The Effect of Somatic Dysfunction of the Pelvis, Sacrum and Lower Lumbar Spine on Weight Bearing
The Effect of Somatic Dysfunction of the Pelvis, Sacrum and Lower Lumbar Spine on Weight Bearing
The study aims to determine if somatic dysfunctions of the pelvis, sacrum and lower lumbar
 spine have an effect on weight bearing. Our subjects are young, healthy subjects without
 recent soft tissue or osseous injury, a less than predetermined leg length discrepancy or
 OMM/chiropractic treatment. Their leg lengths will be measured; weight-bearing will be
 measured using a specialized scale and somatic dysfunctions diagnosed to determine if any
 correlation exists.
Most sources claim that in individuals with leg length discrepancies, they tend to place more
 weight through the shorter lower extremity.1,2 Few cases state that the opposite is true.3
 Many health care practitioners diagnose leg length discrepancies. Osteopathic physicians who
 practice with Osteopathic Manipulative Medicine (OMM) will also diagnose leg length
 discrepancies. They use testing to evaluate whether a leg length discrepancy is structural or
 functional. A structural leg length discrepancy is associated with shortening of bony
 structures.4 The structures affected can be due to congenital defects, which result in
 possible structural shortening of the tibia or femur, slipped capital femoral epiphyses
 (SCFE), or congenital dislocation. Other causes of structural leg length discrepancies
 include post total hip replacement, infections, tumors, paralysis, and trauma, including
 fractures where the gross length of a limb is altered.4 A structural leg length discrepancy
 can be most accurately assessed by physically measuring the distance between the anterior
 superior iliac spine (ASIS) and medial malleolus.4 The most reliable method of diagnosing a
 structural short leg is through full body radiographs. 6 A functional leg length discrepancy
 is a result of altered mechanics of the lower extremities. It is thought that a functional
 short leg occurs secondarily to a rotated pelvis caused by joint contractures and/or axial
 misalignments, including scoliosis.4 In osteopathic literature; functional leg length
 discrepancies are also thought to be the result of altered positions of the pelvis and
 sacrum. It is also thought in osteopathic philosophy that the position of the fifth lumbar
 vertebra affects the position of the sacrum. Therefore dysfunction of L5 will change the
 position of the sacrum such that a functional short leg is created.2(p.780-782) A common
 cause of functional leg length discrepancies diagnosed by osteopathic physicians is that of
 sacral base unleveling.5 The way in which a leg length discrepancy causes unleveling of the
 sacrum is through the femoral head of the longer leg driving the pelvis into a posterior
 rotation via forces placed through acetabular contact. Then the pelvis will typically rotate
 forward in attempts to lengthen the shorter leg, causing the sacral base to become unlevel.5
 In addition, the sacral base tilts toward the side of the short leg.6 Standing postural
 x-rays, which outline sacral declination, are often used by chiropractors and osteopathic
 physicians to diagnose functional leg length discrepancies.6 Another way that functional leg
 length discrepancies are confirmed is through the supine to long sitting test, which tests
 for the presence of innominate rotations that may affect leg length as the cause.

 There is no research known to support the presence of somatic dysfunctions, leg length
 discrepancies and altered weight bearing through lower extremities secondary to this.

 It is common practice among osteopathic physicians who utilize OMM to diagnose
 musculoskeletal somatic dysfunctions of the pelvis, sacrum and lumbar spine. All these
 findings can contribute to low back pain. Therefore, it is the common practice of these
 physicians to diagnose leg length discrepancies, as it may ultimately result in low back
 pain.

 Somatic dysfunction in osteopathic nomenclature is defined as 'impaired or altered function
 of related components of the somatic (body framework) system: Skeletal, arthrodial and
 Myofascial structures, and related vascular, lymphatic and neural elements'.2

 There are specific somatic dysfunctions that lead to leg length differences. These effects
 include the sacral base tilting toward the side of the short leg, a low iliac crest on the
 short leg side, a forward rotation of the innominate on the shorter side and/or a posterior
 rotation of the innominate on the side of the longer leg as a compensatory measure. The
 lumbar spine will develop a convexity toward the side of the short leg.6 Their definitions
 are as follows:

