ANALISI OPTOELETTRONICA DEL RACHIDE E DEL TORACE IN SOGGETTI CON SCOLIOSI IDIOPATICA

OPTOELECTRONIC MOTION ANALYSIS OF SPINE AND THORAX IN SCOLIOSIS Protocol design and application in a pilot-study group Vincenzo Giovanni FERRARA Matr. R09064 The forward bending test according to Adams (AT) and rib hump quantification by scoliometer are common clinical examination techniques in idiopathic scoliosis, although precise data about the change of angular axial rotation in forward bending posture are not available (1). The aims of the present research is to create a motion analysis protocol to investigate the movement of spine and thorax in a sample of adolescent idiopathic scoliosis (AIS) patients during Adams test. Ten patients (5 men, 5 women; age 16,2+2,3) with idiopathic scoliosis with mean Cobb-angles (19°+2,11°) were recruited. We recorded the axial spine and thorax surface rotation during forward bending movement using an optoelectronic three-dimensional motion analyzer (BTS Smart System) with 60 Hz sampling rate. Twenty-six passive markers (diameter 0,5 and 1 cm) were used to define chest wall, spine and pelvis. Spine was reconstructed as follows: we placed six markers on the spinous processes (SP) of the second (D2), fifth (D5), ninth (D9) thoracic vertebra, above the SP of the third (L3), the fourth (L4) lumbar vertebra and above SP of the first sacral vertebra (S1). Thorax was reconstructed by placing fourteen markers: six markers above the rear corners of the second (2ANGdx, 2ANGsx), fifth (5ANGdx, 5ANGsx), ninth (9ANGdx, 9ANGsx) couple of ribs, one marker above the xiphoid process (PX), one marker above incisura jugularis(FG), six markers over the joints between the ribs and the cartilage of the second (2SCdx, 2SCsx) fifth (5SCdx, 5SCsx), ninth (9SCdx, 9SCsx ) pair of ribs. Pelvis was reconstructed by placing four markers upon right and left anterior superior iliac spine (SIASdx, SIASsx), and upon right and left posterior superior iliac spine (SIPSdx, SIPSsx). Joint coordinate system according to International Society of Biomechanics recommendation was adopted (axes X for inclination, axes Z for flexion/extension, axes Y for rotation) (2). To study the movement of the spine and thorax we have designed four virtual planes. The first (p1) between D2-2SCdx-2SCsx, the second (p2) between D5-5CCdx-5CCsx), the third (p3) between D9-9CCdx-9CCsx, the fourth (R) between S1-SIASdx-SIASsx. Each patient was examined during the forward flexion of the trunk starting from a standing position (F1) and from a seated position (F2) to exclude the influence of leg length inequalities. All the angular values of D5-D9-L3-L5 and of p1, p2, p3, R were calculated. We used Student t-Test for paired samples to test by means the difference pattern of forward bending between F1 and F2 for the whole sample. The significance level was set at 5% for all statistical analyses (p<0,05). We observed no differences between the amplitudes of the movements in rotation and tilt during F1 an F2 of D5-D9-L3-L5 (p>0,05). In addition, no significant correlation was found for all comparison between angular values of p1 versus p2 versus p3 versus R during F1 and F2 around X and Y. Instead a significant correlation between F1 and F2 were found in p1 versus p3 around Z (p<0,001) and p3 versus R around Z (p<0,001). During AT we observe in all subjects a rigid spine with the exception of the dorsal spine with fulcrum in D9/p3. The present study confirm the possibility to use this non-invasive protocol for deformity assessment in AIS patients. Further investigations into this matter should be extended to a larger sample of participants to investigate the movement of the spine and thorax in AIS. REFERENCES 1) Wu Ge, Van der Helm F, Veeger H, et al. Isb recommendation on definition of joint coordinate system of various joint for reporting of human joint motion – Part I: ankle, hip and spine. Journal of Biomechanics 2002; 35: 543-48. 2) Stokes IA, Moreland MS. Measurement of the shape of the surface of the back in patients with scoliosis. The standing and forward-bending positions. Journal of Bone Joint Surgery America 1987; 69(2):203-11.