An investigation of the Claims Made about Balance Chairs S Jackson ~
Balance chairs a r e designed with a seat t h a t tilts forwards 15"and has a corresponding backward tilting shin support. Manufacturers claim t h a t these chairs maintain t h e natural posture of t h e spine, remain comfortable, and may benefit people with back pain. A study was designed to compare the benefit of t h e Balans Office Mobile Chair (BMOC) between subjects with back pain (BPI, and with no back pain (NBP) over time. Twenty-four subjects (12 in each group), volunteered to sit on the BMOC. After being shown how to use the chair they sat for a n hour at a n adjustable work surface typing a standardised task on a personal computer.
Measurements were taken every ten minutes over the hour. Lumbar curvature was recorded using moire fringe topography (Djamil, 1992). Muscle activity in the para-spinal muscles was measured a t the level of the first and fifth lumbar vertebrae using a machine designed to record the total amount of muscle activity within a ten-minute period. General comfort w a s d e t e r m i n e d u s i n g a L i k e r t scale a n d lower back discomfort (LBD) was assessed using a visual analogue
scale. Questionnaires providing individual details were also completed. The raw data were plotted for each of the above variables and showed great individual variation w i t h n both groups. The Balans design appeared to maintam a lumbar lordosis for most subjects. Although muscle activity a t both levels was initially g r e a t e r in BP subjects, recordings decreased over time in both BP and NBP groups. General comfort decreased similarly in both groups whereas LBD appeared to increase more i n the BP group than the NBP group. T-teete of the regression coefficients over the hour for each variable confirmed that the only observation which was significantly different between the BP and NBP groups was LBD ( p = 0.04). Qualitative comments from the questionnaires again varied within groups. In spite of the increase in LBD in t h e NBP group, the majority of subjeds in both p u p s commented that the chair was quib comfortable. The BMOC appears to benefit people both with and without back pain in terms of lumbar lordosis without a need for increased muscle activity, but BP subjecta in particular may find it a n uncomfortable experience initially.
ReteFence Djamil. I M (1992). 'A
study d moire topography metrology in medicine' in: Alberti. Derup. Hierholzer (eds) Surface Tq~ogfa$d?y and SPMa) Defomity Vl, Gustav Fischer. SMigaR
An initial study demonstrated t h a t CLBP was t h e commonest muse of referral to disability advisers in the north-west of England. Deepite this no rehabilitation programme existed i n t h e region, specifically designed to help this group find employment. A pilot study was developed by health and employment agencies to inveswate the efficacy of a pain management approach in returning unemployed CLBP patienta to work. Following clinical and psychological assessment P J Watson a group of 22 long-term unemployed pereons (average time unemployed 4.8 years) with CLBP completed a C J Main r e h a b i l i t a t i o n p r o g r a m m e of physiotherapeutic. M Radcliffe psychological and employment related interventions. Return to work following rehabilitation has always The results demonstrated an increased lumbar range been considered a poor indicator of successful treat- of motion ( p < 0.01 t o < 0.001). a r e d u c t i o n i n ment outcome because of t h e variable influence of disability, a s measured on t h e Roland and Morris Disability Questionnaire (Roland and Morris, 1983) occupational strain, management practice and attitudes of individuals to their workplace (Nordin, 1992). ( p < 0.001)and a reduction in fear of activity. measured Evidence from previous s t u d e s has demonstrated that by the Fear Avoidance Beliefs Questionnaire (Waddell the chances of returning to work following a period of et af, 1993) ( p < 0.001).More importantly, a t threeunemployment due to chronic low back pain (CLBP) month follow-up, 50% of those completing the course reduce dramatically with time. ARer two years such a gained employment or workplace training, 23% were described as 'actively s e e k i n g work' by local job person has, statistically, no chance of ever working again (Waddell. 1994). Sickness and invalidity benefit centres, and 4.5% were attending further education. Of the remaining subjects 22.5%described themselves payments for CLBP have risen dramatically in the last 15 y e a r s d e s p i t e n o c o n v i n c i n g e v i d e n c e f o r a n as receiving further treatment or continued to receive sickness benefit. increase in incidence (Waddell, 1994).
