BACKGROUND

For the period of 1991-2002, Medicare data indicates a 132% increase in LBP patients and a 387% increase in LBP related charges. Also, musculoskeletal pain is a well-documented cause of functional decline and disability in older adults. With 75% of long term care residents and 50% of community dwelling older adults reporting chronic pain (Helme et al. 2001), it is necessary for clinicians and researchers to gain a better understanding of the condition to develop effective intervention strategies. Even with the prevalence of this ailment, very little research has been conducted on people over the age of 65.

Assessing physical function in older adults through performance based measures is a common practice in epidemiology literature. However, this has not necessarily carried over into clinical practice. Through population based studies, researchers have demonstrated that mobility status is predictive of functional decline, mortality, and disability in elderly adults (Guralnik et al. 2000). It is also becoming clear that elders with LBP are at greater risk for functional decline as shown through decreased walking speed and increased chair rise time (Reid et al. 2005). Hicks and colleagues have shown that moderate to severe LBP in the year prior to baseline is clearly associated with functional decline (Hicks et al. 2005). The assessment of physical function in older adults is best performed by a combination of self-report instruments and observed measures of physical function (Reuben et al. 1995). The influence of trunk muscle training on physical performance and psychosocial parameters evaluated by these measures has never been examined.

While many studies have demonstrated an association between LBP and poor function of trunk musculature (abdominals and paraspinals), it is still debated whether the inadequacy in trunk muscles is the cause of or a consequence of LBP, or both. Imaging studies using ultrasound, computed tomography (CT), and magnetic resonance imaging (MRI) have been used to study the degeneration of particular muscles. Most studies have shown a decreased cross-sectional area and increased intramuscular fat infiltration correlating to chronic pain. In fact, the mean fat within the multifidus was 23.6% for patients with LBP and 14.5% for healthy volunteers (Mengiardi et al. 2006). High levels of fat infiltration in the trunk muscles may act to weaken the force of the muscles on the spine, contributing to poor function. Also, previous clinical interventions designed to improve function in older adults have largely been focused on training the lower extremities. However, recent evidence suggests that the trunk muscles play an important role in maintaining balance and mobility in healthy older adults (Hicks, Simonsick et al 2005). Trunk muscle exercise interventions may prevent falls and improve mobility status in older adults.

PRELIMINARY STUDIES

Trunk Muscle Composition as a Predictor of Reduced Functional Capacity (Hicks, Simonsick et al. 2005)

Based on cross-sectional findings, Dr. Hicks and colleagues demonstrated that high intramuscular fat infiltration is associated with lower functional capacity three years after initial analysis. Regardless of back pain status, the average trunk muscle attenuation was positively associated with overall physical performance, particularly balance. Participants with moderate to severe back pain had a greater decline in functionality over time. This work, which won the 2004 Clinical Medicine Research Award from the Gerontological Society of America, indicated that trunk muscle composition is an important, yet overlooked approach to treating persons with low back pain.

Clinical Prediction Rule for Response to a Stabilization Exercise Program in Patients with LBP (Hicks, Fritz et al. 2005)

Dr. Hicks and colleagues developed a clinical prediction rule (CPR) to predict treatment response to a stabilization exercise program for patients with LBP. Predictions are based on clinical variables such as straight leg raise, prone instability test, aberrant lumbar motions, existence of any lumbar hypermobility, and fear avoidance beliefs. The work indicated that the response to a trunk stabilization program can be predicted from the variables collected during a clinical examination. The CPR allows clinicians to develop a program for appropriate patient sub-groups.

DESCRIPTION OF STUDY

Using a randomized controlled experimental design (RCT), 62 community dwelling older adults ages 65-85 years with chronic low back pain (LBP), as defined by LBP of greater than 3 months duration, who have never had spinal surgery and have no prominent pain in sites other than the back, will receive one of two interventions: 1) trunk muscle training (TMT) plus neuromuscular electrical stimulation (NMES) or 2) massage, modalities, and exercises 2 times per week for 12 weeks.  Prior to initiating treatment (baseline), immediately after the last treatment session (12 weeks post baseline), and 3 months later (6 month post-baseline), subjects will be evaluated by a physical therapist using a variety of assessments designed to indicate pain level, mood, coping strategies, and physical ability. Evaluations will also include the use of MRI technology to analyze the level of muscular fatty infiltration as well as rehabilitative ultrasound to determine the cross-sectional area of particular muscles as well as muscle function.

