Joeffroy Otayek

Are the sagittal cervical radiographic modifiers of the Ames-ISSG classification specific to adult cervical deformity?

OBJECTIVEThe Ames-International Spine Study Group (ISSG) classification has recently been proposed as a tool for adult cervical deformity evaluation. This classification includes three radiographic cervical sagittal modifiers that have not been evaluated in asymptomatic adults. The aim of this study was to determine whether the sagittal radiographic modifiers described in the Ames-ISSG cervical classification are encountered in asymptomatic adults without alteration of health-related quality of life (HRQOL).METHODSThe authors conducted a cross-sectional study of subjects with an age ≥ 18 years and no cervical or back-related complaints or history of orthopedic surgery. All subjects underwent full-body biplanar radiographs with the measurement of cervical, segmental, and global alignment and completed the SF-36 HRQOL questionnaire. Subjects were classified according to the sagittal radiographic modifiers (chin-brow vertical angle [CBVA], mismatch between T1 slope and cervical lordosis [TS-CL], and C2-7 sagittal vertical axis [cSVA]) of the Ames-ISSG classification for cervical deformity, which also includes a qualitative descriptor of cervical deformity, the modified Japanese Orthopaedic Association (mJOA) myelopathy score, and the Scoliosis Research Society (SRS)-Schwab classification for spinal deformity assessment. Characteristics of the subjects classified by the different modifier grades were compared.RESULTSOne hundred forty-one asymptomatic subjects (ages 18-59 years, 71 females) were enrolled in the study. Twenty-seven (19.1%) and 61 (43.3%) subjects were classified as grade 1 in terms of the TS-CL and CBVA modifiers, respectively. Ninety-eight (69.5%) and 4 (2.8%) were grade 2 for these same respective modifiers. One hundred thirty-six (96.5%) subjects had at least one modifier at grade 1 or 2. There was a significant relationship between patient age and grades of TS-CL (p < 0.001, Cramers V [CV] = 0.32) and CBVA (p = 0.04, CV = 0.22) modifiers. The HRQOL, global alignment, and segmental alignment parameters were similar among the subjects with different modifier grades (p > 0.05).CONCLUSIONSThe CBVA and TS-CL radiographic modifiers of the Ames-ISSG classification do not seem to be specific to subjects with cervical deformities and can occur in asymptomatic subjects without alteration in HRQOL.

O 057 - How do postural parameters vary during walking in asymptomatic adults? A registration technique of subject-specific 3D skeletal reconstruction during gait

Postural skeletal alignment is altered with age due to intervertebral ndisc and joint degeneration, consequently affecting quality of life (QoL) nand activities of daily living, such as gait. Postural alignment parameters nof the spine, pelvis, hips and lower limbs, measured on static nstanding radiographs, have been widely studied in asymptomatic subjects nand subjects affected by various pathologies. However, while most nof these parameters are positional and could vary during gait, there are ncurrently no studies investigating how they are modified during nwalking.

O 034 – Variation of the sagittal vertical axis during walking and its determinants

Patients with adult spinal deformities (ASD) are known to have naltered postural alignment affecting their quality of life and activities nof daily living, especially gait. The Sagittal Vertical Axis (SVA), a npostural parameter calculated as the distance between the posterior ncorner of the sacrum and the C7-plumbline on full-body sagittal nradiographs [1], has been shown to be highly altered in ASD. Even nthough this parameter is positional and could vary during gait, no nstudies have investigated its variation during walking even in nasymptomatic subjects.

O 068 – The variation of lateral and posterior coverage of the femoral head by the acetabulum during walking influences stability during gait

Gait balance,assessed by the angle formed between the line joining the center-of-mass (COM) to the center-of-pressure (COP) and the vertical during gait, has been shown to be related to skeletal-postural and anthro-pometric parameters [1]. Although skeletal-postural parameters are mea-sured on standing radiographs, they are known to vary during gait. There are currently no studies evaluating how the variations of skeletal-postural parameters during gait influence subject’s balance during walking. n nResearch question nHow does the variation of skeletal-postural parameters during gait influence subject’s balance during walking? n nMethods n72 asymptomatic subjects (age: 28.6 ± 11 years [18–59], 29F) underwent 3D gait analysis [2] with additional markers on the thighs and shanks. The COM-COP angle with the vertical was calculated in both the frontal and sagittal planes during the gait cycle [3]( Fig. 1).Subjects then underwent low-dose full-body biplanar X-rays with themarkers still in place. 3D reconstructions were obtained for the spine,pelvis and lower limbs. 3D bones were registered at each frame of thegait cycle [4]. A new technique developed for this study, utilizingfiniteelement modelling, was used to reduce soft tissue artefacts. Skeletal-postural parameters were then computed during the gait cycle, using the 3D registered bones, at each time frame (Fig. 2); mean, minimum, maximum and ROM were calculated on the waveforms during the gaitcycle. In order to determine which varying skeletal-postural parameterduring gait determined the variation of the COM-COP angles, univariate analysis (Pearson’s correlation) followed by a multivariate analysis (stepwise-multiple-linear-regression models) were computed; COM-COP parameters were the dependant variables and varying skeletal-postural parameters during gait were the independent variables. n nResults n Minimum (−14.2 ± 3.4°) and average (3.1 ± 1.6°) of the sagittal COM-COP angle were found to be determined by the minimum of the posterior coverage (post_cov) of the femoral head by the acetabulum during gait (β= 0.40; R2 = 0.16; p = 0.003 andβ= 0.32; R2 = 0.1;p = 0.001, respectively). ROM (33.9 ± 5.1°) and maximum(19.7 ± 2.8°) of the sagittal COM-COP angle were found to be related to the ROM (β= 0.29; R2 = 0.09; p = 0.03) and maximum (β= 0.34;R2 = 0.11; p = 0.006) of the acetabular abduction during gait, respectively. ROM of the frontal COM-COP angle (8.8 ± 2.51°) was found to be determined by the average of the post_cov (β= 0.51;R2 = 0.26; p = 0.004) during gait. n nDiscussion nThis is the first study to evaluate how the variation of skeletal-postural parameters during walking influences the stability during gait(Fig. 3). A less pronounced posterior coverage of the acetabulum during gait predisposes to more instability by decreasing the minimum COM-COP angle; a more pronounced acetabular abduction (decreased lateralcoverage) during gait predisposes to more instability by increasing the ROM and the maximum of the COM-COP angle. Therefore, gait instability in the sagittal plane seems to be influenced by the variation of the posterior and lateral coverage of the femoral head by the acet-abulum during walking