POS1272 DIFFERENCES IN RANGE OF MOTION AND MECHANICAL MUSCLE CHARACTERISTICS AMONG INFLAMMATORY AND MECHANICAL SPINAL PAIN: A CASE-CONTROL STUDY

Abstract

Background: The spinal range of motion (ROM) and the mechanical muscle properties (MMPs) at rest are defined as relevant clinical factors in inflammatory (i.e. axial Spondyloarthritis ‐axSpA) and mechanical spinal pain (i.e. Mechanical Neck pain ‐NP‐or Mechanical Low Back pain ‐LBP‐). Nevertheless, there is not enough evidence regarding if ROM and MMPs are different in both types of spinal pain. Objectives: To identify differences between axSpA patients and NP or LBP subjects, in cervical and lumbar ROMs and MMPs at rest. Methods: Subjects with axSpA and with NP or LBP composed the Inflammatory pain Group (IG) and the Mechanical pain Group (MG), respectively. For the analysis of the spinal mobility, two Inertial Measurement Units (IMU) were used. For both spinal regions (cervical and lumbar ‐Figure 1A,B) 3 repetitions of flexion‐extension, lateral‐flexion, and rotation were executed separately[1]. A record of the MMPs using a hand myotonometer was made in both lumbar (muscular belly of the erector spinal ‐Figure 1D) and cervical (the semispinalis capitis muscles at C4 ‐Figure 1C) spine in prone position with both arms along the body. The MMPs recorded in this study included: frequency (tone), stiffness, decrement (elasticity), relaxation and creep (viscosity). The order of assessments (right/left) was randomized. Since no side‐to‐side differences in either group were observed, the mean of both sides was considered. Student‐t tests were used to compare the groups, and Cohen‐d effect size index was estimated as a measure of the size of difference. P0.05 was considered statistically significant. Results: 61 subjects in IG (42% women, age 41±12 years, BMI 25±3) and 66 in MG (51% women, age 38±13 years, BMI 25±3) participated in this study. No significant differences were identified in sociodemographic data between both groups. Table 1 shows ROM and MMPs between groups. All lumbar ROMs were significantly lower in the IG, with the different between means achieving the minimum clinical important difference (≥8°) for flexion‐extension and lateroflexion. On the contrary, the cervical ROMs were not different between groups, and showed the highest variability, probably related to compensatory mechanisms due to lumbar ROMs restrictions. The IG showed greater Lumbar stiffness than the MG with large effect size (d=0.94). No other difference in MMPs was identified in this region (p≥0.05). Regarding the cervical region, all MMPs showed differences between groups. Thus, tone, stiffness and elasticity were higher in the IG, while relaxation and viscosity were lower. In all cases, except for decrement, the effect size was from moderate to large (0.6