 Anteriorly rotated innominate: Entire innominate appears to be rotated anterior in relation
 to the opposite innominate. The ASIS will be more inferior or caudad and PSIS will be more
 superior or cephalad.2(776-778), 6 Posteriorly rotated innominate: Entire innominate appears
 to be rotated posterior in relation to the opposite hip bone. The ASIS will be more superior
 or cephalad and the PSIS more inferior or caudad.2(776-778), 6 Superior shear of the
 innominate: ASIS, PSIS and pubic ramus is more superior or cephalad than the opposite
 side.2(776-778), 6 Inferior shear of the innominate: ASIS, PSIS and pubic ramus is more
 inferior or caudad than the opposite side.2(776-778), 6

 The way that osteopathic physicians determine the side of the somatic dysfunction is through
 the ASIS compression test. This is defined as follows:

 ASIS compression test: Test for lateralization of somatic dysfunction of the sacrum,
 innominate or pubic symphysis. A posterior compression normally produces a palpatory sense of
 'give' or 'resilience' as the innominate glides slightly posterior at the sacroiliac joint on
 that side. Somatic dysfunction of the pelvis on the side of compression produces resistance
 to the test determining the side of lateralization which is analogous to the determining the
 dysfunctional side. This is interpreted as a positive ASIS compression test.2(777)
 Individuals who have suffered from any type of osseous or soft tissue traumatic injuries in
 the last three months do not make suitable subjects for an evaluation of somatic
 dysfunctions' effects on weight bearing. Neither do individuals who have suffered from any
 type of osseous or soft tissue injuries in the lower extremity joints (knee, ankle, hip) in
 the last twelve months. As stated earlier, leg length discrepancies may be a result of
 trauma. Individuals who have suffered traumatic injuries within the last three months may
 exhibit antalgic or compensatory postures which may displace weight bearing more through one
 lower extremity than the other.7 This will ensure that the treatment population will be as
 homogenous as possible and will improve reliability of the study.

 Individuals who have suffered lower extremity injuries in the last twelve months may also
 exhibit altered weight bearing distribution through the lower extremities. This may be
 something, depending on the chronicity of the problem, which alters weight bearing for an
 extended period of time which may vary depending on the person.7 Therefore, excluding
 individuals who have suffered lower extremity trauma in the last twelve months will also be
 excluded from the study to allow for more homogenous characteristics of our sample
 population. The time constraints of three and twelve months respectively were deemed as the
 exclusion times purely from anecdotal and clinical experience with lower extremity injury
 from the principal investigator and his colleagues.

 1. White, S.C., Gilchrist, L.A., Wilk, B.E. Asymmetric limb loading with true or simulated
 leg-length differences. Clinical Orthopedics and Related Research, 2004,421,287-292

 2. Ward, R. Foundations for Osteopathic Medicine 2nd Edition. 2003, p. 614-618, 780

 3. McCaw, S.T., Bates, B.T. Biomechanical implications of mild leg length inequality.
 British Journal of Sports Medicine, 1991, 25,10-13

 4. Gurney, B. Review: Leg length discrepancy. Gait and Posture. 2002, 15,195-206

 5. Dott, G.A., Hart, C.L., McKay, C. Predictability of sacral base levelness based on iliac
 crest measurements. JAOA, 1994,4, 383-390.

 6. DiGiovanna, EL. Schiowitz S. An Osteopathic Approach to Diagnosis and Treatment.
 Philadelphia: Lippincott-Raven, 301.

 7. Riegger-Krugh, C & Keysor, J.J. Skeletal malalignments of the lower quarter: Correlated
 and compensatory motions and postures. J. Orthop Sports Phys Ther. 1996;23(2):164-170.
Inclusion Criteria:

 -  Medical students of Nova Southeastern University College of Osteopathic Medicine
 (NSUCOM) ages 18-40.

 Exclusion Criteria:

 -  individuals who have suffered from any type of osseous or soft tissue traumatic
 injuries in the last three months.

 -  individuals who have suffered from any type of osseous or soft tissue injuries in the
 lower extremity joints (knee, ankle, hip) in the last twelve months.

 -  anyone who has received either osteopathic or chiropractic manipulation within two
 weeks prior to taking part in the study.

 -  anyone who has a leg length difference of greater than one-quarter inch.