Static and dynamic sagittal lumbar apex: a new concept for the assessment of lumbar lordosis distribution in spinal deformity.

PURPOSE: Sagittal lumbar apex has been demonstrated to be a key parameter in sagittal plane morphology. Our aim was to understand its behavior with postural changes, analyzing two different concepts of lumbar apex. MATERIALS AND METHODS: Prospective observational study with a cohort of patients presenting sagittal malalignment identified from a monocenter database of adult spinal deformities (ASD). Inclusion criteria were age > 30 years, SVA > 40 mm, and/or PT > 20. All patients had full-spine EOS radiographs in 2 different positions: (P1: natural position) and position 2 (P2: compensated position). Sagittal alignment, spinopelvic values, and two different methods of assessing lordosis apex location were analyzed in both P1 and P2 positions. Changes between P1 and P2 were compared using a paired t test with a significance level at p < 0.05. RESULTS: Twenty-five patients were recruited (21 women and 4 men). The mean age was 64.8 years (range 21-79). The patient's main compensation was based on an increase in the femoral shaft angle, and pelvic retroversion, with a subsequent decrease in sacral slope, and therefore of the lower lumbar arc. When the lumbar apex was calculated as the most anterior point touching the vertical line in a lateral radiograph, postural compensation changes modified its location usually shifting it to a more caudal position. When the lumbar apex was assessed as the most distant point of the global lumbar lordosis, its position remained stable regardless of compensation. CONCLUSIONS: Postural changes can modify the location of the lumbar apex when understanding its location as the cornerstone of sagittal plane harmonic distribution. This concept can be useful as an additional sign to assess compensation. However, if the lumbar apex was calculated as the angular point of the global lordosis, its position remained stable regardless of postural changes. This concept can help to mold lumbar lordosis in ASD surgery. LEVEL OF EVIDENCE IV: Diagnostic: individual cross-sectional studies with consistently applied reference standard and blinding.

Traumatic Fracture: Dislocation of Cervicothoracic Junction-Grand Round Presentation of C7-T1 Instabilities and Different Instrumentation Techniques.

INTRODUCTION: Acute traumatic cervicothoracic junction spinal lesions are rare disorders and poorly documented. We report a case of a traumatic cervicothoracic fracture-dislocation. We present our experience in the operative treatment of an unstable fracture-dislocation at the cervicothoracic junction. Materials and Method. A seventy-year-old man was transferred to our hospital. We found paresthesia in the corresponding dermatome of C7 and C8 bilaterally. Initial CT scan shows vertebral body fracture of T1 with retropulsion into the spinal canal and anteroposterior dislocation of cervicothoracic junction type C according to AOSpine subaxial injury. Traumatic disc material at C7-T1 was removed by anterior cervical discectomy and fusion of C6-T2. Fixation was done from C6 to T2 in the prone position. RESULTS: At one-year postoperative follow-up, radiographs revealed bony fusion at the level of C7-T1, and the patient had no major functional disability. CONCLUSION: We opted for the ventral-dorsal approach in our case for maximum stabilization and to prevent mechanical complications.

Effect of sagittal shape on proximal junctional kyphosis following thoracopelvic corrective fusion for adult spinal deformity: postoperative inflection vertebra cranial to T12 is a significant risk factor.

STUDY DESIGN: This was a retrospective analysis of a prospectively collected consecutive case series of patients with adult spinal deformity (ASD). OBJECTIVE: This study aimed to investigate the impact of the geometrical sagittal shape of the corrected spine on the development of proximal junctional kyphosis (PJK). Several studies have documented risk factors for PJK in ASD surgery. Geometrical assessment is vital for evaluating sagittal spinal deformity. It is essential to assess the postoperative geometrical shape of the spine and the location of the correction in the spine to decrease postoperative junctional stress and PJK. METHODS: Consecutive patients with ASD who underwent corrective fusion with long constructs to the pelvis were included. Patients with neuromuscular disease, congenital and adolescent scoliosis, infection, and spinal tumor were excluded. We investigated the spinopelvic and geometrical parameters of the whole spine. The locations of the thoracic and lumbar apical vertebrae and the inflection vertebrae (IV), where the curvature of the associated adjacent vertebral bodies changes from kyphosis to lordosis, were investigated. The subjects were divided into PJK included patients who underwent revision surgery for junctional failure or with a change in proximal junctional angle ≥ 20°, and non-PJK groups. RESULTS: A total of 139 patients (mean age, 69.6 years; range 18-82 years) were included. There were 47 and 92 patients in the PJK and non-PJK groups, respectively. The IV were located significantly cranial and posterior, the lumbar apex were located significantly posterior in the PJK group at the immediate postoperative time points. The significant risk factors for PJK on binary logistic regression were cranial IV and posterior lumbar apical vertebrae. The incidence of PJK in patients with IV at T12 or cranial tends PJK significantly higher (69%) than at L1 or caudal (26%). CONCLUSIONS: Geometrical spinal shape should be taken into account to reduce the rate of postoperative mechanical complications. LEVEL OF EVIDENCE: Level of evidence III.