Influence of Leg Length Discrepancy on the Spinal Shape and Biomechanics in Functional and Idiopathic Scoliosis Patients
Influence of Leg Length Discrepancy on the Spinal Shape and Biomechanics in Functional and Idiopathic Scoliosis Patients
The purposes of this study are to use motion analysis techniques to study the biomechanical
 interactions between the spine and the lower limbs in scoliosis patients with or without leg
 length discrepancy (LLD) during activity; to investigate the effects of correction of LLD:
 using foot orthosis on the functional scoliotic spinal curve and motion during functional
 activity; and to test whether idiopathic scoliosis without LLD can be improved by
 artificially creating a leg length discrepancy with a foot orthosis.
Scoliosis is one of the most common back deformities in children. Idiopathic and functional
 (secondary) scoliosis are arguably the two most common types. The etiology of idiopathic
 scoliosis has been studied in many aspects such as genetic factors, skeletal muscle
 abnormalities, neurological mechanisms, and biomechanical factors, while the common causes of
 secondary or functional scoliosis are leg length inequality and muscle spasm. It is evident
 that biomechanical factors that involve the interactions of the musculoskeletal alignment and
 loading are closely associated with the development of both types of scoliosis.

 Leg length discrepancy (LLD) is defined as a condition in which paired limbs are unequal in
 length. It is now generally accepted that LLD can lead to lumbar scoliosis and it is assumed
 that scoliosis caused by LLD can be removed if LLD is eliminated. However, no study has
 documented the effects of the correction of LLD on the functional scoliotic spinal curve and
 motion during functional activity. Since spinal curve and motion have clear associations with
 leg length inequality, one would wonder whether idiopathic scoliosis without LLD can be
 improved by artificially creating a leg length difference with an orthosis when spine surgery
 is not considered or in a less severe condition. It has been shown that LLD and scoliosis
 have effects on pain, force transmission and performance of motion. Therefore, the
 artificially created leg length difference may have negative effects even though the
 scoliosis is improved. The benefits and disadvantages of using a foot orthosis to create
 artificial LLD in order to relieve idiopathic scoliosis require careful investigation.
 Although the biomechanics of the spine or the lower extremities have been studied separately
 in the literature, the biomechanical interactions between the spine and the lower limbs in
 scoliosis patients with or without LLD and the biomechanical effects of treatments using foot
 orthosis on these patients remain to be studied.

 Using motion analysis techniques, the present study aims:

 1. to study the biomechanical interactions between the spine and the lower limbs in
 scoliosis patients with or without LLD during activity;

 2. to investigate effects of correction of LLD using a foot orthosis on the functional
 scoliotic spinal curve and motion during functional activity; and

 3. to test whether idiopathic scoliosis without LLD can be improved by artificially
 creating a leg length discrepancy with a foot orthosis. The optimal heights of the foot
 orthosis for the later two objectives will also be determined. It is hoped that the
 present study will lead to a better understanding of the mechanical interactions between
 the spine and the lower extremities in functional and idiopathic scoliosis patients, and
 a better treatment for these patients.
Inclusion Criteria:

 -  Functional scoliosis patients who have lumbar scoliosis combined with significant
 structural LLD

 -  Adolescent idiopathic lumbar scoliosis patients without LLD

 Exclusion Criteria:

 -  Do not suit the inclusion criteria