Comparison of sagittal compensatory mechanism between degenerative and post-traumatic kyphosis in thoracolumbar spine

English Keywords:Thoracolumbar kyphosis  Degenerative kyphosis  Post-traumatic fracture  Sagittal compensation  Spino-pelvic parameter

English Abstract:

  【Abstract】 Objectives: To compare the sagittal compensatory mode between degenerative thoracolumbar kyphosis(DTK) and post-traumatic thoracolumbar kyphosis(PTK). Methods: Retrospective analysis was conducted on 60 patients with thoracolumbar kyphosis treated in our hospital from June 2010 to February 2015 (32 DTK and 28 PTK). For comparison, 30 asymptomatic volunteers were included as control group. The average age of DTK, PTK and control group was 56.0±7.3, 39.0±8.5, 45.5±5.5 years old, respectively. Standing long cassette posteroanterior and lateral X-ray films were taken for each patient. Kyphosis angle(KA), thoracic kyphosis(TK), lumbar lordosis(LL), pelvic incidence(PI), pelvic tilt(PT), sacral slope(SS) and sagittal vertical axis(SVA) were measured. Differences in these spino-pelvic parameters were compared among the three groups. Results: (1)The TK of DTK group and control group was significantly higher than that of PTK group(26.5°±5.8°, 26.0°±6.3° and 23.3°±7.8°, respectively)(P＜0.05), but no difference was found between DTK group and control group(P＞0.05). (2)The LL and SS were significantly lower in DTK group(23.1°±12.4°, 20.4°±7.7°) than those in PTK group(43.4°±7.8°, 30.4°±6.6°) and control group(42.1°±8.5°, 31.1°±5.5°)(P＜0.001). But there were no significant differences between PTK group and control group(P＞0.05). Additionally, DTK group had higher SVA and PT(62.7±17.5mm, 26.1°±11.9°) than PTK group(16.7±7.1mm, 16.7°±8.6°) and control group(15.8±7.4mm, 15.4°±6.6°)(P＜0.001), but the values of SVA and PT were similar in PTK group and control group(P＞0.05). (3)There was no significant difference in KA between DTK group and PTK group(46.7°±12.8° vs 46.0°±13.8°); no significant difference was found in PI among the three groups(45.5°±9.7°, 46.1°±8.8°, 45.1°±8.8°, P＞0.05). Conclusions: Patients with DTK tend to present sagittal decompensation with decreased LL, retroversion of the pelvis and anterior-shifted SVA. However, regional kyphosis and decreased TK are the common sagittal profile in PTK patients with balanced spino-pelvic alignment.