Vibration Therapy as a Rehabilitation Intervention for Postural Training and Fall Prevention

Overview

The occurrence of distal radius fractures is well known to be a sentinel event as these fractures are associated with 2 to 4 times increased risk of subsequent hip fractures in elderly patients. Studies have shown a significantly increased degree of postural sway in these patients, which is strongly associated with recurrent falls. The latest Cochrane systematic review also shows a lack of evidence on the effectiveness of current rehabilitation interventions. Low-magnitude high-frequency vibration (LMHFV) is a biophysical intervention that provides non-invasive, systemic mechanical stimulation and has been shown to improve muscle strength and balancing abilities in healthy, independent and active elderly women in our previous clinical study. Our animal studies have also shown LMHFV promoting myogenic proliferation and hypertrophy, muscle contractibility, and increased fast-fiber switching to muscle fiber type IIA.Previous rehabilitation studies have used clinical functional performance tests, which lack sensitivity and specificity in predicting impaired postural control. The Biodex Balance System SD consists of a dynamic balance platform interfaced with computer software, which offers objective and reliable tests for postural stability and fall risk. This study is a single-blinded, prospective randomized controlled trial to investigate the effect of 6 months of LMHFV after a distal radius fracture in elderly patients. Patients will be recruited and randomized to control or LMHFV group by envelope drawing of computer-generated random numbers. The intervention group will undergo LMHFV at 35Hz, 0.3g (peak to peak magnitude), displacement of \<0.1mm, 20 min/day, at least 3 days/week for 6 months in community centres. Control group will remain in their habitual life style and no vibration used. Outcome assessments will be performed at baseline 0 days, 6 weeks, 3 months and 6 months. Outcome assessor and statistician will be blinded to group allocation. The primary outcome is the effect of LMHFV on postural stability. The Biodex Balance System SD is used to measure the static and dynamic ability of the subjects to maintain the center of balance. Secondary outcomes are the occurrence of fall for the patients in both groups, the health-related quality of life (SF-36), and Timed Up and Go test for basic mobility skills.

Distal Radius Fractures and Medico-socioeconomic Impact Fractures of the distal radius account for approximately 380,000 fractures in the United States each year and occur in 15% of women older than 50 years of age. These fractures are a particular health concern amongst the elderly, who are at risk of fragility fractures, and are associated with long-term functional impairment, pain and a variety of complications. Over the past 10 years, there has been increased popularity of surgical interventions for the treatment of distal radius fractures, especially with the introduction of volar locking plates in 2000. Current medical costs for distal radius fractures are estimated to exceed USD 535 million each year and projected to rise as the incidence and use of internal fixation increases. The Concept of Impaired Postural Stability and Prevention of Fall The occurrence of distal radius fractures is well known to be a sentinel event as these fractures are associated with 2 to 4 times increased risk of subsequent hip fractures in elderly patients. This is an important concept as it is well established that these patients have an increased risk of falling. Fall prevention is therefore crucial to decrease further morbidity and mortality. Studies have shown a significantly increased degree of postural sway in patients with distal radius fractures, in both anteroposterior and lateral directions, which is strongly characterized in older subjects for recurrent falls. A recent study has also revealed that older adults have significantly impaired postural stability by using objective measurements from computerized instruments. Despite on-going studies on distal radius fractures, the latest Cochrane systematic review shows a lack of evidence on the effectiveness of current rehabilitation interventions. The American Academy of Orthopaedic Surgeons (AAOS) position statement also recommends patients with fragility fractures to undergo evaluation of osteoporosis and treatment to prevent future fractures. Notably, there are no recommendations on the role of balance training or physical conditioning. Consequently, the evaluation and treatment of fall risks have been largely overlooked. Further research that target rehabilitation and treat postural instability after distal radius fracture to reduce fall rates are therefore warranted. Low-magnitude High-Frequency Vibration as a Rehabilitation Intervention to Improve Postural Instability and Prevent Fall Low-magnitude high-frequency vibration (LMHFV) is a biophysical intervention that provides non-invasive, systemic mechanical stimulation and has been shown to improve muscle strength and balancing abilities in healthy, independent and active elderly women in our previous institute's study. Furthermore, our animal studies have also shown the ability of LMHFV to promote myogenic proliferation and hypertrophy, muscle contractibility, and increase fast-fiber switching to muscle fiber type IIA compared with control. Numerous other studies have reported whole body vibration to have positive effects on blood circulation in lower extremities and enhanced muscle performance including muscle strength in the elderly. Previous rehabilitation studies have mainly used clinical functional performance tests, which lack sensitivity and specificity in predicting impaired postural control in osteoporotic patients. Therefore, the use of more objective measures to assess instability and fall risk derived from computerized instruments have been recommended. The Biodex Balance System SD (Biodex Medical Systems Inc, Shirley, NY) consists of a dynamic balance platform interfaced with computer software that provides up to 20° tilt from horizontal in a 360° range of motion. The system offers objective and reliable tests for postural stability and fall risk, which have been shown in multiple studies and in elderly patients. In order to provide effective rehabilitation regimens for our patients, the validation of our interventions using objective outcomes is essential. To our knowledge, this is the first study to use an objective device to assess and validate our rehabilitation tool to prevent falls in patients after a distal radius fracture.