RESUMEN

PURPOSE: The modification of cervical lordosis (CL) after adolescent idiopathic scoliosis (AIS) surgery is influenced by the correction of thoracic hypokyphosis. The quantification of the increase of CL as a function of the increase of thoracic kyphosis (TK) has never been calculated. METHODS: A total of 92 consecutive AIS patients who underwent a posterior thoracic selective fusion, corrected by simultaneous translation on 2 rods technique, with minimum 24-month follow-up, were analyzed from a prospective database. We evaluated global sagittal kyphosis and lordosis. CL was divided by the horizontal line in proximal (PCL) and distal cervical lordosis (DCL), likewise TK in proximal (PTK) and distal TK (DTK), and lumbar lordosis (LL) in proximal (PLL) and distal LL (DLL). RESULTS: The mean TK gain was 16°, 14° and 28° in the whole cohort, normokyphosis group and hypokyphosis group, respectively. The mean DCL gain was, respectively, 9°, 7° and 20° and the mean CL gain 8°, 5° and 21°. There was a strong correlation between TK gain and CL gain (coefficient = 0.86) and between TK gain and DCL gain (coefficient = 0.74). The regression equation was defined as DCLgain = - 3 + 0.75 × TKgain (p < 0.0001) corresponding on average to 60% of the TK gain. CONCLUSION: 60% of the TK gain was transferred to DCL gain. Correlations reflect the geometrical equivalence between PTK and DCL. The use of sagittal global measurements shows that DCL is equivalent to PTK and can be expressed as a function of pelvic parameters (DCL = PT + LL-PI). DCL must be considered to optimize the postoperative sagittal alignment of the spine.

Asunto(s)

Cifosis , Lordosis , Escoliosis , Fusión Vertebral , Adolescente , Humanos , Cifosis/diagnóstico por imagen , Cifosis/cirugía , Lordosis/diagnóstico por imagen , Lordosis/cirugía , Estudios Retrospectivos , Escoliosis/diagnóstico por imagen , Escoliosis/cirugía , Fusión Vertebral/efectos adversos , Vértebras Torácicas/diagnóstico por imagen , Vértebras Torácicas/cirugía

RESUMEN

PURPOSE: To evaluate the impact of proximal thoracic segment (T1-T5) on global thoracic kyphosis, as well as its influence on cervical alignment (lordotic, kyphotic or straight) in patients with adolescent idiopathic scoliosis (AIS). METHODS: We conducted a retrospective study of 80 patients with AIS. The inclusion criteria were patients between 10 and 18 years of age with a posteroanterior (PA) and lateral full-length radiographs, excluding those subjected to surgery, orthotic treatment, with other spinal disease or with poor X-ray quality. The parameters evaluated were age, sex, pelvic incidence (PI), sacral slop (SS), pelvic tilt (PT), global sagittal balance (GSB), scoliotic curvatures (differentiated according to primary curve, lumbar modifier and sagittal modifier), cervical spine alignment, thoracic sagittal Cobb angle between T1 and T5, T5 and T12 and between T1 and T12. RESULTS: In patients with AIS, the proximal sagittal thoracic Cobb segment, contrary to the distal, demonstrated a significant positive correlation with cervical spine alignment (p < 0.05). As there is an increase in proximal thoracic angle, there is an increase in cervical lordosis. We also demonstrated that the correlation between an increase in scoliotic curvature and a decrease in kyphosis only occurred in the distal thoracic segment (T5-T12). Relative to the spinopelvic parameters, the PI was not related with the dorsal kyphosis or shape of the cervical spine. CONCLUSIONS: In AIS, proximal (T1-T5) and distal (T5-T12) thoracic kyphosis have different contributions on the global thoracic sagittal curvature and in the phenomenon of hypokyphosis. On the other hand, only the proximal segment is significantly related to the shape of the cervical spine. LEVEL OF EVIDENCE: IV.

Asunto(s)

Desviación Ósea/etiología , Cifosis/etiología , Escoliosis/diagnóstico por imagen , Escoliosis/etiología , Vértebras Torácicas/diagnóstico por imagen , Adolescente , Desviación Ósea/diagnóstico por imagen , Vértebras Cervicales/diagnóstico por imagen , Niño , Femenino , Humanos , Cifosis/diagnóstico por imagen , Masculino , Radiografía , Estudios Retrospectivos

RESUMEN

INTRODUCTION: Complications in the upper thoracic spine are not uncommon after corrective surgery for deformities in adults and adolescents. Proximal junctional failure has been linked to structural osseous or ligamentous failure and proximal junctional kyphosis has been described as an increase in preoperative proximal kyphosis. CASE DESCRIPTION: A 20-year-old male patient intervened after atypical development of idiopathic scoliosis, with rapid progression nearing skeletal maturity. While an increase in the magnitude of the main thoracic curve in the coronal plane was observed, the progression of structural sagittal plane deformity of the proximal thoracic curve was not identified due to poor visualization. This resulted in improper identification of curve type and choice of fusion levels, with progressive residual kyphosis across follow-up. At the age of 27, the patient was re-intervened by means of pedicle subtraction osteotomy in the apical area of the proximal thoracic deformity. Although an adequate correction was achieved, the remaining deformity of 50° and the proximal failure required extending the instrumentation and fusion to the cervical spine. This has shown itself to be an effective technique for correction of proximal residual or progressive symptomatic fixed kyphosis, thereby avoiding the morbidity of the anterior or combined approaches. CONCLUSIONS: In adolescent deformity, an adequate preoperative planning including clinical and radiological study must be carried out, paying special attention to the sagittal plane to identify major and minor structural curves. The pedicle subtraction osteotomy, despite being a demanding technique and not entirely risk-free, has shown itself to be an effective corrective technique.