An Occupationally Oriented Rehabilitation Scheme for Longterm Unemployed Persons with Chronic Low Back Pain Increases Return to Work
Surface Electromyography in the Identification of Patients with Chronic Low Back Pain and Assessment of Treatment Outcome P J Watson CKBooker
ACNChen C J Main
The role of paraspinal muscle in the generation and maintenance of chronic low back pain (CLBP) remains unclear. Studies have demonstrated both elevated and reduced levels of surface electromyography (sEMG). This conflict of results can be attributed to differences in detinition of CLBP, methods of m r d i n g and interpretation of information. We suggest that static sEMG may not be of sufficient sensitivity but dynamic changes in BEMG can better discriminate t h e CLBP patienta from the controls. Tbe activity of t h e paraspinal muscle in 7 0 CLBP patients and 20 healthy controls was examined using sEMG d u r i n g t h e s t a t i c p o s t u r e s of s i t t i n g a n d standing, and during dynamic activity of forward flexion. The sites examined were at the levels of T10. L2 and L5. The degree of abnormality was operationalised by the construction of a flexion-relaxation index for each of the sites examined. The flexion-relaxation index was developed by analysis of sEMG activity during the forward flexion phase and the activity at the fully flexed position. Absence of the flexion-relaxation reflex was noted in the CLBP group at L2 and W levels, as reported in the literature. The level of activity i n t h e fully flexed phase of forward flexion waa significantly greater in the CLBP group than controls (T10: 10.1 us 6.7, F = 4.62, p < 0.03; J.2: 16.5 us 2.5, f = 18.63, p < O.oooO1; 16.2 us 2.2, f = 20.99, p < o.oooO1). The flexion-relaxation index demonstrated sigrufcant lower values in the CLBP group compared to the healthy controls (L2: 2.69 US 12.44, F = 65.44; W:2.62 US 12.86, F = 75.54; p v d u e s all a t < oooO1). Comparison of the sEMG in t h e static postures demonstrated no differences between t h e groups. The combined discriminant
validity of the flexion-relaxation indices for aU four lumbar paraspinal sites resulted in 92.8% sensitivity and 7 5 9 specificity (F= 14.3, p < 0.0003). We concluded that t h e flexion-relaxation dynamic activity clearly discriminated the CLBP patients from the healthy controls. The change in the sEMG during dynamic activity was then assessed following physic,therapy exercise intervention i n a group of CLBP patients (n = 35). The results demonstrated significant changes in t h e flexion-relaxation indices following treatment (LL2 2.99 pre-treatment 6.53 post-treatment p < 026; RL2 2.59 pre-treatment 5.35 post-treatm e n t p < 0 2 1 ; LL5 2 . 3 3 p r e - t r e a t m e n t 3 . 6 5 post-treatment p < 0.036; RL5 2.64 pre-treatment 3 . a post-treatment p < 0.099). The changes in dynamic a h v i t y did not correlate with changes in pain measured by the short form McGill Pain Questionnaire (Melzack, 1987) ( p < 0.362 - 0.402) or changes in ranges of movement ( p < 0.362 - 0.478). The changes did demonstrate a high correlation with reduction in fear of activity as measures on the Fear Avoidance Questionnaire (Waddell et al, 1993) ( p c 0.011 - 0.013) and changes in the Self Efficacy Beliefs Questionnaire (Nicholas et a l , 1992) ( p < 0.001 0.007). T h e results s u g g e s t t h a t in p a t i e n t s with CLBP changes in neuromuacular abnormality following rehabilitation may be more closely related to changes in fear of activity and self efficacy than in measures such as pain report and range of movement. If substantiated by on-going research these results have implicat i o n s for t h e m a n a g e m e n t of C L B P p a t i e n t s by physiotherapists.
References Melzack. R (1987) 'The short form McGill Pain Questionnaire'. Paw, 30 191-197
Nicholas. M, Wilson, P H and Goyen J (1993) 'Cornpanson of cognitive behavioural group treatment and an alternative nonpsychologicai treatment for chronic low back pain'. Pain, 48. 339-347
Waddell. G , Newton M. Henderson, I, Somerville. D and Man G J (1993) 'A fear avoidance beliefs questtonnaire (FABQ) and the role of fear-avoidance beliefs in chronlc low back pain and disabilrty', Pam, 52, 157-1 68