Recruitment of compensatory mechanisms in XXXX is age and regional deformity dependent: a full-standing axis analysis of key radiographical parameters.

@entity1 @entity1513 @entity1515 @entity893
STUDY DESIGN: Retrospective review, full-body radiographical analysis of adult @entity1 with @entity893 ( @entity893 ). OBJECTIVE: To investigate the compensatory mechanisms involved in the sagittal plane of the body after progressive @entity893 and to study the impact of age on compensatory mechanism recruitment. SUMMARY OF BACKGROUND DATA: @entity1 with @entity893 recruit compensatory mechanisms to maintain erect posture and horizontal gaze. Mechanisms such as pelvic retroversion, knee flexion, and pelvic shift have been proposed, but how they contribute and how age affects their recruitment are poorly understood. METHODS: Retrospective review of adult @entity1 with @entity893 who underwent full-standing axis stereoradiography (EOS imaging). Radiographical measurements were performed with Surgimap. @entity1 were categorized on the basis of the mismatch between pelvic incidence (PI) and @entity1515 (PI-LL). Compensatory mechanisms were normalized to each @entity1 's PI-LL and compared by mismatch groups. In addition, @entity1 were subcategorized into 2 age groups (>= 65 and <65 yr) and compared within the same groups of mismatch. RESULTS: A total of 161 @entity1 with a mean age of 62.93    12.8 years. Mean sagittal vertical axis = 62.3    61.5 mm; pelvic tilt (PT) = 29.2      8.4  ; and PI-LL = 21.0      14.9  . Mismatch groups were as follows: group 1: PI-LL 0  -10  ; group 2: 10  -20  ; group 3: 20  -30  ; and group 4: >30  . There were significant differences between all groups with regard to @entity1513 ( @entity1513 ), PT, knee flexion angle, and pelvic shift by analysis of variance (P < 0.001). As PI-LL increased, @entity1513 and PT contribution to the compensation cascade decreased and knee flexion angle and pelvic shift contribution increased. @entity1 with PI-LL of more than 30   who were older had significantly less PT and more @entity1513 than @entity1 with similar PI-LL who were younger. CONCLUSION: Spinopelvic mismatch is an important driver in @entity893 . Pelvic retroversion and flattening of @entity1513 (reduction) become exhausted with increasing mismatch, at which point there seems to be a steady transfer of compensation toward significant participation of the lower limbs. Further analysis suggests differential recruitment of these compensatory mechanisms based upon age. LEVEL OF EVIDENCE: 3.
