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Spinal mechanics related to foot function Outline Epidemiology of LBP Diagnosis & risk factors LBP in pregnancy Basic spinal function How might the foot affect the lower back? Clinical studies Preliminary research findings... (not included in notes) Treatment Summary Epidemiology
of LBP
Epidemic since WWII Point prevalence in the US: 5.6% (Loney & Stratford, 1999) 60-85% lifetime incidence in Westernised countries Largest grouping of non-fatal injuries in WorkCover(Vic): A$410 million (WorkCover Statistical Report, 1997-1998) After the common cold, problems caused by low back pain are the most frequent cause of lost work days in adults under the age of 45 Proper functioning of the lower back is required for almost all activities of daily living Background
to LBP
Natural history characterised by variability & change Hard to research Diagnosis difficult - 70% cases described as 'non-specific' or 'miscellaneous' (Hart et al., 1995) Bed rest vs. continuing light activity Do 'functional restoration' programs work? (Teasell & Harth, 1996) Diagnosed
by…
Plain X-ray (Will show OA and bone disease, but not soft tissues like lumbar disks and nerves) CT or MRI required for soft tissue imaging Multifidus? ? Bone scan to assess bone activity ? EMG/NCS to determine if spinal condition has caused nerve or spinal damage Risk
factors include:
Increased age (influenced injury, influenced discomfort and symptoms) Smoking Previous hx of LBP Years of employment and seniority
Anthropometry Exposure factors (lifting, bending…) Psychological and psychosocial (stressful life events, job satisfaction…) (Ferguson & Marras, 1997)
Structural
diagnosis
As mentioned, only in 20-30% of cases is a specific anatomical diagnosis made disk herniation Abnormal protrusion - may impinge on nerve roots spinal stenosis 'narrowing' of the VC Spondyloarthrosis Osteoarthritis of the spine
all other cases are termed 'idiopathic' however, there is increasing evidence that faulty foot mechanics may be at least a contributing factor in the development of LBP Spinal
Anatomy
Spinal function
due to the lumbar lordosis, there is a constant anterior shear force at the lumbosacral joint (L5-S1), the most stressed spinal joint posterior facet joints (zygoapophyseal) bear 10-40% of the total load and control spinal motion the sacro-iliac joint is slightly moveable, and is involved in a movement called nutation (latin - 'nodding'), in which the sacrum moves forward and backward with bending of the trunk
How
might the foot be related to the lower back?
Theoretical mechanisms include footwear heel height, inadequate shock absorption, XS foot pronation factors, functional LLD, sagittal plane blockade Footwear heel height Increase plantar pressures (Mandato & Nester, 1999) Increase knee joint compressive forces (Kerrigan et al., 1998) Lead to changes in the lower back? Maybe? Increase in lumbar lordosis? Conflicting research.
Inadequate shock absorption Voloshin & Wosk (1985)
Ogon et al. (1999)
XS foot pronation factors Similar underlying framework:
Forefoot varus Rothbart et al. (1995)
Functional LLD Unilateral excessive foot pronation = functional shortening of limb (Sanner et al., 1981) Primarily clinical folklore Single case study (Blake & Fettig, 1983)
Ability of sagittal plane pivots of the foot to function effectively (Payne & Dananberg, 1997)
FHL & LBP
Discussion
Which factors are more important? Still lack of basic science connecting the foot and the back Difficulty of 'gold standard' clinical trials How to classify and diagnose? Natural hx one of variability & change Pain interpretation Some measures have been shown to have some reliability & validity (Hudson-Cook, 1989, Stratford et al., 1994, Kopec et al., 1995) Treatment
Summary
Importance of lower extremity biomechanics in the development of CLBP Foot orthoses have shown to be successful in a number of studies … but can they then cause harm? Still no clear protocol for Mx 
References
Bird AR & Payne CB. Foot function and low back pain: a review of the literature. The Foot. 9: 175-180 (1999) Minkowsky I & Minkowsky R. The spine, an integral part of the lower extremity. In: Valmassy RL (ed.) Clinical biomechanics of the lower extremities. CV Mosby, St. Louis, Chapter 4 Michaud, TC. Foot orthoses and other forms of conservative foot care. Massachusetts, p. 118 |
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76% of 200 subjects reported back pain
