National Health Interview Survey found that such patients were 1.56 times more likely to have engaged in yoga in the past year than the general population [18]. Since studies of yoga have suggested potential benefits for rheumatic disorders, this practice may have particularly strong appeal if it is found to be preferentially capable of eliciting and maintaining patient adherence [12,19]. Considering the increased rate of yoga use among those with rheumatic conditions, in addition to its potential somatic, autonomic, and emotional health benefits, further research is warranted in this clinical population to substantiate these preliminary findings. Though this alternative treatment regimen may not be suited for all individuals with rheumatic disorders, yoga’s distinctive mindfulness component may hold particular value for certain subgroups of rheumatic patients, including clinically depressed or anxious individuals. Because the current evidence supporting yoga for rheumatic conditions relies largely on the findings of small trials of poor methodological quality, future research should strive to replicate preliminary findings in larger, well-randomized trials [19]. These trials should aim to identify clinical subpopulations that may be particularly likely to maintain yoga and benefit from its meditational components. Furthermore, contemporary yoga practices may need to be adapted to fit the specific needs of the predominately elderly individuals who suffer from rheumatic diseases such as osteoarthritis. Most rheumatic conditions lack effective disease modifying treatments, and commonly used treatment alternatives are associated with considerable safety concerns. This poses a major challenge in treating the many individuals with rheumatic conditions in addition to co-morbid physical and psychological health conditions. Given the interrelated mechanical and psychological components of chronic musculoskeletal pain, yoga may serve as a valuable adjunctive therapy for improving physical function, mental wellness, and overall quality of life among individuals with rheumatic disease. References Vos T, Flaxman AD, Naghavi M, Lozano R, Michaud C, et al. (2012) Years lived with disability (YLDs) for 1160 sequelae of 289 diseases and injuries 1990-2010: a systematic analysis for the Global Burden of Disease Study 2010. Lancet 380: 2163-2196. Lawrence RC, Felson DT, Helmick CG, Arnold LM, Choi H, et al. (2008) Estimates of the prevalence of arthritis and other rheumatic conditions in the United States. Part II. Arthritis Rheum 58: 26-35. Hootman JM, Helmick CG (2006) Projections of US prevalence of arthritis and associated activity limitations. Arthritis Rheum 54: 226-229. Zhang W, Nuki G, Moskowitz RW, Abramson S, Altman RD, et al. (2010) OARSI recommendations for the management of hip and knee osteoarthritis: part III: Changes in evidence following systematic cumulative update of research published through January 2009. Osteoarthritis Cartilage 18: 476-499. Forestier R, André-Vert J, Guillez P, Coudeyre E, Lefevre-Colau MM, et al. (2009) Non-drug treatment (excluding surgery) in rheumatoid arthritis: clinical practice guidelines. Joint Bone Spine 76: 691-698. 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(2010) Mindfulness-based stress reduction for chronic pain conditions: variation in treatment outcomes and role of home meditation practice. J Psychosom Res 68: 29-36. Ebnezar J, Nagarathna R, Yogitha B, Nagendra HR (2012) Effects of an integrated approach of hatha yoga therapy on functional disability, pain, and flexibility in osteoarthritis of the knee joint: a randomized controlled study. J Altern Complement Med 18: 463-472. Yang K (2007) A review of yoga programs for four leading risk factors of chronic diseases. Evid Based Complement Alternat Med 4: 487-491. Shih M, Hootman JM, Strine TW, Chapman DP, Brady TJ (2006) Serious psychological distress in U.S. adults with arthritis. J Gen Intern Med 21: 1160-1166. Matcham F, Rayner L, Steer S, Hotopf M (2013) The prevalence of depression in rheumatoid arthritis: a systematic review and meta-analysis. Rheumatology (Oxford) 52: 2136-2148. 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New Perspective: Outcome Measurement Indices for Yoga Therapy

Paul S Sung*

Departments of Bioengineering and Orthopaedic Surgery, University of Toledo, USA

Low back pain (LBP) is among the most common musculoskeletal symptoms [1]. The reported lifetime prevalence of pain and associated disability ranges from 54% to more than 80%, and the point prevalence rate is around 20% in the general population [2]. Although the burden of LBP is not clearly reported, more effective interventions including yoga therapy could potentially lead to cost savings.

Yoga therapy has been shown as an effective intervention for treating chronic or recurrent LBP [3-5]. Yoga practice may increase muscle strength, endurance, proprioception, and balance while emphasizing movement through a full range of motion (ROM) to increase flexibility and mobility [6]. For example, the rhythmic intervals of breath retention during yoga therapy could help rhythmic intervals of lumbar stability. The kinetics causing intra-abdominal pressure gradients may proceed independent of conscious, neuromuscular control [7]. However, previous studies on yoga therapy mostly utilized pain/disability questionnaires or quality of life tools to compare the limited effectiveness following the intervention [3-6].