Stages of Study

Baseline Analysis

Prior to entering into the study, each potential subject will be interviewed by phone to determine whether they meet all criteria for inclusion in the study. He or she will have all questions answered regarding the study and be given a detailed description of the study. Should the subject elect to participate, he or she will be mailed a packet of information regarding the study and forms to complete prior to their physical therapy evaluation. If medical red flags are found during the phone interview, the patient's physician will be contacted. If the subject is self-referred, the research team will contact the subject's physician for medical clearance for participation. Subjects will be evaluated by a licensed physical therapist, for a range of characteristics including past medical history, pain and disability, psychosocial and mental state, and self rated health. Additionally, a battery of physical tests will be administered in order to establish the current state of mobility and functionality. Rehabilitative ultrasound and computerized gait analysis will be employed by the physical therapist to determine muscle size and function and objectively evaluate gait. If the subject passes all criteria and is included in the study, the structure of the trunk muscles and amount of fatty infiltration will be documented through a diagnostic MRI administered by radiologist Dr. Philip Chao at MRI Consultants. The subject will then be randomly assigned to one of two treatment groups.

Intervention and Re-Assessment

For both intervention groups, treatment will occur twice a week for the duration of the 12 week program. Analysis of the subjects will occur immediately after the 12 week treatment program and 3 months after treatment ends. The subjects will also be requested to participate in phone interviews at 4 and 5 months after the baseline evaluation.

Contact for Further Information

Please contact Megan Sions, PT, MPT, OCS, the research assistant, who will be conducting the evaluations, with questions at megsions@udel.edu or at (302) 831-8675

References

Caggiano E, Emrey T, Shirley S, Craik RL. Effects of electrical stimulation or voluntary contraction for strengthening the quadriceps femoris muscles in an aged male population. J Orthop Sports Phys Ther. Jul 1994; 20(1): 22-28

Guralnik JM, Ferrucci L, Pieper CF, et al. Lower extremity function and subsequent disability: consistency across studies, predictive models, and value of gait speed alone compared with the short physical performance battery. J Gerontol A Biol Sci Med Sci. Apr 2000; 55(4): M221-231

Harridge SD, Kryger A, Stensgaard A. Knee extensor strength, activation, and size in very elderly people following strength training. Muscle Nerve. Jul 1999;22(7): 831-839

Helme RD, Gibson SJ. The epidemiology of pain in elderly people. Clin Geriatr Med. Aug 2001; 17(3): 417-431, v

Hicks GE, Simonsick EM, Harris TB, et al. Trunk muscle composition as a predictor of reduced functional capacity in the health, aging and body composition study: the moderating role of back pain. J Gerontol A Biol Sci Med Sci. Nov 2005; 60(11): 1420-1424

Hicks GE, Fritz JM, Delitto A, McGill SM. Preliminary development of a clinical prediction rule for determining which patients with low back pain will respond to a stabilization exercise program. Arch Phys Med Rehabil. Sep 2005; 86(9): 1753-1762

Hicks GE, Simonsick EM, Harris TB, et al. Cross sectional associations between trunk muscle composition, back pain, and physical function in the health, aging and body composition study. J Gerontol A Biol Sci Med Sci Jul 2005; 60(7): 882-887

Mengiardi B, Schmid MR, Boos N, et al. Fat content of lumbar paraspinal muscles in patients with chronic low back pain and in asymptomatic volunteers: quantification with MR spectroscopy. Radiology. Sep 2006; 240(3): 786-792

Reid MC, Williams CS, Gill TM. Back pain and decline in lower extremity physical function among community-dwelling older persons. J Gerontol A Biol Sci Med Sci Jun 2005; 60(6): 793-797

Reuben DB, Valle LA, Hays RD, Siu AL. Measuring physical function in community-dwelling older persons: a comparison of self-administered, interviewer-administered, and performance-based measures. J Am Geriatr Soc. Jan 1995; 43(1): 17-23