An exercise program intended to be a regime of treatment for LBP is usually designed to improve function at the impairment level, such as pain and limited ROM, by improving muscular strength, muscular endurance, trunk flexibility, and/or cardiovascular endurance [8]. Therefore, postural control in subjects with chronic LBP might require objective measurements on complex processes involving integrated motor function for impaired balance performance [9,10].

It has been reported that subjects with LBP demonstrate aberrant motion during dynamic movements [11-14]. The co-ordination of trunk mobility during functional movements depends on flexibility and stability with optimal spinal ROM. More importantly, core muscle strengthening for spinal stability would be critical through yoga therapy. In addition, the functional approaches to treatment may provide a practical approach to the LBP problem [4,15,16].

Although wide ranges of exercise intervention have been developed and many are currently in use [3,16,17], there is conflicting evidence concerning the effectiveness of specific exercises for specific conditions. None of the available exercise interventions has emerged as the most commonly accepted treatment approach of choice for LBP. This problem may not be entirely the result of ambiguity of the effectiveness of the methods, but could be at least partially due to a lack of an outcome measure that serves as a meaningful, commonly accepted gold standard by which to compare the effectiveness of the various methods.

A recent study indicated that yoga intervention decreases functional disability, pain intensity, and depression at the 6-month follow-up in subjects with LBP [4]. Another study indicated that yoga yields an incremental cost-effectiveness intervention for treating subjects with chronic and recurrent LBP [3]. However, there is a lack of evidence regarding the effect of kinematic changes in trunk stability and/or flexibility following yoga intervention.

In this regard, our motion analysis lab developed an objective tool to evaluate comprehensive postural sway during the one-leg standing test [18-21]. The measurements of relative holding time (RHT) and relative standstill time (RST) during one-leg standing might be good postural measurement tools for yoga therapy intervention. These measurements were able to determine balance performance since subjects stand on one leg with the contra lateral hip flexed 90 degrees to maintain body stability [18,20,21].

The RHT was defined as the ratio between the successful holding time and the requested holding time. The subjects were instructed to stand on one leg for 25 seconds (requested holding time); if they stood for 25 seconds (successful holding time), then the ratio was calculated as 1. Therefore, the successful holding time was indicated as the total holding time until the subject failed to maintain stability during the holding test protocol.

The RST was defined as the ratio between the sum of standstill time and successful holding time. The standstill time was measured within the threshold from the postural fluctuation on the force plate. This standstill time was the summation of the tested axis on the force plate that goes below threshold (5 degrees). Therefore, the RST represents the duration when the foot was in a static position on the force plate [18,20,21]. In this way, a comprehensive evaluation of postural balancecould be compared based on normalized kinetic indices during one leg standing following the yoga therapy.

Furthermore, it is also evident that the kinematic changes for the stability of the lumbar spine relative to the core spine could be affected in subjects with LBP who exhibit proprioceptive deficits [22,23]. In our previous studies, the core spine was the direct upward perpendicular line from the pelvic plane of the second sacrum level [18,20,21]. The pelvic plane included both sides of the anterior superior iliac spine and the second sacrum level. Therefore, the lumbar spine motion, which was affected by the pelvis and thorax, may be evaluated more accurately by three-dimensional relative motion from the core spine. Both holding time and kinematic changes from the core spine measurement would be a comprehensive objective tool since postural evaluation requires a process involving integrated motor function for impaired balance performance in subjects with LBP [18-21].

A trunk muscle imbalance may also contribute to unbalanced postural activity, which could prompt a decreased, uncoordinated bracing effect in subjects with LBP. As a result, possible kinematic rehabilitation training such as yoe prevention of falls in such subjects. Yoga is important to enhance both biomechanical and neuromuscular ga intervention could be used in thdifferences in subjects with LBP. Further investigation is required to evaluate stability and functional mobility of the spine following the intervention.

Yoga intervention has been regarded as safe with no adverse events as well as clinically significant improvements in functional disability and present pain intensity in LBP subjects compared to control subjects [4]. Therefore, the increased muscle strength, proprioception, and balance following the intervention could be objectively measured by the single leg standing test for kinetic as well as kinematic changes. It was expected that some variability exists; however, the kinematic changes suggest coordination of postural adjustability, which is the composite output of proprioceptive feedback. As a result, proprioceptive feedback training might be beneficial since postural sway has been associated with low back symptoms [24].

The LBP attributed to spinal disorders directly affects postural stability and balance deficits for detecting impairment [18]. Therefore, specific and customized exercise programs, such as yoga therapy are required for subjects with LBP for balance performance. In order to maintain postural stability components within a certain ROM during single leg standing, the body requires not only reliable sensory feedback or muscle activation from all involved joints, but also the sensitive response of proprioceptive receptors to environmental changes.

Yoga exercise intervention and outcome assessment should be integrated into functional tasks for pain reduction and flexibility in subjects with LBP. In this regard, clinicians should consider outcome measurements with single leg standing tests for postural sway which help prevent further injury by limiting an individual's response rate to external perturbations. This objective outcome measurement could be beneficial to quantify objective progress from yoga therapy for subjects with LBP.

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